diff --git a/make/autoconf/lib-alsa.m4 b/make/autoconf/lib-alsa.m4
index 19a91f94809..8d0fb324cd0 100644
--- a/make/autoconf/lib-alsa.m4
+++ b/make/autoconf/lib-alsa.m4
@@ -70,6 +70,25 @@ AC_DEFUN_ONCE([LIB_SETUP_ALSA],
         PKG_CHECK_MODULES(ALSA, alsa, [ALSA_FOUND=yes], [ALSA_FOUND=no])
       fi
     fi
+    if test "x$ALSA_FOUND" = xno; then
+      # If we have sysroot set, and no explicit library location is set,
+      # look at known locations in sysroot.
+      if test "x$SYSROOT" != "x" && test "x${with_alsa_lib}" == x; then
+        if test -f "$SYSROOT/usr/lib64/libasound.so" && test "x$OPENJDK_TARGET_CPU_BITS" = x64; then
+          ALSA_LIBS="-L$SYSROOT/usr/lib64 -lasound"
+          ALSA_FOUND=yes
+        elif test -f "$SYSROOT/usr/lib/libasound.so"; then
+          ALSA_LIBS="-L$SYSROOT/usr/lib -lasound"
+          ALSA_FOUND=yes
+        elif test -f "$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libasound.so"; then
+          ALSA_LIBS="-L$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI -lasound"
+          ALSA_FOUND=yes
+        elif test -f "$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU_AUTOCONF-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libasound.so"; then
+          ALSA_LIBS="-L$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU_AUTOCONF-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI -lasound"
+          ALSA_FOUND=yes
+        fi
+      fi
+    fi
     if test "x$ALSA_FOUND" = xno; then
       AC_CHECK_HEADERS([alsa/asoundlib.h],
           [
diff --git a/make/autoconf/lib-x11.m4 b/make/autoconf/lib-x11.m4
index b1902a432a1..6849b4a26c7 100644
--- a/make/autoconf/lib-x11.m4
+++ b/make/autoconf/lib-x11.m4
@@ -71,9 +71,9 @@ AC_DEFUN_ONCE([LIB_SETUP_X11],
           elif test -f "$SYSROOT/usr/lib/libX11.so"; then
             x_libraries="$SYSROOT/usr/lib"
           elif test -f "$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libX11.so"; then
-            x_libraries="$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libX11.so"
+            x_libraries="$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI"
           elif test -f "$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU_AUTOCONF-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libX11.so"; then
-            x_libraries="$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU_AUTOCONF-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI/libX11.so"
+            x_libraries="$SYSROOT/usr/lib/$OPENJDK_TARGET_CPU_AUTOCONF-$OPENJDK_TARGET_OS-$OPENJDK_TARGET_ABI"
           fi
         fi
       fi
diff --git a/make/test/JtregNativeHotspot.gmk b/make/test/JtregNativeHotspot.gmk
index ecc7e34c917..fee5fe86031 100644
--- a/make/test/JtregNativeHotspot.gmk
+++ b/make/test/JtregNativeHotspot.gmk
@@ -871,6 +871,7 @@ ifeq ($(call isTargetOs, windows), true)
   BUILD_HOTSPOT_JTREG_EXECUTABLES_CFLAGS_exeFPRegs := -MT
   BUILD_HOTSPOT_JTREG_EXCLUDE += exesigtest.c libterminatedThread.c libTestJNI.c libCompleteExit.c libMonitorWithDeadObjectTest.c libTestPsig.c exeGetCreatedJavaVMs.c
   BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libnativeStack := java.base:libjvm
+  BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libVThreadEventTest := java.base:libjvm
 else
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libbootclssearch_agent += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libsystemclssearch_agent += -lpthread
@@ -1509,6 +1510,7 @@ else
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libCompleteExit += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libMonitorWithDeadObjectTest += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libnativeStack += -lpthread
+  BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libVThreadEventTest := java.base:libjvm
   BUILD_HOTSPOT_JTREG_EXECUTABLES_LIBS_exeGetCreatedJavaVMs := -lpthread
   BUILD_HOTSPOT_JTREG_EXECUTABLES_JDK_LIBS_exeGetCreatedJavaVMs := java.base:libjvm
 
diff --git a/src/demo/share/jfc/SwingSet2/SwingSet2.java b/src/demo/share/jfc/SwingSet2/SwingSet2.java
index 13b3d63a693..75eeb4e3657 100644
--- a/src/demo/share/jfc/SwingSet2/SwingSet2.java
+++ b/src/demo/share/jfc/SwingSet2/SwingSet2.java
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2024, Oracle and/or its affiliates. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -848,7 +848,14 @@ private void updateThisSwingSet() {
         if (frame == null) {
             SwingUtilities.updateComponentTreeUI(this);
         } else {
+            if (currentLookAndFeel.name.contains("GTK")) {
+                this.setPreferredSize(new Dimension(PREFERRED_WIDTH + 260, PREFERRED_HEIGHT + 80));
+            } else {
+                this.setPreferredSize(new Dimension(PREFERRED_WIDTH, PREFERRED_HEIGHT));
+            }
+
             SwingUtilities.updateComponentTreeUI(frame);
+            frame.pack();
         }
 
         SwingUtilities.updateComponentTreeUI(popupMenu);
diff --git a/src/hotspot/cpu/aarch64/aarch64.ad b/src/hotspot/cpu/aarch64/aarch64.ad
index d4b3d634438..d8db75961d8 100644
--- a/src/hotspot/cpu/aarch64/aarch64.ad
+++ b/src/hotspot/cpu/aarch64/aarch64.ad
@@ -2745,10 +2745,7 @@ typedef void (MacroAssembler::* mem_vector_insn)(FloatRegister Rt,
     }
 
     if (index == -1) {
-      /* If we get an out-of-range offset it is a bug in the compiler,
-         so we assert here. */
-      assert(Address::offset_ok_for_immed(disp, exact_log2(size_in_memory)), "c2 compiler bug");
-      /* Fix up any out-of-range offsets. */
+      // Fix up any out-of-range offsets.
       assert_different_registers(rscratch1, base);
       Address addr = Address(base, disp);
       addr = __ legitimize_address(addr, size_in_memory, rscratch1);
@@ -3348,7 +3345,11 @@ encode %{
     int scale = $mem$$scale;
     int disp = $mem$$disp;
     if (index == -1) {
-      __ prfm(Address(base, disp), PSTL1KEEP);
+      // Fix up any out-of-range offsets.
+      assert_different_registers(rscratch1, base);
+      Address addr = Address(base, disp);
+      addr = __ legitimize_address(addr, 8, rscratch1);
+      __ prfm(addr, PSTL1KEEP);
     } else {
       Register index_reg = as_Register(index);
       if (disp == 0) {
@@ -4229,9 +4230,9 @@ operand immIOffset16()
   interface(CONST_INTER);
 %}
 
-operand immLoffset()
+operand immLOffset()
 %{
-  predicate(Address::offset_ok_for_immed(n->get_long(), 0));
+  predicate(n->get_long() >= -256 && n->get_long() <= 65520);
   match(ConL);
 
   op_cost(0);
@@ -5341,6 +5342,34 @@ operand indOffL16(iRegP reg, immLoffset16 off)
   %}
 %}
 
+operand indirectX2P(iRegL reg)
+%{
+  constraint(ALLOC_IN_RC(ptr_reg));
+  match(CastX2P reg);
+  op_cost(0);
+  format %{ "[$reg]\t# long -> ptr" %}
+  interface(MEMORY_INTER) %{
+    base($reg);
+    index(0xffffffff);
+    scale(0x0);
+    disp(0x0);
+  %}
+%}
+
+operand indOffX2P(iRegL reg, immLOffset off)
+%{
+  constraint(ALLOC_IN_RC(ptr_reg));
+  match(AddP (CastX2P reg) off);
+  op_cost(0);
+  format %{ "[$reg, $off]\t# long -> ptr" %}
+  interface(MEMORY_INTER) %{
+    base($reg);
+    index(0xffffffff);
+    scale(0x0);
+    disp($off);
+  %}
+%}
+
 operand indirectN(iRegN reg)
 %{
   predicate(CompressedOops::shift() == 0);
@@ -5431,7 +5460,7 @@ operand indOffIN(iRegN reg, immIOffset off)
   %}
 %}
 
-operand indOffLN(iRegN reg, immLoffset off)
+operand indOffLN(iRegN reg, immLOffset off)
 %{
   predicate(CompressedOops::shift() == 0);
   constraint(ALLOC_IN_RC(ptr_reg));
@@ -5664,6 +5693,17 @@ operand iRegL2I(iRegL reg) %{
   interface(REG_INTER)
 %}
 
+operand iRegL2P(iRegL reg) %{
+
+  op_cost(0);
+
+  match(CastX2P reg);
+
+  format %{ "l2p($reg)" %}
+
+  interface(REG_INTER)
+%}
+
 opclass vmem2(indirect, indIndex, indOffI2, indOffL2);
 opclass vmem4(indirect, indIndex, indOffI4, indOffL4);
 opclass vmem8(indirect, indIndex, indOffI8, indOffL8);
@@ -5680,21 +5720,21 @@ opclass vmem16(indirect, indIndex, indOffI16, indOffL16);
 // instruction defs. we can turn a memory op into an Address
 
 opclass memory1(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indIndex, indOffI1, indOffL1,
-               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN);
+                indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indirectX2P, indOffX2P);
 
 opclass memory2(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indIndex, indOffI2, indOffL2,
-               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN);
+                indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indirectX2P, indOffX2P);
 
 opclass memory4(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indIndex, indOffI4, indOffL4,
-               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN);
+                indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN, indirectX2P, indOffX2P);
 
 opclass memory8(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indIndex, indOffI8, indOffL8,
-               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN);
+                indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN, indirectX2P, indOffX2P);
 
 // All of the memory operands. For the pipeline description.
 opclass memory(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indIndex,
                indOffI1, indOffL1, indOffI2, indOffL2, indOffI4, indOffL4, indOffI8, indOffL8,
-               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN);
+               indirectN, indIndexScaledN, indIndexScaledI2LN, indIndexI2LN, indIndexN, indOffIN, indOffLN, indirectX2P, indOffX2P);
 
 
 // iRegIorL2I is used for src inputs in rules for 32 bit int (I)
@@ -5711,6 +5751,7 @@ opclass memory(indirect, indIndexScaled, indIndexScaledI2L, indIndexI2L, indInde
 // movw is actually redundant but its not too costly.
 
 opclass iRegIorL2I(iRegI, iRegL2I);
+opclass iRegPorL2P(iRegP, iRegL2P);
 
 //----------PIPELINE-----------------------------------------------------------
 // Rules which define the behavior of the target architectures pipeline.
@@ -9811,7 +9852,7 @@ instruct addI_reg_imm_i2l(iRegINoSp dst, iRegL src1, immIAddSub src2) %{
 %}
 
 // Pointer Addition
-instruct addP_reg_reg(iRegPNoSp dst, iRegP src1, iRegL src2) %{
+instruct addP_reg_reg(iRegPNoSp dst, iRegPorL2P src1, iRegL src2) %{
   match(Set dst (AddP src1 src2));
 
   ins_cost(INSN_COST);
@@ -9826,7 +9867,7 @@ instruct addP_reg_reg(iRegPNoSp dst, iRegP src1, iRegL src2) %{
   ins_pipe(ialu_reg_reg);
 %}
 
-instruct addP_reg_reg_ext(iRegPNoSp dst, iRegP src1, iRegIorL2I src2) %{
+instruct addP_reg_reg_ext(iRegPNoSp dst, iRegPorL2P src1, iRegIorL2I src2) %{
   match(Set dst (AddP src1 (ConvI2L src2)));
 
   ins_cost(1.9 * INSN_COST);
@@ -9841,7 +9882,7 @@ instruct addP_reg_reg_ext(iRegPNoSp dst, iRegP src1, iRegIorL2I src2) %{
   ins_pipe(ialu_reg_reg);
 %}
 
-instruct addP_reg_reg_lsl(iRegPNoSp dst, iRegP src1, iRegL src2, immIScale scale) %{
+instruct addP_reg_reg_lsl(iRegPNoSp dst, iRegPorL2P src1, iRegL src2, immIScale scale) %{
   match(Set dst (AddP src1 (LShiftL src2 scale)));
 
   ins_cost(1.9 * INSN_COST);
@@ -9856,7 +9897,7 @@ instruct addP_reg_reg_lsl(iRegPNoSp dst, iRegP src1, iRegL src2, immIScale scale
   ins_pipe(ialu_reg_reg_shift);
 %}
 
-instruct addP_reg_reg_ext_shift(iRegPNoSp dst, iRegP src1, iRegIorL2I src2, immIScale scale) %{
+instruct addP_reg_reg_ext_shift(iRegPNoSp dst, iRegPorL2P src1, iRegIorL2I src2, immIScale scale) %{
   match(Set dst (AddP src1 (LShiftL (ConvI2L src2) scale)));
 
   ins_cost(1.9 * INSN_COST);
@@ -9889,7 +9930,7 @@ instruct lshift_ext(iRegLNoSp dst, iRegIorL2I src, immI scale, rFlagsReg cr) %{
 // Pointer Immediate Addition
 // n.b. this needs to be more expensive than using an indirect memory
 // operand
-instruct addP_reg_imm(iRegPNoSp dst, iRegP src1, immLAddSub src2) %{
+instruct addP_reg_imm(iRegPNoSp dst, iRegPorL2P src1, immLAddSub src2) %{
   match(Set dst (AddP src1 src2));
 
   ins_cost(INSN_COST);
diff --git a/src/hotspot/cpu/aarch64/gc/shenandoah/c1/shenandoahBarrierSetC1_aarch64.cpp b/src/hotspot/cpu/aarch64/gc/shenandoah/c1/shenandoahBarrierSetC1_aarch64.cpp
index c02f93313b3..261502d5823 100644
--- a/src/hotspot/cpu/aarch64/gc/shenandoah/c1/shenandoahBarrierSetC1_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/gc/shenandoah/c1/shenandoahBarrierSetC1_aarch64.cpp
@@ -41,8 +41,6 @@ void LIR_OpShenandoahCompareAndSwap::emit_code(LIR_Assembler* masm) {
   Register tmp2 = _tmp2->as_register();
   Register result = result_opr()->as_register();
 
-  ShenandoahBarrierSet::assembler()->iu_barrier(masm->masm(), newval, rscratch2);
-
   if (UseCompressedOops) {
     __ encode_heap_oop(tmp1, cmpval);
     cmpval = tmp1;
@@ -102,10 +100,6 @@ LIR_Opr ShenandoahBarrierSetC1::atomic_xchg_at_resolved(LIRAccess& access, LIRIt
   value.load_item();
   LIR_Opr value_opr = value.result();
 
-  if (access.is_oop()) {
-    value_opr = iu_barrier(access.gen(), value_opr, access.access_emit_info(), access.decorators());
-  }
-
   assert(type == T_INT || is_reference_type(type) LP64_ONLY( || type == T_LONG ), "unexpected type");
   LIR_Opr tmp = gen->new_register(T_INT);
   __ xchg(access.resolved_addr(), value_opr, result, tmp);
diff --git a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
index 5db29729239..06f43820156 100644
--- a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
@@ -47,7 +47,7 @@ void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, Dec
                                                        Register src, Register dst, Register count, RegSet saved_regs) {
   if (is_oop) {
     bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
-    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahIUBarrier || ShenandoahLoadRefBarrier) {
+    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahLoadRefBarrier) {
 
       Label done;
 
@@ -300,14 +300,6 @@ void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm,
   __ leave();
 }
 
-void ShenandoahBarrierSetAssembler::iu_barrier(MacroAssembler* masm, Register dst, Register tmp) {
-  if (ShenandoahIUBarrier) {
-    __ push_call_clobbered_registers();
-    satb_write_barrier_pre(masm, noreg, dst, rthread, tmp, rscratch1, true, false);
-    __ pop_call_clobbered_registers();
-  }
-}
-
 //
 // Arguments:
 //
@@ -398,8 +390,7 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet
   if (val == noreg) {
     BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), noreg, noreg, noreg, noreg);
   } else {
-    iu_barrier(masm, val, tmp1);
-    // G1 barrier needs uncompressed oop for region cross check.
+    // Barrier needs uncompressed oop for region cross check.
     Register new_val = val;
     if (UseCompressedOops) {
       new_val = rscratch2;
diff --git a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.hpp b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.hpp
index 375893702e1..ee11b2e73f7 100644
--- a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.hpp
+++ b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.hpp
@@ -60,9 +60,6 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
   void load_reference_barrier(MacroAssembler* masm, Register dst, Address load_addr, DecoratorSet decorators);
 
 public:
-
-  void iu_barrier(MacroAssembler* masm, Register dst, Register tmp);
-
   virtual NMethodPatchingType nmethod_patching_type() { return NMethodPatchingType::conc_data_patch; }
 
 #ifdef COMPILER1
diff --git a/src/hotspot/cpu/aarch64/gc/x/x_aarch64.ad b/src/hotspot/cpu/aarch64/gc/x/x_aarch64.ad
index c7c7165affb..6e401724baa 100644
--- a/src/hotspot/cpu/aarch64/gc/x/x_aarch64.ad
+++ b/src/hotspot/cpu/aarch64/gc/x/x_aarch64.ad
@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+// Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
 // DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 //
 // This code is free software; you can redistribute it and/or modify it
@@ -62,7 +62,13 @@ instruct xLoadP(iRegPNoSp dst, memory8 mem, rFlagsReg cr)
   format %{ "ldr  $dst, $mem" %}
 
   ins_encode %{
-    const Address ref_addr = mem2address($mem->opcode(), as_Register($mem$$base), $mem$$index, $mem$$scale, $mem$$disp);
+    Address ref_addr = mem2address($mem->opcode(), as_Register($mem$$base), $mem$$index, $mem$$scale, $mem$$disp);
+    if (ref_addr.getMode() == Address::base_plus_offset) {
+      // Fix up any out-of-range offsets.
+      assert_different_registers(rscratch1, as_Register($mem$$base));
+      assert_different_registers(rscratch1, $dst$$Register);
+      ref_addr = __ legitimize_address(ref_addr, 8, rscratch1);
+    }
     __ ldr($dst$$Register, ref_addr);
     x_load_barrier(masm, this, ref_addr, $dst$$Register, rscratch2 /* tmp */, barrier_data());
   %}
diff --git a/src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad b/src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad
index 92181e2b6b9..56d45384779 100644
--- a/src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad
+++ b/src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad
@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+// Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
 // DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 //
 // This code is free software; you can redistribute it and/or modify it
@@ -111,7 +111,13 @@ instruct zLoadP(iRegPNoSp dst, memory8 mem, rFlagsReg cr)
   format %{ "ldr  $dst, $mem" %}
 
   ins_encode %{
-    const Address ref_addr = mem2address($mem->opcode(), as_Register($mem$$base), $mem$$index, $mem$$scale, $mem$$disp);
+    Address ref_addr = mem2address($mem->opcode(), as_Register($mem$$base), $mem$$index, $mem$$scale, $mem$$disp);
+    if (ref_addr.getMode() == Address::base_plus_offset) {
+      // Fix up any out-of-range offsets.
+      assert_different_registers(rscratch2, as_Register($mem$$base));
+      assert_different_registers(rscratch2, $dst$$Register);
+      ref_addr = __ legitimize_address(ref_addr, 8, rscratch2);
+    }
     __ ldr($dst$$Register, ref_addr);
     z_load_barrier(masm, this, ref_addr, $dst$$Register, rscratch1);
   %}
diff --git a/src/hotspot/cpu/aarch64/smallRegisterMap_aarch64.inline.hpp b/src/hotspot/cpu/aarch64/smallRegisterMap_aarch64.inline.hpp
index db38b9cf5df..dcba233c9dc 100644
--- a/src/hotspot/cpu/aarch64/smallRegisterMap_aarch64.inline.hpp
+++ b/src/hotspot/cpu/aarch64/smallRegisterMap_aarch64.inline.hpp
@@ -30,8 +30,15 @@
 
 // Java frames don't have callee saved registers (except for rfp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
 private:
   static void assert_is_rfp(VMReg r) NOT_DEBUG_RETURN
                                      DEBUG_ONLY({ assert (r == rfp->as_VMReg() || r == rfp->as_VMReg()->next(), "Reg: %s", r->name()); })
@@ -48,17 +55,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-  #ifdef ASSERT
-    for(int i = 0; i < RegisterMap::reg_count; i++) {
-      VMReg r = VMRegImpl::as_VMReg(i);
-      if (map->location(r, (intptr_t*)nullptr) != nullptr) assert_is_rfp(r);
-    }
-  #endif
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     assert_is_rfp(reg);
     return (address)(sp - frame::sender_sp_offset);
diff --git a/src/hotspot/cpu/arm/smallRegisterMap_arm.inline.hpp b/src/hotspot/cpu/arm/smallRegisterMap_arm.inline.hpp
index 4186eafd35f..08adbbd89d8 100644
--- a/src/hotspot/cpu/arm/smallRegisterMap_arm.inline.hpp
+++ b/src/hotspot/cpu/arm/smallRegisterMap_arm.inline.hpp
@@ -30,8 +30,15 @@
 
 // Java frames don't have callee saved registers (except for rfp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
 private:
   static void assert_is_rfp(VMReg r) NOT_DEBUG_RETURN
                                      DEBUG_ONLY({ Unimplemented(); })
@@ -46,12 +53,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-    Unimplemented();
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     Unimplemented();
     return nullptr;
diff --git a/src/hotspot/cpu/ppc/gc/shenandoah/c1/shenandoahBarrierSetC1_ppc.cpp b/src/hotspot/cpu/ppc/gc/shenandoah/c1/shenandoahBarrierSetC1_ppc.cpp
index 6d9a1db1ed4..5f87281bdf9 100644
--- a/src/hotspot/cpu/ppc/gc/shenandoah/c1/shenandoahBarrierSetC1_ppc.cpp
+++ b/src/hotspot/cpu/ppc/gc/shenandoah/c1/shenandoahBarrierSetC1_ppc.cpp
@@ -43,11 +43,6 @@ void LIR_OpShenandoahCompareAndSwap::emit_code(LIR_Assembler *masm) {
   Register tmp2 = _tmp2->as_register();
   Register result = result_opr()->as_register();
 
-  if (ShenandoahIUBarrier) {
-    ShenandoahBarrierSet::assembler()->iu_barrier(masm->masm(), new_val, tmp1, tmp2,
-                                                  MacroAssembler::PRESERVATION_FRAME_LR_GP_FP_REGS);
-  }
-
   if (UseCompressedOops) {
     __ encode_heap_oop(cmp_val, cmp_val);
     __ encode_heap_oop(new_val, new_val);
@@ -122,10 +117,6 @@ LIR_Opr ShenandoahBarrierSetC1::atomic_xchg_at_resolved(LIRAccess &access, LIRIt
   value.load_item();
   LIR_Opr value_opr = value.result();
 
-  if (access.is_oop()) {
-    value_opr = iu_barrier(access.gen(), value_opr, access.access_emit_info(), access.decorators());
-  }
-
   assert(type == T_INT || is_reference_type(type) LP64_ONLY( || type == T_LONG ), "unexpected type");
   LIR_Opr tmp_xchg = gen->new_register(T_INT);
   __ xchg(access.resolved_addr(), value_opr, result, tmp_xchg);
diff --git a/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp b/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp
index 535fe88a680..62aa9a2bf59 100644
--- a/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp
+++ b/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp
@@ -61,20 +61,6 @@ void ShenandoahBarrierSetAssembler::satb_write_barrier(MacroAssembler *masm,
   }
 }
 
-void ShenandoahBarrierSetAssembler::iu_barrier(MacroAssembler *masm,
-                                               Register val,
-                                               Register tmp1, Register tmp2,
-                                               MacroAssembler::PreservationLevel preservation_level,
-                                               DecoratorSet decorators) {
-  // IU barriers are also employed to avoid resurrection of weak references,
-  // even if Shenandoah does not operate in incremental update mode.
-  if (ShenandoahIUBarrier || ShenandoahSATBBarrier) {
-    __ block_comment("iu_barrier (shenandoahgc) {");
-    satb_write_barrier_impl(masm, decorators, noreg, noreg, val, tmp1, tmp2, preservation_level);
-    __ block_comment("} iu_barrier (shenandoahgc)");
-  }
-}
-
 void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler *masm, DecoratorSet decorators,
                                                            Register base, RegisterOrConstant ind_or_offs,
                                                            Register dst,
@@ -110,7 +96,7 @@ void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler *masm, Dec
 
   // Fast path: No barrier required if for every barrier type, it is either disabled or would not store
   // any useful information.
-  if ((!ShenandoahSATBBarrier || dest_uninitialized) && !ShenandoahIUBarrier && !ShenandoahLoadRefBarrier) {
+  if ((!ShenandoahSATBBarrier || dest_uninitialized) && !ShenandoahLoadRefBarrier) {
     return;
   }
 
@@ -582,7 +568,11 @@ void ShenandoahBarrierSetAssembler::load_at(
 
   /* ==== Apply keep-alive barrier, if required (e.g., to inhibit weak reference resurrection) ==== */
   if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
-    iu_barrier(masm, dst, tmp1, tmp2, preservation_level);
+    if (ShenandoahSATBBarrier) {
+      __ block_comment("keep_alive_barrier (shenandoahgc) {");
+      satb_write_barrier_impl(masm, 0, noreg, noreg, dst, tmp1, tmp2, preservation_level);
+      __ block_comment("} keep_alive_barrier (shenandoahgc)");
+    }
   }
 }
 
@@ -597,10 +587,6 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler *masm, DecoratorSet
     if (ShenandoahSATBBarrier) {
       satb_write_barrier(masm, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
     }
-
-    if (ShenandoahIUBarrier && val != noreg) {
-      iu_barrier(masm, val, tmp1, tmp2, preservation_level, decorators);
-    }
   }
 
   BarrierSetAssembler::store_at(masm, decorators, type,
diff --git a/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.hpp b/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.hpp
index 4514f2540ac..2e56187c169 100644
--- a/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.hpp
+++ b/src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.hpp
@@ -82,11 +82,6 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
                           Register tmp1, Register tmp2, Register tmp3,
                           MacroAssembler::PreservationLevel preservation_level);
 
-  void iu_barrier(MacroAssembler* masm,
-                        Register val,
-                        Register tmp1, Register tmp2,
-                        MacroAssembler::PreservationLevel preservation_level, DecoratorSet decorators = 0);
-
   void load_reference_barrier(MacroAssembler* masm, DecoratorSet decorators,
                               Register base, RegisterOrConstant ind_or_offs,
                               Register dst,
diff --git a/src/hotspot/cpu/ppc/smallRegisterMap_ppc.inline.hpp b/src/hotspot/cpu/ppc/smallRegisterMap_ppc.inline.hpp
index 8c96f51fd88..a6246cd7e74 100644
--- a/src/hotspot/cpu/ppc/smallRegisterMap_ppc.inline.hpp
+++ b/src/hotspot/cpu/ppc/smallRegisterMap_ppc.inline.hpp
@@ -30,9 +30,16 @@
 
 // Java frames don't have callee saved registers, so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
-public:
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
+
   // as_RegisterMap is used when we didn't want to templatize and abstract over RegisterMap type to support SmallRegisterMap
   // Consider enhancing SmallRegisterMap to support those cases
   const RegisterMap* as_RegisterMap() const { return nullptr; }
@@ -44,19 +51,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-#ifdef ASSERT
-  for(int i = 0; i < RegisterMap::reg_count; i++) {
-    VMReg r = VMRegImpl::as_VMReg(i);
-    if (map->location(r, (intptr_t*)nullptr) != nullptr) {
-      assert(false, "Reg: %s", r->name()); // Should not reach here
-    }
-  }
-#endif
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     assert(false, "Reg: %s", reg->name());
     return nullptr;
diff --git a/src/hotspot/cpu/riscv/gc/shenandoah/c1/shenandoahBarrierSetC1_riscv.cpp b/src/hotspot/cpu/riscv/gc/shenandoah/c1/shenandoahBarrierSetC1_riscv.cpp
index cd568cc723f..f503cb762e7 100644
--- a/src/hotspot/cpu/riscv/gc/shenandoah/c1/shenandoahBarrierSetC1_riscv.cpp
+++ b/src/hotspot/cpu/riscv/gc/shenandoah/c1/shenandoahBarrierSetC1_riscv.cpp
@@ -41,8 +41,6 @@ void LIR_OpShenandoahCompareAndSwap::emit_code(LIR_Assembler* masm) {
   Register tmp2 = _tmp2->as_register();
   Register result = result_opr()->as_register();
 
-  ShenandoahBarrierSet::assembler()->iu_barrier(masm->masm(), newval, t1);
-
   if (UseCompressedOops) {
     __ encode_heap_oop(tmp1, cmpval);
     cmpval = tmp1;
@@ -94,10 +92,6 @@ LIR_Opr ShenandoahBarrierSetC1::atomic_xchg_at_resolved(LIRAccess& access, LIRIt
   value.load_item();
   LIR_Opr value_opr = value.result();
 
-  if (access.is_oop()) {
-    value_opr = iu_barrier(access.gen(), value_opr, access.access_emit_info(), access.decorators());
-  }
-
   assert(type == T_INT || is_reference_type(type) LP64_ONLY( || type == T_LONG ), "unexpected type");
   LIR_Opr tmp = gen->new_register(T_INT);
   __ xchg(access.resolved_addr(), value_opr, result, tmp);
diff --git a/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.cpp b/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.cpp
index 9be8259e7e8..9a79a923277 100644
--- a/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.cpp
+++ b/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.cpp
@@ -48,7 +48,7 @@ void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, Dec
                                                        Register src, Register dst, Register count, RegSet saved_regs) {
   if (is_oop) {
     bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
-    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahIUBarrier || ShenandoahLoadRefBarrier) {
+    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahLoadRefBarrier) {
 
       Label done;
 
@@ -308,16 +308,6 @@ void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm,
   __ leave();
 }
 
-void ShenandoahBarrierSetAssembler::iu_barrier(MacroAssembler* masm, Register dst, Register tmp) {
-  if (ShenandoahIUBarrier) {
-    __ push_call_clobbered_registers();
-
-    satb_write_barrier_pre(masm, noreg, dst, xthread, tmp, t0, true, false);
-
-    __ pop_call_clobbered_registers();
-  }
-}
-
 //
 // Arguments:
 //
@@ -420,8 +410,7 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet
   if (val == noreg) {
     BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), noreg, noreg, noreg, noreg);
   } else {
-    iu_barrier(masm, val, tmp1);
-    // G1 barrier needs uncompressed oop for region cross check.
+    // Barrier needs uncompressed oop for region cross check.
     Register new_val = val;
     if (UseCompressedOops) {
       new_val = t1;
diff --git a/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.hpp b/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.hpp
index 0ae352f325d..bfdea7f607e 100644
--- a/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.hpp
+++ b/src/hotspot/cpu/riscv/gc/shenandoah/shenandoahBarrierSetAssembler_riscv.hpp
@@ -63,8 +63,6 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
 
 public:
 
-  void iu_barrier(MacroAssembler* masm, Register dst, Register tmp);
-
   virtual NMethodPatchingType nmethod_patching_type() { return NMethodPatchingType::conc_data_patch; }
 
 #ifdef COMPILER1
diff --git a/src/hotspot/cpu/riscv/smallRegisterMap_riscv.inline.hpp b/src/hotspot/cpu/riscv/smallRegisterMap_riscv.inline.hpp
index 93adaadcef6..9fc4f1d7b0a 100644
--- a/src/hotspot/cpu/riscv/smallRegisterMap_riscv.inline.hpp
+++ b/src/hotspot/cpu/riscv/smallRegisterMap_riscv.inline.hpp
@@ -30,8 +30,15 @@
 
 // Java frames don't have callee saved registers (except for fp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
 private:
   static void assert_is_fp(VMReg r) NOT_DEBUG_RETURN
                                     DEBUG_ONLY({ assert (r == fp->as_VMReg() || r == fp->as_VMReg()->next(), "Reg: %s", r->name()); })
@@ -48,17 +55,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-  #ifdef ASSERT
-    for(int i = 0; i < RegisterMap::reg_count; i++) {
-      VMReg r = VMRegImpl::as_VMReg(i);
-      if (map->location(r, (intptr_t*)nullptr) != nullptr) assert_is_fp(r);
-    }
-  #endif
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     assert_is_fp(reg);
     return (address)(sp - 2);
diff --git a/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp b/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
index 2a9faee7e2f..f78d7261e40 100644
--- a/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
+++ b/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
@@ -5936,7 +5936,6 @@ static const int64_t right_3_bits = right_n_bits(3);
   }
 
   void generate_compiler_stubs() {
-#if COMPILER2_OR_JVMCI
 #ifdef COMPILER2
     if (UseMulAddIntrinsic) {
       StubRoutines::_mulAdd = generate_mulAdd();
@@ -5970,7 +5969,6 @@ static const int64_t right_3_bits = right_n_bits(3);
       StubRoutines::_bigIntegerLeftShiftWorker = generate_bigIntegerLeftShift();
       StubRoutines::_bigIntegerRightShiftWorker = generate_bigIntegerRightShift();
     }
-#endif // COMPILER2
 
     if (UseSHA256Intrinsics) {
       Sha2Generator sha2(_masm, this);
@@ -5984,10 +5982,6 @@ static const int64_t right_3_bits = right_n_bits(3);
       StubRoutines::_sha512_implCompressMB = sha2.generate_sha512_implCompress(true);
     }
 
-    generate_compare_long_strings();
-
-    generate_string_indexof_stubs();
-
     if (UseMD5Intrinsics) {
       StubRoutines::_md5_implCompress   = generate_md5_implCompress(false, "md5_implCompress");
       StubRoutines::_md5_implCompressMB = generate_md5_implCompress(true,  "md5_implCompressMB");
@@ -6006,7 +6000,11 @@ static const int64_t right_3_bits = right_n_bits(3);
       StubRoutines::_updateBytesAdler32 = generate_updateBytesAdler32();
     }
 
-#endif // COMPILER2_OR_JVMCI
+    generate_compare_long_strings();
+
+    generate_string_indexof_stubs();
+
+#endif // COMPILER2
   }
 
  public:
diff --git a/src/hotspot/cpu/riscv/vm_version_riscv.cpp b/src/hotspot/cpu/riscv/vm_version_riscv.cpp
index c52c809f935..ac2d6cde1a2 100644
--- a/src/hotspot/cpu/riscv/vm_version_riscv.cpp
+++ b/src/hotspot/cpu/riscv/vm_version_riscv.cpp
@@ -58,6 +58,13 @@ void VM_Version::useRVA23U64Profile() {
 }
 
 void VM_Version::initialize() {
+  common_initialize();
+#ifdef COMPILER2
+  c2_initialize();
+#endif // COMPILER2
+}
+
+void VM_Version::common_initialize() {
   _supports_atomic_getset4 = true;
   _supports_atomic_getadd4 = true;
   _supports_atomic_getset8 = true;
@@ -152,10 +159,6 @@ void VM_Version::initialize() {
     FLAG_SET_DEFAULT(UseVectorizedMismatchIntrinsic, false);
   }
 
-  if (FLAG_IS_DEFAULT(UseMD5Intrinsics)) {
-    FLAG_SET_DEFAULT(UseMD5Intrinsics, true);
-  }
-
   if (FLAG_IS_DEFAULT(UsePoly1305Intrinsics)) {
     FLAG_SET_DEFAULT(UsePoly1305Intrinsics, true);
   }
@@ -230,15 +233,105 @@ void VM_Version::initialize() {
       _initial_vector_length = cpu_vector_length();
     }
   }
+}
 
 #ifdef COMPILER2
-  c2_initialize();
-#endif // COMPILER2
+void VM_Version::c2_initialize() {
+  if (UseCMoveUnconditionally) {
+    FLAG_SET_DEFAULT(UseCMoveUnconditionally, false);
+  }
+
+  if (ConditionalMoveLimit > 0) {
+    FLAG_SET_DEFAULT(ConditionalMoveLimit, 0);
+  }
 
-  // NOTE: Make sure codes dependent on UseRVV are put after c2_initialize(),
+  if (!UseRVV) {
+    FLAG_SET_DEFAULT(MaxVectorSize, 0);
+    FLAG_SET_DEFAULT(UseRVVForBigIntegerShiftIntrinsics, false);
+  } else {
+    if (!FLAG_IS_DEFAULT(MaxVectorSize) && MaxVectorSize != _initial_vector_length) {
+      warning("Current system does not support RVV vector length for MaxVectorSize %d. Set MaxVectorSize to %d",
+               (int)MaxVectorSize, _initial_vector_length);
+    }
+    MaxVectorSize = _initial_vector_length;
+    if (MaxVectorSize < 16) {
+      warning("RVV does not support vector length less than 16 bytes. Disabling RVV.");
+      UseRVV = false;
+      FLAG_SET_DEFAULT(MaxVectorSize, 0);
+    }
+  }
+
+  // NOTE: Make sure codes dependent on UseRVV are put after MaxVectorSize initialize,
   //       as there are extra checks inside it which could disable UseRVV
   //       in some situations.
 
+  if (FLAG_IS_DEFAULT(UseVectorizedHashCodeIntrinsic)) {
+    FLAG_SET_DEFAULT(UseVectorizedHashCodeIntrinsic, true);
+  }
+
+  if (!UseZicbop) {
+    if (!FLAG_IS_DEFAULT(AllocatePrefetchStyle)) {
+      warning("Zicbop is not available on this CPU");
+    }
+    FLAG_SET_DEFAULT(AllocatePrefetchStyle, 0);
+  } else {
+    // Limit AllocatePrefetchDistance so that it does not exceed the
+    // static constraint of 512 defined in runtime/globals.hpp.
+    if (FLAG_IS_DEFAULT(AllocatePrefetchDistance)) {
+      FLAG_SET_DEFAULT(AllocatePrefetchDistance, MIN2(512, 3 * (int)CacheLineSize));
+    }
+    if (FLAG_IS_DEFAULT(AllocatePrefetchStepSize)) {
+      FLAG_SET_DEFAULT(AllocatePrefetchStepSize, (int)CacheLineSize);
+    }
+    if (FLAG_IS_DEFAULT(PrefetchScanIntervalInBytes)) {
+      FLAG_SET_DEFAULT(PrefetchScanIntervalInBytes, 3 * (int)CacheLineSize);
+    }
+    if (FLAG_IS_DEFAULT(PrefetchCopyIntervalInBytes)) {
+      FLAG_SET_DEFAULT(PrefetchCopyIntervalInBytes, 3 * (int)CacheLineSize);
+    }
+
+    if (PrefetchCopyIntervalInBytes != -1 &&
+        ((PrefetchCopyIntervalInBytes & 7) || (PrefetchCopyIntervalInBytes >= 32768))) {
+      warning("PrefetchCopyIntervalInBytes must be -1, or a multiple of 8 and < 32768");
+      PrefetchCopyIntervalInBytes &= ~7;
+      if (PrefetchCopyIntervalInBytes >= 32768) {
+        PrefetchCopyIntervalInBytes = 32760;
+      }
+    }
+    if (AllocatePrefetchDistance !=-1 && (AllocatePrefetchDistance & 7)) {
+      warning("AllocatePrefetchDistance must be multiple of 8");
+      AllocatePrefetchDistance &= ~7;
+    }
+    if (AllocatePrefetchStepSize & 7) {
+      warning("AllocatePrefetchStepSize must be multiple of 8");
+      AllocatePrefetchStepSize &= ~7;
+    }
+  }
+
+  if (FLAG_IS_DEFAULT(UseMulAddIntrinsic)) {
+    FLAG_SET_DEFAULT(UseMulAddIntrinsic, true);
+  }
+
+  if (FLAG_IS_DEFAULT(UseMultiplyToLenIntrinsic)) {
+    FLAG_SET_DEFAULT(UseMultiplyToLenIntrinsic, true);
+  }
+
+  if (FLAG_IS_DEFAULT(UseSquareToLenIntrinsic)) {
+    FLAG_SET_DEFAULT(UseSquareToLenIntrinsic, true);
+  }
+
+  if (FLAG_IS_DEFAULT(UseMontgomeryMultiplyIntrinsic)) {
+    FLAG_SET_DEFAULT(UseMontgomeryMultiplyIntrinsic, true);
+  }
+
+  if (FLAG_IS_DEFAULT(UseMontgomerySquareIntrinsic)) {
+    FLAG_SET_DEFAULT(UseMontgomerySquareIntrinsic, true);
+  }
+
+  if (FLAG_IS_DEFAULT(UseMD5Intrinsics)) {
+    FLAG_SET_DEFAULT(UseMD5Intrinsics, true);
+  }
+
   // Adler32
   if (UseRVV) {
     if (FLAG_IS_DEFAULT(UseAdler32Intrinsics)) {
@@ -252,7 +345,9 @@ void VM_Version::initialize() {
   }
 
   // ChaCha20
-  if (UseRVV) {
+  if (UseRVV && MaxVectorSize >= 32) {
+    // performance tests on hardwares (MaxVectorSize == 16, 32) show that
+    // it brings regression when MaxVectorSize == 16.
     if (FLAG_IS_DEFAULT(UseChaCha20Intrinsics)) {
       FLAG_SET_DEFAULT(UseChaCha20Intrinsics, true);
     }
@@ -330,96 +425,6 @@ void VM_Version::initialize() {
     FLAG_SET_DEFAULT(UseSHA, false);
   }
 }
-
-#ifdef COMPILER2
-void VM_Version::c2_initialize() {
-  if (UseCMoveUnconditionally) {
-    FLAG_SET_DEFAULT(UseCMoveUnconditionally, false);
-  }
-
-  if (ConditionalMoveLimit > 0) {
-    FLAG_SET_DEFAULT(ConditionalMoveLimit, 0);
-  }
-
-  if (!UseRVV) {
-    FLAG_SET_DEFAULT(MaxVectorSize, 0);
-    FLAG_SET_DEFAULT(UseRVVForBigIntegerShiftIntrinsics, false);
-  } else {
-    if (!FLAG_IS_DEFAULT(MaxVectorSize) && MaxVectorSize != _initial_vector_length) {
-      warning("Current system does not support RVV vector length for MaxVectorSize %d. Set MaxVectorSize to %d",
-               (int)MaxVectorSize, _initial_vector_length);
-    }
-    MaxVectorSize = _initial_vector_length;
-    if (MaxVectorSize < 16) {
-      warning("RVV does not support vector length less than 16 bytes. Disabling RVV.");
-      UseRVV = false;
-      FLAG_SET_DEFAULT(MaxVectorSize, 0);
-    }
-  }
-
-  if (FLAG_IS_DEFAULT(UseVectorizedHashCodeIntrinsic)) {
-    FLAG_SET_DEFAULT(UseVectorizedHashCodeIntrinsic, true);
-  }
-
-  if (!UseZicbop) {
-    if (!FLAG_IS_DEFAULT(AllocatePrefetchStyle)) {
-      warning("Zicbop is not available on this CPU");
-    }
-    FLAG_SET_DEFAULT(AllocatePrefetchStyle, 0);
-  } else {
-    // Limit AllocatePrefetchDistance so that it does not exceed the
-    // static constraint of 512 defined in runtime/globals.hpp.
-    if (FLAG_IS_DEFAULT(AllocatePrefetchDistance)) {
-      FLAG_SET_DEFAULT(AllocatePrefetchDistance, MIN2(512, 3 * (int)CacheLineSize));
-    }
-    if (FLAG_IS_DEFAULT(AllocatePrefetchStepSize)) {
-      FLAG_SET_DEFAULT(AllocatePrefetchStepSize, (int)CacheLineSize);
-    }
-    if (FLAG_IS_DEFAULT(PrefetchScanIntervalInBytes)) {
-      FLAG_SET_DEFAULT(PrefetchScanIntervalInBytes, 3 * (int)CacheLineSize);
-    }
-    if (FLAG_IS_DEFAULT(PrefetchCopyIntervalInBytes)) {
-      FLAG_SET_DEFAULT(PrefetchCopyIntervalInBytes, 3 * (int)CacheLineSize);
-    }
-
-    if (PrefetchCopyIntervalInBytes != -1 &&
-        ((PrefetchCopyIntervalInBytes & 7) || (PrefetchCopyIntervalInBytes >= 32768))) {
-      warning("PrefetchCopyIntervalInBytes must be -1, or a multiple of 8 and < 32768");
-      PrefetchCopyIntervalInBytes &= ~7;
-      if (PrefetchCopyIntervalInBytes >= 32768) {
-        PrefetchCopyIntervalInBytes = 32760;
-      }
-    }
-    if (AllocatePrefetchDistance !=-1 && (AllocatePrefetchDistance & 7)) {
-      warning("AllocatePrefetchDistance must be multiple of 8");
-      AllocatePrefetchDistance &= ~7;
-    }
-    if (AllocatePrefetchStepSize & 7) {
-      warning("AllocatePrefetchStepSize must be multiple of 8");
-      AllocatePrefetchStepSize &= ~7;
-    }
-  }
-
-  if (FLAG_IS_DEFAULT(UseMulAddIntrinsic)) {
-    FLAG_SET_DEFAULT(UseMulAddIntrinsic, true);
-  }
-
-  if (FLAG_IS_DEFAULT(UseMultiplyToLenIntrinsic)) {
-    FLAG_SET_DEFAULT(UseMultiplyToLenIntrinsic, true);
-  }
-
-  if (FLAG_IS_DEFAULT(UseSquareToLenIntrinsic)) {
-    FLAG_SET_DEFAULT(UseSquareToLenIntrinsic, true);
-  }
-
-  if (FLAG_IS_DEFAULT(UseMontgomeryMultiplyIntrinsic)) {
-    FLAG_SET_DEFAULT(UseMontgomeryMultiplyIntrinsic, true);
-  }
-
-  if (FLAG_IS_DEFAULT(UseMontgomerySquareIntrinsic)) {
-    FLAG_SET_DEFAULT(UseMontgomerySquareIntrinsic, true);
-  }
-}
 #endif // COMPILER2
 
 void VM_Version::initialize_cpu_information(void) {
diff --git a/src/hotspot/cpu/riscv/vm_version_riscv.hpp b/src/hotspot/cpu/riscv/vm_version_riscv.hpp
index 9556e2dc9ad..bd4bfe86d9b 100644
--- a/src/hotspot/cpu/riscv/vm_version_riscv.hpp
+++ b/src/hotspot/cpu/riscv/vm_version_riscv.hpp
@@ -264,6 +264,8 @@ class VM_Version : public Abstract_VM_Version {
   static uint32_t cpu_vector_length();
   static uint32_t _initial_vector_length;
 
+  static void common_initialize();
+
 #ifdef COMPILER2
   static void c2_initialize();
 #endif // COMPILER2
diff --git a/src/hotspot/cpu/s390/macroAssembler_s390.cpp b/src/hotspot/cpu/s390/macroAssembler_s390.cpp
index 66d6f25f0fd..72d10ee80aa 100644
--- a/src/hotspot/cpu/s390/macroAssembler_s390.cpp
+++ b/src/hotspot/cpu/s390/macroAssembler_s390.cpp
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2016, 2024 SAP SE. All rights reserved.
+ * Copyright 2024 IBM Corporation. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -3152,6 +3153,301 @@ void MacroAssembler::check_klass_subtype(Register sub_klass,
   BLOCK_COMMENT("} check_klass_subtype");
 }
 
+// scans r_count pointer sized words at [r_addr] for occurrence of r_value,
+// generic (r_count must be >0)
+// iff found: CC eq, r_result == 0
+void MacroAssembler::repne_scan(Register r_addr, Register r_value, Register r_count, Register r_result) {
+  NearLabel L_loop, L_exit;
+
+  BLOCK_COMMENT("repne_scan {");
+#ifdef ASSERT
+  z_chi(r_count, 0);
+  asm_assert(bcondHigh, "count must be positive", 11);
+#endif
+
+  clear_reg(r_result, true /* whole_reg */, false /* set_cc */);  // sets r_result=0, let's hope that search will be successful
+
+  bind(L_loop);
+  z_cg(r_value, Address(r_addr));
+  z_bre(L_exit); // branch on success
+  z_la(r_addr, wordSize, r_addr);
+  z_brct(r_count, L_loop);
+
+  // z_brct above doesn't change CC.
+  // If we reach here, then the value in r_value is not present. Set r_result to 1.
+  z_lghi(r_result, 1);
+
+  bind(L_exit);
+  BLOCK_COMMENT("} repne_scan");
+}
+
+// Ensure that the inline code and the stub are using the same registers.
+#define LOOKUP_SECONDARY_SUPERS_TABLE_REGISTERS                 \
+do {                                                            \
+  assert(r_super_klass  == Z_ARG1                            && \
+         r_array_base   == Z_ARG5                            && \
+         r_array_length == Z_ARG4                            && \
+        (r_array_index  == Z_ARG3 || r_array_index == noreg) && \
+        (r_sub_klass    == Z_ARG2 || r_sub_klass   == noreg) && \
+        (r_bitmap       == Z_R10  || r_bitmap      == noreg) && \
+        (r_result       == Z_R11  || r_result      == noreg), "registers must match s390.ad"); \
+} while(0)
+
+// Note: this method also kills Z_R1_scratch register on machines older than z15
+void MacroAssembler::lookup_secondary_supers_table(Register r_sub_klass,
+                                                   Register r_super_klass,
+                                                   Register r_temp1,
+                                                   Register r_temp2,
+                                                   Register r_temp3,
+                                                   Register r_temp4,
+                                                   Register r_result,
+                                                   u1 super_klass_slot) {
+  NearLabel L_done, L_failure;
+
+  BLOCK_COMMENT("lookup_secondary_supers_table {");
+
+  const Register
+    r_array_base   = r_temp1,
+    r_array_length = r_temp2,
+    r_array_index  = r_temp3,
+    r_bitmap       = r_temp4;
+
+  LOOKUP_SECONDARY_SUPERS_TABLE_REGISTERS;
+
+  z_lg(r_bitmap, Address(r_sub_klass, Klass::bitmap_offset()));
+
+  // First check the bitmap to see if super_klass might be present. If
+  // the bit is zero, we are certain that super_klass is not one of
+  // the secondary supers.
+  u1 bit = super_klass_slot;
+  int shift_count = Klass::SECONDARY_SUPERS_TABLE_MASK - bit;
+
+  z_sllg(r_array_index, r_bitmap, shift_count); // take the bit to 63rd location
+
+  // Initialize r_result with 0 (indicating success). If searching fails, r_result will be loaded
+  // with 1 (failure) at the end of this method.
+  clear_reg(r_result, true /* whole_reg */, false /* set_cc */); // r_result = 0
+
+  // We test the MSB of r_array_index, i.e., its sign bit
+  testbit(r_array_index, 63);
+  z_bfalse(L_failure); // if not set, then jump!!!
+
+  // We will consult the secondary-super array.
+  z_lg(r_array_base, Address(r_sub_klass, Klass::secondary_supers_offset()));
+
+  // The value i in r_array_index is >= 1, so even though r_array_base
+  // points to the length, we don't need to adjust it to point to the
+  // data.
+  assert(Array<Klass*>::base_offset_in_bytes() == wordSize, "Adjust this code");
+
+  // Get the first array index that can contain super_klass.
+  if (bit != 0) {
+    pop_count_long(r_array_index, r_array_index, Z_R1_scratch); // kills Z_R1_scratch on machines older than z15
+
+    // NB! r_array_index is off by 1. It is compensated by keeping r_array_base off by 1 word.
+    z_sllg(r_array_index, r_array_index, LogBytesPerWord); // scale
+  } else {
+    // Actually use index 0, but r_array_base and r_array_index are off by 1 word
+    // such that the sum is precise.
+    z_lghi(r_array_index, BytesPerWord); // for slow path (scaled)
+  }
+
+  z_cg(r_super_klass, Address(r_array_base, r_array_index));
+  branch_optimized(bcondEqual, L_done); // found a match; success
+
+  // Is there another entry to check? Consult the bitmap.
+  testbit(r_bitmap, (bit + 1) & Klass::SECONDARY_SUPERS_TABLE_MASK);
+  z_bfalse(L_failure);
+
+  // Linear probe. Rotate the bitmap so that the next bit to test is
+  // in Bit 2 for the look-ahead check in the slow path.
+  if (bit != 0) {
+    z_rllg(r_bitmap, r_bitmap, 64-bit); // rotate right
+  }
+
+  // Calls into the stub generated by lookup_secondary_supers_table_slow_path.
+  // Arguments: r_super_klass, r_array_base, r_array_index, r_bitmap.
+  // Kills: r_array_length.
+  // Returns: r_result
+
+  call_stub(StubRoutines::lookup_secondary_supers_table_slow_path_stub());
+
+  z_bru(L_done); // pass whatever result we got from a slow path
+
+  bind(L_failure);
+  // TODO: use load immediate on condition and z_bru above will not be required
+  z_lghi(r_result, 1);
+
+  bind(L_done);
+  BLOCK_COMMENT("} lookup_secondary_supers_table");
+
+  if (VerifySecondarySupers) {
+    verify_secondary_supers_table(r_sub_klass, r_super_klass, r_result,
+                                  r_temp1, r_temp2, r_temp3);
+  }
+}
+
+// Called by code generated by check_klass_subtype_slow_path
+// above. This is called when there is a collision in the hashed
+// lookup in the secondary supers array.
+void MacroAssembler::lookup_secondary_supers_table_slow_path(Register r_super_klass,
+                                                             Register r_array_base,
+                                                             Register r_array_index,
+                                                             Register r_bitmap,
+                                                             Register r_result,
+                                                             Register r_temp1) {
+  assert_different_registers(r_super_klass, r_array_base, r_array_index, r_bitmap, r_result, r_temp1);
+
+  const Register
+    r_array_length = r_temp1,
+    r_sub_klass    = noreg;
+
+  LOOKUP_SECONDARY_SUPERS_TABLE_REGISTERS;
+
+  BLOCK_COMMENT("lookup_secondary_supers_table_slow_path {");
+  NearLabel L_done, L_failure;
+
+  // Load the array length.
+  z_llgf(r_array_length, Address(r_array_base, Array<Klass*>::length_offset_in_bytes()));
+
+  // And adjust the array base to point to the data.
+  // NB!
+  // Effectively increments the current slot index by 1.
+  assert(Array<Klass*>::base_offset_in_bytes() == wordSize, "");
+  add2reg(r_array_base, Array<Klass*>::base_offset_in_bytes());
+
+  // Linear probe
+  NearLabel L_huge;
+
+  // The bitmap is full to bursting.
+  z_cghi(r_bitmap, Klass::SECONDARY_SUPERS_BITMAP_FULL);
+  z_bre(L_huge);
+
+  // NB! Our caller has checked bits 0 and 1 in the bitmap. The
+  // current slot (at secondary_supers[r_array_index]) has not yet
+  // been inspected, and r_array_index may be out of bounds if we
+  // wrapped around the end of the array.
+
+  { // This is conventional linear probing, but instead of terminating
+    // when a null entry is found in the table, we maintain a bitmap
+    // in which a 0 indicates missing entries.
+    // The check above guarantees there are 0s in the bitmap, so the loop
+    // eventually terminates.
+
+#ifdef ASSERT
+    // r_result is set to 0 by lookup_secondary_supers_table.
+    // clear_reg(r_result, true /* whole_reg */, false /* set_cc */);
+    z_cghi(r_result, 0);
+    asm_assert(bcondEqual, "r_result required to be 0, used by z_locgr", 44);
+
+    // We should only reach here after having found a bit in the bitmap.
+    z_ltgr(r_array_length, r_array_length);
+    asm_assert(bcondHigh, "array_length > 0, should hold", 22);
+#endif // ASSERT
+
+    // Compute limit in r_array_length
+    add2reg(r_array_length, -1);
+    z_sllg(r_array_length, r_array_length, LogBytesPerWord);
+
+    NearLabel L_loop;
+    bind(L_loop);
+
+    // Check for wraparound.
+    z_cgr(r_array_index, r_array_length);
+    z_locgr(r_array_index, r_result, bcondHigh); // r_result is containing 0
+
+    z_cg(r_super_klass, Address(r_array_base, r_array_index));
+    z_bre(L_done); // success
+
+    // look-ahead check: if Bit 2 is 0, we're done
+    testbit(r_bitmap, 2);
+    z_bfalse(L_failure);
+
+    z_rllg(r_bitmap, r_bitmap, 64-1); // rotate right
+    add2reg(r_array_index, BytesPerWord);
+
+    z_bru(L_loop);
+  }
+
+  { // Degenerate case: more than 64 secondary supers.
+    // FIXME: We could do something smarter here, maybe a vectorized
+    // comparison or a binary search, but is that worth any added
+    // complexity?
+
+    bind(L_huge);
+    repne_scan(r_array_base, r_super_klass, r_array_length, r_result);
+
+    z_bru(L_done); // forward the result we got from repne_scan
+  }
+
+  bind(L_failure);
+  z_lghi(r_result, 1);
+
+  bind(L_done);
+  BLOCK_COMMENT("} lookup_secondary_supers_table_slow_path");
+}
+
+// Make sure that the hashed lookup and a linear scan agree.
+void MacroAssembler::verify_secondary_supers_table(Register r_sub_klass,
+                                                   Register r_super_klass,
+                                                   Register r_result /* expected */,
+                                                   Register r_temp1,
+                                                   Register r_temp2,
+                                                   Register r_temp3) {
+  assert_different_registers(r_sub_klass, r_super_klass, r_result, r_temp1, r_temp2, r_temp3);
+
+  const Register
+    r_array_base   = r_temp1,
+    r_array_length = r_temp2,
+    r_array_index  = r_temp3,
+    r_bitmap       = noreg; // unused
+
+  const Register r_one = Z_R0_scratch;
+  z_lghi(r_one, 1); // for locgr down there, to a load result for failure
+
+  LOOKUP_SECONDARY_SUPERS_TABLE_REGISTERS;
+
+  BLOCK_COMMENT("verify_secondary_supers_table {");
+
+  Label L_passed, L_failure;
+
+  // We will consult the secondary-super array.
+  z_lg(r_array_base, Address(r_sub_klass, in_bytes(Klass::secondary_supers_offset())));
+
+  // Load the array length.
+  z_llgf(r_array_length, Address(r_array_base, Array<Klass*>::length_offset_in_bytes()));
+
+  // And adjust the array base to point to the data.
+  z_aghi(r_array_base, Array<Klass*>::base_offset_in_bytes());
+
+  const Register r_linear_result = r_array_index; // reuse
+  z_chi(r_array_length, 0);
+  z_locgr(r_linear_result, r_one, bcondNotHigh); // load failure if array_length <= 0
+  z_brc(bcondNotHigh, L_failure);
+  repne_scan(r_array_base, r_super_klass, r_array_length, r_linear_result);
+  bind(L_failure);
+
+  z_cr(r_result, r_linear_result);
+  z_bre(L_passed);
+
+  assert_different_registers(Z_ARG1, r_sub_klass, r_linear_result, r_result);
+  lgr_if_needed(Z_ARG1, r_super_klass);
+  assert_different_registers(Z_ARG2, r_linear_result, r_result);
+  lgr_if_needed(Z_ARG2, r_sub_klass);
+  assert_different_registers(Z_ARG3, r_result);
+  z_lgr(Z_ARG3, r_linear_result);
+  z_lgr(Z_ARG4, r_result);
+  const char* msg = "mismatch";
+  load_const_optimized(Z_ARG5, (address)msg);
+
+  call_VM_leaf(CAST_FROM_FN_PTR(address, Klass::on_secondary_supers_verification_failure));
+  should_not_reach_here();
+
+  bind(L_passed);
+
+  BLOCK_COMMENT("} verify_secondary_supers_table");
+}
+
 void MacroAssembler::clinit_barrier(Register klass, Register thread, Label* L_fast_path, Label* L_slow_path) {
   assert(L_fast_path != nullptr || L_slow_path != nullptr, "at least one is required");
 
diff --git a/src/hotspot/cpu/s390/macroAssembler_s390.hpp b/src/hotspot/cpu/s390/macroAssembler_s390.hpp
index 684741d79db..90210eb28c3 100644
--- a/src/hotspot/cpu/s390/macroAssembler_s390.hpp
+++ b/src/hotspot/cpu/s390/macroAssembler_s390.hpp
@@ -708,6 +708,31 @@ class MacroAssembler: public Assembler {
                                      Label* L_success,
                                      Label* L_failure);
 
+  void repne_scan(Register r_addr, Register r_value, Register r_count, Register r_scratch);
+
+  void lookup_secondary_supers_table(Register r_sub_klass,
+                                     Register r_super_klass,
+                                     Register r_temp1,
+                                     Register r_temp2,
+                                     Register r_temp3,
+                                     Register r_temp4,
+                                     Register r_result,
+                                     u1 super_klass_slot);
+
+  void lookup_secondary_supers_table_slow_path(Register r_super_klass,
+                                               Register r_array_base,
+                                               Register r_array_index,
+                                               Register r_bitmap,
+                                               Register r_result,
+                                               Register r_temp1);
+
+  void verify_secondary_supers_table(Register r_sub_klass,
+                                     Register r_super_klass,
+                                     Register r_result /* expected */,
+                                     Register r_temp1,
+                                     Register r_temp2,
+                                     Register r_temp3);
+
   // Simplified, combined version, good for typical uses.
   // Falls through on failure.
   void check_klass_subtype(Register sub_klass,
diff --git a/src/hotspot/cpu/s390/s390.ad b/src/hotspot/cpu/s390/s390.ad
index 0fe3840b9b5..e3dcfdb8759 100644
--- a/src/hotspot/cpu/s390/s390.ad
+++ b/src/hotspot/cpu/s390/s390.ad
@@ -356,6 +356,8 @@ reg_class z_rarg3_ptr_reg(Z_R4_H,Z_R4);
 reg_class z_rarg4_ptr_reg(Z_R5_H,Z_R5);
 reg_class z_rarg5_ptr_reg(Z_R6_H,Z_R6);
 reg_class z_thread_ptr_reg(Z_R8_H,Z_R8);
+reg_class z_r10_ptr_reg(Z_R10_H, Z_R10);
+reg_class z_r11_ptr_reg(Z_R11_H, Z_R11);
 
 reg_class z_ptr_reg(
 /*Z_R0_H,Z_R0*/     // R0
@@ -2985,6 +2987,8 @@ operand iRegP() %{
   match(rarg5RegP);
   match(revenRegP);
   match(roddRegP);
+  match(r10TempRegP);
+  match(r11TempRegP);
   format %{ %}
   interface(REG_INTER);
 %}
@@ -2997,6 +3001,20 @@ operand threadRegP() %{
   interface(REG_INTER);
 %}
 
+operand r10TempRegP() %{
+  constraint(ALLOC_IN_RC(z_r10_ptr_reg));
+  match(iRegP);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand r11TempRegP() %{
+  constraint(ALLOC_IN_RC(z_r11_ptr_reg));
+  match(iRegP);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
 operand noArg_iRegP() %{
   constraint(ALLOC_IN_RC(z_no_arg_ptr_reg));
   match(iRegP);
@@ -9560,6 +9578,32 @@ instruct partialSubtypeCheck(rarg1RegP index, rarg2RegP sub, rarg3RegP super, fl
   ins_pipe(pipe_class_dummy);
 %}
 
+instruct partialSubtypeCheckConstSuper(rarg2RegP sub, rarg1RegP super, immP super_con,
+                                       r11TempRegP result, rarg5RegP temp1, rarg4RegP temp2,
+                                       rarg3RegP temp3, r10TempRegP temp4, flagsReg pcc) %{
+  match(Set result (PartialSubtypeCheck sub (Binary super super_con)));
+  predicate(UseSecondarySupersTable);
+  effect(KILL pcc, TEMP temp1, TEMP temp2, TEMP temp3, TEMP temp4);
+  ins_cost(7 * DEFAULT_COST); // needs to be less than competing nodes
+  format %{ "partialSubtypeCheck $result, $sub, $super, $super_con" %}
+
+  ins_encode %{
+    u1 super_klass_slot = ((Klass*)$super_con$$constant)->hash_slot();
+    if (InlineSecondarySupersTest) {
+      __ lookup_secondary_supers_table($sub$$Register, $super$$Register,
+                                                 $temp1$$Register, $temp2$$Register, $temp3$$Register,
+                                                 $temp4$$Register, $result$$Register, super_klass_slot);
+    } else {
+      AddressLiteral stub_address(StubRoutines::lookup_secondary_supers_table_stub(super_klass_slot));
+      __ load_const_optimized(Z_ARG4, stub_address);
+      __ z_basr(Z_R14, Z_ARG4);
+    }
+
+  %}
+
+  ins_pipe(pipe_class_dummy);
+%}
+
 instruct partialSubtypeCheck_vs_zero(flagsReg pcc, rarg2RegP sub, rarg3RegP super, immP0 zero,
                                      rarg1RegP index, rarg4RegP scratch1, rarg5RegP scratch2) %{
   match(Set pcc (CmpI (PartialSubtypeCheck sub super) zero));
diff --git a/src/hotspot/cpu/s390/smallRegisterMap_s390.inline.hpp b/src/hotspot/cpu/s390/smallRegisterMap_s390.inline.hpp
index 8c74eb7dd6d..625d17cf992 100644
--- a/src/hotspot/cpu/s390/smallRegisterMap_s390.inline.hpp
+++ b/src/hotspot/cpu/s390/smallRegisterMap_s390.inline.hpp
@@ -30,8 +30,15 @@
 
 // Java frames don't have callee saved registers (except for rfp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
 private:
   static void assert_is_rfp(VMReg r) NOT_DEBUG_RETURN
                                      DEBUG_ONLY({ Unimplemented(); })
@@ -46,12 +53,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-    Unimplemented();
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     Unimplemented();
     return nullptr;
diff --git a/src/hotspot/cpu/s390/stubGenerator_s390.cpp b/src/hotspot/cpu/s390/stubGenerator_s390.cpp
index dfd20730b84..556c0d4703d 100644
--- a/src/hotspot/cpu/s390/stubGenerator_s390.cpp
+++ b/src/hotspot/cpu/s390/stubGenerator_s390.cpp
@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2016, 2023 SAP SE. All rights reserved.
+ * Copyright (c) 2016, 2024 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -705,6 +705,50 @@ class StubGenerator: public StubCodeGenerator {
     return start;
   }
 
+  address generate_lookup_secondary_supers_table_stub(u1 super_klass_index) {
+    StubCodeMark mark(this, "StubRoutines", "lookup_secondary_supers_table");
+
+    const Register
+        r_super_klass  = Z_ARG1,
+        r_sub_klass    = Z_ARG2,
+        r_array_index  = Z_ARG3,
+        r_array_length = Z_ARG4,
+        r_array_base   = Z_ARG5,
+        r_bitmap       = Z_R10,
+        r_result       = Z_R11;
+    address start = __ pc();
+
+    __ lookup_secondary_supers_table(r_sub_klass, r_super_klass,
+                                     r_array_base, r_array_length, r_array_index,
+                                     r_bitmap, r_result, super_klass_index);
+
+    __ z_br(Z_R14);
+
+    return start;
+  }
+
+  // Slow path implementation for UseSecondarySupersTable.
+  address generate_lookup_secondary_supers_table_slow_path_stub() {
+    StubCodeMark mark(this, "StubRoutines", "lookup_secondary_supers_table_slow_path");
+
+    address start = __ pc();
+
+    const Register
+        r_super_klass  = Z_ARG1,
+        r_array_base   = Z_ARG5,
+        r_temp1        = Z_ARG4,
+        r_array_index  = Z_ARG3,
+        r_bitmap       = Z_R10,
+        r_result       = Z_R11;
+
+    __ lookup_secondary_supers_table_slow_path(r_super_klass, r_array_base,
+                                               r_array_index, r_bitmap, r_result, r_temp1);
+
+    __ z_br(Z_R14);
+
+    return start;
+  }
+
 #if !defined(PRODUCT)
   // Wrapper which calls oopDesc::is_oop_or_null()
   // Only called by MacroAssembler::verify_oop
@@ -3247,6 +3291,14 @@ class StubGenerator: public StubCodeGenerator {
       StubRoutines::_montgomerySquare
         = CAST_FROM_FN_PTR(address, SharedRuntime::montgomery_square);
     }
+    if (UseSecondarySupersTable) {
+      StubRoutines::_lookup_secondary_supers_table_slow_path_stub = generate_lookup_secondary_supers_table_slow_path_stub();
+      if (!InlineSecondarySupersTest) {
+        for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
+          StubRoutines::_lookup_secondary_supers_table_stubs[slot] = generate_lookup_secondary_supers_table_stub(slot);
+        }
+      }
+    }
 #endif
 #endif // COMPILER2_OR_JVMCI
   }
diff --git a/src/hotspot/cpu/s390/vm_version_s390.cpp b/src/hotspot/cpu/s390/vm_version_s390.cpp
index af0903884fb..4b17ff4594c 100644
--- a/src/hotspot/cpu/s390/vm_version_s390.cpp
+++ b/src/hotspot/cpu/s390/vm_version_s390.cpp
@@ -1,6 +1,6 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2016, 2023 SAP SE. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -272,6 +272,13 @@ void VM_Version::initialize() {
     FLAG_SET_DEFAULT(UseSHA, false);
   }
 
+  if (UseSecondarySupersTable && VM_Version::get_model_index() < 5 /* z196/z11 */) {
+    if (!FLAG_IS_DEFAULT(UseSecondarySupersTable)) {
+      warning("UseSecondarySupersTable requires z196 or later.");
+    }
+    FLAG_SET_DEFAULT(UseSecondarySupersTable, false);
+  }
+
 #ifdef COMPILER2
   if (FLAG_IS_DEFAULT(UseMultiplyToLenIntrinsic)) {
     FLAG_SET_DEFAULT(UseMultiplyToLenIntrinsic, true);
diff --git a/src/hotspot/cpu/s390/vm_version_s390.hpp b/src/hotspot/cpu/s390/vm_version_s390.hpp
index 4f963c4e485..31fdedc59f6 100644
--- a/src/hotspot/cpu/s390/vm_version_s390.hpp
+++ b/src/hotspot/cpu/s390/vm_version_s390.hpp
@@ -413,6 +413,8 @@ class VM_Version: public Abstract_VM_Version {
   // s390 supports fast class initialization checks
   static bool supports_fast_class_init_checks() { return true; }
 
+  constexpr static bool supports_secondary_supers_table() { return true; }
+
   constexpr static bool supports_recursive_lightweight_locking() { return true; }
 
   // CPU feature query functions
diff --git a/src/hotspot/cpu/x86/gc/shenandoah/c1/shenandoahBarrierSetC1_x86.cpp b/src/hotspot/cpu/x86/gc/shenandoah/c1/shenandoahBarrierSetC1_x86.cpp
index 9995a87f5cf..032b33f40e0 100644
--- a/src/hotspot/cpu/x86/gc/shenandoah/c1/shenandoahBarrierSetC1_x86.cpp
+++ b/src/hotspot/cpu/x86/gc/shenandoah/c1/shenandoahBarrierSetC1_x86.cpp
@@ -46,9 +46,6 @@ void LIR_OpShenandoahCompareAndSwap::emit_code(LIR_Assembler* masm) {
   assert(cmpval != addr, "cmp and addr must be in different registers");
   assert(newval != addr, "new value and addr must be in different registers");
 
-  // Apply IU barrier to newval.
-  ShenandoahBarrierSet::assembler()->iu_barrier(masm->masm(), newval, tmp1);
-
 #ifdef _LP64
   if (UseCompressedOops) {
     __ encode_heap_oop(cmpval);
@@ -101,10 +98,6 @@ LIR_Opr ShenandoahBarrierSetC1::atomic_xchg_at_resolved(LIRAccess& access, LIRIt
   value.load_item();
   LIR_Opr value_opr = value.result();
 
-  if (access.is_oop()) {
-    value_opr = iu_barrier(access.gen(), value_opr, access.access_emit_info(), access.decorators());
-  }
-
   // Because we want a 2-arg form of xchg and xadd
   __ move(value_opr, result);
 
diff --git a/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp b/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp
index 25a2b931468..47078dff907 100644
--- a/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp
+++ b/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp
@@ -121,7 +121,7 @@ void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, Dec
 
   if (is_reference_type(type)) {
 
-    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahIUBarrier || ShenandoahLoadRefBarrier) {
+    if ((ShenandoahSATBBarrier && !dest_uninitialized) || ShenandoahLoadRefBarrier) {
 #ifdef _LP64
       Register thread = r15_thread;
 #else
@@ -472,40 +472,6 @@ void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm,
 #endif
 }
 
-void ShenandoahBarrierSetAssembler::iu_barrier(MacroAssembler* masm, Register dst, Register tmp) {
-  if (ShenandoahIUBarrier) {
-    iu_barrier_impl(masm, dst, tmp);
-  }
-}
-
-void ShenandoahBarrierSetAssembler::iu_barrier_impl(MacroAssembler* masm, Register dst, Register tmp) {
-  assert(ShenandoahIUBarrier, "should be enabled");
-
-  if (dst == noreg) return;
-
-  if (ShenandoahIUBarrier) {
-    save_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
-
-#ifdef _LP64
-    Register thread = r15_thread;
-#else
-    Register thread = rcx;
-    if (thread == dst || thread == tmp) {
-      thread = rdi;
-    }
-    if (thread == dst || thread == tmp) {
-      thread = rbx;
-    }
-    __ get_thread(thread);
-#endif
-    assert_different_registers(dst, tmp, thread);
-
-    satb_write_barrier_pre(masm, noreg, dst, thread, tmp, true, false);
-
-    restore_machine_state(masm, /* handle_gpr = */ true, /* handle_fp = */ true);
-  }
-}
-
 //
 // Arguments:
 //
@@ -626,12 +592,7 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet
                                    val != noreg /* tosca_live */,
                                    false /* expand_call */);
     }
-    if (val == noreg) {
-      BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
-    } else {
-      iu_barrier(masm, val, tmp3);
-      BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
-    }
+    BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
     NOT_LP64(imasm->restore_bcp());
   } else {
     BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2, tmp3);
diff --git a/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.hpp b/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.hpp
index 47dfe144928..c8140f4a76a 100644
--- a/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.hpp
+++ b/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.hpp
@@ -56,10 +56,7 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
                                     bool tosca_live,
                                     bool expand_call);
 
-  void iu_barrier_impl(MacroAssembler* masm, Register dst, Register tmp);
-
 public:
-  void iu_barrier(MacroAssembler* masm, Register dst, Register tmp);
 #ifdef COMPILER1
   void gen_pre_barrier_stub(LIR_Assembler* ce, ShenandoahPreBarrierStub* stub);
   void gen_load_reference_barrier_stub(LIR_Assembler* ce, ShenandoahLoadReferenceBarrierStub* stub);
diff --git a/src/hotspot/cpu/x86/smallRegisterMap_x86.inline.hpp b/src/hotspot/cpu/x86/smallRegisterMap_x86.inline.hpp
index 5f21939a3aa..63212a686af 100644
--- a/src/hotspot/cpu/x86/smallRegisterMap_x86.inline.hpp
+++ b/src/hotspot/cpu/x86/smallRegisterMap_x86.inline.hpp
@@ -30,8 +30,16 @@
 
 // Java frames don't have callee saved registers (except for rbp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
+
 private:
   static void assert_is_rbp(VMReg r) NOT_DEBUG_RETURN
                                      DEBUG_ONLY({ assert(r == rbp->as_VMReg() || r == rbp->as_VMReg()->next(), "Reg: %s", r->name()); })
@@ -48,17 +56,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-  #ifdef ASSERT
-    for(int i = 0; i < RegisterMap::reg_count; i++) {
-      VMReg r = VMRegImpl::as_VMReg(i);
-      if (map->location(r, (intptr_t*)nullptr) != nullptr) assert_is_rbp(r);
-    }
-  #endif
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     assert_is_rbp(reg);
     return (address)(sp - frame::sender_sp_offset);
diff --git a/src/hotspot/cpu/zero/smallRegisterMap_zero.inline.hpp b/src/hotspot/cpu/zero/smallRegisterMap_zero.inline.hpp
index b85ead32fd2..51fb114f595 100644
--- a/src/hotspot/cpu/zero/smallRegisterMap_zero.inline.hpp
+++ b/src/hotspot/cpu/zero/smallRegisterMap_zero.inline.hpp
@@ -30,8 +30,15 @@
 
 // Java frames don't have callee saved registers (except for rfp), so we can use a smaller RegisterMap
 class SmallRegisterMap {
+  constexpr SmallRegisterMap() = default;
+  ~SmallRegisterMap() = default;
+  NONCOPYABLE(SmallRegisterMap);
+
 public:
-  static constexpr SmallRegisterMap* instance = nullptr;
+  static const SmallRegisterMap* instance() {
+    static constexpr SmallRegisterMap the_instance{};
+    return &the_instance;
+  }
 private:
   static void assert_is_rfp(VMReg r) NOT_DEBUG_RETURN
                                      DEBUG_ONLY({ Unimplemented(); })
@@ -46,12 +53,6 @@ class SmallRegisterMap {
     return map;
   }
 
-  SmallRegisterMap() {}
-
-  SmallRegisterMap(const RegisterMap* map) {
-    Unimplemented();
-  }
-
   inline address location(VMReg reg, intptr_t* sp) const {
     Unimplemented();
     return nullptr;
diff --git a/src/hotspot/share/c1/c1_LIRGenerator.cpp b/src/hotspot/share/c1/c1_LIRGenerator.cpp
index cd084135658..7b519804bfe 100644
--- a/src/hotspot/share/c1/c1_LIRGenerator.cpp
+++ b/src/hotspot/share/c1/c1_LIRGenerator.cpp
@@ -1300,7 +1300,7 @@ void LIRGenerator::do_isPrimitive(Intrinsic* x) {
   }
 
   __ move(new LIR_Address(rcvr.result(), java_lang_Class::klass_offset(), T_ADDRESS), temp, info);
-  __ cmp(lir_cond_notEqual, temp, LIR_OprFact::metadataConst(0));
+  __ cmp(lir_cond_notEqual, temp, LIR_OprFact::metadataConst(nullptr));
   __ cmove(lir_cond_notEqual, LIR_OprFact::intConst(0), LIR_OprFact::intConst(1), result, T_BOOLEAN);
 }
 
@@ -1333,7 +1333,7 @@ void LIRGenerator::do_getModifiers(Intrinsic* x) {
 
   // Check if this is a Java mirror of primitive type, and select the appropriate klass.
   LIR_Opr klass = new_register(T_METADATA);
-  __ cmp(lir_cond_equal, recv_klass, LIR_OprFact::metadataConst(0));
+  __ cmp(lir_cond_equal, recv_klass, LIR_OprFact::metadataConst(nullptr));
   __ cmove(lir_cond_equal, prim_klass, recv_klass, klass, T_ADDRESS);
 
   // Get the answer.
diff --git a/src/hotspot/share/ci/ciConstantPoolCache.cpp b/src/hotspot/share/ci/ciConstantPoolCache.cpp
index 8dc9cfc75e1..e831516b0f7 100644
--- a/src/hotspot/share/ci/ciConstantPoolCache.cpp
+++ b/src/hotspot/share/ci/ciConstantPoolCache.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,7 +37,7 @@
 ciConstantPoolCache::ciConstantPoolCache(Arena* arena,
                                  int expected_size) {
   _elements =
-    new (arena) GrowableArray<void*>(arena, expected_size, 0, 0);
+    new (arena) GrowableArray<void*>(arena, expected_size, 0, nullptr);
   _keys = new (arena) GrowableArray<int>(arena, expected_size, 0, 0);
 }
 
diff --git a/src/hotspot/share/ci/ciReplay.cpp b/src/hotspot/share/ci/ciReplay.cpp
index 3ed71806b07..fd29e0cf857 100644
--- a/src/hotspot/share/ci/ciReplay.cpp
+++ b/src/hotspot/share/ci/ciReplay.cpp
@@ -132,6 +132,7 @@ class CompileReplay : public StackObj {
   char* _bufptr;
   char* _buffer;
   int   _buffer_length;
+  ReallocMark _nesting; // Safety checks for arena reallocation
 
   // "compile" data
   ciKlass* _iklass;
@@ -601,6 +602,7 @@ class CompileReplay : public StackObj {
     int buffer_pos = 0;
     while(c != EOF) {
       if (buffer_pos + 1 >= _buffer_length) {
+        _nesting.check(); // Check if a reallocation in the resource arena is safe
         int new_length = _buffer_length * 2;
         // Next call will throw error in case of OOM.
         _buffer = REALLOC_RESOURCE_ARRAY(char, _buffer, _buffer_length, new_length);
diff --git a/src/hotspot/share/ci/ciStreams.cpp b/src/hotspot/share/ci/ciStreams.cpp
index 8220910d74c..18d2a46a686 100644
--- a/src/hotspot/share/ci/ciStreams.cpp
+++ b/src/hotspot/share/ci/ciStreams.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -135,7 +135,7 @@ Bytecodes::Code ciBytecodeStream::next_wide_or_table(Bytecodes::Code bc) {
 // ------------------------------------------------------------------
 // ciBytecodeStream::reset_to_bci
 void ciBytecodeStream::reset_to_bci( int bci ) {
-  _bc_start=_was_wide=0;
+  _bc_start = _was_wide = nullptr;
   _pc = _start+bci;
 }
 
diff --git a/src/hotspot/share/classfile/classFileParser.cpp b/src/hotspot/share/classfile/classFileParser.cpp
index 535b67887fc..ddde58e5d20 100644
--- a/src/hotspot/share/classfile/classFileParser.cpp
+++ b/src/hotspot/share/classfile/classFileParser.cpp
@@ -1227,12 +1227,8 @@ void ClassFileParser::parse_field_attributes(const ClassFileStream* const cfs,
   bool is_synthetic = false;
   const u1* runtime_visible_annotations = nullptr;
   int runtime_visible_annotations_length = 0;
-  const u1* runtime_invisible_annotations = nullptr;
-  int runtime_invisible_annotations_length = 0;
   const u1* runtime_visible_type_annotations = nullptr;
   int runtime_visible_type_annotations_length = 0;
-  const u1* runtime_invisible_type_annotations = nullptr;
-  int runtime_invisible_type_annotations_length = 0;
   bool runtime_invisible_annotations_exists = false;
   bool runtime_invisible_type_annotations_exists = false;
   const ConstantPool* const cp = _cp;
@@ -1315,11 +1311,6 @@ void ClassFileParser::parse_field_attributes(const ClassFileStream* const cfs,
           return;
         }
         runtime_invisible_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_annotations_length = attribute_length;
-          runtime_invisible_annotations = cfs->current();
-          assert(runtime_invisible_annotations != nullptr, "null invisible annotations");
-        }
         cfs->skip_u1(attribute_length, CHECK);
       } else if (attribute_name == vmSymbols::tag_runtime_visible_type_annotations()) {
         if (runtime_visible_type_annotations != nullptr) {
@@ -1339,11 +1330,6 @@ void ClassFileParser::parse_field_attributes(const ClassFileStream* const cfs,
         } else {
           runtime_invisible_type_annotations_exists = true;
         }
-        if (PreserveAllAnnotations) {
-          runtime_invisible_type_annotations_length = attribute_length;
-          runtime_invisible_type_annotations = cfs->current();
-          assert(runtime_invisible_type_annotations != nullptr, "null invisible type annotations");
-        }
         cfs->skip_u1(attribute_length, CHECK);
       } else {
         cfs->skip_u1(attribute_length, CHECK);  // Skip unknown attributes
@@ -1356,16 +1342,12 @@ void ClassFileParser::parse_field_attributes(const ClassFileStream* const cfs,
   *constantvalue_index_addr = constantvalue_index;
   *is_synthetic_addr = is_synthetic;
   *generic_signature_index_addr = generic_signature_index;
-  AnnotationArray* a = assemble_annotations(runtime_visible_annotations,
+  AnnotationArray* a = allocate_annotations(runtime_visible_annotations,
                                             runtime_visible_annotations_length,
-                                            runtime_invisible_annotations,
-                                            runtime_invisible_annotations_length,
                                             CHECK);
   parsed_annotations->set_field_annotations(a);
-  a = assemble_annotations(runtime_visible_type_annotations,
+  a = allocate_annotations(runtime_visible_type_annotations,
                            runtime_visible_type_annotations_length,
-                           runtime_invisible_type_annotations,
-                           runtime_invisible_type_annotations_length,
                            CHECK);
   parsed_annotations->set_field_type_annotations(a);
   return;
@@ -2164,57 +2146,40 @@ void ClassFileParser::copy_localvariable_table(const ConstMethod* cm,
 void ClassFileParser::copy_method_annotations(ConstMethod* cm,
                                        const u1* runtime_visible_annotations,
                                        int runtime_visible_annotations_length,
-                                       const u1* runtime_invisible_annotations,
-                                       int runtime_invisible_annotations_length,
                                        const u1* runtime_visible_parameter_annotations,
                                        int runtime_visible_parameter_annotations_length,
-                                       const u1* runtime_invisible_parameter_annotations,
-                                       int runtime_invisible_parameter_annotations_length,
                                        const u1* runtime_visible_type_annotations,
                                        int runtime_visible_type_annotations_length,
-                                       const u1* runtime_invisible_type_annotations,
-                                       int runtime_invisible_type_annotations_length,
                                        const u1* annotation_default,
                                        int annotation_default_length,
                                        TRAPS) {
 
   AnnotationArray* a;
 
-  if (runtime_visible_annotations_length +
-      runtime_invisible_annotations_length > 0) {
-     a = assemble_annotations(runtime_visible_annotations,
+  if (runtime_visible_annotations_length > 0) {
+     a = allocate_annotations(runtime_visible_annotations,
                               runtime_visible_annotations_length,
-                              runtime_invisible_annotations,
-                              runtime_invisible_annotations_length,
                               CHECK);
      cm->set_method_annotations(a);
   }
 
-  if (runtime_visible_parameter_annotations_length +
-      runtime_invisible_parameter_annotations_length > 0) {
-    a = assemble_annotations(runtime_visible_parameter_annotations,
+  if (runtime_visible_parameter_annotations_length > 0) {
+    a = allocate_annotations(runtime_visible_parameter_annotations,
                              runtime_visible_parameter_annotations_length,
-                             runtime_invisible_parameter_annotations,
-                             runtime_invisible_parameter_annotations_length,
                              CHECK);
     cm->set_parameter_annotations(a);
   }
 
   if (annotation_default_length > 0) {
-    a = assemble_annotations(annotation_default,
+    a = allocate_annotations(annotation_default,
                              annotation_default_length,
-                             nullptr,
-                             0,
                              CHECK);
     cm->set_default_annotations(a);
   }
 
-  if (runtime_visible_type_annotations_length +
-      runtime_invisible_type_annotations_length > 0) {
-    a = assemble_annotations(runtime_visible_type_annotations,
+  if (runtime_visible_type_annotations_length > 0) {
+    a = allocate_annotations(runtime_visible_type_annotations,
                              runtime_visible_type_annotations_length,
-                             runtime_invisible_type_annotations,
-                             runtime_invisible_type_annotations_length,
                              CHECK);
     cm->set_type_annotations(a);
   }
@@ -2296,7 +2261,7 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
   u2 max_stack = 0;
   u2 max_locals = 0;
   u4 code_length = 0;
-  const u1* code_start = 0;
+  const u1* code_start = nullptr;
   u2 exception_table_length = 0;
   const unsafe_u2* exception_table_start = nullptr; // (potentially unaligned) pointer to array of u2 elements
   Array<int>* exception_handlers = Universe::the_empty_int_array();
@@ -2327,16 +2292,10 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
   MethodAnnotationCollector parsed_annotations;
   const u1* runtime_visible_annotations = nullptr;
   int runtime_visible_annotations_length = 0;
-  const u1* runtime_invisible_annotations = nullptr;
-  int runtime_invisible_annotations_length = 0;
   const u1* runtime_visible_parameter_annotations = nullptr;
   int runtime_visible_parameter_annotations_length = 0;
-  const u1* runtime_invisible_parameter_annotations = nullptr;
-  int runtime_invisible_parameter_annotations_length = 0;
   const u1* runtime_visible_type_annotations = nullptr;
   int runtime_visible_type_annotations_length = 0;
-  const u1* runtime_invisible_type_annotations = nullptr;
-  int runtime_invisible_type_annotations_length = 0;
   bool runtime_invisible_annotations_exists = false;
   bool runtime_invisible_type_annotations_exists = false;
   bool runtime_invisible_parameter_annotations_exists = false;
@@ -2607,11 +2566,6 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
           return nullptr;
         }
         runtime_invisible_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_annotations_length = method_attribute_length;
-          runtime_invisible_annotations = cfs->current();
-          assert(runtime_invisible_annotations != nullptr, "null invisible annotations");
-        }
         cfs->skip_u1(method_attribute_length, CHECK_NULL);
       } else if (method_attribute_name == vmSymbols::tag_runtime_visible_parameter_annotations()) {
         if (runtime_visible_parameter_annotations != nullptr) {
@@ -2632,12 +2586,6 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
           return nullptr;
         }
         runtime_invisible_parameter_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_parameter_annotations_length = method_attribute_length;
-          runtime_invisible_parameter_annotations = cfs->current();
-          assert(runtime_invisible_parameter_annotations != nullptr,
-            "null invisible parameter annotations");
-        }
         cfs->skip_u1(method_attribute_length, CHECK_NULL);
       } else if (method_attribute_name == vmSymbols::tag_annotation_default()) {
         if (annotation_default != nullptr) {
@@ -2668,14 +2616,8 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
             "Multiple RuntimeInvisibleTypeAnnotations attributes for method in class file %s",
             THREAD);
           return nullptr;
-        } else {
-          runtime_invisible_type_annotations_exists = true;
-        }
-        if (PreserveAllAnnotations) {
-          runtime_invisible_type_annotations_length = method_attribute_length;
-          runtime_invisible_type_annotations = cfs->current();
-          assert(runtime_invisible_type_annotations != nullptr, "null invisible type annotations");
         }
+        runtime_invisible_type_annotations_exists = true;
         cfs->skip_u1(method_attribute_length, CHECK_NULL);
       } else {
         // Skip unknown attributes
@@ -2709,12 +2651,9 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
       checked_exceptions_length,
       method_parameters_length,
       generic_signature_index,
-      runtime_visible_annotations_length +
-           runtime_invisible_annotations_length,
-      runtime_visible_parameter_annotations_length +
-           runtime_invisible_parameter_annotations_length,
-      runtime_visible_type_annotations_length +
-           runtime_invisible_type_annotations_length,
+      runtime_visible_annotations_length,
+      runtime_visible_parameter_annotations_length,
+      runtime_visible_type_annotations_length,
       annotation_default_length,
       0);
 
@@ -2806,16 +2745,10 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
   copy_method_annotations(m->constMethod(),
                           runtime_visible_annotations,
                           runtime_visible_annotations_length,
-                          runtime_invisible_annotations,
-                          runtime_invisible_annotations_length,
                           runtime_visible_parameter_annotations,
                           runtime_visible_parameter_annotations_length,
-                          runtime_invisible_parameter_annotations,
-                          runtime_invisible_parameter_annotations_length,
                           runtime_visible_type_annotations,
                           runtime_visible_type_annotations_length,
-                          runtime_invisible_type_annotations,
-                          runtime_invisible_type_annotations_length,
                           annotation_default,
                           annotation_default_length,
                           CHECK_NULL);
@@ -3295,13 +3228,9 @@ u4 ClassFileParser::parse_classfile_record_attribute(const ClassFileStream* cons
     u2 generic_sig_index = 0;
     const u1* runtime_visible_annotations = nullptr;
     int runtime_visible_annotations_length = 0;
-    const u1* runtime_invisible_annotations = nullptr;
-    int runtime_invisible_annotations_length = 0;
     bool runtime_invisible_annotations_exists = false;
     const u1* runtime_visible_type_annotations = nullptr;
     int runtime_visible_type_annotations_length = 0;
-    const u1* runtime_invisible_type_annotations = nullptr;
-    int runtime_invisible_type_annotations_length = 0;
     bool runtime_invisible_type_annotations_exists = false;
 
     // Expected attributes for record components are Signature, Runtime(In)VisibleAnnotations,
@@ -3352,11 +3281,6 @@ u4 ClassFileParser::parse_classfile_record_attribute(const ClassFileStream* cons
           return 0;
         }
         runtime_invisible_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_annotations_length = attribute_length;
-          runtime_invisible_annotations = cfs->current();
-          assert(runtime_invisible_annotations != nullptr, "null record component invisible annotation");
-        }
         cfs->skip_u1(attribute_length, CHECK_0);
 
       } else if (attribute_name == vmSymbols::tag_runtime_visible_type_annotations()) {
@@ -3379,11 +3303,6 @@ u4 ClassFileParser::parse_classfile_record_attribute(const ClassFileStream* cons
           return 0;
         }
         runtime_invisible_type_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_type_annotations_length = attribute_length;
-          runtime_invisible_type_annotations = cfs->current();
-          assert(runtime_invisible_type_annotations != nullptr, "null record component invisible type annotation");
-        }
         cfs->skip_u1(attribute_length, CHECK_0);
 
       } else {
@@ -3393,15 +3312,11 @@ u4 ClassFileParser::parse_classfile_record_attribute(const ClassFileStream* cons
       calculate_attr_size += attribute_length;
     } // End of attributes For loop
 
-    AnnotationArray* annotations = assemble_annotations(runtime_visible_annotations,
+    AnnotationArray* annotations = allocate_annotations(runtime_visible_annotations,
                                                         runtime_visible_annotations_length,
-                                                        runtime_invisible_annotations,
-                                                        runtime_invisible_annotations_length,
                                                         CHECK_0);
-    AnnotationArray* type_annotations = assemble_annotations(runtime_visible_type_annotations,
+    AnnotationArray* type_annotations = allocate_annotations(runtime_visible_type_annotations,
                                                              runtime_visible_type_annotations_length,
-                                                             runtime_invisible_type_annotations,
-                                                             runtime_invisible_type_annotations_length,
                                                              CHECK_0);
 
     RecordComponent* record_component =
@@ -3538,12 +3453,8 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
   bool parsed_bootstrap_methods_attribute = false;
   const u1* runtime_visible_annotations = nullptr;
   int runtime_visible_annotations_length = 0;
-  const u1* runtime_invisible_annotations = nullptr;
-  int runtime_invisible_annotations_length = 0;
   const u1* runtime_visible_type_annotations = nullptr;
   int runtime_visible_type_annotations_length = 0;
-  const u1* runtime_invisible_type_annotations = nullptr;
-  int runtime_invisible_type_annotations_length = 0;
   bool runtime_invisible_type_annotations_exists = false;
   bool runtime_invisible_annotations_exists = false;
   bool parsed_source_debug_ext_annotations_exist = false;
@@ -3656,11 +3567,6 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
           return;
         }
         runtime_invisible_annotations_exists = true;
-        if (PreserveAllAnnotations) {
-          runtime_invisible_annotations_length = attribute_length;
-          runtime_invisible_annotations = cfs->current();
-          assert(runtime_invisible_annotations != nullptr, "null invisible annotations");
-        }
         cfs->skip_u1(attribute_length, CHECK);
       } else if (tag == vmSymbols::tag_enclosing_method()) {
         if (parsed_enclosingmethod_attribute) {
@@ -3712,14 +3618,8 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
           classfile_parse_error(
             "Multiple RuntimeInvisibleTypeAnnotations attributes in class file %s", THREAD);
           return;
-        } else {
-          runtime_invisible_type_annotations_exists = true;
-        }
-        if (PreserveAllAnnotations) {
-          runtime_invisible_type_annotations_length = attribute_length;
-          runtime_invisible_type_annotations = cfs->current();
-          assert(runtime_invisible_type_annotations != nullptr, "null invisible type annotations");
         }
+        runtime_invisible_type_annotations_exists = true;
         cfs->skip_u1(attribute_length, CHECK);
       } else if (_major_version >= JAVA_11_VERSION) {
         if (tag == vmSymbols::tag_nest_members()) {
@@ -3799,15 +3699,11 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
       cfs->skip_u1(attribute_length, CHECK);
     }
   }
-  _class_annotations = assemble_annotations(runtime_visible_annotations,
+  _class_annotations = allocate_annotations(runtime_visible_annotations,
                                             runtime_visible_annotations_length,
-                                            runtime_invisible_annotations,
-                                            runtime_invisible_annotations_length,
                                             CHECK);
-  _class_type_annotations = assemble_annotations(runtime_visible_type_annotations,
+  _class_type_annotations = allocate_annotations(runtime_visible_type_annotations,
                                                  runtime_visible_type_annotations_length,
-                                                 runtime_invisible_type_annotations,
-                                                 runtime_invisible_type_annotations_length,
                                                  CHECK);
 
   if (parsed_innerclasses_attribute || parsed_enclosingmethod_attribute) {
@@ -3943,28 +3839,16 @@ void ClassFileParser::apply_parsed_class_metadata(
   clear_class_metadata();
 }
 
-AnnotationArray* ClassFileParser::assemble_annotations(const u1* const runtime_visible_annotations,
-                                                       int runtime_visible_annotations_length,
-                                                       const u1* const runtime_invisible_annotations,
-                                                       int runtime_invisible_annotations_length,
+AnnotationArray* ClassFileParser::allocate_annotations(const u1* const anno,
+                                                       int anno_length,
                                                        TRAPS) {
   AnnotationArray* annotations = nullptr;
-  if (runtime_visible_annotations != nullptr ||
-      runtime_invisible_annotations != nullptr) {
+  if (anno != nullptr) {
     annotations = MetadataFactory::new_array<u1>(_loader_data,
-                                          runtime_visible_annotations_length +
-                                          runtime_invisible_annotations_length,
-                                          CHECK_(annotations));
-    if (runtime_visible_annotations != nullptr) {
-      for (int i = 0; i < runtime_visible_annotations_length; i++) {
-        annotations->at_put(i, runtime_visible_annotations[i]);
-      }
-    }
-    if (runtime_invisible_annotations != nullptr) {
-      for (int i = 0; i < runtime_invisible_annotations_length; i++) {
-        int append = runtime_visible_annotations_length+i;
-        annotations->at_put(append, runtime_invisible_annotations[i]);
-      }
+                                                 anno_length,
+                                                 CHECK_(annotations));
+    for (int i = 0; i < anno_length; i++) {
+      annotations->at_put(i, anno[i]);
     }
   }
   return annotations;
diff --git a/src/hotspot/share/classfile/classFileParser.hpp b/src/hotspot/share/classfile/classFileParser.hpp
index f43303722a8..69d1f357ca5 100644
--- a/src/hotspot/share/classfile/classFileParser.hpp
+++ b/src/hotspot/share/classfile/classFileParser.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -347,10 +347,8 @@ class ClassFileParser {
                                                    TRAPS);
 
   // Annotations handling
-  AnnotationArray* assemble_annotations(const u1* const runtime_visible_annotations,
-                                        int runtime_visible_annotations_length,
-                                        const u1* const runtime_invisible_annotations,
-                                        int runtime_invisible_annotations_length,
+  AnnotationArray* allocate_annotations(const u1* const anno,
+                                        int anno_length,
                                         TRAPS);
 
   void set_precomputed_flags(InstanceKlass* k);
@@ -514,16 +512,10 @@ class ClassFileParser {
   void copy_method_annotations(ConstMethod* cm,
                                const u1* runtime_visible_annotations,
                                int runtime_visible_annotations_length,
-                               const u1* runtime_invisible_annotations,
-                               int runtime_invisible_annotations_length,
                                const u1* runtime_visible_parameter_annotations,
                                int runtime_visible_parameter_annotations_length,
-                               const u1* runtime_invisible_parameter_annotations,
-                               int runtime_invisible_parameter_annotations_length,
                                const u1* runtime_visible_type_annotations,
                                int runtime_visible_type_annotations_length,
-                               const u1* runtime_invisible_type_annotations,
-                               int runtime_invisible_type_annotations_length,
                                const u1* annotation_default,
                                int annotation_default_length,
                                TRAPS);
diff --git a/src/hotspot/share/classfile/defaultMethods.cpp b/src/hotspot/share/classfile/defaultMethods.cpp
index dd221efb409..58d24c16ad3 100644
--- a/src/hotspot/share/classfile/defaultMethods.cpp
+++ b/src/hotspot/share/classfile/defaultMethods.cpp
@@ -870,7 +870,7 @@ static Method* new_method(
     Symbol* sig, AccessFlags flags, int max_stack, int params,
     ConstMethod::MethodType mt, TRAPS) {
 
-  address code_start = 0;
+  address code_start = nullptr;
   int code_length = 0;
   InlineTableSizes sizes;
 
diff --git a/src/hotspot/share/classfile/javaAssertions.cpp b/src/hotspot/share/classfile/javaAssertions.cpp
index 2666683046b..cf51bfb21d6 100644
--- a/src/hotspot/share/classfile/javaAssertions.cpp
+++ b/src/hotspot/share/classfile/javaAssertions.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,12 +38,12 @@
 
 bool                            JavaAssertions::_userDefault = false;
 bool                            JavaAssertions::_sysDefault = false;
-JavaAssertions::OptionList*     JavaAssertions::_classes = 0;
-JavaAssertions::OptionList*     JavaAssertions::_packages = 0;
+JavaAssertions::OptionList*     JavaAssertions::_classes = nullptr;
+JavaAssertions::OptionList*     JavaAssertions::_packages = nullptr;
 
 JavaAssertions::OptionList::OptionList(const char* name, bool enabled,
   OptionList* next) {
-  assert(name != 0, "need a name");
+  assert(name != nullptr, "need a name");
   _name = name;
   _enabled = enabled;
   _next = next;
@@ -51,12 +51,12 @@ JavaAssertions::OptionList::OptionList(const char* name, bool enabled,
 
 int JavaAssertions::OptionList::count(OptionList* p) {
   int rc;
-  for (rc = 0; p != 0; p = p->next(), ++rc) /* empty */;
+  for (rc = 0; p != nullptr; p = p->next(), ++rc) /* empty */;
   return rc;
 }
 
 void JavaAssertions::addOption(const char* name, bool enable) {
-  assert(name != 0, "must have a name");
+  assert(name != nullptr, "must have a name");
 
   // Copy the name.  The storage needs to exist for the lifetime of the vm;
   // it is never freed, so will be leaked (along with other option strings -
@@ -135,7 +135,7 @@ void JavaAssertions::fillJavaArrays(const OptionList* p, int len,
   // matches the order on the command line (the list is in reverse order, since
   // it was created by prepending successive items from the command line).
   int index;
-  for (index = len - 1; p != 0; p = p->next(), --index) {
+  for (index = len - 1; p != nullptr; p = p->next(), --index) {
     assert(index >= 0, "length does not match list");
     TempNewSymbol name = SymbolTable::new_symbol(p->name());
     Handle s = java_lang_String::externalize_classname(name, CHECK);
@@ -147,12 +147,12 @@ void JavaAssertions::fillJavaArrays(const OptionList* p, int len,
 
 inline JavaAssertions::OptionList*
 JavaAssertions::match_class(const char* classname) {
-  for (OptionList* p = _classes; p != 0; p = p->next()) {
+  for (OptionList* p = _classes; p != nullptr; p = p->next()) {
     if (strcmp(p->name(), classname) == 0) {
       return p;
     }
   }
-  return 0;
+  return nullptr;
 }
 
 JavaAssertions::OptionList*
@@ -160,7 +160,7 @@ JavaAssertions::match_package(const char* classname) {
   // Search the package list for any items that apply to classname.  Each
   // sub-package in classname is checked, from most-specific to least, until one
   // is found.
-  if (_packages == 0) return 0;
+  if (_packages == nullptr) return nullptr;
 
   // Find the length of the "most-specific" package in classname.  If classname
   // does not include a package, length will be 0 which will match items for the
@@ -170,7 +170,7 @@ JavaAssertions::match_package(const char* classname) {
 
   do {
     assert(len == 0 || classname[len] == JVM_SIGNATURE_SLASH, "not a package name");
-    for (OptionList* p = _packages; p != 0; p = p->next()) {
+    for (OptionList* p = _packages; p != nullptr; p = p->next()) {
       if (strncmp(p->name(), classname, len) == 0 && p->name()[len] == '\0') {
         return p;
       }
@@ -181,7 +181,7 @@ JavaAssertions::match_package(const char* classname) {
     while (len > 0 && classname[--len] != JVM_SIGNATURE_SLASH) /* empty */;
   } while (len > 0);
 
-  return 0;
+  return nullptr;
 }
 
 inline void JavaAssertions::trace(const char* name,
@@ -193,7 +193,7 @@ const char* typefound, const char* namefound, bool enabled) {
 }
 
 bool JavaAssertions::enabled(const char* classname, bool systemClass) {
-  assert(classname != 0, "must have a classname");
+  assert(classname != nullptr, "must have a classname");
 
   // This will be slow if the number of assertion options on the command line is
   // large--it traverses two lists, one of them multiple times.  Could use a
diff --git a/src/hotspot/share/classfile/symbolTable.cpp b/src/hotspot/share/classfile/symbolTable.cpp
index ddbf180a4a1..95094238946 100644
--- a/src/hotspot/share/classfile/symbolTable.cpp
+++ b/src/hotspot/share/classfile/symbolTable.cpp
@@ -193,7 +193,7 @@ class SymbolTableConfig : public AllStatic {
       // We cannot use arena because arena chunks are allocated by the OS. As a result, for example,
       // the archived symbol of "java/lang/Object" may sometimes be lower than "java/lang/String", and
       // sometimes be higher. This would cause non-deterministic contents in the archive.
-      DEBUG_ONLY(static void* last = 0);
+      DEBUG_ONLY(static void* last = nullptr);
       void* p = (void*)MetaspaceShared::symbol_space_alloc(alloc_size);
       assert(p > last, "must increase monotonically");
       DEBUG_ONLY(last = p);
diff --git a/src/hotspot/share/code/codeCache.cpp b/src/hotspot/share/code/codeCache.cpp
index 4a54fd8d0a9..a491dd62f07 100644
--- a/src/hotspot/share/code/codeCache.cpp
+++ b/src/hotspot/share/code/codeCache.cpp
@@ -165,8 +165,8 @@ class CodeBlob_sizes {
 // Iterate over all CodeBlobs (cb) on the given CodeHeap
 #define FOR_ALL_BLOBS(cb, heap) for (CodeBlob* cb = first_blob(heap); cb != nullptr; cb = next_blob(heap, cb))
 
-address CodeCache::_low_bound = 0;
-address CodeCache::_high_bound = 0;
+address CodeCache::_low_bound = nullptr;
+address CodeCache::_high_bound = nullptr;
 volatile int CodeCache::_number_of_nmethods_with_dependencies = 0;
 ExceptionCache* volatile CodeCache::_exception_cache_purge_list = nullptr;
 
@@ -1790,15 +1790,17 @@ void CodeCache::log_state(outputStream* st) {
 #ifdef LINUX
 void CodeCache::write_perf_map(const char* filename, outputStream* st) {
   MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-
-  // Perf expects to find the map file at /tmp/perf-<pid>.map
-  // if the file name is not specified.
-  char fname[32];
+  char fname[JVM_MAXPATHLEN];
   if (filename == nullptr) {
-    jio_snprintf(fname, sizeof(fname), "/tmp/perf-%d.map", os::current_process_id());
+    // Invocation outside of jcmd requires pid substitution.
+    if (!Arguments::copy_expand_pid(DEFAULT_PERFMAP_FILENAME,
+                                    strlen(DEFAULT_PERFMAP_FILENAME),
+                                    fname, JVM_MAXPATHLEN)) {
+      st->print_cr("Warning: Not writing perf map as pid substitution failed.");
+      return;
+    }
     filename = fname;
   }
-
   fileStream fs(filename, "w");
   if (!fs.is_open()) {
     st->print_cr("Warning: Failed to create %s for perf map", filename);
diff --git a/src/hotspot/share/code/codeCache.hpp b/src/hotspot/share/code/codeCache.hpp
index 565f600453e..b724268b650 100644
--- a/src/hotspot/share/code/codeCache.hpp
+++ b/src/hotspot/share/code/codeCache.hpp
@@ -80,6 +80,10 @@ class ShenandoahParallelCodeHeapIterator;
 class NativePostCallNop;
 class DeoptimizationScope;
 
+#ifdef LINUX
+#define DEFAULT_PERFMAP_FILENAME "/tmp/perf-%p.map"
+#endif
+
 class CodeCache : AllStatic {
   friend class VMStructs;
   friend class JVMCIVMStructs;
diff --git a/src/hotspot/share/code/dependencies.cpp b/src/hotspot/share/code/dependencies.cpp
index 7d3b744313f..074846e2e79 100644
--- a/src/hotspot/share/code/dependencies.cpp
+++ b/src/hotspot/share/code/dependencies.cpp
@@ -72,7 +72,7 @@ void Dependencies::initialize(ciEnv* env) {
 #endif
   DEBUG_ONLY(_deps[end_marker] = nullptr);
   for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
-    _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, 0);
+    _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, nullptr);
   }
   _content_bytes = nullptr;
   _size_in_bytes = (size_t)-1;
diff --git a/src/hotspot/share/code/nmethod.cpp b/src/hotspot/share/code/nmethod.cpp
index 54aeac6be04..0bab731ac56 100644
--- a/src/hotspot/share/code/nmethod.cpp
+++ b/src/hotspot/share/code/nmethod.cpp
@@ -3270,7 +3270,7 @@ void nmethod::print_recorded_oop(int log_n, int i) {
   if (value == Universe::non_oop_word()) {
     tty->print("non-oop word");
   } else {
-    if (value == 0) {
+    if (value == nullptr) {
       tty->print("nullptr-oop");
     } else {
       oop_at(i)->print_value_on(tty);
diff --git a/src/hotspot/share/code/oopRecorder.cpp b/src/hotspot/share/code/oopRecorder.cpp
index b8ecc1eccc0..fd13b105041 100644
--- a/src/hotspot/share/code/oopRecorder.cpp
+++ b/src/hotspot/share/code/oopRecorder.cpp
@@ -68,11 +68,11 @@ template <class T> void ValueRecorder<T>::copy_values_to(nmethod* nm) {
 template <class T> void ValueRecorder<T>::maybe_initialize() {
   if (_handles == nullptr) {
     if (_arena != nullptr) {
-      _handles  = new(_arena) GrowableArray<T>(_arena, 10, 0, 0);
-      _no_finds = new(_arena) GrowableArray<int>(    _arena, 10, 0, 0);
+      _handles  = new(_arena) GrowableArray<T>(_arena, 10, 0, T{});
+      _no_finds = new(_arena) GrowableArray<int>(_arena, 10, 0, 0);
     } else {
-      _handles  = new GrowableArray<T>(10, 0, 0);
-      _no_finds = new GrowableArray<int>(    10, 0, 0);
+      _handles  = new GrowableArray<T>(10, 0, T{});
+      _no_finds = new GrowableArray<int>(10, 0, 0);
     }
   }
 }
diff --git a/src/hotspot/share/compiler/compilationMemoryStatistic.cpp b/src/hotspot/share/compiler/compilationMemoryStatistic.cpp
index 07d8ec41598..4cc2043656e 100644
--- a/src/hotspot/share/compiler/compilationMemoryStatistic.cpp
+++ b/src/hotspot/share/compiler/compilationMemoryStatistic.cpp
@@ -51,29 +51,36 @@
 #include "utilities/quickSort.hpp"
 #include "utilities/resourceHash.hpp"
 
-ArenaStatCounter::ArenaStatCounter() :
-  _current(0), _start(0), _peak(0),
-  _na(0), _ra(0),
-  _limit(0), _hit_limit(false), _limit_in_process(false),
-  _na_at_peak(0), _ra_at_peak(0), _live_nodes_at_peak(0)
-{}
-
-size_t ArenaStatCounter::peak_since_start() const {
-  return _peak > _start ? _peak - _start : 0;
+ArenaStatCounter::ArenaStatCounter() {
+  reset();
+}
+
+void ArenaStatCounter::reset() {
+  _current = 0;
+  _peak = 0;
+  _current_by_tag.clear();
+  _peak_by_tag.clear();
+  _limit = 0;
+  _hit_limit = false;
+  _limit_in_process = false;
+  _live_nodes_at_peak = 0;
+  _active = false;
 }
 
 void ArenaStatCounter::start(size_t limit) {
-  _peak = _start = _current;
+  reset();
+  _active = true;
   _limit = limit;
-  _hit_limit = false;
 }
 
-void ArenaStatCounter::end(){
+void ArenaStatCounter::end() {
   _limit = 0;
   _hit_limit = false;
+  _active = false;
 }
 
 void ArenaStatCounter::update_c2_node_count() {
+  assert(_active, "compilaton has not yet started");
 #ifdef COMPILER2
   CompilerThread* const th = Thread::current()->as_Compiler_thread();
   const CompileTask* const task = th->task();
@@ -90,33 +97,27 @@ void ArenaStatCounter::update_c2_node_count() {
 
 // Account an arena allocation or de-allocation.
 bool ArenaStatCounter::account(ssize_t delta, int tag) {
+  assert(_active, "compilaton has not yet started");
   bool rc = false;
 #ifdef ASSERT
   // Note: if this fires, we free more arena memory under the scope of the
   // CompilationMemoryHistoryMark than we allocate. This cannot be since we
   // assume arena allocations in CompilerThread to be stack bound and symmetric.
   assert(delta >= 0 || ((ssize_t)_current + delta) >= 0,
-         "Negative overflow (d=%zd %zu %zu %zu)", delta, _current, _start, _peak);
+         "Negative overflow (d=%zd %zu %zu)", delta, _current, _peak);
 #endif
   // Update totals
   _current += delta;
-  // Update detail counter
-  switch ((Arena::Tag)tag) {
-    case Arena::Tag::tag_ra: _ra += delta; break;
-    case Arena::Tag::tag_node: _na += delta; break;
-    default: // ignore
-      break;
-  };
+  _current_by_tag.add(tag, delta);
   // Did we reach a peak?
   if (_current > _peak) {
     _peak = _current;
-    assert(delta > 0, "Sanity (%zu %zu %zu)", _current, _start, _peak);
-    _na_at_peak = _na;
-    _ra_at_peak = _ra;
+    assert(delta > 0, "Sanity (%zu %zu)", _current, _peak);
     update_c2_node_count();
+    _peak_by_tag = _current_by_tag;
     rc = true;
     // Did we hit the memory limit?
-    if (!_hit_limit && _limit > 0 && peak_since_start() > _limit) {
+    if (!_hit_limit && _limit > 0 && _peak > _limit) {
       _hit_limit = true;
     }
   }
@@ -124,9 +125,15 @@ bool ArenaStatCounter::account(ssize_t delta, int tag) {
 }
 
 void ArenaStatCounter::print_on(outputStream* st) const {
-  st->print("%zu [na %zu ra %zu]", peak_since_start(), _na_at_peak, _ra_at_peak);
+  st->print("%zu [", _peak);
+  for (int tag = 0; tag < _peak_by_tag.element_count(); tag++) {
+    if (_peak_by_tag.counter(tag) > 0) {
+      st->print("%s %zu ", _peak_by_tag.tag_name(tag), _peak_by_tag.counter(tag));
+    }
+  }
+  st->print("]");
 #ifdef ASSERT
-  st->print(" (%zu->%zu->%zu)", _start, _peak, _current);
+  st->print(" (%zu->%zu)", _peak, _current);
 #endif
 }
 
@@ -186,10 +193,8 @@ class MemStatEntry : public CHeapObj<mtInternal> {
 
   // peak usage, bytes, over all arenas
   size_t _total;
-  // usage in node arena when total peaked
-  size_t _na_at_peak;
-  // usage in resource area when total peaked
-  size_t _ra_at_peak;
+  // usage per arena tag when total peaked
+  ArenaCountersByTag _peak_by_tag;
   // number of nodes (c2 only) when total peaked
   unsigned _live_nodes_at_peak;
   const char* _result;
@@ -199,8 +204,9 @@ class MemStatEntry : public CHeapObj<mtInternal> {
   MemStatEntry(FullMethodName method)
     : _method(method), _comptype(compiler_c1),
       _time(0), _num_recomp(0), _thread(nullptr), _limit(0),
-      _total(0), _na_at_peak(0), _ra_at_peak(0), _live_nodes_at_peak(0),
+      _total(0), _live_nodes_at_peak(0),
       _result(nullptr) {
+    _peak_by_tag.clear();
   }
 
   void set_comptype(CompilerType comptype) { _comptype = comptype; }
@@ -210,8 +216,7 @@ class MemStatEntry : public CHeapObj<mtInternal> {
   void inc_recompilation() { _num_recomp++; }
 
   void set_total(size_t n) { _total = n; }
-  void set_na_at_peak(size_t n) { _na_at_peak = n; }
-  void set_ra_at_peak(size_t n) { _ra_at_peak = n; }
+  void set_peak_by_tag(ArenaCountersByTag peak_by_tag) { _peak_by_tag = peak_by_tag; }
   void set_live_nodes_at_peak(unsigned n) { _live_nodes_at_peak = n; }
 
   void set_result(const char* s) { _result = s; }
@@ -219,21 +224,34 @@ class MemStatEntry : public CHeapObj<mtInternal> {
   size_t total() const { return _total; }
 
   static void print_legend(outputStream* st) {
+#define LEGEND_KEY_FMT "%11s"
     st->print_cr("Legend:");
-    st->print_cr("  total  : memory allocated via arenas while compiling");
-    st->print_cr("  NA     : ...how much in node arenas (if c2)");
-    st->print_cr("  RA     : ...how much in resource areas");
-    st->print_cr("  result : Result: 'ok' finished successfully, 'oom' hit memory limit, 'err' compilation failed");
-    st->print_cr("  #nodes : ...how many nodes (c2 only)");
-    st->print_cr("  limit  : memory limit, if set");
-    st->print_cr("  time   : time of last compilation (sec)");
-    st->print_cr("  type   : compiler type");
-    st->print_cr("  #rc    : how often recompiled");
-    st->print_cr("  thread : compiler thread");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "total", "memory allocated via arenas while compiling");
+    for (int tag = 0; tag < Arena::tag_count(); tag++) {
+      st->print_cr("  " LEGEND_KEY_FMT ": %s", Arena::tag_name[tag], Arena::tag_desc[tag]);
+    }
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "result", "Result: 'ok' finished successfully, 'oom' hit memory limit, 'err' compilation failed");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "#nodes", "...how many nodes (c2 only)");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "limit", "memory limit, if set");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "time", "time taken for last compilation (sec)");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "type", "compiler type");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "#rc", "how often recompiled");
+    st->print_cr("  " LEGEND_KEY_FMT ": %s", "thread", "compiler thread");
+#undef LEGEND_KEY_FMT
   }
 
   static void print_header(outputStream* st) {
-    st->print_cr("total     NA        RA        result  #nodes  limit   time    type  #rc thread              method");
+#define SIZE_FMT "%-10s"
+    st->print(SIZE_FMT, "total");
+    for (int tag = 0; tag < Arena::tag_count(); tag++) {
+      st->print(SIZE_FMT, Arena::tag_name[tag]);
+    }
+#define HDR_FMT1 "%-8s%-8s%-8s%-8s"
+#define HDR_FMT2 "%-6s%-4s%-19s%s"
+
+    st->print(HDR_FMT1, "result", "#nodes", "limit", "time");
+    st->print(HDR_FMT2, "type", "#rc", "thread", "method");
+    st->print_cr("");
   }
 
   void print_on(outputStream* st, bool human_readable) const {
@@ -247,21 +265,14 @@ class MemStatEntry : public CHeapObj<mtInternal> {
     }
     col += 10; st->fill_to(col);
 
-    // NA
-    if (human_readable) {
-      st->print(PROPERFMT " ", PROPERFMTARGS(_na_at_peak));
-    } else {
-      st->print("%zu ", _na_at_peak);
-    }
-    col += 10; st->fill_to(col);
-
-    // RA
-    if (human_readable) {
-      st->print(PROPERFMT " ", PROPERFMTARGS(_ra_at_peak));
-    } else {
-      st->print("%zu ", _ra_at_peak);
+    for (int tag = 0; tag < Arena::tag_count(); tag++) {
+      if (human_readable) {
+        st->print(PROPERFMT " ", PROPERFMTARGS(_peak_by_tag.counter(tag)));
+      } else {
+        st->print("%zu ", _peak_by_tag.counter(tag));
+      }
+      col += 10; st->fill_to(col);
     }
-    col += 10; st->fill_to(col);
 
     // result?
     st->print("%s ", _result ? _result : "");
@@ -296,7 +307,7 @@ class MemStatEntry : public CHeapObj<mtInternal> {
     col += 4; st->fill_to(col);
 
     // Thread
-    st->print(PTR_FORMAT "  ", p2i(_thread));
+    st->print(PTR_FORMAT " ", p2i(_thread));
 
     // MethodName
     char buf[1024];
@@ -341,7 +352,7 @@ class MemStatTable :
 public:
 
   void add(const FullMethodName& fmn, CompilerType comptype,
-           size_t total, size_t na_at_peak, size_t ra_at_peak,
+           size_t total, ArenaCountersByTag peak_by_tag,
            unsigned live_nodes_at_peak, size_t limit, const char* result) {
     assert_lock_strong(NMTCompilationCostHistory_lock);
     MemStatTableKey key(fmn, comptype);
@@ -360,8 +371,7 @@ class MemStatTable :
     e->set_comptype(comptype);
     e->inc_recompilation();
     e->set_total(total);
-    e->set_na_at_peak(na_at_peak);
-    e->set_ra_at_peak(ra_at_peak);
+    e->set_peak_by_tag(peak_by_tag);
     e->set_live_nodes_at_peak(live_nodes_at_peak);
     e->set_limit(limit);
     e->set_result(result);
@@ -427,7 +437,7 @@ void CompilationMemoryStatistic::on_end_compilation() {
   const bool print = directive->should_print_memstat();
 
   // Store memory used in task, for later processing by JFR
-  task->set_arena_bytes(arena_stat->peak_since_start());
+  task->set_arena_bytes(arena_stat->peak());
 
   // Store result
   // For this to work, we must call on_end_compilation() at a point where
@@ -447,9 +457,8 @@ void CompilationMemoryStatistic::on_end_compilation() {
     assert(_the_table != nullptr, "not initialized");
 
     _the_table->add(fmn, ct,
-                    arena_stat->peak_since_start(), // total
-                    arena_stat->na_at_peak(),
-                    arena_stat->ra_at_peak(),
+                    arena_stat->peak(), // total
+                    arena_stat->peak_by_tag(),
                     arena_stat->live_nodes_at_peak(),
                     arena_stat->limit(),
                     result);
@@ -511,7 +520,7 @@ void CompilationMemoryStatistic::on_arena_change(ssize_t diff, const Arena* aren
 
   bool hit_limit_before = arena_stat->hit_limit();
 
-  if (arena_stat->account(diff, (int)arena->get_tag())) { // new peak?
+  if (arena_stat->is_active() && arena_stat->account(diff, (int)arena->get_tag())) { // new peak?
 
     // Limit handling
     if (arena_stat->hit_limit()) {
@@ -545,7 +554,7 @@ void CompilationMemoryStatistic::on_arena_change(ssize_t diff, const Arena* aren
         }
         ss.print("Hit MemLimit %s(limit: %zu now: %zu)",
                  (hit_limit_before ? "again " : ""),
-                 arena_stat->limit(), arena_stat->peak_since_start());
+                 arena_stat->limit(), arena_stat->peak());
       }
 
       // log if needed
diff --git a/src/hotspot/share/compiler/compilationMemoryStatistic.hpp b/src/hotspot/share/compiler/compilationMemoryStatistic.hpp
index d7cccad17fd..d669cc14722 100644
--- a/src/hotspot/share/compiler/compilationMemoryStatistic.hpp
+++ b/src/hotspot/share/compiler/compilationMemoryStatistic.hpp
@@ -29,48 +29,70 @@
 #include "compiler/compilerDefinitions.hpp"
 #include "memory/allocation.hpp"
 #include "memory/allStatic.hpp"
+#include "memory/arena.hpp"
 #include "utilities/globalDefinitions.hpp"
 
 class outputStream;
 class Symbol;
 class DirectiveSet;
 
-// Counters for allocations from one arena
+// Helper class to wrap the array of arena tags for easier processing
+class ArenaCountersByTag {
+private:
+  size_t _counter[Arena::tag_count()];
+
+public:
+  int element_count() const { return Arena::tag_count(); }
+  const char* tag_name(int tag) const { return Arena::tag_name[tag]; }
+
+  size_t  counter(int tag) const {
+    assert(tag < element_count(), "invalid tag %d", tag);
+    return _counter[tag];
+  }
+
+  void add(int tag, size_t value) {
+    assert(tag < element_count(), "invalid tag %d", tag);
+    _counter[tag] += value;
+  }
+
+  void clear() {
+    memset(_counter, 0, sizeof(size_t) * element_count());
+  }
+};
+
+// Counters for allocations from arenas during compilation
 class ArenaStatCounter : public CHeapObj<mtCompiler> {
   // Current bytes, total
   size_t _current;
-  // bytes when compilation started
-  size_t _start;
   // bytes at last peak, total
   size_t _peak;
-  // Current bytes used for node arenas, total
-  size_t _na;
-  // Current bytes used for resource areas
-  size_t _ra;
+  // Current bytes used by arenas per tag
+  ArenaCountersByTag _current_by_tag;
+  // Peak composition:
+  ArenaCountersByTag _peak_by_tag;
   // MemLimit handling
   size_t _limit;
   bool _hit_limit;
   bool _limit_in_process;
 
-  // Peak composition:
-  // Size of node arena when total peaked (c2 only)
-  size_t _na_at_peak;
-  // Size of resource area when total peaked
-  size_t _ra_at_peak;
+  // When to start accounting
+  bool _active;
+
   // Number of live nodes when total peaked (c2 only)
   unsigned _live_nodes_at_peak;
 
   void update_c2_node_count();
 
+  void reset();
+
 public:
   ArenaStatCounter();
 
   // Size of peak since last compilation
-  size_t peak_since_start() const;
+  size_t peak() const { return _peak; }
 
   // Peak details
-  size_t na_at_peak() const { return _na_at_peak; }
-  size_t ra_at_peak() const { return _ra_at_peak; }
+  ArenaCountersByTag peak_by_tag() const { return _peak_by_tag; }
   unsigned live_nodes_at_peak() const { return _live_nodes_at_peak; }
 
   // Mark the start and end of a compilation.
@@ -89,7 +111,7 @@ class ArenaStatCounter : public CHeapObj<mtCompiler> {
   bool   hit_limit() const          { return _hit_limit; }
   bool   limit_in_process() const     { return _limit_in_process; }
   void   set_limit_in_process(bool v) { _limit_in_process = v; }
-
+  bool   is_active() const          { return _active; }
 };
 
 class CompilationMemoryStatistic : public AllStatic {
diff --git a/src/hotspot/share/gc/g1/g1ConcurrentRebuildAndScrub.cpp b/src/hotspot/share/gc/g1/g1ConcurrentRebuildAndScrub.cpp
index 35cff96eb93..f62d4206900 100644
--- a/src/hotspot/share/gc/g1/g1ConcurrentRebuildAndScrub.cpp
+++ b/src/hotspot/share/gc/g1/g1ConcurrentRebuildAndScrub.cpp
@@ -87,8 +87,9 @@ class G1RebuildRSAndScrubTask : public WorkerTask {
       _processed_words += processed;
     }
 
-    // Yield if enough has been processed; returns if the concurrent marking cycle
-    // has been aborted for any reason.
+    // Yield if enough has been processed. Return whether we should stop
+    // processing this region because either the concurrent marking cycle has been
+    // aborted or the region has been reclaimed.
     bool yield_if_necessary(G1HeapRegion* hr) {
       if (_processed_words >= ProcessingYieldLimitInWords) {
         reset_processed_words();
@@ -98,7 +99,7 @@ class G1RebuildRSAndScrubTask : public WorkerTask {
           return true;
         }
       }
-      return _cm->has_aborted();
+      return _cm->has_aborted() || !should_rebuild_or_scrub(hr);
     }
 
     // Returns whether the top at rebuild start value for the given region indicates
diff --git a/src/hotspot/share/gc/g1/g1_globals.hpp b/src/hotspot/share/gc/g1/g1_globals.hpp
index af1ac1f70c6..c8016ddc0dd 100644
--- a/src/hotspot/share/gc/g1/g1_globals.hpp
+++ b/src/hotspot/share/gc/g1/g1_globals.hpp
@@ -112,7 +112,7 @@
                                                                             \
   product(uint, G1ConfidencePercent, 50,                                    \
           "Confidence level for MMU/pause predictions")                     \
-          range(0, 100)                                                     \
+          range(1, 100)                                                     \
                                                                             \
   product(uintx, G1SummarizeRSetStatsPeriod, 0, DIAGNOSTIC,                 \
           "The period (in number of GCs) at which we will generate "        \
diff --git a/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.cpp b/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.cpp
index cfdb7e9eb29..288a21fd35d 100644
--- a/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.cpp
+++ b/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -205,8 +205,6 @@ void PSAdaptiveSizePolicy::compute_eden_space_size(
                                            bool   is_full_gc) {
 
   // Update statistics
-  // Time statistics are updated as we go, update footprint stats here
-  _avg_base_footprint->sample(BaseFootPrintEstimate);
   avg_young_live()->sample(young_live);
   avg_eden_live()->sample(eden_live);
 
@@ -363,8 +361,7 @@ void PSAdaptiveSizePolicy::compute_eden_space_size(
   log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT,
                       live_space(), free_space());
 
-  log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
-                      (size_t)_avg_base_footprint->average(),
+  log_trace(gc, ergo)("avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
                       (size_t)avg_young_live()->average(),
                       (size_t)avg_old_live()->average());
 
@@ -535,8 +532,7 @@ void PSAdaptiveSizePolicy::compute_old_gen_free_space(
   log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT,
                       live_space(), free_space());
 
-  log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
-                      (size_t)_avg_base_footprint->average(),
+  log_trace(gc, ergo)("avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
                       (size_t)avg_young_live()->average(),
                       (size_t)avg_old_live()->average());
 
diff --git a/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.hpp b/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.hpp
index 90e1e60db94..4fab160dcb4 100644
--- a/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.hpp
+++ b/src/hotspot/share/gc/parallel/psAdaptiveSizePolicy.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -145,8 +145,7 @@ class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {
 
   // Footprint accessors
   size_t live_space() const {
-    return (size_t)(avg_base_footprint()->average() +
-                    avg_young_live()->average() +
+    return (size_t)(avg_young_live()->average() +
                     avg_old_live()->average());
   }
   size_t free_space() const {
diff --git a/src/hotspot/share/gc/parallel/psCompactionManager.cpp b/src/hotspot/share/gc/parallel/psCompactionManager.cpp
index b95c7c619af..d9f2749230e 100644
--- a/src/hotspot/share/gc/parallel/psCompactionManager.cpp
+++ b/src/hotspot/share/gc/parallel/psCompactionManager.cpp
@@ -54,7 +54,9 @@ Monitor*                ParCompactionManager::_shadow_region_monitor = nullptr;
 
 PreservedMarksSet* ParCompactionManager::_preserved_marks_set = nullptr;
 
-ParCompactionManager::ParCompactionManager(PreservedMarks* preserved_marks) {
+ParCompactionManager::ParCompactionManager(PreservedMarks* preserved_marks,
+                                           ReferenceProcessor* ref_processor)
+  : _mark_and_push_closure(this, ref_processor) {
 
   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 
@@ -66,8 +68,9 @@ ParCompactionManager::ParCompactionManager(PreservedMarks* preserved_marks) {
 }
 
 void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
-  assert(ParallelScavengeHeap::heap() != nullptr,
-    "Needed for initialization");
+  assert(ParallelScavengeHeap::heap() != nullptr, "Needed for initialization");
+  assert(PSParallelCompact::ref_processor() != nullptr, "precondition");
+  assert(ParallelScavengeHeap::heap()->workers().max_workers() != 0, "Not initialized?");
 
   _mark_bitmap = mbm;
 
@@ -85,15 +88,13 @@ void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
 
   // Create and register the ParCompactionManager(s) for the worker threads.
   for(uint i=0; i<parallel_gc_threads; i++) {
-    _manager_array[i] = new ParCompactionManager(_preserved_marks_set->get(i));
+    _manager_array[i] = new ParCompactionManager(_preserved_marks_set->get(i),
+                                                 PSParallelCompact::ref_processor());
     oop_task_queues()->register_queue(i, _manager_array[i]->oop_stack());
     _objarray_task_queues->register_queue(i, &_manager_array[i]->_objarray_stack);
     region_task_queues()->register_queue(i, _manager_array[i]->region_stack());
   }
 
-  assert(ParallelScavengeHeap::heap()->workers().max_workers() != 0,
-    "Not initialized?");
-
   _shadow_region_array = new (mtGC) GrowableArray<size_t >(10, mtGC);
 
   _shadow_region_monitor = new Monitor(Mutex::nosafepoint, "CompactionManager_lock");
diff --git a/src/hotspot/share/gc/parallel/psCompactionManager.hpp b/src/hotspot/share/gc/parallel/psCompactionManager.hpp
index 0dd68d2e2f7..da1609a32d8 100644
--- a/src/hotspot/share/gc/parallel/psCompactionManager.hpp
+++ b/src/hotspot/share/gc/parallel/psCompactionManager.hpp
@@ -25,6 +25,7 @@
 #ifndef SHARE_GC_PARALLEL_PSCOMPACTIONMANAGER_HPP
 #define SHARE_GC_PARALLEL_PSCOMPACTIONMANAGER_HPP
 
+#include "classfile/classLoaderData.hpp"
 #include "gc/parallel/psParallelCompact.hpp"
 #include "gc/shared/preservedMarks.hpp"
 #include "gc/shared/stringdedup/stringDedup.hpp"
@@ -40,6 +41,19 @@ class ObjectStartArray;
 class ParallelCompactData;
 class ParMarkBitMap;
 
+class PCMarkAndPushClosure: public ClaimMetadataVisitingOopIterateClosure {
+  ParCompactionManager* _compaction_manager;
+
+  template <typename T> void do_oop_work(T* p);
+public:
+  PCMarkAndPushClosure(ParCompactionManager* cm, ReferenceProcessor* rp) :
+    ClaimMetadataVisitingOopIterateClosure(ClassLoaderData::_claim_stw_fullgc_mark, rp),
+    _compaction_manager(cm) { }
+
+  virtual void do_oop(oop* p)                     { do_oop_work(p); }
+  virtual void do_oop(narrowOop* p)               { do_oop_work(p); }
+};
+
 class ParCompactionManager : public CHeapObj<mtGC> {
   friend class MarkFromRootsTask;
   friend class ParallelCompactRefProcProxyTask;
@@ -47,6 +61,7 @@ class ParCompactionManager : public CHeapObj<mtGC> {
   friend class ParMarkBitMap;
   friend class PSParallelCompact;
   friend class FillDensePrefixAndCompactionTask;
+  friend class PCAddThreadRootsMarkingTaskClosure;
 
  private:
   typedef OverflowTaskQueue<oop, mtGC>            OopTaskQueue;
@@ -71,6 +86,7 @@ class ParCompactionManager : public CHeapObj<mtGC> {
   ObjArrayTaskQueue             _objarray_stack;
   size_t                        _next_shadow_region;
 
+  PCMarkAndPushClosure _mark_and_push_closure;
   // Is there a way to reuse the _oop_stack for the
   // saving empty regions?  For now just create a different
   // type of TaskQueue.
@@ -104,7 +120,9 @@ class ParCompactionManager : public CHeapObj<mtGC> {
   // objArray stack, otherwise returns false and the task is invalid.
   bool publish_or_pop_objarray_tasks(ObjArrayTask& task);
 
-  ParCompactionManager(PreservedMarks* preserved_marks);
+  ParCompactionManager(PreservedMarks* preserved_marks,
+                       ReferenceProcessor* ref_processor);
+
   // Array of task queues.  Needed by the task terminator.
   static RegionTaskQueueSet* region_task_queues()      { return _region_task_queues; }
   OopTaskQueue*  oop_stack()       { return &_oop_stack; }
diff --git a/src/hotspot/share/gc/parallel/psCompactionManager.inline.hpp b/src/hotspot/share/gc/parallel/psCompactionManager.inline.hpp
index 22acc11beec..0b928622238 100644
--- a/src/hotspot/share/gc/parallel/psCompactionManager.inline.hpp
+++ b/src/hotspot/share/gc/parallel/psCompactionManager.inline.hpp
@@ -41,29 +41,10 @@
 #include "utilities/debug.hpp"
 #include "utilities/globalDefinitions.hpp"
 
-class PCMarkAndPushClosure: public OopClosure {
-private:
-  ParCompactionManager* _compaction_manager;
-public:
-  PCMarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
-
-  template <typename T> void do_oop_work(T* p)      { _compaction_manager->mark_and_push(p); }
-  virtual void do_oop(oop* p)                     { do_oop_work(p); }
-  virtual void do_oop(narrowOop* p)               { do_oop_work(p); }
-};
-
-class PCIterateMarkAndPushClosure: public ClaimMetadataVisitingOopIterateClosure {
-private:
-  ParCompactionManager* _compaction_manager;
-public:
-  PCIterateMarkAndPushClosure(ParCompactionManager* cm, ReferenceProcessor* rp) :
-    ClaimMetadataVisitingOopIterateClosure(ClassLoaderData::_claim_stw_fullgc_mark, rp),
-    _compaction_manager(cm) { }
-
-  template <typename T> void do_oop_work(T* p)      { _compaction_manager->mark_and_push(p); }
-  virtual void do_oop(oop* p)                     { do_oop_work(p); }
-  virtual void do_oop(narrowOop* p)               { do_oop_work(p); }
-};
+template <typename T>
+inline void PCMarkAndPushClosure::do_oop_work(T* p) {
+  _compaction_manager->mark_and_push(p);
+}
 
 inline bool ParCompactionManager::steal(int queue_num, oop& t) {
   return oop_task_queues()->steal(queue_num, t);
@@ -161,13 +142,12 @@ inline void ParCompactionManager::follow_array(objArrayOop obj, int index) {
 
 inline void ParCompactionManager::follow_contents(oop obj) {
   assert(PSParallelCompact::mark_bitmap()->is_marked(obj), "should be marked");
-  PCIterateMarkAndPushClosure cl(this, PSParallelCompact::ref_processor());
 
   if (obj->is_objArray()) {
-    cl.do_klass(obj->klass());
+    _mark_and_push_closure.do_klass(obj->klass());
     follow_array(objArrayOop(obj), 0);
   } else {
-    obj->oop_iterate(&cl);
+    obj->oop_iterate(&_mark_and_push_closure);
   }
 }
 
diff --git a/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.cpp b/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.cpp
index 20e14b73ac3..ed96c5c4181 100644
--- a/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.cpp
+++ b/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -107,10 +107,6 @@ PSGCAdaptivePolicyCounters::PSGCAdaptivePolicyCounters(const char* name_arg,
     _free_space = PerfDataManager::create_variable(SUN_GC, cname,
       PerfData::U_Bytes, ps_size_policy()->free_space(), CHECK);
 
-    cname = PerfDataManager::counter_name(name_space(), "avgBaseFootprint");
-    _avg_base_footprint = PerfDataManager::create_variable(SUN_GC, cname,
-      PerfData::U_Bytes, (jlong) ps_size_policy()->avg_base_footprint()->average(), CHECK);
-
     cname = PerfDataManager::counter_name(name_space(), "liveAtLastFullGc");
     _live_at_last_full_gc_counter =
       PerfDataManager::create_variable(SUN_GC, cname,
@@ -157,7 +153,6 @@ void PSGCAdaptivePolicyCounters::update_counters_from_policy() {
     update_decrement_tenuring_threshold_for_survivor_limit();
     update_live_space();
     update_free_space();
-    update_avg_base_footprint();
 
     update_change_old_gen_for_maj_pauses();
     update_change_young_gen_for_maj_pauses();
diff --git a/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.hpp b/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.hpp
index 620c761004e..ad84eb4368b 100644
--- a/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.hpp
+++ b/src/hotspot/share/gc/parallel/psGCAdaptivePolicyCounters.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -50,7 +50,6 @@ class PSGCAdaptivePolicyCounters : public GCAdaptivePolicyCounters {
   PerfVariable* _avg_major_interval;
   PerfVariable* _live_space;
   PerfVariable* _free_space;
-  PerfVariable* _avg_base_footprint;
   PerfVariable* _live_at_last_full_gc_counter;
   PerfVariable* _old_capacity;
 
@@ -142,11 +141,6 @@ class PSGCAdaptivePolicyCounters : public GCAdaptivePolicyCounters {
     _free_space->set_value(ps_size_policy()->free_space());
   }
 
-  inline void update_avg_base_footprint() {
-    _avg_base_footprint->set_value(
-      (jlong)(ps_size_policy()->avg_base_footprint()->average())
-    );
-  }
   inline void update_avg_old_live() {
     _avg_old_live_counter->set_value(
       (jlong)(ps_size_policy()->avg_old_live()->average())
diff --git a/src/hotspot/share/gc/parallel/psParallelCompact.cpp b/src/hotspot/share/gc/parallel/psParallelCompact.cpp
index f41108d1a59..4d54f11805a 100644
--- a/src/hotspot/share/gc/parallel/psParallelCompact.cpp
+++ b/src/hotspot/share/gc/parallel/psParallelCompact.cpp
@@ -1188,10 +1188,11 @@ class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
 
     ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
 
-    PCMarkAndPushClosure mark_and_push_closure(cm);
-    MarkingNMethodClosure mark_and_push_in_blobs(&mark_and_push_closure, !NMethodToOopClosure::FixRelocations, true /* keepalive nmethods */);
+    MarkingNMethodClosure mark_and_push_in_blobs(&cm->_mark_and_push_closure,
+                                                 !NMethodToOopClosure::FixRelocations,
+                                                 true /* keepalive nmethods */);
 
-    thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
+    thread->oops_do(&cm->_mark_and_push_closure, &mark_and_push_in_blobs);
 
     // Do the real work
     cm->follow_marking_stacks();
@@ -1232,22 +1233,22 @@ class MarkFromRootsTask : public WorkerTask {
   virtual void work(uint worker_id) {
     ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
     cm->create_marking_stats_cache();
-    PCMarkAndPushClosure mark_and_push_closure(cm);
-
     {
-      CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
+      CLDToOopClosure cld_closure(&cm->_mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
       ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
 
       // Do the real work
       cm->follow_marking_stacks();
     }
 
-    PCAddThreadRootsMarkingTaskClosure closure(worker_id);
-    Threads::possibly_parallel_threads_do(true /* is_par */, &closure);
+    {
+      PCAddThreadRootsMarkingTaskClosure closure(worker_id);
+      Threads::possibly_parallel_threads_do(_active_workers > 1 /* is_par */, &closure);
+    }
 
     // Mark from OopStorages
     {
-      _oop_storage_set_par_state.oops_do(&mark_and_push_closure);
+      _oop_storage_set_par_state.oops_do(&cm->_mark_and_push_closure);
       // Do the real work
       cm->follow_marking_stacks();
     }
@@ -1269,10 +1270,9 @@ class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
   void work(uint worker_id) override {
     assert(worker_id < _max_workers, "sanity");
     ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
-    PCMarkAndPushClosure keep_alive(cm);
     BarrierEnqueueDiscoveredFieldClosure enqueue;
     ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
-    _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &keep_alive, &enqueue, &complete_gc);
+    _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &cm->_mark_and_push_closure, &enqueue, &complete_gc);
   }
 
   void prepare_run_task_hook() override {
diff --git a/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp b/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp
index d03f416ff68..c1485c069c8 100644
--- a/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp
+++ b/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp
@@ -102,10 +102,10 @@ class C2AccessValuePtr: public C2AccessValue {
 class C2Access: public StackObj {
 protected:
   DecoratorSet      _decorators;
-  BasicType         _type;
   Node*             _base;
   C2AccessValuePtr& _addr;
   Node*             _raw_access;
+  BasicType         _type;
   uint8_t           _barrier_data;
 
   void fixup_decorators();
@@ -114,10 +114,10 @@ class C2Access: public StackObj {
   C2Access(DecoratorSet decorators,
            BasicType type, Node* base, C2AccessValuePtr& addr) :
     _decorators(decorators),
-    _type(type),
     _base(base),
     _addr(addr),
     _raw_access(nullptr),
+    _type(type),
     _barrier_data(0)
   {}
 
diff --git a/src/hotspot/share/gc/shared/freeListAllocator.cpp b/src/hotspot/share/gc/shared/freeListAllocator.cpp
index f33c6fcb14b..ef7d12ab024 100644
--- a/src/hotspot/share/gc/shared/freeListAllocator.cpp
+++ b/src/hotspot/share/gc/shared/freeListAllocator.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -88,7 +88,7 @@ void FreeListAllocator::delete_list(FreeNode* list) {
 FreeListAllocator::~FreeListAllocator() {
   uint index = Atomic::load(&_active_pending_list);
   NodeList pending_list = _pending_lists[index].take_all();
-  delete_list(Atomic::load(&pending_list._head));
+  delete_list(pending_list._head);
   delete_list(_free_list.pop_all());
 }
 
@@ -106,7 +106,7 @@ size_t FreeListAllocator::free_count() const {
 
 size_t FreeListAllocator::pending_count() const {
   uint index = Atomic::load(&_active_pending_list);
-  return _pending_lists[index].count();;
+  return _pending_lists[index].count();
 }
 
 // To solve the ABA problem, popping a node from the _free_list is performed within
diff --git a/src/hotspot/share/gc/shared/gc_globals.hpp b/src/hotspot/share/gc/shared/gc_globals.hpp
index 66496544b96..34bc638c9ba 100644
--- a/src/hotspot/share/gc/shared/gc_globals.hpp
+++ b/src/hotspot/share/gc/shared/gc_globals.hpp
@@ -422,10 +422,6 @@
           "Initial ratio of young generation/survivor space size")          \
           range(0, max_uintx)                                               \
                                                                             \
-  product(size_t, BaseFootPrintEstimate, 256*M,                             \
-          "Estimate of footprint other than Java Heap")                     \
-          range(0, max_uintx)                                               \
-                                                                            \
   product(bool, UseGCOverheadLimit, true,                                   \
           "Use policy to limit of proportion of time spent in GC "          \
           "before an OutOfMemory error is thrown")                          \
diff --git a/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.cpp b/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.cpp
index 30bf1f7a395..6b104e7e199 100644
--- a/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.cpp
+++ b/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.cpp
@@ -183,20 +183,11 @@ LIR_Opr ShenandoahBarrierSetC1::ensure_in_register(LIRGenerator* gen, LIR_Opr ob
   return obj;
 }
 
-LIR_Opr ShenandoahBarrierSetC1::iu_barrier(LIRGenerator* gen, LIR_Opr obj, CodeEmitInfo* info, DecoratorSet decorators) {
-  if (ShenandoahIUBarrier) {
-    obj = ensure_in_register(gen, obj, T_OBJECT);
-    pre_barrier(gen, info, decorators, LIR_OprFact::illegalOpr, obj);
-  }
-  return obj;
-}
-
 void ShenandoahBarrierSetC1::store_at_resolved(LIRAccess& access, LIR_Opr value) {
   if (access.is_oop()) {
     if (ShenandoahSATBBarrier) {
       pre_barrier(access.gen(), access.access_emit_info(), access.decorators(), access.resolved_addr(), LIR_OprFact::illegalOpr /* pre_val */);
     }
-    value = iu_barrier(access.gen(), value, access.access_emit_info(), access.decorators());
   }
   BarrierSetC1::store_at_resolved(access, value);
 }
diff --git a/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.hpp b/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.hpp
index 71093300e82..98b2aad8871 100644
--- a/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.hpp
+++ b/src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.hpp
@@ -200,7 +200,6 @@ class ShenandoahBarrierSetC1 : public BarrierSetC1 {
   void pre_barrier(LIRGenerator* gen, CodeEmitInfo* info, DecoratorSet decorators, LIR_Opr addr_opr, LIR_Opr pre_val);
 
   LIR_Opr load_reference_barrier(LIRGenerator* gen, LIR_Opr obj, LIR_Opr addr, DecoratorSet decorators);
-  LIR_Opr iu_barrier(LIRGenerator* gen, LIR_Opr obj, CodeEmitInfo* info, DecoratorSet decorators);
 
   LIR_Opr load_reference_barrier_impl(LIRGenerator* gen, LIR_Opr obj, LIR_Opr addr, DecoratorSet decorators);
 
diff --git a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
index 7d1f5cc16a8..d2820f3aa26 100644
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
@@ -48,25 +48,7 @@ ShenandoahBarrierSetC2* ShenandoahBarrierSetC2::bsc2() {
 }
 
 ShenandoahBarrierSetC2State::ShenandoahBarrierSetC2State(Arena* comp_arena)
-  : _iu_barriers(new (comp_arena) GrowableArray<ShenandoahIUBarrierNode*>(comp_arena, 8,  0, nullptr)),
-    _load_reference_barriers(new (comp_arena) GrowableArray<ShenandoahLoadReferenceBarrierNode*>(comp_arena, 8,  0, nullptr)) {
-}
-
-int ShenandoahBarrierSetC2State::iu_barriers_count() const {
-  return _iu_barriers->length();
-}
-
-ShenandoahIUBarrierNode* ShenandoahBarrierSetC2State::iu_barrier(int idx) const {
-  return _iu_barriers->at(idx);
-}
-
-void ShenandoahBarrierSetC2State::add_iu_barrier(ShenandoahIUBarrierNode* n) {
-  assert(!_iu_barriers->contains(n), "duplicate entry in barrier list");
-  _iu_barriers->append(n);
-}
-
-void ShenandoahBarrierSetC2State::remove_iu_barrier(ShenandoahIUBarrierNode* n) {
-  _iu_barriers->remove_if_existing(n);
+  : _load_reference_barriers(new (comp_arena) GrowableArray<ShenandoahLoadReferenceBarrierNode*>(comp_arena, 8,  0, nullptr)) {
 }
 
 int ShenandoahBarrierSetC2State::load_reference_barriers_count() const {
@@ -88,13 +70,6 @@ void ShenandoahBarrierSetC2State::remove_load_reference_barrier(ShenandoahLoadRe
   }
 }
 
-Node* ShenandoahBarrierSetC2::shenandoah_iu_barrier(GraphKit* kit, Node* obj) const {
-  if (ShenandoahIUBarrier) {
-    return kit->gvn().transform(new ShenandoahIUBarrierNode(obj));
-  }
-  return obj;
-}
-
 #define __ kit->
 
 bool ShenandoahBarrierSetC2::satb_can_remove_pre_barrier(GraphKit* kit, PhaseValues* phase, Node* adr,
@@ -508,21 +483,8 @@ Node* ShenandoahBarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue&
 
     uint adr_idx = kit->C->get_alias_index(adr_type);
     assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory" );
-    Node* value = val.node();
-    value = shenandoah_iu_barrier(kit, value);
-    val.set_node(value);
     shenandoah_write_barrier_pre(kit, true /* do_load */, /*kit->control(),*/ access.base(), adr, adr_idx, val.node(),
                                  static_cast<const TypeOopPtr*>(val.type()), nullptr /* pre_val */, access.type());
-  } else {
-    assert(access.is_opt_access(), "only for optimization passes");
-    assert(((decorators & C2_TIGHTLY_COUPLED_ALLOC) != 0 || !ShenandoahSATBBarrier) && (decorators & C2_ARRAY_COPY) != 0, "unexpected caller of this code");
-    C2OptAccess& opt_access = static_cast<C2OptAccess&>(access);
-    PhaseGVN& gvn =  opt_access.gvn();
-
-    if (ShenandoahIUBarrier) {
-      Node* enqueue = gvn.transform(new ShenandoahIUBarrierNode(val.node()));
-      val.set_node(enqueue);
-    }
   }
   return BarrierSetC2::store_at_resolved(access, val);
 }
@@ -598,7 +560,6 @@ Node* ShenandoahBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess
                                                    Node* new_val, const Type* value_type) const {
   GraphKit* kit = access.kit();
   if (access.is_oop()) {
-    new_val = shenandoah_iu_barrier(kit, new_val);
     shenandoah_write_barrier_pre(kit, false /* do_load */,
                                  nullptr, nullptr, max_juint, nullptr, nullptr,
                                  expected_val /* pre_val */, T_OBJECT);
@@ -646,7 +607,6 @@ Node* ShenandoahBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAcces
                                                               Node* new_val, const Type* value_type) const {
   GraphKit* kit = access.kit();
   if (access.is_oop()) {
-    new_val = shenandoah_iu_barrier(kit, new_val);
     shenandoah_write_barrier_pre(kit, false /* do_load */,
                                  nullptr, nullptr, max_juint, nullptr, nullptr,
                                  expected_val /* pre_val */, T_OBJECT);
@@ -699,9 +659,6 @@ Node* ShenandoahBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAcces
 
 Node* ShenandoahBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* val, const Type* value_type) const {
   GraphKit* kit = access.kit();
-  if (access.is_oop()) {
-    val = shenandoah_iu_barrier(kit, val);
-  }
   Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, val, value_type);
   if (access.is_oop()) {
     result = kit->gvn().transform(new ShenandoahLoadReferenceBarrierNode(nullptr, result, access.decorators()));
@@ -719,7 +676,7 @@ bool ShenandoahBarrierSetC2::is_gc_pre_barrier_node(Node* node) const {
 
 // Support for GC barriers emitted during parsing
 bool ShenandoahBarrierSetC2::is_gc_barrier_node(Node* node) const {
-  if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier || node->Opcode() == Op_ShenandoahIUBarrier) return true;
+  if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) return true;
   if (node->Opcode() != Op_CallLeaf && node->Opcode() != Op_CallLeafNoFP) {
     return false;
   }
@@ -740,9 +697,6 @@ Node* ShenandoahBarrierSetC2::step_over_gc_barrier(Node* c) const {
   if (c->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
     return c->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
   }
-  if (c->Opcode() == Op_ShenandoahIUBarrier) {
-    c = c->in(1);
-  }
   return c;
 }
 
@@ -775,9 +729,6 @@ bool ShenandoahBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_couple
     }
     return !is_clone;
   }
-  if (phase == Optimization) {
-    return !ShenandoahIUBarrier;
-  }
   return true;
 }
 
@@ -836,11 +787,7 @@ void ShenandoahBarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCo
     debug_only(gc_state_adr_type = phase->C->get_adr_type(gc_state_idx));
 
     Node* gc_state    = phase->transform_later(new LoadBNode(ctrl, mem, gc_state_addr, gc_state_adr_type, TypeInt::BYTE, MemNode::unordered));
-    int flags = ShenandoahHeap::HAS_FORWARDED;
-    if (ShenandoahIUBarrier) {
-      flags |= ShenandoahHeap::MARKING;
-    }
-    Node* stable_and  = phase->transform_later(new AndINode(gc_state, phase->igvn().intcon(flags)));
+    Node* stable_and  = phase->transform_later(new AndINode(gc_state, phase->igvn().intcon(ShenandoahHeap::HAS_FORWARDED)));
     Node* stable_cmp  = phase->transform_later(new CmpINode(stable_and, phase->igvn().zerocon(T_INT)));
     Node* stable_test = phase->transform_later(new BoolNode(stable_cmp, BoolTest::ne));
 
@@ -889,18 +836,12 @@ void ShenandoahBarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCo
 
 // Support for macro expanded GC barriers
 void ShenandoahBarrierSetC2::register_potential_barrier_node(Node* node) const {
-  if (node->Opcode() == Op_ShenandoahIUBarrier) {
-    state()->add_iu_barrier((ShenandoahIUBarrierNode*) node);
-  }
   if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
     state()->add_load_reference_barrier((ShenandoahLoadReferenceBarrierNode*) node);
   }
 }
 
 void ShenandoahBarrierSetC2::unregister_potential_barrier_node(Node* node) const {
-  if (node->Opcode() == Op_ShenandoahIUBarrier) {
-    state()->remove_iu_barrier((ShenandoahIUBarrierNode*) node);
-  }
   if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
     state()->remove_load_reference_barrier((ShenandoahLoadReferenceBarrierNode*) node);
   }
@@ -948,12 +889,7 @@ void ShenandoahBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &use
       }
     }
   }
-  for (int i = state()->iu_barriers_count() - 1; i >= 0; i--) {
-    ShenandoahIUBarrierNode* n = state()->iu_barrier(i);
-    if (!useful.member(n)) {
-      state()->remove_iu_barrier(n);
-    }
-  }
+
   for (int i = state()->load_reference_barriers_count() - 1; i >= 0; i--) {
     ShenandoahLoadReferenceBarrierNode* n = state()->load_reference_barrier(i);
     if (!useful.member(n)) {
@@ -1190,9 +1126,6 @@ bool ShenandoahBarrierSetC2::escape_add_to_con_graph(ConnectionGraph* conn_graph
       }
       return false;
     }
-    case Op_ShenandoahIUBarrier:
-      conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), delayed_worklist);
-      break;
     case Op_ShenandoahLoadReferenceBarrier:
       conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), delayed_worklist);
       return true;
@@ -1216,9 +1149,6 @@ bool ShenandoahBarrierSetC2::escape_add_final_edges(ConnectionGraph* conn_graph,
     case Op_ShenandoahWeakCompareAndSwapP:
     case Op_ShenandoahWeakCompareAndSwapN:
       return conn_graph->add_final_edges_unsafe_access(n, opcode);
-    case Op_ShenandoahIUBarrier:
-      conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), nullptr);
-      return true;
     case Op_ShenandoahLoadReferenceBarrier:
       conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), nullptr);
       return true;
diff --git a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.hpp b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.hpp
index 9b8e30c98a1..4619b217e96 100644
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.hpp
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.hpp
@@ -31,17 +31,11 @@
 
 class ShenandoahBarrierSetC2State : public ArenaObj {
 private:
-  GrowableArray<ShenandoahIUBarrierNode*>* _iu_barriers;
   GrowableArray<ShenandoahLoadReferenceBarrierNode*>* _load_reference_barriers;
 
 public:
   ShenandoahBarrierSetC2State(Arena* comp_arena);
 
-  int iu_barriers_count() const;
-  ShenandoahIUBarrierNode* iu_barrier(int idx) const;
-  void add_iu_barrier(ShenandoahIUBarrierNode* n);
-  void remove_iu_barrier(ShenandoahIUBarrierNode * n);
-
   int load_reference_barriers_count() const;
   ShenandoahLoadReferenceBarrierNode* load_reference_barrier(int idx) const;
   void add_load_reference_barrier(ShenandoahLoadReferenceBarrierNode* n);
@@ -73,8 +67,6 @@ class ShenandoahBarrierSetC2 : public BarrierSetC2 {
                                     Node* pre_val,
                                     BasicType bt) const;
 
-  Node* shenandoah_iu_barrier(GraphKit* kit, Node* obj) const;
-
   void insert_pre_barrier(GraphKit* kit, Node* base_oop, Node* offset,
                           Node* pre_val, bool need_mem_bar) const;
 
diff --git a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp
index 8cd76dd3d6b..0a51f742995 100644
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp
@@ -46,8 +46,7 @@
 
 bool ShenandoahBarrierC2Support::expand(Compile* C, PhaseIterGVN& igvn) {
   ShenandoahBarrierSetC2State* state = ShenandoahBarrierSetC2::bsc2()->state();
-  if ((state->iu_barriers_count() +
-       state->load_reference_barriers_count()) > 0) {
+  if (state->load_reference_barriers_count() > 0) {
     assert(C->post_loop_opts_phase(), "no loop opts allowed");
     C->reset_post_loop_opts_phase(); // ... but we know what we are doing
     C->clear_major_progress();
@@ -186,28 +185,10 @@ bool ShenandoahBarrierC2Support::verify_helper(Node* in, Node_Stack& phis, Vecto
         }
       } else if (in->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
         if (t == ShenandoahOopStore) {
-          uint i = 0;
-          for (; i < phis.size(); i++) {
-            Node* n = phis.node_at(i);
-            if (n->Opcode() == Op_ShenandoahIUBarrier) {
-              break;
-            }
-          }
-          if (i == phis.size()) {
-            return false;
-          }
+          return false;
         }
         barriers_used.push(in);
         if (trace) {tty->print("Found barrier"); in->dump();}
-      } else if (in->Opcode() == Op_ShenandoahIUBarrier) {
-        if (t != ShenandoahOopStore) {
-          in = in->in(1);
-          continue;
-        }
-        if (trace) {tty->print("Found enqueue barrier"); in->dump();}
-        phis.push(in, in->req());
-        in = in->in(1);
-        continue;
       } else if (in->is_Proj() && in->in(0)->is_Allocate()) {
         if (trace) {
           tty->print("Found alloc");
@@ -326,7 +307,7 @@ void ShenandoahBarrierC2Support::verify(RootNode* root) {
           }
         }
 
-        if (verify && !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahIUBarrier ? ShenandoahOopStore : ShenandoahValue, trace, barriers_used)) {
+        if (verify && !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahValue, trace, barriers_used)) {
           report_verify_failure("Shenandoah verification: Store should have barriers", n);
         }
       }
@@ -368,7 +349,7 @@ void ShenandoahBarrierC2Support::verify(RootNode* root) {
       }
     } else if (n->is_LoadStore()) {
       if (n->in(MemNode::ValueIn)->bottom_type()->make_ptr() &&
-          !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahIUBarrier ? ShenandoahOopStore : ShenandoahValue, trace, barriers_used)) {
+          !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahValue, trace, barriers_used)) {
         report_verify_failure("Shenandoah verification: LoadStore (value) should have barriers", n);
       }
 
@@ -532,7 +513,7 @@ void ShenandoahBarrierC2Support::verify(RootNode* root) {
           }
         }
       }
-    } else if (n->Opcode() == Op_ShenandoahIUBarrier || n->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
+    } else if (n->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
       // skip
     } else if (n->is_AddP()
                || n->is_Phi()
@@ -1113,20 +1094,6 @@ void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
   ShenandoahBarrierSetC2State* state = ShenandoahBarrierSetC2::bsc2()->state();
 
   Unique_Node_List uses;
-  for (int i = 0; i < state->iu_barriers_count(); i++) {
-    Node* barrier = state->iu_barrier(i);
-    Node* ctrl = phase->get_ctrl(barrier);
-    IdealLoopTree* loop = phase->get_loop(ctrl);
-    Node* head = loop->head();
-    if (head->is_OuterStripMinedLoop()) {
-      // Expanding a barrier here will break loop strip mining
-      // verification. Transform the loop so the loop nest doesn't
-      // appear as strip mined.
-      OuterStripMinedLoopNode* outer = head->as_OuterStripMinedLoop();
-      hide_strip_mined_loop(outer, outer->unique_ctrl_out()->as_CountedLoop(), phase);
-    }
-  }
-
   Node_Stack stack(0);
   Node_List clones;
   for (int i = state->load_reference_barriers_count() - 1; i >= 0; i--) {
@@ -1459,157 +1426,6 @@ void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
   }
   // Done expanding load-reference-barriers.
   assert(ShenandoahBarrierSetC2::bsc2()->state()->load_reference_barriers_count() == 0, "all load reference barrier nodes should have been replaced");
-
-  for (int i = state->iu_barriers_count() - 1; i >= 0; i--) {
-    Node* barrier = state->iu_barrier(i);
-    Node* pre_val = barrier->in(1);
-
-    if (phase->igvn().type(pre_val)->higher_equal(TypePtr::NULL_PTR)) {
-      ShouldNotReachHere();
-      continue;
-    }
-
-    Node* ctrl = phase->get_ctrl(barrier);
-
-    if (ctrl->is_Proj() && ctrl->in(0)->is_CallJava()) {
-      assert(is_dominator(phase->get_ctrl(pre_val), ctrl->in(0)->in(0), pre_val, ctrl->in(0), phase), "can't move");
-      ctrl = ctrl->in(0)->in(0);
-      phase->set_ctrl(barrier, ctrl);
-    } else if (ctrl->is_CallRuntime()) {
-      assert(is_dominator(phase->get_ctrl(pre_val), ctrl->in(0), pre_val, ctrl, phase), "can't move");
-      ctrl = ctrl->in(0);
-      phase->set_ctrl(barrier, ctrl);
-    }
-
-    Node* init_ctrl = ctrl;
-    IdealLoopTree* loop = phase->get_loop(ctrl);
-    Node* raw_mem = fixer.find_mem(ctrl, barrier);
-    Node* init_raw_mem = raw_mem;
-    Node* raw_mem_for_ctrl = fixer.find_mem(ctrl, nullptr);
-    Node* heap_stable_ctrl = nullptr;
-    Node* null_ctrl = nullptr;
-    uint last = phase->C->unique();
-
-    enum { _heap_stable = 1, _heap_unstable, PATH_LIMIT };
-    Node* region = new RegionNode(PATH_LIMIT);
-    Node* phi = PhiNode::make(region, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
-
-    enum { _fast_path = 1, _slow_path, _null_path, PATH_LIMIT2 };
-    Node* region2 = new RegionNode(PATH_LIMIT2);
-    Node* phi2 = PhiNode::make(region2, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
-
-    // Stable path.
-    test_gc_state(ctrl, raw_mem, heap_stable_ctrl, phase, ShenandoahHeap::MARKING);
-    region->init_req(_heap_stable, heap_stable_ctrl);
-    phi->init_req(_heap_stable, raw_mem);
-
-    // Null path
-    Node* reg2_ctrl = nullptr;
-    test_null(ctrl, pre_val, null_ctrl, phase);
-    if (null_ctrl != nullptr) {
-      reg2_ctrl = null_ctrl->in(0);
-      region2->init_req(_null_path, null_ctrl);
-      phi2->init_req(_null_path, raw_mem);
-    } else {
-      region2->del_req(_null_path);
-      phi2->del_req(_null_path);
-    }
-
-    const int index_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset());
-    const int buffer_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
-    Node* thread = new ThreadLocalNode();
-    phase->register_new_node(thread, ctrl);
-    Node* buffer_adr = new AddPNode(phase->C->top(), thread, phase->igvn().MakeConX(buffer_offset));
-    phase->register_new_node(buffer_adr, ctrl);
-    Node* index_adr = new AddPNode(phase->C->top(), thread, phase->igvn().MakeConX(index_offset));
-    phase->register_new_node(index_adr, ctrl);
-
-    BasicType index_bt = TypeX_X->basic_type();
-    assert(sizeof(size_t) == type2aelembytes(index_bt), "Loading Shenandoah SATBMarkQueue::_index with wrong size.");
-    const TypePtr* adr_type = TypeRawPtr::BOTTOM;
-    Node* index = new LoadXNode(ctrl, raw_mem, index_adr, adr_type, TypeX_X, MemNode::unordered);
-    phase->register_new_node(index, ctrl);
-    Node* index_cmp = new CmpXNode(index, phase->igvn().MakeConX(0));
-    phase->register_new_node(index_cmp, ctrl);
-    Node* index_test = new BoolNode(index_cmp, BoolTest::ne);
-    phase->register_new_node(index_test, ctrl);
-    IfNode* queue_full_iff = new IfNode(ctrl, index_test, PROB_LIKELY(0.999), COUNT_UNKNOWN);
-    if (reg2_ctrl == nullptr) reg2_ctrl = queue_full_iff;
-    phase->register_control(queue_full_iff, loop, ctrl);
-    Node* not_full = new IfTrueNode(queue_full_iff);
-    phase->register_control(not_full, loop, queue_full_iff);
-    Node* full = new IfFalseNode(queue_full_iff);
-    phase->register_control(full, loop, queue_full_iff);
-
-    ctrl = not_full;
-
-    Node* next_index = new SubXNode(index, phase->igvn().MakeConX(sizeof(intptr_t)));
-    phase->register_new_node(next_index, ctrl);
-
-    Node* buffer  = new LoadPNode(ctrl, raw_mem, buffer_adr, adr_type, TypeRawPtr::NOTNULL, MemNode::unordered);
-    phase->register_new_node(buffer, ctrl);
-    Node *log_addr = new AddPNode(phase->C->top(), buffer, next_index);
-    phase->register_new_node(log_addr, ctrl);
-    Node* log_store = new StorePNode(ctrl, raw_mem, log_addr, adr_type, pre_val, MemNode::unordered);
-    phase->register_new_node(log_store, ctrl);
-    // update the index
-    Node* index_update = new StoreXNode(ctrl, log_store, index_adr, adr_type, next_index, MemNode::unordered);
-    phase->register_new_node(index_update, ctrl);
-
-    // Fast-path case
-    region2->init_req(_fast_path, ctrl);
-    phi2->init_req(_fast_path, index_update);
-
-    ctrl = full;
-
-    Node* base = find_bottom_mem(ctrl, phase);
-
-    MergeMemNode* mm = MergeMemNode::make(base);
-    mm->set_memory_at(Compile::AliasIdxRaw, raw_mem);
-    phase->register_new_node(mm, ctrl);
-
-    Node* call = new CallLeafNode(ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type(), CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), "shenandoah_wb_pre", TypeRawPtr::BOTTOM);
-    call->init_req(TypeFunc::Control, ctrl);
-    call->init_req(TypeFunc::I_O, phase->C->top());
-    call->init_req(TypeFunc::Memory, mm);
-    call->init_req(TypeFunc::FramePtr, phase->C->top());
-    call->init_req(TypeFunc::ReturnAdr, phase->C->top());
-    call->init_req(TypeFunc::Parms, pre_val);
-    call->init_req(TypeFunc::Parms+1, thread);
-    phase->register_control(call, loop, ctrl);
-
-    Node* ctrl_proj = new ProjNode(call, TypeFunc::Control);
-    phase->register_control(ctrl_proj, loop, call);
-    Node* mem_proj = new ProjNode(call, TypeFunc::Memory);
-    phase->register_new_node(mem_proj, call);
-
-    // Slow-path case
-    region2->init_req(_slow_path, ctrl_proj);
-    phi2->init_req(_slow_path, mem_proj);
-
-    phase->register_control(region2, loop, reg2_ctrl);
-    phase->register_new_node(phi2, region2);
-
-    region->init_req(_heap_unstable, region2);
-    phi->init_req(_heap_unstable, phi2);
-
-    phase->register_control(region, loop, heap_stable_ctrl->in(0));
-    phase->register_new_node(phi, region);
-
-    fix_ctrl(barrier, region, fixer, uses, uses_to_ignore, last, phase);
-    for(uint next = 0; next < uses.size(); next++ ) {
-      Node *n = uses.at(next);
-      assert(phase->get_ctrl(n) == init_ctrl, "bad control");
-      assert(n != init_raw_mem, "should leave input raw mem above the barrier");
-      phase->set_ctrl(n, region);
-      follow_barrier_uses(n, init_ctrl, uses, phase);
-    }
-    fixer.fix_mem(init_ctrl, region, init_raw_mem, raw_mem_for_ctrl, phi, uses);
-
-    phase->igvn().replace_node(barrier, pre_val);
-  }
-  assert(state->iu_barriers_count() == 0, "all enqueue barrier nodes should have been replaced");
-
 }
 
 Node* ShenandoahBarrierC2Support::get_load_addr(PhaseIdealLoop* phase, VectorSet& visited, Node* in) {
@@ -1662,8 +1478,6 @@ Node* ShenandoahBarrierC2Support::get_load_addr(PhaseIdealLoop* phase, VectorSet
     }
     case Op_ShenandoahLoadReferenceBarrier:
       return get_load_addr(phase, visited, in->in(ShenandoahLoadReferenceBarrierNode::ValueIn));
-    case Op_ShenandoahIUBarrier:
-      return get_load_addr(phase, visited, in->in(1));
     case Op_CallDynamicJava:
     case Op_CallLeaf:
     case Op_CallStaticJava:
@@ -1911,126 +1725,6 @@ void ShenandoahBarrierC2Support::optimize_after_expansion(VectorSet &visited, No
   }
 }
 
-ShenandoahIUBarrierNode::ShenandoahIUBarrierNode(Node* val) : Node(nullptr, val) {
-  ShenandoahBarrierSetC2::bsc2()->state()->add_iu_barrier(this);
-}
-
-const Type* ShenandoahIUBarrierNode::bottom_type() const {
-  if (in(1) == nullptr || in(1)->is_top()) {
-    return Type::TOP;
-  }
-  const Type* t = in(1)->bottom_type();
-  if (t == TypePtr::NULL_PTR) {
-    return t;
-  }
-  return t->is_oopptr();
-}
-
-const Type* ShenandoahIUBarrierNode::Value(PhaseGVN* phase) const {
-  if (in(1) == nullptr) {
-    return Type::TOP;
-  }
-  const Type* t = phase->type(in(1));
-  if (t == Type::TOP) {
-    return Type::TOP;
-  }
-  if (t == TypePtr::NULL_PTR) {
-    return t;
-  }
-  return t->is_oopptr();
-}
-
-int ShenandoahIUBarrierNode::needed(Node* n) {
-  if (n == nullptr ||
-      n->is_Allocate() ||
-      n->Opcode() == Op_ShenandoahIUBarrier ||
-      n->bottom_type() == TypePtr::NULL_PTR ||
-      (n->bottom_type()->make_oopptr() != nullptr && n->bottom_type()->make_oopptr()->const_oop() != nullptr)) {
-    return NotNeeded;
-  }
-  if (n->is_Phi() ||
-      n->is_CMove()) {
-    return MaybeNeeded;
-  }
-  return Needed;
-}
-
-Node* ShenandoahIUBarrierNode::next(Node* n) {
-  for (;;) {
-    if (n == nullptr) {
-      return n;
-    } else if (n->bottom_type() == TypePtr::NULL_PTR) {
-      return n;
-    } else if (n->bottom_type()->make_oopptr() != nullptr && n->bottom_type()->make_oopptr()->const_oop() != nullptr) {
-      return n;
-    } else if (n->is_ConstraintCast() ||
-               n->Opcode() == Op_DecodeN ||
-               n->Opcode() == Op_EncodeP) {
-      n = n->in(1);
-    } else if (n->is_Proj()) {
-      n = n->in(0);
-    } else {
-      return n;
-    }
-  }
-  ShouldNotReachHere();
-  return nullptr;
-}
-
-Node* ShenandoahIUBarrierNode::Identity(PhaseGVN* phase) {
-  PhaseIterGVN* igvn = phase->is_IterGVN();
-
-  Node* n = next(in(1));
-
-  int cont = needed(n);
-
-  if (cont == NotNeeded) {
-    return in(1);
-  } else if (cont == MaybeNeeded) {
-    if (igvn == nullptr) {
-      phase->record_for_igvn(this);
-      return this;
-    } else {
-      ResourceMark rm;
-      Unique_Node_List wq;
-      uint wq_i = 0;
-
-      for (;;) {
-        if (n->is_Phi()) {
-          for (uint i = 1; i < n->req(); i++) {
-            Node* m = n->in(i);
-            if (m != nullptr) {
-              wq.push(m);
-            }
-          }
-        } else {
-          assert(n->is_CMove(), "nothing else here");
-          Node* m = n->in(CMoveNode::IfFalse);
-          wq.push(m);
-          m = n->in(CMoveNode::IfTrue);
-          wq.push(m);
-        }
-        Node* orig_n = nullptr;
-        do {
-          if (wq_i >= wq.size()) {
-            return in(1);
-          }
-          n = wq.at(wq_i);
-          wq_i++;
-          orig_n = n;
-          n = next(n);
-          cont = needed(n);
-          if (cont == Needed) {
-            return this;
-          }
-        } while (cont != MaybeNeeded || (orig_n != n && wq.member(n)));
-      }
-    }
-  }
-
-  return this;
-}
-
 #ifdef ASSERT
 static bool has_never_branch(Node* root) {
   for (uint i = 1; i < root->req(); i++) {
@@ -3014,8 +2708,6 @@ bool ShenandoahLoadReferenceBarrierNode::needs_barrier_impl(PhaseGVN* phase, Nod
     case Op_CMoveP:
       return needs_barrier_impl(phase, n->in(2), visited) ||
              needs_barrier_impl(phase, n->in(3), visited);
-    case Op_ShenandoahIUBarrier:
-      return needs_barrier_impl(phase, n->in(1), visited);
     case Op_CreateEx:
       return false;
     default:
diff --git a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp
index 7a6ed74f563..164502e6358 100644
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp
@@ -87,23 +87,6 @@ class ShenandoahBarrierC2Support : public AllStatic {
 #endif
 };
 
-class ShenandoahIUBarrierNode : public Node {
-public:
-  ShenandoahIUBarrierNode(Node* val);
-
-  const Type *bottom_type() const;
-  const Type* Value(PhaseGVN* phase) const;
-  Node* Identity(PhaseGVN* phase);
-
-  int Opcode() const;
-
-private:
-  enum { Needed, NotNeeded, MaybeNeeded };
-
-  static int needed(Node* n);
-  static Node* next(Node* n);
-};
-
 class MemoryGraphFixer : public ResourceObj {
 private:
   Node_List _memory_nodes;
diff --git a/src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.cpp b/src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.cpp
deleted file mode 100644
index 7a1cf1bbbdf..00000000000
--- a/src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.cpp
+++ /dev/null
@@ -1,82 +0,0 @@
-/*
- * Copyright (c) 2020, 2022, Red Hat, Inc. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#include "precompiled.hpp"
-#include "gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.hpp"
-#include "gc/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
-#include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
-#include "gc/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
-#include "gc/shenandoah/mode/shenandoahIUMode.hpp"
-#include "gc/shenandoah/shenandoahHeap.inline.hpp"
-#include "logging/log.hpp"
-#include "logging/logTag.hpp"
-#include "runtime/globals_extension.hpp"
-#include "runtime/java.hpp"
-
-void ShenandoahIUMode::initialize_flags() const {
-  if (FLAG_IS_CMDLINE(ClassUnloadingWithConcurrentMark) && ClassUnloading) {
-    log_warning(gc)("Shenandoah I-U mode sets -XX:-ClassUnloadingWithConcurrentMark; see JDK-8261341 for details");
-  }
-  FLAG_SET_DEFAULT(ClassUnloadingWithConcurrentMark, false);
-
-  if (ClassUnloading) {
-    FLAG_SET_DEFAULT(VerifyBeforeExit, false);
-  }
-
-  if (FLAG_IS_DEFAULT(ShenandoahIUBarrier)) {
-    FLAG_SET_DEFAULT(ShenandoahIUBarrier, true);
-  }
-  if (FLAG_IS_DEFAULT(ShenandoahSATBBarrier)) {
-    FLAG_SET_DEFAULT(ShenandoahSATBBarrier, false);
-  }
-
-  SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
-  SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
-
-  // Final configuration checks
-  SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
-  SHENANDOAH_CHECK_FLAG_UNSET(ShenandoahSATBBarrier);
-  SHENANDOAH_CHECK_FLAG_SET(ShenandoahIUBarrier);
-  SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
-  SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
-  SHENANDOAH_CHECK_FLAG_SET(ShenandoahStackWatermarkBarrier);
-}
-
-ShenandoahHeuristics* ShenandoahIUMode::initialize_heuristics() const {
-  if (ShenandoahGCHeuristics == nullptr) {
-    vm_exit_during_initialization("Unknown -XX:ShenandoahGCHeuristics option (null)");
-  }
-  ShenandoahHeap* heap = ShenandoahHeap::heap();
-  if (strcmp(ShenandoahGCHeuristics, "aggressive") == 0) {
-    return new ShenandoahAggressiveHeuristics(heap);
-  } else if (strcmp(ShenandoahGCHeuristics, "static") == 0) {
-    return new ShenandoahStaticHeuristics(heap);
-  } else if (strcmp(ShenandoahGCHeuristics, "adaptive") == 0) {
-    return new ShenandoahAdaptiveHeuristics(heap);
-  } else if (strcmp(ShenandoahGCHeuristics, "compact") == 0) {
-    return new ShenandoahCompactHeuristics(heap);
-  }
-  vm_exit_during_initialization("Unknown -XX:ShenandoahGCHeuristics option");
-  return nullptr;
-}
diff --git a/src/hotspot/share/gc/shenandoah/mode/shenandoahPassiveMode.cpp b/src/hotspot/share/gc/shenandoah/mode/shenandoahPassiveMode.cpp
index 39eb475a75d..9b83df5424d 100644
--- a/src/hotspot/share/gc/shenandoah/mode/shenandoahPassiveMode.cpp
+++ b/src/hotspot/share/gc/shenandoah/mode/shenandoahPassiveMode.cpp
@@ -47,7 +47,6 @@ void ShenandoahPassiveMode::initialize_flags() const {
   // Disable known barriers by default.
   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
-  SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahIUBarrier);
   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStackWatermarkBarrier);
diff --git a/src/hotspot/share/gc/shenandoah/mode/shenandoahSATBMode.cpp b/src/hotspot/share/gc/shenandoah/mode/shenandoahSATBMode.cpp
index 2a456012656..c3ea11cf71e 100644
--- a/src/hotspot/share/gc/shenandoah/mode/shenandoahSATBMode.cpp
+++ b/src/hotspot/share/gc/shenandoah/mode/shenandoahSATBMode.cpp
@@ -44,7 +44,6 @@ void ShenandoahSATBMode::initialize_flags() const {
 
   // Final configuration checks
   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
-  SHENANDOAH_CHECK_FLAG_UNSET(ShenandoahIUBarrier);
   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp b/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp
index d9b28c1bb4d..bcc370eeb31 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp
@@ -48,7 +48,6 @@ void ShenandoahArguments::initialize() {
 
   FLAG_SET_DEFAULT(ShenandoahSATBBarrier,            false);
   FLAG_SET_DEFAULT(ShenandoahLoadRefBarrier,         false);
-  FLAG_SET_DEFAULT(ShenandoahIUBarrier,              false);
   FLAG_SET_DEFAULT(ShenandoahCASBarrier,             false);
   FLAG_SET_DEFAULT(ShenandoahCloneBarrier,           false);
 
@@ -142,7 +141,6 @@ void ShenandoahArguments::initialize() {
   if (ShenandoahVerifyOptoBarriers &&
           (!FLAG_IS_DEFAULT(ShenandoahSATBBarrier)            ||
            !FLAG_IS_DEFAULT(ShenandoahLoadRefBarrier)         ||
-           !FLAG_IS_DEFAULT(ShenandoahIUBarrier)              ||
            !FLAG_IS_DEFAULT(ShenandoahCASBarrier)             ||
            !FLAG_IS_DEFAULT(ShenandoahCloneBarrier)
           )) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahAsserts.cpp b/src/hotspot/share/gc/shenandoah/shenandoahAsserts.cpp
index beb4a1d2892..5215aa749ae 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahAsserts.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahAsserts.cpp
@@ -250,6 +250,25 @@ void ShenandoahAsserts::assert_correct(void* interior_loc, oop obj, const char*
                     file, line);
     }
   }
+
+  // Do additional checks for special objects: their fields can hold metadata as well.
+  // We want to check class loading/unloading did not corrupt them.
+
+  if (java_lang_Class::is_instance(obj)) {
+    Metadata* klass = obj->metadata_field(java_lang_Class::klass_offset());
+    if (klass != nullptr && !Metaspace::contains(klass)) {
+      print_failure(_safe_all, obj, interior_loc, nullptr, "Shenandoah assert_correct failed",
+                    "Instance class mirror should point to Metaspace",
+                    file, line);
+    }
+
+    Metadata* array_klass = obj->metadata_field(java_lang_Class::array_klass_offset());
+    if (array_klass != nullptr && !Metaspace::contains(array_klass)) {
+      print_failure(_safe_all, obj, interior_loc, nullptr, "Shenandoah assert_correct failed",
+                    "Array class mirror should point to Metaspace",
+                    file, line);
+    }
+  }
 }
 
 void ShenandoahAsserts::assert_in_correct_region(void* interior_loc, oop obj, const char* file, int line) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp
index d2857daccf6..40b6d70ce45 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp
@@ -138,7 +138,7 @@ void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
 }
 
 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
-  if (_heap->has_forwarded_objects() || (ShenandoahIUBarrier && _heap->is_concurrent_mark_in_progress())) {
+  if (_heap->has_forwarded_objects()) {
     clone_barrier(src);
   }
 }
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
index beb6ae492b8..e116e0225db 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
@@ -89,7 +89,6 @@ class ShenandoahBarrierSet: public BarrierSet {
   template <DecoratorSet decorators, typename T>
   inline void satb_barrier(T* field);
   inline void satb_enqueue(oop value);
-  inline void iu_barrier(oop obj);
 
   inline void keep_alive_if_weak(DecoratorSet decorators, oop value);
 
@@ -120,7 +119,6 @@ class ShenandoahBarrierSet: public BarrierSet {
   template <class T>
   inline void arraycopy_update(T* src, size_t count);
 
-  inline void clone_marking(oop src);
   inline void clone_evacuation(oop src);
   inline void clone_update(oop src);
 
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
index bfb69c38c33..80735f453c6 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
@@ -164,12 +164,6 @@ inline void ShenandoahBarrierSet::satb_enqueue(oop value) {
   }
 }
 
-inline void ShenandoahBarrierSet::iu_barrier(oop obj) {
-  if (ShenandoahIUBarrier && obj != nullptr && _heap->is_concurrent_mark_in_progress()) {
-    enqueue(obj);
-  }
-}
-
 inline void ShenandoahBarrierSet::keep_alive_if_weak(DecoratorSet decorators, oop value) {
   assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Reference strength must be known");
   const bool on_strong_oop_ref = (decorators & ON_STRONG_OOP_REF) != 0;
@@ -189,7 +183,6 @@ inline oop ShenandoahBarrierSet::oop_load(DecoratorSet decorators, T* addr) {
 
 template <typename T>
 inline oop ShenandoahBarrierSet::oop_cmpxchg(DecoratorSet decorators, T* addr, oop compare_value, oop new_value) {
-  iu_barrier(new_value);
   oop res;
   oop expected = compare_value;
   do {
@@ -207,7 +200,6 @@ inline oop ShenandoahBarrierSet::oop_cmpxchg(DecoratorSet decorators, T* addr, o
 
 template <typename T>
 inline oop ShenandoahBarrierSet::oop_xchg(DecoratorSet decorators, T* addr, oop new_value) {
-  iu_barrier(new_value);
   oop previous = RawAccess<>::oop_atomic_xchg(addr, new_value);
   // Note: We don't need a keep-alive-barrier here. We already enqueue any loaded reference for SATB anyway,
   // because it must be the previous value.
@@ -245,7 +237,6 @@ inline void ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_st
   shenandoah_assert_marked_if(nullptr, value, !CompressedOops::is_null(value) && ShenandoahHeap::heap()->is_evacuation_in_progress());
   shenandoah_assert_not_in_cset_if(addr, value, value != nullptr && !ShenandoahHeap::heap()->cancelled_gc());
   ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
-  bs->iu_barrier(value);
   bs->satb_barrier<decorators>(addr);
   Raw::oop_store(addr, value);
 }
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetClone.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetClone.inline.hpp
index 13371f5e194..3b7bf9864de 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetClone.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetClone.inline.hpp
@@ -74,15 +74,6 @@ class ShenandoahUpdateRefsForOopClosure: public BasicOopIterateClosure {
   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 };
 
-void ShenandoahBarrierSet::clone_marking(oop obj) {
-  assert(_heap->is_concurrent_mark_in_progress(), "only during marking");
-  assert(ShenandoahIUBarrier, "only with incremental-update");
-  if (!_heap->marking_context()->allocated_after_mark_start(obj)) {
-    ShenandoahUpdateRefsForOopClosure</* has_fwd = */ false, /* evac = */ false, /* enqueue */ true> cl;
-    obj->oop_iterate(&cl);
-  }
-}
-
 void ShenandoahBarrierSet::clone_evacuation(oop obj) {
   assert(_heap->is_evacuation_in_progress(), "only during evacuation");
   if (need_bulk_update(cast_from_oop<HeapWord*>(obj))) {
@@ -105,9 +96,7 @@ void ShenandoahBarrierSet::clone_barrier(oop obj) {
   shenandoah_assert_correct(nullptr, obj);
 
   int gc_state = _heap->gc_state();
-  if ((gc_state & ShenandoahHeap::MARKING) != 0) {
-    clone_marking(obj);
-  } else if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
+  if ((gc_state & ShenandoahHeap::EVACUATION) != 0) {
     clone_evacuation(obj);
   } else {
     clone_update(obj);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
index e61dca2bdbf..657cd681f4f 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
@@ -103,11 +103,6 @@ class ShenandoahDisarmNMethodsTask : public WorkerTask {
     WorkerTask("Shenandoah Disarm NMethods"),
     _iterator(ShenandoahCodeRoots::table()) {
     assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint");
-    _iterator.nmethods_do_begin();
-  }
-
-  ~ShenandoahDisarmNMethodsTask() {
-    _iterator.nmethods_do_end();
   }
 
   virtual void work(uint worker_id) {
@@ -175,13 +170,7 @@ class ShenandoahUnlinkTask : public WorkerTask {
   ShenandoahUnlinkTask(bool unloading_occurred) :
     WorkerTask("Shenandoah Unlink NMethods"),
     _cl(unloading_occurred),
-    _iterator(ShenandoahCodeRoots::table()) {
-    _iterator.nmethods_do_begin();
-  }
-
-  ~ShenandoahUnlinkTask() {
-    _iterator.nmethods_do_end();
-  }
+    _iterator(ShenandoahCodeRoots::table()) {}
 
   virtual void work(uint worker_id) {
     _iterator.nmethods_do(&_cl);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp
index aea0af24575..ac2e732052a 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp
@@ -767,16 +767,9 @@ class ShenandoahConcurrentWeakRootsEvacUpdateTask : public WorkerTask {
     _vm_roots(phase),
     _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
     _nmethod_itr(ShenandoahCodeRoots::table()),
-    _phase(phase) {
-    if (ShenandoahHeap::heap()->unload_classes()) {
-      _nmethod_itr.nmethods_do_begin();
-    }
-  }
+    _phase(phase) {}
 
   ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
-    if (ShenandoahHeap::heap()->unload_classes()) {
-      _nmethod_itr.nmethods_do_end();
-    }
     // Notify runtime data structures of potentially dead oops
     _vm_roots.report_num_dead();
   }
@@ -878,17 +871,7 @@ class ShenandoahConcurrentRootsEvacUpdateTask : public WorkerTask {
     _phase(phase),
     _vm_roots(phase),
     _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
-    _nmethod_itr(ShenandoahCodeRoots::table()) {
-    if (!ShenandoahHeap::heap()->unload_classes()) {
-      _nmethod_itr.nmethods_do_begin();
-    }
-  }
-
-  ~ShenandoahConcurrentRootsEvacUpdateTask() {
-    if (!ShenandoahHeap::heap()->unload_classes()) {
-      _nmethod_itr.nmethods_do_end();
-    }
-  }
+    _nmethod_itr(ShenandoahCodeRoots::table()) {}
 
   void work(uint worker_id) {
     ShenandoahConcurrentWorkerSession worker_session(worker_id);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp
index fa37fcbcfd3..31157616e0e 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp
@@ -71,22 +71,14 @@ class ShenandoahConcurrentMarkingTask : public WorkerTask {
 class ShenandoahSATBAndRemarkThreadsClosure : public ThreadClosure {
 private:
   SATBMarkQueueSet& _satb_qset;
-  OopClosure* const _cl;
 
 public:
-  ShenandoahSATBAndRemarkThreadsClosure(SATBMarkQueueSet& satb_qset, OopClosure* cl) :
-    _satb_qset(satb_qset),
-    _cl(cl)  {}
+  explicit ShenandoahSATBAndRemarkThreadsClosure(SATBMarkQueueSet& satb_qset) :
+    _satb_qset(satb_qset) {}
 
-  void do_thread(Thread* thread) {
+  void do_thread(Thread* thread) override {
     // Transfer any partial buffer to the qset for completed buffer processing.
     _satb_qset.flush_queue(ShenandoahThreadLocalData::satb_mark_queue(thread));
-    if (thread->is_Java_thread()) {
-      if (_cl != nullptr) {
-        ResourceMark rm;
-        thread->oops_do(_cl, nullptr);
-      }
-    }
   }
 };
 
@@ -118,9 +110,7 @@ class ShenandoahFinalMarkingTask : public WorkerTask {
       while (satb_mq_set.apply_closure_to_completed_buffer(&cl)) {}
       assert(!heap->has_forwarded_objects(), "Not expected");
 
-      ShenandoahMarkRefsClosure<GENERATION> mark_cl(q, rp);
-      ShenandoahSATBAndRemarkThreadsClosure tc(satb_mq_set,
-                                               ShenandoahIUBarrier ? &mark_cl : nullptr);
+      ShenandoahSATBAndRemarkThreadsClosure tc(satb_mq_set);
       Threads::possibly_parallel_threads_do(true /* is_par */, &tc);
     }
     _cm->mark_loop(worker_id, _terminator, rp, GENERATION, false /*not cancellable*/,
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahController.hpp b/src/hotspot/share/gc/shenandoah/shenandoahController.hpp
index 2808f30b444..6c28ff4e969 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahController.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahController.hpp
@@ -22,8 +22,8 @@
  *
  */
 
-#ifndef LINUX_X86_64_SERVER_SLOWDEBUG_SHENANDOAHCONTROLLER_HPP
-#define LINUX_X86_64_SERVER_SLOWDEBUG_SHENANDOAHCONTROLLER_HPP
+#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLLER_HPP
+#define SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLLER_HPP
 
 #include "gc/shared/gcCause.hpp"
 #include "gc/shared/concurrentGCThread.hpp"
@@ -102,4 +102,4 @@ class ShenandoahController: public ConcurrentGCThread {
   size_t get_gc_id();
   void update_gc_id();
 };
-#endif //LINUX_X86_64_SERVER_SLOWDEBUG_SHENANDOAHCONTROLLER_HPP
+#endif // SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLLER_HPP
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
index 582c0d18d3e..b47bb109031 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
@@ -48,19 +48,19 @@ static const char* partition_name(ShenandoahFreeSetPartitionId t) {
 
 #ifndef PRODUCT
 void ShenandoahRegionPartitions::dump_bitmap() const {
-  log_info(gc)("Mutator range [" SSIZE_FORMAT ", " SSIZE_FORMAT "], Collector range [" SSIZE_FORMAT ", " SSIZE_FORMAT "]",
-               _leftmosts[int(ShenandoahFreeSetPartitionId::Mutator)],
-               _rightmosts[int(ShenandoahFreeSetPartitionId::Mutator)],
-               _leftmosts[int(ShenandoahFreeSetPartitionId::Collector)],
-               _rightmosts[int(ShenandoahFreeSetPartitionId::Collector)]);
-  log_info(gc)("Empty Mutator range [" SSIZE_FORMAT ", " SSIZE_FORMAT
-               "], Empty Collector range [" SSIZE_FORMAT ", " SSIZE_FORMAT "]",
-               _leftmosts_empty[int(ShenandoahFreeSetPartitionId::Mutator)],
-               _rightmosts_empty[int(ShenandoahFreeSetPartitionId::Mutator)],
-               _leftmosts_empty[int(ShenandoahFreeSetPartitionId::Collector)],
-               _rightmosts_empty[int(ShenandoahFreeSetPartitionId::Collector)]);
-
-  log_info(gc)("%6s: %18s %18s %18s", "index", "Mutator Bits", "Collector Bits", "NotFree Bits");
+  log_debug(gc)("Mutator range [" SSIZE_FORMAT ", " SSIZE_FORMAT "], Collector range [" SSIZE_FORMAT ", " SSIZE_FORMAT "]",
+                _leftmosts[int(ShenandoahFreeSetPartitionId::Mutator)],
+                _rightmosts[int(ShenandoahFreeSetPartitionId::Mutator)],
+                _leftmosts[int(ShenandoahFreeSetPartitionId::Collector)],
+                _rightmosts[int(ShenandoahFreeSetPartitionId::Collector)]);
+  log_debug(gc)("Empty Mutator range [" SSIZE_FORMAT ", " SSIZE_FORMAT
+                "], Empty Collector range [" SSIZE_FORMAT ", " SSIZE_FORMAT "]",
+                _leftmosts_empty[int(ShenandoahFreeSetPartitionId::Mutator)],
+                _rightmosts_empty[int(ShenandoahFreeSetPartitionId::Mutator)],
+                _leftmosts_empty[int(ShenandoahFreeSetPartitionId::Collector)],
+                _rightmosts_empty[int(ShenandoahFreeSetPartitionId::Collector)]);
+
+  log_debug(gc)("%6s: %18s %18s %18s", "index", "Mutator Bits", "Collector Bits", "NotFree Bits");
   dump_bitmap_range(0, _max-1);
 }
 
@@ -83,8 +83,8 @@ void ShenandoahRegionPartitions::dump_bitmap_row(idx_t region_idx) const {
   uintx collector_bits = _membership[int(ShenandoahFreeSetPartitionId::Collector)].bits_at(aligned_idx);
   uintx free_bits = mutator_bits | collector_bits;
   uintx notfree_bits =  ~free_bits;
-  log_info(gc)(SSIZE_FORMAT_W(6) ": " SIZE_FORMAT_X_0 " 0x" SIZE_FORMAT_X_0 " 0x" SIZE_FORMAT_X_0,
-               aligned_idx, mutator_bits, collector_bits, notfree_bits);
+  log_debug(gc)(SSIZE_FORMAT_W(6) ": " SIZE_FORMAT_X_0 " 0x" SIZE_FORMAT_X_0 " 0x" SIZE_FORMAT_X_0,
+                aligned_idx, mutator_bits, collector_bits, notfree_bits);
 }
 #endif
 
@@ -1060,8 +1060,8 @@ void ShenandoahFreeSet::move_regions_from_collector_to_mutator(size_t max_xfer_r
   }
 
   size_t collector_xfer = collector_empty_xfer + collector_not_empty_xfer;
-  log_info(gc)("At start of update refs, moving " SIZE_FORMAT "%s to Mutator free partition from Collector Reserve",
-               byte_size_in_proper_unit(collector_xfer), proper_unit_for_byte_size(collector_xfer));
+  log_info(gc, ergo)("At start of update refs, moving " SIZE_FORMAT "%s to Mutator free partition from Collector Reserve",
+                     byte_size_in_proper_unit(collector_xfer), proper_unit_for_byte_size(collector_xfer));
 }
 
 void ShenandoahFreeSet::prepare_to_rebuild(size_t &cset_regions) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
index f93ca9d6d7d..eb6de9719dc 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
@@ -66,7 +66,6 @@
 #include "gc/shenandoah/shenandoahVMOperations.hpp"
 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
-#include "gc/shenandoah/mode/shenandoahIUMode.hpp"
 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
 #if INCLUDE_JFR
@@ -446,8 +445,6 @@ void ShenandoahHeap::initialize_mode() {
   if (ShenandoahGCMode != nullptr) {
     if (strcmp(ShenandoahGCMode, "satb") == 0) {
       _gc_mode = new ShenandoahSATBMode();
-    } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
-      _gc_mode = new ShenandoahIUMode();
     } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
       _gc_mode = new ShenandoahPassiveMode();
     } else {
@@ -1693,19 +1690,20 @@ class ShenandoahParallelHeapRegionTask : public WorkerTask {
 private:
   ShenandoahHeap* const _heap;
   ShenandoahHeapRegionClosure* const _blk;
+  size_t const _stride;
 
   shenandoah_padding(0);
   volatile size_t _index;
   shenandoah_padding(1);
 
 public:
-  ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
+  ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk, size_t stride) :
           WorkerTask("Shenandoah Parallel Region Operation"),
-          _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
+          _heap(ShenandoahHeap::heap()), _blk(blk), _stride(stride), _index(0) {}
 
   void work(uint worker_id) {
     ShenandoahParallelWorkerSession worker_session(worker_id);
-    size_t stride = ShenandoahParallelRegionStride;
+    size_t stride = _stride;
 
     size_t max = _heap->num_regions();
     while (Atomic::load(&_index) < max) {
@@ -1724,8 +1722,20 @@ class ShenandoahParallelHeapRegionTask : public WorkerTask {
 
 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
   assert(blk->is_thread_safe(), "Only thread-safe closures here");
-  if (num_regions() > ShenandoahParallelRegionStride) {
-    ShenandoahParallelHeapRegionTask task(blk);
+  const uint active_workers = workers()->active_workers();
+  const size_t n_regions = num_regions();
+  size_t stride = ShenandoahParallelRegionStride;
+  if (stride == 0 && active_workers > 1) {
+    // Automatically derive the stride to balance the work between threads
+    // evenly. Do not try to split work if below the reasonable threshold.
+    constexpr size_t threshold = 4096;
+    stride = n_regions <= threshold ?
+            threshold :
+            (n_regions + active_workers - 1) / active_workers;
+  }
+
+  if (n_regions > stride && active_workers > 1) {
+    ShenandoahParallelHeapRegionTask task(blk, stride);
     workers()->run_task(&task);
   } else {
     heap_region_iterate(blk);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.hpp b/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.hpp
index 40f48bae6f5..06ea6a8e232 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.hpp
@@ -23,8 +23,8 @@
  *
  */
 
-#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
-#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
+#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
+#define SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
 
 #include "memory/memRegion.hpp"
 #include "runtime/atomic.hpp"
@@ -176,4 +176,4 @@ class ShenandoahMarkBitMap {
 
 };
 
-#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
+#endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_HPP
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.inline.hpp
index 62c0eaea139..bf9261f47ac 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.inline.hpp
@@ -23,8 +23,8 @@
  *
  */
 
-#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
-#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
+#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
+#define SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
 
 #include "gc/shenandoah/shenandoahMarkBitMap.hpp"
 
@@ -205,4 +205,4 @@ inline void ShenandoahMarkBitMap::clear_range_of_words(idx_t beg, idx_t end) {
 }
 
 
-#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
+#endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARKBITMAP_INLINE_HPP
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp b/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp
index 54efd658eaf..5eb0b277b5e 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp
@@ -31,6 +31,7 @@
 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/continuation.hpp"
+#include "runtime/safepointVerifiers.hpp"
 
 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>& oops, bool non_immediate_oops) :
   _nm(nm), _oops(nullptr), _oops_count(0), _unregistered(false), _lock(), _ic_lock() {
@@ -475,21 +476,40 @@ void ShenandoahNMethodTableSnapshot::concurrent_nmethods_do(NMethodClosure* cl)
 }
 
 ShenandoahConcurrentNMethodIterator::ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table) :
-  _table(table), _table_snapshot(nullptr) {
-}
-
-void ShenandoahConcurrentNMethodIterator::nmethods_do_begin() {
-  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-  _table_snapshot = _table->snapshot_for_iteration();
-}
+  _table(table),
+  _table_snapshot(nullptr),
+  _started_workers(0),
+  _finished_workers(0) {}
 
 void ShenandoahConcurrentNMethodIterator::nmethods_do(NMethodClosure* cl) {
-  assert(_table_snapshot != nullptr, "Must first call nmethod_do_begin()");
-  _table_snapshot->concurrent_nmethods_do(cl);
-}
+  // Cannot safepoint when iteration is running, because this can cause deadlocks
+  // with other threads waiting on iteration to be over.
+  NoSafepointVerifier nsv;
 
-void ShenandoahConcurrentNMethodIterator::nmethods_do_end() {
-  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-  _table->finish_iteration(_table_snapshot);
-  CodeCache_lock->notify_all();
+  MutexLocker ml(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+
+  if (_finished_workers > 0) {
+    // Some threads have already finished. We are now in rampdown: we are now
+    // waiting for all currently recorded workers to finish. No new workers
+    // should start.
+    return;
+  }
+
+  // Record a new worker and initialize the snapshot if it is a first visitor.
+  if (_started_workers++ == 0) {
+    _table_snapshot = _table->snapshot_for_iteration();
+  }
+
+  // All set, relinquish the lock and go concurrent.
+  {
+    MutexUnlocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+    _table_snapshot->concurrent_nmethods_do(cl);
+  }
+
+  // Record completion. Last worker shuts down the iterator and notifies any waiters.
+  uint count = ++_finished_workers;
+  if (count == _started_workers) {
+    _table->finish_iteration(_table_snapshot);
+    CodeCache_lock->notify_all();
+  }
 }
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahNMethod.hpp b/src/hotspot/share/gc/shenandoah/shenandoahNMethod.hpp
index 4e05d254db3..c1595396500 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahNMethod.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahNMethod.hpp
@@ -181,13 +181,13 @@ class ShenandoahConcurrentNMethodIterator {
 private:
   ShenandoahNMethodTable*         const _table;
   ShenandoahNMethodTableSnapshot*       _table_snapshot;
+  uint                                  _started_workers;
+  uint                                  _finished_workers;
 
 public:
   ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table);
 
-  void nmethods_do_begin();
   void nmethods_do(NMethodClosure* cl);
-  void nmethods_do_end();
 };
 
 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHNMETHOD_HPP
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.hpp b/src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.hpp
index c4ecf8d359a..fa523551790 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.hpp
@@ -23,8 +23,8 @@
  *
  */
 
-#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
-#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
+#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
+#define SHARE_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
 
 #include "gc/shared/referenceDiscoverer.hpp"
 #include "gc/shared/referencePolicy.hpp"
@@ -188,4 +188,4 @@ class ShenandoahReferenceProcessor : public ReferenceDiscoverer {
   void abandon_partial_discovery();
 };
 
-#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
+#endif // SHARE_GC_SHENANDOAH_SHENANDOAHREFERENCEPROCESSOR_HPP
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp b/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp
index f67cafdb8fe..694736cea42 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp
@@ -212,6 +212,21 @@ class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
       fwd_reg = obj_reg;
     }
 
+    // Do additional checks for special objects: their fields can hold metadata as well.
+    // We want to check class loading/unloading did not corrupt them.
+
+    if (java_lang_Class::is_instance(obj)) {
+      Metadata* klass = obj->metadata_field(java_lang_Class::klass_offset());
+      check(ShenandoahAsserts::_safe_oop, obj,
+            klass == nullptr || Metaspace::contains(klass),
+            "Instance class mirror should point to Metaspace");
+
+      Metadata* array_klass = obj->metadata_field(java_lang_Class::array_klass_offset());
+      check(ShenandoahAsserts::_safe_oop, obj,
+            array_klass == nullptr || Metaspace::contains(array_klass),
+            "Array class mirror should point to Metaspace");
+    }
+
     // ------------ obj and fwd are safe at this point --------------
 
     switch (_options._verify_marked) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
index b8baf6b3ebf..87702afe98e 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
@@ -318,9 +318,10 @@
           "checking for cancellation, yielding, etc. Larger values improve "\
           "marking performance at expense of responsiveness.")              \
                                                                             \
-  product(uintx, ShenandoahParallelRegionStride, 1024, EXPERIMENTAL,        \
+  product(uintx, ShenandoahParallelRegionStride, 0, EXPERIMENTAL,           \
           "How many regions to process at once during parallel region "     \
-          "iteration. Affects heaps with lots of regions.")                 \
+          "iteration. Affects heaps with lots of regions. "                 \
+          "Set to 0 to let Shenandoah to decide the best value.")           \
                                                                             \
   product(size_t, ShenandoahSATBBufferSize, 1 * K, EXPERIMENTAL,            \
           "Number of entries in an SATB log buffer.")                       \
@@ -333,9 +334,6 @@
   product(bool, ShenandoahSATBBarrier, true, DIAGNOSTIC,                    \
           "Turn on/off SATB barriers in Shenandoah")                        \
                                                                             \
-  product(bool, ShenandoahIUBarrier, false, DIAGNOSTIC,                     \
-          "Turn on/off I-U barriers barriers in Shenandoah")                \
-                                                                            \
   product(bool, ShenandoahCASBarrier, true, DIAGNOSTIC,                     \
           "Turn on/off CAS barriers in Shenandoah")                         \
                                                                             \
diff --git a/src/hotspot/share/include/jvm.h b/src/hotspot/share/include/jvm.h
index a18e9bffc85..6082af55487 100644
--- a/src/hotspot/share/include/jvm.h
+++ b/src/hotspot/share/include/jvm.h
@@ -295,9 +295,6 @@ JVM_HoldsLock(JNIEnv *env, jclass threadClass, jobject obj);
 JNIEXPORT jobject JNICALL
 JVM_GetStackTrace(JNIEnv *env, jobject thread);
 
-JNIEXPORT void JNICALL
-JVM_DumpAllStacks(JNIEnv *env, jclass unused);
-
 JNIEXPORT jobjectArray JNICALL
 JVM_GetAllThreads(JNIEnv *env, jclass dummy);
 
diff --git a/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp b/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
index c62257bd23b..79bc97f53ac 100644
--- a/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
+++ b/src/hotspot/share/jvmci/jvmciCodeInstaller.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -664,7 +664,7 @@ JVMCI::CodeInstallResult CodeInstaller::install_runtime_stub(CodeBlob*& cb,
   GrowableArray<RuntimeStub*> *stubs_to_free = nullptr;
 #ifdef ASSERT
   const char* val = Arguments::PropertyList_get_value(Arguments::system_properties(), "test.jvmci.forceRuntimeStubAllocFail");
-  if (val != nullptr && strstr(name , val) != 0) {
+  if (val != nullptr && strstr(name , val) != nullptr) {
     stubs_to_free = new GrowableArray<RuntimeStub*>();
     JVMCI_event_1("forcing allocation of %s in code cache to fail", name);
   }
diff --git a/src/hotspot/share/jvmci/jvmciCompilerToVM.cpp b/src/hotspot/share/jvmci/jvmciCompilerToVM.cpp
index 5583ad8a6f5..5a9b18fc4d3 100644
--- a/src/hotspot/share/jvmci/jvmciCompilerToVM.cpp
+++ b/src/hotspot/share/jvmci/jvmciCompilerToVM.cpp
@@ -94,6 +94,12 @@ static void requireInHotSpot(const char* caller, JVMCI_TRAPS) {
   }
 }
 
+static void requireNotInHotSpot(const char* caller, JVMCI_TRAPS) {
+    if (JVMCIENV->is_hotspot()) {
+        JVMCI_THROW_MSG(IllegalStateException, err_msg("Cannot call %s from HotSpot", caller));
+    }
+}
+
 class JVMCITraceMark : public StackObj {
   const char* _msg;
  public:
@@ -418,7 +424,7 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaMethod, (JNIEnv* env, jobject, jobject
 
 C2V_VMENTRY_NULL(jobject, getConstantPool, (JNIEnv* env, jobject, ARGUMENT_PAIR(klass_or_method), jboolean is_klass))
   ConstantPool* cp = nullptr;
-  if (UNPACK_PAIR(address, klass_or_method) == 0) {
+  if (UNPACK_PAIR(address, klass_or_method) == nullptr) {
     JVMCI_THROW_NULL(NullPointerException);
   }
   if (!is_klass) {
@@ -702,6 +708,17 @@ C2V_VMENTRY_NULL(jobject, lookupJClass, (JNIEnv* env, jobject, jlong jclass_valu
     return JVMCIENV->get_jobject(result);
 C2V_END
 
+C2V_VMENTRY_0(jlong, getJObjectValue, (JNIEnv* env, jobject, jobject constant_jobject))
+    requireNotInHotSpot("getJObjectValue", JVMCI_CHECK_0);
+    if (!THREAD->has_last_Java_frame()) {
+        JVMCI_THROW_MSG_0(IllegalStateException, err_msg("Cannot call getJObjectValue without Java frame anchor"));
+    }
+    JVMCIObject constant = JVMCIENV->wrap(constant_jobject);
+    Handle constant_value = JVMCIENV->asConstant(constant, JVMCI_CHECK_0);
+    jobject jni_handle = JNIHandles::make_local(THREAD, constant_value());
+    return reinterpret_cast<jlong>(jni_handle);
+C2V_END
+
 C2V_VMENTRY_NULL(jobject, getUncachedStringInPool, (JNIEnv* env, jobject, ARGUMENT_PAIR(cp), jint index))
   constantPoolHandle cp(THREAD, UNPACK_PAIR(ConstantPool, cp));
   constantTag tag = cp->tag_at(index);
@@ -1081,7 +1098,7 @@ C2V_END
 
 C2V_VMENTRY_0(jlong, getMaxCallTargetOffset, (JNIEnv* env, jobject, jlong addr))
   address target_addr = (address) addr;
-  if (target_addr != 0x0) {
+  if (target_addr != nullptr) {
     int64_t off_low = (int64_t)target_addr - ((int64_t)CodeCache::low_bound() + sizeof(int));
     int64_t off_high = (int64_t)target_addr - ((int64_t)CodeCache::high_bound() + sizeof(int));
     return MAX2(ABS(off_low), ABS(off_high));
@@ -3254,6 +3271,7 @@ JNINativeMethod CompilerToVM::methods[] = {
   {CC "shouldInlineMethod",                           CC "(" HS_METHOD2 ")Z",                                                               FN_PTR(shouldInlineMethod)},
   {CC "lookupType",                                   CC "(" STRING HS_KLASS2 "IZ)" HS_RESOLVED_TYPE,                                       FN_PTR(lookupType)},
   {CC "lookupJClass",                                 CC "(J)" HS_RESOLVED_TYPE,                                                            FN_PTR(lookupJClass)},
+  {CC "getJObjectValue",                              CC "(" OBJECTCONSTANT ")J",                                                           FN_PTR(getJObjectValue)},
   {CC "getArrayType",                                 CC "(C" HS_KLASS2 ")" HS_KLASS,                                                       FN_PTR(getArrayType)},
   {CC "lookupClass",                                  CC "(" CLASS ")" HS_RESOLVED_TYPE,                                                    FN_PTR(lookupClass)},
   {CC "lookupNameInPool",                             CC "(" HS_CONSTANT_POOL2 "II)" STRING,                                                FN_PTR(lookupNameInPool)},
diff --git a/src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp b/src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp
index f1028b4b2bb..2116133e56e 100644
--- a/src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp
+++ b/src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp
@@ -240,7 +240,7 @@ void CompilerToVM::Data::initialize(JVMCI_TRAPS) {
     cardtable_shift = CardTable::card_shift();
   } else {
     // No card mark barriers
-    cardtable_start_address = 0;
+    cardtable_start_address = nullptr;
     cardtable_shift = 0;
   }
 
diff --git a/src/hotspot/share/jvmci/jvmciRuntime.cpp b/src/hotspot/share/jvmci/jvmciRuntime.cpp
index 371a6540898..ad0430787aa 100644
--- a/src/hotspot/share/jvmci/jvmciRuntime.cpp
+++ b/src/hotspot/share/jvmci/jvmciRuntime.cpp
@@ -628,7 +628,7 @@ JRT_LEAF(oopDesc*, JVMCIRuntime::load_and_clear_exception(JavaThread* thread))
   oop exception = thread->exception_oop();
   assert(exception != nullptr, "npe");
   thread->set_exception_oop(nullptr);
-  thread->set_exception_pc(0);
+  thread->set_exception_pc(nullptr);
   return exception;
 JRT_END
 
diff --git a/src/hotspot/share/libadt/vectset.cpp b/src/hotspot/share/libadt/vectset.cpp
index 9c711a7021b..b0d5d100400 100644
--- a/src/hotspot/share/libadt/vectset.cpp
+++ b/src/hotspot/share/libadt/vectset.cpp
@@ -48,6 +48,10 @@ void VectorSet::init(Arena* arena) {
 
 // Expand the existing set to a bigger size
 void VectorSet::grow(uint new_word_capacity) {
+  _nesting.check(_set_arena); // Check if a potential reallocation in the arena is safe
+  if (new_word_capacity < _size) {
+    return; // No need to grow
+  }
   assert(new_word_capacity < (1U << 30), "");
   uint x = next_power_of_2(new_word_capacity);
   if (x > _data_size) {
diff --git a/src/hotspot/share/libadt/vectset.hpp b/src/hotspot/share/libadt/vectset.hpp
index d55837c3b2b..eafa60db1fe 100644
--- a/src/hotspot/share/libadt/vectset.hpp
+++ b/src/hotspot/share/libadt/vectset.hpp
@@ -42,10 +42,11 @@ class VectorSet : public AnyObj {
 
   // Used 32-bit words
   uint       _size;
-  uint32_t*  _data;
   // Allocated words
   uint       _data_size;
+  uint32_t*  _data;
   Arena*     _set_arena;
+  ReallocMark _nesting; // Safety checks for arena reallocation
 
   void init(Arena* arena);
   // Grow vector to required word capacity
@@ -77,10 +78,7 @@ class VectorSet : public AnyObj {
   //
   bool test_set(uint elem) {
     uint32_t word = elem >> word_bits;
-    if (word >= _size) {
-      // Then grow
-      grow(word);
-    }
+    grow(word);
     uint32_t mask = 1U << (elem & bit_mask);
     uint32_t data = _data[word];
     _data[word] = data | mask;
@@ -109,9 +107,7 @@ class VectorSet : public AnyObj {
   // Fast inlined set
   void set(uint elem) {
     uint32_t word = elem >> word_bits;
-    if (word >= _size) {
-      grow(word);
-    }
+    grow(word);
     uint32_t mask = 1U << (elem & bit_mask);
     _data[word] |= mask;
   }
diff --git a/src/hotspot/share/logging/logConfiguration.cpp b/src/hotspot/share/logging/logConfiguration.cpp
index 3a54d1f4e63..87b195f4fbf 100644
--- a/src/hotspot/share/logging/logConfiguration.cpp
+++ b/src/hotspot/share/logging/logConfiguration.cpp
@@ -370,7 +370,7 @@ bool LogConfiguration::parse_command_line_arguments(const char* opts) {
 
   // Split the option string to its colon separated components.
   char* str = copy;
-  char* substrings[4] = {0};
+  char* substrings[4] = {};
   for (int i = 0 ; i < 4; i++) {
     substrings[i] = str;
 
diff --git a/src/hotspot/share/memory/allocation.cpp b/src/hotspot/share/memory/allocation.cpp
index 0f05bdda461..0f2ff7840b8 100644
--- a/src/hotspot/share/memory/allocation.cpp
+++ b/src/hotspot/share/memory/allocation.cpp
@@ -237,9 +237,10 @@ ReallocMark::ReallocMark() {
 #endif
 }
 
-void ReallocMark::check() {
+void ReallocMark::check(Arena* arena) {
 #ifdef ASSERT
-  if (_nesting != Thread::current()->resource_area()->nesting()) {
+  if ((arena == nullptr || arena == Thread::current()->resource_area()) &&
+      _nesting != Thread::current()->resource_area()->nesting()) {
     fatal("allocation bug: array could grow within nested ResourceMark");
   }
 #endif
diff --git a/src/hotspot/share/memory/allocation.hpp b/src/hotspot/share/memory/allocation.hpp
index 495ca66d867..da5f7b19830 100644
--- a/src/hotspot/share/memory/allocation.hpp
+++ b/src/hotspot/share/memory/allocation.hpp
@@ -556,8 +556,8 @@ class ReallocMark: public StackObj {
   NOT_PRODUCT(int _nesting;)
 
 public:
-  ReallocMark()   PRODUCT_RETURN;
-  void check()    PRODUCT_RETURN;
+  ReallocMark() PRODUCT_RETURN;
+  void check(Arena* arena = nullptr) PRODUCT_RETURN;
 };
 
 // Uses mmapped memory for all allocations. All allocations are initially
diff --git a/src/hotspot/share/memory/arena.cpp b/src/hotspot/share/memory/arena.cpp
index 0399c6922e3..435a8cfdd58 100644
--- a/src/hotspot/share/memory/arena.cpp
+++ b/src/hotspot/share/memory/arena.cpp
@@ -44,6 +44,19 @@ STATIC_ASSERT(is_aligned((int)Chunk::init_size, ARENA_AMALLOC_ALIGNMENT));
 STATIC_ASSERT(is_aligned((int)Chunk::medium_size, ARENA_AMALLOC_ALIGNMENT));
 STATIC_ASSERT(is_aligned((int)Chunk::size, ARENA_AMALLOC_ALIGNMENT));
 
+
+const char* Arena::tag_name[] = {
+#define ARENA_TAG_STRING(name, str, desc) XSTR(name),
+  DO_ARENA_TAG(ARENA_TAG_STRING)
+#undef ARENA_TAG_STRING
+};
+
+const char* Arena::tag_desc[] = {
+#define ARENA_TAG_DESC(name, str, desc) XSTR(desc),
+  DO_ARENA_TAG(ARENA_TAG_DESC)
+#undef ARENA_TAG_DESC
+};
+
 // MT-safe pool of same-sized chunks to reduce malloc/free thrashing
 // NB: not using Mutex because pools are used before Threads are initialized
 class ChunkPool {
diff --git a/src/hotspot/share/memory/arena.hpp b/src/hotspot/share/memory/arena.hpp
index 1ca8a787825..1f3c5eb4e8b 100644
--- a/src/hotspot/share/memory/arena.hpp
+++ b/src/hotspot/share/memory/arena.hpp
@@ -83,17 +83,29 @@ class Chunk {
   bool contains(char* p) const  { return bottom() <= p && p <= top(); }
 };
 
+#define DO_ARENA_TAG(FN) \
+  FN(other, Others, Other arenas) \
+  FN(ra, RA, Resource areas) \
+  FN(ha, HA, Handle area) \
+  FN(node, NA, Node arena) \
+
 // Fast allocation of memory
 class Arena : public CHeapObjBase {
 public:
-
-  enum class Tag : uint8_t {
-    tag_other = 0,
-    tag_ra,   // resource area
-    tag_ha,   // handle area
-    tag_node  // C2 Node arena
+  enum class Tag: uint8_t {
+#define ARENA_TAG_ENUM(name, str, desc) tag_##name,
+    DO_ARENA_TAG(ARENA_TAG_ENUM)
+#undef ARENA_TAG_ENUM
+    tag_count
   };
 
+  constexpr static int tag_count() {
+    return static_cast<int>(Tag::tag_count);
+  }
+
+  static const char* tag_name[static_cast<int>(Arena::Tag::tag_count)];
+  static const char* tag_desc[static_cast<int>(Arena::Tag::tag_count)];
+
 private:
   const MEMFLAGS _flags;        // Memory tracking flags
   const Tag _tag;
diff --git a/src/hotspot/share/memory/metaspace/metachunk.cpp b/src/hotspot/share/memory/metaspace/metachunk.cpp
index 3d67aac8016..0bf7e98f130 100644
--- a/src/hotspot/share/memory/metaspace/metachunk.cpp
+++ b/src/hotspot/share/memory/metaspace/metachunk.cpp
@@ -253,7 +253,7 @@ void Metachunk::verify_neighborhood() const {
   }
 }
 
-volatile MetaWord dummy = 0;
+volatile MetaWord dummy = nullptr;
 
 void Metachunk::verify() const {
   // Note. This should be called under CLD lock protection.
diff --git a/src/hotspot/share/memory/metaspace/rootChunkArea.cpp b/src/hotspot/share/memory/metaspace/rootChunkArea.cpp
index ee3af35a5b8..24377ec25ad 100644
--- a/src/hotspot/share/memory/metaspace/rootChunkArea.cpp
+++ b/src/hotspot/share/memory/metaspace/rootChunkArea.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, 2022 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -59,7 +59,7 @@ RootChunkArea::~RootChunkArea() {
 // root chunk header. It will be partly initialized.
 // Note: this just allocates a memory-less header; memory itself is allocated inside VirtualSpaceNode.
 Metachunk* RootChunkArea::alloc_root_chunk_header(VirtualSpaceNode* node) {
-  assert(_first_chunk == 0, "already have a root");
+  assert(_first_chunk == nullptr, "already have a root");
   Metachunk* c = ChunkHeaderPool::pool()->allocate_chunk_header();
   c->initialize(node, const_cast<MetaWord*>(_base), chunklevel::ROOT_CHUNK_LEVEL);
   _first_chunk = c;
diff --git a/src/hotspot/share/memory/virtualspace.cpp b/src/hotspot/share/memory/virtualspace.cpp
index 7df35bbeec8..c27e607353a 100644
--- a/src/hotspot/share/memory/virtualspace.cpp
+++ b/src/hotspot/share/memory/virtualspace.cpp
@@ -159,7 +159,7 @@ static char* reserve_memory(char* requested_address, const size_t size,
   // If the memory was requested at a particular address, use
   // os::attempt_reserve_memory_at() to avoid mapping over something
   // important.  If the reservation fails, return null.
-  if (requested_address != 0) {
+  if (requested_address != nullptr) {
     assert(is_aligned(requested_address, alignment),
            "Requested address " PTR_FORMAT " must be aligned to " SIZE_FORMAT,
            p2i(requested_address), alignment);
diff --git a/src/hotspot/share/oops/constantPool.cpp b/src/hotspot/share/oops/constantPool.cpp
index 35a1d95b6e6..1c295e10b21 100644
--- a/src/hotspot/share/oops/constantPool.cpp
+++ b/src/hotspot/share/oops/constantPool.cpp
@@ -2065,7 +2065,7 @@ static void print_cpool_bytes(jint cnt, u1 *bytes) {
     size  += ent_size;
   }
   printf("Cpool size: %d\n", size);
-  fflush(0);
+  fflush(nullptr);
   return;
 } /* end print_cpool_bytes */
 
diff --git a/src/hotspot/share/oops/instanceKlass.cpp b/src/hotspot/share/oops/instanceKlass.cpp
index 930f8cf1771..650279db1be 100644
--- a/src/hotspot/share/oops/instanceKlass.cpp
+++ b/src/hotspot/share/oops/instanceKlass.cpp
@@ -2779,9 +2779,9 @@ void InstanceKlass::release_C_heap_structures(bool release_sub_metadata) {
 
 #if INCLUDE_JVMTI
   // Deallocate breakpoint records
-  if (breakpoints() != 0x0) {
+  if (breakpoints() != nullptr) {
     methods_do(clear_all_breakpoints);
-    assert(breakpoints() == 0x0, "should have cleared breakpoints");
+    assert(breakpoints() == nullptr, "should have cleared breakpoints");
   }
 
   // deallocate the cached class file
diff --git a/src/hotspot/share/oops/method.cpp b/src/hotspot/share/oops/method.cpp
index e5ba0d61031..f4dcd4f1493 100644
--- a/src/hotspot/share/oops/method.cpp
+++ b/src/hotspot/share/oops/method.cpp
@@ -322,7 +322,7 @@ void Method::mask_for(const methodHandle& this_mh, int bci, InterpreterOopMap* m
 }
 
 int Method::bci_from(address bcp) const {
-  if (is_native() && bcp == 0) {
+  if (is_native() && bcp == nullptr) {
     return 0;
   }
   // Do not have a ResourceMark here because AsyncGetCallTrace stack walking code
@@ -345,7 +345,7 @@ int Method::validate_bci(int bci) const {
 int Method::validate_bci_from_bcp(address bcp) const {
   // keep bci as -1 if not a valid bci
   int bci = -1;
-  if (bcp == 0 || bcp == code_base()) {
+  if (bcp == nullptr || bcp == code_base()) {
     // code_size() may return 0 and we allow 0 here
     // the method may be native
     bci = 0;
diff --git a/src/hotspot/share/oops/stackChunkOop.cpp b/src/hotspot/share/oops/stackChunkOop.cpp
index 8d230b334c8..344fef15308 100644
--- a/src/hotspot/share/oops/stackChunkOop.cpp
+++ b/src/hotspot/share/oops/stackChunkOop.cpp
@@ -125,7 +125,7 @@ static int num_java_frames(const StackChunkFrameStream<ChunkFrames::Mixed>& f) {
 int stackChunkOopDesc::num_java_frames() const {
   int n = 0;
   for (StackChunkFrameStream<ChunkFrames::Mixed> f(const_cast<stackChunkOopDesc*>(this)); !f.is_done();
-       f.next(SmallRegisterMap::instance)) {
+       f.next(SmallRegisterMap::instance())) {
     if (!f.is_stub()) {
       n += ::num_java_frames(f);
     }
diff --git a/src/hotspot/share/oops/stackChunkOop.inline.hpp b/src/hotspot/share/oops/stackChunkOop.inline.hpp
index 54f1423fd1c..a54b8159e7e 100644
--- a/src/hotspot/share/oops/stackChunkOop.inline.hpp
+++ b/src/hotspot/share/oops/stackChunkOop.inline.hpp
@@ -201,7 +201,7 @@ inline void stackChunkOopDesc::iterate_stack(StackChunkFrameClosureType* closure
 
 template <ChunkFrames frame_kind, class StackChunkFrameClosureType>
 inline void stackChunkOopDesc::iterate_stack(StackChunkFrameClosureType* closure) {
-  const SmallRegisterMap* map = SmallRegisterMap::instance;
+  const SmallRegisterMap* map = SmallRegisterMap::instance();
   assert(!map->in_cont(), "");
 
   StackChunkFrameStream<frame_kind> f(this);
diff --git a/src/hotspot/share/opto/block.cpp b/src/hotspot/share/opto/block.cpp
index 78774ff2fd1..1af085cd128 100644
--- a/src/hotspot/share/opto/block.cpp
+++ b/src/hotspot/share/opto/block.cpp
@@ -39,7 +39,10 @@
 #include "utilities/powerOfTwo.hpp"
 
 void Block_Array::grow( uint i ) {
-  assert(i >= Max(), "must be an overflow");
+  _nesting.check(_arena); // Check if a potential reallocation in the arena is safe
+  if (i < Max()) {
+    return; // No need to grow
+  }
   debug_only(_limit = i+1);
   if( i < _size )  return;
   if( !_size ) {
@@ -374,6 +377,7 @@ void Block::dump(const PhaseCFG* cfg) const {
 PhaseCFG::PhaseCFG(Arena* arena, RootNode* root, Matcher& matcher)
 : Phase(CFG)
 , _root(root)
+, _blocks(arena)
 , _block_arena(arena)
 , _regalloc(nullptr)
 , _scheduling_for_pressure(false)
@@ -1417,7 +1421,7 @@ UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_A
 }
 
 void UnionFind::extend( uint from_idx, uint to_idx ) {
-  _nesting.check();
+  _nesting.check(); // Check if a potential reallocation in the resource arena is safe
   if( from_idx >= _max ) {
     uint size = 16;
     while( size <= from_idx ) size <<=1;
diff --git a/src/hotspot/share/opto/block.hpp b/src/hotspot/share/opto/block.hpp
index e48b50b06ae..231c0994903 100644
--- a/src/hotspot/share/opto/block.hpp
+++ b/src/hotspot/share/opto/block.hpp
@@ -51,6 +51,7 @@ class Block_Array : public ArenaObj {
   uint _size;                   // allocated size, as opposed to formal limit
   debug_only(uint _limit;)      // limit to formal domain
   Arena *_arena;                // Arena to allocate in
+  ReallocMark _nesting;         // Safety checks for arena reallocation
 protected:
   Block **_blocks;
   void grow( uint i );          // Grow array node to fit
@@ -68,7 +69,7 @@ class Block_Array : public ArenaObj {
   Block *operator[] ( uint i ) const // Lookup, or assert for not mapped
   { assert( i < Max(), "oob" ); return _blocks[i]; }
   // Extend the mapping: index i maps to Block *n.
-  void map( uint i, Block *n ) { if( i>=Max() ) grow(i); _blocks[i] = n; }
+  void map( uint i, Block *n ) { grow(i); _blocks[i] = n; }
   uint Max() const { debug_only(return _limit); return _size; }
 };
 
@@ -77,7 +78,9 @@ class Block_List : public Block_Array {
   friend class VMStructs;
 public:
   uint _cnt;
-  Block_List() : Block_Array(Thread::current()->resource_area()), _cnt(0) {}
+  Block_List() : Block_List(Thread::current()->resource_area()) { }
+  Block_List(Arena* a) : Block_Array(a), _cnt(0) { }
+
   void push( Block *b ) {  map(_cnt++,b); }
   Block *pop() { return _blocks[--_cnt]; }
   Block *rpop() { Block *b = _blocks[0]; _blocks[0]=_blocks[--_cnt]; return b;}
@@ -655,7 +658,7 @@ class PhaseCFG : public Phase {
 class UnionFind : public ResourceObj {
   uint _cnt, _max;
   uint* _indices;
-  ReallocMark _nesting;  // assertion check for reallocations
+  ReallocMark _nesting; // Safety checks for arena reallocation
 public:
   UnionFind( uint max );
   void reset( uint max );  // Reset to identity map for [0..max]
diff --git a/src/hotspot/share/opto/callnode.hpp b/src/hotspot/share/opto/callnode.hpp
index 818640a6f65..120bb112ec5 100644
--- a/src/hotspot/share/opto/callnode.hpp
+++ b/src/hotspot/share/opto/callnode.hpp
@@ -754,18 +754,18 @@ class CallJavaNode : public CallNode {
   virtual bool cmp( const Node &n ) const;
   virtual uint size_of() const; // Size is bigger
 
+  ciMethod* _method;               // Method being direct called
   bool    _optimized_virtual;
   bool    _method_handle_invoke;
   bool    _override_symbolic_info; // Override symbolic call site info from bytecode
-  ciMethod* _method;               // Method being direct called
   bool    _arg_escape;             // ArgEscape in parameter list
 public:
   CallJavaNode(const TypeFunc* tf , address addr, ciMethod* method)
     : CallNode(tf, addr, TypePtr::BOTTOM),
+      _method(method),
       _optimized_virtual(false),
       _method_handle_invoke(false),
       _override_symbolic_info(false),
-      _method(method),
       _arg_escape(false)
   {
     init_class_id(Class_CallJava);
diff --git a/src/hotspot/share/opto/castnode.hpp b/src/hotspot/share/opto/castnode.hpp
index 3e20a92e848..87989235c67 100644
--- a/src/hotspot/share/opto/castnode.hpp
+++ b/src/hotspot/share/opto/castnode.hpp
@@ -101,12 +101,9 @@ class CastIINode: public ConstraintCastNode {
   virtual uint size_of() const;
 
   public:
-  CastIINode(Node* n, const Type* t, DependencyType dependency = RegularDependency, bool range_check_dependency = false, const TypeTuple* types = nullptr)
-    : ConstraintCastNode(nullptr, n, t, dependency, types), _range_check_dependency(range_check_dependency) {
-    init_class_id(Class_CastII);
-  }
   CastIINode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, bool range_check_dependency = false, const TypeTuple* types = nullptr)
     : ConstraintCastNode(ctrl, n, t, dependency, types), _range_check_dependency(range_check_dependency) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CastII);
   }
   virtual int Opcode() const;
@@ -134,6 +131,7 @@ class CastLLNode: public ConstraintCastNode {
 public:
   CastLLNode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, const TypeTuple* types = nullptr)
           : ConstraintCastNode(ctrl, n, t, dependency, types) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CastLL);
   }
 
@@ -147,6 +145,7 @@ class CastFFNode: public ConstraintCastNode {
 public:
   CastFFNode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, const TypeTuple* types = nullptr)
           : ConstraintCastNode(ctrl, n, t, dependency, types) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CastFF);
   }
   virtual int Opcode() const;
@@ -157,6 +156,7 @@ class CastDDNode: public ConstraintCastNode {
 public:
   CastDDNode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, const TypeTuple* types = nullptr)
           : ConstraintCastNode(ctrl, n, t, dependency, types) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CastDD);
   }
   virtual int Opcode() const;
@@ -167,6 +167,7 @@ class CastVVNode: public ConstraintCastNode {
 public:
   CastVVNode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, const TypeTuple* types = nullptr)
           : ConstraintCastNode(ctrl, n, t, dependency, types) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CastVV);
   }
   virtual int Opcode() const;
@@ -192,6 +193,7 @@ class CheckCastPPNode: public ConstraintCastNode {
   public:
   CheckCastPPNode(Node* ctrl, Node* n, const Type* t, DependencyType dependency = RegularDependency, const TypeTuple* types = nullptr)
     : ConstraintCastNode(ctrl, n, t, dependency, types) {
+    assert(ctrl != nullptr, "control must be set");
     init_class_id(Class_CheckCastPP);
   }
 
diff --git a/src/hotspot/share/opto/classes.hpp b/src/hotspot/share/opto/classes.hpp
index 7908f21de10..dc613776873 100644
--- a/src/hotspot/share/opto/classes.hpp
+++ b/src/hotspot/share/opto/classes.hpp
@@ -324,7 +324,6 @@ shmacro(ShenandoahCompareAndSwapN)
 shmacro(ShenandoahCompareAndSwapP)
 shmacro(ShenandoahWeakCompareAndSwapN)
 shmacro(ShenandoahWeakCompareAndSwapP)
-shmacro(ShenandoahIUBarrier)
 shmacro(ShenandoahLoadReferenceBarrier)
 macro(SCMemProj)
 macro(CopySignD)
diff --git a/src/hotspot/share/opto/domgraph.cpp b/src/hotspot/share/opto/domgraph.cpp
index 46cf3316af5..363005d1181 100644
--- a/src/hotspot/share/opto/domgraph.cpp
+++ b/src/hotspot/share/opto/domgraph.cpp
@@ -61,9 +61,6 @@ struct Tarjan {
 // Compute the dominator tree of the CFG.  The CFG must already have been
 // constructed.  This is the Lengauer & Tarjan O(E-alpha(E,V)) algorithm.
 void PhaseCFG::build_dominator_tree() {
-  // Pre-grow the blocks array, prior to the ResourceMark kicking in
-  _blocks.map(number_of_blocks(), nullptr);
-
   ResourceMark rm;
   // Setup mappings from my Graph to Tarjan's stuff and back
   // Note: Tarjan uses 1-based arrays
diff --git a/src/hotspot/share/opto/escape.cpp b/src/hotspot/share/opto/escape.cpp
index 2ca722148b6..eb6887f11ba 100644
--- a/src/hotspot/share/opto/escape.cpp
+++ b/src/hotspot/share/opto/escape.cpp
@@ -3879,7 +3879,7 @@ PhiNode *ConnectionGraph::create_split_phi(PhiNode *orig_phi, int alias_idx, Gro
 // Return a new version of Memory Phi "orig_phi" with the inputs having the
 // specified alias index.
 //
-PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist) {
+PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *> &orig_phi_worklist, uint rec_depth) {
   assert(alias_idx != Compile::AliasIdxBot, "can't split out bottom memory");
   Compile *C = _compile;
   PhaseGVN* igvn = _igvn;
@@ -3895,7 +3895,7 @@ PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, Gro
   bool finished = false;
   while(!finished) {
     while (idx < phi->req()) {
-      Node *mem = find_inst_mem(phi->in(idx), alias_idx, orig_phi_worklist);
+      Node *mem = find_inst_mem(phi->in(idx), alias_idx, orig_phi_worklist, rec_depth + 1);
       if (mem != nullptr && mem->is_Phi()) {
         PhiNode *newphi = create_split_phi(mem->as_Phi(), alias_idx, orig_phi_worklist, new_phi_created);
         if (new_phi_created) {
@@ -4037,7 +4037,12 @@ void ConnectionGraph::move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phi
 // Search memory chain of "mem" to find a MemNode whose address
 // is the specified alias index.
 //
-Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArray<PhiNode *>  &orig_phis) {
+#define FIND_INST_MEM_RECURSION_DEPTH_LIMIT 1000
+Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArray<PhiNode *>  &orig_phis, uint rec_depth) {
+  if (rec_depth > FIND_INST_MEM_RECURSION_DEPTH_LIMIT) {
+    _compile->record_failure(_invocation > 0 ? C2Compiler::retry_no_iterative_escape_analysis() : C2Compiler::retry_no_escape_analysis());
+    return nullptr;
+  }
   if (orig_mem == nullptr) {
     return orig_mem;
   }
@@ -4111,7 +4116,7 @@ Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArra
       if (result == mmem->base_memory()) {
         // Didn't find instance memory, search through general slice recursively.
         result = mmem->memory_at(C->get_general_index(alias_idx));
-        result = find_inst_mem(result, alias_idx, orig_phis);
+        result = find_inst_mem(result, alias_idx, orig_phis, rec_depth + 1);
         if (C->failing()) {
           return nullptr;
         }
@@ -4179,7 +4184,7 @@ Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArra
       orig_phis.append_if_missing(mphi);
     } else if (C->get_alias_index(t) != alias_idx) {
       // Create a new Phi with the specified alias index type.
-      result = split_memory_phi(mphi, alias_idx, orig_phis);
+      result = split_memory_phi(mphi, alias_idx, orig_phis, rec_depth + 1);
     }
   }
   // the result is either MemNode, PhiNode, InitializeNode.
diff --git a/src/hotspot/share/opto/escape.hpp b/src/hotspot/share/opto/escape.hpp
index 658c8f6e8fe..32e70be219a 100644
--- a/src/hotspot/share/opto/escape.hpp
+++ b/src/hotspot/share/opto/escape.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -549,10 +549,10 @@ class ConnectionGraph: public ArenaObj {
   bool split_AddP(Node *addp, Node *base);
 
   PhiNode *create_split_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, bool &new_created);
-  PhiNode *split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist);
+  PhiNode *split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, uint rec_depth);
 
   void  move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phis);
-  Node* find_inst_mem(Node* mem, int alias_idx,GrowableArray<PhiNode *>  &orig_phi_worklist);
+  Node* find_inst_mem(Node* mem, int alias_idx,GrowableArray<PhiNode *>  &orig_phi_worklist, uint rec_depth = 0);
   Node* step_through_mergemem(MergeMemNode *mmem, int alias_idx, const TypeOopPtr *toop);
 
   Node_Array _node_map; // used for bookkeeping during type splitting
diff --git a/src/hotspot/share/opto/loopPredicate.cpp b/src/hotspot/share/opto/loopPredicate.cpp
index f8d3fa0b6d9..b22931e5663 100644
--- a/src/hotspot/share/opto/loopPredicate.cpp
+++ b/src/hotspot/share/opto/loopPredicate.cpp
@@ -1341,8 +1341,8 @@ IfTrueNode* PhaseIdealLoop::add_template_assertion_predicate(IfNode* iff, IdealL
   // init + (current stride - initial stride) is within the loop so narrow its type by leveraging the type of the iv Phi
   const Type* type_iv = loop->_head->as_CountedLoop()->phi()->bottom_type();
   assert(!type_iv->is_int()->is_con(), "constant indicates one loop iteration for which we bailed out earlier");
-  max_value = new CastIINode(max_value, type_iv);
-  register_new_node(max_value, parse_predicate_proj);
+  max_value = new CastIINode(new_proj, max_value, type_iv);
+  register_new_node(max_value, new_proj);
 
   bol = rc_predicate(new_proj, scale, offset, max_value, limit, stride, rng, (stride > 0) != (scale > 0),
                      overflow);
diff --git a/src/hotspot/share/opto/loopTransform.cpp b/src/hotspot/share/opto/loopTransform.cpp
index 1b29d31ba68..6ca7bb51fb4 100644
--- a/src/hotspot/share/opto/loopTransform.cpp
+++ b/src/hotspot/share/opto/loopTransform.cpp
@@ -2871,6 +2871,7 @@ void PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
   // Must know if its a count-up or count-down loop
 
   int stride_con = cl->stride_con();
+  bool abs_stride_is_one = stride_con == 1 || stride_con == -1;
   Node* zero = _igvn.longcon(0);
   Node* one  = _igvn.longcon(1);
   // Use symmetrical int range [-max_jint,max_jint]
@@ -2882,6 +2883,15 @@ void PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
   Node* loop_entry = cl->skip_strip_mined()->in(LoopNode::EntryControl);
   assert(loop_entry->is_Proj() && loop_entry->in(0)->is_If(), "if projection only");
 
+  // if abs(stride) == 1, an Assertion Predicate for the final iv value is added. We don't know the final iv value until
+  // we're done with range check elimination so use a place holder.
+  Node* final_iv_placeholder = nullptr;
+  if (abs_stride_is_one) {
+    final_iv_placeholder = new Node(1);
+    _igvn.set_type(final_iv_placeholder, TypeInt::INT);
+    final_iv_placeholder->init_req(0, loop_entry);
+  }
+
   // Check loop body for tests of trip-counter plus loop-invariant vs loop-variant.
   for (uint i = 0; i < loop->_body.size(); i++) {
     Node *iff = loop->_body[i];
@@ -2985,6 +2995,20 @@ void PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
           Node* opaque_init = new OpaqueLoopInitNode(C, init);
           register_new_node(opaque_init, loop_entry);
 
+          if (abs_stride_is_one) {
+            // If the main loop becomes empty and the array access for this range check is sunk out of the loop, the index
+            // for the array access will be set to the index value of the final iteration which could be out of loop.
+            // Add an Assertion Predicate for that corner case. The final iv is computed from LoopLimit which is the
+            // LoopNode::limit() only if abs(stride) == 1 otherwise the computation depends on LoopNode::init_trip() as
+            // well. When LoopLimit only depends on LoopNode::limit(), there are cases where the zero trip guard for the
+            // main loop doesn't constant fold after range check elimination but, the array access for the final
+            // iteration of the main loop is out of bound and the index for that access is out of range for the range
+            // check CastII.
+            loop_entry = add_range_check_elimination_assertion_predicate(loop, loop_entry, scale_con, int_offset,
+                                                                         int_limit, stride_con, final_iv_placeholder, false);
+            assert(!assertion_predicate_has_loop_opaque_node(loop_entry->in(0)->as_If()), "unexpected");
+          }
+
           // Initialized Assertion Predicate for the value of the initial main-loop.
           loop_entry = add_range_check_elimination_assertion_predicate(loop, loop_entry, scale_con, int_offset,
                                                                        int_limit, stride_con, init, false);
@@ -3004,7 +3028,7 @@ void PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
           max_value = new AddINode(opaque_init, max_value);
           register_new_node(max_value, loop_entry);
           // init + (current stride - initial stride) is within the loop so narrow its type by leveraging the type of the iv Phi
-          max_value = new CastIINode(max_value, loop->_head->as_CountedLoop()->phi()->bottom_type());
+          max_value = new CastIINode(loop_entry, max_value, loop->_head->as_CountedLoop()->phi()->bottom_type());
           register_new_node(max_value, loop_entry);
           loop_entry = add_range_check_elimination_assertion_predicate(
               loop, loop_entry, scale_con, int_offset, int_limit, stride_con, max_value, true
@@ -3116,11 +3140,14 @@ void PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
   register_new_node(main_limit, pre_ctrl);
   // Hack the now-private loop bounds
   _igvn.replace_input_of(main_cmp, 2, main_limit);
+  if (abs_stride_is_one) {
+    Node* final_iv = new SubINode(main_limit, cl->stride());
+    register_new_node(final_iv, loop_entry);
+    _igvn.replace_node(final_iv_placeholder, final_iv);
+  }
   // The OpaqueNode is unshared by design
   assert(opqzm->outcnt() == 1, "cannot hack shared node");
   _igvn.replace_input_of(opqzm, 1, main_limit);
-
-  return;
 }
 
 bool IdealLoopTree::compute_has_range_checks() const {
diff --git a/src/hotspot/share/opto/loopnode.cpp b/src/hotspot/share/opto/loopnode.cpp
index 85e6f03d428..45e59f4e216 100644
--- a/src/hotspot/share/opto/loopnode.cpp
+++ b/src/hotspot/share/opto/loopnode.cpp
@@ -5248,6 +5248,7 @@ bool IdealLoopTree::verify_tree(IdealLoopTree* loop_verify) const {
 
 //------------------------------set_idom---------------------------------------
 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
+  _nesting.check(); // Check if a potential reallocation in the resource arena is safe
   uint idx = d->_idx;
   if (idx >= _idom_size) {
     uint newsize = next_power_of_2(idx);
diff --git a/src/hotspot/share/opto/loopnode.hpp b/src/hotspot/share/opto/loopnode.hpp
index 7d78bf5021c..24101ea07a0 100644
--- a/src/hotspot/share/opto/loopnode.hpp
+++ b/src/hotspot/share/opto/loopnode.hpp
@@ -611,6 +611,7 @@ class IdealLoopTree : public ResourceObj {
       _head(head), _tail(tail),
       _phase(phase),
       _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
+      _body(Compile::current()->comp_arena()),
       _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
       _has_range_checks(0), _has_range_checks_computed(0),
       _safepts(nullptr),
@@ -840,6 +841,8 @@ class PhaseIdealLoop : public PhaseTransform {
   uint *_preorders;
   uint _max_preorder;
 
+  ReallocMark _nesting; // Safety checks for arena reallocation
+
   const PhaseIdealLoop* _verify_me;
   bool _verify_only;
 
@@ -852,6 +855,7 @@ class PhaseIdealLoop : public PhaseTransform {
 
   // Allocate _preorders[] array
   void reallocate_preorders() {
+    _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
     if ( _max_preorder < C->unique() ) {
       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
       _max_preorder = C->unique();
@@ -862,6 +866,7 @@ class PhaseIdealLoop : public PhaseTransform {
   // Check to grow _preorders[] array for the case when build_loop_tree_impl()
   // adds new nodes.
   void check_grow_preorders( ) {
+    _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
     if ( _max_preorder < C->unique() ) {
       uint newsize = _max_preorder<<1;  // double size of array
       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
diff --git a/src/hotspot/share/opto/loopopts.cpp b/src/hotspot/share/opto/loopopts.cpp
index ba0ce344122..361e03f06a2 100644
--- a/src/hotspot/share/opto/loopopts.cpp
+++ b/src/hotspot/share/opto/loopopts.cpp
@@ -4670,6 +4670,9 @@ void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
   _phase->igvn().register_new_node_with_optimizer(clone);
   _orig_to_new.put(node, clone);
   _phase->set_ctrl(clone, new_ctrl);
+  if (node->is_CastII()) {
+    clone->set_req(0, new_ctrl);
+  }
 }
 
 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
diff --git a/src/hotspot/share/opto/machnode.cpp b/src/hotspot/share/opto/machnode.cpp
index 57361313f85..39b804f7e5c 100644
--- a/src/hotspot/share/opto/machnode.cpp
+++ b/src/hotspot/share/opto/machnode.cpp
@@ -395,7 +395,14 @@ const class TypePtr *MachNode::adr_type() const {
     // 32-bit unscaled narrow oop can be the base of any address expression
     t = t->make_ptr();
   }
-  if (t->isa_intptr_t() && offset != 0 && offset != Type::OffsetBot) {
+
+  if (t->isa_intptr_t() &&
+#if !defined(AARCH64)
+      // AArch64 supports the addressing mode:
+      // [base, 0], in which [base] is converted from a long value
+      offset != 0 &&
+#endif
+      offset != Type::OffsetBot) {
     // We cannot assert that the offset does not look oop-ish here.
     // Depending on the heap layout the cardmark base could land
     // inside some oopish region.  It definitely does for Win2K.
diff --git a/src/hotspot/share/opto/memnode.cpp b/src/hotspot/share/opto/memnode.cpp
index 438dc5c1f64..c7f0fb9fc32 100644
--- a/src/hotspot/share/opto/memnode.cpp
+++ b/src/hotspot/share/opto/memnode.cpp
@@ -2723,13 +2723,13 @@ uint StoreNode::hash() const {
 //
 class ArrayPointer {
 private:
-  const bool _is_valid;          // The parsing succeeded
   const Node* _pointer;          // The final pointer to the position in the array
   const Node* _base;             // Base address of the array
   const jlong _constant_offset;  // Sum of collected constant offsets
   const Node* _int_offset;       // (optional) Offset behind LShiftL and ConvI2L
-  const jint  _int_offset_shift; // (optional) Shift value for int_offset
   const GrowableArray<Node*>* _other_offsets; // List of other AddP offsets
+  const jint _int_offset_shift; // (optional) Shift value for int_offset
+  const bool _is_valid;          // The parsing succeeded
 
   ArrayPointer(const bool is_valid,
                const Node* pointer,
@@ -2738,13 +2738,13 @@ class ArrayPointer {
                const Node* int_offset,
                const jint int_offset_shift,
                const GrowableArray<Node*>* other_offsets) :
-      _is_valid(is_valid),
       _pointer(pointer),
       _base(base),
       _constant_offset(constant_offset),
       _int_offset(int_offset),
+      _other_offsets(other_offsets),
       _int_offset_shift(int_offset_shift),
-      _other_offsets(other_offsets)
+      _is_valid(is_valid)
   {
     assert(_pointer != nullptr, "must always have pointer");
     assert(is_valid == (_base != nullptr), "have base exactly if valid");
diff --git a/src/hotspot/share/opto/movenode.cpp b/src/hotspot/share/opto/movenode.cpp
index eb0a914b994..dc65afff26f 100644
--- a/src/hotspot/share/opto/movenode.cpp
+++ b/src/hotspot/share/opto/movenode.cpp
@@ -91,17 +91,20 @@ Node *CMoveNode::Ideal(PhaseGVN *phase, bool can_reshape) {
       phase->type(in(IfTrue))    == Type::TOP) {
     return nullptr;
   }
-  // Canonicalize the node by moving constants to the right input.
-  if (in(Condition)->is_Bool() && phase->type(in(IfFalse))->singleton() && !phase->type(in(IfTrue))->singleton()) {
-    BoolNode* b = in(Condition)->as_Bool()->negate(phase);
-    return make(in(Control), phase->transform(b), in(IfTrue), in(IfFalse), _type);
-  }
 
+  // Check for Min/Max patterns. This is called before constants are pushed to the right input, as that transform can
+  // make BoolTests non-canonical.
   Node* minmax = Ideal_minmax(phase, this);
   if (minmax != nullptr) {
     return minmax;
   }
 
+  // Canonicalize the node by moving constants to the right input.
+  if (in(Condition)->is_Bool() && phase->type(in(IfFalse))->singleton() && !phase->type(in(IfTrue))->singleton()) {
+    BoolNode* b = in(Condition)->as_Bool()->negate(phase);
+    return make(in(Control), phase->transform(b), in(IfTrue), in(IfFalse), _type);
+  }
+
   return nullptr;
 }
 
diff --git a/src/hotspot/share/opto/node.cpp b/src/hotspot/share/opto/node.cpp
index 6cf6ff2094e..f36770e67ea 100644
--- a/src/hotspot/share/opto/node.cpp
+++ b/src/hotspot/share/opto/node.cpp
@@ -2766,6 +2766,10 @@ const RegMask &Node::in_RegMask(uint) const {
 }
 
 void Node_Array::grow(uint i) {
+  _nesting.check(_a); // Check if a potential reallocation in the arena is safe
+  if (i < _max) {
+    return; // No need to grow
+  }
   assert(_max > 0, "invariant");
   uint old = _max;
   _max = next_power_of_2(i);
@@ -2973,6 +2977,10 @@ void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
 
 //=============================================================================
 void Node_Stack::grow() {
+  _nesting.check(_a); // Check if a potential reallocation in the arena is safe
+  if (_inode_top < _inode_max) {
+    return; // No need to grow
+  }
   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
   size_t max = old_max << 1;             // max * 2
diff --git a/src/hotspot/share/opto/node.hpp b/src/hotspot/share/opto/node.hpp
index ae379c4833a..10e1e7b1006 100644
--- a/src/hotspot/share/opto/node.hpp
+++ b/src/hotspot/share/opto/node.hpp
@@ -1596,6 +1596,8 @@ class Node_Array : public AnyObj {
   Arena* _a;                    // Arena to allocate in
   uint   _max;
   Node** _nodes;
+  ReallocMark _nesting;         // Safety checks for arena reallocation
+
   void   grow( uint i );        // Grow array node to fit
 public:
   Node_Array(Arena* a, uint max = OptoNodeListSize) : _a(a), _max(max) {
@@ -1614,7 +1616,7 @@ class Node_Array : public AnyObj {
   Node* at(uint i) const { assert(i<_max,"oob"); return _nodes[i]; }
   Node** adr() { return _nodes; }
   // Extend the mapping: index i maps to Node *n.
-  void map( uint i, Node *n ) { if( i>=_max ) grow(i); _nodes[i] = n; }
+  void map( uint i, Node *n ) { grow(i); _nodes[i] = n; }
   void insert( uint i, Node *n );
   void remove( uint i );        // Remove, preserving order
   // Clear all entries in _nodes to null but keep storage
@@ -1844,6 +1846,7 @@ class Node_Stack {
   INode *_inode_max; // End of _inodes == _inodes + _max
   INode *_inodes;    // Array storage for the stack
   Arena *_a;         // Arena to allocate in
+  ReallocMark _nesting; // Safety checks for arena reallocation
   void grow();
 public:
   Node_Stack(int size) {
@@ -1867,7 +1870,7 @@ class Node_Stack {
   }
   void push(Node *n, uint i) {
     ++_inode_top;
-    if (_inode_top >= _inode_max) grow();
+    grow();
     INode *top = _inode_top; // optimization
     top->node = n;
     top->indx = i;
diff --git a/src/hotspot/share/opto/phaseX.cpp b/src/hotspot/share/opto/phaseX.cpp
index 96e9f108808..dae4a5c68a3 100644
--- a/src/hotspot/share/opto/phaseX.cpp
+++ b/src/hotspot/share/opto/phaseX.cpp
@@ -2351,6 +2351,7 @@ void Node::replace_by(Node *new_node) {
 //=============================================================================
 //-----------------------------------------------------------------------------
 void Type_Array::grow( uint i ) {
+  assert(_a == Compile::current()->comp_arena(), "Should be allocated in comp_arena");
   if( !_max ) {
     _max = 1;
     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
diff --git a/src/hotspot/share/opto/vector.cpp b/src/hotspot/share/opto/vector.cpp
index 1b4d64e20b1..9ab62c282d1 100644
--- a/src/hotspot/share/opto/vector.cpp
+++ b/src/hotspot/share/opto/vector.cpp
@@ -184,7 +184,7 @@ void PhaseVector::scalarize_vbox_node(VectorBoxNode* vec_box) {
   // Process merged VBAs
 
   if (EnableVectorAggressiveReboxing) {
-    Unique_Node_List calls(C->comp_arena());
+    Unique_Node_List calls;
     for (DUIterator_Fast imax, i = vec_box->fast_outs(imax); i < imax; i++) {
       Node* use = vec_box->fast_out(i);
       if (use->is_CallJava()) {
@@ -238,9 +238,9 @@ void PhaseVector::scalarize_vbox_node(VectorBoxNode* vec_box) {
   }
 
   // Process debug uses at safepoints
-  Unique_Node_List safepoints(C->comp_arena());
+  Unique_Node_List safepoints;
 
-  Unique_Node_List worklist(C->comp_arena());
+  Unique_Node_List worklist;
   worklist.push(vec_box);
   while (worklist.size() > 0) {
     Node* n = worklist.pop();
diff --git a/src/hotspot/share/opto/vectorIntrinsics.cpp b/src/hotspot/share/opto/vectorIntrinsics.cpp
index b31f6ace5a6..cfcd903e79d 100644
--- a/src/hotspot/share/opto/vectorIntrinsics.cpp
+++ b/src/hotspot/share/opto/vectorIntrinsics.cpp
@@ -2484,12 +2484,10 @@ bool LibraryCallKit::inline_vector_insert() {
   // Convert insert value back to its appropriate type.
   switch (elem_bt) {
     case T_BYTE:
-      insert_val = gvn().transform(new ConvL2INode(insert_val));
-      insert_val = gvn().transform(new CastIINode(insert_val, TypeInt::BYTE));
+      insert_val = gvn().transform(new ConvL2INode(insert_val, TypeInt::BYTE));
       break;
     case T_SHORT:
-      insert_val = gvn().transform(new ConvL2INode(insert_val));
-      insert_val = gvn().transform(new CastIINode(insert_val, TypeInt::SHORT));
+      insert_val = gvn().transform(new ConvL2INode(insert_val, TypeInt::SHORT));
       break;
     case T_INT:
       insert_val = gvn().transform(new ConvL2INode(insert_val));
diff --git a/src/hotspot/share/prims/jni.cpp b/src/hotspot/share/prims/jni.cpp
index ae040d66138..a91d7375761 100644
--- a/src/hotspot/share/prims/jni.cpp
+++ b/src/hotspot/share/prims/jni.cpp
@@ -1148,7 +1148,7 @@ JNI_ENTRY(ResultType, \
           jni_Call##Result##Method(JNIEnv *env, jobject obj, jmethodID methodID, ...)) \
 \
   EntryProbe; \
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, Call##Result##Method, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1203,7 +1203,7 @@ JNI_ENTRY(ResultType, \
           jni_Call##Result##MethodV(JNIEnv *env, jobject obj, jmethodID methodID, va_list args)) \
 \
   EntryProbe;\
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, Call##Result##MethodV, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1254,7 +1254,7 @@ DEFINE_CALLMETHODV(jdouble,  Double,  T_DOUBLE
 JNI_ENTRY(ResultType, \
           jni_Call##Result##MethodA(JNIEnv *env, jobject obj, jmethodID methodID, const jvalue *args)) \
   EntryProbe; \
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, Call##Result##MethodA, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1546,7 +1546,7 @@ JNI_ENTRY(ResultType, \
           jni_CallStatic##Result##Method(JNIEnv *env, jclass cls, jmethodID methodID, ...)) \
 \
   EntryProbe; \
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, CallStatic##Result##Method, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1601,7 +1601,7 @@ JNI_ENTRY(ResultType, \
           jni_CallStatic##Result##MethodV(JNIEnv *env, jclass cls, jmethodID methodID, va_list args)) \
 \
   EntryProbe; \
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, CallStatic##Result##MethodV, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1657,7 +1657,7 @@ JNI_ENTRY(ResultType, \
           jni_CallStatic##Result##MethodA(JNIEnv *env, jclass cls, jmethodID methodID, const jvalue *args)) \
 \
   EntryProbe; \
-  ResultType ret = 0;\
+  ResultType ret{}; \
   DT_RETURN_MARK_FOR(Result, CallStatic##Result##MethodA, ResultType, \
                      (const ResultType&)ret);\
 \
@@ -1750,7 +1750,7 @@ DT_RETURN_MARK_DECL(GetFieldID, jfieldID
 JNI_ENTRY(jfieldID, jni_GetFieldID(JNIEnv *env, jclass clazz,
           const char *name, const char *sig))
   HOTSPOT_JNI_GETFIELDID_ENTRY(env, clazz, (char *) name, (char *) sig);
-  jfieldID ret = 0;
+  jfieldID ret = nullptr;
   DT_RETURN_MARK(GetFieldID, jfieldID, (const jfieldID&)ret);
 
   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz));
@@ -3035,12 +3035,12 @@ extern "C" void* JNICALL jni_GetDirectBufferAddress(JNIEnv *env, jobject buf)
 
   if (!directBufferSupportInitializeEnded) {
     if (!initializeDirectBufferSupport(env, thread)) {
-      return 0;
+      return nullptr;
     }
   }
 
   if ((buf != nullptr) && (!env->IsInstanceOf(buf, directBufferClass))) {
-    return 0;
+    return nullptr;
   }
 
   ret = (void*)(intptr_t)env->GetLongField(buf, directBufferAddressField);
@@ -3647,8 +3647,8 @@ static jint JNI_CreateJavaVM_inner(JavaVM **vm, void **penv, void *args) {
     }
 
     // Creation failed. We must reset vm_created
-    *vm = 0;
-    *(JNIEnv**)penv = 0;
+    *vm = nullptr;
+    *(JNIEnv**)penv = nullptr;
     // reset vm_created last to avoid race condition. Use OrderAccess to
     // control both compiler and architectural-based reordering.
     assert(vm_created == IN_PROGRESS, "must be");
diff --git a/src/hotspot/share/prims/jvm.cpp b/src/hotspot/share/prims/jvm.cpp
index 7a8c07477dc..4f63ebdf9d5 100644
--- a/src/hotspot/share/prims/jvm.cpp
+++ b/src/hotspot/share/prims/jvm.cpp
@@ -3119,14 +3119,6 @@ JVM_ENTRY(jobject, JVM_GetStackTrace(JNIEnv *env, jobject jthread))
   return JNIHandles::make_local(THREAD, trace);
 JVM_END
 
-JVM_ENTRY(void, JVM_DumpAllStacks(JNIEnv* env, jclass))
-  VM_PrintThreads op;
-  VMThread::execute(&op);
-  if (JvmtiExport::should_post_data_dump()) {
-    JvmtiExport::post_data_dump();
-  }
-JVM_END
-
 JVM_ENTRY(void, JVM_SetNativeThreadName(JNIEnv* env, jobject jthread, jstring name))
   // We don't use a ThreadsListHandle here because the current thread
   // must be alive.
@@ -3755,7 +3747,7 @@ JVM_ENTRY(jobjectArray, JVM_DumpThreads(JNIEnv *env, jclass threadClass, jobject
 
   // Check if threads is null
   if (threads == nullptr) {
-    THROW_(vmSymbols::java_lang_NullPointerException(), 0);
+    THROW_NULL(vmSymbols::java_lang_NullPointerException());
   }
 
   objArrayOop a = objArrayOop(JNIHandles::resolve_non_null(threads));
@@ -3763,13 +3755,13 @@ JVM_ENTRY(jobjectArray, JVM_DumpThreads(JNIEnv *env, jclass threadClass, jobject
   int num_threads = ah->length();
   // check if threads is non-empty array
   if (num_threads == 0) {
-    THROW_(vmSymbols::java_lang_IllegalArgumentException(), 0);
+    THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
   }
 
   // check if threads is not an array of objects of Thread class
   Klass* k = ObjArrayKlass::cast(ah->klass())->element_klass();
   if (k != vmClasses::Thread_klass()) {
-    THROW_(vmSymbols::java_lang_IllegalArgumentException(), 0);
+    THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
   }
 
   ResourceMark rm(THREAD);
diff --git a/src/hotspot/share/prims/jvmtiClassFileReconstituter.cpp b/src/hotspot/share/prims/jvmtiClassFileReconstituter.cpp
index 8d7ffdf4835..ceed1d8ad95 100644
--- a/src/hotspot/share/prims/jvmtiClassFileReconstituter.cpp
+++ b/src/hotspot/share/prims/jvmtiClassFileReconstituter.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -119,10 +119,10 @@ void JvmtiClassFileReconstituter::write_field_infos() {
       write_signature_attribute(generic_signature_index);
     }
     if (anno != nullptr) {
-      write_annotations_attribute("RuntimeVisibleAnnotations", "RuntimeInvisibleAnnotations", anno);
+      write_annotations_attribute("RuntimeVisibleAnnotations", anno);
     }
     if (type_anno != nullptr) {
-      write_annotations_attribute("RuntimeVisibleTypeAnnotations", "RuntimeInvisibleTypeAnnotations", type_anno);
+      write_annotations_attribute("RuntimeVisibleTypeAnnotations", type_anno);
     }
   }
 }
@@ -380,20 +380,6 @@ void JvmtiClassFileReconstituter::write_annotations_attribute(const char* attr_n
   memcpy(writeable_address(length), annos->adr_at(0), length);
 }
 
-void JvmtiClassFileReconstituter::write_annotations_attribute(const char* attr_name,
-                                                              const char* fallback_attr_name,
-                                                              AnnotationArray* annos) {
-  TempNewSymbol sym = SymbolTable::probe(attr_name, (int)strlen(attr_name));
-  if (sym != nullptr) {
-    if (symbol_to_cpool_index(sym) != 0) {
-      write_annotations_attribute(attr_name, annos);
-      return;
-    }
-  }
-  // use fallback name
-  write_annotations_attribute(fallback_attr_name, annos);
-}
-
 //  BootstrapMethods_attribute {
 //    u2 attribute_name_index;
 //    u4 attribute_length;
@@ -533,10 +519,10 @@ void JvmtiClassFileReconstituter::write_record_attribute() {
       write_signature_attribute(component->generic_signature_index());
     }
     if (component->annotations() != nullptr) {
-      write_annotations_attribute("RuntimeVisibleAnnotations", "RuntimeInvisibleAnnotations", component->annotations());
+      write_annotations_attribute("RuntimeVisibleAnnotations", component->annotations());
     }
     if (component->type_annotations() != nullptr) {
-      write_annotations_attribute("RuntimeVisibleTypeAnnotations", "RuntimeInvisibleTypeAnnotations", component->type_annotations());
+      write_annotations_attribute("RuntimeVisibleTypeAnnotations", component->type_annotations());
     }
   }
 }
@@ -775,13 +761,13 @@ void JvmtiClassFileReconstituter::write_method_info(const methodHandle& method)
     write_signature_attribute(generic_signature_index);
   }
   if (anno != nullptr) {
-    write_annotations_attribute("RuntimeVisibleAnnotations", "RuntimeInvisibleAnnotations", anno);
+    write_annotations_attribute("RuntimeVisibleAnnotations", anno);
   }
   if (param_anno != nullptr) {
-    write_annotations_attribute("RuntimeVisibleParameterAnnotations", "RuntimeInvisibleParameterAnnotations", param_anno);
+    write_annotations_attribute("RuntimeVisibleParameterAnnotations", param_anno);
   }
   if (type_anno != nullptr) {
-    write_annotations_attribute("RuntimeVisibleTypeAnnotations", "RuntimeInvisibleTypeAnnotations", type_anno);
+    write_annotations_attribute("RuntimeVisibleTypeAnnotations", type_anno);
   }
 }
 
@@ -841,10 +827,10 @@ void JvmtiClassFileReconstituter::write_class_attributes() {
     write_source_debug_extension_attribute();
   }
   if (anno != nullptr) {
-    write_annotations_attribute("RuntimeVisibleAnnotations", "RuntimeInvisibleAnnotations", anno);
+    write_annotations_attribute("RuntimeVisibleAnnotations", anno);
   }
   if (type_anno != nullptr) {
-    write_annotations_attribute("RuntimeVisibleTypeAnnotations", "RuntimeInvisibleTypeAnnotations", type_anno);
+    write_annotations_attribute("RuntimeVisibleTypeAnnotations", type_anno);
   }
   if (ik()->nest_host_index() != 0) {
     write_nest_host_attribute();
diff --git a/src/hotspot/share/prims/jvmtiClassFileReconstituter.hpp b/src/hotspot/share/prims/jvmtiClassFileReconstituter.hpp
index 2f36a2877d2..015042a8543 100644
--- a/src/hotspot/share/prims/jvmtiClassFileReconstituter.hpp
+++ b/src/hotspot/share/prims/jvmtiClassFileReconstituter.hpp
@@ -117,13 +117,6 @@ class JvmtiClassFileReconstituter : public JvmtiConstantPoolReconstituter {
   void write_signature_attribute(u2 generic_signaure_index);
   void write_attribute_name_index(const char* name);
   void write_annotations_attribute(const char* attr_name, AnnotationArray* annos);
-  // With PreserveAllAnnotations option "runtime invisible" annotations
-  // (RuntimeInvisibleAnnotations/RuntimeInvisibleTypeAnnotations/RuntimeInvisibleParameterAnnotations)
-  // are considered "runtime visible" and ClassFileReconstituter writes them as
-  // RuntimeVisibleAnnotations/RuntimeVisibleTypeAnnotations/RuntimeVisibleParameterAnnotations.
-  // This helper method is for the corner case when "runtime visible" attribute name is not presents
-  // in the class constant pool and the annotations are written with fallback "runtime invisible" name.
-  void write_annotations_attribute(const char* attr_name, const char* fallback_attr_name, AnnotationArray* annos);
   void write_bootstrapmethod_attribute();
   void write_nest_host_attribute();
   void write_nest_members_attribute();
diff --git a/src/hotspot/share/prims/jvmtiExport.cpp b/src/hotspot/share/prims/jvmtiExport.cpp
index c2b6d27986b..f79116f5ebe 100644
--- a/src/hotspot/share/prims/jvmtiExport.cpp
+++ b/src/hotspot/share/prims/jvmtiExport.cpp
@@ -2068,7 +2068,7 @@ void JvmtiExport::post_exception_throw(JavaThread *thread, Method* method, addre
 
         jmethodID catch_jmethodID;
         if (current_bci < 0) {
-          catch_jmethodID = 0;
+          catch_jmethodID = nullptr;
           current_bci = 0;
         } else {
           catch_jmethodID = jem.to_jmethodID(current_mh);
@@ -2105,8 +2105,8 @@ void JvmtiExport::notice_unwind_due_to_exception(JavaThread *thread, Method* met
                      JvmtiTrace::safe_get_thread_name(thread),
                      (mh() == nullptr) ? "null" : mh()->klass_name()->as_C_string(),
                      (mh() == nullptr) ? "null" : mh()->name()->as_C_string(),
-                     location==0? "no location:" : "",
-                     location==0? 0 : location - mh()->code_base(),
+                     location == nullptr ? "no location:" : "",
+                     location == nullptr ? 0 : location - mh()->code_base(),
                      in_handler_frame? "in handler frame" : "not handler frame" ));
 
   if (state->is_exception_detected()) {
diff --git a/src/hotspot/share/prims/jvmtiTrace.cpp b/src/hotspot/share/prims/jvmtiTrace.cpp
index 002f59957ea..c5fb95c931b 100644
--- a/src/hotspot/share/prims/jvmtiTrace.cpp
+++ b/src/hotspot/share/prims/jvmtiTrace.cpp
@@ -261,7 +261,7 @@ void JvmtiTrace::shutdown() {
 
 
 const char* JvmtiTrace::enum_name(const char** names, const jint* values, jint value) {
-  for (int index = 0; names[index] != 0; ++index) {
+  for (int index = 0; names[index] != nullptr; ++index) {
     if (values[index] == value) {
       return names[index];
     }
diff --git a/src/hotspot/share/prims/methodHandles.cpp b/src/hotspot/share/prims/methodHandles.cpp
index fd10f0723bf..473ac396997 100644
--- a/src/hotspot/share/prims/methodHandles.cpp
+++ b/src/hotspot/share/prims/methodHandles.cpp
@@ -436,7 +436,6 @@ Symbol* MethodHandles::signature_polymorphic_intrinsic_name(vmIntrinsics::ID iid
   case vmIntrinsics::_linkToNative:     return vmSymbols::linkToNative_name();
   default:
     fatal("unexpected intrinsic id: %d %s", vmIntrinsics::as_int(iid), vmIntrinsics::name_at(iid));
-    return 0;
   }
 }
 
@@ -449,7 +448,6 @@ Bytecodes::Code MethodHandles::signature_polymorphic_intrinsic_bytecode(vmIntrin
     case vmIntrinsics::_invokeBasic:     return Bytecodes::_invokehandle;
     default:
       fatal("unexpected id: (%d) %s", (uint)id, vmIntrinsics::name_at(id));
-      return Bytecodes::_illegal;
   }
 }
 
@@ -463,7 +461,6 @@ int MethodHandles::signature_polymorphic_intrinsic_ref_kind(vmIntrinsics::ID iid
   case vmIntrinsics::_linkToInterface:  return JVM_REF_invokeInterface;
   default:
     fatal("unexpected intrinsic id: %d %s", vmIntrinsics::as_int(iid), vmIntrinsics::name_at(iid));
-    return 0;
   }
 }
 
diff --git a/src/hotspot/share/prims/perf.cpp b/src/hotspot/share/prims/perf.cpp
index f10854b5294..9ff831dded9 100644
--- a/src/hotspot/share/prims/perf.cpp
+++ b/src/hotspot/share/prims/perf.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -68,7 +68,7 @@ PERF_ENTRY(jobject, Perf_Attach(JNIEnv *env, jobject unused, int vmid))
 
   PerfWrapper("Perf_Attach");
 
-  char* address = 0;
+  char* address = nullptr;
   size_t capacity = 0;
 
   // attach to the PerfData memory region for the specified VM
@@ -90,7 +90,7 @@ PERF_ENTRY(void, Perf_Detach(JNIEnv *env, jobject unused, jobject buffer))
     return;
   }
 
-  void* address = 0;
+  void* address = nullptr;
   jlong capacity = 0;
 
   // get buffer address and capacity
diff --git a/src/hotspot/share/prims/unsafe.cpp b/src/hotspot/share/prims/unsafe.cpp
index 942d9100c29..1be157b2e44 100644
--- a/src/hotspot/share/prims/unsafe.cpp
+++ b/src/hotspot/share/prims/unsafe.cpp
@@ -652,7 +652,7 @@ static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data
 
   jbyte *body;
   char *utfName = nullptr;
-  jclass result = 0;
+  jclass result = nullptr;
   char buf[128];
 
   assert(data != nullptr, "Class bytes must not be null");
@@ -665,7 +665,7 @@ static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data
   body = NEW_C_HEAP_ARRAY_RETURN_NULL(jbyte, length, mtInternal);
   if (body == nullptr) {
     throw_new(env, "java/lang/OutOfMemoryError");
-    return 0;
+    return nullptr;
   }
 
   env->GetByteArrayRegion(data, offset, length, body);
diff --git a/src/hotspot/share/prims/wbtestmethods/parserTests.cpp b/src/hotspot/share/prims/wbtestmethods/parserTests.cpp
index 2845aa9aa10..efcf2b070d0 100644
--- a/src/hotspot/share/prims/wbtestmethods/parserTests.cpp
+++ b/src/hotspot/share/prims/wbtestmethods/parserTests.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -127,6 +127,14 @@ static void fill_in_parser(DCmdParser* parser, oop argument)
      } else {
       parser->add_dcmd_option(argument);
      }
+   } else if (strcmp(type, "FILE") == 0) {
+      DCmdArgument<char*>* argument =
+          new DCmdArgument<char*>(name, desc, "FILE", mandatory);
+      if (isarg) {
+        parser->add_dcmd_argument(argument);
+      } else {
+        parser->add_dcmd_option(argument);
+      }
    }
 }
 
diff --git a/src/hotspot/share/runtime/arguments.cpp b/src/hotspot/share/runtime/arguments.cpp
index d353c5a162a..23b53300441 100644
--- a/src/hotspot/share/runtime/arguments.cpp
+++ b/src/hotspot/share/runtime/arguments.cpp
@@ -102,7 +102,7 @@ size_t Arguments::_default_SharedBaseAddress    = SharedBaseAddress;
 
 bool   Arguments::_enable_preview               = false;
 
-LegacyGCLogging Arguments::_legacyGCLogging     = { 0, 0 };
+LegacyGCLogging Arguments::_legacyGCLogging     = { nullptr, 0 };
 
 // These are not set by the JDK's built-in launchers, but they can be set by
 // programs that embed the JVM using JNI_CreateJavaVM. See comments around
@@ -503,7 +503,6 @@ static SpecialFlag const special_jvm_flags[] = {
   { "RequireSharedSpaces",          JDK_Version::jdk(18), JDK_Version::jdk(19), JDK_Version::undefined() },
   { "UseSharedSpaces",              JDK_Version::jdk(18), JDK_Version::jdk(19), JDK_Version::undefined() },
   { "DontYieldALot",                JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
-  { "PreserveAllAnnotations",       JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "UseNotificationThread",        JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "LockingMode",                  JDK_Version::jdk(24), JDK_Version::jdk(26), JDK_Version::jdk(27) },
   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
@@ -513,6 +512,7 @@ static SpecialFlag const special_jvm_flags[] = {
 
   { "MetaspaceReclaimPolicy",       JDK_Version::undefined(), JDK_Version::jdk(21), JDK_Version::undefined() },
 
+  { "PreserveAllAnnotations",       JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "UseEmptySlotsInSupers",        JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "OldSize",                      JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
 #if defined(X86)
@@ -521,6 +521,8 @@ static SpecialFlag const special_jvm_flags[] = {
   { "RTMRetryCount",                JDK_Version::jdk(23), JDK_Version::jdk(24), JDK_Version::jdk(25) },
 #endif // X86
 
+
+  { "BaseFootPrintEstimate",           JDK_Version::undefined(), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "HeapFirstMaximumCompactionCount", JDK_Version::undefined(), JDK_Version::jdk(24), JDK_Version::jdk(25) },
   { "UseVtableBasedCHA",               JDK_Version::undefined(), JDK_Version::jdk(24), JDK_Version::jdk(25) },
 #ifdef ASSERT
@@ -1653,9 +1655,6 @@ jint Arguments::set_aggressive_heap_flags() {
 #endif
 
   // Increase some data structure sizes for efficiency
-  if (FLAG_SET_CMDLINE(BaseFootPrintEstimate, MaxHeapSize) != JVMFlag::SUCCESS) {
-    return JNI_EINVAL;
-  }
   if (FLAG_SET_CMDLINE(ResizeTLAB, false) != JVMFlag::SUCCESS) {
     return JNI_EINVAL;
   }
@@ -1850,11 +1849,11 @@ bool Arguments::is_bad_option(const JavaVMOption* option, jboolean ignore,
 }
 
 static const char* user_assertion_options[] = {
-  "-da", "-ea", "-disableassertions", "-enableassertions", 0
+  "-da", "-ea", "-disableassertions", "-enableassertions", nullptr
 };
 
 static const char* system_assertion_options[] = {
-  "-dsa", "-esa", "-disablesystemassertions", "-enablesystemassertions", 0
+  "-dsa", "-esa", "-disablesystemassertions", "-enablesystemassertions", nullptr
 };
 
 bool Arguments::parse_uint(const char* value,
diff --git a/src/hotspot/share/runtime/continuationFreezeThaw.cpp b/src/hotspot/share/runtime/continuationFreezeThaw.cpp
index 87f60debc14..0e4640b6a9f 100644
--- a/src/hotspot/share/runtime/continuationFreezeThaw.cpp
+++ b/src/hotspot/share/runtime/continuationFreezeThaw.cpp
@@ -1865,7 +1865,7 @@ int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &arg
   const int frame_size = f.cb()->frame_size();
   argsize = f.stack_argsize();
 
-  f.next(SmallRegisterMap::instance, true /* stop */);
+  f.next(SmallRegisterMap::instance(), true /* stop */);
   empty = f.is_done();
   assert(!empty || argsize == chunk->argsize(), "");
 
@@ -2075,7 +2075,7 @@ bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
 
   int argsize = _stream.stack_argsize();
 
-  _stream.next(SmallRegisterMap::instance);
+  _stream.next(SmallRegisterMap::instance());
   assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
 
   // we never leave a compiled caller of an interpreted frame as the top frame in the chunk
@@ -2183,7 +2183,7 @@ NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& c
   assert(hf.is_interpreted_frame(), "");
 
   if (UNLIKELY(seen_by_gc())) {
-    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
+    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
   }
 
   const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
@@ -2226,7 +2226,7 @@ NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& c
 
   if (!is_bottom_frame) {
     // can only fix caller once this frame is thawed (due to callee saved regs)
-    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
+    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
   } else if (_cont.tail()->has_bitmap() && locals > 0) {
     assert(hf.is_heap_frame(), "should be");
     address start = (address)(heap_frame_bottom - locals);
@@ -2243,7 +2243,7 @@ void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int n
   assert(_cont.is_preempted() || !stub_caller, "stub caller not at preemption");
 
   if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
-    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
+    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
   }
 
   const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
@@ -2302,7 +2302,7 @@ void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int n
 
   if (!is_bottom_frame) {
     // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
-    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
+    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
   } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
     address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
     int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
@@ -2384,7 +2384,7 @@ void ThawBase::finish_thaw(frame& f) {
     f.set_sp(align_down(f.sp(), frame::frame_alignment));
   }
   push_return_frame(f);
-  chunk->fix_thawed_frame(f, SmallRegisterMap::instance); // can only fix caller after push_return_frame (due to callee saved regs)
+  chunk->fix_thawed_frame(f, SmallRegisterMap::instance()); // can only fix caller after push_return_frame (due to callee saved regs)
 
   assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
 
@@ -2450,8 +2450,8 @@ static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::th
   intptr_t* const sp = thw.thaw(kind);
   assert(is_aligned(sp, frame::frame_alignment), "");
 
-  // All the frames have been thawed so we know they don't hold any monitors
-  assert(thread->held_monitor_count() == 0, "Must be");
+  // All or part of the frames have been thawed so we know they don't hold any monitors except JNI monitors.
+  assert(thread->held_monitor_count() == thread->jni_monitor_count(), "Must be");
 
 #ifdef ASSERT
   intptr_t* sp0 = sp;
diff --git a/src/hotspot/share/runtime/flags/jvmFlag.cpp b/src/hotspot/share/runtime/flags/jvmFlag.cpp
index 1917cd4b198..c465a942e5c 100644
--- a/src/hotspot/share/runtime/flags/jvmFlag.cpp
+++ b/src/hotspot/share/runtime/flags/jvmFlag.cpp
@@ -31,6 +31,7 @@
 #include "runtime/flags/jvmFlagAccess.hpp"
 #include "runtime/flags/jvmFlagLookup.hpp"
 #include "runtime/globals_extension.hpp"
+#include "utilities/bitMap.hpp"
 #include "utilities/defaultStream.hpp"
 #include "utilities/stringUtils.hpp"
 
@@ -692,7 +693,7 @@ void JVMFlag::printFlags(outputStream* out, bool withComments, bool printRanges,
   //       called as part of error reporting, so handle native OOMs gracefully.
 
   // The last entry is the null entry.
-  const size_t length = JVMFlag::numFlags - 1;
+  constexpr size_t length = (sizeof(flagTable) / sizeof(JVMFlag)) - 1;
 
   // Print
   if (!printRanges) {
@@ -701,26 +702,26 @@ void JVMFlag::printFlags(outputStream* out, bool withComments, bool printRanges,
     out->print_cr("[Global flags ranges]");
   }
 
-  // Sort
-  JVMFlag** array = NEW_C_HEAP_ARRAY_RETURN_NULL(JVMFlag*, length, mtArguments);
-  if (array != nullptr) {
-    for (size_t i = 0; i < length; i++) {
-      array[i] = &flagTable[i];
-    }
-    qsort(array, length, sizeof(JVMFlag*), compare_flags);
-
+  BitMap::bm_word_t iteratorArray[BitMap::calc_size_in_words(length)];
+  BitMapView iteratorMarkers(iteratorArray, length);
+  iteratorMarkers.clear_range(0, length);
+  // Print the flag with best sort value, then mark it.
+  for (size_t j = 0; j < length; j++) {
+    JVMFlag* bestFlag = nullptr;
+    size_t bestFlagIndex = 0;
     for (size_t i = 0; i < length; i++) {
-      if (array[i]->is_unlocked() && !(skipDefaults && array[i]->is_default())) {
-        array[i]->print_on(out, withComments, printRanges);
+      const bool skip = (skipDefaults && flagTable[i].is_default());
+      const bool visited = iteratorMarkers.at(i);
+      if (!visited && flagTable[i].is_unlocked() && !skip) {
+        if ((bestFlag == nullptr) || (strcmp(bestFlag->name(), flagTable[i].name()) > 0)) {
+          bestFlag = &flagTable[i];
+          bestFlagIndex = i;
+        }
       }
     }
-    FREE_C_HEAP_ARRAY(JVMFlag*, array);
-  } else {
-    // OOM? Print unsorted.
-    for (size_t i = 0; i < length; i++) {
-      if (flagTable[i].is_unlocked() && !(skipDefaults && flagTable[i].is_default())) {
-        flagTable[i].print_on(out, withComments, printRanges);
-      }
+    if (bestFlag != nullptr) {
+      bestFlag->print_on(out, withComments, printRanges);
+      iteratorMarkers.at_put(bestFlagIndex, true);
     }
   }
 }
diff --git a/src/hotspot/share/runtime/globals.hpp b/src/hotspot/share/runtime/globals.hpp
index 7a7a3769ac9..562549f247e 100644
--- a/src/hotspot/share/runtime/globals.hpp
+++ b/src/hotspot/share/runtime/globals.hpp
@@ -795,10 +795,6 @@ const int ObjectAlignmentInBytes = 8;
           "but not all -Xrun libraries may support the state of the VM "    \
           "at this time")                                                   \
                                                                             \
-  product(bool, PreserveAllAnnotations, false,                              \
-          "(Deprecated) Preserve RuntimeInvisibleAnnotations as well "      \
-          "as RuntimeVisibleAnnotations")                                   \
-                                                                            \
   develop(uintx, PreallocatedOutOfMemoryErrorCount, 4,                      \
           "Number of OutOfMemoryErrors preallocated with backtrace")        \
                                                                             \
diff --git a/src/hotspot/share/runtime/javaThread.cpp b/src/hotspot/share/runtime/javaThread.cpp
index a3eef07ba0a..b69ab708afa 100644
--- a/src/hotspot/share/runtime/javaThread.cpp
+++ b/src/hotspot/share/runtime/javaThread.cpp
@@ -470,8 +470,8 @@ JavaThread::JavaThread(MEMFLAGS flags) :
 #endif // INCLUDE_JVMCI
 
   _exception_oop(oop()),
-  _exception_pc(0),
-  _exception_handler_pc(0),
+  _exception_pc(nullptr),
+  _exception_handler_pc(nullptr),
   _is_method_handle_return(0),
 
   _jni_active_critical(0),
@@ -483,7 +483,7 @@ JavaThread::JavaThread(MEMFLAGS flags) :
   _frames_to_pop_failed_realloc(0),
 
   _cont_entry(nullptr),
-  _cont_fastpath(0),
+  _cont_fastpath(nullptr),
   _cont_fastpath_thread_state(1),
   _held_monitor_count(0),
   _jni_monitor_count(0),
diff --git a/src/hotspot/share/runtime/synchronizer.cpp b/src/hotspot/share/runtime/synchronizer.cpp
index 047f6703b54..2d45163d0f4 100644
--- a/src/hotspot/share/runtime/synchronizer.cpp
+++ b/src/hotspot/share/runtime/synchronizer.cpp
@@ -2074,7 +2074,7 @@ void ObjectSynchronizer::chk_in_use_entry(ObjectMonitor* n, outputStream* out,
 void ObjectSynchronizer::log_in_use_monitor_details(outputStream* out, bool log_all) {
   if (_in_use_list.count() > 0) {
     stringStream ss;
-    out->print_cr("In-use monitor info:");
+    out->print_cr("In-use monitor info%s:", log_all ? "" : " (eliding idle monitors)");
     out->print_cr("(B -> is_busy, H -> has hash code, L -> lock status)");
     out->print_cr("%18s  %s  %18s  %18s",
                   "monitor", "BHL", "object", "object type");
diff --git a/src/hotspot/share/runtime/vframeArray.cpp b/src/hotspot/share/runtime/vframeArray.cpp
index d3bbbc28399..1b26abf7402 100644
--- a/src/hotspot/share/runtime/vframeArray.cpp
+++ b/src/hotspot/share/runtime/vframeArray.cpp
@@ -321,7 +321,7 @@ void vframeArrayElement::unpack_on_stack(int caller_actual_parameters,
            "should be held, after move_to");
   }
   if (ProfileInterpreter) {
-    iframe()->interpreter_frame_set_mdp(0); // clear out the mdp.
+    iframe()->interpreter_frame_set_mdp(nullptr); // clear out the mdp.
   }
   iframe()->interpreter_frame_set_bcp(bcp);
   if (ProfileInterpreter) {
diff --git a/src/hotspot/share/services/diagnosticArgument.cpp b/src/hotspot/share/services/diagnosticArgument.cpp
index 94f2d3e1eb1..5fd565a605a 100644
--- a/src/hotspot/share/services/diagnosticArgument.cpp
+++ b/src/hotspot/share/services/diagnosticArgument.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -189,9 +189,18 @@ template <> void DCmdArgument<char*>::parse_value(const char* str,
     destroy_value();
   } else {
     // Use realloc as we may have a default set.
-    _value = REALLOC_C_HEAP_ARRAY(char, _value, len + 1, mtInternal);
-    int n = os::snprintf(_value, len + 1, "%.*s", (int)len, str);
-    assert((size_t)n <= len, "Unexpected number of characters in string");
+    if (strcmp(type(), "FILE") == 0) {
+      _value = REALLOC_C_HEAP_ARRAY(char, _value, JVM_MAXPATHLEN, mtInternal);
+      if (!Arguments::copy_expand_pid(str, len, _value, JVM_MAXPATHLEN)) {
+        stringStream error_msg;
+        error_msg.print("File path invalid or too long: %s", str);
+        THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), error_msg.base());
+      }
+    } else {
+      _value = REALLOC_C_HEAP_ARRAY(char, _value, len + 1, mtInternal);
+      int n = os::snprintf(_value, len + 1, "%.*s", (int)len, str);
+      assert((size_t)n <= len, "Unexpected number of characters in string");
+    }
   }
 }
 
diff --git a/src/hotspot/share/services/diagnosticArgument.hpp b/src/hotspot/share/services/diagnosticArgument.hpp
index c9683ce4a21..1451ea34f86 100644
--- a/src/hotspot/share/services/diagnosticArgument.hpp
+++ b/src/hotspot/share/services/diagnosticArgument.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,6 +27,7 @@
 
 #include "classfile/vmSymbols.hpp"
 #include "memory/allocation.hpp"
+#include "runtime/arguments.hpp"
 #include "runtime/javaThread.hpp"
 #include "runtime/os.hpp"
 #include "utilities/exceptions.hpp"
diff --git a/src/hotspot/share/services/diagnosticCommand.cpp b/src/hotspot/share/services/diagnosticCommand.cpp
index e6328e95abd..7a2c0838146 100644
--- a/src/hotspot/share/services/diagnosticCommand.cpp
+++ b/src/hotspot/share/services/diagnosticCommand.cpp
@@ -473,7 +473,7 @@ void FinalizerInfoDCmd::execute(DCmdSource source, TRAPS) {
 #if INCLUDE_SERVICES // Heap dumping/inspection supported
 HeapDumpDCmd::HeapDumpDCmd(outputStream* output, bool heap) :
                            DCmdWithParser(output, heap),
-  _filename("filename","Name of the dump file", "STRING",true),
+  _filename("filename","Name of the dump file", "FILE",true),
   _all("-all", "Dump all objects, including unreachable objects",
        "BOOLEAN", false, "false"),
   _gzip("-gz", "If specified, the heap dump is written in gzipped format "
@@ -852,20 +852,15 @@ void CodeCacheDCmd::execute(DCmdSource source, TRAPS) {
 }
 
 #ifdef LINUX
-#define DEFAULT_PERFMAP_FILENAME "/tmp/perf-<pid>.map"
-
 PerfMapDCmd::PerfMapDCmd(outputStream* output, bool heap) :
              DCmdWithParser(output, heap),
-  _filename("filename", "Name of the map file", "STRING", false, DEFAULT_PERFMAP_FILENAME)
+  _filename("filename", "Name of the map file", "FILE", false, DEFAULT_PERFMAP_FILENAME)
 {
   _dcmdparser.add_dcmd_argument(&_filename);
 }
 
 void PerfMapDCmd::execute(DCmdSource source, TRAPS) {
-  // The check for _filename.is_set() is because we don't want to use
-  // DEFAULT_PERFMAP_FILENAME, since it is meant as a description
-  // of the default, not the actual default.
-  CodeCache::write_perf_map(_filename.is_set() ? _filename.value() : nullptr, output());
+  CodeCache::write_perf_map(_filename.value(), output());
 }
 #endif // LINUX
 
@@ -997,12 +992,12 @@ void ClassesDCmd::execute(DCmdSource source, TRAPS) {
 }
 
 #if INCLUDE_CDS
-#define DEFAULT_CDS_ARCHIVE_FILENAME "java_pid<pid>_<subcmd>.jsa"
+#define DEFAULT_CDS_ARCHIVE_FILENAME "java_pid%p_<subcmd>.jsa"
 
 DumpSharedArchiveDCmd::DumpSharedArchiveDCmd(outputStream* output, bool heap) :
                                      DCmdWithParser(output, heap),
   _suboption("subcmd", "static_dump | dynamic_dump", "STRING", true),
-  _filename("filename", "Name of shared archive to be dumped", "STRING", false,
+  _filename("filename", "Name of shared archive to be dumped", "FILE", false,
             DEFAULT_CDS_ARCHIVE_FILENAME)
 {
   _dcmdparser.add_dcmd_argument(&_suboption);
@@ -1040,7 +1035,7 @@ void DumpSharedArchiveDCmd::execute(DCmdSource source, TRAPS) {
   // call CDS.dumpSharedArchive
   Handle fileh;
   if (file != nullptr) {
-    fileh =  java_lang_String::create_from_str(_filename.value(), CHECK);
+    fileh = java_lang_String::create_from_str(file, CHECK);
   }
   Symbol* cds_name  = vmSymbols::jdk_internal_misc_CDS();
   Klass*  cds_klass = SystemDictionary::resolve_or_fail(cds_name, true /*throw error*/,  CHECK);
@@ -1105,7 +1100,7 @@ ThreadDumpToFileDCmd::ThreadDumpToFileDCmd(outputStream* output, bool heap) :
                                            DCmdWithParser(output, heap),
   _overwrite("-overwrite", "May overwrite existing file", "BOOLEAN", false, "false"),
   _format("-format", "Output format (\"plain\" or \"json\")", "STRING", false, "plain"),
-  _filepath("filepath", "The file path to the output file", "STRING", true) {
+  _filepath("filepath", "The file path to the output file", "FILE", true) {
   _dcmdparser.add_dcmd_option(&_overwrite);
   _dcmdparser.add_dcmd_option(&_format);
   _dcmdparser.add_dcmd_argument(&_filepath);
@@ -1186,23 +1181,16 @@ void SystemMapDCmd::execute(DCmdSource source, TRAPS) {
   MemMapPrinter::print_all_mappings(output());
 }
 
-static constexpr char default_filename[] = "vm_memory_map_<pid>.txt";
+static constexpr char default_filename[] = "vm_memory_map_%p.txt";
 
 SystemDumpMapDCmd::SystemDumpMapDCmd(outputStream* output, bool heap) :
   DCmdWithParser(output, heap),
-  _filename("-F", "file path", "STRING", false, default_filename) {
+  _filename("-F", "file path", "FILE", false, default_filename) {
   _dcmdparser.add_dcmd_option(&_filename);
 }
 
 void SystemDumpMapDCmd::execute(DCmdSource source, TRAPS) {
-  stringStream defaultname;
-  const char* name = nullptr;
-  if (_filename.is_set()) {
-    name = _filename.value();
-  } else {
-    defaultname.print("vm_memory_map_%d.txt", os::current_process_id());
-    name = defaultname.base();
-  }
+  const char* name = _filename.value();
   fileStream fs(name);
   if (fs.is_open()) {
     if (!MemTracker::enabled()) {
diff --git a/src/hotspot/share/services/diagnosticFramework.hpp b/src/hotspot/share/services/diagnosticFramework.hpp
index e8881c23646..357482ec5a1 100644
--- a/src/hotspot/share/services/diagnosticFramework.hpp
+++ b/src/hotspot/share/services/diagnosticFramework.hpp
@@ -67,7 +67,7 @@ class CmdLine : public StackObj {
   const char* cmd_addr() const    { return _cmd; }
   size_t cmd_len() const          { return _cmd_len; }
   bool is_empty() const           { return _cmd_len == 0; }
-  bool is_executable() const      { return is_empty() || _cmd[0] != '#'; }
+  bool is_executable() const      { return !is_empty() && _cmd[0] != '#'; }
   bool is_stop() const            { return !is_empty() && strncmp("stop", _cmd, _cmd_len) == 0; }
 };
 
diff --git a/src/hotspot/share/utilities/bitMap.cpp b/src/hotspot/share/utilities/bitMap.cpp
index 9bd5c8e0006..a0780707091 100644
--- a/src/hotspot/share/utilities/bitMap.cpp
+++ b/src/hotspot/share/utilities/bitMap.cpp
@@ -197,11 +197,6 @@ bm_word_t* CHeapBitMap::reallocate(bm_word_t* map, size_t old_size_in_words, siz
 }
 
 #ifdef ASSERT
-void BitMap::verify_size(idx_t size_in_bits) {
-  assert(size_in_bits <= max_size_in_bits(),
-         "out of bounds: " SIZE_FORMAT, size_in_bits);
-}
-
 void BitMap::verify_index(idx_t bit) const {
   assert(bit < _size,
          "BitMap index out of bounds: " SIZE_FORMAT " >= " SIZE_FORMAT,
diff --git a/src/hotspot/share/utilities/bitMap.hpp b/src/hotspot/share/utilities/bitMap.hpp
index 0d592de7cd0..5db12badbc9 100644
--- a/src/hotspot/share/utilities/bitMap.hpp
+++ b/src/hotspot/share/utilities/bitMap.hpp
@@ -67,16 +67,16 @@ class BitMap {
  protected:
   // The maximum allowable size of a bitmap, in words or bits.
   // Limit max_size_in_bits so aligning up to a word boundary never overflows.
-  static idx_t max_size_in_words() { return raw_to_words_align_down(~idx_t(0)); }
-  static idx_t max_size_in_bits() { return max_size_in_words() * BitsPerWord; }
+  constexpr static idx_t max_size_in_words() { return raw_to_words_align_down(~idx_t(0)); }
+  constexpr static idx_t max_size_in_bits() { return max_size_in_words() * BitsPerWord; }
 
   // Assumes relevant validity checking for bit has already been done.
-  static idx_t raw_to_words_align_up(idx_t bit) {
+  constexpr static idx_t raw_to_words_align_up(idx_t bit) {
     return raw_to_words_align_down(bit + (BitsPerWord - 1));
   }
 
   // Assumes relevant validity checking for bit has already been done.
-  static idx_t raw_to_words_align_down(idx_t bit) {
+  constexpr static idx_t raw_to_words_align_down(idx_t bit) {
     return bit >> LogBitsPerWord;
   }
 
@@ -195,7 +195,7 @@ class BitMap {
   void pretouch();
 
   // Accessing
-  static idx_t calc_size_in_words(size_t size_in_bits) {
+  constexpr static idx_t calc_size_in_words(size_t size_in_bits) {
     verify_size(size_in_bits);
     return raw_to_words_align_up(size_in_bits);
   }
@@ -257,7 +257,13 @@ class BitMap {
   // Verification.
 
   // Verify size_in_bits does not exceed max_size_in_bits().
-  static void verify_size(idx_t size_in_bits) NOT_DEBUG_RETURN;
+  constexpr static void verify_size(idx_t size_in_bits) {
+#ifdef ASSERT
+    assert(size_in_bits <= max_size_in_bits(),
+           "out of bounds: " SIZE_FORMAT, size_in_bits);
+#endif
+  }
+
   // Verify bit is less than size().
   void verify_index(idx_t bit) const NOT_DEBUG_RETURN;
   // Verify bit is not greater than size().
diff --git a/src/hotspot/share/utilities/exceptions.cpp b/src/hotspot/share/utilities/exceptions.cpp
index c8f458dfa31..034444839ab 100644
--- a/src/hotspot/share/utilities/exceptions.cpp
+++ b/src/hotspot/share/utilities/exceptions.cpp
@@ -43,6 +43,7 @@
 #include "runtime/atomic.hpp"
 #include "utilities/events.hpp"
 #include "utilities/exceptions.hpp"
+#include "utilities/utf8.hpp"
 
 // Limit exception message components to 64K (the same max as Symbols)
 #define MAX_LEN 65535
@@ -262,8 +263,32 @@ void Exceptions::fthrow(JavaThread* thread, const char* file, int line, Symbol*
   va_list ap;
   va_start(ap, format);
   char msg[max_msg_size];
-  os::vsnprintf(msg, max_msg_size, format, ap);
+  int ret = os::vsnprintf(msg, max_msg_size, format, ap);
   va_end(ap);
+
+  // If ret == -1 then either there was a format conversion error, or the required buffer size
+  // exceeds INT_MAX and so couldn't be returned (undocumented behaviour of vsnprintf). Depending
+  // on the platform the buffer may be filled to its capacity (Linux), filled to the conversion
+  // that encountered the overflow (macOS), or is empty (Windows), so it is possible we
+  // have a truncated UTF-8 sequence. Similarly, if the buffer was too small and ret >= max_msg_size
+  // we may also have a truncated UTF-8 sequence. In such cases we need to fix the buffer so the UTF-8
+  // sequence is valid.
+  if (ret == -1 || ret >= max_msg_size) {
+    int len = (int) strlen(msg);
+    if (len > 0) {
+      // Truncation will only happen if the buffer was filled by vsnprintf,
+      // otherwise vsnprintf already terminated filling it at a well-defined point.
+      // But as this is not a clearly specified area we will perform our own UTF8
+      // truncation anyway - though for those well-defined termination points it
+      // will be a no-op.
+      UTF8::truncate_to_legal_utf8((unsigned char*)msg, len + 1);
+    }
+  }
+  // UTF8::is_legal_utf8 should actually be called is_legal_utf8_class_name as the final
+  // parameter controls a check for a specific character appearing in the "name", which is only
+  // allowed for classfile versions <= 47. We pass `true` so that we allow such strings as this code
+  // know nothing about the actual string content.
+  assert(UTF8::is_legal_utf8((const unsigned char*)msg, (int)strlen(msg), true), "must be");
   _throw_msg(thread, file, line, h_name, msg);
 }
 
diff --git a/src/hotspot/share/utilities/globalDefinitions.hpp b/src/hotspot/share/utilities/globalDefinitions.hpp
index 74817a35e77..b7be6dc04bf 100644
--- a/src/hotspot/share/utilities/globalDefinitions.hpp
+++ b/src/hotspot/share/utilities/globalDefinitions.hpp
@@ -222,9 +222,9 @@ FORBID_C_FUNCTION(void* reallocf(void *ptr, size_t size), "don't use");
 const int LogBytesPerShort   = 1;
 const int LogBytesPerInt     = 2;
 #ifdef _LP64
-const int LogBytesPerWord    = 3;
+constexpr int LogBytesPerWord    = 3;
 #else
-const int LogBytesPerWord    = 2;
+constexpr int LogBytesPerWord    = 2;
 #endif
 const int LogBytesPerLong    = 3;
 
@@ -233,16 +233,16 @@ const int BytesPerInt        = 1 << LogBytesPerInt;
 const int BytesPerWord       = 1 << LogBytesPerWord;
 const int BytesPerLong       = 1 << LogBytesPerLong;
 
-const int LogBitsPerByte     = 3;
+constexpr int LogBitsPerByte     = 3;
 const int LogBitsPerShort    = LogBitsPerByte + LogBytesPerShort;
 const int LogBitsPerInt      = LogBitsPerByte + LogBytesPerInt;
-const int LogBitsPerWord     = LogBitsPerByte + LogBytesPerWord;
+constexpr int LogBitsPerWord     = LogBitsPerByte + LogBytesPerWord;
 const int LogBitsPerLong     = LogBitsPerByte + LogBytesPerLong;
 
 const int BitsPerByte        = 1 << LogBitsPerByte;
 const int BitsPerShort       = 1 << LogBitsPerShort;
 const int BitsPerInt         = 1 << LogBitsPerInt;
-const int BitsPerWord        = 1 << LogBitsPerWord;
+constexpr int BitsPerWord        = 1 << LogBitsPerWord;
 const int BitsPerLong        = 1 << LogBitsPerLong;
 
 const int WordAlignmentMask  = (1 << LogBytesPerWord) - 1;
diff --git a/src/hotspot/share/utilities/utf8.cpp b/src/hotspot/share/utilities/utf8.cpp
index 6fd877120df..47cbb04da4b 100644
--- a/src/hotspot/share/utilities/utf8.cpp
+++ b/src/hotspot/share/utilities/utf8.cpp
@@ -392,6 +392,69 @@ bool UTF8::is_legal_utf8(const unsigned char* buffer, int length,
   return true;
 }
 
+// Return true if `b` could be the starting byte of an encoded 2,3 or 6
+// byte sequence.
+static bool is_starting_byte(unsigned char b) {
+  return b >= 0xC0 && b <= 0xEF;
+}
+
+// Takes an incoming buffer that was valid UTF-8, but which has been truncated such that
+// the last encoding may be partial, and returns the same buffer with a NUL-terminator
+// inserted such that any partial encoding has gone.
+// Note: if the incoming buffer is already valid then we may still drop the last encoding.
+// To avoid that the caller can choose to check for validity first.
+// The incoming buffer is still expected to be NUL-terminated.
+// The incoming buffer is expected to be a realistic size - we assert if it is too small.
+void UTF8::truncate_to_legal_utf8(unsigned char* buffer, int length) {
+  assert(length > 5, "invalid length");
+  assert(buffer[length - 1] == '\0', "Buffer should be NUL-terminated");
+
+  if (buffer[length - 2] < 128) {  // valid "ascii" - common case
+    return;
+  }
+
+  // Modified UTF-8 encodes characters in sequences of 1, 2, 3 or 6 bytes.
+  // The last byte is invalid if it is:
+  // - the 1st byte of a 2, 3 or 6 byte sequence
+  //     0b110xxxxx
+  //     0b1110xxxx
+  //     0b11101101
+  // - the 2nd byte of a 3 or 6 byte sequence
+  //     0b10xxxxxx
+  //     0b1010xxxx
+  // - the 3rd, 4th or 5th byte of a 6 byte sequence
+  //     0b10xxxxxx
+  //     0b11101101
+  //     0b1011xxxx
+  //
+  // Rather than checking all possible situations we simplify things noting that as we have already
+  // got a truncated string, then dropping one more character is not significant. So we work from the
+  // end of the buffer looking for the first byte that can be the starting byte of a UTF-8 encoded sequence,
+  // then we insert NUL at that location to terminate the buffer. There is an added complexity with 6 byte
+  // encodings as the first and fourth bytes are the same and overlap with the 3 byte encoding.
+
+  for (int index = length - 2; index > 0; index--) {
+    if (is_starting_byte(buffer[index])) {
+      if (buffer[index] == 0xED) {
+        // Could be first byte of 3 or 6, or fourth byte of 6.
+        // If fourth the previous three bytes will encode a high
+        // surrogate value in the range EDA080 to EDAFBF. We only
+        // need to check for EDA to establish this as the "missing"
+        // values in EDAxxx would not be valid 3 byte encodings.
+        if ((index - 3) >= 0 &&
+            (buffer[index - 3] == 0xED) &&
+            ((buffer[index - 2] & 0xF0) == 0xA0)) {
+          assert(buffer[index - 1] >= 0x80 && buffer[index - 1] <= 0xBF, "sanity check");
+          // It was fourth byte so truncate 3 bytes earlier
+          index -= 3;
+        }
+      }
+      buffer[index] = '\0';
+      break;
+    }
+  }
+}
+
 //-------------------------------------------------------------------------------------
 
 bool UNICODE::is_latin1(jchar c) {
diff --git a/src/hotspot/share/utilities/utf8.hpp b/src/hotspot/share/utilities/utf8.hpp
index 80346f7da7d..9a18dd0ff93 100644
--- a/src/hotspot/share/utilities/utf8.hpp
+++ b/src/hotspot/share/utilities/utf8.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -88,6 +88,7 @@ class UTF8 : AllStatic {
 
   static bool   is_legal_utf8(const unsigned char* buffer, int length,
                               bool version_leq_47);
+  static void   truncate_to_legal_utf8(unsigned char* buffer, int length);
 };
 
 
diff --git a/src/java.base/linux/native/libnio/ch/FileDispatcherImpl.c b/src/java.base/linux/native/libnio/ch/FileDispatcherImpl.c
index 02d3c57f1f3..efbd0ca5684 100644
--- a/src/java.base/linux/native/libnio/ch/FileDispatcherImpl.c
+++ b/src/java.base/linux/native/libnio/ch/FileDispatcherImpl.c
@@ -114,7 +114,7 @@ Java_sun_nio_ch_FileDispatcherImpl_transferTo0(JNIEnv *env, jobject this,
             return n;
     }
 
-    n = sendfile64(dstFD, srcFD, &offset, (size_t)count);
+    n = sendfile(dstFD, srcFD, &offset, (size_t)count);
     if (n < 0) {
         if (errno == EAGAIN)
             return IOS_UNAVAILABLE;
diff --git a/src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c b/src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c
index 95f78ffa135..c90e99dda07 100644
--- a/src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c
+++ b/src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c
@@ -211,7 +211,7 @@ Java_sun_nio_fs_LinuxNativeDispatcher_directCopy0
     }
 
     do {
-        RESTARTABLE(sendfile64(dst, src, NULL, count), bytes_sent);
+        RESTARTABLE(sendfile(dst, src, NULL, count), bytes_sent);
         if (bytes_sent < 0) {
             if (errno == EAGAIN)
                 return IOS_UNAVAILABLE;
diff --git a/src/java.base/share/classes/java/lang/AbstractStringBuilder.java b/src/java.base/share/classes/java/lang/AbstractStringBuilder.java
index 7e5056a539b..e0c3aa19f54 100644
--- a/src/java.base/share/classes/java/lang/AbstractStringBuilder.java
+++ b/src/java.base/share/classes/java/lang/AbstractStringBuilder.java
@@ -27,6 +27,7 @@
 
 import jdk.internal.math.DoubleToDecimal;
 import jdk.internal.math.FloatToDecimal;
+import jdk.internal.util.DecimalDigits;
 
 import java.io.IOException;
 import java.nio.CharBuffer;
@@ -836,7 +837,7 @@ public AbstractStringBuilder append(char c) {
      */
     public AbstractStringBuilder append(int i) {
         int count = this.count;
-        int spaceNeeded = count + Integer.stringSize(i);
+        int spaceNeeded = count + DecimalDigits.stringSize(i);
         ensureCapacityInternal(spaceNeeded);
         if (isLatin1()) {
             StringLatin1.getChars(i, spaceNeeded, value);
@@ -861,7 +862,7 @@ public AbstractStringBuilder append(int i) {
      */
     public AbstractStringBuilder append(long l) {
         int count = this.count;
-        int spaceNeeded = count + Long.stringSize(l);
+        int spaceNeeded = count + DecimalDigits.stringSize(l);
         ensureCapacityInternal(spaceNeeded);
         if (isLatin1()) {
             StringLatin1.getChars(l, spaceNeeded, value);
diff --git a/src/java.base/share/classes/java/lang/Integer.java b/src/java.base/share/classes/java/lang/Integer.java
index 1c5b3c414ba..7a65046181f 100644
--- a/src/java.base/share/classes/java/lang/Integer.java
+++ b/src/java.base/share/classes/java/lang/Integer.java
@@ -27,6 +27,7 @@
 
 import jdk.internal.misc.CDS;
 import jdk.internal.misc.VM;
+import jdk.internal.util.DecimalDigits;
 import jdk.internal.vm.annotation.ForceInline;
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 import jdk.internal.vm.annotation.Stable;
@@ -427,7 +428,7 @@ private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int l
      */
     @IntrinsicCandidate
     public static String toString(int i) {
-        int size = stringSize(i);
+        int size = DecimalDigits.stringSize(i);
         if (COMPACT_STRINGS) {
             byte[] buf = new byte[size];
             StringLatin1.getChars(i, size, buf);
@@ -457,32 +458,6 @@ public static String toUnsignedString(int i) {
         return Long.toString(toUnsignedLong(i));
     }
 
-    /**
-     * Returns the string representation size for a given int value.
-     *
-     * @param x int value
-     * @return string size
-     *
-     * @implNote There are other ways to compute this: e.g. binary search,
-     * but values are biased heavily towards zero, and therefore linear search
-     * wins. The iteration results are also routinely inlined in the generated
-     * code after loop unrolling.
-     */
-    static int stringSize(int x) {
-        int d = 1;
-        if (x >= 0) {
-            d = 0;
-            x = -x;
-        }
-        int p = -10;
-        for (int i = 1; i < 10; i++) {
-            if (x > p)
-                return i + d;
-            p = 10 * p;
-        }
-        return 10 + d;
-    }
-
     /**
      * Parses the string argument as a signed integer in the radix
      * specified by the second argument. The characters in the string
diff --git a/src/java.base/share/classes/java/lang/Long.java b/src/java.base/share/classes/java/lang/Long.java
index 70bd2d62add..ee9533b29eb 100644
--- a/src/java.base/share/classes/java/lang/Long.java
+++ b/src/java.base/share/classes/java/lang/Long.java
@@ -34,6 +34,7 @@
 import java.util.Optional;
 
 import jdk.internal.misc.CDS;
+import jdk.internal.util.DecimalDigits;
 import jdk.internal.vm.annotation.ForceInline;
 import jdk.internal.vm.annotation.IntrinsicCandidate;
 import jdk.internal.vm.annotation.Stable;
@@ -457,7 +458,7 @@ private static void formatUnsignedLong0UTF16(long val, int shift, byte[] buf, in
      * @return  a string representation of the argument in base&nbsp;10.
      */
     public static String toString(long i) {
-        int size = stringSize(i);
+        int size = DecimalDigits.stringSize(i);
         if (COMPACT_STRINGS) {
             byte[] buf = new byte[size];
             StringLatin1.getChars(i, size, buf);
@@ -487,32 +488,6 @@ public static String toUnsignedString(long i) {
         return toUnsignedString(i, 10);
     }
 
-    /**
-     * Returns the string representation size for a given long value.
-     *
-     * @param x long value
-     * @return string size
-     *
-     * @implNote There are other ways to compute this: e.g. binary search,
-     * but values are biased heavily towards zero, and therefore linear search
-     * wins. The iteration results are also routinely inlined in the generated
-     * code after loop unrolling.
-     */
-    static int stringSize(long x) {
-        int d = 1;
-        if (x >= 0) {
-            d = 0;
-            x = -x;
-        }
-        long p = -10;
-        for (int i = 1; i < 19; i++) {
-            if (x > p)
-                return i + d;
-            p = 10 * p;
-        }
-        return 19 + d;
-    }
-
     /**
      * Parses the string argument as a signed {@code long} in the
      * radix specified by the second argument. The characters in the
diff --git a/src/java.base/share/classes/java/lang/StringConcatHelper.java b/src/java.base/share/classes/java/lang/StringConcatHelper.java
index bcd9c65890f..486e115369e 100644
--- a/src/java.base/share/classes/java/lang/StringConcatHelper.java
+++ b/src/java.base/share/classes/java/lang/StringConcatHelper.java
@@ -26,6 +26,7 @@
 package java.lang;
 
 import jdk.internal.misc.Unsafe;
+import jdk.internal.util.DecimalDigits;
 import jdk.internal.vm.annotation.ForceInline;
 
 import java.lang.invoke.MethodHandle;
@@ -96,7 +97,7 @@ static long mix(long lengthCoder, char value) {
      * @return            new length and coder
      */
     static long mix(long lengthCoder, int value) {
-        return checkOverflow(lengthCoder + Integer.stringSize(value));
+        return checkOverflow(lengthCoder + DecimalDigits.stringSize(value));
     }
 
     /**
@@ -107,7 +108,7 @@ static long mix(long lengthCoder, int value) {
      * @return            new length and coder
      */
     static long mix(long lengthCoder, long value) {
-        return checkOverflow(lengthCoder + Long.stringSize(value));
+        return checkOverflow(lengthCoder + DecimalDigits.stringSize(value));
     }
 
     /**
@@ -184,7 +185,7 @@ static long prepend(long indexCoder, byte[] buf, boolean value, String prefix) {
      * @param indexCoder final char index in the buffer, along with coder packed
      *                   into higher bits.
      * @param buf        buffer to append to
-     * @param value      boolean value to encode
+     * @param value      char value to encode
      * @param prefix     a constant to prepend before value
      * @return           updated index (coder value retained)
      */
@@ -210,7 +211,7 @@ static long prepend(long indexCoder, byte[] buf, char value, String prefix) {
      * @param indexCoder final char index in the buffer, along with coder packed
      *                   into higher bits.
      * @param buf        buffer to append to
-     * @param value      boolean value to encode
+     * @param value      int value to encode
      * @param prefix     a constant to prepend before value
      * @return           updated index (coder value retained)
      */
@@ -236,7 +237,7 @@ static long prepend(long indexCoder, byte[] buf, int value, String prefix) {
      * @param indexCoder final char index in the buffer, along with coder packed
      *                   into higher bits.
      * @param buf        buffer to append to
-     * @param value      boolean value to encode
+     * @param value      long value to encode
      * @param prefix     a constant to prepend before value
      * @return           updated index (coder value retained)
      */
diff --git a/src/java.base/share/classes/java/lang/System.java b/src/java.base/share/classes/java/lang/System.java
index 3157a200278..0947da8ded7 100644
--- a/src/java.base/share/classes/java/lang/System.java
+++ b/src/java.base/share/classes/java/lang/System.java
@@ -65,7 +65,6 @@
 import java.util.ResourceBundle;
 import java.util.Set;
 import java.util.WeakHashMap;
-import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Stream;
@@ -2264,6 +2263,7 @@ private static class Out extends FileOutputStream {
             super(fd);
         }
 
+        @Override
         public void write(int b) throws IOException {
             boolean attempted = Blocker.begin();
             try {
@@ -2623,10 +2623,6 @@ public long stringConcatMix(long lengthCoder, char value) {
                 return StringConcatHelper.mix(lengthCoder, value);
             }
 
-            public int stringSize(long i) {
-                return Long.stringSize(i);
-            }
-
             public int getCharsLatin1(long i, int index, byte[] buf) {
                 return StringLatin1.getChars(i, index, buf);
             }
@@ -2677,14 +2673,6 @@ public Thread currentCarrierThread() {
                 return Thread.currentCarrierThread();
             }
 
-            public <V> V executeOnCarrierThread(Callable<V> task) throws Exception {
-                if (Thread.currentThread() instanceof VirtualThread vthread) {
-                    return vthread.executeOnCarrierThread(task);
-                } else {
-                    return task.call();
-                }
-            }
-
             public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
                 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
             }
diff --git a/src/java.base/share/classes/java/lang/VirtualThread.java b/src/java.base/share/classes/java/lang/VirtualThread.java
index cf2fed3bf5d..da05e77f12b 100644
--- a/src/java.base/share/classes/java/lang/VirtualThread.java
+++ b/src/java.base/share/classes/java/lang/VirtualThread.java
@@ -40,6 +40,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
 import jdk.internal.event.VirtualThreadEndEvent;
 import jdk.internal.event.VirtualThreadPinnedEvent;
 import jdk.internal.event.VirtualThreadStartEvent;
@@ -62,14 +63,13 @@
 import static java.util.concurrent.TimeUnit.*;
 
 /**
- * A thread that is scheduled by the Java virtual machine rather than the operating
- * system.
+ * A thread that is scheduled by the Java virtual machine rather than the operating system.
  */
 final class VirtualThread extends BaseVirtualThread {
     private static final Unsafe U = Unsafe.getUnsafe();
     private static final ContinuationScope VTHREAD_SCOPE = new ContinuationScope("VirtualThreads");
     private static final ForkJoinPool DEFAULT_SCHEDULER = createDefaultScheduler();
-    private static final ScheduledExecutorService UNPARKER = createDelayedTaskScheduler();
+    private static final ScheduledExecutorService[] DELAYED_TASK_SCHEDULERS = createDelayedTaskSchedulers();
     private static final int TRACE_PINNING_MODE = tracePinningMode();
 
     private static final long STATE = U.objectFieldOffset(VirtualThread.class, "state");
@@ -217,7 +217,7 @@ public void run() {
      * on the current thread before the task runs or continues. It unmounts when the
      * task completes or yields.
      */
-    @ChangesCurrentThread
+    @ChangesCurrentThread // allow mount/unmount to be inlined
     private void runContinuation() {
         // the carrier must be a platform thread
         if (Thread.currentThread().isVirtual()) {
@@ -257,42 +257,109 @@ private void runContinuation() {
      * Submits the runContinuation task to the scheduler. For the default scheduler,
      * and calling it on a worker thread, the task will be pushed to the local queue,
      * otherwise it will be pushed to an external submission queue.
+     * @param scheduler the scheduler
+     * @param retryOnOOME true to retry indefinitely if OutOfMemoryError is thrown
      * @throws RejectedExecutionException
      */
-    private void submitRunContinuation() {
-        try {
-            scheduler.execute(runContinuation);
-        } catch (RejectedExecutionException ree) {
-            submitFailed(ree);
-            throw ree;
+    @ChangesCurrentThread
+    private void submitRunContinuation(Executor scheduler, boolean retryOnOOME) {
+        boolean done = false;
+        while (!done) {
+            try {
+                // The scheduler's execute method is invoked in the context of the
+                // carrier thread. For the default scheduler this ensures that the
+                // current thread is a ForkJoinWorkerThread so the task will be pushed
+                // to the local queue. For other schedulers, it avoids deadlock that
+                // would arise due to platform and virtual threads contending for a
+                // lock on the scheduler's submission queue.
+                if (currentThread() instanceof VirtualThread vthread) {
+                    vthread.switchToCarrierThread();
+                    try {
+                        scheduler.execute(runContinuation);
+                    } finally {
+                        switchToVirtualThread(vthread);
+                    }
+                } else {
+                    scheduler.execute(runContinuation);
+                }
+                done = true;
+            } catch (RejectedExecutionException ree) {
+                submitFailed(ree);
+                throw ree;
+            } catch (OutOfMemoryError e) {
+                if (retryOnOOME) {
+                    U.park(false, 100_000_000); // 100ms
+                } else {
+                    throw e;
+                }
+            }
         }
     }
 
     /**
      * Submits the runContinuation task to given scheduler with a lazy submit.
+     * If OutOfMemoryError is thrown then the submit will be retried until it succeeds.
      * @throws RejectedExecutionException
      * @see ForkJoinPool#lazySubmit(ForkJoinTask)
      */
     private void lazySubmitRunContinuation(ForkJoinPool pool) {
+        assert Thread.currentThread() instanceof CarrierThread;
         try {
             pool.lazySubmit(ForkJoinTask.adapt(runContinuation));
         } catch (RejectedExecutionException ree) {
             submitFailed(ree);
             throw ree;
+        } catch (OutOfMemoryError e) {
+            submitRunContinuation(pool, true);
         }
     }
 
     /**
      * Submits the runContinuation task to the given scheduler as an external submit.
+     * If OutOfMemoryError is thrown then the submit will be retried until it succeeds.
      * @throws RejectedExecutionException
      * @see ForkJoinPool#externalSubmit(ForkJoinTask)
      */
     private void externalSubmitRunContinuation(ForkJoinPool pool) {
+        assert Thread.currentThread() instanceof CarrierThread;
         try {
             pool.externalSubmit(ForkJoinTask.adapt(runContinuation));
         } catch (RejectedExecutionException ree) {
             submitFailed(ree);
             throw ree;
+        } catch (OutOfMemoryError e) {
+            submitRunContinuation(pool, true);
+        }
+    }
+
+    /**
+     * Submits the runContinuation task to the scheduler. For the default scheduler,
+     * and calling it on a worker thread, the task will be pushed to the local queue,
+     * otherwise it will be pushed to an external submission queue.
+     * If OutOfMemoryError is thrown then the submit will be retried until it succeeds.
+     * @throws RejectedExecutionException
+     */
+    private void submitRunContinuation() {
+        submitRunContinuation(scheduler, true);
+    }
+
+    /**
+     * Submits the runContinuation task to the scheduler. For the default scheduler, and
+     * calling it a virtual thread that uses the default scheduler, the task will be
+     * pushed to an external submission queue. This method may throw OutOfMemoryError.
+     * @throws RejectedExecutionException
+     * @throws OutOfMemoryError
+     */
+    private void externalSubmitRunContinuationOrThrow() {
+        if (scheduler == DEFAULT_SCHEDULER && currentCarrierThread() instanceof CarrierThread ct) {
+            try {
+                ct.getPool().externalSubmit(ForkJoinTask.adapt(runContinuation));
+            } catch (RejectedExecutionException ree) {
+                submitFailed(ree);
+                throw ree;
+            }
+        } else {
+            submitRunContinuation(scheduler, false);
         }
     }
 
@@ -385,6 +452,8 @@ private void mount() {
     @ChangesCurrentThread
     @ReservedStackAccess
     private void unmount() {
+        assert !Thread.holdsLock(interruptLock);
+
         // set Thread.currentThread() to return the platform thread
         Thread carrier = this.carrierThread;
         carrier.setCurrentThread(carrier);
@@ -417,7 +486,7 @@ private void switchToCarrierThread() {
      */
     @ChangesCurrentThread
     @JvmtiMountTransition
-    private void switchToVirtualThread(VirtualThread vthread) {
+    private static void switchToVirtualThread(VirtualThread vthread) {
         Thread carrier = vthread.carrierThread;
         assert carrier == Thread.currentCarrierThread();
         carrier.setCurrentThread(vthread);
@@ -474,13 +543,12 @@ private void afterYield() {
 
             // may have been unparked while parking
             if (parkPermit && compareAndSetState(newState, UNPARKED)) {
-                // lazy submit to continue on the current thread as carrier if possible
-                if (currentThread() instanceof CarrierThread ct) {
+                // lazy submit to continue on the current carrier if possible
+                if (currentThread() instanceof CarrierThread ct && ct.getQueuedTaskCount() == 0) {
                     lazySubmitRunContinuation(ct.getPool());
                 } else {
                     submitRunContinuation();
                 }
-
             }
             return;
         }
@@ -561,8 +629,8 @@ void start(ThreadContainer container) {
             // scoped values may be inherited
             inheritScopedValueBindings(container);
 
-            // submit task to run thread
-            submitRunContinuation();
+            // submit task to run thread, using externalSubmit if possible
+            externalSubmitRunContinuationOrThrow();
             started = true;
         } finally {
             if (!started) {
@@ -707,7 +775,7 @@ private Future<?> scheduleUnpark(long nanos) {
         // need to switch to current carrier thread to avoid nested parking
         switchToCarrierThread();
         try {
-            return UNPARKER.schedule(this::unpark, nanos, NANOSECONDS);
+            return schedule(this::unpark, nanos, NANOSECONDS);
         } finally {
             switchToVirtualThread(this);
         }
@@ -718,6 +786,7 @@ private Future<?> scheduleUnpark(long nanos) {
      */
     @ChangesCurrentThread
     private void cancel(Future<?> future) {
+        assert Thread.currentThread() == this;
         if (!future.isDone()) {
             // need to switch to current carrier thread to avoid nested parking
             switchToCarrierThread();
@@ -730,33 +799,26 @@ private void cancel(Future<?> future) {
     }
 
     /**
-     * Re-enables this virtual thread for scheduling. If the virtual thread was
-     * {@link #park() parked} then it will be unblocked, otherwise its next call
-     * to {@code park} or {@linkplain #parkNanos(long) parkNanos} is guaranteed
-     * not to block.
+     * Re-enables this virtual thread for scheduling. If this virtual thread is parked
+     * then its task is scheduled to continue, otherwise its next call to {@code park} or
+     * {@linkplain #parkNanos(long) parkNanos} is guaranteed not to block.
      * @throws RejectedExecutionException if the scheduler cannot accept a task
      */
     @Override
-    @ChangesCurrentThread
     void unpark() {
-        Thread currentThread = Thread.currentThread();
-        if (!getAndSetParkPermit(true) && currentThread != this) {
+        if (!getAndSetParkPermit(true) && currentThread() != this) {
             int s = state();
-            boolean parked = (s == PARKED) || (s == TIMED_PARKED);
-            if (parked && compareAndSetState(s, UNPARKED)) {
-                if (currentThread instanceof VirtualThread vthread) {
-                    vthread.switchToCarrierThread();
-                    try {
-                        submitRunContinuation();
-                    } finally {
-                        switchToVirtualThread(vthread);
-                    }
-                } else {
-                    submitRunContinuation();
-                }
-            } else if ((s == PINNED) || (s == TIMED_PINNED)) {
+
+            // unparked while parked
+            if ((s == PARKED || s == TIMED_PARKED) && compareAndSetState(s, UNPARKED)) {
+                submitRunContinuation();
+                return;
+            }
+
+            // unparked while parked when pinned
+            if (s == PINNED || s == TIMED_PINNED) {
                 // unpark carrier thread when pinned
-                notifyJvmtiDisableSuspend(true);
+                disableSuspendAndPreempt();
                 try {
                     synchronized (carrierThreadAccessLock()) {
                         Thread carrier = carrierThread;
@@ -765,8 +827,9 @@ void unpark() {
                         }
                     }
                 } finally {
-                    notifyJvmtiDisableSuspend(false);
+                    enableSuspendAndPreempt();
                 }
+                return;
             }
         }
     }
@@ -859,11 +922,11 @@ boolean joinNanos(long nanos) throws InterruptedException {
 
     @Override
     void blockedOn(Interruptible b) {
-        notifyJvmtiDisableSuspend(true);
+        disableSuspendAndPreempt();
         try {
             super.blockedOn(b);
         } finally {
-            notifyJvmtiDisableSuspend(false);
+            enableSuspendAndPreempt();
         }
     }
 
@@ -874,9 +937,9 @@ public void interrupt() {
             checkAccess();
 
             // if current thread is a virtual thread then prevent it from being
-            // suspended when entering or holding interruptLock
+            // suspended or unmounted when entering or holding interruptLock
             Interruptible blocker;
-            notifyJvmtiDisableSuspend(true);
+            disableSuspendAndPreempt();
             try {
                 synchronized (interruptLock) {
                     interrupted = true;
@@ -890,18 +953,22 @@ public void interrupt() {
                     if (carrier != null) carrier.setInterrupt();
                 }
             } finally {
-                notifyJvmtiDisableSuspend(false);
+                enableSuspendAndPreempt();
             }
 
             // notify blocker after releasing interruptLock
             if (blocker != null) {
                 blocker.postInterrupt();
             }
+
+            // make available parking permit, unpark thread if parked
+            unpark();
+
         } else {
             interrupted = true;
             carrierThread.setInterrupt();
+            setParkPermit(true);
         }
-        unpark();
     }
 
     @Override
@@ -914,14 +981,14 @@ boolean getAndClearInterrupt() {
         assert Thread.currentThread() == this;
         boolean oldValue = interrupted;
         if (oldValue) {
-            notifyJvmtiDisableSuspend(true);
+            disableSuspendAndPreempt();
             try {
                 synchronized (interruptLock) {
                     interrupted = false;
                     carrierThread.clearInterrupt();
                 }
             } finally {
-                notifyJvmtiDisableSuspend(false);
+                enableSuspendAndPreempt();
             }
         }
         return oldValue;
@@ -946,16 +1013,18 @@ Thread.State threadState() {
                 return Thread.State.RUNNABLE;
             case RUNNING:
                 // if mounted then return state of carrier thread
-                notifyJvmtiDisableSuspend(true);
-                try {
-                    synchronized (carrierThreadAccessLock()) {
-                        Thread carrierThread = this.carrierThread;
-                        if (carrierThread != null) {
-                            return carrierThread.threadState();
+                if (Thread.currentThread() != this) {
+                    disableSuspendAndPreempt();
+                    try {
+                        synchronized (carrierThreadAccessLock()) {
+                            Thread carrierThread = this.carrierThread;
+                            if (carrierThread != null) {
+                                return carrierThread.threadState();
+                            }
                         }
+                    } finally {
+                        enableSuspendAndPreempt();
                     }
-                } finally {
-                    notifyJvmtiDisableSuspend(false);
                 }
                 // runnable, mounted
                 return Thread.State.RUNNABLE;
@@ -1068,32 +1137,49 @@ public String toString() {
             sb.append(name);
         }
         sb.append("]/");
-        Thread carrier = carrierThread;
-        if (carrier != null) {
-            // include the carrier thread state and name when mounted
-            notifyJvmtiDisableSuspend(true);
+
+        // add the carrier state and thread name when mounted
+        boolean mounted;
+        if (Thread.currentThread() == this) {
+            mounted = appendCarrierInfo(sb);
+        } else {
+            disableSuspendAndPreempt();
             try {
                 synchronized (carrierThreadAccessLock()) {
-                    carrier = carrierThread;
-                    if (carrier != null) {
-                        String stateAsString = carrier.threadState().toString();
-                        sb.append(stateAsString.toLowerCase(Locale.ROOT));
-                        sb.append('@');
-                        sb.append(carrier.getName());
-                    }
+                    mounted = appendCarrierInfo(sb);
                 }
             } finally {
-                notifyJvmtiDisableSuspend(false);
+                enableSuspendAndPreempt();
             }
         }
-        // include virtual thread state when not mounted
-        if (carrier == null) {
+
+        // add virtual thread state when not mounted
+        if (!mounted) {
             String stateAsString = threadState().toString();
             sb.append(stateAsString.toLowerCase(Locale.ROOT));
         }
+
         return sb.toString();
     }
 
+    /**
+     * Appends the carrier state and thread name to the string buffer if mounted.
+     * @return true if mounted, false if not mounted
+     */
+    private boolean appendCarrierInfo(StringBuilder sb) {
+        assert Thread.currentThread() == this || Thread.holdsLock(carrierThreadAccessLock());
+        Thread carrier = carrierThread;
+        if (carrier != null) {
+            String stateAsString = carrier.threadState().toString();
+            sb.append(stateAsString.toLowerCase(Locale.ROOT));
+            sb.append('@');
+            sb.append(carrier.getName());
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     @Override
     public int hashCode() {
         return (int) threadId();
@@ -1127,6 +1213,22 @@ private Object carrierThreadAccessLock() {
         return interruptLock;
     }
 
+    /**
+     * Disallow the current thread be suspended or preempted.
+     */
+    private void disableSuspendAndPreempt() {
+        notifyJvmtiDisableSuspend(true);
+        Continuation.pin();
+    }
+
+    /**
+     * Allow the current thread be suspended or preempted.
+     */
+    private void enableSuspendAndPreempt() {
+        Continuation.unpin();
+        notifyJvmtiDisableSuspend(false);
+    }
+
     // -- wrappers for get/set of state, parking permit, and carrier thread --
 
     private int state() {
@@ -1188,10 +1290,16 @@ private void setCarrierThread(Thread carrier) {
     private static native void registerNatives();
     static {
         registerNatives();
+
+        // ensure VTHREAD_GROUP is created, may be accessed by JVMTI
+        var group = Thread.virtualThreadGroup();
+
+        // ensure VirtualThreadPinnedEvent is loaded/initialized
+        U.ensureClassInitialized(VirtualThreadPinnedEvent.class);
     }
 
     /**
-     * Creates the default scheduler.
+     * Creates the default ForkJoinPool scheduler.
      */
     @SuppressWarnings("removal")
     private static ForkJoinPool createDefaultScheduler() {
@@ -1229,22 +1337,42 @@ private static ForkJoinPool createDefaultScheduler() {
     }
 
     /**
-     * Creates the ScheduledThreadPoolExecutor used for timed unpark.
+     * Schedule a runnable task to run after a delay.
      */
-    private static ScheduledExecutorService createDelayedTaskScheduler() {
-        String propValue = GetPropertyAction.privilegedGetProperty("jdk.unparker.maxPoolSize");
-        int poolSize;
+    private static Future<?> schedule(Runnable command, long delay, TimeUnit unit) {
+        long tid = Thread.currentThread().threadId();
+        int index = (int) tid & (DELAYED_TASK_SCHEDULERS.length - 1);
+        return DELAYED_TASK_SCHEDULERS[index].schedule(command, delay, unit);
+    }
+
+    /**
+     * Creates the ScheduledThreadPoolExecutors used to execute delayed tasks.
+     */
+    private static ScheduledExecutorService[] createDelayedTaskSchedulers() {
+        String propName = "jdk.virtualThreadScheduler.timerQueues";
+        String propValue = GetPropertyAction.privilegedGetProperty(propName);
+        int queueCount;
         if (propValue != null) {
-            poolSize = Integer.parseInt(propValue);
+            queueCount = Integer.parseInt(propValue);
+            if (queueCount != Integer.highestOneBit(queueCount)) {
+                throw new RuntimeException("Value of " + propName + " must be power of 2");
+            }
         } else {
-            poolSize = 1;
+            int ncpus = Runtime.getRuntime().availableProcessors();
+            queueCount = Math.max(Integer.highestOneBit(ncpus / 4), 1);
+        }
+        var schedulers = new ScheduledExecutorService[queueCount];
+        for (int i = 0; i < queueCount; i++) {
+            ScheduledThreadPoolExecutor stpe = (ScheduledThreadPoolExecutor)
+                Executors.newScheduledThreadPool(1, task -> {
+                    Thread t = InnocuousThread.newThread("VirtualThread-unparker", task);
+                    t.setDaemon(true);
+                    return t;
+                });
+            stpe.setRemoveOnCancelPolicy(true);
+            schedulers[i] = stpe;
         }
-        ScheduledThreadPoolExecutor stpe = (ScheduledThreadPoolExecutor)
-            Executors.newScheduledThreadPool(poolSize, task -> {
-                return InnocuousThread.newThread("VirtualThread-unparker", task);
-            });
-        stpe.setRemoveOnCancelPolicy(true);
-        return stpe;
+        return schedulers;
     }
 
     /**
diff --git a/src/java.base/share/classes/java/lang/classfile/AccessFlags.java b/src/java.base/share/classes/java/lang/classfile/AccessFlags.java
index 283094b81d6..6c6ac75e648 100644
--- a/src/java.base/share/classes/java/lang/classfile/AccessFlags.java
+++ b/src/java.base/share/classes/java/lang/classfile/AccessFlags.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -64,52 +64,4 @@ public sealed interface AccessFlags
      * method, or field}
      */
     AccessFlag.Location location();
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a class}
-     * @param mask the flags to be set, as a bit mask
-     */
-    static AccessFlags ofClass(int mask) {
-        return new AccessFlagsImpl(AccessFlag.Location.CLASS, mask);
-    }
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a class}
-     * @param flags the flags to be set
-     */
-    static AccessFlags ofClass(AccessFlag... flags) {
-        return new AccessFlagsImpl(AccessFlag.Location.CLASS, flags);
-    }
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a field}
-     * @param mask the flags to be set, as a bit mask
-     */
-    static AccessFlags ofField(int mask) {
-        return new AccessFlagsImpl(AccessFlag.Location.FIELD, mask);
-    }
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a field}
-     * @param flags the flags to be set
-     */
-    static AccessFlags ofField(AccessFlag... flags) {
-        return new AccessFlagsImpl(AccessFlag.Location.FIELD, flags);
-    }
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a method}
-     * @param mask the flags to be set, as a bit mask
-     */
-    static AccessFlags ofMethod(int mask) {
-        return new AccessFlagsImpl(AccessFlag.Location.METHOD, mask);
-    }
-
-    /**
-     * {@return an {@linkplain AccessFlags} for a method}
-     * @param flags the flags to be set
-     */
-    static AccessFlags ofMethod(AccessFlag... flags) {
-        return new AccessFlagsImpl(AccessFlag.Location.METHOD, flags);
-    }
 }
diff --git a/src/java.base/share/classes/java/lang/classfile/AttributedElement.java b/src/java.base/share/classes/java/lang/classfile/AttributedElement.java
index 63b2f1e03a9..d66806ca93b 100644
--- a/src/java.base/share/classes/java/lang/classfile/AttributedElement.java
+++ b/src/java.base/share/classes/java/lang/classfile/AttributedElement.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,7 @@
 package java.lang.classfile;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 
@@ -83,6 +84,6 @@ default <T extends Attribute<T>> List<T> findAttributes(AttributeMapper<T> attr)
                 list.add(t);
             }
         }
-        return list;
+        return Collections.unmodifiableList(list);
     }
 }
diff --git a/src/java.base/share/classes/java/lang/classfile/ClassBuilder.java b/src/java.base/share/classes/java/lang/classfile/ClassBuilder.java
index a55b93e7c07..7ad6e94df3f 100644
--- a/src/java.base/share/classes/java/lang/classfile/ClassBuilder.java
+++ b/src/java.base/share/classes/java/lang/classfile/ClassBuilder.java
@@ -34,6 +34,8 @@
 
 import java.lang.classfile.constantpool.ClassEntry;
 import java.lang.classfile.constantpool.Utf8Entry;
+
+import jdk.internal.classfile.impl.AccessFlagsImpl;
 import jdk.internal.classfile.impl.ChainedClassBuilder;
 import jdk.internal.classfile.impl.DirectClassBuilder;
 import jdk.internal.classfile.impl.Util;
@@ -73,7 +75,7 @@ default ClassBuilder withVersion(int major, int minor) {
      * @return this builder
      */
     default ClassBuilder withFlags(int flags) {
-        return with(AccessFlags.ofClass(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.CLASS, flags));
     }
 
     /**
@@ -82,7 +84,7 @@ default ClassBuilder withFlags(int flags) {
      * @return this builder
      */
     default ClassBuilder withFlags(AccessFlag... flags) {
-        return with(AccessFlags.ofClass(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.CLASS, flags));
     }
 
     /**
diff --git a/src/java.base/share/classes/java/lang/classfile/ClassSignature.java b/src/java.base/share/classes/java/lang/classfile/ClassSignature.java
index 852d5f9baf4..5c55950547e 100644
--- a/src/java.base/share/classes/java/lang/classfile/ClassSignature.java
+++ b/src/java.base/share/classes/java/lang/classfile/ClassSignature.java
@@ -76,7 +76,7 @@ public static ClassSignature of(List<Signature.TypeParam> typeParameters,
                                     Signature.ClassTypeSig superclassSignature,
                                     Signature.ClassTypeSig... superinterfaceSignatures) {
         return new SignaturesImpl.ClassSignatureImpl(
-                requireNonNull(typeParameters),
+                List.copyOf(requireNonNull(typeParameters)),
                 requireNonNull(superclassSignature),
                 List.of(superinterfaceSignatures));
     }
diff --git a/src/java.base/share/classes/java/lang/classfile/CodeModel.java b/src/java.base/share/classes/java/lang/classfile/CodeModel.java
index 45488561c1a..ba816f20805 100644
--- a/src/java.base/share/classes/java/lang/classfile/CodeModel.java
+++ b/src/java.base/share/classes/java/lang/classfile/CodeModel.java
@@ -43,17 +43,7 @@
 @PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
 public sealed interface CodeModel
         extends CompoundElement<CodeElement>, AttributedElement, MethodElement
-        permits CodeAttribute, BufferedCodeBuilder.Model, CodeImpl {
-
-    /**
-     * {@return the maximum size of the local variable table}
-     */
-    int maxLocals();
-
-    /**
-     * {@return the maximum size of the operand stack}
-     */
-    int maxStack();
+        permits CodeAttribute, BufferedCodeBuilder.Model {
 
     /**
      * {@return the enclosing method, if known}
diff --git a/src/java.base/share/classes/java/lang/classfile/CompoundElement.java b/src/java.base/share/classes/java/lang/classfile/CompoundElement.java
index 12904c9dd59..9fcf02204cb 100644
--- a/src/java.base/share/classes/java/lang/classfile/CompoundElement.java
+++ b/src/java.base/share/classes/java/lang/classfile/CompoundElement.java
@@ -25,6 +25,7 @@
 package java.lang.classfile;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Spliterator;
@@ -90,7 +91,7 @@ public void accept(E e) {
                 list.add(e);
             }
         });
-        return list;
+        return Collections.unmodifiableList(list);
     }
 
 }
diff --git a/src/java.base/share/classes/java/lang/classfile/FieldBuilder.java b/src/java.base/share/classes/java/lang/classfile/FieldBuilder.java
index c0e733676f7..d9a8f6b2fc3 100644
--- a/src/java.base/share/classes/java/lang/classfile/FieldBuilder.java
+++ b/src/java.base/share/classes/java/lang/classfile/FieldBuilder.java
@@ -26,6 +26,8 @@
 package java.lang.classfile;
 
 import java.lang.classfile.constantpool.Utf8Entry;
+
+import jdk.internal.classfile.impl.AccessFlagsImpl;
 import jdk.internal.classfile.impl.ChainedFieldBuilder;
 import jdk.internal.classfile.impl.TerminalFieldBuilder;
 import java.lang.reflect.AccessFlag;
@@ -55,7 +57,7 @@ public sealed interface FieldBuilder
      * @return this builder
      */
     default FieldBuilder withFlags(int flags) {
-        return with(AccessFlags.ofField(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.FIELD, flags));
     }
 
     /**
@@ -64,7 +66,7 @@ default FieldBuilder withFlags(int flags) {
      * @return this builder
      */
     default FieldBuilder withFlags(AccessFlag... flags) {
-        return with(AccessFlags.ofField(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.FIELD, flags));
     }
 
 }
diff --git a/src/java.base/share/classes/java/lang/classfile/MethodBuilder.java b/src/java.base/share/classes/java/lang/classfile/MethodBuilder.java
index 4cf34c95ed0..7c230760f69 100644
--- a/src/java.base/share/classes/java/lang/classfile/MethodBuilder.java
+++ b/src/java.base/share/classes/java/lang/classfile/MethodBuilder.java
@@ -28,6 +28,8 @@
 import java.util.function.Consumer;
 
 import java.lang.classfile.constantpool.Utf8Entry;
+
+import jdk.internal.classfile.impl.AccessFlagsImpl;
 import jdk.internal.classfile.impl.ChainedMethodBuilder;
 import jdk.internal.classfile.impl.TerminalMethodBuilder;
 import java.lang.reflect.AccessFlag;
@@ -55,7 +57,7 @@ public sealed interface MethodBuilder
      * @return this builder
      */
     default MethodBuilder withFlags(int flags) {
-        return with(AccessFlags.ofMethod(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.METHOD, flags));
     }
 
     /**
@@ -64,7 +66,7 @@ default MethodBuilder withFlags(int flags) {
      * @return this builder
      */
     default MethodBuilder withFlags(AccessFlag... flags) {
-        return with(AccessFlags.ofMethod(flags));
+        return with(new AccessFlagsImpl(AccessFlag.Location.METHOD, flags));
     }
 
     /**
diff --git a/src/java.base/share/classes/java/lang/classfile/attribute/CodeAttribute.java b/src/java.base/share/classes/java/lang/classfile/attribute/CodeAttribute.java
index 02cbcee810f..7a4f5886580 100644
--- a/src/java.base/share/classes/java/lang/classfile/attribute/CodeAttribute.java
+++ b/src/java.base/share/classes/java/lang/classfile/attribute/CodeAttribute.java
@@ -47,6 +47,16 @@
 public sealed interface CodeAttribute extends Attribute<CodeAttribute>, CodeModel
         permits BoundAttribute.BoundCodeAttribute {
 
+    /**
+     * {@return the maximum size of the local variable table}
+     */
+    int maxLocals();
+
+    /**
+     * {@return the maximum size of the operand stack}
+     */
+    int maxStack();
+
     /**
      * {@return The length of the code array in bytes}
      */
diff --git a/src/java.base/share/classes/java/text/DecimalFormat.java b/src/java.base/share/classes/java/text/DecimalFormat.java
index 07a1c6932e7..c04abbd042f 100644
--- a/src/java.base/share/classes/java/text/DecimalFormat.java
+++ b/src/java.base/share/classes/java/text/DecimalFormat.java
@@ -430,16 +430,15 @@ public class DecimalFormat extends NumberFormat {
      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
      * This is a convenient way to obtain a
      * DecimalFormat when internationalization is not the main concern.
-     * <p>
-     * To obtain standard formats for a given locale, use the factory methods
-     * on NumberFormat such as getNumberInstance. These factories will
-     * return the most appropriate sub-class of NumberFormat for a given
-     * locale.
      *
-     * @see java.text.NumberFormat#getInstance
-     * @see java.text.NumberFormat#getNumberInstance
-     * @see java.text.NumberFormat#getCurrencyInstance
-     * @see java.text.NumberFormat#getPercentInstance
+     * @apiNote To obtain standard formats for a given locale, use the
+     * {@code NumberFormat} factory methods such as {@link
+     * NumberFormat#getNumberInstance(Locale)}. These factories will return the most
+     * appropriate subclass of NumberFormat for a given locale.
+     * @see NumberFormat#getInstance(Locale)
+     * @see NumberFormat#getNumberInstance(Locale)
+     * @see NumberFormat#getCurrencyInstance(Locale)
+     * @see NumberFormat#getPercentInstance(Locale)
      */
     @SuppressWarnings("this-escape")
     public DecimalFormat() {
@@ -464,19 +463,18 @@ public DecimalFormat() {
      * DecimalFormat when internationalization is not the main concern.
      * The number of maximum integer digits is usually not derived from the pattern.
      * See the note in the {@link ##patterns Patterns} section for more detail.
-     * <p>
-     * To obtain standard formats for a given locale, use the factory methods
-     * on NumberFormat such as getNumberInstance. These factories will
-     * return the most appropriate sub-class of NumberFormat for a given
-     * locale.
      *
+     * @apiNote To obtain standard formats for a given locale, use the
+     * {@code NumberFormat} factory methods such as {@link
+     * NumberFormat#getNumberInstance(Locale)}. These factories will return the most
+     * appropriate subclass of NumberFormat for a given locale.
      * @param pattern a non-localized pattern string.
      * @throws    NullPointerException if {@code pattern} is null
      * @throws    IllegalArgumentException if the given pattern is invalid.
-     * @see java.text.NumberFormat#getInstance
-     * @see java.text.NumberFormat#getNumberInstance
-     * @see java.text.NumberFormat#getCurrencyInstance
-     * @see java.text.NumberFormat#getPercentInstance
+     * @see NumberFormat#getInstance(Locale)
+     * @see NumberFormat#getNumberInstance(Locale)
+     * @see NumberFormat#getCurrencyInstance(Locale)
+     * @see NumberFormat#getPercentInstance(Locale)
      */
     @SuppressWarnings("this-escape")
     public DecimalFormat(String pattern) {
@@ -492,21 +490,20 @@ public DecimalFormat(String pattern) {
      * behavior of the format.
      * The number of maximum integer digits is usually not derived from the pattern.
      * See the note in the {@link ##patterns Patterns} section for more detail.
-     * <p>
-     * To obtain standard formats for a given
-     * locale, use the factory methods on NumberFormat such as
-     * getInstance or getCurrencyInstance. If you need only minor adjustments
-     * to a standard format, you can modify the format returned by
-     * a NumberFormat factory method.
      *
+     * @apiNote To obtain standard formats for a given locale, use the
+     * {@code NumberFormat} factory methods such as {@link
+     * NumberFormat#getInstance(Locale)} or {@link NumberFormat#getCurrencyInstance(Locale)}.
+     * If you need only minor adjustments to a standard format, you can modify
+     * the format returned by a NumberFormat factory method.
      * @param pattern a non-localized pattern string
      * @param symbols the set of symbols to be used
      * @throws    NullPointerException if any of the given arguments is null
      * @throws    IllegalArgumentException if the given pattern is invalid
-     * @see java.text.NumberFormat#getInstance
-     * @see java.text.NumberFormat#getNumberInstance
-     * @see java.text.NumberFormat#getCurrencyInstance
-     * @see java.text.NumberFormat#getPercentInstance
+     * @see NumberFormat#getInstance(Locale)
+     * @see NumberFormat#getNumberInstance(Locale)
+     * @see NumberFormat#getCurrencyInstance(Locale)
+     * @see NumberFormat#getPercentInstance(Locale)
      * @see java.text.DecimalFormatSymbols
      */
     @SuppressWarnings("this-escape")
@@ -522,8 +519,8 @@ public DecimalFormat (String pattern, DecimalFormatSymbols symbols) {
      * Formats a number and appends the resulting text to the given string
      * buffer.
      * The number can be of any subclass of {@link java.lang.Number}.
-     * <p>
-     * This implementation uses the maximum precision permitted.
+     *
+     * @implSpec This implementation uses the maximum precision permitted.
      * @param number     the number to format
      * @param toAppendTo the {@code StringBuffer} to which the formatted
      *                   text is to be appended
diff --git a/src/java.base/share/classes/java/time/LocalDate.java b/src/java.base/share/classes/java/time/LocalDate.java
index b0d7ad33c8a..2d71fb1ceca 100644
--- a/src/java.base/share/classes/java/time/LocalDate.java
+++ b/src/java.base/share/classes/java/time/LocalDate.java
@@ -2147,11 +2147,20 @@ public int hashCode() {
      */
     @Override
     public String toString() {
+        var buf = new StringBuilder(10);
+        formatTo(buf);
+        return buf.toString();
+    }
+
+    /**
+     * Prints the toString result to the given buf, avoiding extra string allocations.
+     * Requires extra capacity of 10 to avoid StringBuilder reallocation.
+     */
+    void formatTo(StringBuilder buf) {
         int yearValue = year;
         int monthValue = month;
         int dayValue = day;
         int absYear = Math.abs(yearValue);
-        StringBuilder buf = new StringBuilder(10);
         if (absYear < 1000) {
             if (yearValue < 0) {
                 buf.append('-');
@@ -2164,11 +2173,10 @@ public String toString() {
             }
             buf.append(yearValue);
         }
-        return buf.append(monthValue < 10 ? "-0" : "-")
-            .append(monthValue)
-            .append(dayValue < 10 ? "-0" : "-")
-            .append(dayValue)
-            .toString();
+        buf.append(monthValue < 10 ? "-0" : "-")
+           .append(monthValue)
+           .append(dayValue < 10 ? "-0" : "-")
+           .append(dayValue);
     }
 
     //-----------------------------------------------------------------------
diff --git a/src/java.base/share/classes/java/time/LocalDateTime.java b/src/java.base/share/classes/java/time/LocalDateTime.java
index 024aa1dacbe..d14afb7d78f 100644
--- a/src/java.base/share/classes/java/time/LocalDateTime.java
+++ b/src/java.base/share/classes/java/time/LocalDateTime.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1965,7 +1965,11 @@ public int hashCode() {
      */
     @Override
     public String toString() {
-        return date.toString() + 'T' + time.toString();
+        var buf = new StringBuilder(29);
+        date.formatTo(buf);
+        buf.append('T');
+        time.formatTo(buf);
+        return buf.toString();
     }
 
     //-----------------------------------------------------------------------
diff --git a/src/java.base/share/classes/java/time/LocalTime.java b/src/java.base/share/classes/java/time/LocalTime.java
index fd2c5ce4d45..f28f8d3c599 100644
--- a/src/java.base/share/classes/java/time/LocalTime.java
+++ b/src/java.base/share/classes/java/time/LocalTime.java
@@ -1631,7 +1631,16 @@ public int hashCode() {
      */
     @Override
     public String toString() {
-        StringBuilder buf = new StringBuilder(18);
+        var buf = new StringBuilder(18);
+        formatTo(buf);
+        return buf.toString();
+    }
+
+    /**
+     * Prints the toString result to the given buf, avoiding extra string allocations.
+     * Requires extra capacity of 18 to avoid StringBuilder reallocation.
+     */
+    void formatTo(StringBuilder buf) {
         int hourValue = hour;
         int minuteValue = minute;
         int secondValue = second;
@@ -1657,7 +1666,6 @@ public String toString() {
                 buf.append(digits);
             }
         }
-        return buf.toString();
     }
 
     //-----------------------------------------------------------------------
diff --git a/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java b/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java
index 46a80deee00..33dea914b66 100644
--- a/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java
+++ b/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java
@@ -121,6 +121,8 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import jdk.internal.util.DecimalDigits;
+
 import sun.text.spi.JavaTimeDateTimePatternProvider;
 import sun.util.locale.provider.CalendarDataUtility;
 import sun.util.locale.provider.LocaleProviderAdapter;
@@ -2908,24 +2910,6 @@ NumberPrinterParser withSubsequentWidth(int subsequentWidth) {
             return new NumberPrinterParser(field, minWidth, maxWidth, signStyle, this.subsequentWidth + subsequentWidth);
         }
 
-        /*
-         * Copied from Long.stringSize
-         */
-        private static int stringSize(long x) {
-            int d = 1;
-            if (x >= 0) {
-                d = 0;
-                x = -x;
-            }
-            long p = -10;
-            for (int i = 1; i < 19; i++) {
-                if (x > p)
-                    return i + d;
-                p = 10 * p;
-            }
-            return 19 + d;
-        }
-
         @Override
         public boolean format(DateTimePrintContext context, StringBuilder buf) {
             Long valueLong = context.getValue(field);
@@ -2934,7 +2918,7 @@ public boolean format(DateTimePrintContext context, StringBuilder buf) {
             }
             long value = getValue(context, valueLong);
             DecimalStyle decimalStyle = context.getDecimalStyle();
-            int size = stringSize(value);
+            int size = DecimalDigits.stringSize(value);
             if (value < 0) {
                 size--;
             }
@@ -3369,17 +3353,6 @@ boolean isFixedWidth(DateTimeParseContext context) {
             return false;
         }
 
-        // Simplified variant of Integer.stringSize that assumes positive values
-        private static int stringSize(int x) {
-            int p = 10;
-            for (int i = 1; i < 10; i++) {
-                if (x < p)
-                    return i;
-                p = 10 * p;
-            }
-            return 10;
-        }
-
         private static final int[] TENS = new int[] {
             1,
             10,
@@ -3400,7 +3373,7 @@ public boolean format(DateTimePrintContext context, StringBuilder buf) {
             }
             int val = field.range().checkValidIntValue(value, field);
             DecimalStyle decimalStyle = context.getDecimalStyle();
-            int stringSize = stringSize(val);
+            int stringSize = DecimalDigits.stringSize(val);
             char zero = decimalStyle.getZeroDigit();
             if (val == 0 || stringSize < 10 - maxWidth) {
                 // 0 or would round down to 0
diff --git a/src/java.base/share/classes/java/util/concurrent/locks/LockSupport.java b/src/java.base/share/classes/java/util/concurrent/locks/LockSupport.java
index 28fe0d4dca3..d6c45c7b04f 100644
--- a/src/java.base/share/classes/java/util/concurrent/locks/LockSupport.java
+++ b/src/java.base/share/classes/java/util/concurrent/locks/LockSupport.java
@@ -35,7 +35,9 @@
 
 package java.util.concurrent.locks;
 
-import jdk.internal.misc.VirtualThreads;
+import java.util.concurrent.TimeUnit;
+import jdk.internal.access.JavaLangAccess;
+import jdk.internal.access.SharedSecrets;
 import jdk.internal.misc.Unsafe;
 
 /**
@@ -176,7 +178,7 @@ public static void setCurrentBlocker(Object blocker) {
     public static void unpark(Thread thread) {
         if (thread != null) {
             if (thread.isVirtual()) {
-                VirtualThreads.unpark(thread);
+                JLA.unparkVirtualThread(thread);
             } else {
                 U.unpark(thread);
             }
@@ -216,7 +218,7 @@ public static void park(Object blocker) {
         setBlocker(t, blocker);
         try {
             if (t.isVirtual()) {
-                VirtualThreads.park();
+                JLA.parkVirtualThread();
             } else {
                 U.park(false, 0L);
             }
@@ -264,7 +266,7 @@ public static void parkNanos(Object blocker, long nanos) {
             setBlocker(t, blocker);
             try {
                 if (t.isVirtual()) {
-                    VirtualThreads.park(nanos);
+                    JLA.parkVirtualThread(nanos);
                 } else {
                     U.park(false, nanos);
                 }
@@ -311,11 +313,7 @@ public static void parkUntil(Object blocker, long deadline) {
         Thread t = Thread.currentThread();
         setBlocker(t, blocker);
         try {
-            if (t.isVirtual()) {
-                VirtualThreads.parkUntil(deadline);
-            } else {
-                U.park(true, deadline);
-            }
+            parkUntil(deadline);
         } finally {
             setBlocker(t, null);
         }
@@ -366,7 +364,7 @@ public static Object getBlocker(Thread t) {
      */
     public static void park() {
         if (Thread.currentThread().isVirtual()) {
-            VirtualThreads.park();
+            JLA.parkVirtualThread();
         } else {
             U.park(false, 0L);
         }
@@ -405,7 +403,7 @@ public static void park() {
     public static void parkNanos(long nanos) {
         if (nanos > 0) {
             if (Thread.currentThread().isVirtual()) {
-                VirtualThreads.park(nanos);
+                JLA.parkVirtualThread(nanos);
             } else {
                 U.park(false, nanos);
             }
@@ -444,7 +442,8 @@ public static void parkNanos(long nanos) {
      */
     public static void parkUntil(long deadline) {
         if (Thread.currentThread().isVirtual()) {
-            VirtualThreads.parkUntil(deadline);
+            long millis = deadline - System.currentTimeMillis();
+            JLA.parkVirtualThread(TimeUnit.MILLISECONDS.toNanos(millis));
         } else {
             U.park(true, deadline);
         }
@@ -462,4 +461,5 @@ static final long getThreadId(Thread thread) {
     private static final long PARKBLOCKER
         = U.objectFieldOffset(Thread.class, "parkBlocker");
 
+    private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
 }
diff --git a/src/java.base/share/classes/jdk/internal/access/JavaLangAccess.java b/src/java.base/share/classes/jdk/internal/access/JavaLangAccess.java
index 2254c065e2e..24aeabf6d36 100644
--- a/src/java.base/share/classes/jdk/internal/access/JavaLangAccess.java
+++ b/src/java.base/share/classes/jdk/internal/access/JavaLangAccess.java
@@ -42,7 +42,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.stream.Stream;
@@ -459,8 +458,6 @@ public interface JavaLangAccess {
      */
     Object classData(Class<?> c);
 
-    int stringSize(long i);
-
     int getCharsLatin1(long i, int index, byte[] buf);
 
     int getCharsUTF16(long i, int index, byte[] buf);
@@ -504,11 +501,6 @@ public interface JavaLangAccess {
      */
     Thread currentCarrierThread();
 
-    /**
-     * Executes the given value returning task on the current carrier thread.
-     */
-    <V> V executeOnCarrierThread(Callable<V> task) throws Exception;
-
     /**
      * Returns the value of the current carrier thread's copy of a thread-local.
      */
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/AbstractUnboundModel.java b/src/java.base/share/classes/jdk/internal/classfile/impl/AbstractUnboundModel.java
index 788bdffe1cd..9502ff7b246 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/AbstractUnboundModel.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/AbstractUnboundModel.java
@@ -24,6 +24,7 @@
  */
 package jdk.internal.classfile.impl;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
 import java.util.stream.Stream;
@@ -35,13 +36,13 @@
 
 public abstract sealed class AbstractUnboundModel<E extends ClassFileElement>
         extends AbstractElement
-        implements CompoundElement<E>, AttributedElement, Util.Writable
+        implements CompoundElement<E>, AttributedElement
         permits BufferedCodeBuilder.Model, BufferedFieldBuilder.Model, BufferedMethodBuilder.Model {
-    private final List<E> elements;
+    final List<E> elements;
     private List<Attribute<?>> attributes;
 
     public AbstractUnboundModel(List<E> elements) {
-        this.elements = elements;
+        this.elements = Collections.unmodifiableList(elements);
     }
 
     @Override
@@ -63,8 +64,11 @@ public List<E> elementList() {
     public List<Attribute<?>> attributes() {
         if (attributes == null)
             attributes = elements.stream()
-                                 .filter(e -> e instanceof Attribute)
-                                 .<Attribute<?>>map(e -> (Attribute<?>) e)
+                                 .<Attribute<?>>mapMulti((e, sink) -> {
+                                     if (e instanceof Attribute<?> attr) {
+                                         sink.accept(attr);
+                                     }
+                                 })
                                  .toList();
         return attributes;
     }
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/BoundAttribute.java b/src/java.base/share/classes/jdk/internal/classfile/impl/BoundAttribute.java
index a0428d9d09d..d5ed0c14bce 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/BoundAttribute.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/BoundAttribute.java
@@ -39,6 +39,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Function;
 
@@ -134,7 +135,6 @@ public static List<Attribute<?>> readAttributes(AttributedElement enclosing, Cla
         var filled = new ArrayList<Attribute<?>>(size);
         int p = pos + 2;
         int cfLen = reader.classfileLength();
-        var apo = ((ClassReaderImpl)reader).context().attributesProcessingOption();
         for (int i = 0; i < size; ++i) {
             Utf8Entry name = reader.readEntry(p, Utf8Entry.class);
             int len = reader.readInt(p + 2);
@@ -148,7 +148,7 @@ public static List<Attribute<?>> readAttributes(AttributedElement enclosing, Cla
                 mapper = customAttributes.apply(name);
             }
             if (mapper != null) {
-                filled.add((Attribute)mapper.readAttribute(enclosing, reader, p));
+                filled.add((Attribute<?>) Objects.requireNonNull(mapper.readAttribute(enclosing, reader, p)));
             } else {
                 AttributeMapper<UnknownAttribute> fakeMapper = new AttributeMapper<>() {
                     @Override
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedCodeBuilder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedCodeBuilder.java
index 4743c58607c..b690f8dbfe7 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedCodeBuilder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedCodeBuilder.java
@@ -32,9 +32,6 @@
 import java.lang.classfile.Label;
 import java.lang.classfile.MethodModel;
 import java.lang.classfile.instruction.ExceptionCatch;
-import java.lang.classfile.instruction.IncrementInstruction;
-import java.lang.classfile.instruction.LoadInstruction;
-import java.lang.classfile.instruction.StoreInstruction;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -47,7 +44,6 @@ public final class BufferedCodeBuilder
     private final ClassFileImpl context;
     private final List<CodeElement> elements = new ArrayList<>();
     private final LabelImpl startLabel, endLabel;
-    private final CodeModel original;
     private final MethodInfo methodInfo;
     private boolean finished;
     private int maxLocals;
@@ -60,12 +56,8 @@ public BufferedCodeBuilder(MethodInfo methodInfo,
         this.context = context;
         this.startLabel = new LabelImpl(this, -1);
         this.endLabel = new LabelImpl(this, -1);
-        this.original = original;
         this.methodInfo = methodInfo;
-        this.maxLocals = Util.maxLocals(methodInfo.methodFlags(), methodInfo.methodTypeSymbol());
-        if (original != null)
-            this.maxLocals = Math.max(this.maxLocals, original.maxLocals());
-
+        this.maxLocals = TerminalCodeBuilder.setupTopLocal(methodInfo, original);
         elements.add(startLabel);
     }
 
@@ -156,33 +148,22 @@ public final class Model
             implements CodeModel {
 
         private Model() {
-            super(elements);
+            super(BufferedCodeBuilder.this.elements);
         }
 
         @Override
         public List<ExceptionCatch> exceptionHandlers() {
             return elements.stream()
-                           .filter(x -> x instanceof ExceptionCatch)
-                           .map(x -> (ExceptionCatch) x)
+                           .<ExceptionCatch>mapMulti((x, sink) -> {
+                               if (x instanceof ExceptionCatch ec) {
+                                   sink.accept(ec);
+                               }
+                           })
                            .toList();
         }
 
-        @Override
-        public int maxLocals() {
-            for (CodeElement element : elements) {
-                if (element instanceof LoadInstruction i)
-                    maxLocals = Math.max(maxLocals, i.slot() + i.typeKind().slotSize());
-                else if (element instanceof StoreInstruction i)
-                    maxLocals = Math.max(maxLocals, i.slot() + i.typeKind().slotSize());
-                else if (element instanceof IncrementInstruction i)
-                    maxLocals = Math.max(maxLocals, i.slot() + 1);
-            }
-            return maxLocals;
-        }
-
-        @Override
-        public int maxStack() {
-            throw new UnsupportedOperationException("nyi");
+        int curTopLocal() {
+            return BufferedCodeBuilder.this.curTopLocal();
         }
 
         @Override
@@ -200,11 +181,6 @@ public void accept(CodeBuilder cb) {
             });
         }
 
-        @Override
-        public void writeTo(BufWriterImpl buf) {
-            DirectCodeBuilder.build(methodInfo, cb -> elements.forEach(cb), constantPool, context, null).writeTo(buf);
-        }
-
         @Override
         public String toString() {
             return String.format("CodeModel[id=%s]", Integer.toHexString(System.identityHashCode(this)));
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedFieldBuilder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedFieldBuilder.java
index 660a999f2a3..d165ddd3928 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedFieldBuilder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedFieldBuilder.java
@@ -24,6 +24,7 @@
  */
 package jdk.internal.classfile.impl;
 
+import java.lang.reflect.AccessFlag;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -50,7 +51,7 @@ public BufferedFieldBuilder(SplitConstantPool constantPool,
         this.context = context;
         this.name = name;
         this.desc = type;
-        this.flags = AccessFlags.ofField();
+        this.flags = new AccessFlagsImpl(AccessFlag.Location.FIELD);
     }
 
     @Override
@@ -78,7 +79,7 @@ public final class Model
             extends AbstractUnboundModel<FieldElement>
             implements FieldModel {
         public Model() {
-            super(elements);
+            super(BufferedFieldBuilder.this.elements);
         }
 
         @Override
@@ -103,7 +104,7 @@ public Utf8Entry fieldType() {
 
         @Override
         public void writeTo(DirectClassBuilder builder) {
-            builder.withField(name, desc, new Consumer<FieldBuilder>() {
+            builder.withField(name, desc, new Consumer<>() {
                 @Override
                 public void accept(FieldBuilder fieldBuilder) {
                     elements.forEach(fieldBuilder);
@@ -111,13 +112,6 @@ public void accept(FieldBuilder fieldBuilder) {
             });
         }
 
-        @Override
-        public void writeTo(BufWriterImpl buf) {
-            DirectFieldBuilder fb = new DirectFieldBuilder(constantPool, context, name, desc, null);
-            elements.forEach(fb);
-            fb.writeTo(buf);
-        }
-
         @Override
         public String toString() {
             return String.format("FieldModel[fieldName=%s, fieldType=%s, flags=%d]", name.stringValue(), desc.stringValue(), flags.flagsMask());
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedMethodBuilder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedMethodBuilder.java
index 880c6717db8..4a9e9b111ce 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedMethodBuilder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/BufferedMethodBuilder.java
@@ -66,7 +66,7 @@ public BufferedMethodBuilder(SplitConstantPool constantPool,
         this.context = context;
         this.name = nameInfo;
         this.desc = typeInfo;
-        this.flags = AccessFlags.ofMethod(flags);
+        this.flags = new AccessFlagsImpl(AccessFlag.Location.METHOD, flags);
         this.original = original;
     }
 
@@ -156,7 +156,7 @@ public final class Model
             extends AbstractUnboundModel<MethodElement>
             implements MethodModel, MethodInfo {
         public Model() {
-            super(elements);
+            super(BufferedMethodBuilder.this.elements);
         }
 
         @Override
@@ -196,7 +196,11 @@ public int parameterSlot(int paramNo) {
 
         @Override
         public Optional<CodeModel> code() {
-            throw new UnsupportedOperationException("nyi");
+            return elements.stream().<CodeModel>mapMulti((e, sink) -> {
+                if (e instanceof CodeModel cm) {
+                    sink.accept(cm);
+                }
+            }).findFirst();
         }
 
         @Override
@@ -209,13 +213,6 @@ public void accept(MethodBuilder mb) {
             });
         }
 
-        @Override
-        public void writeTo(BufWriterImpl buf) {
-            DirectMethodBuilder mb = new DirectMethodBuilder(constantPool, context, name, desc, methodFlags(), null);
-            elements.forEach(mb);
-            mb.writeTo(buf);
-        }
-
         @Override
         public String toString() {
             return String.format("MethodModel[methodName=%s, methodType=%s, flags=%d]",
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/ClassImpl.java b/src/java.base/share/classes/jdk/internal/classfile/impl/ClassImpl.java
index eab283a8c60..c6b9be5c76a 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/ClassImpl.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/ClassImpl.java
@@ -101,7 +101,7 @@ public int classfileLength() {
 
     @Override
     public AccessFlags flags() {
-        return AccessFlags.ofClass(reader.flags());
+        return new AccessFlagsImpl(AccessFlag.Location.CLASS, reader.flags());
     }
 
     @Override
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/CodeImpl.java b/src/java.base/share/classes/jdk/internal/classfile/impl/CodeImpl.java
index 7669cbfdd30..d4719fad0b1 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/CodeImpl.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/CodeImpl.java
@@ -43,7 +43,7 @@
 
 public final class CodeImpl
         extends BoundAttribute.BoundCodeAttribute
-        implements CodeModel, LabelContext {
+        implements LabelContext {
 
     static final Instruction[] SINGLETON_INSTRUCTIONS = new Instruction[256];
 
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
index 536750ebd2f..a7652ac369b 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
@@ -127,12 +127,10 @@ private DirectCodeBuilder(MethodInfo methodInfo,
         this.transformFwdJumps = transformFwdJumps;
         this.transformBackJumps = context.shortJumpsOption() == ClassFile.ShortJumpsOption.FIX_SHORT_JUMPS;
         bytecodesBufWriter = (original instanceof CodeImpl cai) ? new BufWriterImpl(constantPool, context, cai.codeLength())
-                                                               : new BufWriterImpl(constantPool, context);
+                : new BufWriterImpl(constantPool, context);
         this.startLabel = new LabelImpl(this, 0);
         this.endLabel = new LabelImpl(this, -1);
-        this.topLocal = Util.maxLocals(methodInfo.methodFlags(), methodInfo.methodTypeSymbol());
-        if (original != null)
-            this.topLocal = Math.max(this.topLocal, original.maxLocals());
+        this.topLocal = TerminalCodeBuilder.setupTopLocal(methodInfo, original);
     }
 
     @Override
@@ -312,8 +310,9 @@ public void writeBody(BufWriterImpl b) {
 
             private void writeCounters(boolean codeMatch, BufWriterImpl buf) {
                 if (codeMatch) {
-                    buf.writeU2(original.maxStack());
-                    buf.writeU2(original.maxLocals());
+                    var originalAttribute = (CodeImpl) original;
+                    buf.writeU2(originalAttribute.maxStack());
+                    buf.writeU2(originalAttribute.maxLocals());
                 } else {
                     StackCounter cntr = StackCounter.of(DirectCodeBuilder.this, buf);
                     buf.writeU2(cntr.maxStack());
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/FieldImpl.java b/src/java.base/share/classes/jdk/internal/classfile/impl/FieldImpl.java
index ab42b96084a..a71593a5712 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/FieldImpl.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/FieldImpl.java
@@ -24,6 +24,7 @@
  */
 package jdk.internal.classfile.impl;
 
+import java.lang.reflect.AccessFlag;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Consumer;
@@ -48,7 +49,7 @@ public FieldImpl(ClassReader reader, int startPos, int endPos, int attributesPos
 
     @Override
     public AccessFlags flags() {
-        return AccessFlags.ofField(reader.readU2(startPos));
+        return new AccessFlagsImpl(AccessFlag.Location.FIELD, reader.readU2(startPos));
     }
 
     @Override
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/MethodImpl.java b/src/java.base/share/classes/jdk/internal/classfile/impl/MethodImpl.java
index 40223d58d6b..032b18600a8 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/MethodImpl.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/MethodImpl.java
@@ -28,6 +28,7 @@
 import java.lang.classfile.*;
 import java.lang.classfile.constantpool.Utf8Entry;
 
+import java.lang.reflect.AccessFlag;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Consumer;
@@ -51,7 +52,7 @@ public MethodImpl(ClassReader reader, int startPos, int endPos, int attrStart) {
 
     @Override
     public AccessFlags flags() {
-        return AccessFlags.ofMethod(reader.readU2(startPos));
+        return new AccessFlagsImpl(AccessFlag.Location.METHOD, reader.readU2(startPos));
     }
 
     @Override
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java
index 2ea8922d326..d0bf91171ac 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java
@@ -285,5 +285,9 @@ public static record StackMapFrameImpl(int frameType,
                                            List<VerificationTypeInfo> locals,
                                            List<VerificationTypeInfo> stack)
             implements StackMapFrameInfo {
+        public StackMapFrameImpl {
+            locals = List.copyOf(locals);
+            stack = List.copyOf(stack);
+        }
     }
 }
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/TerminalCodeBuilder.java b/src/java.base/share/classes/jdk/internal/classfile/impl/TerminalCodeBuilder.java
index 6e3ca516bf4..054ea919928 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/TerminalCodeBuilder.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/TerminalCodeBuilder.java
@@ -25,8 +25,24 @@
 package jdk.internal.classfile.impl;
 
 import java.lang.classfile.CodeBuilder;
+import java.lang.classfile.CodeModel;
+import java.lang.classfile.attribute.CodeAttribute;
 
 public sealed interface TerminalCodeBuilder extends CodeBuilder, LabelContext
         permits DirectCodeBuilder, BufferedCodeBuilder {
     int curTopLocal();
+
+    static int setupTopLocal(MethodInfo methodInfo, CodeModel original) {
+        int paramSlots = Util.maxLocals(methodInfo.methodFlags(), methodInfo.methodTypeSymbol());
+        if (original == null) {
+            return paramSlots;
+        }
+        if (original instanceof CodeAttribute attr) {
+            return Math.max(paramSlots, attr.maxLocals());
+        }
+        if (original instanceof BufferedCodeBuilder.Model buffered) {
+            return Math.max(paramSlots, buffered.curTopLocal());
+        }
+        throw new InternalError("Unknown code model " + original);
+    }
 }
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/UnboundAttribute.java b/src/java.base/share/classes/jdk/internal/classfile/impl/UnboundAttribute.java
index 6d71497f693..6b64511fd5a 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/UnboundAttribute.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/UnboundAttribute.java
@@ -92,6 +92,8 @@
 import java.lang.classfile.constantpool.PackageEntry;
 import java.lang.classfile.constantpool.Utf8Entry;
 
+import jdk.internal.access.SharedSecrets;
+
 public abstract sealed class UnboundAttribute<T extends Attribute<T>>
         extends AbstractElement
         implements Attribute<T>, Util.Writable {
@@ -627,7 +629,13 @@ public static final class UnboundRuntimeInvisibleParameterAnnotationsAttribute
 
         public UnboundRuntimeInvisibleParameterAnnotationsAttribute(List<List<Annotation>> elements) {
             super(Attributes.runtimeInvisibleParameterAnnotations());
-            this.elements = List.copyOf(elements);
+            // deep copy
+            var array = elements.toArray().clone();
+            for (int i = 0; i < array.length; i++) {
+                array[i] = List.copyOf((List<?>) array[i]);
+            }
+
+            this.elements = SharedSecrets.getJavaUtilCollectionAccess().listFromTrustedArray(array);
         }
 
         @Override
diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/verifier/VerifierImpl.java b/src/java.base/share/classes/jdk/internal/classfile/impl/verifier/VerifierImpl.java
index 33733c5572a..74cdb881a74 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/verifier/VerifierImpl.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/verifier/VerifierImpl.java
@@ -26,6 +26,7 @@
 
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
 import java.lang.classfile.ClassHierarchyResolver;
@@ -133,7 +134,7 @@ public static List<VerifyError> verify(ClassModel classModel, ClassHierarchyReso
                     errors.addAll(inference_verify(klass));
                 }
             }
-            return errors;
+            return Collections.unmodifiableList(errors);
         } finally {
             log_info(logger, "End class verification for: %s", clsName);
         }
diff --git a/src/java.base/share/classes/jdk/internal/misc/VirtualThreads.java b/src/java.base/share/classes/jdk/internal/misc/VirtualThreads.java
deleted file mode 100644
index 04a93afad94..00000000000
--- a/src/java.base/share/classes/jdk/internal/misc/VirtualThreads.java
+++ /dev/null
@@ -1,95 +0,0 @@
-/*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package jdk.internal.misc;
-
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.RejectedExecutionException;
-import jdk.internal.access.JavaLangAccess;
-import jdk.internal.access.SharedSecrets;
-
-/**
- * Defines static methods to support execution in the context of a virtual thread.
- */
-public final class VirtualThreads {
-    private static final JavaLangAccess JLA;
-    static {
-        JLA = SharedSecrets.getJavaLangAccess();
-        if (JLA == null) {
-            throw new InternalError("JavaLangAccess not setup");
-        }
-    }
-    private VirtualThreads() { }
-
-    /**
-     * Parks the current virtual thread until it is unparked or interrupted.
-     * If already unparked then the parking permit is consumed and this method
-     * completes immediately (meaning it doesn't yield). It also completes
-     * immediately if the interrupt status is set.
-     * @throws WrongThreadException if the current thread is not a virtual thread
-     */
-    public static void park() {
-        JLA.parkVirtualThread();
-    }
-
-    /**
-     * Parks the current virtual thread up to the given waiting time or until it
-     * is unparked or interrupted. If already unparked then the parking permit is
-     * consumed and this method completes immediately (meaning it doesn't yield).
-     * It also completes immediately if the interrupt status is set or the waiting
-     * time is {@code <= 0}.
-     * @param nanos the maximum number of nanoseconds to wait
-     * @throws WrongThreadException if the current thread is not a virtual thread
-     */
-    public static void park(long nanos) {
-        JLA.parkVirtualThread(nanos);
-    }
-
-    /**
-     * Parks the current virtual thread until the given deadline or until is is
-     * unparked or interrupted. If already unparked then the parking permit is
-     * consumed and this method completes immediately (meaning it doesn't yield).
-     * It also completes immediately if the interrupt status is set or the
-     * deadline has past.
-     * @param deadline absolute time, in milliseconds, from the epoch
-     * @throws WrongThreadException if the current thread is not a virtual thread
-     */
-    public static void parkUntil(long deadline) {
-        long millis = deadline - System.currentTimeMillis();
-        long nanos = TimeUnit.NANOSECONDS.convert(millis, TimeUnit.MILLISECONDS);
-        park(nanos);
-    }
-
-    /**
-     * Re-enables a virtual thread for scheduling. If the thread was parked then
-     * it will be unblocked, otherwise its next attempt to park will not block
-     * @param thread the virtual thread to unpark
-     * @throws IllegalArgumentException if the thread is not a virtual thread
-     * @throws RejectedExecutionException if the scheduler cannot accept a task
-     */
-    public static void unpark(Thread thread) {
-        JLA.unparkVirtualThread(thread);
-    }
-}
diff --git a/src/java.base/share/classes/jdk/internal/util/DecimalDigits.java b/src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
index ea1c9fec730..83438e59b82 100644
--- a/src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
+++ b/src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
@@ -110,4 +110,30 @@ public static int stringSize(int x) {
         }
         return 10 + d;
     }
+
+    /**
+     * Returns the string representation size for a given long value.
+     *
+     * @param x long value
+     * @return string size
+     *
+     * @implNote There are other ways to compute this: e.g. binary search,
+     * but values are biased heavily towards zero, and therefore linear search
+     * wins. The iteration results are also routinely inlined in the generated
+     * code after loop unrolling.
+     */
+    public static int stringSize(long x) {
+        int d = 1;
+        if (x >= 0) {
+            d = 0;
+            x = -x;
+        }
+        long p = -10;
+        for (int i = 1; i < 19; i++) {
+            if (x > p)
+                return i + d;
+            p = 10 * p;
+        }
+        return 19 + d;
+    }
 }
diff --git a/src/java.base/share/classes/sun/security/util/DerInputStream.java b/src/java.base/share/classes/sun/security/util/DerInputStream.java
index 8df4e80eb97..e0519f0fa09 100644
--- a/src/java.base/share/classes/sun/security/util/DerInputStream.java
+++ b/src/java.base/share/classes/sun/security/util/DerInputStream.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -114,7 +114,7 @@ public DerValue getDerValue() throws IOException {
             // to the end of return value by DerIndefLenConverter::convertBytes
             // and stay inside result.buffer.
             int unused = result.buffer.length - result.end;
-            this.pos = this.data.length - unused;
+            this.pos = this.end - unused;
         } else {
             this.pos = result.end;
         }
diff --git a/src/java.base/windows/classes/sun/nio/fs/WindowsSecurity.java b/src/java.base/windows/classes/sun/nio/fs/WindowsSecurity.java
index 19e3e62412b..9bcd800e13c 100644
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsSecurity.java
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsSecurity.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,8 +25,8 @@
 
 package sun.nio.fs;
 
-import jdk.internal.misc.PreviewFeatures;
 import jdk.internal.vm.Continuation;
+import jdk.internal.vm.ContinuationSupport;
 
 import static sun.nio.fs.WindowsNativeDispatcher.*;
 import static sun.nio.fs.WindowsConstants.*;
@@ -106,7 +106,7 @@ static Privilege enablePrivilege(String priv) {
         final boolean needToRevert = elevated;
 
         // prevent yielding with privileges
-        if (PreviewFeatures.isEnabled())
+        if (ContinuationSupport.isSupported())
             Continuation.pin();
 
         return () -> {
@@ -126,7 +126,7 @@ else if (needToRevert)
                 }
             } finally {
                 LocalFree(pLuid);
-                if (PreviewFeatures.isEnabled())
+                if (ContinuationSupport.isSupported())
                     Continuation.unpin();
             }
         };
diff --git a/src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java b/src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java
index e643d3d28ff..5d77800f88e 100644
--- a/src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java
+++ b/src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java
@@ -610,10 +610,10 @@ public void paintPopupMenuBackground(SynthContext context, Graphics g,
                 x + insets.left, y + insets.top, w - insets.left - insets.right,
                 h - insets.top - insets.bottom);
             BufferedImage img = ENGINE.finishPainting();
-            if(!isHW) {
+            if (!isHW && img != null) {
                 int border = img.getRGB(0, h / 2);
-                if (img != null && border == img.getRGB(w / 2, h / 2)) {
-                    // fix no menu borders in Adwaita theme
+                if (border == img.getRGB(w / 2, h / 2)) {
+                    // fix no menu borders
                     Graphics g2 = img.getGraphics();
                     Color c = new Color(border);
                     g2.setColor(new Color(Math.max((int) (c.getRed() * 0.8), 0),
diff --git a/src/java.desktop/share/classes/javax/swing/text/html/CSS.java b/src/java.desktop/share/classes/javax/swing/text/html/CSS.java
index 595799926a3..8239565a53f 100644
--- a/src/java.desktop/share/classes/javax/swing/text/html/CSS.java
+++ b/src/java.desktop/share/classes/javax/swing/text/html/CSS.java
@@ -844,6 +844,10 @@ Object getInternalCSSValue(CSS.Attribute key, String value) {
     }
 
     static Object mergeTextDecoration(String value) {
+        if (value.startsWith("none")) {
+            return null;
+        }
+
         boolean underline = value.contains("underline");
         boolean strikeThrough = value.contains("line-through");
         if (!underline && !strikeThrough) {
diff --git a/src/java.desktop/share/classes/javax/swing/text/html/StyleSheet.java b/src/java.desktop/share/classes/javax/swing/text/html/StyleSheet.java
index 0790060f5e8..9b8e33b4c6b 100644
--- a/src/java.desktop/share/classes/javax/swing/text/html/StyleSheet.java
+++ b/src/java.desktop/share/classes/javax/swing/text/html/StyleSheet.java
@@ -2391,7 +2391,7 @@ void drawShape(Graphics g, CSS.Value type, int ax, int ay, int aw,
             // Position shape to the middle of the html text.
             int gap = isLeftToRight ? - (bulletgap + size/3) : (aw + bulletgap);
             int x = ax + gap;
-            int y = Math.max(ay, ay + (int)Math.ceil(ah/2));
+            int y = Math.max(ay, ay + ah/2);
 
             if (type == CSS.Value.SQUARE) {
                 g.drawRect(x, y, size/3, size/3);
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
index 28768f2517b..8576d8cfb2f 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
@@ -62,6 +62,8 @@
 import static com.sun.tools.javac.code.Type.*;
 import static com.sun.tools.javac.code.TypeTag.*;
 import static com.sun.tools.javac.jvm.ClassFile.externalize;
+import static com.sun.tools.javac.main.Option.DOE;
+
 import com.sun.tools.javac.resources.CompilerProperties.Fragments;
 
 /**
@@ -99,6 +101,7 @@ public class Types {
     final Name capturedName;
 
     public final Warner noWarnings;
+    public final boolean dumpStacktraceOnError;
 
     // <editor-fold defaultstate="collapsed" desc="Instantiating">
     public static Types instance(Context context) {
@@ -120,6 +123,8 @@ protected Types(Context context) {
         messages = JavacMessages.instance(context);
         diags = JCDiagnostic.Factory.instance(context);
         noWarnings = new Warner(null);
+        Options options = Options.instance(context);
+        dumpStacktraceOnError = options.isSet("dev") || options.isSet(DOE);
     }
     // </editor-fold>
 
@@ -634,12 +639,13 @@ public boolean isConvertible(Type t, Type s) {
      * wraps a diagnostic that can be used to generate more details error
      * messages.
      */
-    public static class FunctionDescriptorLookupError extends RuntimeException {
+    public static class FunctionDescriptorLookupError extends CompilerInternalException {
         private static final long serialVersionUID = 0;
 
         transient JCDiagnostic diagnostic;
 
-        FunctionDescriptorLookupError() {
+        FunctionDescriptorLookupError(boolean dumpStackTraceOnError) {
+            super(dumpStackTraceOnError);
             this.diagnostic = null;
         }
 
@@ -651,12 +657,6 @@ FunctionDescriptorLookupError setMessage(JCDiagnostic diag) {
         public JCDiagnostic getDiagnostic() {
             return diagnostic;
         }
-
-        @Override
-        public Throwable fillInStackTrace() {
-            // This is an internal exception; the stack trace is irrelevant.
-            return this;
-        }
     }
 
     /**
@@ -809,7 +809,7 @@ FunctionDescriptorLookupError failure(String msg, Object... args) {
         }
 
         FunctionDescriptorLookupError failure(JCDiagnostic diag) {
-            return new FunctionDescriptorLookupError().setMessage(diag);
+            return new FunctionDescriptorLookupError(Types.this.dumpStacktraceOnError).setMessage(diag);
         }
     }
 
@@ -5107,41 +5107,30 @@ public RetentionPolicy getRetention(TypeSymbol sym) {
 
     // <editor-fold defaultstate="collapsed" desc="Signature Generation">
 
-    public abstract static class SignatureGenerator {
+    public abstract class SignatureGenerator {
 
-        public static class InvalidSignatureException extends RuntimeException {
+        public class InvalidSignatureException extends CompilerInternalException {
             private static final long serialVersionUID = 0;
 
             private final transient Type type;
 
-            InvalidSignatureException(Type type) {
+            InvalidSignatureException(Type type, boolean dumpStackTraceOnError) {
+                super(dumpStackTraceOnError);
                 this.type = type;
             }
 
             public Type type() {
                 return type;
             }
-
-            @Override
-            public Throwable fillInStackTrace() {
-                // This is an internal exception; the stack trace is irrelevant.
-                return this;
-            }
         }
 
-        private final Types types;
-
         protected abstract void append(char ch);
         protected abstract void append(byte[] ba);
         protected abstract void append(Name name);
         protected void classReference(ClassSymbol c) { /* by default: no-op */ }
 
-        protected SignatureGenerator(Types types) {
-            this.types = types;
-        }
-
         protected void reportIllegalSignature(Type t) {
-            throw new InvalidSignatureException(t);
+            throw new InvalidSignatureException(t, Types.this.dumpStacktraceOnError);
         }
 
         /**
@@ -5257,9 +5246,9 @@ public void assembleClassSig(Type type) {
             if (outer.allparams().nonEmpty()) {
                 boolean rawOuter =
                         c.owner.kind == MTH || // either a local class
-                        c.name == types.names.empty; // or anonymous
+                        c.name == Types.this.names.empty; // or anonymous
                 assembleClassSig(rawOuter
-                        ? types.erasure(outer)
+                        ? Types.this.erasure(outer)
                         : outer);
                 append(rawOuter ? '$' : '.');
                 Assert.check(c.flatname.startsWith(c.owner.enclClass().flatname));
@@ -5281,7 +5270,7 @@ public void assembleParamsSig(List<Type> typarams) {
             for (List<Type> ts = typarams; ts.nonEmpty(); ts = ts.tail) {
                 Type.TypeVar tvar = (Type.TypeVar) ts.head;
                 append(tvar.tsym.name);
-                List<Type> bounds = types.getBounds(tvar);
+                List<Type> bounds = Types.this.getBounds(tvar);
                 if ((bounds.head.tsym.flags() & INTERFACE) != 0) {
                     append(':');
                 }
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Annotate.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Annotate.java
index 48459dd96bb..77a7e3332f0 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Annotate.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Annotate.java
@@ -945,7 +945,13 @@ private MethodSymbol validateContainer(Type targetContainerType,
         boolean fatalError = false;
 
         // Validate that there is a (and only 1) value method
-        Scope scope = targetContainerType.tsym.members();
+        Scope scope = null;
+        try {
+            scope = targetContainerType.tsym.members();
+        } catch (CompletionFailure ex) {
+            chk.completionError(pos, ex);
+            return null;
+        }
         int nr_value_elems = 0;
         boolean error = false;
         for(Symbol elm : scope.getSymbolsByName(names.value)) {
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java
index e3e7e1adea5..f5df6adddf3 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Infer.java
@@ -47,6 +47,7 @@
 import com.sun.tools.javac.comp.Infer.GraphSolver.InferenceGraph.Node;
 import com.sun.tools.javac.comp.Resolve.InapplicableMethodException;
 import com.sun.tools.javac.comp.Resolve.VerboseResolutionMode;
+import com.sun.tools.javac.util.CompilerInternalException;
 
 import java.io.IOException;
 import java.io.Writer;
@@ -68,7 +69,7 @@
 import java.util.function.Predicate;
 
 import static com.sun.tools.javac.code.TypeTag.*;
-import java.util.Comparator;
+import static com.sun.tools.javac.main.Option.DOE;
 
 /** Helper class for type parameter inference, used by the attribution phase.
  *
@@ -97,6 +98,8 @@ public class Infer {
      */
     private List<String> pendingGraphs;
 
+    private final boolean dumpStacktraceOnError;
+
     public static Infer instance(Context context) {
         Infer instance = context.get(inferKey);
         if (instance == null)
@@ -119,6 +122,7 @@ protected Infer(Context context) {
         pendingGraphs = List.nil();
 
         emptyContext = new InferenceContext(this, List.nil());
+        dumpStacktraceOnError = options.isSet("dev") || options.isSet(DOE);
     }
 
     /** A value for prototypes that admit any type, including polymorphic ones. */
@@ -133,8 +137,8 @@ public static class InferenceException extends InapplicableMethodException {
 
         transient List<JCDiagnostic> messages = List.nil();
 
-        InferenceException() {
-            super(null);
+        InferenceException(boolean dumpStacktrace) {
+            super(null, dumpStacktrace);
         }
 
         @Override
@@ -144,7 +148,7 @@ public JCDiagnostic getDiagnostic() {
     }
 
     InferenceException error(JCDiagnostic diag) {
-        InferenceException result = new InferenceException();
+        InferenceException result = new InferenceException(dumpStacktraceOnError);
         if (diag != null) {
             result.messages = result.messages.append(diag);
         }
@@ -1342,20 +1346,15 @@ interface GraphStrategy {
          * A NodeNotFoundException is thrown whenever an inference strategy fails
          * to pick the next node to solve in the inference graph.
          */
-        public static class NodeNotFoundException extends RuntimeException {
+        class NodeNotFoundException extends CompilerInternalException {
             private static final long serialVersionUID = 0;
 
             transient InferenceGraph graph;
 
-            public NodeNotFoundException(InferenceGraph graph) {
+            public NodeNotFoundException(InferenceGraph graph, boolean dumpStacktraceOnError) {
+                super(dumpStacktraceOnError);
                 this.graph = graph;
             }
-
-            @Override
-            public Throwable fillInStackTrace() {
-                // This is an internal exception; the stack trace is irrelevant.
-                return this;
-            }
         }
         /**
          * Pick the next node (leaf) to solve in the graph
@@ -1375,7 +1374,7 @@ abstract class LeafSolver implements GraphStrategy {
         public Node pickNode(InferenceGraph g) {
             if (g.nodes.isEmpty()) {
                 //should not happen
-                throw new NodeNotFoundException(g);
+                throw new NodeNotFoundException(g, Infer.this.dumpStacktraceOnError);
             }
             return g.nodes.get(0);
         }
@@ -1450,7 +1449,7 @@ public Node pickNode(final InferenceGraph g) {
             }
             if (bestPath == noPath) {
                 //no path leads there
-                throw new NodeNotFoundException(g);
+                throw new NodeNotFoundException(g, Infer.this.dumpStacktraceOnError);
             }
             return bestPath.fst.head;
         }
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java
index 7f1ad8211cb..2c3d79c0ab6 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java
@@ -1796,7 +1796,7 @@ private class L2MSignatureGenerator extends Types.SignatureGenerator {
         boolean allowIllegalSignatures;
 
         L2MSignatureGenerator(boolean allowIllegalSignatures) {
-            super(types);
+            types.super();
             this.allowIllegalSignatures = allowIllegalSignatures;
         }
 
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
index a330f045fe5..c5fd2177d49 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
@@ -62,6 +62,7 @@
 import com.sun.tools.javac.tree.JCTree.JCCase;
 import com.sun.tools.javac.tree.JCTree.JCExpression;
 import com.sun.tools.javac.tree.JCTree.JCExpressionStatement;
+
 import static com.sun.tools.javac.tree.JCTree.JCOperatorExpression.OperandPos.LEFT;
 import com.sun.tools.javac.tree.JCTree.JCSwitchExpression;
 
@@ -2629,7 +2630,7 @@ private class LowerSignatureGenerator extends Types.SignatureGenerator {
         StringBuilder sb = new StringBuilder();
 
         LowerSignatureGenerator() {
-            super(types);
+            types.super();
         }
 
         @Override
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
index 643bb22c853..c71b6d341dc 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
@@ -79,6 +79,7 @@
 import static com.sun.tools.javac.code.Kinds.Kind.*;
 import static com.sun.tools.javac.code.TypeTag.*;
 import static com.sun.tools.javac.comp.Resolve.MethodResolutionPhase.*;
+import static com.sun.tools.javac.main.Option.DOE;
 import static com.sun.tools.javac.tree.JCTree.Tag.*;
 import static com.sun.tools.javac.util.Iterators.createCompoundIterator;
 
@@ -112,6 +113,7 @@ public class Resolve {
     private final boolean allowYieldStatement;
     final EnumSet<VerboseResolutionMode> verboseResolutionMode;
     final boolean dumpMethodReferenceSearchResults;
+    final boolean dumpStacktraceOnError;
 
     WriteableScope polymorphicSignatureScope;
 
@@ -149,6 +151,7 @@ protected Resolve(Context context) {
         allowModules = Feature.MODULES.allowedInSource(source);
         allowRecords = Feature.RECORDS.allowedInSource(source);
         dumpMethodReferenceSearchResults = options.isSet("debug.dumpMethodReferenceSearchResults");
+        dumpStacktraceOnError = options.isSet("dev") || options.isSet(DOE);
     }
 
     /** error symbols, which are returned when resolution fails
@@ -584,7 +587,7 @@ Type rawInstantiate(Env<AttrContext> env,
             ForAll pmt = (ForAll) mt;
             if (typeargtypes.length() != pmt.tvars.length())
                  // not enough args
-                throw new InapplicableMethodException(diags.fragment(Fragments.WrongNumberTypeArgs(Integer.toString(pmt.tvars.length()))));
+                throw new InapplicableMethodException(diags.fragment(Fragments.WrongNumberTypeArgs(Integer.toString(pmt.tvars.length()))), dumpStacktraceOnError);
             // Check type arguments are within bounds
             List<Type> formals = pmt.tvars;
             List<Type> actuals = typeargtypes;
@@ -593,7 +596,7 @@ Type rawInstantiate(Env<AttrContext> env,
                                                 pmt.tvars, typeargtypes);
                 for (; bounds.nonEmpty(); bounds = bounds.tail) {
                     if (!types.isSubtypeUnchecked(actuals.head, bounds.head, warn)) {
-                        throw new InapplicableMethodException(diags.fragment(Fragments.ExplicitParamDoNotConformToBounds(actuals.head, bounds)));
+                        throw new InapplicableMethodException(diags.fragment(Fragments.ExplicitParamDoNotConformToBounds(actuals.head, bounds)), dumpStacktraceOnError);
                     }
                 }
                 formals = formals.tail;
@@ -830,7 +833,7 @@ protected void reportMC(DiagnosticPosition pos, MethodCheckDiag diag, InferenceC
             String key = inferDiag ? diag.inferKey : diag.basicKey;
             throw inferDiag ?
                 infer.error(diags.create(DiagnosticType.FRAGMENT, log.currentSource(), pos, key, args)) :
-                methodCheckFailure.setMessage(diags.create(DiagnosticType.FRAGMENT, log.currentSource(), pos, key, args));
+                getMethodCheckFailure().setMessage(diags.create(DiagnosticType.FRAGMENT, log.currentSource(), pos, key, args));
         }
 
         /**
@@ -842,7 +845,7 @@ class SharedInapplicableMethodException extends InapplicableMethodException {
             private static final long serialVersionUID = 0;
 
             SharedInapplicableMethodException() {
-                super(null);
+                super(null, Resolve.this.dumpStacktraceOnError);
             }
 
             SharedInapplicableMethodException setMessage(JCDiagnostic details) {
@@ -851,12 +854,15 @@ SharedInapplicableMethodException setMessage(JCDiagnostic details) {
             }
         }
 
-        SharedInapplicableMethodException methodCheckFailure = new SharedInapplicableMethodException();
+        private SharedInapplicableMethodException methodCheckFailure;
 
         public MethodCheck mostSpecificCheck(List<Type> actuals) {
             return nilMethodCheck;
         }
 
+        private SharedInapplicableMethodException getMethodCheckFailure() {
+            return methodCheckFailure == null ? methodCheckFailure = new SharedInapplicableMethodException() : methodCheckFailure;
+        }
     }
 
     /**
@@ -1036,7 +1042,7 @@ public boolean compatible(Type found, Type req, Warner warn) {
         }
 
         public void report(DiagnosticPosition pos, JCDiagnostic details) {
-            throw new InapplicableMethodException(details);
+            throw new InapplicableMethodException(details, Resolve.this.dumpStacktraceOnError);
         }
 
         public Warner checkWarner(DiagnosticPosition pos, Type found, Type req) {
@@ -1392,24 +1398,19 @@ public MethodCheck mostSpecificCheck(List<Type> actuals) {
         }
     }
 
-    public static class InapplicableMethodException extends RuntimeException {
+    public static class InapplicableMethodException extends CompilerInternalException {
         private static final long serialVersionUID = 0;
 
         transient JCDiagnostic diagnostic;
 
-        InapplicableMethodException(JCDiagnostic diag) {
+        InapplicableMethodException(JCDiagnostic diag, boolean dumpStackTraceOnError) {
+            super(dumpStackTraceOnError);
             this.diagnostic = diag;
         }
 
         public JCDiagnostic getDiagnostic() {
             return diagnostic;
         }
-
-        @Override
-        public Throwable fillInStackTrace() {
-            // This is an internal exception; the stack trace is irrelevant.
-            return this;
-        }
     }
 
 /* ***************************************************************************
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java
index 2d522d01641..f1f4e73b5a6 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java
@@ -79,6 +79,7 @@
 import com.sun.tools.javac.code.Type;
 import static com.sun.tools.javac.code.TypeTag.BOT;
 import static com.sun.tools.javac.code.TypeTag.VOID;
+
 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant;
 import com.sun.tools.javac.jvm.Target;
 import com.sun.tools.javac.tree.JCTree;
@@ -786,7 +787,7 @@ private class PrimitiveGenerator extends Types.SignatureGenerator {
         StringBuilder sb = new StringBuilder();
 
         PrimitiveGenerator() {
-            super(types);
+            types.super();
         }
 
         @Override
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/PoolWriter.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/PoolWriter.java
index af6f4b67fae..bfdb9775e11 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/PoolWriter.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/PoolWriter.java
@@ -100,7 +100,7 @@ public class PoolWriter {
     public PoolWriter(Types types, Names names) {
         this.types = types;
         this.names = names;
-        this.signatureGen = new SharedSignatureGenerator(types);
+        this.signatureGen = new SharedSignatureGenerator();
         this.pool = new WriteablePoolHelper();
     }
 
@@ -278,8 +278,8 @@ class SharedSignatureGenerator extends Types.SignatureGenerator {
          */
         ByteBuffer sigbuf = new ByteBuffer();
 
-        SharedSignatureGenerator(Types types) {
-            super(types);
+        SharedSignatureGenerator() {
+            types.super();
         }
 
         /**
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/util/CompilerInternalException.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/util/CompilerInternalException.java
new file mode 100644
index 00000000000..3d3c45368c2
--- /dev/null
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/util/CompilerInternalException.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.tools.javac.util;
+
+/** The super class of all compiler internal exceptions
+ *
+ *  <p><b>This is NOT part of any supported API.
+ *  If you write code that depends on this, you do so at your own risk.
+ *  This code and its internal interfaces are subject to change or
+ *  deletion without notice.</b>
+ */
+public class CompilerInternalException extends RuntimeException {
+    private static final long serialVersionUID = 0;
+
+    @SuppressWarnings("this-escape")
+    public CompilerInternalException(boolean dumpStackTraceOnError) {
+        /* by default the stacktrace wont be filled, meaning that method CompilerInternalException::fillInStackTrace
+         * will always be invoked, if we do want to dump the stacktrace then we will invoke super::fillInStackTrace
+         * there is a bit of a dance here that could be fixed once flexible constructor bodies exits the preview
+         * state
+         */
+        if (dumpStackTraceOnError) {
+            super.fillInStackTrace();
+        }
+    }
+
+    @Override
+    public Throwable fillInStackTrace() {
+        return this;
+    }
+}
diff --git a/src/jdk.internal.jvmstat/share/classes/sun/jvmstat/perfdata/resources/aliasmap b/src/jdk.internal.jvmstat/share/classes/sun/jvmstat/perfdata/resources/aliasmap
index 5993acf701f..001ce5b5cac 100644
--- a/src/jdk.internal.jvmstat/share/classes/sun/jvmstat/perfdata/resources/aliasmap
+++ b/src/jdk.internal.jvmstat/share/classes/sun/jvmstat/perfdata/resources/aliasmap
@@ -404,8 +404,6 @@ alias sun.gc.lastCause                            // 1.5.0 b39
         hotspot.gc.last_cause                     // 1.4.2_02
 
 // sun.gc.policy
-alias sun.gc.policy.avgBaseFootprint              // 1.5.0 b39
-	hotspot.gc.policy.avg_base_footprint      // 1.5.0 b21
 alias sun.gc.policy.avgMajorIntervalTime          // 1.5.0 b39
 	hotspot.gc.policy.avg_major_interval      // 1.5.0 b21
 alias sun.gc.policy.avgMajorPauseTime             // 1.5.0 b39
diff --git a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java
index 14646fd0275..59369754526 100644
--- a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java
+++ b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java
@@ -289,6 +289,12 @@ HotSpotResolvedJavaType lookupType(ClassLoader classLoader, String name) throws
 
     native HotSpotResolvedJavaType lookupJClass(long jclass);
 
+    /**
+     * Gets the {@code jobject} value wrapped by {@code peerObject}.
+     * Must not be called if {@link Services#IS_IN_NATIVE_IMAGE} is {@code false}.
+     */
+    native long getJObjectValue(HotSpotObjectConstantImpl peerObject);
+
     /**
      * Resolves the entry at index {@code cpi} in {@code constantPool} to an interned String object.
      *
diff --git a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java
index 3dcf855ff23..3fd92f8dee5 100644
--- a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java
+++ b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java
@@ -925,23 +925,23 @@ JavaType lookupTypeInternal(String name, HotSpotResolvedObjectType accessingType
     }
 
     /**
-     * Gets the {@code jobject} value wrapped by {@code peerObject}. The returned "naked" value is
-     * only valid as long as {@code peerObject} is valid. Note that the latter may be shorter than
-     * the lifetime of {@code peerObject}. As such, this method should only be used to pass an
-     * object parameter across a JNI call from the JVMCI shared library to HotSpot. This method must
-     * only be called from within the JVMCI shared library.
+     * Gets the {@code jobject} value wrapped by {@code peerObject}. The returned value is
+     * a JNI local reference whose lifetime is scoped by the nearest Java caller (from
+     * HotSpot's perspective). You can use {@code PushLocalFrame} and {@code PopLocalFrame} to
+     * shorten the lifetime of the reference. The current thread's state must be
+     * {@code _thread_in_native}. A call from the JVMCI shared library (e.g. libgraal) is in such
+     * a state.
      *
-     * @param peerObject a reference to an object in the peer runtime
-     * @return the {@code jobject} value wrapped by {@code peerObject}
+     * @param peerObject a reference to an object in the HotSpot heap
+     * @return the {@code jobject} value unpacked from {@code peerObject}
      * @throws IllegalArgumentException if the current runtime is not the JVMCI shared library or
-     *             {@code peerObject} is not a peer object reference
+     *             {@code peerObject} is not a HotSpot heap object reference
+     * @throws IllegalStateException if not called from within the JVMCI shared library
+     *         or if there is no Java caller frame on the stack
+     *         (i.e., JavaThread::has_last_Java_frame returns false)
      */
     public long getJObjectValue(HotSpotObjectConstant peerObject) {
-        if (peerObject instanceof IndirectHotSpotObjectConstantImpl) {
-            IndirectHotSpotObjectConstantImpl remote = (IndirectHotSpotObjectConstantImpl) peerObject;
-            return remote.getHandle();
-        }
-        throw new IllegalArgumentException("Cannot get jobject value for " + peerObject + " (" + peerObject.getClass().getName() + ")");
+        return compilerToVm.getJObjectValue((HotSpotObjectConstantImpl)peerObject);
     }
 
     @Override
diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractExecutableMemberWriter.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractExecutableMemberWriter.java
index 4e929130b66..f6ad4cf05df 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractExecutableMemberWriter.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractExecutableMemberWriter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -31,6 +31,7 @@
 import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.TypeParameterElement;
 import javax.lang.model.element.VariableElement;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.ExecutableType;
@@ -130,6 +131,24 @@ protected void addInheritedSummaryLink(TypeElement te, Element member, Content t
         target.add(writer.getDocLink(PLAIN, te, member, name(member)));
     }
 
+    /**
+     * Adds the generic type parameters.
+     *
+     * @param member the member to add the generic type parameters for
+     * @param target the content to which the generic type parameters will be added
+     */
+    protected void addTypeParameters(ExecutableElement member, Content target) {
+        Content typeParameters = getTypeParameters(member);
+        target.add(typeParameters);
+        // Add explicit line break between method type parameters and
+        // return type in member summary table to avoid random wrapping.
+        if (typeParameters.charCount() > 10) {
+            target.add(new HtmlTree(TagName.BR));
+        } else {
+            target.add(Entity.NO_BREAK_SPACE);
+        }
+    }
+
     /**
      * Add the parameter for the executable member.
      *
diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractMemberWriter.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractMemberWriter.java
index caeb6c35e6d..af1f7ef1fe6 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractMemberWriter.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/AbstractMemberWriter.java
@@ -466,16 +466,8 @@ protected void addModifiersAndType(Element member, TypeMirror type,
                     ? ((ExecutableElement)member).getTypeParameters()
                     : null;
             if (list != null && !list.isEmpty()) {
-                Content typeParameters = ((AbstractExecutableMemberWriter) this)
-                        .getTypeParameters((ExecutableElement)member);
-                code.add(typeParameters);
-                // Add explicit line break between method type parameters and
-                // return type in member summary table to avoid random wrapping.
-                if (typeParameters.charCount() > 10) {
-                    code.add(new HtmlTree(TagName.BR));
-                } else {
-                    code.add(Entity.NO_BREAK_SPACE);
-                }
+                ((AbstractExecutableMemberWriter) this)
+                  .addTypeParameters((ExecutableElement)member, code);
             }
             code.add(
                     writer.getLink(new HtmlLinkInfo(configuration,
diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ClassUseWriter.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ClassUseWriter.java
index e949b4ddc68..94e66f1eed6 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ClassUseWriter.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ClassUseWriter.java
@@ -142,7 +142,7 @@ public ClassUseWriter(HtmlConfiguration configuration,
 
         methodSubWriter = new MethodWriter(this);
         constrSubWriter = new ConstructorWriter(this);
-        constrSubWriter.setFoundNonPubConstructor(true);
+        constrSubWriter.setShowConstructorModifiers(true);
         fieldSubWriter = new FieldWriter(this);
         classSubWriter = new NestedClassWriter(this);
     }
diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ConstructorWriter.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ConstructorWriter.java
index 1c4af2faf97..c5fb332a008 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ConstructorWriter.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/ConstructorWriter.java
@@ -31,6 +31,7 @@
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.TypeParameterElement;
 
 import jdk.javadoc.internal.doclets.formats.html.markup.ContentBuilder;
 import jdk.javadoc.internal.doclets.formats.html.markup.Entity;
@@ -53,7 +54,17 @@ public class ConstructorWriter extends AbstractExecutableMemberWriter {
      */
     private ExecutableElement currentConstructor;
 
-    private boolean foundNonPubConstructor = false;
+    /**
+     * If any constructors are non-public, then we want the modifiers shown in the summary.
+     * This implies we need a three-column summary.
+     */
+    private boolean showConstructorModifiers = false;
+
+    /**
+     * Whether any constructors have type parameters.
+     * This implies we need a three column summary.
+     */
+    private boolean hasTypeParamsConstructor = false;
 
     /**
      * Construct a new member writer for constructors.
@@ -65,11 +76,7 @@ public ConstructorWriter(ClassWriter writer) {
 
         // the following must be done before the summary table is generated
         var constructors = getVisibleMembers(VisibleMemberTable.Kind.CONSTRUCTORS);
-        for (Element constructor : constructors) {
-            if (utils.isProtected(constructor) || utils.isPrivate(constructor)) {
-                setFoundNonPubConstructor(true);
-            }
-        }
+        analyzeConstructors(constructors);
     }
 
     /**
@@ -94,11 +101,7 @@ public void buildDetails(Content target) {
     protected void buildConstructorDoc(Content target) {
         var constructors = getVisibleMembers(VisibleMemberTable.Kind.CONSTRUCTORS);
         if (!constructors.isEmpty()) {
-            for (Element constructor : constructors) {
-                if (utils.isProtected(constructor) || utils.isPrivate(constructor)) {
-                    setFoundNonPubConstructor(true);
-                }
-            }
+            analyzeConstructors(constructors);
 
             Content constructorDetailsHeader = getConstructorDetailsHeader(target);
             Content memberList = getMemberList();
@@ -126,6 +129,24 @@ protected void buildConstructorDoc(Content target) {
         }
     }
 
+    // Calculate "showConstructorModifiers" and "hasTypeParamsConstructor"
+    private void analyzeConstructors(List<? extends Element> constructors) {
+        for (Element constructor : constructors) {
+            if (utils.isProtected(constructor) || utils.isPrivate(constructor)) {
+                setShowConstructorModifiers(true);
+            }
+            List<? extends TypeParameterElement> list = ((ExecutableElement)constructor).getTypeParameters();
+            if (list != null && !list.isEmpty()) {
+                hasTypeParamsConstructor = true;
+            }
+        }
+    }
+
+    // Does the constructor summary need three columnns or just two?
+    protected boolean threeColumnSummary() {
+        return showConstructorModifiers || hasTypeParamsConstructor;
+    }
+
     @Override
     protected void buildSignature(Content target) {
         target.add(getSignature(currentConstructor));
@@ -201,6 +222,7 @@ protected Content getConstructorHeaderContent(ExecutableElement constructor) {
 
     protected Content getSignature(ExecutableElement constructor) {
         return new Signatures.MemberSignature(constructor, this)
+                .setTypeParameters(getTypeParameters(constructor))
                 .setParameters(getParameters(constructor, true))
                 .setExceptions(getExceptions(constructor))
                 .setAnnotations(writer.getAnnotationInfo(constructor, true))
@@ -231,8 +253,8 @@ protected Content getConstructorDetails(Content memberDetailsHeader, Content mem
                         .add(memberDetails));
     }
 
-    protected void setFoundNonPubConstructor(boolean foundNonPubConstructor) {
-        this.foundNonPubConstructor = foundNonPubConstructor;
+    protected void setShowConstructorModifiers(boolean showConstructorModifiers) {
+        this.showConstructorModifiers = showConstructorModifiers;
     }
 
     @Override
@@ -244,7 +266,7 @@ public void addSummaryLabel(Content content) {
 
     @Override
     public TableHeader getSummaryTableHeader(Element member) {
-        if (foundNonPubConstructor) {
+        if (threeColumnSummary()) {
             return new TableHeader(contents.modifierLabel, contents.constructorLabel,
                     contents.descriptionLabel);
         } else {
@@ -256,7 +278,7 @@ public TableHeader getSummaryTableHeader(Element member) {
     protected Table<Element> createSummaryTable() {
         List<HtmlStyle> bodyRowStyles;
 
-        if (foundNonPubConstructor) {
+        if (threeColumnSummary()) {
             bodyRowStyles = Arrays.asList(HtmlStyle.colFirst, HtmlStyle.colConstructorName,
                     HtmlStyle.colLast);
         } else {
@@ -276,7 +298,7 @@ public void addInheritedSummaryLabel(TypeElement typeElement, Content content) {
 
     @Override
     protected void addSummaryType(Element member, Content content) {
-        if (foundNonPubConstructor) {
+        if (threeColumnSummary()) {
             var code = new HtmlTree(TagName.CODE);
             if (utils.isProtected(member)) {
                 code.add("protected ");
@@ -288,6 +310,11 @@ protected void addSummaryType(Element member, Content content) {
                 code.add(
                         resources.getText("doclet.Package_private"));
             }
+            ExecutableElement constructor = (ExecutableElement)member;
+            List<? extends TypeParameterElement> list = constructor.getTypeParameters();
+            if (list != null && !list.isEmpty()) {
+                addTypeParameters(constructor, code);
+            }
             content.add(code);
         }
     }
diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Signatures.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Signatures.java
index f4f472de9f9..afc0648fa79 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Signatures.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Signatures.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -529,6 +529,7 @@ private void appendModifiers(Content target) {
         private int appendTypeParameters(Content target, int lastLineSeparator) {
             // Apply different wrapping strategies for type parameters
             // depending on the combined length of type parameters and return type.
+            // Note return type will be null if this is a constructor.
             int typeParamLength = typeParameters.charCount();
 
             if (typeParamLength >= TYPE_PARAMS_MAX_INLINE_LENGTH) {
@@ -539,9 +540,10 @@ private int appendTypeParameters(Content target, int lastLineSeparator) {
 
             int lineLength = target.charCount() - lastLineSeparator;
             int newLastLineSeparator = lastLineSeparator;
+            int returnTypeLength = returnType != null ? returnType.charCount() : 0;
 
             // sum below includes length of modifiers plus type params added above
-            if (lineLength + returnType.charCount() > RETURN_TYPE_MAX_LINE_LENGTH) {
+            if (lineLength + returnTypeLength > RETURN_TYPE_MAX_LINE_LENGTH) {
                 target.add(Text.NL);
                 newLastLineSeparator = target.charCount();
             } else {
diff --git a/src/jdk.jdeps/share/classes/com/sun/tools/javap/ClassWriter.java b/src/jdk.jdeps/share/classes/com/sun/tools/javap/ClassWriter.java
index 2483e99e49a..764f93bd54a 100644
--- a/src/jdk.jdeps/share/classes/com/sun/tools/javap/ClassWriter.java
+++ b/src/jdk.jdeps/share/classes/com/sun/tools/javap/ClassWriter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,10 +25,12 @@
 
 package com.sun.tools.javap;
 
+import java.lang.reflect.AccessFlag;
 import java.net.URI;
 import java.text.DateFormat;
 import java.util.Collection;
 import java.util.Date;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Set;
 
@@ -149,7 +151,7 @@ public boolean write(ClassModel cm) {
             indent(-1);
         }
 
-        writeModifiers(getClassModifiers(cm.flags().flagsMask()));
+        writeModifiers(getClassModifiers(cm.flags()));
 
         if ((classModel.flags().flagsMask() & ACC_MODULE) != 0) {
             var attr = classModel.findAttribute(Attributes.module());
@@ -210,7 +212,7 @@ public boolean write(ClassModel cm) {
             println("minor version: " + classModel.minorVersion());
             println("major version: " + classModel.majorVersion());
             writeList(String.format("flags: (0x%04x) ", cm.flags().flagsMask()),
-                    getClassFlags(cm.flags().flagsMask()), "\n");
+                    getClassFlags(cm.flags()), "\n");
             print("this_class: #");print(() -> classModel.thisClass().index());
             tab();
             print(() -> "// " + classModel.thisClass().asInternalName());
@@ -416,7 +418,7 @@ protected void writeField(FieldModel f) {
         if (!options.checkAccess(f.flags().flagsMask()))
             return;
 
-        var flags = AccessFlags.ofField(f.flags().flagsMask());
+        var flags = f.flags();
         writeModifiers(flagsReportUnknown(flags).stream().filter(fl -> fl.sourceModifier())
                 .map(fl -> Modifier.toString(fl.mask())).toList());
         print(() -> sigPrinter.print(
@@ -794,9 +796,16 @@ else switch (c) {
         }
     }
 
-    private Set<String> getClassModifiers(int mask) {
-        return getModifiers(flagsReportUnknown(AccessFlags.ofClass((mask & ACC_INTERFACE) != 0
-                ? mask & ~ACC_ABSTRACT : mask)));
+    private Set<String> getClassModifiers(AccessFlags flags) {
+        var flagSet = flagsReportUnknown(flags);
+        Set<AccessFlag> set;
+        if (flagSet.contains(AccessFlag.INTERFACE)) {
+            set = EnumSet.copyOf(flagSet);
+            set.remove(AccessFlag.ABSTRACT);
+        } else {
+            set = flagSet;
+        }
+        return getModifiers(set);
     }
 
     private static Set<String> getModifiers(Set<java.lang.reflect.AccessFlag> flags) {
@@ -806,16 +815,8 @@ private static Set<String> getModifiers(Set<java.lang.reflect.AccessFlag> flags)
         return s;
     }
 
-    private Set<String> getClassFlags(int mask) {
-        return getFlags(mask, flagsReportUnknown(AccessFlags.ofClass(mask)));
-    }
-
-    private Set<String> getMethodFlags(int mask) {
-        return getFlags(mask, flagsReportUnknown(AccessFlags.ofMethod(mask)));
-    }
-
-    private Set<String> getFieldFlags(int mask) {
-        return getFlags(mask, flagsReportUnknown(AccessFlags.ofField(mask)));
+    private Set<String> getClassFlags(AccessFlags flags) {
+        return getFlags(flags.flagsMask(), flagsReportUnknown(flags));
     }
 
     private static Set<String> getFlags(int mask, Set<java.lang.reflect.AccessFlag> flags) {
diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c b/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c
index f91f16104ca..cf2de806119 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -93,8 +93,8 @@ static jrawMonitorID callbackBlock;
  *   not blocking might mean that a return would continue execution of
  *   some java thread in the middle of VM_DEATH, this seems troubled.
  *
- *   WARNING: No not 'return' or 'goto' out of the BEGIN_CALLBACK/END_CALLBACK
- *            block, this will mess up the count.
+ *   WARNING: Do not 'return' or 'goto' out of the BEGIN_CALLBACK/END_CALLBACK
+ *            block. This will mess up the active_callbacks count.
  */
 
 #define BEGIN_CALLBACK()                                                \
@@ -1709,6 +1709,18 @@ eventHandler_unlock(void)
     debugMonitorExit(handlerLock);
 }
 
+void
+callback_lock(void)
+{
+    debugMonitorEnter(callbackLock);
+}
+
+void
+callback_unlock(void)
+{
+    debugMonitorExit(callbackLock);
+}
+
 /***** handler creation *****/
 
 HandlerNode *
diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.h b/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.h
index c4a7aa0c441..096b1ed795a 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.h
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -78,6 +78,9 @@ void eventHandler_waitForActiveCallbacks();
 void eventHandler_lock(void);
 void eventHandler_unlock(void);
 
+void callback_lock(void);
+void callback_unlock(void);
+
 jboolean eventHandler_synthesizeUnloadEvent(char *signature, JNIEnv *env);
 
 jclass getMethodClass(jvmtiEnv *jvmti_env, jmethodID method);
diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c b/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
index e1b4d2f3ab6..4b32430ad7b 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -719,7 +719,9 @@ invoker_completeInvokeRequest(jthread thread)
     exc = NULL;
     id  = 0;
 
-    eventHandler_lock(); /* for proper lock order */
+    callback_lock();     /* for proper lock order in threadControl getLocks() */
+    eventHandler_lock(); /* for proper lock order in threadControl getLocks() */
+    stepControl_lock();  /* for proper lock order in threadControl getLocks() */
     debugMonitorEnter(invokerLock);
 
     request = threadControl_getInvokeRequest(thread);
@@ -772,7 +774,7 @@ invoker_completeInvokeRequest(jthread thread)
      * We cannot delete saved exception or return value references
      * since otherwise a deleted handle would escape when writing
      * the response to the stream. Instead, we clean those refs up
-     * after writing the respone.
+     * after writing the response.
      */
     deleteGlobalArgumentRefs(env, request);
 
@@ -790,7 +792,9 @@ invoker_completeInvokeRequest(jthread thread)
      * Give up the lock before I/O operation
      */
     debugMonitorExit(invokerLock);
+    stepControl_unlock();
     eventHandler_unlock();
+    callback_unlock();
 
     if (!detached) {
         outStream_initReply(&out, id);
diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/stepControl.c b/src/jdk.jdwp.agent/share/native/libjdwp/stepControl.c
index 0611e8fc213..aeec8175b17 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/stepControl.c
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/stepControl.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -805,7 +805,8 @@ stepControl_beginStep(JNIEnv *env, jthread thread, jint size, jint depth,
     LOG_STEP(("stepControl_beginStep: thread=%p,size=%d,depth=%d",
               thread, size, depth));
 
-    eventHandler_lock(); /* for proper lock order */
+    callback_lock();     /* for proper lock order in threadControl getLocks() */
+    eventHandler_lock(); /* for proper lock order in threadControl getLocks() */
     stepControl_lock();
 
     step = threadControl_getStepRequest(thread);
@@ -852,6 +853,7 @@ stepControl_beginStep(JNIEnv *env, jthread thread, jint size, jint depth,
 
     stepControl_unlock();
     eventHandler_unlock();
+    callback_unlock();
 
     return error;
 }
diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c b/src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c
index 00c34844c98..220e0040979 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c
@@ -642,26 +642,31 @@ getLocks(void)
      * thread) needs to be grabbed here. This allows thread control
      * code to safely suspend and resume the application threads
      * while ensuring they don't hold a critical lock.
+     *
+     * stepControl_beginStep() grabs the eventHandler lock and stepControl lock
+     * before eventually ending up here, so we need to maintain that order here.
+     * Similarly, invoker_completeInvokeRequest() grabs the eventHandler lock
+     * and invoker lock.
      */
-
+    callback_lock();
     eventHandler_lock();
+    stepControl_lock();
     invoker_lock();
     eventHelper_lock();
-    stepControl_lock();
-    commonRef_lock();
     debugMonitorEnter(threadLock);
-
+    commonRef_lock();
 }
 
 static void
 releaseLocks(void)
 {
-    debugMonitorExit(threadLock);
     commonRef_unlock();
-    stepControl_unlock();
+    debugMonitorExit(threadLock);
     eventHelper_unlock();
     invoker_unlock();
+    stepControl_unlock();
     eventHandler_unlock();
+    callback_unlock();
 }
 
 void
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/EventControl.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/EventControl.java
index 71569c30273..f086bbf8847 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/EventControl.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/EventControl.java
@@ -299,7 +299,7 @@ private static Control defineEnabled(PlatformEventType type) {
     }
 
     private static Control defineThreshold(PlatformEventType type) {
-        String def = type.getAnnotationValue(Threshold.class, "0 ns");
+        String def = type.getAnnotationValue(Threshold.class, ThresholdSetting.DEFAULT_VALUE);
         type.add(PrivateAccess.getInstance().newSettingDescriptor(TYPE_THRESHOLD, Threshold.NAME, def, Collections.emptyList()));
         return new Control(new ThresholdSetting(type), def);
     }
@@ -311,13 +311,13 @@ private static Control defineStackTrace(PlatformEventType type) {
     }
 
     private static Control defineCutoff(PlatformEventType type) {
-        String def = type.getAnnotationValue(Cutoff.class, Cutoff.INFINITY);
+        String def = type.getAnnotationValue(Cutoff.class, CutoffSetting.DEFAULT_VALUE);
         type.add(PrivateAccess.getInstance().newSettingDescriptor(TYPE_CUTOFF, Cutoff.NAME, def, Collections.emptyList()));
         return new Control(new CutoffSetting(type), def);
     }
 
     private static Control defineThrottle(PlatformEventType type) {
-        String def = type.getAnnotationValue(Throttle.class, Throttle.DEFAULT);
+        String def = type.getAnnotationValue(Throttle.class, ThrottleSetting.DEFAULT_VALUE);
         type.add(PrivateAccess.getInstance().newSettingDescriptor(TYPE_THROTTLE, Throttle.NAME, def, Collections.emptyList()));
         return new Control(new ThrottleSetting(type), def);
     }
@@ -330,7 +330,7 @@ private static Control defineLevel(PlatformEventType type) {
     }
 
     private static Control definePeriod(PlatformEventType type) {
-        String def = type.getAnnotationValue(Period.class, "everyChunk");
+        String def = type.getAnnotationValue(Period.class, PeriodSetting.DEFAULT_VALUE);
         type.add(PrivateAccess.getInstance().newSettingDescriptor(TYPE_PERIOD, PeriodSetting.NAME, def, Collections.emptyList()));
         return new Control(new PeriodSetting(type), def);
     }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanSetting.java
new file mode 100644
index 00000000000..72ffcac72c9
--- /dev/null
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanSetting.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jfr.internal.settings;
+
+import java.util.Objects;
+import java.util.Set;
+
+import jdk.jfr.internal.PlatformEventType;
+
+abstract class BooleanSetting extends JDKSettingControl {
+    private final PlatformEventType eventType;
+    private final String defaultValue;
+    private String value;
+
+    public BooleanSetting(PlatformEventType eventType, String defaultValue) {
+        this.eventType = Objects.requireNonNull(eventType);
+        this.defaultValue = defaultValue;
+        this.value = defaultValue;
+        if (parse(defaultValue) == null) {
+            throw new InternalError("Only 'true' or 'false' is allowed with class BooleanSetting");
+        }
+    }
+
+    protected abstract void apply(PlatformEventType eventType, boolean value);
+
+    @Override
+    public String combine(Set<String> values) {
+        if (values.contains("true")) {
+            return "true";
+        }
+        if (values.contains("false")) {
+            return "false";
+        }
+        return defaultValue;
+    }
+
+    @Override
+    public void setValue(String value) {
+        Boolean b = parse(value);
+        if (b != null) {
+            apply(eventType, b.booleanValue());
+            this.value = value;
+        }
+    }
+
+    @Override
+    public String getValue() {
+        return value;
+    }
+
+    private static Boolean parse(String value) {
+        if ("true".equals(value)) {
+            return Boolean.TRUE;
+        }
+        if ("false".equals(value)) {
+            return Boolean.FALSE;
+        }
+        return null;
+    }
+}
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/CutoffSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/CutoffSetting.java
index 553336b59e2..68950d71b63 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/CutoffSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/CutoffSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,8 @@
 
 package jdk.jfr.internal.settings;
 
+import static jdk.jfr.internal.util.ValueParser.MISSING;
+
 import java.util.Objects;
 import java.util.Set;
 
@@ -43,8 +45,8 @@
 @Name(Type.SETTINGS_PREFIX + "Cutoff")
 @Timespan
 public final class CutoffSetting extends JDKSettingControl {
-
-    private String value = "0 ns";
+    public static final String DEFAULT_VALUE = ValueParser.INFINITY;
+    private String value = DEFAULT_VALUE;
     private final PlatformEventType eventType;
 
     public CutoffSetting(PlatformEventType eventType) {
@@ -54,22 +56,24 @@ public CutoffSetting(PlatformEventType eventType) {
     @Override
     public String combine(Set<String> values) {
         long max = 0;
-        String text = "0 ns";
+        String text = null;
         for (String value : values) {
-            long l =  ValueParser.parseTimespanWithInfinity(value);
-            if (l > max) {
+            long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+            if (nanos != MISSING && nanos > max) {
                 text = value;
-                max = l;
+                max = nanos;
             }
         }
-        return text;
+        return Objects.requireNonNullElse(text, DEFAULT_VALUE);
     }
 
     @Override
     public void setValue(String value) {
-        long l =  ValueParser.parseTimespanWithInfinity(value);
-        this.value = value;
-        eventType.setCutoff(l);
+        long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+        if (nanos != MISSING) {
+            eventType.setCutoff(nanos);
+            this.value = value;
+        }
     }
 
     @Override
@@ -81,10 +85,6 @@ public static long parseValueSafe(String value) {
         if (value == null) {
             return 0L;
         }
-        try {
-            return ValueParser.parseTimespanWithInfinity(value);
-        } catch (NumberFormatException nfe) {
-            return 0L;
-        }
+        return ValueParser.parseTimespanWithInfinity(value, 0L);
     }
 }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/EnabledSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/EnabledSetting.java
index 77a57a9b75b..e81bce484f3 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/EnabledSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/EnabledSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,9 +25,6 @@
 
 package jdk.jfr.internal.settings;
 
-import java.util.Objects;
-import java.util.Set;
-
 import jdk.jfr.Description;
 import jdk.jfr.BooleanFlag;
 import jdk.jfr.Label;
@@ -41,33 +38,18 @@
 @Description("Record event")
 @Name(Type.SETTINGS_PREFIX + "Enabled")
 @BooleanFlag
-public final class EnabledSetting extends JDKSettingControl {
-    private final BooleanValue booleanValue;
-    private final PlatformEventType eventType;
-
+public final class EnabledSetting extends BooleanSetting {
     public EnabledSetting(PlatformEventType eventType, String defaultValue) {
-        this.booleanValue = BooleanValue.valueOf(defaultValue);
-        this.eventType = Objects.requireNonNull(eventType);
-    }
-
-    @Override
-    public String combine(Set<String> values) {
-        return booleanValue.union(values);
+        super(eventType, defaultValue);
     }
 
     @Override
-    public void setValue(String value) {
-        booleanValue.setValue(value);
-        eventType.setEnabled(booleanValue.getBoolean());
+    protected void apply(PlatformEventType eventType, boolean value) {
+        eventType.setEnabled(value);
         if (eventType.isEnabled() && !eventType.isJVM()) {
             if (!eventType.isInstrumented()) {
                 eventType.markForInstrumentation(true);
             }
         }
     }
-
-    @Override
-    public String getValue() {
-        return booleanValue.getValue();
-    }
 }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/LevelSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/LevelSetting.java
index b6aa7500d4b..9531f75c925 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/LevelSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/LevelSetting.java
@@ -47,30 +47,29 @@ public final class LevelSetting extends JDKSettingControl {
     public LevelSetting(PlatformEventType eventType, String[] levels) {
         this.eventType = Objects.requireNonNull(eventType);
         this.levels = Arrays.asList(Objects.requireNonNull(levels));
+        this.value = levels[0];
     }
 
     @Override
     public String combine(Set<String> values) {
-        int maxIndex = 0;
+        int maxIndex = 0; // index 0 contains the default value
         for (String value : values) {
-            maxIndex = Math.max(maxIndex, indexOf(value));
+            maxIndex = Math.max(maxIndex, levels.indexOf(value));
         }
         return levels.get(maxIndex);
     }
 
     @Override
     public void setValue(String value) {
-        this.value = value;
-        this.eventType.setLevel(indexOf(value));
+        int index = levels.indexOf(value);
+        if (index != -1) {
+            this.eventType.setLevel(index);
+            this.value = value;
+        }
     }
 
     @Override
     public String getValue() {
         return value;
     }
-
-    private int indexOf(String value) {
-        int index = levels.indexOf(value);
-        return index < 0 ? 0 : index;
-    }
 }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/PeriodSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/PeriodSetting.java
index 05b5a08a3bb..22fef2691aa 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/PeriodSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/PeriodSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,6 +35,7 @@
 import jdk.jfr.internal.PlatformEventType;
 import jdk.jfr.internal.Type;
 import jdk.jfr.internal.util.ValueParser;
+import static jdk.jfr.internal.util.ValueParser.MISSING;
 
 @MetadataDefinition
 @Label("Period")
@@ -46,6 +47,7 @@ public final class PeriodSetting extends JDKSettingControl {
     public static final String EVERY_CHUNK = "everyChunk";
     public static final String BEGIN_CHUNK = "beginChunk";
     public static final String END_CHUNK = "endChunk";
+    public static final String DEFAULT_VALUE = EVERY_CHUNK;
     public static final String NAME = "period";
     private final PlatformEventType eventType;
     private String value = EVERY_CHUNK;
@@ -56,7 +58,6 @@ public PeriodSetting(PlatformEventType eventType) {
 
     @Override
     public String combine(Set<String> values) {
-
         boolean beginChunk = false;
         boolean endChunk = false;
         Long min = null;
@@ -74,15 +75,11 @@ public String combine(Set<String> values) {
                 endChunk = true;
                 break;
             default:
-                long l = ValueParser.parseTimespanWithInfinity(value);
-                // Always accept first specified value
-                if (min == null) {
-                    text = value;
-                    min = l;
-                } else {
-                    if (l < min) {
+                long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+                if (nanos != MISSING) {
+                    if (min == null || nanos < min) {
                         text = value;
-                        min = l;
+                        min = nanos;
                     }
                 }
             }
@@ -97,7 +94,7 @@ public String combine(Set<String> values) {
         if (!beginChunk && endChunk) {
             return END_CHUNK;
         }
-        return EVERY_CHUNK; // also default
+        return DEFAULT_VALUE; // "everyChunk" is default
     }
 
     @Override
@@ -113,7 +110,10 @@ public void setValue(String value) {
             eventType.setPeriod(0, false, true);
             break;
         default:
-            long nanos = ValueParser.parseTimespanWithInfinity(value);
+            long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+            if (nanos == MISSING) {
+                return;
+            }
             if (nanos == 0 || nanos == Long.MAX_VALUE) {
                 eventType.setPeriod(nanos, false, false);
             } else {
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/StackTraceSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/StackTraceSetting.java
index cfd85a0f240..45489ebc691 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/StackTraceSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/StackTraceSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,11 +25,8 @@
 
 package jdk.jfr.internal.settings;
 
-import java.util.Objects;
-import java.util.Set;
-
-import jdk.jfr.Description;
 import jdk.jfr.BooleanFlag;
+import jdk.jfr.Description;
 import jdk.jfr.Label;
 import jdk.jfr.MetadataDefinition;
 import jdk.jfr.Name;
@@ -41,30 +38,16 @@
 @Name(Type.SETTINGS_PREFIX + "StackTrace")
 @Description("Record stack traces")
 @BooleanFlag
-public final class StackTraceSetting extends JDKSettingControl {
-    private static final long typeId =  Type.getTypeId(StackTraceSetting.class);
-    private final BooleanValue booleanValue;
-    private final PlatformEventType eventType;
+public final class StackTraceSetting extends BooleanSetting {
+    private static final long typeId = Type.getTypeId(StackTraceSetting.class);
 
     public StackTraceSetting(PlatformEventType eventType, String defaultValue) {
-        this.booleanValue = BooleanValue.valueOf(defaultValue);
-        this.eventType = Objects.requireNonNull(eventType);
-    }
-
-    @Override
-    public String combine(Set<String> values) {
-        return booleanValue.union(values);
-    }
-
-    @Override
-    public void setValue(String value) {
-        booleanValue.setValue(value);
-        eventType.setStackTraceEnabled(booleanValue.getBoolean());
+        super(eventType, defaultValue);
     }
 
     @Override
-    public String getValue() {
-        return booleanValue.getValue();
+    protected void apply(PlatformEventType eventType, boolean value) {
+        eventType.setStackTraceEnabled(value);
     }
 
     public static boolean isType(long typeId) {
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThresholdSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThresholdSetting.java
index 1a7138b11cd..8870417f9dd 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThresholdSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThresholdSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,8 @@
 
 package jdk.jfr.internal.settings;
 
+import static jdk.jfr.internal.util.ValueParser.MISSING;
+
 import java.util.Objects;
 import java.util.Set;
 
@@ -36,14 +38,16 @@
 import jdk.jfr.internal.PlatformEventType;
 import jdk.jfr.internal.Type;
 import jdk.jfr.internal.util.ValueParser;
+
 @MetadataDefinition
 @Label("Threshold")
 @Name(Type.SETTINGS_PREFIX + "Threshold")
 @Description("Record event with duration above or equal to threshold")
 @Timespan
 public final class ThresholdSetting extends JDKSettingControl {
+    public static final String DEFAULT_VALUE = "0 ns";
     private static final long typeId = Type.getTypeId(ThresholdSetting.class);
-    private String value = "0 ns";
+    private String value = DEFAULT_VALUE;
     private final PlatformEventType eventType;
 
     public ThresholdSetting(PlatformEventType eventType) {
@@ -55,26 +59,24 @@ public String combine(Set<String> values) {
         Long min = null;
         String text = null;
         for (String value : values) {
-            long l = ValueParser.parseTimespanWithInfinity(value);
-            // always accept first value
-            if (min == null) {
-                min = l;
-                text = value;
-            } else {
-                if (l < min) {
+            long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+            if (nanos != MISSING) {
+                if (min == null || nanos < min) {
                     text = value;
-                    min = l;
+                    min = nanos;
                 }
             }
         }
-        return text == null ? "0 ns" : text;
+        return Objects.requireNonNullElse(text, DEFAULT_VALUE);
     }
 
     @Override
     public void setValue(String value) {
-        long l = ValueParser.parseTimespanWithInfinity(value);
-        this.value = value;
-        eventType.setThreshold(l);
+        long nanos = ValueParser.parseTimespanWithInfinity(value, MISSING);
+        if (nanos != MISSING) {
+            eventType.setThreshold(nanos);
+            this.value = value;
+        }
     }
 
     @Override
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleSetting.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleSetting.java
index 45750296389..55757050b80 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleSetting.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleSetting.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, Datadog, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -26,6 +26,9 @@
 
 package jdk.jfr.internal.settings;
 
+import static jdk.jfr.internal.util.TimespanUnit.SECONDS;
+import static jdk.jfr.internal.util.TimespanUnit.MILLISECONDS;
+
 import java.util.Objects;
 import java.util.Set;
 
@@ -34,17 +37,20 @@
 import jdk.jfr.MetadataDefinition;
 import jdk.jfr.Name;
 import jdk.jfr.internal.PlatformEventType;
+import jdk.jfr.internal.Throttle;
 import jdk.jfr.internal.Type;
+import jdk.jfr.internal.util.Rate;
+import jdk.jfr.internal.util.TimespanUnit;
+import jdk.jfr.internal.util.Utils;
 
 @MetadataDefinition
 @Label("Event Emission Throttle")
 @Description("Throttles the emission rate for an event")
 @Name(Type.SETTINGS_PREFIX + "Throttle")
 public final class ThrottleSetting extends JDKSettingControl {
-    static final String OFF_TEXT = "off";
-    private static final long OFF = -2;
-    private String value = "0/s";
+    public static final String DEFAULT_VALUE = Throttle.DEFAULT;
     private final PlatformEventType eventType;
+    private String value = DEFAULT_VALUE;
 
     public ThrottleSetting(PlatformEventType eventType) {
        this.eventType = Objects.requireNonNull(eventType);
@@ -52,75 +58,51 @@ public ThrottleSetting(PlatformEventType eventType) {
 
     @Override
     public String combine(Set<String> values) {
-        long max = OFF;
-        String text = "off";
+        Rate max = null;
+        String text = null;
         for (String value : values) {
-            long l = parseValueSafe(value);
-            if (l > max) {
-                text = value;
-                max = l;
+            Rate rate = Rate.of(value);
+            if (rate != null) {
+                if (max == null || rate.isHigher(max)) {
+                    text = value;
+                    max = rate;
+                }
             }
         }
-        return text;
+        // "off" is default
+        return Objects.requireNonNullElse(text, DEFAULT_VALUE);
     }
 
-    private static long parseValueSafe(String s) {
-        long value = 0L;
-        try {
-            value = parseThrottleValue(s);
-        } catch (NumberFormatException nfe) {
+    @Override
+    public void setValue(String value) {
+        if ("off".equals(value)) {
+            eventType.setThrottle(-2, 1000);
+            this.value = value;
+            return;
         }
-        return value;
-    }
 
-    @Override
-    public void setValue(String s) {
-        long size = 0;
-        long millis = 1000;
-        try {
-            size = parseThrottleValue(s);
-            millis = parseThrottleTimeUnit(s);
-            this.value = s;
-        } catch (NumberFormatException nfe) {
+        Rate rate = Rate.of(value);
+        if (rate != null) {
+            long millis = 1000;
+            long samples = rate.amount();
+            TimespanUnit unit = rate.unit();
+            // if unit is more than 1 s, set millis
+            if (unit.nanos > SECONDS.nanos) {
+                millis = unit.nanos / MILLISECONDS.nanos;
+            }
+            // if unit is less than 1 s, scale samples
+            if (unit.nanos < SECONDS.nanos) {
+                long perSecond = SECONDS.nanos / unit.nanos;
+                samples *= Utils.multiplyOverflow(samples, perSecond, Long.MAX_VALUE);
+            }
+            eventType.setThrottle(samples, millis);
+            this.value = value;
         }
-        eventType.setThrottle(size, millis);
     }
 
     @Override
     public String getValue() {
         return value;
     }
-
-    private static long parseThrottleValue(String s) {
-        if (s.equals(OFF_TEXT)) {
-            return OFF;
-        }
-        String parsedValue = parseThrottleString(s, true);
-        long normalizedValue = 0;
-        try {
-            normalizedValue = ThrottleUnit.normalizeValueAsMillis(Long.parseLong(parsedValue), s);
-        } catch (NumberFormatException nfe) {
-            throwThrottleNumberFormatException(s);
-        }
-        return normalizedValue;
-    }
-
-    private static long parseThrottleTimeUnit(String s) {
-        return ThrottleUnit.asMillis(s);
-    }
-
-    // Expected input format is "x/y" where x is a non-negative long
-    // and y is a time unit. Split the string at the delimiter.
-    static String parseThrottleString(String s, boolean value) {
-        String[] split = s.split("/");
-        if (split.length != 2) {
-            throwThrottleNumberFormatException(s);
-        }
-        return value ? split[0].trim() : split[1].trim();
-    }
-
-    private static void throwThrottleNumberFormatException(String s) {
-        throw new NumberFormatException("'" + s + "' is not valid. Should be a non-negative numeric value followed by a delimiter. i.e. '/', and then followed by a unit e.g. 100/s.");
-    }
 }
 
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleUnit.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleUnit.java
deleted file mode 100644
index ec2fafc7656..00000000000
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/ThrottleUnit.java
+++ /dev/null
@@ -1,82 +0,0 @@
-/*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2020, Datadog, Inc. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-package jdk.jfr.internal.settings;
-
-import java.util.concurrent.TimeUnit;
-
-enum ThrottleUnit {
-        NANOSECONDS("ns", TimeUnit.SECONDS.toNanos(1), TimeUnit.SECONDS.toMillis(1)),
-        MICROSECONDS("us", TimeUnit.SECONDS.toNanos(1) / 1000, TimeUnit.SECONDS.toMillis(1)),
-        MILLISECONDS("ms", TimeUnit.SECONDS.toMillis(1), TimeUnit.SECONDS.toMillis(1)),
-        SECONDS("s", 1, TimeUnit.SECONDS.toMillis(1)),
-        MINUTES("m", 1, TimeUnit.MINUTES.toMillis(1)),
-        HOUR("h", 1, TimeUnit.HOURS.toMillis(1)),
-        DAY("d", 1, TimeUnit.DAYS.toMillis(1));
-
-        private final String text;
-        private final long factor;
-        private final long millis;
-
-        ThrottleUnit(String t, long factor, long millis) {
-            this.text = t;
-            this.factor = factor;
-            this.millis = millis;
-        }
-
-        private static ThrottleUnit parse(String s) {
-            if (s.equals(ThrottleSetting.OFF_TEXT)) {
-                return MILLISECONDS;
-            }
-            return unit(ThrottleSetting.parseThrottleString(s, false));
-        }
-
-        private static ThrottleUnit unit(String s) {
-            if (s.endsWith("ns") || s.endsWith("us") || s.endsWith("ms")) {
-                return value(s.substring(s.length() - 2));
-            }
-            if (s.endsWith("s") || s.endsWith("m") || s.endsWith("h") || s.endsWith("d")) {
-                return value(s.substring(s.length() - 1));
-            }
-            throw new NumberFormatException("'" + s + "' is not a valid time unit.");
-        }
-
-        private static ThrottleUnit value(String s) {
-            for (ThrottleUnit t : values()) {
-                if (t.text.equals(s)) {
-                    return t;
-                }
-            }
-            throw new NumberFormatException("'" + s + "' is not a valid time unit.");
-        }
-
-        static long asMillis(String s) {
-            return parse(s).millis;
-        }
-
-        static long normalizeValueAsMillis(long value, String s) {
-            return value * parse(s).factor;
-        }
-    }
\ No newline at end of file
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanValue.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Rate.java
similarity index 50%
rename from src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanValue.java
rename to src/jdk.jfr/share/classes/jdk/jfr/internal/util/Rate.java
index d8f46d76787..f32436a5e0f 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/settings/BooleanValue.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Rate.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,53 +22,37 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
+package jdk.jfr.internal.util;
 
-package jdk.jfr.internal.settings;
+public record Rate(long amount, TimespanUnit unit) {
 
-import java.util.Set;
-
-/**
- * Helper class for settings that use boolean numbers
- *
- */
-final class BooleanValue  {
-    private String value = "false";
-    private boolean booleanValue;
-
-    private BooleanValue(boolean b) {
-        booleanValue = b;
-        value = b ? "true" : "false";
-    }
-
-    public String union(Set<String> values) {
-        for (String v : values) {
-            if ("true".equals(v)) {
-                return "true";
+    public static Rate of(String text) {
+        String[] splitted = text.split("/");
+        if (splitted.length != 2) {
+            return null;
+        }
+        String value = splitted[0].strip();
+        String unit = splitted[1].strip();
+        TimespanUnit tu = TimespanUnit.fromText(unit);
+        if (unit == null) {
+            return null;
+        }
+        try {
+            long v = Long.parseLong(value);
+            if (v >= 0) {
+                return new Rate(v, tu);
             }
+        } catch (NumberFormatException nfe) {
+            // Ignore
         }
-        return "false";
-    }
-
-    public void setValue(String value) {
-        this.value = value;
-        this.booleanValue = Boolean.valueOf(value);
+        return null;
     }
 
-    public final String getValue() {
-        return this.value;
+    public boolean isHigher(Rate that) {
+        return this.inNanos() > that.inNanos();
     }
 
-    public boolean getBoolean() {
-        return booleanValue;
-    }
-
-    public static BooleanValue valueOf(String defaultValue) {
-        if ("true".equals(defaultValue)) {
-            return new BooleanValue(true);
-        }
-        if ("false".equals(defaultValue)) {
-            return new BooleanValue(false);
-        }
-        throw new InternalError("Unknown default value for settings '" + defaultValue + "'");
+    private double inNanos() {
+        return (double) amount / unit.nanos;
     }
 }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/TimespanUnit.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/TimespanUnit.java
new file mode 100644
index 00000000000..9026f59b68b
--- /dev/null
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/TimespanUnit.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.jfr.internal.util;
+
+public enum TimespanUnit {
+    NANOSECONDS ("ns",                           1L, 1000),
+    MICROSECONDS("us",                        1000L, 1000),
+    MILLISECONDS("ms",                   1_000_000L, 1000),
+    SECONDS     ("s",                1_000_000_000L,   60),
+    MINUTES     ("m",           60 * 1_000_000_000L,   60),
+    HOURS       ("h",      60 * 60 * 1_000_000_000L,   24),
+    DAYS        ("d", 24 * 60 * 60 * 1_000_000_000L,    7);
+    public final String text;
+    public final long nanos;
+    public final int size;
+    TimespanUnit(String text, long nanos, int size) {
+        this.text = text;
+        this.nanos = nanos;
+        this.size = size;
+    }
+
+    public static TimespanUnit fromText(String text) {
+        for (TimespanUnit tu : values()) {
+            // Case-sensitive by design
+            if (tu.text.equals(text)) {
+                return tu;
+            }
+        }
+        return null;
+    }
+}
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Utils.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Utils.java
index ae83727096a..b5ae906c71c 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Utils.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/Utils.java
@@ -430,4 +430,12 @@ public static boolean isJDKClass(Class<?> type) {
         // but only if it is safe and there is a mechanism to register event
         // classes in other modules besides jdk.jfr and java.base.
     }
+
+    public static long multiplyOverflow(long a, long b, long defaultValue) {
+        try {
+            return Math.multiplyExact(a, b);
+        } catch (ArithmeticException ae) {
+            return defaultValue;
+        }
+    }
 }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueFormatter.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueFormatter.java
index 8fd47dbf5b3..53a11101944 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueFormatter.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueFormatter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,23 +40,6 @@
 import jdk.jfr.consumer.RecordedMethod;
 
 public final class ValueFormatter {
-    private static enum TimespanUnit {
-        NANOSECONDS("ns", 1000),
-        MICROSECONDS("us", 1000),
-        MILLISECONDS("ms", 1000),
-        SECONDS("s", 60), MINUTES("m", 60),
-        HOURS("h", 24),
-        DAYS("d", 7);
-
-        private final String text;
-        private final long amount;
-
-        TimespanUnit(String unit, long amount) {
-            this.text = unit;
-            this.amount = amount;
-        }
-    }
-
     private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ofPattern("HH:mm:ss");
     private static final Duration MICRO_SECOND = Duration.ofNanos(1_000);
     private static final Duration SECOND = Duration.ofSeconds(1);
@@ -82,7 +65,7 @@ public static String formatTimespan(Duration dValue, String separation) {
         TimespanUnit result = TimespanUnit.NANOSECONDS;
         for (TimespanUnit unit : TimespanUnit.values()) {
             result = unit;
-            long amount = unit.amount;
+            long amount = unit.size;
             if (result == TimespanUnit.DAYS || value < amount || value % amount != 0) {
                 break;
             }
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueParser.java b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueParser.java
index 730c83daaae..e4482c92368 100644
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueParser.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/util/ValueParser.java
@@ -32,7 +32,16 @@
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 public final class ValueParser {
-    private static final String INFINITY = "infinity";
+    public static final String INFINITY = "infinity";
+    public static final long MISSING = Long.MIN_VALUE;
+
+    public static long parseTimespanWithInfinity(String s, long defaultValue) {
+        try {
+            return parseTimespanWithInfinity(s);
+        } catch (NumberFormatException nfe) {
+            return defaultValue;
+        }
+    }
 
     public static long parseTimespanWithInfinity(String s) {
         if (INFINITY.equals(s)) {
diff --git a/src/jdk.jshell/share/classes/jdk/jshell/TreeDissector.java b/src/jdk.jshell/share/classes/jdk/jshell/TreeDissector.java
index 518a61d6969..fc259b8bc7c 100644
--- a/src/jdk.jshell/share/classes/jdk/jshell/TreeDissector.java
+++ b/src/jdk.jshell/share/classes/jdk/jshell/TreeDissector.java
@@ -246,7 +246,7 @@ private static class TDSignatureGenerator extends Types.SignatureGenerator {
         StringBuilder sb = new StringBuilder();
 
         TDSignatureGenerator(Types types) {
-            super(types);
+            types.super();
         }
 
         @Override
diff --git a/test/hotspot/gtest/utilities/test_utf8.cpp b/test/hotspot/gtest/utilities/test_utf8.cpp
index ffd8121075b..80f6671207b 100644
--- a/test/hotspot/gtest/utilities/test_utf8.cpp
+++ b/test/hotspot/gtest/utilities/test_utf8.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,6 +22,8 @@
  */
 
 #include "precompiled.hpp"
+#include "nmt/memflags.hpp"
+#include "runtime/os.hpp"
 #include "utilities/utf8.hpp"
 #include "unittest.hpp"
 
@@ -101,5 +103,105 @@ TEST_VM(utf8, jbyte_length) {
     UNICODE::as_utf8(str, 19, res, i);
     EXPECT_TRUE(test_stamp(res + i, sizeof(res) - i));
   }
+}
+
+TEST_VM(utf8, truncation) {
+
+  // Test that truncation removes partial encodings as expected.
+
+  const char orig_bytes[] = { 'A', 'B', 'C', 'D', 'E', '\0' };
+  const int orig_length = sizeof(orig_bytes)/sizeof(char);
+  ASSERT_TRUE(UTF8::is_legal_utf8((const unsigned char*)orig_bytes, orig_length - 1, false));
+  const char* orig_str = &orig_bytes[0];
+  ASSERT_EQ((int)strlen(orig_str), orig_length - 1);
+
+  unsigned char* temp_bytes;
+  const char* temp_str;
+  char* utf8;
+  int n_utf8; // Number of bytes in the encoding
+
+  // Test 1: a valid UTF8 "ascii" ending string should be returned as-is
+
+  temp_bytes = (unsigned char*) os::malloc(sizeof(unsigned char) * orig_length, mtTest);
+  strcpy((char*)temp_bytes, orig_str);
+  temp_str = (const char*) temp_bytes;
+  UTF8::truncate_to_legal_utf8(temp_bytes, orig_length);
+  ASSERT_EQ((int)strlen(temp_str), orig_length - 1) << "bytes should be unchanged";
+  ASSERT_EQ(strcmp(orig_str, temp_str), 0) << "bytes should be unchanged";
+  os::free(temp_bytes);
+
+  // Test 2: a UTF8 sequence that "ends" with a 2-byte encoding
+  //         drops the 2-byte encoding
+
+  jchar two_byte_char[] = { 0x00D1 }; // N with tilde
+  n_utf8 = 2;
+  utf8 = (char*) os::malloc(sizeof(char) * (n_utf8 + 1), mtTest); // plus NUL
+  UNICODE::convert_to_utf8(two_byte_char, 1, utf8);
+  int utf8_len = (int)strlen(utf8);
+  ASSERT_EQ(utf8_len, n_utf8) << "setup error";
+
+  // Now drop zero or one byte from the end and check it truncates as expected
+  for (int drop = 0; drop < n_utf8; drop++) {
+    int temp_len = orig_length + utf8_len - drop;
+    temp_bytes = (unsigned char*) os::malloc(sizeof(unsigned char) * temp_len, mtTest);
+    temp_str = (const char*) temp_bytes;
+    strcpy((char*)temp_bytes, orig_str);
+    strncat((char*)temp_bytes, utf8, utf8_len - drop);
+    ASSERT_EQ((int)strlen(temp_str), temp_len - 1) << "setup error";
+    UTF8::truncate_to_legal_utf8(temp_bytes, temp_len);
+    ASSERT_EQ((int)strlen(temp_str), orig_length - 1) << "bytes should be truncated to original length";
+    ASSERT_EQ(strcmp(orig_str, temp_str), 0) << "bytes should be truncated to original";
+    os::free(temp_bytes);
+  }
+  os::free(utf8);
+
+  // Test 3: a UTF8 sequence that "ends" with a 3-byte encoding
+  //         drops the 3-byte encoding
+  n_utf8 = 3;
+  jchar three_byte_char[] = { 0x0800 };
+  utf8 = (char*) os::malloc(sizeof(char) * (n_utf8 + 1), mtTest); // plus NUL
+  UNICODE::convert_to_utf8(three_byte_char, 1, utf8);
+  utf8_len = (int)strlen(utf8);
+  ASSERT_EQ(utf8_len, n_utf8) << "setup error";
+
+  // Now drop zero, to two bytes from the end and check it truncates as expected
+  for (int drop = 0; drop < n_utf8; drop++) {
+    int temp_len = orig_length + utf8_len - drop;
+    temp_bytes = (unsigned char*) os::malloc(sizeof(unsigned char) * temp_len, mtTest);
+    temp_str = (const char*) temp_bytes;
+    strcpy((char*)temp_bytes, orig_str);
+    strncat((char*)temp_bytes, utf8, utf8_len - drop);
+    ASSERT_EQ((int)strlen(temp_str), temp_len - 1) << "setup error";
+    UTF8::truncate_to_legal_utf8(temp_bytes, temp_len);
+    ASSERT_EQ((int)strlen(temp_str), orig_length - 1) << "bytes should be truncated to original length";
+    ASSERT_EQ(strcmp(orig_str, temp_str), 0) << "bytes should be truncated to original";
+    os::free(temp_bytes);
+  }
+  os::free(utf8);
+
+  // Test 4: a UTF8 sequence that "ends" with a 6-byte encoding
+  //         drops the 6-byte encoding
+  n_utf8 = 6;
+  jchar six_byte_char[] = { 0xD801, 0xDC37 }; // U+10437 as its UTF-16 surrogate pairs
+  utf8 = (char*) os::malloc(sizeof(char) * (n_utf8 + 1), mtTest); // plus NUL
+  UNICODE::convert_to_utf8(six_byte_char, 2, utf8);
+  utf8_len = (int)strlen(utf8);
+  ASSERT_EQ(utf8_len, n_utf8) << "setup error";
+
+  // Now drop zero to five bytes from the end and check it truncates as expected
+  for (int drop = 0; drop < n_utf8; drop++) {
+    int temp_len = orig_length + utf8_len - drop;
+    temp_bytes = (unsigned char*) os::malloc(sizeof(unsigned char) * temp_len, mtTest);
+    temp_str = (const char*) temp_bytes;
+    strcpy((char*)temp_bytes, orig_str);
+    strncat((char*)temp_bytes, utf8, utf8_len - drop);
+    ASSERT_EQ((int)strlen(temp_str), temp_len - 1) << "setup error";
+    UTF8::truncate_to_legal_utf8(temp_bytes, temp_len);
+    ASSERT_EQ((int)strlen(temp_str), orig_length - 1) << "bytes should be truncated to original length";
+    ASSERT_EQ(strcmp(orig_str, temp_str), 0) << "bytes should be truncated to original";
+    os::free(temp_bytes);
+  }
+  os::free(utf8);
+
 
 }
diff --git a/test/hotspot/jtreg/compiler/c2/TestCastX2P.java b/test/hotspot/jtreg/compiler/c2/TestCastX2P.java
new file mode 100644
index 00000000000..6591692f0cc
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/c2/TestCastX2P.java
@@ -0,0 +1,234 @@
+/*
+ * Copyright (c) 2024, Arm Limited. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.c2;
+
+import jdk.internal.misc.Unsafe;
+import jdk.test.lib.Asserts;
+
+/**
+ * @test TestCastX2P
+ * @summary AArch64: remove extra register copy when converting from long to pointer.
+ * @bug 8336245
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ * @run main/othervm -XX:-TieredCompilation compiler.c2.TestCastX2P
+ */
+
+public class TestCastX2P {
+
+    public static final int LEN = 2040;
+
+    static final Unsafe UNSAFE = Unsafe.getUnsafe();
+
+    public static long lseed = 0xbeef;
+    public static int iseed = 0xbeef;
+    public static short sseed = (short) (0xef);
+    public static byte bseed = (byte) (0xe);
+
+    public static long off1 = 16;
+    public static long off2 = 32;
+    public static long off3 = 64;
+
+    public static class TestLong {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 10_000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putLong(address+i, lseed);
+                }
+            }
+
+            UNSAFE.putLong(address + off1 + 1030, lseed);
+            UNSAFE.putLong(address + 1023, lseed);
+            UNSAFE.putLong(address + off2 + 1001, lseed);
+        }
+    }
+
+    public static class TestLongIndirect {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 1000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putLong(address+i, lseed);
+                }
+            }
+
+            UNSAFE.putLong(address + off1, lseed);
+            UNSAFE.putLong(address + off1 + off2, lseed);
+            UNSAFE.putLong(address + off3, lseed);
+        }
+    }
+
+    public static class TestInt {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 10_000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putInt(address+i, iseed);
+                }
+            }
+
+            UNSAFE.putInt(address + off1 + 274, iseed);
+            UNSAFE.putInt(address + 278, iseed);
+            UNSAFE.putInt(address + off2 + 282, iseed);
+        }
+    }
+
+    public static class TestIntIndirect {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 1000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putInt(address+i, iseed);
+                }
+            }
+
+            UNSAFE.putInt(address + off1, iseed);
+            UNSAFE.putInt(address + off1 + off2, iseed);
+            UNSAFE.putInt(address + off3, iseed);
+        }
+    }
+
+    public static class TestShort {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 10_000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putShort(address+i, sseed);
+                }
+            }
+
+            UNSAFE.putShort(address + off1 + 257, sseed);
+            UNSAFE.putShort(address + 277, sseed);
+            UNSAFE.putShort(address + off2 + 283, sseed);
+        }
+    }
+
+    public static class TestShortIndirect {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 1000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putShort(address+i, sseed);
+                }
+            }
+
+            UNSAFE.putShort(address + off1, sseed);
+            UNSAFE.putShort(address + off1 + off2, sseed);
+            UNSAFE.putShort(address + off3, sseed);
+        }
+    }
+
+    public static class TestByte {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 10_000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putByte(address+i, bseed);
+                }
+            }
+
+            UNSAFE.putByte(address + off1 + 257, bseed);
+            UNSAFE.putByte(address + 277, bseed);
+            UNSAFE.putByte(address + off2 + 283, bseed);
+        }
+    }
+
+    public static class TestByteIndirect {
+
+        private static long address = UNSAFE.allocateMemory(LEN);
+
+        static {
+            for (int k = 0; k < 1000; k++) {
+                for (int i = 0; i < LEN/2; i++) {
+                    UNSAFE.putByte(address+i, bseed);
+                }
+            }
+
+            UNSAFE.putByte(address + off1, bseed);
+            UNSAFE.putByte(address + off1 + off2, bseed);
+            UNSAFE.putByte(address + off3, bseed);
+        }
+    }
+
+    static void test() {
+        TestLong t1 = new TestLong();
+        Asserts.assertEquals(UNSAFE.getLong(t1.address + off1 + 1030), lseed, "put long failed!");
+        Asserts.assertEquals(UNSAFE.getLong(t1.address + 1023), lseed, "put long failed!");
+        Asserts.assertEquals(UNSAFE.getLong(t1.address + off2 + 1001), lseed, "put long failed!");
+
+        TestLongIndirect t2 = new TestLongIndirect();
+        Asserts.assertEquals(UNSAFE.getLong(t2.address + off1), lseed, "put long failed!");
+        Asserts.assertEquals(UNSAFE.getLong(t2.address + off1 + off2), lseed, "put long failed!");
+        Asserts.assertEquals(UNSAFE.getLong(t2.address + off3), lseed, "put long failed!");
+
+        TestInt t3 = new TestInt();
+        Asserts.assertEquals(UNSAFE.getInt(t3.address + off1 + 274), iseed, "put int failed!");
+        Asserts.assertEquals(UNSAFE.getInt(t3.address + 278), iseed, "put int failed!");
+        Asserts.assertEquals(UNSAFE.getInt(t3.address + off2 + 282), iseed, "put int failed!");
+
+        TestIntIndirect t4 = new TestIntIndirect();
+        Asserts.assertEquals(UNSAFE.getInt(t4.address + off1), iseed, "put int failed!");
+        Asserts.assertEquals(UNSAFE.getInt(t4.address + off1 + off2), iseed, "put int failed!");
+        Asserts.assertEquals(UNSAFE.getInt(t4.address + off3), iseed, "put int failed!");
+
+        TestShort t5 = new TestShort();
+        Asserts.assertEquals(UNSAFE.getShort(t5.address + off1 + 257), sseed, "put short failed!");
+        Asserts.assertEquals(UNSAFE.getShort(t5.address + 277), sseed, "put short failed!");
+        Asserts.assertEquals(UNSAFE.getShort(t5.address + off2 + 283), sseed, "put short failed!");
+
+        TestShortIndirect t6 = new TestShortIndirect();
+        Asserts.assertEquals(UNSAFE.getShort(t6.address + off1), sseed, "put short failed!");
+        Asserts.assertEquals(UNSAFE.getShort(t6.address + off1 + off2), sseed, "put short failed!");
+        Asserts.assertEquals(UNSAFE.getShort(t6.address + off3), sseed, "put short failed!");
+
+        TestByte t7 = new TestByte();
+        Asserts.assertEquals(UNSAFE.getByte(t7.address + off1 + 257), bseed, "put byte failed!");
+        Asserts.assertEquals(UNSAFE.getByte(t7.address + 277), bseed, "put byte failed!");
+        Asserts.assertEquals(UNSAFE.getByte(t7.address + off2 + 283), bseed, "put byte failed!");
+
+        TestByteIndirect t8 = new TestByteIndirect();
+        Asserts.assertEquals(UNSAFE.getByte(t8.address + off1), bseed, "put byte failed!");
+        Asserts.assertEquals(UNSAFE.getByte(t8.address + off1 + off2), bseed, "put byte failed!");
+        Asserts.assertEquals(UNSAFE.getByte(t8.address + off3), bseed, "put byte failed!");
+    }
+
+    public static void main(String[] strArr) {
+        test();
+    }
+}
diff --git a/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java b/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java
index 10bc237f2be..23b9321fc35 100644
--- a/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java
+++ b/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java
@@ -39,8 +39,7 @@
  * and <testtype> in {G1,
  *                    Serial,
  *                    Parallel,
- *                    Shenandoah,
- *                    ShenandoahIU}
+ *                    Shenandoah}
  */
 
 
@@ -95,13 +94,6 @@ public void runtest(String classname, String testType) throws Throwable {
             procArgs[argcount - 3] = "-XX:+UnlockExperimentalVMOptions";
             procArgs[argcount - 2] = "-XX:+UseShenandoahGC";
             break;
-        case "ShenandoahIU":
-            argcount = 11;
-            procArgs = new String[argcount];
-            procArgs[argcount - 4] = "-XX:+UnlockExperimentalVMOptions";
-            procArgs[argcount - 3] = "-XX:+UseShenandoahGC";
-            procArgs[argcount - 2] = "-XX:ShenandoahGCMode=iu";
-            break;
         default:
             throw new RuntimeException("unexpected test type " + testType);
         }
@@ -286,7 +278,6 @@ private void checkstore(OutputAnalyzer output, String testType, boolean useCompr
             };
             break;
         case "Shenandoah":
-        case "ShenandoahIU":
              // Shenandoah generates normal object graphs for
              // volatile stores
             matches = new String[] {
@@ -358,7 +349,6 @@ private void checkcas(OutputAnalyzer output, String testType, boolean useCompres
             };
             break;
         case "Shenandoah":
-        case "ShenandoahIU":
             // For volatile CAS, Shenanodoah generates normal
             // graphs with a shenandoah-specific cmpxchg
             matches = new String[] {
@@ -445,7 +435,6 @@ private void checkcae(OutputAnalyzer output, String testType, boolean useCompres
             };
             break;
         case "Shenandoah":
-        case "ShenandoahIU":
             // For volatile CAS, Shenanodoah generates normal
             // graphs with a shenandoah-specific cmpxchg
             matches = new String[] {
@@ -512,7 +501,6 @@ private void checkgas(OutputAnalyzer output, String testType, boolean useCompres
             };
             break;
         case "Shenandoah":
-        case "ShenandoahIU":
             matches = new String[] {
                 "membar_release \\(elided\\)",
                 useCompressedOops ? "atomic_xchgw?_acq" : "atomic_xchg_acq",
diff --git a/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatilesShenandoah.java b/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatilesShenandoah.java
index 9678c37a384..60c9cc3713e 100644
--- a/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatilesShenandoah.java
+++ b/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatilesShenandoah.java
@@ -71,33 +71,6 @@
  * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
  *      TestUnsafeVolatileGAA Shenandoah
  *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestVolatileLoad ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestVolatileStore ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileLoad ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileStore ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileCAS ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileWeakCAS ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileCAE ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileGAS ShenandoahIU
- *
- * @run driver compiler.c2.aarch64.TestVolatilesShenandoah
- *      TestUnsafeVolatileGAA ShenandoahIU
- *
  */
 
 package compiler.c2.aarch64;
diff --git a/test/hotspot/jtreg/compiler/c2/irTests/TestIfMinMax.java b/test/hotspot/jtreg/compiler/c2/irTests/TestIfMinMax.java
index 41402036aea..e232895257a 100644
--- a/test/hotspot/jtreg/compiler/c2/irTests/TestIfMinMax.java
+++ b/test/hotspot/jtreg/compiler/c2/irTests/TestIfMinMax.java
@@ -30,7 +30,7 @@
 
 /*
  * @test
- * @bug 8324655 8329797
+ * @bug 8324655 8329797 8331090
  * @key randomness
  * @summary Test that if expressions are properly folded into min/max nodes
  * @requires os.arch != "riscv64"
@@ -505,7 +505,27 @@ public void checkTestMinLongVector(Object[] vals) {
         }
     }
 
-    @Run(test = { "testMinI1", "testMinI2", "testMaxI1", "testMaxI2", "testMinI1E", "testMinI2E", "testMaxI1E", "testMaxI2E" })
+    @Test
+    @IR(failOn = { IRNode.IF }, counts = { IRNode.MIN_I, "1" })
+    public int testMinIConst(int a) {
+        if (a > 65535) {
+            a = 65535;
+        }
+
+        return a;
+    }
+
+    @Test
+    @IR(phase = { CompilePhase.BEFORE_MACRO_EXPANSION }, failOn = { IRNode.IF }, counts = { IRNode.MIN_L, "1" })
+    public long testMinLConst(long a) {
+        if (a > 65535) {
+            a = 65535;
+        }
+
+        return a;
+    }
+
+    @Run(test = { "testMinI1", "testMinI2", "testMaxI1", "testMaxI2", "testMinI1E", "testMinI2E", "testMaxI1E", "testMaxI2E", "testMinIConst" })
     public void runTestIntegers() {
         testIntegers(10, 20);
         testIntegers(20, 10);
@@ -526,9 +546,12 @@ public void testIntegers(int a, int b) {
         Asserts.assertEQ(a >= b ? b : a, testMinI2E(a, b));
         Asserts.assertEQ(a >= b ? a : b, testMaxI1E(a, b));
         Asserts.assertEQ(a <= b ? b : a, testMaxI2E(a, b));
+
+        Asserts.assertEQ(a > 65535 ? 65535 : a, testMinIConst(a));
+        Asserts.assertEQ(b > 65535 ? 65535 : b, testMinIConst(b));
     }
 
-    @Run(test = { "testMinL1", "testMinL2", "testMaxL1", "testMaxL2", "testMinL1E", "testMinL2E", "testMaxL1E", "testMaxL2E" })
+    @Run(test = { "testMinL1", "testMinL2", "testMaxL1", "testMaxL2", "testMinL1E", "testMinL2E", "testMaxL1E", "testMaxL2E", "testMinLConst" })
     public void runTestLongs() {
         testLongs(10, 20);
         testLongs(20, 10);
@@ -551,5 +574,8 @@ public void testLongs(long a, long b) {
         Asserts.assertEQ(a >= b ? b : a, testMinL2E(a, b));
         Asserts.assertEQ(a >= b ? a : b, testMaxL1E(a, b));
         Asserts.assertEQ(a <= b ? b : a, testMaxL2E(a, b));
+
+        Asserts.assertEQ(a > 65535L ? 65535L : a, testMinLConst(a));
+        Asserts.assertEQ(b > 65535L ? 65535L : b, testMinLConst(b));
     }
 }
diff --git a/test/hotspot/jtreg/compiler/c2/irTests/gc/ReferenceRefersToTests.java b/test/hotspot/jtreg/compiler/c2/irTests/gc/ReferenceRefersToTests.java
new file mode 100644
index 00000000000..7cf7c72c8fd
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/c2/irTests/gc/ReferenceRefersToTests.java
@@ -0,0 +1,156 @@
+/*
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package compiler.c2.irTests.gc;
+
+import jdk.test.lib.Asserts;
+import compiler.lib.ir_framework.*;
+import jdk.test.whitebox.gc.GC;
+
+import java.lang.ref.*;
+import java.util.*;
+
+/*
+ * @test
+ * @bug 8256999
+ * @summary Test that Reference.refersTo intrinsics are properly handled
+ * @library /test/lib /
+ * @build jdk.test.whitebox.WhiteBox
+ * @requires vm.compiler2.enabled
+ * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI compiler.c2.irTests.gc.ReferenceRefersToTests
+ */
+public class ReferenceRefersToTests {
+
+    private static String[] args(String... add) {
+        List<String> args = new ArrayList<>();
+
+         // Use PerMethodTrapLimit=0 to compile all branches in the intrinsics.
+        args.add("-XX:PerMethodTrapLimit=0");
+
+        // Forcefully inline all methods to reach the intrinsic code.
+        args.add("-XX:CompileCommand=inline,compiler.c2.irTests.gc.ReferenceRefersToTests::*");
+        args.add("-XX:CompileCommand=inline,java.lang.ref.Reference::*");
+        args.add("-XX:CompileCommand=inline,java.lang.ref.PhantomReference::*");
+
+        // Mix in test config code.
+        args.addAll(Arrays.asList(add));
+
+        return args.toArray(new String[0]);
+    }
+
+    public static void main(String[] args) {
+        TestFramework framework = new TestFramework();
+
+        int idx = 0;
+        if (GC.isSelectedErgonomically() && GC.Serial.isSupported()) {
+            // Serial does not have any barriers in refersTo.
+            framework.addScenarios(new Scenario(idx++, args(
+                "-XX:+UseSerialGC"
+            )));
+        }
+        if (GC.isSelectedErgonomically() && GC.Parallel.isSupported()) {
+            // Parallel does not have any barriers in refersTo.
+            framework.addScenarios(new Scenario(idx++, args(
+                "-XX:+UseParallelGC"
+            )));
+        }
+        if (GC.isSelectedErgonomically() && GC.G1.isSupported()) {
+            // G1 nominally needs keep-alive barriers for Reference loads,
+            // but should not have them for refersTo.
+            framework.addScenarios(new Scenario(idx++, args(
+                "-XX:+UseG1GC"
+            )));
+        }
+        if (GC.isSelectedErgonomically() && GC.Shenandoah.isSupported()) {
+            // Shenandoah nominally needs keep-alive barriers for Reference loads,
+            // but should not have them for refersTo. We only care to check that
+            // SATB barrier is not emitted. Shenandoah would also emit LRB barrier,
+            // which would false-negative the test.
+            framework.addScenarios(new Scenario(idx++, args(
+                "-XX:+UnlockDiagnosticVMOptions",
+                "-XX:ShenandoahGCMode=passive",
+                "-XX:+ShenandoahSATBBarrier",
+                "-XX:+UseShenandoahGC"
+            )));
+        }
+        if (GC.isSelectedErgonomically() && GC.Z.isSupported()) {
+            // ZGC does not emit barriers in IR.
+            framework.addScenarios(new Scenario(idx++, args(
+                "-XX:+UseZGC"
+            )));
+        }
+        framework.start();
+    }
+
+    static final Object REF = new Object();
+
+    static final SoftReference<Object> SR = new SoftReference<>(REF);
+    static final WeakReference<Object> WR = new WeakReference<>(REF);
+    static final PhantomReference<Object> PR = new PhantomReference<>(REF, null);
+
+    // Verify that we are left with a single load of Reference.referent and no stores.
+    // This serves as a signal that no GC barriers are emitted in IR.
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean soft_null() {
+        return SR.refersTo(null);
+    }
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean soft_ref() {
+        return SR.refersTo(REF);
+    }
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean weak_null() {
+        return WR.refersTo(null);
+    }
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean weak_ref() {
+        return WR.refersTo(REF);
+    }
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean phantom_null() {
+        return PR.refersTo(null);
+    }
+
+    @Test
+    @IR(counts = { IRNode.LOAD, "1" })
+    @IR(failOn = { IRNode.STORE })
+    public boolean phantom_ref() {
+        return PR.refersTo(REF);
+    }
+
+}
diff --git a/test/hotspot/jtreg/compiler/escapeAnalysis/TestFindInstMemRecursion.java b/test/hotspot/jtreg/compiler/escapeAnalysis/TestFindInstMemRecursion.java
new file mode 100644
index 00000000000..90a5ff92cd3
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/escapeAnalysis/TestFindInstMemRecursion.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8324345
+ * @summary Ensure that ConnectionGraph::find_inst_mem does not cause a stack
+ *          overflow.
+ *
+ * @run main/othervm -Xcomp -XX:CompileThreshold=10 -XX:-TieredCompilation
+ *                   -XX:CompileCommand=CompileOnly,javax.swing.plaf.basic.BasicLookAndFeel::initComponentDefaults
+ *                   -XX:CompileCommand=MemLimit,*.*,0
+ *                   compiler.escapeAnalysis.TestFindInstMemRecursion
+ *
+ */
+
+package compiler.escapeAnalysis;
+
+import javax.swing.*;
+import javax.swing.plaf.metal.*;
+
+public class TestFindInstMemRecursion {
+    public static void main(String[] args) throws Exception {
+        LookAndFeel lookAndFeel = new MetalLookAndFeel();
+        for (int i = 0; i < 20; ++i) {
+            UIManager.setLookAndFeel(lookAndFeel);
+        }
+    }
+}
diff --git a/test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java b/test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java
index c7d8d2cf830..e77ac8dc4f9 100644
--- a/test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java
+++ b/test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java
@@ -200,84 +200,4 @@ public void testStackLong() {
         testLongOnStack(compiler);
         testLongInLocal(compiler);
     }
-
-    public static Class<?> objectOnStack() {
-        return SimpleDebugInfoTest.class;
-    }
-
-    private void testObjectOnStack(DebugInfoCompiler compiler) {
-        test(compiler, getMethod("objectOnStack"), 2, JavaKind.Object);
-    }
-
-    public static Class<?> objectInLocal() {
-        Class<?> local = SimpleDebugInfoTest.class;
-        return local;
-    }
-
-    private void testObjectInLocal(DebugInfoCompiler compiler) {
-        test(compiler, getMethod("objectInLocal"), 3, JavaKind.Object);
-    }
-
-    @Test
-    public void testConstObject() {
-        ResolvedJavaType type = metaAccess.lookupJavaType(objectOnStack());
-        DebugInfoCompiler compiler = (asm, values) -> {
-            values[0] = constantReflection.asJavaClass(type);
-            return null;
-        };
-        testObjectOnStack(compiler);
-        testObjectInLocal(compiler);
-    }
-
-    @Test
-    public void testRegObject() {
-        ResolvedJavaType type = metaAccess.lookupJavaType(objectOnStack());
-        DebugInfoCompiler compiler = (asm, values) -> {
-            Register reg = asm.emitLoadPointer((HotSpotConstant) constantReflection.asJavaClass(type));
-            values[0] = reg.asValue(asm.getValueKind(JavaKind.Object));
-            return null;
-        };
-        testObjectOnStack(compiler);
-        testObjectInLocal(compiler);
-    }
-
-    @Test
-    public void testStackObject() {
-        ResolvedJavaType type = metaAccess.lookupJavaType(objectOnStack());
-        DebugInfoCompiler compiler = (asm, values) -> {
-            Register reg = asm.emitLoadPointer((HotSpotConstant) constantReflection.asJavaClass(type));
-            values[0] = asm.emitPointerToStack(reg);
-            return null;
-        };
-        testObjectOnStack(compiler);
-        testObjectInLocal(compiler);
-    }
-
-    @Test
-    public void testRegNarrowObject() {
-        Assume.assumeTrue(config.useCompressedOops);
-        ResolvedJavaType type = metaAccess.lookupJavaType(objectOnStack());
-        DebugInfoCompiler compiler = (asm, values) -> {
-            HotSpotConstant wide = (HotSpotConstant) constantReflection.asJavaClass(type);
-            Register reg = asm.emitLoadPointer((HotSpotConstant) wide.compress());
-            values[0] = reg.asValue(asm.narrowOopKind);
-            return null;
-        };
-        testObjectOnStack(compiler);
-        testObjectInLocal(compiler);
-    }
-
-    @Test
-    public void testStackNarrowObject() {
-        Assume.assumeTrue(config.useCompressedOops);
-        ResolvedJavaType type = metaAccess.lookupJavaType(objectOnStack());
-        DebugInfoCompiler compiler = (asm, values) -> {
-            HotSpotConstant wide = (HotSpotConstant) constantReflection.asJavaClass(type);
-            Register reg = asm.emitLoadPointer((HotSpotConstant) wide.compress());
-            values[0] = asm.emitNarrowPointerToStack(reg);
-            return null;
-        };
-        testObjectOnStack(compiler);
-        testObjectInLocal(compiler);
-    }
 }
diff --git a/test/hotspot/jtreg/compiler/print/CompileCommandPrintMemStat.java b/test/hotspot/jtreg/compiler/print/CompileCommandPrintMemStat.java
index c2689d88372..2dbf46fd040 100644
--- a/test/hotspot/jtreg/compiler/print/CompileCommandPrintMemStat.java
+++ b/test/hotspot/jtreg/compiler/print/CompileCommandPrintMemStat.java
@@ -77,16 +77,17 @@ private static void test(String include, String exclude) throws Exception {
 
         // Should see final report
         // Looks like this:
-        // total     NA        RA        result  #nodes  limit   time    type  #rc thread              method
-        // 2149912   0         1986272   ok      -       -       0.101   c1    1   0x000000015180a600  jdk/internal/org/objectweb/asm/Frame::execute((IILjdk/internal/org/objectweb/asm/Symbol;Ljdk/internal/org/objectweb/asm/SymbolTable;)V)        oa.shouldMatch("total.*method");
+        // total     Others    RA        HA        NA        result  #nodes  limit   time    type  #rc thread             method
+        // 523648    32728     490920    0         0         ok      -       -       0.250   c1    1   0x00007f4ec00d4ac0 java/lang/Class::descriptorString(()Ljava/lang/String;)
         // or
-        // 537784    98184     208536    ok      267     -       0.096   c2    1   0x0000000153019c00  jdk/internal/classfile/impl/BufWriterImpl::writeU1((I)V) 4521912   0         1986272   ok      -       -       0.101   c1    1   0x000000015180a600  jdk/internal/org/objectweb/asm/Frame::execute((IILjdk/internal/org/objectweb/asm/Symbol;Ljdk/internal/org/objectweb/asm/SymbolTable;)V)        oa.shouldMatch("total.*method");
-        oa.shouldMatch("\\d+ +\\d+ +\\d+ +ok +(\\d+|-) +.*" + expectedNameIncl + ".*");
+        // 1898600   853176    750872    0         294552    ok      934     -       1.501   c2    1   0x00007f4ec00d3330 java/lang/String::replace((CC)Ljava/lang/String;)
+        oa.shouldMatch("total.*method");
+        oa.shouldMatch("\\d+ +(\\d+ +){4}ok +(\\d+|-) +.*" + expectedNameIncl + ".*");
 
         // In debug builds, we have a default memory limit enabled. That implies MemStat. Therefore we
         // expect to see all methods, not just the one we specified on the command line.
         if (Platform.isDebugBuild()) {
-            oa.shouldMatch("\\d+ +\\d+ +\\d+ +ok +(\\d+|-) +.*" + expectedNameExcl + ".*");
+            oa.shouldMatch("\\d+ +(\\d+ +){4}ok +(\\d+|-) +.*" + expectedNameExcl + ".*");
         } else {
             oa.shouldNotMatch(".*" + expectedNameExcl + ".*");
         }
diff --git a/test/hotspot/jtreg/compiler/rangechecks/TestEmptyLoopDeadCast.java b/test/hotspot/jtreg/compiler/rangechecks/TestEmptyLoopDeadCast.java
new file mode 100644
index 00000000000..105f297c8cb
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/rangechecks/TestEmptyLoopDeadCast.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2024, Red Hat and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8335393
+ * @summary C2: assert(!had_error) failed: bad dominance
+ * @requires vm.compiler2.enabled
+ * @run main/othervm -XX:-TieredCompilation -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:-UseLoopPredicate
+ *                   -XX:LoopMaxUnroll=0 TestEmptyLoopDeadCast
+ */
+
+public class TestEmptyLoopDeadCast {
+    public static void main(String[] args) {
+        int[] array = new int[100];
+        for (int i = 0; i < 20_000; i++) {
+            test1Helper(1, 101, array);
+            test1(0, array);
+            test2Helper(0, -101, array);
+            test2(0, array);
+        }
+    }
+
+    private static int test1(int start, int[] array) {
+        return test1Helper(start, 0, array);
+    }
+
+    private static int test1Helper(int start, int stop, int[] array) {
+        if (array == null) {
+        }
+        int v = 0;
+        for (int i = start; i < stop; i++) {
+            v = array[i - 1];
+        }
+        return v;
+    }
+
+    private static int test2(int start, int[] array) {
+        return test2Helper(start, -1, array);
+    }
+
+    private static int test2Helper(int start, int stop, int[] array) {
+        if (array == null) {
+        }
+        int v = 0;
+        for (int i = start-1; i > stop; i--) {
+            v = array[-1 - i];
+        }
+        return v;
+    }
+
+}
diff --git a/test/hotspot/jtreg/compiler/vectorapi/VectorReplicateLongSpecialImmTest.java b/test/hotspot/jtreg/compiler/vectorapi/VectorReplicateLongSpecialImmTest.java
index e2ad716d1fa..b885abb632a 100644
--- a/test/hotspot/jtreg/compiler/vectorapi/VectorReplicateLongSpecialImmTest.java
+++ b/test/hotspot/jtreg/compiler/vectorapi/VectorReplicateLongSpecialImmTest.java
@@ -36,7 +36,7 @@
  * @library /test/lib
  * @requires os.arch == "aarch64"
  * @modules jdk.incubator.vector
- * @run testng/othervm -XX:UseSVE=0 -XX:-TieredCompilation -XX:CompileThreshold=100 compiler.vectorapi.VectorReplicateLongSpecialImmTest
+ * @run testng/othervm -XX:UseSVE=0 -XX:-TieredCompilation -XX:CompileThreshold=100 -XX:+IgnoreUnrecognizedVMOptions -XX:CompileCommand=MemLimit,*.*,0 compiler.vectorapi.VectorReplicateLongSpecialImmTest
  */
 public class VectorReplicateLongSpecialImmTest {
 
diff --git a/test/hotspot/jtreg/gc/TestAllocHumongousFragment.java b/test/hotspot/jtreg/gc/TestAllocHumongousFragment.java
index 88b838b4bde..6498a394911 100644
--- a/test/hotspot/jtreg/gc/TestAllocHumongousFragment.java
+++ b/test/hotspot/jtreg/gc/TestAllocHumongousFragment.java
@@ -120,51 +120,6 @@
  *      TestAllocHumongousFragment
  */
 
-/*
- * @test id=iu-aggressive
- * @summary Make sure Shenandoah can recover from humongous allocation fragmentation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot -XX:+ShenandoahVerify
- *      TestAllocHumongousFragment
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot -XX:+ShenandoahVerify
- *      TestAllocHumongousFragment
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestAllocHumongousFragment
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestAllocHumongousFragment
- */
-
-/*
- * @test id=iu
- * @summary Make sure Shenandoah can recover from humongous allocation fragmentation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestAllocHumongousFragment
- *
- * @run main/othervm -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g -XX:ShenandoahTargetNumRegions=2048
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestAllocHumongousFragment
- */
-
  /*
  * @test id=g1
  * @summary Make sure G1 can recover from humongous allocation fragmentation
diff --git a/test/hotspot/jtreg/gc/TestDisableExplicitGC.java b/test/hotspot/jtreg/gc/TestDisableExplicitGC.java
index 9a0b61900dd..08fda78baaa 100644
--- a/test/hotspot/jtreg/gc/TestDisableExplicitGC.java
+++ b/test/hotspot/jtreg/gc/TestDisableExplicitGC.java
@@ -26,6 +26,7 @@
 /*
  * @test TestDisableExplicitGC
  * @requires vm.opt.DisableExplicitGC == null
+ * @requires vm.compMode != "Xcomp"
  * @summary Verify GC behavior with DisableExplicitGC flag.
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
diff --git a/test/hotspot/jtreg/gc/arguments/TestG1PercentageOptions.java b/test/hotspot/jtreg/gc/arguments/TestG1PercentageOptions.java
index e8ee2598c9a..48345da250a 100644
--- a/test/hotspot/jtreg/gc/arguments/TestG1PercentageOptions.java
+++ b/test/hotspot/jtreg/gc/arguments/TestG1PercentageOptions.java
@@ -51,14 +51,14 @@ private static final class OptionDescription {
         }
     }
 
-    private static final String[] defaultValid = new String[] {
-        "0", "1", "50", "95", "100" };
-    private static final String[] defaultInvalid = new String[] {
-        "-10", "110", "bad" };
+    private static final String[] rangeOneToHundredValid = new String[] {
+        "1", "50", "95", "100" };
+    private static final String[] rangeOneToHundredInvalid = new String[] {
+        "0", "-10", "110", "bad" };
 
     // All of the G1 product arguments that are percentages.
     private static final OptionDescription[] percentOptions = new OptionDescription[] {
-        new OptionDescription("G1ConfidencePercent", defaultValid, defaultInvalid)
+        new OptionDescription("G1ConfidencePercent", rangeOneToHundredValid, rangeOneToHundredInvalid)
         // Other percentage options are not yet validated by argument processing.
     };
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java b/test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java
index 35b0cdfa49e..b10e90b4055 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java
@@ -135,56 +135,6 @@
  *      -XX:-UseTLAB -XX:+ShenandoahVerify
  *      TestAllocIntArrays
  */
-
-/*
- * @test id=iu-aggressive
- * @summary Acceptance tests: collector can withstand allocation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot -XX:+ShenandoahVerify
- *      TestAllocIntArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot -XX:+ShenandoahVerify
- *      TestAllocIntArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestAllocIntArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestAllocIntArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestAllocIntArrays
- */
-
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can withstand allocation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestAllocIntArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestAllocIntArrays
- */
-
 import java.util.Random;
 import jdk.test.lib.Utils;
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestAllocObjectArrays.java b/test/hotspot/jtreg/gc/shenandoah/TestAllocObjectArrays.java
index 8eebba4a308..fa9bb7f0177 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestAllocObjectArrays.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestAllocObjectArrays.java
@@ -135,56 +135,6 @@
  *      -XX:-UseTLAB -XX:+ShenandoahVerify
  *      TestAllocObjectArrays
  */
-
-/*
- * @test id=iu-aggressive
- * @summary Acceptance tests: collector can withstand allocation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot -XX:+ShenandoahVerify
- *      TestAllocObjectArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot -XX:+ShenandoahVerify
- *      TestAllocObjectArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestAllocObjectArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestAllocObjectArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestAllocObjectArrays
- */
-
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can withstand allocation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestAllocObjectArrays
- *
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestAllocObjectArrays
- */
-
 import java.util.Random;
 import jdk.test.lib.Utils;
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestAllocObjects.java b/test/hotspot/jtreg/gc/shenandoah/TestAllocObjects.java
index 32178555c9f..26dd98ed403 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestAllocObjects.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestAllocObjects.java
@@ -112,52 +112,6 @@
  *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=compact
  *      TestAllocObjects
  */
-
-/*
- * @test id=iu-aggressive
- * @summary Acceptance tests: collector can withstand allocation
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot -XX:+ShenandoahVerify
- *      TestAllocObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot -XX:+ShenandoahVerify
- *      TestAllocObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestAllocObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestAllocObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestAllocObjects
- */
-
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can withstand allocation
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestAllocObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestAllocObjects
- */
-
 public class TestAllocObjects {
 
     static final long TARGET_MB = Long.getLong("target", 10_000); // 10 Gb allocation
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestDynamicSoftMaxHeapSize.java b/test/hotspot/jtreg/gc/shenandoah/TestDynamicSoftMaxHeapSize.java
index f34fcd8024d..b47a818694f 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestDynamicSoftMaxHeapSize.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestDynamicSoftMaxHeapSize.java
@@ -84,28 +84,6 @@
  *     TestDynamicSoftMaxHeapSize
  */
 
-/*
- * @test id=iu-aggressive
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xms16m -Xmx512m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -Dtarget=1000
- *      TestDynamicSoftMaxHeapSize
- */
-
-/*
- * @test id=iu
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xms16m -Xmx512m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -Dtarget=10000
- *      TestDynamicSoftMaxHeapSize
- */
-
 import java.util.Random;
 import jdk.test.lib.Utils;
 import jdk.test.lib.process.OutputAnalyzer;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestGCThreadGroups.java b/test/hotspot/jtreg/gc/shenandoah/TestGCThreadGroups.java
index ff1596d6833..1e8aaa32dd6 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestGCThreadGroups.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestGCThreadGroups.java
@@ -76,24 +76,6 @@
  *      TestGCThreadGroups
  */
 
-/**
- * @test id=iu
- * @summary Test Shenandoah GC uses concurrent/parallel threads correctly
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:ConcGCThreads=2 -XX:ParallelGCThreads=4
- *      -Dtarget=1000
- *      TestGCThreadGroups
- *
- * @run main/othervm -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:ConcGCThreads=2 -XX:ParallelGCThreads=4
- *      -Dtarget=1000
- *      TestGCThreadGroups
-*/
-
 public class TestGCThreadGroups {
 
     static final long TARGET_MB = Long.getLong("target", 10_000); // 10 Gb allocation, around 1K cycles to handle
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestHeapUncommit.java b/test/hotspot/jtreg/gc/shenandoah/TestHeapUncommit.java
index 6c54a34dae5..a57d9c7c49a 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestHeapUncommit.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestHeapUncommit.java
@@ -84,27 +84,6 @@
  *      TestHeapUncommit
  */
 
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can withstand allocation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahUncommit -XX:ShenandoahUncommitDelay=0
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestHeapUncommit
- *
- * @run main/othervm -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahUncommit -XX:ShenandoahUncommitDelay=0
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestHeapUncommit
- *
- * @run main/othervm -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahUncommit -XX:ShenandoahUncommitDelay=0
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestHeapUncommit
- */
-
 /*
  * @test id=default-lp
  * @key randomness
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestJcmdHeapDump.java b/test/hotspot/jtreg/gc/shenandoah/TestJcmdHeapDump.java
index 40a36d0a5ef..6d8b1cb3875 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestJcmdHeapDump.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestJcmdHeapDump.java
@@ -94,38 +94,6 @@
  *     TestJcmdHeapDump
  */
 
-/*
- * @test id=iu-aggressive
- * @library /test/lib
- * @modules jdk.attach/com.sun.tools.attach
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestJcmdHeapDump
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestJcmdHeapDump
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestJcmdHeapDump
- */
-
-/*
- * @test id=iu
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @modules jdk.attach/com.sun.tools.attach
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestJcmdHeapDump
- */
-
 import jdk.test.lib.JDKToolLauncher;
 import jdk.test.lib.process.ProcessTools;
 import jdk.test.lib.process.OutputAnalyzer;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestLotsOfCycles.java b/test/hotspot/jtreg/gc/shenandoah/TestLotsOfCycles.java
index 63d9fa08767..9d7738c25ce 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestLotsOfCycles.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestLotsOfCycles.java
@@ -91,38 +91,6 @@
  *     TestLotsOfCycles
  */
 
-/*
- * @test id=iu-aggressive
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      -Dtarget=1000
- *      TestLotsOfCycles
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      -Dtarget=1000
- *      TestLotsOfCycles
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -Dtarget=1000
- *      TestLotsOfCycles
- */
-
-/*
- * @test id=iu
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm/timeout=480 -Xmx16m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -Dtarget=10000
- *      TestLotsOfCycles
- */
-
 public class TestLotsOfCycles {
 
     static final long TARGET_MB = Long.getLong("target", 10_000); // 10 Gb allocation, around 1K cycles to handle
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestObjItrWithHeapDump.java b/test/hotspot/jtreg/gc/shenandoah/TestObjItrWithHeapDump.java
index a0612a60a9f..b30f7fd9ac4 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestObjItrWithHeapDump.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestObjItrWithHeapDump.java
@@ -56,7 +56,6 @@ public static void main(String[] args) throws Exception {
 
         String[][][] modeHeuristics = new String[][][] {
              {{"satb"},    {"adaptive", "compact", "static", "aggressive"}},
-             {{"iu"},      {"adaptive", "aggressive"}},
              {{"passive"}, {"passive"}}
         };
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestPeriodicGC.java b/test/hotspot/jtreg/gc/shenandoah/TestPeriodicGC.java
index 3a5780069ef..2849b58aa94 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestPeriodicGC.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestPeriodicGC.java
@@ -97,36 +97,6 @@ public static void main(String[] args) throws Exception {
             );
         }
 
-        testWith("Zero interval with iu mode",
-                 false,
-                 "-Xlog:gc",
-                 "-XX:+UnlockDiagnosticVMOptions",
-                 "-XX:+UnlockExperimentalVMOptions",
-                 "-XX:+UseShenandoahGC",
-                 "-XX:ShenandoahGCMode=iu",
-                 "-XX:ShenandoahGuaranteedGCInterval=0"
-        );
-
-        testWith("Short interval with iu mode",
-                 true,
-                 "-Xlog:gc",
-                 "-XX:+UnlockDiagnosticVMOptions",
-                 "-XX:+UnlockExperimentalVMOptions",
-                 "-XX:+UseShenandoahGC",
-                 "-XX:ShenandoahGCMode=iu",
-                 "-XX:ShenandoahGuaranteedGCInterval=1000"
-        );
-
-        testWith("Long interval with iu mode",
-                 false,
-                 "-Xlog:gc",
-                 "-XX:+UnlockDiagnosticVMOptions",
-                 "-XX:+UnlockExperimentalVMOptions",
-                 "-XX:+UseShenandoahGC",
-                 "-XX:ShenandoahGCMode=iu",
-                 "-XX:ShenandoahGuaranteedGCInterval=100000" // deliberately too long
-        );
-
         testWith("Short interval with aggressive",
                  false,
                  "-Xlog:gc",
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestReferenceRefersToShenandoah.java b/test/hotspot/jtreg/gc/shenandoah/TestReferenceRefersToShenandoah.java
index 8bad2fdbfa4..3763a7eea87 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestReferenceRefersToShenandoah.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestReferenceRefersToShenandoah.java
@@ -35,18 +35,6 @@
  *      gc.shenandoah.TestReferenceRefersToShenandoah
  */
 
-/* @test id=iu
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @build jdk.test.whitebox.WhiteBox
- * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
- * @run main/othervm
- *      -Xbootclasspath/a:.
- *      -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
- *      -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      gc.shenandoah.TestReferenceRefersToShenandoah
- */
-
 /* @test id=satb-100
  * @requires vm.gc.Shenandoah
  * @library /test/lib
@@ -60,19 +48,6 @@
  *      gc.shenandoah.TestReferenceRefersToShenandoah
  */
 
-/* @test id=iu-100
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @build jdk.test.whitebox.WhiteBox
- * @modules java.base
- * @run main jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
- * @run main/othervm
- *      -Xbootclasspath/a:.
- *      -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
- *      -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGarbageThreshold=100 -Xmx100m
- *      gc.shenandoah.TestReferenceRefersToShenandoah
- */
-
 import java.lang.ref.PhantomReference;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
@@ -200,10 +175,6 @@ private static void discardStrongReferences() {
         testObject4 = null;
     }
 
-    private static boolean isShenandoahIUMode() {
-        return "iu".equals(WB.getStringVMFlag("ShenandoahGCMode"));
-    }
-
     private static void testConcurrentCollection() throws Exception {
         progress("setup concurrent collection test");
         setup();
@@ -239,14 +210,7 @@ private static void testConcurrentCollection() throws Exception {
             expectCleared(testPhantom1, "testPhantom1");
             expectCleared(testWeak2, "testWeak2");
             expectValue(testWeak3, testObject3, "testWeak3");
-            // This is true for all currently supported concurrent collectors,
-            // except Shenandoah+IU, which allows clearing refs even when
-            // accessed during concurrent marking.
-            if (isShenandoahIUMode()) {
-              expectCleared(testWeak4, "testWeak4");
-            } else {
-              expectNotCleared(testWeak4, "testWeak4");
-            }
+            expectNotCleared(testWeak4, "testWeak4");
 
             progress("verify get returns expected values");
             if (testWeak2.get() != null) {
@@ -261,12 +225,10 @@ private static void testConcurrentCollection() throws Exception {
             }
 
             TestObject obj4 = testWeak4.get();
-            if (!isShenandoahIUMode()) {
-                if (obj4 == null) {
-                    fail("testWeak4.get() returned null");
-                } else if (obj4.value != 4) {
-                    fail("testWeak4.get().value is " + obj4.value);
-                }
+            if (obj4 == null) {
+                fail("testWeak4.get() returned null");
+            } else if (obj4.value != 4) {
+                fail("testWeak4.get().value is " + obj4.value);
             }
 
             progress("verify queue entries");
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestReferenceShortcutCycle.java b/test/hotspot/jtreg/gc/shenandoah/TestReferenceShortcutCycle.java
index 1c2c2ed5ca7..b7ae0c1c31a 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestReferenceShortcutCycle.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestReferenceShortcutCycle.java
@@ -36,19 +36,6 @@
  *      gc.shenandoah.TestReferenceShortcutCycle
  */
 
-/* @test id=iu-100
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @build jdk.test.whitebox.WhiteBox
- * @modules java.base
- * @run main jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
- * @run main/othervm
- *      -Xbootclasspath/a:.
- *      -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
- *      -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGarbageThreshold=100 -Xmx100m
- *      gc.shenandoah.TestReferenceShortcutCycle
- */
-
 import java.lang.ref.PhantomReference;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestRefprocSanity.java b/test/hotspot/jtreg/gc/shenandoah/TestRefprocSanity.java
index 03f008d10c3..0bf7672e7d5 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestRefprocSanity.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestRefprocSanity.java
@@ -41,25 +41,6 @@
  *      TestRefprocSanity
  */
 
-/*
- * @test id=iu
- * @summary Test that null references/referents work fine
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx128m -Xms128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestRefprocSanity
- *
- * @run main/othervm -Xmx128m -Xms128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestRefprocSanity
- *
- * @run main/othervm -Xmx128m -Xms128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestRefprocSanity
- */
-
 import java.lang.ref.*;
 
 public class TestRefprocSanity {
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestRegionSampling.java b/test/hotspot/jtreg/gc/shenandoah/TestRegionSampling.java
index dd98585181c..dfa09a2f5ab 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestRegionSampling.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestRegionSampling.java
@@ -73,25 +73,6 @@
  *      TestRegionSampling
  */
 
-/*
- * @test id=iu-aggressive
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahRegionSampling
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestRegionSampling
- */
-
-/*
- * @test id=iu
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahRegionSampling
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestRegionSampling
- *
- */
-
 public class TestRegionSampling {
 
     static final long TARGET_MB = Long.getLong("target", 2_000); // 2 Gb allocation
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestResizeTLAB.java b/test/hotspot/jtreg/gc/shenandoah/TestResizeTLAB.java
index 095f9939569..4e3089d0862 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestResizeTLAB.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestResizeTLAB.java
@@ -138,46 +138,6 @@
  *      TestResizeTLAB
  */
 
-/*
- * @test id=iu-aggressive
- * @key randomness
- * @summary Test that Shenandoah is able to work with(out) resizeable TLABs
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahVerify
- *      -XX:+ResizeTLAB
- *      TestResizeTLAB
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahVerify
- *      -XX:-ResizeTLAB
- *      TestResizeTLAB
- */
-
-/*
- * @test id=iu
- * @key randomness
- * @summary Test that Shenandoah is able to work with(out) resizeable TLABs
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      -XX:+ResizeTLAB
- *      TestResizeTLAB
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      -XX:-ResizeTLAB
- *      TestResizeTLAB
- */
-
 import java.util.Random;
 import jdk.test.lib.Utils;
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestRetainObjects.java b/test/hotspot/jtreg/gc/shenandoah/TestRetainObjects.java
index 7a28548f610..7be388b7945 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestRetainObjects.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestRetainObjects.java
@@ -114,41 +114,6 @@
  *      TestRetainObjects
  */
 
-/*
- * @test id=iu-aggressive
- * @summary Acceptance tests: collector can deal with retained objects
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestRetainObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestRetainObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestRetainObjects
- */
-
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can deal with retained objects
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestRetainObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestRetainObjects
- */
-
 public class TestRetainObjects {
 
     static final int COUNT = 10_000_000;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestSieveObjects.java b/test/hotspot/jtreg/gc/shenandoah/TestSieveObjects.java
index 1b16ba4b8d2..2eaead55a6a 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestSieveObjects.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestSieveObjects.java
@@ -127,45 +127,6 @@
  *      TestSieveObjects
  */
 
-/*
- * @test id=iu-aggressive
- * @summary Acceptance tests: collector can deal with retained objects
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      TestSieveObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      TestSieveObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestSieveObjects
- */
-
-/*
- * @test id=iu
- * @summary Acceptance tests: collector can deal with retained objects
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestSieveObjects
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestSieveObjects
- */
-
 import java.util.Random;
 import jdk.test.lib.Utils;
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestStringDedup.java b/test/hotspot/jtreg/gc/shenandoah/TestStringDedup.java
index 94691432f38..9fdb822d48c 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestStringDedup.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestStringDedup.java
@@ -65,24 +65,6 @@
  *      TestStringDedup
  */
 
-/*
- * @test id=iu
- * @summary Test Shenandoah string deduplication implementation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @modules java.base/java.lang:open
- *          java.management
- *
- * @run main/othervm -Xmx256m -Xlog:gc+stats -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:StringDeduplicationAgeThreshold=3
- *      TestStringDedup
- *
- * @run main/othervm -Xmx256m -Xlog:gc+stats -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive -XX:StringDeduplicationAgeThreshold=3
- *      TestStringDedup
- */
-
 import java.lang.reflect.*;
 import java.util.*;
 import jdk.test.lib.Utils;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestStringDedupStress.java b/test/hotspot/jtreg/gc/shenandoah/TestStringDedupStress.java
index 0382d0e00dd..2d928e848ce 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestStringDedupStress.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestStringDedupStress.java
@@ -72,37 +72,6 @@
  *      TestStringDedupStress
  */
 
- /*
- * @test id=iu
- * @summary Test Shenandoah string deduplication implementation
- * @key randomness
- * @requires vm.gc.Shenandoah
- * @library /test/lib
- * @modules java.base/java.lang:open
- *          java.management
- *
- * @run main/othervm -Xmx1g -Xlog:gc+stats -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestStringDedupStress
- *
- * @run main/othervm -Xmx1g -Xlog:gc+stats -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -DtargetStrings=2000000
- *      TestStringDedupStress
- *
- * @run main/othervm -Xmx1g -Xlog:gc+stats -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      -DtargetStrings=2000000
- *      TestStringDedupStress
- *
- * @run main/othervm -Xmx1g -Xlog:gc+stats -Xlog:gc -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseStringDeduplication
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      -DtargetStrings=2000000
- *      TestStringDedupStress
- */
-
 import java.lang.management.*;
 import java.lang.reflect.*;
 import java.util.*;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestStringInternCleanup.java b/test/hotspot/jtreg/gc/shenandoah/TestStringInternCleanup.java
index cf663f2329c..62c9e16f777 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestStringInternCleanup.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestStringInternCleanup.java
@@ -75,26 +75,6 @@
  *      TestStringInternCleanup
  */
 
-/*
- * @test id=iu
- * @summary Check that Shenandoah cleans up interned strings
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ClassUnloadingWithConcurrentMark
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestStringInternCleanup
- *
- * @run main/othervm -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ClassUnloadingWithConcurrentMark
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahVerify
- *      TestStringInternCleanup
- *
- * @run main/othervm -Xmx64m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+ClassUnloadingWithConcurrentMark
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestStringInternCleanup
- */
-
 public class TestStringInternCleanup {
 
     static final int COUNT = 1_000_000;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestVerifyJCStress.java b/test/hotspot/jtreg/gc/shenandoah/TestVerifyJCStress.java
index 312ab964f5e..82bc74daddc 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestVerifyJCStress.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestVerifyJCStress.java
@@ -58,33 +58,6 @@
  *      TestVerifyJCStress
  */
 
-/*
- * @test id=iu
- * @summary Tests that we pass at least one jcstress-like test with all verification turned on
- * @requires vm.gc.Shenandoah
- * @modules java.base/jdk.internal.misc
- *          java.management
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      TestVerifyJCStress
- */
-
-/*
- * @test id=iu-c1
- * @summary Tests that we pass at least one jcstress-like test with all verification turned on
- * @requires vm.gc.Shenandoah
- * @modules java.base/jdk.internal.misc
- *          java.management
- *
- * @run main/othervm -Xmx1g -Xms1g -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify -XX:TieredStopAtLevel=1
- *      TestVerifyJCStress
- */
-
-
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.locks.*;
diff --git a/test/hotspot/jtreg/gc/shenandoah/TestWrongArrayMember.java b/test/hotspot/jtreg/gc/shenandoah/TestWrongArrayMember.java
index 6712cb49561..6dcdf259c6c 100644
--- a/test/hotspot/jtreg/gc/shenandoah/TestWrongArrayMember.java
+++ b/test/hotspot/jtreg/gc/shenandoah/TestWrongArrayMember.java
@@ -26,8 +26,7 @@
  * @test
  * @requires vm.gc.Shenandoah
  *
- * @run main/othervm -Xmx128m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC                         TestWrongArrayMember
- * @run main/othervm -Xmx128m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu TestWrongArrayMember
+ * @run main/othervm -Xmx128m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC TestWrongArrayMember
  */
 
 public class TestWrongArrayMember {
diff --git a/test/hotspot/jtreg/gc/shenandoah/compiler/BarrierInInfiniteLoop.java b/test/hotspot/jtreg/gc/shenandoah/compiler/BarrierInInfiniteLoop.java
index 8673005f96f..9054c1f470e 100644
--- a/test/hotspot/jtreg/gc/shenandoah/compiler/BarrierInInfiniteLoop.java
+++ b/test/hotspot/jtreg/gc/shenandoah/compiler/BarrierInInfiniteLoop.java
@@ -30,8 +30,6 @@
  *
  * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xcomp -XX:CompileOnly=BarrierInInfiniteLoop::test1
  *                   -XX:CompileOnly=BarrierInInfiniteLoop::test2 -XX:CompileOnly=BarrierInInfiniteLoop::test3 -XX:CompileCommand=quiet BarrierInInfiniteLoop
- * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -Xcomp -XX:CompileOnly=BarrierInInfiniteLoop::test1
- *                   -XX:CompileOnly=BarrierInInfiniteLoop::test2 -XX:CompileOnly=BarrierInInfiniteLoop::test3 -XX:CompileCommand=quiet BarrierInInfiniteLoop
  *
  */
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/compiler/TestUnexpectedIUBarrierEA.java b/test/hotspot/jtreg/gc/shenandoah/compiler/TestUnexpectedIUBarrierEA.java
deleted file mode 100644
index 8662130c378..00000000000
--- a/test/hotspot/jtreg/gc/shenandoah/compiler/TestUnexpectedIUBarrierEA.java
+++ /dev/null
@@ -1,74 +0,0 @@
-/*
- * Copyright (c) 2022, Red Hat, Inc. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/*
- * @test
- * bug 8280885
- * @summary Shenandoah: Some tests failed with "EA: missing allocation reference path"
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -XX:-BackgroundCompilation -XX:+UseShenandoahGC -XX:+UnlockExperimentalVMOptions -XX:ShenandoahGCMode=iu
- *                   -XX:CompileCommand=dontinline,TestUnexpectedIUBarrierEA::notInlined TestUnexpectedIUBarrierEA
- */
-
-public class TestUnexpectedIUBarrierEA {
-
-    private static Object field;
-
-    public static void main(String[] args) {
-        for (int i = 0; i < 20_000; i++) {
-            test(false);
-        }
-    }
-
-    private static void test(boolean flag) {
-        A a = new A();
-        B b = new B();
-        b.field = a;
-        notInlined();
-        Object o = b.field;
-        if (!(o instanceof A)) {
-
-        }
-        C c = new C();
-        c.field = o;
-        if (flag) {
-            field = c.field;
-        }
-    }
-
-    private static void notInlined() {
-
-    }
-
-    private static class A {
-    }
-
-    private static class B {
-        public Object field;
-    }
-
-    private static class C {
-        public Object field;
-    }
-}
diff --git a/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestChurnNotifications.java b/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestChurnNotifications.java
index 96586b27f65..73743aadedc 100644
--- a/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestChurnNotifications.java
+++ b/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestChurnNotifications.java
@@ -87,23 +87,6 @@
  *      TestChurnNotifications
  */
 
-/*
- * @test id=iu
- * @summary Check that MX notifications are reported for all cycles
- * @library /test/lib /
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -Dprecise=false
- *      TestChurnNotifications
- *
- * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -Dprecise=false
- *      TestChurnNotifications
- */
-
 import java.util.*;
 import java.util.concurrent.atomic.*;
 import javax.management.*;
diff --git a/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestPauseNotifications.java b/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestPauseNotifications.java
index 0919a21d370..2dd9aba4c62 100644
--- a/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestPauseNotifications.java
+++ b/test/hotspot/jtreg/gc/shenandoah/mxbeans/TestPauseNotifications.java
@@ -83,21 +83,6 @@
  *      TestPauseNotifications
  */
 
-/*
- * @test id=iu
- * @summary Check that MX notifications are reported for all cycles
- * @library /test/lib /
- * @requires vm.gc.Shenandoah
- *
- * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      TestPauseNotifications
- *
- * @run main/othervm -Xmx128m -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      TestPauseNotifications
- */
-
 import java.util.*;
 import java.util.concurrent.atomic.*;
 import javax.management.*;
diff --git a/test/hotspot/jtreg/gc/shenandoah/oom/TestClassLoaderLeak.java b/test/hotspot/jtreg/gc/shenandoah/oom/TestClassLoaderLeak.java
index 9d17e916089..1a3d07bf80d 100644
--- a/test/hotspot/jtreg/gc/shenandoah/oom/TestClassLoaderLeak.java
+++ b/test/hotspot/jtreg/gc/shenandoah/oom/TestClassLoaderLeak.java
@@ -124,7 +124,6 @@ public static void main(String[] args) throws Exception {
 
         String[][][] modeHeuristics = new String[][][] {
              {{"satb"},    {"adaptive", "compact", "static", "aggressive"}},
-             {{"iu"},      {"adaptive", "aggressive"}},
              {{"passive"}, {"passive"}}
         };
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/options/TestExplicitGC.java b/test/hotspot/jtreg/gc/shenandoah/options/TestExplicitGC.java
index 7fe5d56f7de..4effff7ebd5 100644
--- a/test/hotspot/jtreg/gc/shenandoah/options/TestExplicitGC.java
+++ b/test/hotspot/jtreg/gc/shenandoah/options/TestExplicitGC.java
@@ -125,23 +125,5 @@ public static void main(String[] args) throws Exception {
                 output.shouldNotContain(p);
             }
         }
-
-        {
-            OutputAnalyzer output = ProcessTools.executeLimitedTestJava(
-                    "-Xmx128m",
-                    "-XX:+UnlockExperimentalVMOptions",
-                    "-XX:+UseShenandoahGC",
-                    "-Xlog:gc",
-                    "-XX:+ExplicitGCInvokesConcurrent",
-                    "-XX:ShenandoahGCMode=iu",
-                    TestExplicitGC.class.getName(),
-                    "test");
-            for (String p : full) {
-                output.shouldNotContain(p);
-            }
-            for (String p : concNormal) {
-                output.shouldContain(p);
-            }
-         }
     }
 }
diff --git a/test/hotspot/jtreg/gc/shenandoah/options/TestModeUnlock.java b/test/hotspot/jtreg/gc/shenandoah/options/TestModeUnlock.java
index 802038363b5..5422a86a496 100644
--- a/test/hotspot/jtreg/gc/shenandoah/options/TestModeUnlock.java
+++ b/test/hotspot/jtreg/gc/shenandoah/options/TestModeUnlock.java
@@ -45,7 +45,6 @@ enum Mode {
 
     public static void main(String[] args) throws Exception {
         testWith("-XX:ShenandoahGCMode=satb",    Mode.PRODUCT);
-        testWith("-XX:ShenandoahGCMode=iu",      Mode.EXPERIMENTAL);
         testWith("-XX:ShenandoahGCMode=passive", Mode.DIAGNOSTIC);
     }
 
diff --git a/test/hotspot/jtreg/gc/shenandoah/options/TestSelectiveBarrierFlags.java b/test/hotspot/jtreg/gc/shenandoah/options/TestSelectiveBarrierFlags.java
index 094e62f53f3..fe29a38c422 100644
--- a/test/hotspot/jtreg/gc/shenandoah/options/TestSelectiveBarrierFlags.java
+++ b/test/hotspot/jtreg/gc/shenandoah/options/TestSelectiveBarrierFlags.java
@@ -50,7 +50,7 @@ public class TestSelectiveBarrierFlags {
     public static void main(String[] args) throws Exception {
         String[][] opts = {
                 new String[] { "ShenandoahLoadRefBarrier" },
-                new String[] { "ShenandoahSATBBarrier", "ShenandoahIUBarrier" },
+                new String[] { "ShenandoahSATBBarrier" },
                 new String[] { "ShenandoahCASBarrier" },
                 new String[] { "ShenandoahCloneBarrier" },
                 new String[] { "ShenandoahStackWatermarkBarrier" }
diff --git a/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierDisable.java b/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierDisable.java
index aa6b7935649..9bf1e745856 100644
--- a/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierDisable.java
+++ b/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierDisable.java
@@ -44,21 +44,12 @@ public static void main(String[] args) throws Exception {
                 "ShenandoahCloneBarrier",
                 "ShenandoahStackWatermarkBarrier",
         };
-        String[] iu = {
-                "ShenandoahLoadRefBarrier",
-                "ShenandoahIUBarrier",
-                "ShenandoahCASBarrier",
-                "ShenandoahCloneBarrier",
-                "ShenandoahStackWatermarkBarrier",
-        };
 
         shouldFailAll("-XX:ShenandoahGCHeuristics=adaptive",   concurrent);
         shouldFailAll("-XX:ShenandoahGCHeuristics=static",     concurrent);
         shouldFailAll("-XX:ShenandoahGCHeuristics=compact",    concurrent);
         shouldFailAll("-XX:ShenandoahGCHeuristics=aggressive", concurrent);
-        shouldFailAll("-XX:ShenandoahGCMode=iu",               iu);
         shouldPassAll("-XX:ShenandoahGCMode=passive",          concurrent);
-        shouldPassAll("-XX:ShenandoahGCMode=passive",          iu);
     }
 
     private static void shouldFailAll(String h, String[] barriers) throws Exception {
diff --git a/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierEnable.java b/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierEnable.java
index 486860728ab..ea64d3ee712 100644
--- a/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierEnable.java
+++ b/test/hotspot/jtreg/gc/shenandoah/options/TestWrongBarrierEnable.java
@@ -23,7 +23,7 @@
  */
 
 /* @test
- * @summary Test that disabling wrong barriers fails early
+ * @summary Test that SATB barrier may be enabled for all modes
  * @requires vm.gc.Shenandoah
  * @library /test/lib
  * @run driver TestWrongBarrierEnable
@@ -38,19 +38,13 @@ public class TestWrongBarrierEnable {
 
     public static void main(String[] args) throws Exception {
         String[] concurrent = {
-                "ShenandoahIUBarrier",
-        };
-        String[] iu = {
                 "ShenandoahSATBBarrier",
         };
-
-        shouldFailAll("-XX:ShenandoahGCHeuristics=adaptive",   concurrent);
-        shouldFailAll("-XX:ShenandoahGCHeuristics=static",     concurrent);
-        shouldFailAll("-XX:ShenandoahGCHeuristics=compact",    concurrent);
-        shouldFailAll("-XX:ShenandoahGCHeuristics=aggressive", concurrent);
-        shouldFailAll("-XX:ShenandoahGCMode=iu",               iu);
+        shouldPassAll("-XX:ShenandoahGCHeuristics=adaptive",   concurrent);
+        shouldPassAll("-XX:ShenandoahGCHeuristics=static",     concurrent);
+        shouldPassAll("-XX:ShenandoahGCHeuristics=compact",    concurrent);
+        shouldPassAll("-XX:ShenandoahGCHeuristics=aggressive", concurrent);
         shouldPassAll("-XX:ShenandoahGCMode=passive",          concurrent);
-        shouldPassAll("-XX:ShenandoahGCMode=passive",          iu);
     }
 
     private static void shouldFailAll(String h, String[] barriers) throws Exception {
diff --git a/test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithShenandoah.java b/test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithShenandoah.java
index 6e98f99b548..501605cd0f5 100644
--- a/test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithShenandoah.java
+++ b/test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithShenandoah.java
@@ -99,47 +99,6 @@
  *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
  */
 
-/*
- * @test id=iu-aggressive
- * @key stress
- * @library /
- * @requires vm.gc.Shenandoah
- * @requires vm.flavor == "server" & !vm.emulatedClient
- * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- */
-
-/*
- * @test id=iu
- * @key stress
- * @library /
- * @requires vm.gc.Shenandoah
- * @requires vm.flavor == "server" & !vm.emulatedClient
- * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- */
-
 /*
  * @test id=passive-deopt-nmethod
  * @key stress
@@ -221,53 +180,6 @@
  *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
  */
 
-/*
- * @test id=iu-aggressive-deopt-nmethod
- * @key stress
- * @library /
- * @requires vm.gc.Shenandoah
- * @requires vm.flavor == "server" & !vm.emulatedClient & vm.opt.ClassUnloading != false
- * @summary Stress Shenandoah GC with nmethod barrier forced deoptimization enabled.
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info,nmethod+barrier=trace -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+DeoptimizeNMethodBarriersALot -XX:-Inline
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info,nmethod+barrier=trace -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+DeoptimizeNMethodBarriersALot -XX:-Inline
- *      -XX:+ShenandoahAllocFailureALot
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info,nmethod+barrier=trace -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+DeoptimizeNMethodBarriersALot -XX:-Inline
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- */
-
-/*
- * @test id=iu-deopt-nmethod
- * @key stress
- * @library /
- * @requires vm.gc.Shenandoah
- * @requires vm.flavor == "server" & !vm.emulatedClient & vm.opt.ClassUnloading != false
- * @summary Stress Shenandoah GC with nmethod barrier forced deoptimization enabled.
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info,nmethod+barrier=trace -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+DeoptimizeNMethodBarriersALot -XX:-Inline
- *      -XX:+ShenandoahVerify
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- *
- * @run main/othervm/timeout=200 -Xlog:gc*=info,nmethod+barrier=trace -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+DeoptimizeNMethodBarriersALot -XX:-Inline
- *      gc.stress.gcbasher.TestGCBasherWithShenandoah 120000
- */
-
-
 public class TestGCBasherWithShenandoah {
     public static void main(String[] args) throws IOException {
         TestGCBasher.main(args);
diff --git a/test/hotspot/jtreg/gc/stress/gcold/TestGCOldWithShenandoah.java b/test/hotspot/jtreg/gc/stress/gcold/TestGCOldWithShenandoah.java
index f1e34bb1b0b..7b9794ec4db 100644
--- a/test/hotspot/jtreg/gc/stress/gcold/TestGCOldWithShenandoah.java
+++ b/test/hotspot/jtreg/gc/stress/gcold/TestGCOldWithShenandoah.java
@@ -102,45 +102,6 @@
  *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
  */
 
-/*
- * @test id=iu-aggressive
- * @key stress randomness
- * @library / /test/lib
- * @requires vm.gc.Shenandoah
- * @summary Stress the GC by trying to make old objects more likely to be garbage than young objects.
- *
- * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahOOMDuringEvacALot
- *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
- *
- * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      -XX:+ShenandoahAllocFailureALot
- *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
- *
- * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu -XX:ShenandoahGCHeuristics=aggressive
- *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
- */
-
-/*
- * @test id=iu
- * @key stress randomness
- * @library / /test/lib
- * @requires vm.gc.Shenandoah
- * @summary Stress the GC by trying to make old objects more likely to be garbage than young objects.
- *
- * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
- *
- * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      gc.stress.gcold.TestGCOld 50 1 20 10 10000
- */
-
 public class TestGCOldWithShenandoah {
 
     public static void main(String[] args) {
diff --git a/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithShenandoah.java b/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithShenandoah.java
index 1b12e22b62f..f1b743bfc15 100644
--- a/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithShenandoah.java
+++ b/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithShenandoah.java
@@ -40,20 +40,6 @@
  *      -XX:+UseShenandoahGC
  *      gc.stress.systemgc.TestSystemGCWithShenandoah 270
  */
-
-/*
- * @test id=iu
- * @key stress
- * @library /
- * @requires vm.gc.Shenandoah
- * @summary Stress the Shenandoah GC full GC by allocating objects of different lifetimes concurrently with System.gc().
- *
- * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
- *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=iu
- *      -XX:+ShenandoahVerify
- *      gc.stress.systemgc.TestSystemGCWithShenandoah 270
- *
- */
 public class TestSystemGCWithShenandoah {
     public static void main(String[] args) throws Exception {
         TestSystemGC.main(args);
diff --git a/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestDumpBase.java b/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestDumpBase.java
index ad7b8e97b81..eedefaa1ba1 100644
--- a/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestDumpBase.java
+++ b/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestDumpBase.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -190,6 +190,10 @@ protected static OutputAnalyzer test(String fileName, long pid,
         PidJcmdExecutor cmdExecutor = new PidJcmdExecutor(String.valueOf(pid));
         OutputAnalyzer output = cmdExecutor.execute(jcmd, true/*silent*/);
 
+        if (archiveFileName.contains("%p")) {
+            archiveFileName = archiveFileName.replace("%p", "%d").formatted(pid);
+        }
+
         if (expectOK) {
             output.shouldHaveExitValue(0);
             checkFileExistence(archiveFileName, true);
diff --git a/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestStaticDump.java b/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestStaticDump.java
index a95eaf672c1..08ccf9b7f2a 100644
--- a/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestStaticDump.java
+++ b/test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestStaticDump.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -87,6 +87,13 @@ static void test() throws Exception {
         }
         app.stopApp();
 
+        // Test static dump with file name containing %p
+        print2ln(test_count++ + " Test static dump with given file name containing %p.");
+        app = createLingeredApp("-cp", allJars);
+        pid = app.getPid();
+        test("%p.jsa", pid, noBoot, EXPECT_PASS, STATIC_MESSAGES);
+        app.stopApp();
+
         //  Test static dump with flags with which dumping should fail
         //  This test will result classes.jsa in default server dir if -XX:SharedArchiveFile= not set.
         print2ln(test_count++ + " Test static dump with flags with which dumping should fail.");
diff --git a/test/hotspot/jtreg/serviceability/ParserTest.java b/test/hotspot/jtreg/serviceability/ParserTest.java
index 70d666d2ed0..7c304af243c 100644
--- a/test/hotspot/jtreg/serviceability/ParserTest.java
+++ b/test/hotspot/jtreg/serviceability/ParserTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,7 @@
 
 import java.math.BigInteger;
 
+import jdk.test.lib.process.ProcessTools;
 import jdk.test.whitebox.parser.DiagnosticCommand;
 import jdk.test.whitebox.parser.DiagnosticCommand.DiagnosticArgumentType;
 import jdk.test.whitebox.WhiteBox;
@@ -49,6 +50,7 @@ public ParserTest() throws Exception {
         testQuotes();
         testMemorySize();
         testSingleLetterArg();
+        testFileName();
     }
 
     public static void main(String... args) throws Exception  {
@@ -159,6 +161,33 @@ public void testSingleLetterArg() throws Exception {
         parse("value", "v", "flag v", ' ', args);
     }
 
+    public void testFileName() throws Exception {
+        // --- Testing options
+        long pid = ProcessTools.getProcessId();
+
+        // Test pid gets injected into %p
+        String name = "name";
+        DiagnosticCommand arg = new DiagnosticCommand(name,
+                "desc", DiagnosticArgumentType.FILE,
+                false, null);
+        DiagnosticCommand[] args = {arg};
+        parse(name, "file%d.txt".formatted(pid), name + "=file%p.txt", args);
+
+        // Test custom file name with no %p
+        parse(name, "myFile.txt", name + "=myFile.txt", args);
+
+        // --- Testing arguments
+
+        // Test pid gets injected into %p
+        arg = new DiagnosticCommand(name, "desc", DiagnosticArgumentType.FILE, true,
+                false, null);
+        args = new DiagnosticCommand[]{arg};
+        parse(name, "file%d.txt".formatted(pid), "file%p.txt", args);
+
+        // Test custom file name with no %p
+        parse(name, "myFile.txt", "myFile.txt", args);
+    }
+
     public void testMemorySize() throws Exception {
         String name = "name";
         String defaultValue = "1024";
diff --git a/test/hotspot/jtreg/serviceability/dcmd/compiler/CompilerMemoryStatisticTest.java b/test/hotspot/jtreg/serviceability/dcmd/compiler/CompilerMemoryStatisticTest.java
index 7d4a38db47b..02bc77263d8 100644
--- a/test/hotspot/jtreg/serviceability/dcmd/compiler/CompilerMemoryStatisticTest.java
+++ b/test/hotspot/jtreg/serviceability/dcmd/compiler/CompilerMemoryStatisticTest.java
@@ -47,9 +47,9 @@ public static void main(String args[]) throws Exception {
         out.shouldHaveExitValue(0);
 
         // Looks like this:
-        // total     NA        RA        result  #nodes  time    type  #rc thread              method
-        // 211488    66440     77624     ok      13      0.057   c2    2   0x00007fb49428db70  compiler/print/CompileCommandPrintMemStat$TestMain::method1(()V)
+        // total     Others    RA        HA        NA        result  #nodes  limit   time    type  #rc thread             method
+        // 1898600   853176    750872    0         294552    ok      934     -       1.501   c2    1   0x00007f4ec00d3330 java/lang/String::replace((CC)Ljava/lang/String;)
         out.shouldMatch("total.*method");
-        out.shouldMatch("\\d+ +\\d+ +\\d+ +\\S+ +\\d+.*java.*\\(.*\\)");
+        out.shouldMatch("\\d+ +(\\d+ +){4}\\S+ +\\d+.*java.*\\(.*\\)");
     }
 }
diff --git a/test/hotspot/jtreg/serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java b/test/hotspot/jtreg/serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java
index 80ca790a11d..420f1cedaca 100644
--- a/test/hotspot/jtreg/serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java
+++ b/test/hotspot/jtreg/serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,7 +24,7 @@
 
 /**
  * @test
- * @bug 8185164 8320515
+ * @bug 8185164 8320515 8334085
  * @summary Checks that a contended monitor does not show up in the list of owned monitors.
  *          8320515 piggy-backs on this test and injects an owned monitor with a dead object,
             and checks that that monitor isn't exposed to GetOwnedMonitorInfo.
@@ -86,6 +86,9 @@ public static void runTest(boolean isVirtual, boolean jni) throws Exception {
                 System.out.println("Thread doing JNI call: "
                                    + Thread.currentThread().getName());
 
+                // Extra unmount helps to reproduce 8334085.
+                // Two sub-sequential thaws are needed in that scenario.
+                Thread.yield();
                 jniMonitorEnterAndLetObjectDie();
             }
 
diff --git a/test/hotspot/jtreg/serviceability/jvmti/thread/GetFrameCount/framecnt01/framecnt01.java b/test/hotspot/jtreg/serviceability/jvmti/thread/GetFrameCount/framecnt01/framecnt01.java
index 8d757283a30..8a7177ec25d 100644
--- a/test/hotspot/jtreg/serviceability/jvmti/thread/GetFrameCount/framecnt01/framecnt01.java
+++ b/test/hotspot/jtreg/serviceability/jvmti/thread/GetFrameCount/framecnt01/framecnt01.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -79,7 +79,7 @@ public static void main(String args[]) throws Exception {
         }
 
         // this is too fragile, implementation can change at any time.
-        checkFrames(vThread1, false, 14);
+        checkFrames(vThread1, false, 13);
         LockSupport.unpark(vThread1);
         vThread1.join();
 
diff --git a/test/hotspot/jtreg/serviceability/jvmti/vthread/GetThreadState/GetThreadStateTest.java b/test/hotspot/jtreg/serviceability/jvmti/vthread/GetThreadState/GetThreadStateTest.java
index 4ee1d1a0bfc..cc8f5638c76 100644
--- a/test/hotspot/jtreg/serviceability/jvmti/vthread/GetThreadState/GetThreadStateTest.java
+++ b/test/hotspot/jtreg/serviceability/jvmti/vthread/GetThreadState/GetThreadStateTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,24 +25,29 @@
  * @test id=default
  * @bug 8312498
  * @summary Basic test for JVMTI GetThreadState with virtual threads
+ * @modules java.base/java.lang:+open
  * @library /test/lib
- * @run junit/othervm/native GetThreadStateTest
+ * @run junit/othervm/native --enable-native-access=ALL-UNNAMED GetThreadStateTest
  */
 
 /*
  * @test id=no-vmcontinuations
  * @requires vm.continuations
+ * @modules java.base/java.lang:+open
  * @library /test/lib
- * @run junit/othervm/native -XX:+UnlockExperimentalVMOptions -XX:-VMContinuations GetThreadStateTest
+ * @run junit/othervm/native -XX:+UnlockExperimentalVMOptions -XX:-VMContinuations --enable-native-access=ALL-UNNAMED GetThreadStateTest
  */
 
 import java.util.StringJoiner;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.LockSupport;
 
+import jdk.test.lib.thread.VThreadRunner;
 import jdk.test.lib.thread.VThreadPinner;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import static org.junit.jupiter.api.Assertions.*;
 
 class GetThreadStateTest {
@@ -51,6 +56,11 @@ class GetThreadStateTest {
     static void setup() {
         System.loadLibrary("GetThreadStateTest");
         init();
+
+        // need >=2 carriers for testing pinning when main thread is a virtual thread
+        if (Thread.currentThread().isVirtual()) {
+            VThreadRunner.ensureParallelism(2);
+        }
     }
 
     /**
@@ -105,21 +115,29 @@ void testRunnable() throws Exception {
     }
 
     /**
-     * Test state of thread waiting to enter a monitor.
+     * Test state of thread waiting to enter a monitor when pinned and not pinned.
      */
-    @Test
-    void testMonitorEnter() throws Exception {
-        var started = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testMonitorEnter(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         Object lock = new Object();
         var thread = Thread.ofVirtual().unstarted(() -> {
-            started.set(true);
-            synchronized (lock) { }
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    synchronized (lock) { }
+                });
+            } else {
+                ready.set(true);
+                synchronized (lock) { }
+            }
         });
         try {
             synchronized (lock) {
                 // start thread and wait for it to start execution
                 thread.start();
-                awaitTrue(started);
+                awaitTrue(ready);
 
                 // thread should block on monitor enter
                 int expected = JVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER;
@@ -135,23 +153,31 @@ void testMonitorEnter() throws Exception {
     }
 
     /**
-     * Test state of thread waiting in Object.wait().
+     * Test state of thread waiting in Object.wait() when pinned and not pinned.
      */
-    @Test
-    void testObjectWait() throws Exception {
-        var started = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testObjectWait(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         Object lock = new Object();
         var thread = Thread.ofVirtual().start(() -> {
             synchronized (lock) {
-                started.set(true);
                 try {
-                    lock.wait();
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait();
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait();
+                    }
                 } catch (InterruptedException e) { }
             }
         });
         try {
             // wait for thread to start execution
-            awaitTrue(started);
+            awaitTrue(ready);
 
             // thread should wait
             int expected = JVMTI_THREAD_STATE_ALIVE |
@@ -177,23 +203,33 @@ void testObjectWait() throws Exception {
     }
 
     /**
-     * Test state of thread waiting in Object.wait(millis).
+     * Test state of thread waiting in Object.wait(millis) when pinned and not pinned.
      */
-    @Test
-    void testObjectWaitMillis() throws Exception {
-        var started = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testObjectWaitMillis(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         Object lock = new Object();
         var thread = Thread.ofVirtual().start(() -> {
             synchronized (lock) {
-                started.set(true);
-                try {
-                    lock.wait(Long.MAX_VALUE);
-                } catch (InterruptedException e) { }
+                synchronized (lock) {
+                    try {
+                        if (pinned) {
+                            VThreadPinner.runPinned(() -> {
+                                ready.set(true);
+                                lock.wait(Long.MAX_VALUE);
+                            });
+                        } else {
+                            ready.set(true);
+                            lock.wait(Long.MAX_VALUE);
+                        }
+                    } catch (InterruptedException e) { }
+                }
             }
         });
         try {
             // wait for thread to start execution
-            awaitTrue(started);
+            awaitTrue(ready);
 
             // thread should wait
             int expected = JVMTI_THREAD_STATE_ALIVE |
@@ -219,83 +255,31 @@ void testObjectWaitMillis() throws Exception {
     }
 
     /**
-     * Test state of thread parked with LockSupport.park.
+     * Test state of thread parked with LockSupport.park when pinned and not pinned.
      */
-    @Test
-    void testPark() throws Exception {
-        var started = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testPark(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var done = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
-            started.set(true);
-            while (!done.get()) {
-                LockSupport.park();
-            }
-        });
-        try {
-            // wait for thread to start execution
-            awaitTrue(started);
-
-            // thread should park
-            int expected = JVMTI_THREAD_STATE_ALIVE |
-                    JVMTI_THREAD_STATE_WAITING |
-                    JVMTI_THREAD_STATE_WAITING_INDEFINITELY |
-                    JVMTI_THREAD_STATE_PARKED;
-            await(thread, expected);
-        } finally {
-            done.set(true);
-            LockSupport.unpark(thread);
-            thread.join();
-        }
-    }
-
-    /**
-     * Test state of thread parked with LockSupport.parkNanos.
-     */
-    @Test
-    void testParkNanos() throws Exception {
-        var started = new AtomicBoolean();
-        var done = new AtomicBoolean();
-        var thread = Thread.ofVirtual().start(() -> {
-            started.set(true);
-            while (!done.get()) {
-                LockSupport.parkNanos(Long.MAX_VALUE);
-            }
-        });
-        try {
-            // wait for thread to start execution
-            awaitTrue(started);
-
-            // thread should park
-            int expected = JVMTI_THREAD_STATE_ALIVE |
-                    JVMTI_THREAD_STATE_WAITING |
-                    JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT |
-                    JVMTI_THREAD_STATE_PARKED;
-            await(thread, expected);
-        } finally {
-            done.set(true);
-            LockSupport.unpark(thread);
-            thread.join();
-        }
-    }
-
-    /**
-     * Test state of thread parked with LockSupport.park while holding a monitor.
-     */
-    @Test
-    void testParkWhenPinned() throws Exception {
-        var started = new AtomicBoolean();
-        var done = new AtomicBoolean();
-        var thread = Thread.ofVirtual().start(() -> {
-            VThreadPinner.runPinned(() -> {
-                started.set(true);
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    while (!done.get()) {
+                        LockSupport.park();
+                    }
+                });
+            } else {
+                ready.set(true);
                 while (!done.get()) {
                     LockSupport.park();
                 }
-            });
+            }
         });
         try {
             // wait for thread to start execution
-            awaitTrue(started);
+            awaitTrue(ready);
 
             // thread should park
             int expected = JVMTI_THREAD_STATE_ALIVE |
@@ -311,23 +295,31 @@ void testParkWhenPinned() throws Exception {
     }
 
     /**
-     * Test state of thread parked with LockSupport.parkNanos while holding a monitor.
+     * Test state of thread parked with LockSupport.parkNanos when pinned and not pinned.
      */
-    @Test
-    void testParkNanosWhenPinned() throws Exception {
-        var started = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testParkNanos(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var done = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
-            VThreadPinner.runPinned(() -> {
-                started.set(true);
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    while (!done.get()) {
+                        LockSupport.parkNanos(Long.MAX_VALUE);
+                    }
+                });
+            } else {
+                ready.set(true);
                 while (!done.get()) {
                     LockSupport.parkNanos(Long.MAX_VALUE);
                 }
-            });
+            }
         });
         try {
             // wait for thread to start execution
-            awaitTrue(started);
+            awaitTrue(ready);
 
             // thread should park
             int expected = JVMTI_THREAD_STATE_ALIVE |
diff --git a/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/VThreadEventTest.java b/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/VThreadEventTest.java
index 61b94a4484b..845e9adba01 100644
--- a/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/VThreadEventTest.java
+++ b/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/VThreadEventTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,47 +28,22 @@
  * @requires vm.continuations
  * @requires vm.jvmti
  * @requires vm.compMode != "Xcomp"
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
  * @run main/othervm/native
- *     -Djdk.virtualThreadScheduler.parallelism=9
  *     -Djdk.attach.allowAttachSelf=true -XX:+EnableDynamicAgentLoading VThreadEventTest attach
  */
 
 import com.sun.tools.attach.VirtualMachine;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.LockSupport;
 import java.util.List;
 import java.util.ArrayList;
-
-/*
- * The test uses custom implementation of the CountDownLatch class.
- * The reason is we want the state of tested thread to be predictable.
- * With java.util.concurrent.CountDownLatch it is not clear what thread state is expected.
- */
-class CountDownLatch {
-    private int count = 0;
-
-    CountDownLatch(int count) {
-        this.count = count;
-    }
-
-    public synchronized void countDown() {
-        count--;
-        notify();
-    }
-
-    public synchronized void await() throws InterruptedException {
-        while (count > 0) {
-            wait(1);
-        }
-    }
-}
+import jdk.test.lib.thread.VThreadRunner;
 
 public class VThreadEventTest {
-    static final int TCNT1 = 10;
-    static final int TCNT2 = 4;
-    static final int TCNT3 = 4;
-    static final int THREAD_CNT = TCNT1 + TCNT2 + TCNT3;
+    static final int PARKED_THREAD_COUNT = 4;
+    static final int SPINNING_THREAD_COUNT = 4;
 
     private static void log(String msg) { System.out.println(msg); }
 
@@ -77,128 +52,96 @@ public class VThreadEventTest {
     private static native int threadUnmountCount();
 
     private static volatile boolean attached;
-    private static boolean failed;
-    private static List<Thread> test1Threads = new ArrayList(TCNT1);
-
-    private static CountDownLatch ready0 = new CountDownLatch(THREAD_CNT);
-    private static CountDownLatch ready1 = new CountDownLatch(TCNT1);
-    private static CountDownLatch ready2 = new CountDownLatch(THREAD_CNT);
-    private static CountDownLatch mready = new CountDownLatch(1);
-
-    private static void await(CountDownLatch dumpedLatch) {
-        try {
-            dumpedLatch.await();
-        } catch (InterruptedException e) {
-            throw new RuntimeException(e);
-        }
+
+    // called by agent when it is initialized and has enabled events
+    static void agentStarted() {
+        attached = true;
     }
 
-    // The test1 vthreads are kept unmounted until interrupted after agent attach.
-    static final Runnable test1 = () -> {
-        synchronized (test1Threads) {
-            test1Threads.add(Thread.currentThread());
+    public static void main(String[] args) throws Exception {
+        if (Thread.currentThread().isVirtual()) {
+            System.out.println("Skipping test as current thread is a virtual thread");
+            return;
         }
-        log("test1 vthread started");
-        ready0.countDown();
-        await(mready);
-        ready1.countDown(); // to guaranty state is not State.WAITING after await(mready)
-        try {
-            Thread.sleep(20000); // big timeout to keep unmounted until interrupted
-        } catch (InterruptedException ex) {
-            // it is expected, ignore
+        VThreadRunner.ensureParallelism(SPINNING_THREAD_COUNT+1);
+
+        // start threads that park (unmount)
+        var threads1 = new ArrayList<Thread>();
+        for (int i = 0; i < PARKED_THREAD_COUNT; i++) {
+            var started = new AtomicBoolean();
+            var thread = Thread.startVirtualThread(() -> {
+                started.set(true);
+                LockSupport.park();
+            });
+
+            // wait for thread to start execution + park
+            while (!started.get()) {
+                Thread.sleep(10);
+            }
+            await(thread, Thread.State.WAITING);
+            threads1.add(thread);
         }
-        ready2.countDown();
-    };
-
-    // The test2 vthreads are kept mounted until agent attach.
-    static final Runnable test2 = () -> {
-        log("test2 vthread started");
-        ready0.countDown();
-        await(mready);
-        while (!attached) {
-            // keep mounted
+
+        // start threads that spin (stay mounted)
+        var threads2 = new ArrayList<Thread>();
+        for (int i = 0; i < SPINNING_THREAD_COUNT; i++) {
+            var started = new AtomicBoolean();
+            var thread = Thread.startVirtualThread(() -> {
+                started.set(true);
+                while (!attached) {
+                    Thread.onSpinWait();
+                }
+            });
+
+            // wait for thread to start execution
+            while (!started.get()) {
+                Thread.sleep(10);
+            }
+            threads2.add(thread);
         }
-        ready2.countDown();
-    };
-
-    // The test3 vthreads are kept mounted until agent attach.
-    static final Runnable test3 = () -> {
-        log("test3 vthread started");
-        ready0.countDown();
-        await(mready);
+
+        // attach to the current VM
+        VirtualMachine vm = VirtualMachine.attach(String.valueOf(ProcessHandle.current().pid()));
+        vm.loadAgentLibrary("VThreadEventTest");
+
+        // wait for agent to start
         while (!attached) {
-            // keep mounted
+            Thread.sleep(10);
         }
-        LockSupport.parkNanos(10_000_000L); // will cause extra mount and unmount
-        ready2.countDown();
-    };
 
-    public static void main(String[] args) throws Exception {
-        if (Runtime.getRuntime().availableProcessors() < 8) {
-            log("WARNING: test expects at least 8 processors.");
+        // unpark the threads that were parked
+        for (Thread thread : threads1) {
+            LockSupport.unpark(thread);
         }
-        try (ExecutorService executorService = Executors.newVirtualThreadPerTaskExecutor()) {
-            for (int i = 0; i < TCNT1; i++) {
-                executorService.execute(test1);
-            }
-            for (int i = 0; i < TCNT2; i++) {
-                executorService.execute(test2);
-            }
-            for (int i = 0; i < TCNT3; i++) {
-                executorService.execute(test3);
-            }
-            await(ready0);
-            mready.countDown();
-            await(ready1); // to guarantee state is not State.TIMED_WAITING after await(mready) in test1()
-            // wait for test1 threads to reach TIMED_WAITING state in sleep()
-            for (Thread t : test1Threads) {
-                Thread.State state = t.getState();
-                log("DBG: state: " + state);
-                while (state != Thread.State.TIMED_WAITING) {
-                    Thread.sleep(10);
-                    state = t.getState();
-                    log("DBG: state: " + state);
-                }
-            }
-
-            VirtualMachine vm = VirtualMachine.attach(String.valueOf(ProcessHandle.current().pid()));
-            vm.loadAgentLibrary("VThreadEventTest");
-            Thread.sleep(200); // to allow the agent to get ready
 
-            attached = true;
-            for (Thread t : test1Threads) {
-                 t.interrupt();
-            }
-            ready2.await();
+        // wait for all threads to terminate
+        for (Thread thread : threads1) {
+            thread.join();
         }
-        // wait until all VirtualThreadEnd events have been sent
-        for (int sleepNo = 1; threadEndCount() < THREAD_CNT; sleepNo++) {
-            Thread.sleep(100);
-            if (sleepNo % 100 == 0) { // 10 sec period of waiting
-                log("main: waited seconds: " + sleepNo/10);
-            }
+        for (Thread thread : threads2) {
+            thread.join();
         }
+
         int threadEndCnt = threadEndCount();
         int threadMountCnt = threadMountCount();
         int threadUnmountCnt = threadUnmountCount();
-        int threadEndExp = THREAD_CNT;
-        int threadMountExp = THREAD_CNT - TCNT2;
-        int threadUnmountExp = THREAD_CNT + TCNT3;
 
-        log("ThreadEnd cnt: "     + threadEndCnt     + " (expected: " + threadEndExp + ")");
-        log("ThreadMount cnt: "   + threadMountCnt   + " (expected: " + threadMountExp + ")");
-        log("ThreadUnmount cnt: " + threadUnmountCnt + " (expected: " + threadUnmountExp + ")");
+        int threadCount = PARKED_THREAD_COUNT + SPINNING_THREAD_COUNT;
+        log("VirtualThreadEnd events: " + threadEndCnt + ", expected: " + threadCount);
+        log("VirtualThreadMount events: " + threadMountCnt + ", expected: " + PARKED_THREAD_COUNT);
+        log("VirtualThreadUnmount events: " + threadUnmountCnt + ", expected: " + threadCount);
 
-        if (threadEndCnt != threadEndExp) {
-            log("FAILED: unexpected count of ThreadEnd events");
+        boolean failed = false;
+        if (threadEndCnt != threadCount) {
+            log("FAILED: unexpected count of VirtualThreadEnd events");
             failed = true;
         }
-        if (threadMountCnt != threadMountExp) {
-            log("FAILED: unexpected count of ThreadMount events");
+        if (threadMountCnt != PARKED_THREAD_COUNT) {
+            log("FAILED: unexpected count of VirtualThreadMount events");
             failed = true;
         }
-        if (threadUnmountCnt != threadUnmountExp) {
-            log("FAILED: unexpected count of ThreadUnmount events");
+        if (threadUnmountCnt != threadCount) {
+            log("FAILED: unexpected count of VirtualThreadUnmount events");
             failed = true;
         }
         if (failed) {
@@ -206,5 +149,14 @@ public static void main(String[] args) throws Exception {
         }
     }
 
+    private static void await(Thread thread, Thread.State expectedState) throws InterruptedException {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            assert state != Thread.State.TERMINATED : "Thread has terminated";
+            Thread.sleep(10);
+            state = thread.getState();
+        }
+    }
+
 }
 
diff --git a/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/libVThreadEventTest.cpp b/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/libVThreadEventTest.cpp
index afd06e66b32..c97a8ef3471 100644
--- a/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/libVThreadEventTest.cpp
+++ b/test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadEventTest/libVThreadEventTest.cpp
@@ -65,6 +65,11 @@ Agent_OnAttach(JavaVM *vm, char *options, void *reserved) {
   jvmtiEventCallbacks callbacks;
   jvmtiCapabilities caps;
   jvmtiError err;
+  JNIEnv *env;
+  jsize nVMs;
+  jint res;
+  jclass clazz;
+  jmethodID mid;
 
   LOG("Agent_OnAttach started\n");
   if (vm->GetEnv(reinterpret_cast<void **>(&jvmti), JVMTI_VERSION) != JNI_OK || !jvmti) {
@@ -97,6 +102,41 @@ Agent_OnAttach(JavaVM *vm, char *options, void *reserved) {
   check_jvmti_error(err, "SetEventNotificationMode for VirtualThreadUnmount");
 
   LOG("vthread events enabled\n");
+
+  // call VThreadEventTest.agentStarted to notify test that agent has started
+
+  res = JNI_GetCreatedJavaVMs(&vm, 1, &nVMs);
+  if (res != JNI_OK) {
+      LOG("JNI_GetCreatedJavaVMs failed: %d\n", res);
+      return JNI_ERR;
+  }
+
+  res = vm->GetEnv((void **) &env, JNI_VERSION_21);
+  if (res != JNI_OK) {
+    LOG("GetEnv failed: %d\n", res);
+    return JNI_ERR;
+  }
+
+  clazz = env->FindClass("VThreadEventTest");
+  if (clazz == NULL) {
+      LOG("FindClass failed\n");
+      return JNI_ERR;
+  }
+
+  mid = env->GetStaticMethodID(clazz, "agentStarted", "()V");
+  if (mid == NULL) {
+      LOG("GetStaticMethodID failed\n");
+      return JNI_ERR;
+  }
+
+  env->CallStaticVoidMethod(clazz, mid);
+  if (env->ExceptionOccurred()) {
+      LOG("CallStaticVoidMethod failed\n");
+      return JNI_ERR;
+  }
+
+  LOG("Agent_OnAttach done\n");
+
   return JVMTI_ERROR_NONE;
 }
 
diff --git a/test/jdk/ProblemList.txt b/test/jdk/ProblemList.txt
index 05e42b49330..8e627e27d7a 100644
--- a/test/jdk/ProblemList.txt
+++ b/test/jdk/ProblemList.txt
@@ -606,7 +606,6 @@ sun/security/smartcardio/TestExclusive.java                     8039280 generic-
 sun/security/smartcardio/TestMultiplePresent.java               8039280 generic-all
 sun/security/smartcardio/TestPresent.java                       8039280 generic-all
 sun/security/smartcardio/TestTransmit.java                      8039280 generic-all
-com/sun/crypto/provider/Cipher/DES/PerformanceTest.java         8039280 generic-all
 com/sun/security/auth/callback/TextCallbackHandler/Password.java 8039280 generic-all
 com/sun/security/sasl/gsskerb/AuthOnly.java                     8039280 generic-all
 com/sun/security/sasl/gsskerb/ConfSecurityLayer.java            8039280 generic-all
diff --git a/test/jdk/TEST.groups b/test/jdk/TEST.groups
index 6a5be3736e8..55ae0e9c67b 100644
--- a/test/jdk/TEST.groups
+++ b/test/jdk/TEST.groups
@@ -621,7 +621,6 @@ jdk_core_manual_no_input = \
 
 jdk_security_manual_no_input = \
     :jdk_security_infra \
-    com/sun/crypto/provider/Cipher/DES/PerformanceTest.java \
     com/sun/crypto/provider/Cipher/AEAD/GCMIncrementByte4.java \
     com/sun/crypto/provider/Cipher/AEAD/GCMIncrementDirect4.java \
     com/sun/security/auth/callback/TextCallbackHandler/Password.java \
diff --git a/test/jdk/com/sun/crypto/provider/Cipher/DES/PerformanceTest.java b/test/jdk/com/sun/crypto/provider/Cipher/DES/PerformanceTest.java
index 698acd083b4..33167cafbd9 100644
--- a/test/jdk/com/sun/crypto/provider/Cipher/DES/PerformanceTest.java
+++ b/test/jdk/com/sun/crypto/provider/Cipher/DES/PerformanceTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,11 +26,8 @@
  * @bug 0000000
  * @summary This test checks performance of various ciphers.
  * @author Jan Luehe
- * @run main/manual PerformanceTest
  */
-import java.security.*;
 import java.security.spec.*;
-import java.io.*;
 import javax.crypto.*;
 import javax.crypto.spec.*;
 
@@ -178,14 +175,16 @@ public void runTest(byte[] data, int count) throws Exception {
         long start, end;
         cipher.init(Cipher.ENCRYPT_MODE, cipherKey, params);
 
-        start = System.currentTimeMillis();
+        start = getTimeInMicroseconds();
         for (int i=0; i<count-1; i++) {
             cipher.update(data, 0, data.length);
         }
         cipher.doFinal(data, 0, data.length);
-        end = System.currentTimeMillis();
+        end = getTimeInMicroseconds();
 
-        int speed = (int)((data.length * count)/(end - start));
+        // To avoid dividing by zero in the rare case where end is equal to start
+        long executionTime = end != start ? end - start : 1L;
+        int speed = (int) ((data.length * count) / executionTime);
         sum += speed;
         col.append(speed);
     }
@@ -198,8 +197,12 @@ public void printHeadings() {
         System.out.println
             ("=========================================================");
         System.out.println
-            ("Algorithm                      DataSize Rounds Kbytes/sec");
+            ("Algorithm                      DataSize Rounds Bytes/microsec");
 
     }
 
+    private static long getTimeInMicroseconds() {
+        return System.nanoTime() / 1000;
+    }
+
 }
diff --git a/test/jdk/java/foreign/TestConcurrentClose.java b/test/jdk/java/foreign/TestConcurrentClose.java
index 7f39ef39040..06dc7375cda 100644
--- a/test/jdk/java/foreign/TestConcurrentClose.java
+++ b/test/jdk/java/foreign/TestConcurrentClose.java
@@ -36,6 +36,7 @@
  *   -XX:+UnlockDiagnosticVMOptions
  *   -XX:+WhiteBoxAPI
  *   -XX:CompileCommand=dontinline,TestConcurrentClose$SegmentAccessor::doAccess
+ *   -Xbatch
  *   TestConcurrentClose
  */
 
@@ -71,7 +72,7 @@ public class TestConcurrentClose {
 
     static final int ITERATIONS = 5;
     static final int SEGMENT_SIZE = 10_000;
-    static final int MAX_EXECUTOR_WAIT_SECONDS = 20;
+    static final int MAX_EXECUTOR_WAIT_SECONDS = 60;
     static final int NUM_ACCESSORS = 50;
 
     static final AtomicLong start = new AtomicLong();
@@ -176,13 +177,8 @@ static void start(String name) {
     }
 
     private static void awaitCompilation() throws InterruptedException {
-        int retries = 0;
         while (WB.getMethodCompilationLevel(DO_ACCESS_METHOD, false) != C2_COMPILED_LEVEL) {
-            if (retries > 20) {
-                throw new IllegalStateException("SegmentAccessor::doAccess method not being compiled");
-            }
             Thread.sleep(1000);
-            retries++;
         }
     }
 }
diff --git a/test/jdk/java/lang/Process/WaitForDuration.java b/test/jdk/java/lang/Process/WaitForDuration.java
index d9172b305a0..76c69e36d13 100644
--- a/test/jdk/java/lang/Process/WaitForDuration.java
+++ b/test/jdk/java/lang/Process/WaitForDuration.java
@@ -55,9 +55,14 @@ static Stream<Arguments> durations() {
     @MethodSource("durations")
     void testEdgeDurations(Duration d, int sleepMillis, boolean expected)
             throws IOException, InterruptedException {
-        var pb = ProcessTools.createTestJavaProcessBuilder(
-            WaitForDuration.class.getSimpleName(), Integer.toString(sleepMillis));
-        assertEquals(expected, pb.start().waitFor(d));
+        var child = ProcessTools.createTestJavaProcessBuilder(
+            WaitForDuration.class.getSimpleName(), Integer.toString(sleepMillis))
+                .start();
+        try {
+            assertEquals(expected, child.waitFor(d));
+        } finally {
+            child.destroy();
+        }
     }
 
     @Test
diff --git a/test/jdk/java/lang/Thread/virtual/CarrierThreadInfo.java b/test/jdk/java/lang/Thread/virtual/CarrierThreadInfo.java
new file mode 100644
index 00000000000..75ef0376a7e
--- /dev/null
+++ b/test/jdk/java/lang/Thread/virtual/CarrierThreadInfo.java
@@ -0,0 +1,243 @@
+/*
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test id=default
+ * @bug 8284161 8286788
+ * @summary Test java.lang.management.ThreadInfo contains expected information for carrier threads
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run junit CarrierThreadInfo
+ */
+
+/**
+ * @test id=LM_LIGHTWEIGHT
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run junit/othervm -XX:LockingMode=2 CarrierThreadInfo
+ */
+
+/**
+ * @test id=LM_LEGACY
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run junit/othervm -XX:LockingMode=1 CarrierThreadInfo
+ */
+
+/**
+ * @test id=LM_MONITOR
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run junit/othervm -XX:LockingMode=0 CarrierThreadInfo
+ */
+
+import java.lang.management.LockInfo;
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+import java.util.Arrays;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import jdk.test.lib.thread.VThreadScheduler;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class CarrierThreadInfo {
+
+    /**
+     * Test that ThreadInfo.getLockedMonitors returns information about a lock held by
+     * a carrier thread.
+     */
+    @Test
+    void testCarrierThreadHoldsLock() throws Exception {
+        Object lock = new Object();
+        ThreadFactory factory = task -> Thread.ofPlatform().unstarted(() -> {
+            synchronized (lock) {
+                task.run();
+            }
+        });
+
+        try (var scheduler = new CustomScheduler(factory)) {
+            var started = new AtomicBoolean();
+            var done = new AtomicBoolean();
+            Thread vthread = scheduler.forkVirtualThread(() -> {
+                started.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
+                }
+            });
+            try {
+                awaitTrue(started);
+
+                // carrier threads holds the lock
+                long carrierId = scheduler.carrier().threadId();
+                ThreadInfo threadInfo = ManagementFactory.getPlatformMXBean(ThreadMXBean.class)
+                        .getThreadInfo(new long[] { carrierId }, true, true)[0];
+                boolean holdsLock = Arrays.stream(threadInfo.getLockedMonitors())
+                        .anyMatch(mi -> mi.getIdentityHashCode() == System.identityHashCode(lock));
+                assertTrue(holdsLock, "Carrier should hold lock");
+
+            } finally {
+                done.set(true);
+            }
+        }
+    }
+
+    /**
+     * Test that ThreadInfo.getLockedMonitors does not return information about a lock
+     * held by mounted virtual thread.
+     */
+    @Test
+    void testVirtualThreadHoldsLock() throws Exception {
+        ThreadFactory factory = Executors.defaultThreadFactory();
+        try (var scheduler = new CustomScheduler(factory)) {
+            var started = new AtomicBoolean();
+            var lock = new Object();
+            var done = new AtomicBoolean();
+            Thread vthread = scheduler.forkVirtualThread(() -> {
+                started.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
+                }
+            });
+            try {
+                awaitTrue(started);
+
+                // carrier threads does not hold lock
+                long carrierId = scheduler.carrier().threadId();
+                ThreadInfo threadInfo = ManagementFactory.getPlatformMXBean(ThreadMXBean.class)
+                        .getThreadInfo(new long[] { carrierId }, true, true)[0];
+                boolean holdsLock = Arrays.stream(threadInfo.getLockedMonitors())
+                        .anyMatch(mi -> mi.getIdentityHashCode() == System.identityHashCode(lock));
+                assertFalse(holdsLock, "Carrier should not hold lock");
+
+            } finally {
+                done.set(true);
+            }
+        }
+    }
+
+    /**
+     * Test that ThreadInfo.getLockOwnerId and getLockInfo return information about a
+     * synthetic lock that make it appear that the carrier is blocking waiting on the
+     * virtual thread.
+     */
+    @Test
+    void testCarrierThreadWaits() throws Exception {
+        ThreadFactory factory = Executors.defaultThreadFactory();
+        try (var scheduler = new CustomScheduler(factory)) {
+            var started = new AtomicBoolean();
+            var done = new AtomicBoolean();
+            Thread vthread = scheduler.forkVirtualThread(() -> {
+                started.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
+                }
+            });
+            try {
+                awaitTrue(started);
+
+                long carrierId = scheduler.carrier().threadId();
+                long vthreadId = vthread.threadId();
+
+                ThreadInfo threadInfo = ManagementFactory.getThreadMXBean().getThreadInfo(carrierId);
+                assertNotNull(threadInfo);
+
+                // carrier should be blocked waiting for lock owned by virtual thread
+                assertEquals(vthreadId, threadInfo.getLockOwnerId());
+
+                // carrier thread should be on blocked waiting on virtual thread
+                LockInfo lockInfo = threadInfo.getLockInfo();
+                assertNotNull(lockInfo);
+                assertEquals(vthread.getClass().getName(), lockInfo.getClassName());
+                assertEquals(System.identityHashCode(vthread), lockInfo.getIdentityHashCode());
+
+            } finally {
+                done.set(true);
+            }
+        }
+    }
+
+    /**
+     * Custom scheduler with a single carrier thread.
+     */
+    private static class CustomScheduler implements AutoCloseable {
+        private final ExecutorService pool;
+        private final Executor scheduler;
+        private final AtomicReference<Thread> carrierRef = new AtomicReference<>();
+
+        CustomScheduler(ThreadFactory factory) {
+            pool = Executors.newSingleThreadExecutor(factory);
+            scheduler = task -> {
+                pool.submit(() -> {
+                    carrierRef.set(Thread.currentThread());
+                    try {
+                        task.run();
+                    } finally {
+                        carrierRef.set(null);
+                    }
+                });
+            };
+        }
+
+        /**
+         * Returns the carrier thread if a virtual thread is mounted.
+         */
+        Thread carrier() throws InterruptedException {
+            return carrierRef.get();
+        }
+
+        /**
+         * Starts a virtual thread to execute the give task.
+         */
+        Thread forkVirtualThread(Runnable task) {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+            Thread thread = factory.newThread(task);
+            thread.start();
+            return thread;
+        }
+
+        @Override
+        public void close() {
+            pool.close();
+        }
+    }
+
+    /**
+     * Waits for the boolean value to become true.
+     */
+    private static void awaitTrue(AtomicBoolean ref) throws InterruptedException {
+        while (!ref.get()) {
+            Thread.sleep(20);
+        }
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/CarrierThreadWaits.java b/test/jdk/java/lang/Thread/virtual/CarrierThreadWaits.java
deleted file mode 100644
index d1d5e72204f..00000000000
--- a/test/jdk/java/lang/Thread/virtual/CarrierThreadWaits.java
+++ /dev/null
@@ -1,110 +0,0 @@
-/*
- * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/**
- * @test
- * @bug 8284161 8286788
- * @summary Test that a carrier thread waits on a virtual thread
- * @requires vm.continuations
- * @modules java.base/java.lang:+open
- * @run junit CarrierThreadWaits
- */
-
-/**
- * @test
- * @requires vm.continuations & vm.debug
- * @modules java.base/java.lang:+open
- * @run junit/othervm -XX:LockingMode=0 CarrierThreadWaits
- */
-
-import java.lang.management.LockInfo;
-import java.lang.management.ManagementFactory;
-import java.lang.management.ThreadInfo;
-import java.util.concurrent.Executor;
-import java.util.concurrent.ForkJoinPool;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
-
-import org.junit.jupiter.api.Test;
-import static org.junit.jupiter.api.Assertions.*;
-
-class CarrierThreadWaits {
-
-    @Test
-    void testCarrierThreadWaiting() throws Exception {
-        try (ForkJoinPool pool = new ForkJoinPool(1)) {
-            var carrierRef = new AtomicReference<Thread>();
-            var vthreadRef = new AtomicReference<Thread>();
-
-            Executor scheduler = task -> {
-                pool.submit(() -> {
-                    Thread carrier = Thread.currentThread();
-                    carrierRef.set(carrier);
-                    Thread vthread = vthreadRef.get();
-
-                    System.err.format("%s run task (%s) ...%n", carrier, vthread);
-                    task.run();
-                    System.err.format("%s task done (%s)%n", carrier, vthread);
-                });
-            };
-
-            // start a virtual thread that spins and remains mounted until "done"
-            var started = new AtomicBoolean();
-            var done = new AtomicBoolean();
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            Thread vthread = builder.unstarted(() -> {
-                started.set(true);
-                while (!done.get()) {
-                    Thread.onSpinWait();
-                }
-            });
-            vthreadRef.set(vthread);
-            vthread.start();
-
-            try {
-                // wait for virtual thread to start
-                while (!started.get()) {
-                    Thread.sleep(10);
-                }
-
-                Thread carrier = carrierRef.get();
-
-                long carrierId = carrier.threadId();
-                long vthreadId = vthread.threadId();
-
-                // carrier thread should be on WAITING on virtual thread
-                ThreadInfo ti = ManagementFactory.getThreadMXBean().getThreadInfo(carrierId);
-                Thread.State state = ti.getThreadState();
-                LockInfo lockInfo = ti.getLockInfo();
-                assertEquals(Thread.State.WAITING, state);
-                assertNotNull(lockInfo);
-                assertEquals(vthread.getClass().getName(), lockInfo.getClassName());
-                assertEquals(System.identityHashCode(vthread), lockInfo.getIdentityHashCode());
-                assertEquals(vthreadId, ti.getLockOwnerId());
-            } finally {
-                done.set(true);
-            }
-        }
-    }
-
-}
diff --git a/test/jdk/java/lang/Thread/virtual/CustomScheduler.java b/test/jdk/java/lang/Thread/virtual/CustomScheduler.java
index 5bde81905ec..4289add0a3a 100644
--- a/test/jdk/java/lang/Thread/virtual/CustomScheduler.java
+++ b/test/jdk/java/lang/Thread/virtual/CustomScheduler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,7 @@
  * @summary Test virtual threads using a custom scheduler
  * @requires vm.continuations
  * @modules java.base/java.lang:+open
+ * @library /test/lib
  * @run junit CustomScheduler
  */
 
@@ -35,9 +36,12 @@
 import java.util.List;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.LockSupport;
 
+import jdk.test.lib.thread.VThreadScheduler;
+import jdk.test.lib.thread.VThreadRunner;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.AfterAll;
@@ -65,10 +69,13 @@ static void shutdown() {
      */
     @Test
     void testCustomScheduler1() throws Exception {
-        AtomicReference<Executor> ref = new AtomicReference<>();
-        ThreadBuilders.virtualThreadBuilder(scheduler1).start(() -> {
-            ref.set(scheduler(Thread.currentThread()));
-        }).join();
+        var ref = new AtomicReference<Executor>();
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler1);
+        Thread thread = factory.newThread(() -> {
+            ref.set(VThreadScheduler.scheduler(Thread.currentThread()));
+        });
+        thread.start();
+        thread.join();
         assertTrue(ref.get() == scheduler1);
     }
 
@@ -77,17 +84,7 @@ void testCustomScheduler1() throws Exception {
      */
     @Test
     void testCustomScheduler2() throws Exception {
-        AtomicReference<Executor> ref = new AtomicReference<>();
-        Thread.ofVirtual().start(() -> {
-            try {
-                ThreadBuilders.virtualThreadBuilder(scheduler1).start(() -> {
-                    ref.set(scheduler(Thread.currentThread()));
-                }).join();
-            } catch (Exception e) {
-                e.printStackTrace();
-            }
-        }).join();
-        assertTrue(ref.get() == scheduler1);
+        VThreadRunner.run(this::testCustomScheduler1);
     }
 
     /**
@@ -96,16 +93,19 @@ void testCustomScheduler2() throws Exception {
      */
     @Test
     void testCustomScheduler3() throws Exception {
-        AtomicReference<Executor> ref = new AtomicReference<>();
-        ThreadBuilders.virtualThreadBuilder(scheduler1).start(() -> {
+        var ref = new AtomicReference<Executor>();
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler1);
+        Thread thread = factory.newThread(() -> {
             try {
                 Thread.ofVirtual().start(() -> {
-                    ref.set(scheduler(Thread.currentThread()));
+                    ref.set(VThreadScheduler.scheduler(Thread.currentThread()));
                 }).join();
             } catch (Exception e) {
                 e.printStackTrace();
             }
-        }).join();
+        });
+        thread.start();
+        thread.join();
         assertTrue(ref.get() == scheduler1);
     }
 
@@ -115,16 +115,22 @@ void testCustomScheduler3() throws Exception {
      */
     @Test
     void testCustomScheduler4() throws Exception {
-        AtomicReference<Executor> ref = new AtomicReference<>();
-        ThreadBuilders.virtualThreadBuilder(scheduler1).start(() -> {
+        var ref = new AtomicReference<Executor>();
+        ThreadFactory factory1 = VThreadScheduler.virtualThreadFactory(scheduler1);
+        ThreadFactory factory2 = VThreadScheduler.virtualThreadFactory(scheduler2);
+        Thread thread1 = factory1.newThread(() -> {
             try {
-                ThreadBuilders.virtualThreadBuilder(scheduler2).start(() -> {
-                    ref.set(scheduler(Thread.currentThread()));
-                }).join();
+                Thread thread2 = factory2.newThread(() -> {
+                    ref.set(VThreadScheduler.scheduler(Thread.currentThread()));
+                });
+                thread2.start();
+                thread2.join();
             } catch (Exception e) {
                 e.printStackTrace();
             }
-        }).join();
+        });
+        thread1.start();
+        thread1.join();
         assertTrue(ref.get() == scheduler2);
     }
 
@@ -149,8 +155,9 @@ void testBadCarrier() {
             }
             assertTrue(exc.get() instanceof WrongThreadException);
         };
-
-        ThreadBuilders.virtualThreadBuilder(scheduler).start(LockSupport::park);
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+        Thread thread = factory.newThread(LockSupport::park);
+        thread.start();
     }
 
     /**
@@ -162,11 +169,12 @@ void testParkWithInterruptSet() {
         Thread carrier = Thread.currentThread();
         assumeFalse(carrier.isVirtual(), "Main thread is a virtual thread");
         try {
-            var builder = ThreadBuilders.virtualThreadBuilder(Runnable::run);
-            Thread vthread = builder.start(() -> {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(Runnable::run);
+            Thread vthread = factory.newThread(() -> {
                 Thread.currentThread().interrupt();
                 Thread.yield();
             });
+            vthread.start();
             assertTrue(vthread.isInterrupted());
             assertFalse(carrier.isInterrupted());
         } finally {
@@ -183,10 +191,11 @@ void testTerminateWithInterruptSet() {
         Thread carrier = Thread.currentThread();
         assumeFalse(carrier.isVirtual(), "Main thread is a virtual thread");
         try {
-            var builder = ThreadBuilders.virtualThreadBuilder(Runnable::run);
-            Thread vthread = builder.start(() -> {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(Runnable::run);
+            Thread vthread = factory.newThread(() -> {
                 Thread.currentThread().interrupt();
             });
+            vthread.start();
             assertTrue(vthread.isInterrupted());
             assertFalse(carrier.isInterrupted());
         } finally {
@@ -204,11 +213,13 @@ void testRunWithInterruptSet() throws Exception {
             Thread.currentThread().interrupt();
             task.run();
         };
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
         try {
             AtomicBoolean interrupted = new AtomicBoolean();
-            Thread vthread = ThreadBuilders.virtualThreadBuilder(scheduler).start(() -> {
+            Thread vthread = factory.newThread(() -> {
                 interrupted.set(Thread.currentThread().isInterrupted());
             });
+            vthread.start();
             assertFalse(vthread.isInterrupted());
         } finally {
             Thread.interrupted();
@@ -216,18 +227,60 @@ void testRunWithInterruptSet() throws Exception {
     }
 
     /**
-     * Returns the scheduler for the given virtual thread.
+     * Test custom scheduler throwing OOME when starting a thread.
      */
-    private static Executor scheduler(Thread thread) {
-        if (!thread.isVirtual())
-            throw new IllegalArgumentException("Not a virtual thread");
-        try {
-            Field scheduler = Class.forName("java.lang.VirtualThread")
-                    .getDeclaredField("scheduler");
-            scheduler.setAccessible(true);
-            return (Executor) scheduler.get(thread);
-        } catch (Exception e) {
-            throw new RuntimeException(e);
+    @Test
+    void testThreadStartOOME() throws Exception {
+        Executor scheduler = task -> {
+            System.err.println("OutOfMemoryError");
+            throw new OutOfMemoryError();
+        };
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+        Thread thread = factory.newThread(() -> { });
+        assertThrows(OutOfMemoryError.class, thread::start);
+    }
+
+    /**
+     * Test custom scheduler throwing OOME when unparking a thread.
+     */
+    @Test
+    void testThreadUnparkOOME() throws Exception {
+        try (ExecutorService executor = Executors.newFixedThreadPool(1)) {
+            AtomicInteger counter = new AtomicInteger();
+            Executor scheduler = task -> {
+                switch (counter.getAndIncrement()) {
+                    case 0 -> executor.execute(task);             // Thread.start
+                    case 1, 2 -> {                                // unpark attempt 1+2
+                        System.err.println("OutOfMemoryError");
+                        throw new OutOfMemoryError();
+                    }
+                    default -> executor.execute(task);
+                }
+                executor.execute(task);
+            };
+
+            // start thread and wait for it to park
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+            var thread = factory.newThread(LockSupport::park);
+            thread.start();
+            await(thread, Thread.State.WAITING);
+
+            // unpark thread, this should retry until OOME is not thrown
+            LockSupport.unpark(thread);
+            thread.join();
+        }
+
+    }
+
+    /**
+     * Waits for the given thread to reach a given state.
+     */
+    private void await(Thread thread, Thread.State expectedState) throws InterruptedException {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            assertTrue(state != Thread.State.TERMINATED, "Thread has terminated");
+            Thread.sleep(10);
+            state = thread.getState();
         }
     }
 }
diff --git a/test/jdk/java/lang/Thread/virtual/GetStackTrace.java b/test/jdk/java/lang/Thread/virtual/GetStackTrace.java
deleted file mode 100644
index 86d5cf7319c..00000000000
--- a/test/jdk/java/lang/Thread/virtual/GetStackTrace.java
+++ /dev/null
@@ -1,129 +0,0 @@
-/*
- * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/**
- * @test
- * @summary Test Thread.getStackTrace to examine the stack trace of a virtual
- *     thread and its carrier
- * @requires vm.continuations
- * @modules java.base/java.lang:+open
- * @run main GetStackTrace
- */
-
-import java.util.Objects;
-import java.util.concurrent.BlockingQueue;
-import java.util.concurrent.Executor;
-import java.util.concurrent.LinkedTransferQueue;
-import java.util.stream.Stream;
-
-public class GetStackTrace {
-
-    private static final Object LOCK = new Object();
-
-    public static void main(String[] args) throws Exception {
-        try (var scheduler = new Scheduler()) {
-            Thread vthread = scheduler.startVirtualThread(() -> {
-                synchronized (LOCK) {
-                    try {
-                        LOCK.wait();
-                    } catch (InterruptedException e) { }
-                }
-            });
-
-            try {
-                // wait for virtual thread to wait
-                while (vthread.getState() != Thread.State.WAITING) {
-                    Thread.sleep(10);
-                }
-
-                // bottom-most frame of virtual thread should be VirtualThread.run
-                System.out.println(vthread);
-                StackTraceElement[] vthreadStack = vthread.getStackTrace();
-                Stream.of(vthreadStack).forEach(System.out::println);
-                assertEquals("run", vthreadStack[vthreadStack.length - 1].getMethodName());
-
-                System.out.println();
-
-                // top-most frame of carrier thread should be Continuation.run
-                // bottom-most frame of carrier thread should be Thread.run
-                var carrier = scheduler.thread();
-                System.out.println(carrier);
-                StackTraceElement[] carrierStack = carrier.getStackTrace();
-                Stream.of(carrierStack).forEach(System.out::println);
-                assertEquals("run", carrierStack[0].getMethodName());
-                assertEquals("run", carrierStack[carrierStack.length - 1].getMethodName());
-            } finally {
-                vthread.interrupt();
-            }
-        }
-    }
-
-    /**
-     * A scheduler with one thread.
-     */
-    private static class Scheduler implements AutoCloseable, Executor {
-        private final BlockingQueue<Runnable> tasks = new LinkedTransferQueue<>();
-        private final Thread thread;
-        private volatile boolean done;
-
-        Scheduler() {
-            this.thread = Thread.ofPlatform().start(() -> {
-                try {
-                    while (!done) {
-                        Runnable task = tasks.take();
-                        task.run();
-                    }
-                } catch (InterruptedException e) { }
-            });
-        }
-
-        Thread thread() {
-            return thread;
-        }
-
-        @Override
-        public void close() throws InterruptedException {
-            done = true;
-            thread.interrupt();
-            thread.join();
-        }
-
-        @Override
-        public void execute(Runnable task) {
-            tasks.add(task);
-        }
-
-        Thread startVirtualThread(Runnable task) {
-            return ThreadBuilders.virtualThreadBuilder(this).start(task);
-        }
-    }
-
-    private static void assertTrue(boolean e) {
-        if (!e) throw new RuntimeException();
-    }
-
-    private static void assertEquals(Object x, Object y) {
-        if (!Objects.equals(x, y))
-            throw new RuntimeException();
-    }
-}
diff --git a/test/jdk/java/lang/Thread/virtual/GetStackTraceWhenRunnable.java b/test/jdk/java/lang/Thread/virtual/GetStackTraceWhenRunnable.java
deleted file mode 100644
index 38760eb52a8..00000000000
--- a/test/jdk/java/lang/Thread/virtual/GetStackTraceWhenRunnable.java
+++ /dev/null
@@ -1,85 +0,0 @@
-/*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/**
- * @test
- * @summary Test Thread::getStackTrace on a virtual thread that is runnable-unmounted
- * @requires vm.continuations
- * @run main/othervm -Djdk.virtualThreadScheduler.maxPoolSize=1 GetStackTraceWhenRunnable
- */
-
-import java.io.IOException;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.locks.LockSupport;
-
-public class GetStackTraceWhenRunnable {
-
-    public static void main(String[] args) throws Exception {
-
-        // start thread1 and wait for it to park
-        Thread thread1 = Thread.startVirtualThread(LockSupport::park);
-        while (thread1.getState() != Thread.State.WAITING) {
-            Thread.sleep(20);
-        }
-
-        // start thread2 to pin the carrier thread
-        var started = new AtomicBoolean();
-        var done = new AtomicBoolean();
-        Thread thread2 = Thread.startVirtualThread(() -> {
-            started.set(true);
-            while (!done.get()) {
-                Thread.onSpinWait();
-            }
-        });
-        try {
-            // wait for thread2 to start
-            while (!started.get()) {
-                Thread.sleep(10);
-            }
-
-            // unpark thread1 and check that it is "stuck" in the runnable state
-            // (the carrier thread is pinned, no other virtual thread can run)
-            LockSupport.unpark(thread1);
-            for (int i = 0; i < 5; i++) {
-                assertTrue(thread1.getState() == Thread.State.RUNNABLE);
-                Thread.sleep(100);
-            }
-
-            // print thread1's stack trace
-            StackTraceElement[] stack = thread1.getStackTrace();
-            assertTrue(stack.length > 0);
-            for (StackTraceElement e : stack) {
-                System.out.println(e);
-            }
-        } finally {
-            done.set(true);
-            thread2.join();
-            thread1.join();
-        }
-    }
-
-    static void assertTrue(boolean e) {
-        if (!e) throw new RuntimeException();
-    }
-}
diff --git a/test/jdk/java/lang/Thread/virtual/JfrEvents.java b/test/jdk/java/lang/Thread/virtual/JfrEvents.java
index 282a8959fe8..539ac2104ed 100644
--- a/test/jdk/java/lang/Thread/virtual/JfrEvents.java
+++ b/test/jdk/java/lang/Thread/virtual/JfrEvents.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,9 +40,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.LockSupport;
-import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -52,15 +50,25 @@
 import jdk.jfr.consumer.RecordingFile;
 
 import jdk.test.lib.thread.VThreadPinner;
-import jdk.test.lib.thread.VThreadRunner.ThrowingRunnable;
+import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadScheduler;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
-import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 import static org.junit.jupiter.api.Assertions.*;
 
 class JfrEvents {
 
+    @BeforeAll
+    static void setup() {
+        int minParallelism = 2;
+        if (Thread.currentThread().isVirtual()) {
+            minParallelism++;
+        }
+        VThreadRunner.ensureParallelism(minParallelism);
+    }
+
     /**
      * Test jdk.VirtualThreadStart and jdk.VirtualThreadEnd events.
      */
@@ -93,100 +101,42 @@ void testVirtualThreadStartAndEnd() throws Exception {
     }
 
     /**
-     * Arguments for testVirtualThreadPinned to test jdk.VirtualThreadPinned event.
-     *   [0] label/description
-     *   [1] the operation to park/wait
-     *   [2] the Thread.State when parked/waiting
-     *   [3] the action to unpark/notify the thread
-     */
-    static Stream<Arguments> pinnedCases() {
-        Object lock = new Object();
-
-        // park with native frame on stack
-        var finish1 = new AtomicBoolean();
-        var parkWhenPinned = Arguments.of(
-            "LockSupport.park when pinned",
-            (ThrowingRunnable<Exception>) () -> {
-                VThreadPinner.runPinned(() -> {
-                    while (!finish1.get()) {
-                        LockSupport.park();
-                    }
-                });
-            },
-            Thread.State.WAITING,
-                (Consumer<Thread>) t -> {
-                    finish1.set(true);
-                    LockSupport.unpark(t);
-                }
-        );
-
-        // timed park with native frame on stack
-        var finish2 = new AtomicBoolean();
-        var timedParkWhenPinned = Arguments.of(
-            "LockSupport.parkNanos when pinned",
-            (ThrowingRunnable<Exception>) () -> {
-                VThreadPinner.runPinned(() -> {
-                    while (!finish2.get()) {
-                        LockSupport.parkNanos(Long.MAX_VALUE);
-                    }
-                });
-            },
-            Thread.State.TIMED_WAITING,
-            (Consumer<Thread>) t -> {
-                finish2.set(true);
-                LockSupport.unpark(t);
-            }
-        );
-
-        return Stream.of(parkWhenPinned, timedParkWhenPinned);
-    }
-
-    /**
-     * Test jdk.VirtualThreadPinned event.
+     * Test jdk.VirtualThreadPinned event when parking while pinned.
      */
     @ParameterizedTest
-    @MethodSource("pinnedCases")
-    void testVirtualThreadPinned(String label,
-                                 ThrowingRunnable<Exception> parker,
-                                 Thread.State expectedState,
-                                 Consumer<Thread> unparker) throws Exception {
-
+    @ValueSource(booleans = { true, false })
+    void testParkWhenPinned(boolean timed) throws Exception {
         try (Recording recording = new Recording()) {
             recording.enable("jdk.VirtualThreadPinned");
-
             recording.start();
-            try {
-                var exception = new AtomicReference<Throwable>();
-                var thread = Thread.ofVirtual().start(() -> {
-                    try {
-                        parker.run();
-                    } catch (Throwable e) {
-                        exception.set(e);
+
+            var started = new AtomicBoolean();
+            var done = new AtomicBoolean();
+            var vthread = Thread.startVirtualThread(() -> {
+                VThreadPinner.runPinned(() -> {
+                    started.set(true);
+                    while (!done.get()) {
+                        if (timed) {
+                            LockSupport.parkNanos(Long.MAX_VALUE);
+                        } else {
+                            LockSupport.park();
+                        }
                     }
                 });
-                try {
-                    // wait for thread to park/wait
-                    Thread.State state = thread.getState();
-                    while (state != expectedState) {
-                        assertTrue(state != Thread.State.TERMINATED, thread.toString());
-                        Thread.sleep(10);
-                        state = thread.getState();
-                    }
-                } finally {
-                    unparker.accept(thread);
-                    thread.join();
-                    assertNull(exception.get());
-                }
+            });
+
+            try {
+                // wait for thread to start and park
+                awaitTrue(started);
+                await(vthread, timed ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
             } finally {
+                done.set(true);
+                LockSupport.unpark(vthread);
+                vthread.join();
                 recording.stop();
             }
 
-            Map<String, Integer> events = sumEvents(recording);
-            System.err.println(events);
-
-            // should have at least one pinned event
-            int pinnedCount = events.getOrDefault("jdk.VirtualThreadPinned", 0);
-            assertTrue(pinnedCount >= 1, "Expected one or more events");
+            assertContainsPinnedEvent(recording, vthread);
         }
     }
 
@@ -203,16 +153,14 @@ void testVirtualThreadSubmitFailed() throws Exception {
                 Executor scheduler = task -> pool.execute(task);
 
                 // create virtual thread that uses custom scheduler
-                ThreadFactory factory = ThreadBuilders.virtualThreadBuilder(scheduler).factory();
+                ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
 
                 // start a thread
                 Thread thread = factory.newThread(LockSupport::park);
                 thread.start();
 
                 // wait for thread to park
-                while (thread.getState() != Thread.State.WAITING) {
-                    Thread.sleep(10);
-                }
+                await(thread, Thread.State.WAITING);
 
                 // shutdown scheduler
                 pool.shutdown();
@@ -232,14 +180,23 @@ void testVirtualThreadSubmitFailed() throws Exception {
                 recording.stop();
             }
 
-            Map<String, Integer> events = sumEvents(recording);
-            System.err.println(events);
-
-            int count = events.getOrDefault("jdk.VirtualThreadSubmitFailed", 0);
-            assertEquals(2, count);
+            List<RecordedEvent> submitFailedEvents = find(recording, "jdk.VirtualThreadSubmitFailed");
+            System.err.println(submitFailedEvents);
+            assertTrue(submitFailedEvents.size() == 2, "Expected two events");
         }
     }
 
+    /**
+     * Returns the list of events in the given recording with the given name.
+     */
+    private static List<RecordedEvent> find(Recording recording, String name) throws IOException {
+        Path recordingFile = recordingFile(recording);
+        return RecordingFile.readAllEvents(recordingFile)
+                .stream()
+                .filter(e -> e.getEventType().getName().equals(name))
+                .toList();
+    }
+
     /**
      * Read the events from the recording and return a map of event name to count.
      */
@@ -264,4 +221,38 @@ private static Path recordingFile(Recording recording) throws IOException {
         }
         return recordingFile;
     }
+
+    /**
+     * Assert that a recording contains a jdk.VirtualThreadPinned event on the given thread.
+     */
+    private void assertContainsPinnedEvent(Recording recording, Thread thread) throws IOException {
+        List<RecordedEvent> pinnedEvents = find(recording, "jdk.VirtualThreadPinned");
+        assertTrue(pinnedEvents.size() > 0, "No jdk.VirtualThreadPinned events in recording");
+        System.err.println(pinnedEvents);
+
+        long tid = thread.threadId();
+        assertTrue(pinnedEvents.stream()
+                        .anyMatch(e -> e.getThread().getJavaThreadId() == tid),
+                "jdk.VirtualThreadPinned for javaThreadId = " + tid + " not found");
+    }
+
+    /**
+     * Waits for the given boolean to be set to true.
+     */
+    private void awaitTrue(AtomicBoolean b) throws InterruptedException {
+        while (!b.get()) {
+            Thread.sleep(10);
+        }
+    }
+
+    /**
+     * Waits for the given thread to reach a given state.
+     */
+    private static void await(Thread thread, Thread.State expectedState) throws InterruptedException {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            Thread.sleep(10);
+            state = thread.getState();
+        }
+    }
 }
diff --git a/test/jdk/java/lang/Thread/virtual/MonitorEnterExit.java b/test/jdk/java/lang/Thread/virtual/MonitorEnterExit.java
new file mode 100644
index 00000000000..d1f2bf0c1bf
--- /dev/null
+++ b/test/jdk/java/lang/Thread/virtual/MonitorEnterExit.java
@@ -0,0 +1,410 @@
+/*
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test id=default
+ * @summary Test virtual thread with monitor enter/exit
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run junit/othervm --enable-native-access=ALL-UNNAMED MonitorEnterExit
+ */
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.LockSupport;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import jdk.test.lib.thread.VThreadPinner;
+import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadScheduler;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.RepeatedTest;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.api.condition.*;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assumptions.*;
+
+class MonitorEnterExit {
+    static final int MAX_ENTER_DEPTH = 256;
+
+    @BeforeAll
+    static void setup() {
+        // need >=2 carriers for testing pinning when main thread is a virtual thread
+        if (Thread.currentThread().isVirtual()) {
+            VThreadRunner.ensureParallelism(2);
+        }
+    }
+
+    /**
+     * Test monitor enter with no contention.
+     */
+    @Test
+    void testEnterNoContention() throws Exception {
+        var lock = new Object();
+        VThreadRunner.run(() -> {
+            synchronized (lock) {
+                assertTrue(Thread.holdsLock(lock));
+            }
+            assertFalse(Thread.holdsLock(lock));
+        });
+    }
+
+    /**
+     * Test monitor enter with contention, monitor is held by platform thread.
+     */
+    @Test
+    void testEnterWhenHeldByPlatformThread() throws Exception {
+        testEnterWithContention();
+    }
+
+    /**
+     * Test monitor enter with contention, monitor is held by virtual thread.
+     */
+    @Test
+    void testEnterWhenHeldByVirtualThread() throws Exception {
+        VThreadRunner.run(this::testEnterWithContention);
+    }
+
+    /**
+     * Test monitor enter with contention, monitor will be held by caller thread.
+     */
+    private void testEnterWithContention() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var entered = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().unstarted(() -> {
+            started.countDown();
+            synchronized (lock) {
+                assertTrue(Thread.holdsLock(lock));
+                entered.set(true);
+            }
+            assertFalse(Thread.holdsLock(lock));
+        });
+        try {
+            synchronized (lock) {
+                vthread.start();
+
+                // wait for thread to start and block
+                started.await();
+                await(vthread, Thread.State.BLOCKED);
+
+                assertFalse(entered.get());
+            }
+        } finally {
+            vthread.join();
+        }
+        assertTrue(entered.get());
+    }
+
+    /**
+     * Test monitor reenter.
+     */
+    @Test
+    void testReenter() throws Exception {
+        var lock = new Object();
+        VThreadRunner.run(() -> {
+            testReenter(lock, 0);
+            assertFalse(Thread.holdsLock(lock));
+        });
+    }
+
+    private void testReenter(Object lock, int depth) {
+        if (depth < MAX_ENTER_DEPTH) {
+            synchronized (lock) {
+                assertTrue(Thread.holdsLock(lock));
+                testReenter(lock, depth + 1);
+                assertTrue(Thread.holdsLock(lock));
+            }
+        }
+    }
+
+    /**
+     * Test monitor enter when pinned.
+     */
+    @Test
+    void testEnterWhenPinned() throws Exception {
+        var lock = new Object();
+        VThreadPinner.runPinned(() -> {
+            synchronized (lock) {
+                assertTrue(Thread.holdsLock(lock));
+            }
+            assertFalse(Thread.holdsLock(lock));
+        });
+    }
+
+    /**
+     * Test monitor reenter when pinned.
+     */
+    @Test
+    void testReenterWhenPinned() throws Exception {
+        VThreadRunner.run(() -> {
+            var lock = new Object();
+            synchronized (lock) {
+                VThreadPinner.runPinned(() -> {
+                    assertTrue(Thread.holdsLock(lock));
+                    synchronized (lock) {
+                        assertTrue(Thread.holdsLock(lock));
+                    }
+                    assertTrue(Thread.holdsLock(lock));
+                });
+            }
+            assertFalse(Thread.holdsLock(lock));
+        });
+    }
+
+    /**
+     * Test contended monitor enter when pinned. Monitor is held by platform thread.
+     */
+    @Test
+    void testContendedEnterWhenPinnedHeldByPlatformThread() throws Exception {
+        testEnterWithContentionWhenPinned();
+    }
+
+    /**
+     * Test contended monitor enter when pinned. Monitor is held by virtual thread.
+     */
+    @Test
+    void testContendedEnterWhenPinnedHeldByVirtualThread() throws Exception {
+        // need at least two carrier threads
+        int previousParallelism = VThreadRunner.ensureParallelism(2);
+        try {
+            VThreadRunner.run(this::testEnterWithContentionWhenPinned);
+        } finally {
+            VThreadRunner.setParallelism(previousParallelism);
+        }
+    }
+
+    /**
+     * Test contended monitor enter when pinned, monitor will be held by caller thread.
+     */
+    private void testEnterWithContentionWhenPinned() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var entered = new AtomicBoolean();
+        Thread vthread = Thread.ofVirtual().unstarted(() -> {
+            VThreadPinner.runPinned(() -> {
+                started.countDown();
+                synchronized (lock) {
+                    entered.set(true);
+                }
+            });
+        });
+        synchronized (lock) {
+            // start thread and wait for it to block
+            vthread.start();
+            started.await();
+            await(vthread, Thread.State.BLOCKED);
+            assertFalse(entered.get());
+        }
+        vthread.join();
+
+        // check thread entered monitor
+        assertTrue(entered.get());
+    }
+
+    /**
+     * Returns a stream of elements that are ordered pairs of platform and virtual thread
+     * counts. 0,2,4,..16 platform threads. 2,4,6,..32 virtual threads.
+     */
+    static Stream<Arguments> threadCounts() {
+        return IntStream.range(0, 17)
+                .filter(i -> i % 2 == 0)
+                .mapToObj(i -> i)
+                .flatMap(np -> IntStream.range(2, 33)
+                        .filter(i -> i % 2 == 0)
+                        .mapToObj(vp -> Arguments.of(np, vp)));
+    }
+
+    /**
+     * Test mutual exclusion of monitors with platform and virtual threads.
+     */
+    @ParameterizedTest
+    @MethodSource("threadCounts")
+    void testMutualExclusion(int nPlatformThreads, int nVirtualThreads) throws Exception {
+        class Counter {
+            int count;
+            synchronized void increment() {
+                count++;
+                Thread.yield();
+            }
+        }
+        var counter = new Counter();
+        int nThreads = nPlatformThreads + nVirtualThreads;
+        var threads = new Thread[nThreads];
+        int index = 0;
+        for (int i = 0; i < nPlatformThreads; i++) {
+            threads[index] = Thread.ofPlatform()
+                    .name("platform-" + index)
+                    .unstarted(counter::increment);
+            index++;
+        }
+        for (int i = 0; i < nVirtualThreads; i++) {
+            threads[index] = Thread.ofVirtual()
+                    .name("virtual-" + index)
+                    .unstarted(counter::increment);
+            index++;
+        }
+        // start all threads
+        for (Thread thread : threads) {
+            thread.start();
+        }
+        // wait for all threads to terminate
+        for (Thread thread : threads) {
+            thread.join();
+        }
+        assertEquals(nThreads, counter.count);
+    }
+
+    /**
+     * Test unblocking a virtual thread waiting to enter a monitor held by a platform thread.
+     */
+    @RepeatedTest(20)
+    void testUnblockingByPlatformThread() throws Exception {
+        testUnblocking();
+    }
+
+    /**
+     * Test unblocking a virtual thread waiting to enter a monitor held by another
+     * virtual thread.
+     */
+    @RepeatedTest(20)
+    void testUnblockingByVirtualThread() throws Exception {
+        VThreadRunner.run(this::testUnblocking);
+    }
+
+    /**
+     * Test unblocking a virtual thread waiting to enter a monitor, monitor will be
+     * initially be held by caller thread.
+     */
+    private void testUnblocking() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var entered = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().unstarted(() -> {
+            started.countDown();
+            synchronized (lock) {
+                entered.set(true);
+            }
+        });
+        try {
+            synchronized (lock) {
+                vthread.start();
+                started.await();
+
+                // random delay before exiting monitor
+                switch (ThreadLocalRandom.current().nextInt(4)) {
+                    case 0 -> { /* no delay */}
+                    case 1 -> Thread.onSpinWait();
+                    case 2 -> Thread.yield();
+                    case 3 -> await(vthread, Thread.State.BLOCKED);
+                    default -> fail();
+                }
+
+                assertFalse(entered.get());
+            }
+        } finally {
+            vthread.join();
+        }
+        assertTrue(entered.get());
+    }
+
+    /**
+     * Test that unblocking a virtual thread waiting to enter a monitor does not consume
+     * the thread's parking permit.
+     */
+    @Test
+    void testParkingPermitNotConsumed() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var vthread = Thread.ofVirtual().unstarted(() -> {
+            started.countDown();
+            LockSupport.unpark(Thread.currentThread());
+            synchronized (lock) { }  // should block
+            LockSupport.park();      // should not park
+        });
+
+        synchronized (lock) {
+            vthread.start();
+            // wait for thread to start and block
+            started.await();
+            await(vthread, Thread.State.BLOCKED);
+        }
+        vthread.join();
+    }
+
+    /**
+     * Test that unblocking a virtual thread waiting to enter a monitor does not make
+     * available the thread's parking permit.
+     */
+    @Test
+    void testParkingPermitNotOffered() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var vthread = Thread.ofVirtual().unstarted(() -> {
+            started.countDown();
+            synchronized (lock) { }  // should block
+            LockSupport.park();      // should park
+        });
+
+        synchronized (lock) {
+            vthread.start();
+            // wait for thread to start and block
+            started.await();
+            await(vthread, Thread.State.BLOCKED);
+        }
+
+        try {
+            // wait for thread to park, it should not terminate
+            await(vthread, Thread.State.WAITING);
+            vthread.join(Duration.ofMillis(100));
+            assertEquals(Thread.State.WAITING, vthread.getState());
+        } finally {
+            LockSupport.unpark(vthread);
+            vthread.join();
+        }
+    }
+
+    /**
+     * Waits for the given thread to reach a given state.
+     */
+    private void await(Thread thread, Thread.State expectedState) throws InterruptedException {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            assertTrue(state != Thread.State.TERMINATED, "Thread has terminated");
+            Thread.sleep(10);
+            state = thread.getState();
+        }
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/MonitorWaitNotify.java b/test/jdk/java/lang/Thread/virtual/MonitorWaitNotify.java
index 1320cc8f15f..5f730dbbf0a 100644
--- a/test/jdk/java/lang/Thread/virtual/MonitorWaitNotify.java
+++ b/test/jdk/java/lang/Thread/virtual/MonitorWaitNotify.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -21,41 +21,78 @@
  * questions.
  */
 
-/**
- * @test
+/*
+ * @test id=default
  * @summary Test virtual threads using Object.wait/notifyAll
  * @modules java.base/java.lang:+open
  * @library /test/lib
- * @run junit MonitorWaitNotify
+ * @run junit/othervm --enable-native-access=ALL-UNNAMED MonitorWaitNotify
  */
 
-import java.util.concurrent.Semaphore;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.LockSupport;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+import java.util.stream.Collectors;
 
+import jdk.test.lib.thread.VThreadScheduler;
+import jdk.test.lib.thread.VThreadRunner;
 import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadPinner;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assumptions.*;
 
 class MonitorWaitNotify {
 
+    @BeforeAll
+    static void setup() {
+        // need >=2 carriers for testing pinning
+        VThreadRunner.ensureParallelism(2);
+    }
+
     /**
      * Test virtual thread waits, notified by platform thread.
      */
-    @Test
-    void testWaitNotify1() throws Exception {
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testWaitNotify1(boolean pinned) throws Exception {
         var lock = new Object();
-        var ready = new Semaphore(0);
+        var ready = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
             synchronized (lock) {
-                ready.release();
                 try {
-                    lock.wait();
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait();
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait();
+                    }
                 } catch (InterruptedException e) { }
             }
         });
-        // thread invokes notify
-        ready.acquire();
+        awaitTrue(ready);
+
+        // notify, thread should block waiting to reenter
         synchronized (lock) {
             lock.notifyAll();
+            await(thread, Thread.State.BLOCKED);
         }
         thread.join();
     }
@@ -66,15 +103,13 @@ void testWaitNotify1() throws Exception {
     @Test
     void testWaitNotify2() throws Exception {
         var lock = new Object();
-        var ready = new Semaphore(0);
-        var thread = Thread.ofVirtual().start(() -> {
-            ready.acquireUninterruptibly();
+        var thread = Thread.ofVirtual().unstarted(() -> {
             synchronized (lock) {
                 lock.notifyAll();
             }
         });
         synchronized (lock) {
-            ready.release();
+            thread.start();
             lock.wait();
         }
         thread.join();
@@ -83,89 +118,447 @@ void testWaitNotify2() throws Exception {
     /**
      * Test virtual thread waits, notified by another virtual thread.
      */
-    @Test
-    void testWaitNotify3() throws Exception {
-        // need at least two carrier threads due to pinning
-        int previousParallelism = VThreadRunner.ensureParallelism(2);
-        try {
-            var lock = new Object();
-            var ready = new Semaphore(0);
-            var thread1 = Thread.ofVirtual().start(() -> {
-                synchronized (lock) {
-                    ready.release();
-                    try {
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testWaitNotify3(boolean pinned) throws Exception {
+        var lock = new Object();
+        var ready = new AtomicBoolean();
+        var thread1 = Thread.ofVirtual().start(() -> {
+            synchronized (lock) {
+                try {
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait();
+                        });
+                    } else {
+                        ready.set(true);
                         lock.wait();
-                    } catch (InterruptedException e) { }
+                    }
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
                 }
-            });
-            var thread2 = Thread.ofVirtual().start(() -> {
-                ready.acquireUninterruptibly();
+            }
+        });
+        var thread2 = Thread.ofVirtual().start(() -> {
+            try {
+                awaitTrue(ready);
+
+                // notify, thread should block waiting to reenter
                 synchronized (lock) {
                     lock.notifyAll();
+                    await(thread1, Thread.State.BLOCKED);
                 }
-            });
-            thread1.join();
-            thread2.join();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+        thread1.join();
+        thread2.join();
+    }
+
+    /**
+     * Test notifyAll when there are no threads waiting.
+     */
+    @ParameterizedTest
+    @ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
+    void testNotifyBeforeWait(int timeout) throws Exception {
+        var lock = new Object();
+
+        // no threads waiting
+        synchronized (lock) {
+            lock.notifyAll();
+        }
+
+        var ready = new AtomicBoolean();
+        var thread = Thread.ofVirtual().start(() -> {
+            try {
+                synchronized (lock) {
+                    ready.set(true);
+
+                    // thread should wait
+                    if (timeout > 0) {
+                        lock.wait(timeout);
+                    } else {
+                        lock.wait();
+                    }
+                }
+            } catch (InterruptedException e) { }
+        });
+
+        try {
+            // wait for thread to start and wait
+            awaitTrue(ready);
+            Thread.State expectedState = timeout > 0
+                    ? Thread.State.TIMED_WAITING
+                    : Thread.State.WAITING;
+            await(thread, expectedState);
+
+            // poll thread state again, it should still be waiting
+            Thread.sleep(10);
+            assertEquals(thread.getState(), expectedState);
         } finally {
-            // restore
-            VThreadRunner.setParallelism(previousParallelism);
+            synchronized (lock) {
+                lock.notifyAll();
+            }
+            thread.join();
         }
     }
+    /**
+     * Test duration of timed Object.wait.
+     */
+    @Test
+    void testTimedWaitDuration1() throws Exception {
+        var lock = new Object();
+
+        var durationRef = new AtomicReference<Long>();
+        var thread = Thread.ofVirtual().start(() -> {
+            try {
+                synchronized (lock) {
+                    long start = millisTime();
+                    lock.wait(2000);
+                    durationRef.set(millisTime() - start);
+                }
+            } catch (InterruptedException e) { }
+        });
+
+        thread.join();
+
+        long duration = durationRef.get();
+        checkDuration(duration, 1900, 20_000);
+    }
 
     /**
-     * Test interrupt status set when calling Object.wait.
+     * Test duration of timed Object.wait. This test invokes wait twice, first with a short
+     * timeout, the second with a longer timeout. The test scenario ensures that the
+     * timeout from the first wait doesn't interfere with the second wait.
      */
     @Test
-    void testWaitNotify4() throws Exception {
+    void testTimedWaitDuration2() throws Exception {
+        var lock = new Object();
+
+        var ready = new AtomicBoolean();
+        var waited = new AtomicBoolean();
+        var durationRef = new AtomicReference<Long>();
+        var thread = Thread.ofVirtual().start(() -> {
+            try {
+                synchronized (lock) {
+                    ready.set(true);
+                    lock.wait(200);
+                    waited.set(true);
+
+                    long start = millisTime();
+                    lock.wait(2000);
+                    durationRef.set(millisTime() - start);
+                }
+            } catch (InterruptedException e) { }
+        });
+
+        awaitTrue(ready);
+        synchronized (lock) {
+            // wake thread if waiting in first wait
+            if (!waited.get()) {
+                lock.notifyAll();
+            }
+        }
+
+        thread.join();
+
+        long duration = durationRef.get();
+        checkDuration(duration, 1900, 20_000);
+    }
+
+    /**
+     * Testing invoking Object.wait with interrupt status set.
+     */
+    @ParameterizedTest
+    @ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
+    void testWaitWithInterruptSet(int timeout) throws Exception {
         VThreadRunner.run(() -> {
-            Thread t = Thread.currentThread();
-            t.interrupt();
             Object lock = new Object();
+            synchronized (lock) {
+                Thread.currentThread().interrupt();
+                if (timeout > 0) {
+                    assertThrows(InterruptedException.class, () -> lock.wait(timeout));
+                } else {
+                    assertThrows(InterruptedException.class, lock::wait);
+                }
+                assertFalse(Thread.currentThread().isInterrupted());
+            }
+        });
+    }
+
+    /**
+     * Test interrupting a virtual thread waiting in Object.wait.
+     */
+    @ParameterizedTest
+    @ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
+    void testInterruptWait(int timeout) throws Exception {
+        var lock = new Object();
+        var ready = new AtomicBoolean();
+        var interruptedException = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().start(() -> {
+            synchronized (lock) {
+                try {
+                    ready.set(true);
+                    if (timeout > 0) {
+                        lock.wait(timeout);
+                    } else {
+                        lock.wait();
+                    }
+                } catch (InterruptedException e) {
+                    // check stack trace has the expected frames
+                    Set<String> expected = Set.of("wait0", "wait", "run");
+                    Set<String> methods = Stream.of(e.getStackTrace())
+                            .map(StackTraceElement::getMethodName)
+                            .collect(Collectors.toSet());
+                    assertTrue(methods.containsAll(expected));
+
+                    interruptedException.set(true);
+                }
+            }
+        });
+
+        // wait for thread to start and wait
+        awaitTrue(ready);
+        await(vthread, timeout > 0 ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
+
+        // interrupt thread, should block, then throw InterruptedException
+        synchronized (lock) {
+            vthread.interrupt();
+            await(vthread, Thread.State.BLOCKED);
+        }
+        vthread.join();
+        assertTrue(interruptedException.get());
+    }
+
+    /**
+     * Test interrupting a virtual thread blocked waiting to reenter after waiting.
+     */
+    @ParameterizedTest
+    @ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
+    void testInterruptReenterAfterWait(int timeout) throws Exception {
+        var lock = new Object();
+        var ready = new AtomicBoolean();
+        var interruptedException = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().start(() -> {
+            synchronized (lock) {
+                try {
+                    ready.set(true);
+                    if (timeout > 0) {
+                        lock.wait(timeout);
+                    } else {
+                        lock.wait();
+                    }
+                } catch (InterruptedException e) {
+                    interruptedException.set(true);
+                }
+            }
+        });
+
+        // wait for thread to start and wait
+        awaitTrue(ready);
+        await(vthread, timeout > 0 ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
+
+        // notify, thread should block waiting to reenter
+        synchronized (lock) {
+            lock.notifyAll();
+            await(vthread, Thread.State.BLOCKED);
+
+            // interrupt when blocked
+            vthread.interrupt();
+        }
+
+        vthread.join();
+        assertFalse(interruptedException.get());
+        assertTrue(vthread.isInterrupted());
+    }
+
+    /**
+     * Test Object.wait when the monitor entry count > 1.
+     */
+    @ParameterizedTest
+    @ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
+    void testWaitWhenEnteredManyTimes(int timeout) throws Exception {
+        var lock = new Object();
+        var ready = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().start(() -> {
+            synchronized (lock) {
+                synchronized (lock) {
+                    synchronized (lock) {
+                        try {
+                            ready.set(true);
+                            if (timeout > 0) {
+                                lock.wait(timeout);
+                            } else {
+                                lock.wait();
+                            }
+                        } catch (InterruptedException e) { }
+                    }
+                }
+            }
+        });
+
+        // wait for thread to start and wait
+        awaitTrue(ready);
+        await(vthread, timeout > 0 ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
+
+        // notify, thread should block waiting to reenter
+        synchronized (lock) {
+            lock.notifyAll();
+            await(vthread, Thread.State.BLOCKED);
+        }
+        vthread.join();
+    }
+
+    /**
+     * Test that Object.wait does not consume the thread's parking permit.
+     */
+    @Test
+    void testParkingPermitNotConsumed() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var completed = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().start(() -> {
+            started.countDown();
+            LockSupport.unpark(Thread.currentThread());
             synchronized (lock) {
                 try {
                     lock.wait();
-                    fail();
                 } catch (InterruptedException e) {
-                    // interrupt status should be cleared
-                    assertFalse(t.isInterrupted());
+                    fail("wait interrupted");
                 }
             }
+            LockSupport.park();      // should not park
+            completed.set(true);
         });
+
+        // wait for thread to start and wait
+        started.await();
+        await(vthread, Thread.State.WAITING);
+
+        // wakeup thread
+        synchronized (lock) {
+            lock.notifyAll();
+        }
+
+        // thread should terminate
+        vthread.join();
+        assertTrue(completed.get());
     }
 
     /**
-     * Test interrupt when blocked in Object.wait.
+     * Test that Object.wait does not make available the thread's parking permit.
      */
     @Test
-    void testWaitNotify5() throws Exception {
-        VThreadRunner.run(() -> {
-            Thread t = Thread.currentThread();
-            scheduleInterrupt(t, 1000);
-            Object lock = new Object();
+    void testParkingPermitNotOffered() throws Exception {
+        var lock = new Object();
+        var started = new CountDownLatch(1);
+        var readyToPark = new CountDownLatch(1);
+        var completed = new AtomicBoolean();
+        var vthread = Thread.ofVirtual().start(() -> {
+            started.countDown();
             synchronized (lock) {
                 try {
                     lock.wait();
-                    fail();
                 } catch (InterruptedException e) {
-                    // interrupt status should be cleared
-                    assertFalse(t.isInterrupted());
+                    fail("wait interrupted");
                 }
             }
+            readyToPark.countDown();
+            LockSupport.park();      // should park
+            completed.set(true);
         });
+
+        // wait for thread to start and wait
+        started.await();
+        await(vthread, Thread.State.WAITING);
+
+        // wakeup thread
+        synchronized (lock) {
+            lock.notifyAll();
+        }
+
+        // thread should park
+        readyToPark.await();
+        await(vthread, Thread.State.WAITING);
+
+        LockSupport.unpark(vthread);
+
+        // thread should terminate
+        vthread.join();
+        assertTrue(completed.get());
     }
 
     /**
-     * Schedule a thread to be interrupted after a delay.
+     * Test that wait(long) throws IAE when timeout is negative.
      */
-    private static void scheduleInterrupt(Thread thread, long delay) {
-        Runnable interruptTask = () -> {
-            try {
-                Thread.sleep(delay);
-                thread.interrupt();
-            } catch (Exception e) {
-                e.printStackTrace();
+    @Test
+    void testIllegalArgumentException() throws Exception {
+        VThreadRunner.run(() -> {
+            Object obj = new Object();
+            synchronized (obj) {
+                assertThrows(IllegalArgumentException.class, () -> obj.wait(-1L));
+                assertThrows(IllegalArgumentException.class, () -> obj.wait(-1000L));
+                assertThrows(IllegalArgumentException.class, () -> obj.wait(Long.MIN_VALUE));
             }
-        };
-        new Thread(interruptTask).start();
+        });
+    }
+
+    /**
+     * Test that wait throws IMSE when not owner.
+     */
+    @Test
+    void testIllegalMonitorStateException() throws Exception {
+        VThreadRunner.run(() -> {
+            Object obj = new Object();
+            assertThrows(IllegalMonitorStateException.class, () -> obj.wait());
+            assertThrows(IllegalMonitorStateException.class, () -> obj.wait(0));
+            assertThrows(IllegalMonitorStateException.class, () -> obj.wait(1000));
+            assertThrows(IllegalMonitorStateException.class, () -> obj.wait(Long.MAX_VALUE));
+        });
+    }
+
+    /**
+     * Waits for the boolean value to become true.
+     */
+    private static void awaitTrue(AtomicBoolean ref) throws InterruptedException {
+        while (!ref.get()) {
+            Thread.sleep(20);
+        }
+    }
+
+    /**
+     * Waits for the given thread to reach a given state.
+     */
+    private void await(Thread thread, Thread.State expectedState) throws InterruptedException {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            assertTrue(state != Thread.State.TERMINATED, "Thread has terminated");
+            Thread.sleep(10);
+            state = thread.getState();
+        }
+    }
+
+    /**
+     * Returns the current time in milliseconds.
+     */
+    private static long millisTime() {
+        long now = System.nanoTime();
+        return TimeUnit.MILLISECONDS.convert(now, TimeUnit.NANOSECONDS);
+    }
+
+    /**
+     * Check a duration is within expected bounds.
+     * @param duration, in milliseconds
+     * @param min minimum expected duration, in milliseconds
+     * @param max maximum expected duration, in milliseconds
+     * @return the duration (now - start), in milliseconds
+     */
+    private static void checkDuration(long duration, long min, long max) {
+        assertTrue(duration >= min,
+                "Duration " + duration + "ms, expected >= " + min + "ms");
+        assertTrue(duration <= max,
+                "Duration " + duration + "ms, expected <= " + max + "ms");
     }
 }
diff --git a/test/jdk/java/lang/Thread/virtual/ParkWithFixedThreadPool.java b/test/jdk/java/lang/Thread/virtual/ParkWithFixedThreadPool.java
index 950f036458d..28a32fc504a 100644
--- a/test/jdk/java/lang/Thread/virtual/ParkWithFixedThreadPool.java
+++ b/test/jdk/java/lang/Thread/virtual/ParkWithFixedThreadPool.java
@@ -26,12 +26,14 @@
  * @summary Test virtual thread park when scheduler is a fixed thread pool
  * @requires vm.continuations
  * @modules java.base/java.lang:+open
+ * @library /test/lib
  * @run main ParkWithFixedThreadPool
  */
 
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.*;
 import java.util.concurrent.locks.LockSupport;
+import jdk.test.lib.thread.VThreadScheduler;
 
 public class ParkWithFixedThreadPool {
     public static void main(String[] args) throws Exception {
@@ -58,9 +60,7 @@ public void run() {
                 }
             };
 
-            ThreadFactory factory = ThreadBuilders.virtualThreadBuilder(scheduler)
-                    .name("vthread-", 0)
-                    .factory();
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
 
             for (int i = 0; i < vthreadCount; i++) {
                 vthreads[i] = factory.newThread(target);
diff --git a/test/jdk/java/lang/Thread/virtual/Reflection.java b/test/jdk/java/lang/Thread/virtual/Reflection.java
index 4dd34e6c726..f508b7949ff 100644
--- a/test/jdk/java/lang/Thread/virtual/Reflection.java
+++ b/test/jdk/java/lang/Thread/virtual/Reflection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,6 +38,7 @@
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.locks.LockSupport;
 
+import jdk.test.lib.thread.VThreadScheduler;
 import jdk.test.lib.thread.VThreadRunner;
 import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
@@ -142,11 +143,10 @@ static void foo() { }
      */
     @Test
     void testInvokeStatic6() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         Method parkMethod = Parker.class.getDeclaredMethod("park");
         try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            ThreadFactory factory = builder.factory();
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
 
             var ready = new CountDownLatch(1);
             Thread vthread = factory.newThread(() -> {
@@ -321,11 +321,10 @@ static void foo() { }
      */
     @Test
     void testNewInstance6() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         Constructor<?> ctor = Parker.class.getDeclaredConstructor();
         try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            ThreadFactory factory = builder.factory();
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
 
             var ready = new CountDownLatch(1);
             Thread vthread = factory.newThread(() -> {
diff --git a/test/jdk/java/lang/Thread/virtual/StackFrames.java b/test/jdk/java/lang/Thread/virtual/StackFrames.java
new file mode 100644
index 00000000000..6ae65d031dd
--- /dev/null
+++ b/test/jdk/java/lang/Thread/virtual/StackFrames.java
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @summary Test stack traces in exceptions, stack frames walked by the StackWalker,
+ *    and the stack trace returned by Thread.getStackTrace
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open java.management
+ * @library /test/lib
+ * @run junit StackFrames
+ * @run junit/othervm -XX:+UnlockDiagnosticVMOptions -XX:+ShowCarrierFrames StackFrames
+ */
+
+import java.lang.management.ManagementFactory;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.ForkJoinWorkerThread;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Stream;
+import static java.lang.StackWalker.Option.*;
+
+import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadScheduler;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class StackFrames {
+
+    /**
+     * Test that the stack trace in exceptions does not include the carrier thread
+     * frames, except when running with -XX:+ShowCarrierFrames.
+     */
+    @Test
+    void testStackTraceException() throws Exception {
+        VThreadRunner.run(() -> {
+            Exception e = new Exception();
+            boolean found = Arrays.stream(e.getStackTrace())
+                    .map(StackTraceElement::getClassName)
+                    .anyMatch("java.util.concurrent.ForkJoinPool"::equals);
+            assertTrue(found == hasJvmArgument("-XX:+ShowCarrierFrames"));
+        });
+    }
+
+    /**
+     * Test that StackWalker does not include carrier thread frames in the stream of
+     * stack frames.
+     */
+    @Test
+    void testStackWalker() throws Exception {
+        VThreadRunner.run(() -> {
+            StackWalker walker = StackWalker.getInstance(Set.of(RETAIN_CLASS_REFERENCE));
+            boolean found = walker.walk(sf ->
+                    sf.map(StackWalker.StackFrame::getDeclaringClass)
+                            .anyMatch(c -> c == ForkJoinPool.class));
+            assertFalse(found);
+        });
+    }
+
+    /**
+     * Test Thread.getStackTrace returns the expected bottom frame for both the carrier
+     * and virtual thread.
+     */
+    @Test
+    void testBottomFrames() throws Exception {
+        try (ForkJoinPool pool = new ForkJoinPool(1)) {
+            var carrierRef = new AtomicReference<Thread>();
+            Executor scheduler = task -> {
+                pool.submit(() -> {
+                    carrierRef.set(Thread.currentThread());
+                    task.run();
+                });
+            };
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+
+            var ready = new AtomicBoolean();
+            var done = new AtomicBoolean();
+
+            // create virtual thread to use custom scheduler
+            var vthread = factory.newThread(() -> {
+                ready.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
+                }
+            });
+
+            vthread.start();
+            try {
+                awaitTrue(ready);
+
+                // get carrier Thread
+                Thread carrier = carrierRef.get();
+                assertTrue(carrier instanceof ForkJoinWorkerThread);
+
+                // bottom-most frame of virtual thread should be VirtualThread.run
+                System.err.println(vthread);
+                StackTraceElement[] vthreadStack = vthread.getStackTrace();
+                Stream.of(vthreadStack).forEach(e -> System.err.println("    " + e));
+                StackTraceElement bottomFrame = vthreadStack[vthreadStack.length - 1];
+                assertEquals("java.lang.VirtualThread.run",
+                        bottomFrame.getClassName() + "." + bottomFrame.getMethodName());
+
+                // bottom-most frame of carrier thread should be Thread.run
+                System.err.println(carrier);
+                StackTraceElement[] carrierStack = carrier.getStackTrace();
+                Stream.of(carrierStack).forEach(e -> System.err.println("    " + e));
+                bottomFrame = carrierStack[carrierStack.length - 1];
+                assertEquals("java.util.concurrent.ForkJoinWorkerThread.run",
+                        bottomFrame.getClassName() + "." + bottomFrame.getMethodName());
+
+            } finally {
+                done.set(true);
+                vthread.join();
+            }
+        }
+    }
+
+    /**
+     * Returns true if started with the given VM option.
+     */
+    private static boolean hasJvmArgument(String arg) {
+        for (String argument : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
+            if (argument.equals(arg)) return true;
+        }
+        return false;
+    }
+
+    /**
+     * Waits for the boolean value to become true.
+     */
+    private static void awaitTrue(AtomicBoolean ref) throws InterruptedException {
+        while (!ref.get()) {
+            Thread.sleep(20);
+        }
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/StackTraces.java b/test/jdk/java/lang/Thread/virtual/StackTraces.java
deleted file mode 100644
index cb1877090fe..00000000000
--- a/test/jdk/java/lang/Thread/virtual/StackTraces.java
+++ /dev/null
@@ -1,82 +0,0 @@
-/*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/**
- * @test
- * @summary Test stack traces in exceptions and stack frames walked by the StackWalker
- *     API do not include the carrier stack frames
- * @requires vm.continuations
- * @modules java.management
- * @library /test/lib
- * @run junit StackTraces
- * @run junit/othervm -XX:+UnlockDiagnosticVMOptions -XX:+ShowCarrierFrames StackTraces
- */
-
-import java.lang.management.ManagementFactory;
-import java.util.Arrays;
-import java.util.Set;
-import java.util.concurrent.ForkJoinPool;
-import static java.lang.StackWalker.Option.*;
-
-import jdk.test.lib.thread.VThreadRunner;
-import org.junit.jupiter.api.Test;
-import static org.junit.jupiter.api.Assertions.*;
-
-class StackTraces {
-
-    /**
-     * Test that the stack trace in exceptions does not include the carrier thread
-     * frames, except when running with -XX:+ShowCarrierFrames.
-     */
-    @Test
-    void testStackTrace() throws Exception {
-        VThreadRunner.run(() -> {
-            Exception e = new Exception();
-            boolean found = Arrays.stream(e.getStackTrace())
-                    .map(StackTraceElement::getClassName)
-                    .anyMatch("java.util.concurrent.ForkJoinPool"::equals);
-            assertTrue(found == hasJvmArgument("-XX:+ShowCarrierFrames"));
-        });
-    }
-
-    /**
-     * Test that StackWalker does not include carrier thread frames.
-     */
-    @Test
-    void testStackWalker() throws Exception {
-        VThreadRunner.run(() -> {
-            StackWalker walker = StackWalker.getInstance(Set.of(RETAIN_CLASS_REFERENCE));
-            boolean found = walker.walk(sf ->
-                    sf.map(StackWalker.StackFrame::getDeclaringClass)
-                            .anyMatch(c -> c == ForkJoinPool.class));
-            assertFalse(found);
-        });
-    }
-
-    private static boolean hasJvmArgument(String arg) {
-        for (String argument : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
-            if (argument.equals(arg)) return true;
-        }
-        return false;
-    }
-}
diff --git a/test/jdk/java/lang/Thread/virtual/ThreadAPI.java b/test/jdk/java/lang/Thread/virtual/ThreadAPI.java
index b1ccb21910a..3bb5c75a1b5 100644
--- a/test/jdk/java/lang/Thread/virtual/ThreadAPI.java
+++ b/test/jdk/java/lang/Thread/virtual/ThreadAPI.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -61,13 +61,16 @@
 import java.util.stream.Stream;
 import java.nio.channels.Selector;
 
-import jdk.test.lib.thread.VThreadRunner;
 import jdk.test.lib.thread.VThreadPinner;
+import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadScheduler;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 import static org.junit.jupiter.api.Assertions.*;
 import static org.junit.jupiter.api.Assumptions.*;
 
@@ -78,9 +81,12 @@ class ThreadAPI {
     private static ScheduledExecutorService scheduler;
 
     @BeforeAll
-    static void setup() throws Exception {
+    static void setup() {
         ThreadFactory factory = Executors.defaultThreadFactory();
         scheduler = Executors.newSingleThreadScheduledExecutor(factory);
+
+        // need >=2 carriers for testing pinning
+        VThreadRunner.ensureParallelism(2);
     }
 
     @AfterAll
@@ -719,14 +725,7 @@ void testJoin33() throws Exception {
      */
     @Test
     void testJoin34() throws Exception {
-        // need at least two carrier threads due to pinning
-        int previousParallelism = VThreadRunner.ensureParallelism(2);
-        try {
-            VThreadRunner.run(this::testJoin33);
-        } finally {
-            // restore
-            VThreadRunner.setParallelism(previousParallelism);
-        }
+        VThreadRunner.run(this::testJoin33);
     }
 
     /**
@@ -1084,11 +1083,10 @@ void testSetDaemon2() throws Exception {
      */
     @Test
     void testYield1() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         var list = new CopyOnWriteArrayList<String>();
         try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            ThreadFactory factory = builder.factory();
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
             var thread = factory.newThread(() -> {
                 list.add("A");
                 var child = factory.newThread(() -> {
@@ -1112,11 +1110,10 @@ void testYield1() throws Exception {
      */
     @Test
     void testYield2() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         var list = new CopyOnWriteArrayList<String>();
         try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            ThreadFactory factory = builder.factory();
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
             var thread = factory.newThread(() -> {
                 list.add("A");
                 var child = factory.newThread(() -> {
@@ -1708,50 +1705,59 @@ void testGetState3() throws Exception {
      */
     @Test
     void testGetState4() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         AtomicBoolean completed = new AtomicBoolean();
         try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            Thread t1 = builder.start(() -> {
-                Thread t2 = builder.unstarted(LockSupport::park);
-                assertEquals(Thread.State.NEW, t2.getState());
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+            Thread thread1 = factory.newThread(() -> {
+                Thread thread2 = factory.newThread(LockSupport::park);
+                assertEquals(Thread.State.NEW, thread2.getState());
 
                 // start t2 to make it runnable
-                t2.start();
+                thread2.start();
                 try {
-                    assertEquals(Thread.State.RUNNABLE, t2.getState());
+                    assertEquals(Thread.State.RUNNABLE, thread2.getState());
 
                     // yield to allow t2 to run and park
                     Thread.yield();
-                    assertEquals(Thread.State.WAITING, t2.getState());
+                    assertEquals(Thread.State.WAITING, thread2.getState());
                 } finally {
                     // unpark t2 to make it runnable again
-                    LockSupport.unpark(t2);
+                    LockSupport.unpark(thread2);
                 }
 
                 // t2 should be runnable (not mounted)
-                assertEquals(Thread.State.RUNNABLE, t2.getState());
+                assertEquals(Thread.State.RUNNABLE, thread2.getState());
 
                 completed.set(true);
             });
-            t1.join();
+            thread1.start();
+            thread1.join();
         }
         assertTrue(completed.get() == true);
     }
 
     /**
-     * Test Thread::getState when thread is waiting to enter a monitor.
+     * Test Thread::getState when thread is blocked waiting to enter a monitor.
      */
-    @Test
-    void testGetState5() throws Exception {
-        var started = new CountDownLatch(1);
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetState5(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var thread = Thread.ofVirtual().unstarted(() -> {
-            started.countDown();
-            synchronized (lock) { }
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    synchronized (lock) { }
+                });
+            } else {
+                ready.set(true);
+                synchronized (lock) { }
+            }
         });
         synchronized (lock) {
             thread.start();
-            started.await();
+            awaitTrue(ready);
 
             // wait for thread to block
             await(thread, Thread.State.BLOCKED);
@@ -1762,16 +1768,35 @@ void testGetState5() throws Exception {
     /**
      * Test Thread::getState when thread is waiting in Object.wait.
      */
-    @Test
-    void testGetState6() throws Exception {
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetState6(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
             synchronized (lock) {
-                try { lock.wait(); } catch (InterruptedException e) { }
+                try {
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait();
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait();
+                    }
+                } catch (InterruptedException e) { }
             }
         });
         try {
             // wait for thread to wait
+            awaitTrue(ready);
             await(thread, Thread.State.WAITING);
+
+            // notify, thread should block trying to reenter
+            synchronized (lock) {
+                lock.notifyAll();
+                await(thread, Thread.State.BLOCKED);
+            }
         } finally {
             thread.interrupt();
             thread.join();
@@ -1781,18 +1806,35 @@ void testGetState6() throws Exception {
     /**
      * Test Thread::getState when thread is waiting in Object.wait(millis).
      */
-    @Test
-    void testGetState7() throws Exception {
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetState7(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
             synchronized (lock) {
                 try {
-                    lock.wait(Long.MAX_VALUE);
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait(Long.MAX_VALUE);
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait(Long.MAX_VALUE);
+                    }
                 } catch (InterruptedException e) { }
             }
         });
         try {
-            // wait for thread to wait
+            // wait for thread to timed-wait
+            awaitTrue(ready);
             await(thread, Thread.State.TIMED_WAITING);
+
+            // notify, thread should block trying to reenter
+            synchronized (lock) {
+                lock.notifyAll();
+                await(thread, Thread.State.BLOCKED);
+            }
         } finally {
             thread.interrupt();
             thread.join();
@@ -1933,7 +1975,7 @@ void testHoldsLock2() throws Exception {
      * Test Thread::getStackTrace on unstarted thread.
      */
     @Test
-    void testGetStackTrace1() {
+    void testGetStackTraceUnstarted() {
         var thread = Thread.ofVirtual().unstarted(() -> { });
         StackTraceElement[] stack = thread.getStackTrace();
         assertTrue(stack.length == 0);
@@ -1943,136 +1985,224 @@ void testGetStackTrace1() {
      * Test Thread::getStackTrace on thread that has been started but has not run.
      */
     @Test
-    void testGetStackTrace2() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+    void testGetStackTraceStarted() throws Exception {
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         Executor scheduler = task -> { };
-        Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-        Thread thread = builder.start(() -> { });
+        ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+        Thread thread = factory.newThread(() -> { });
+        thread.start();
         StackTraceElement[] stack = thread.getStackTrace();
         assertTrue(stack.length == 0);
     }
 
     /**
-     * Test Thread::getStackTrace on running thread.
+     * Test Thread::getStackTrace on thread that is runnable-mounted.
      */
     @Test
-    void testGetStackTrace3() throws Exception {
-        var sel = Selector.open();
-        var thread = Thread.ofVirtual().start(() -> {
-            try { sel.select(); } catch (Exception e) { }
-        });
-        try {
-            while (!contains(thread.getStackTrace(), "select")) {
-                assertTrue(thread.isAlive());
-                Thread.sleep(20);
+    void testGetStackTraceRunnableMounted() throws Exception {
+        var ready = new AtomicBoolean();
+        var done = new AtomicBoolean();
+
+        class Foo {
+            void spinUntilDone() {
+                ready.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
+                }
             }
+        }
+
+        Foo foo = new Foo();
+        var thread = Thread.ofVirtual().start(foo::spinUntilDone);
+        try {
+            awaitTrue(ready);
+            StackTraceElement[] stack = thread.getStackTrace();
+            assertTrue(contains(stack, Foo.class.getName() + ".spinUntilDone"));
         } finally {
-            sel.close();
+            done.set(true);
             thread.join();
         }
     }
 
     /**
-     * Test Thread::getStackTrace on thread waiting in Object.wait.
+     * Test Thread::getStackTrace on thread that is runnable-unmounted.
      */
     @Test
-    void testGetStackTrace4() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
-        try (ForkJoinPool pool = new ForkJoinPool(1)) {
-            AtomicReference<Thread> ref = new AtomicReference<>();
-            Executor scheduler = task -> {
-                pool.submit(() -> {
-                    ref.set(Thread.currentThread());
-                    task.run();
-                });
-            };
+    void testGetStackTraceRunnableUnmounted() throws Exception {
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
 
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            Thread vthread = builder.start(() -> {
-                synchronized (lock) {
-                    try {
-                        lock.wait();
-                    } catch (Exception e) { }
+        // custom scheduler with one carrier thread
+        try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+
+            // start thread1 to park
+            Thread thread1 = factory.newThread(LockSupport::park);
+            thread1.start();
+            await(thread1, Thread.State.WAITING);
+
+            // start thread2 to spin and pin the carrier thread
+            var started = new AtomicBoolean();
+            var done = new AtomicBoolean();
+            Thread thread2 = factory.newThread(() -> {
+                started.set(true);
+                while (!done.get()) {
+                    Thread.onSpinWait();
                 }
             });
+            thread2.start();
+            awaitTrue(started);
 
-            // get carrier Thread
-            Thread carrier;
-            while ((carrier = ref.get()) == null) {
-                Thread.sleep(20);
-            }
+            try {
+                // unpark thread1, it should be "stuck" in runnable state
+                // (the carrier thread is pinned, no other virtual thread can run)
+                LockSupport.unpark(thread1);
+                assertEquals(Thread.State.RUNNABLE, thread1.getState());
 
-            // wait for virtual thread to block in wait
-            await(vthread, Thread.State.WAITING);
+                // print thread1's stack trace
+                StackTraceElement[] stack = thread1.getStackTrace();
+                assertTrue(contains(stack, "LockSupport.park"));
 
-            // get stack trace of both carrier and virtual thread
-            StackTraceElement[] carrierStackTrace = carrier.getStackTrace();
-            StackTraceElement[] vthreadStackTrace = vthread.getStackTrace();
+            } finally {
+                done.set(true);
+            }
+        }
+    }
 
-            // allow virtual thread to terminate
-            synchronized (lock) {
-                lock.notifyAll();
+    /**
+     * Test Thread::getStackTrace on thread blocked on monitor enter.
+     */
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetStackTraceBlocked(boolean pinned) throws Exception {
+        class Foo {
+            void enter() {
+                synchronized (this) { }
+            }
+        }
+        Foo foo = new Foo();
+        var ready = new AtomicBoolean();
+        var thread = Thread.ofVirtual().unstarted(() -> {
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    foo.enter();
+                });
+            } else {
+                ready.set(true);
+                foo.enter();
             }
+        });
+        synchronized (foo) {
+            thread.start();
+            awaitTrue(ready);
 
-            // check carrier thread's stack trace
-            assertTrue(contains(carrierStackTrace, "java.util.concurrent.ForkJoinPool.runWorker"));
-            assertFalse(contains(carrierStackTrace, "java.lang.Object.wait"));
+            // wait for thread to block
+            await(thread, Thread.State.BLOCKED);
 
-            // check virtual thread's stack trace
-            assertFalse(contains(vthreadStackTrace, "java.util.concurrent.ForkJoinPool.runWorker"));
-            assertTrue(contains(vthreadStackTrace, "java.lang.Object.wait"));
+            StackTraceElement[] stack = thread.getStackTrace();
+            assertTrue(contains(stack, Foo.class.getName() + ".enter"));
         }
+        thread.join();
     }
 
     /**
-     * Test Thread::getStackTrace on parked thread.
+     * Test Thread::getStackTrace when thread is waiting in Object.wait.
      */
-    @Test
-    void testGetStackTrace5() throws Exception {
-        var thread = Thread.ofVirtual().start(LockSupport::park);
-        await(thread, Thread.State.WAITING);
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetStackTraceWaiting(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
+        var thread = Thread.ofVirtual().start(() -> {
+            synchronized (lock) {
+                try {
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait();
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait();
+                    }
+                } catch (InterruptedException e) { }
+            }
+        });
         try {
+            // wait for thread to wait
+            awaitTrue(ready);
+            await(thread, Thread.State.WAITING);
+
             StackTraceElement[] stack = thread.getStackTrace();
-            assertTrue(contains(stack, "LockSupport.park"));
+            assertTrue(contains(stack, "Object.wait"));
         } finally {
-            LockSupport.unpark(thread);
+            thread.interrupt();
             thread.join();
         }
     }
 
     /**
-     * Test Thread::getStackTrace on timed-parked thread.
+     * Test Thread::getStackTrace when thread is waiting in timed-Object.wait.
      */
-    @Test
-    void testGetStackTrace6() throws Exception {
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetStackTraceTimedWaiting(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
-            LockSupport.parkNanos(Long.MAX_VALUE);
+            synchronized (lock) {
+                try {
+                    if (pinned) {
+                        VThreadPinner.runPinned(() -> {
+                            ready.set(true);
+                            lock.wait(Long.MAX_VALUE);
+                        });
+                    } else {
+                        ready.set(true);
+                        lock.wait(Long.MAX_VALUE);
+                    }
+                } catch (InterruptedException e) { }
+            }
         });
-        await(thread, Thread.State.TIMED_WAITING);
         try {
+            // wait for thread to wait
+            awaitTrue(ready);
+            await(thread, Thread.State.TIMED_WAITING);
+
             StackTraceElement[] stack = thread.getStackTrace();
-            assertTrue(contains(stack, "LockSupport.parkNanos"));
+            assertTrue(contains(stack, "Object.wait"));
         } finally {
-            LockSupport.unpark(thread);
+            thread.interrupt();
             thread.join();
         }
     }
 
     /**
-     * Test Thread::getStackTrace on parked thread that is pinned.
+     * Test Thread::getStackTrace when thread in park.
      */
-    @Test
-    void testGetStackTrace7() throws Exception {
-        AtomicBoolean done = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetStackTraceParked(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
+        var done = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
-            VThreadPinner.runPinned(() -> {
+            if (pinned) {
+                VThreadPinner.runPinned(() -> {
+                    ready.set(true);
+                    while (!done.get()) {
+                        LockSupport.park();
+                    }
+                });
+            } else {
+                ready.set(true);
                 while (!done.get()) {
                     LockSupport.park();
                 }
-            });
+            }
         });
-        await(thread, Thread.State.WAITING);
         try {
+            // wait for thread to park
+            awaitTrue(ready);
+            await(thread, Thread.State.WAITING);
+
             StackTraceElement[] stack = thread.getStackTrace();
             assertTrue(contains(stack, "LockSupport.park"));
         } finally {
@@ -2083,20 +2213,33 @@ void testGetStackTrace7() throws Exception {
     }
 
     /**
-     * Test Thread::getStackTrace on timed-parked thread that is pinned.
+     * Test Thread::getStackTrace when thread in timed-park.
      */
-    @Test
-    void testGetStackTrace8() throws Exception {
-        AtomicBoolean done = new AtomicBoolean();
+    @ParameterizedTest
+    @ValueSource(booleans = { true, false })
+    void testGetStackTraceTimedPark(boolean pinned) throws Exception {
+        var ready = new AtomicBoolean();
+        var done = new AtomicBoolean();
         var thread = Thread.ofVirtual().start(() -> {
-            VThreadPinner.runPinned(() -> {
+            if (pinned) {
+                ready.set(true);
+                VThreadPinner.runPinned(() -> {
+                    while (!done.get()) {
+                        LockSupport.parkNanos(Long.MAX_VALUE);
+                    }
+                });
+            } else {
+                ready.set(true);
                 while (!done.get()) {
                     LockSupport.parkNanos(Long.MAX_VALUE);
                 }
-            });
+            }
         });
-        await(thread, Thread.State.TIMED_WAITING);
         try {
+            // wait for thread to park
+            awaitTrue(ready);
+            await(thread, Thread.State.TIMED_WAITING);
+
             StackTraceElement[] stack = thread.getStackTrace();
             assertTrue(contains(stack, "LockSupport.parkNanos"));
         } finally {
@@ -2110,7 +2253,7 @@ void testGetStackTrace8() throws Exception {
      * Test Thread::getStackTrace on terminated thread.
      */
     @Test
-    void testGetStackTrace9() throws Exception {
+    void testGetStackTraceTerminated() throws Exception {
         var thread = Thread.ofVirtual().start(() -> { });
         thread.join();
         StackTraceElement[] stack = thread.getStackTrace();
@@ -2133,7 +2276,7 @@ void testGetAllStackTraces1() throws Exception {
      */
     @Test
     void testGetAllStackTraces2() throws Exception {
-        assumeTrue(ThreadBuilders.supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         try (ForkJoinPool pool = new ForkJoinPool(1)) {
             AtomicReference<Thread> ref = new AtomicReference<>();
             Executor scheduler = task -> {
@@ -2143,14 +2286,15 @@ void testGetAllStackTraces2() throws Exception {
                 });
             };
 
-            Thread.Builder builder = ThreadBuilders.virtualThreadBuilder(scheduler);
-            Thread vthread = builder.start(() -> {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
+            Thread vthread = factory.newThread(() -> {
                 synchronized (lock) {
                     try {
                         lock.wait();
                     } catch (Exception e) { }
                 }
             });
+            vthread.start();
 
             // get carrier Thread
             Thread carrier;
@@ -2168,8 +2312,9 @@ void testGetAllStackTraces2() throws Exception {
             synchronized (lock) {
                 lock.notifyAll();
             }
+            vthread.join();
 
-            // get stack trace for the carrier thread
+            // stack trace for the carrier thread
             StackTraceElement[] stackTrace = map.get(carrier);
             assertNotNull(stackTrace);
             assertTrue(contains(stackTrace, "java.util.concurrent.ForkJoinPool"));
@@ -2417,6 +2562,15 @@ Throwable exception() {
         }
     }
 
+    /**
+     * Waits for the boolean value to become true.
+     */
+    private static void awaitTrue(AtomicBoolean ref) throws Exception {
+        while (!ref.get()) {
+            Thread.sleep(20);
+        }
+    }
+
     /**
      * Waits for the given thread to reach a given state.
      */
diff --git a/test/jdk/java/lang/Thread/virtual/VirtualThreadPinnedEventThrows.java b/test/jdk/java/lang/Thread/virtual/VirtualThreadPinnedEventThrows.java
index 1ae73b280cb..0c5f1c3d6b4 100644
--- a/test/jdk/java/lang/Thread/virtual/VirtualThreadPinnedEventThrows.java
+++ b/test/jdk/java/lang/Thread/virtual/VirtualThreadPinnedEventThrows.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,7 +24,7 @@
 /**
  * @test
  * @summary Test parking when pinned and emitting the JFR VirtualThreadPinnedEvent throws
- * @modules java.base/jdk.internal.event
+ * @modules java.base/java.lang:+open java.base/jdk.internal.event
  * @library /test/lib
  * @compile/module=java.base jdk/internal/event/VirtualThreadPinnedEvent.java
  * @run junit/othervm --enable-native-access=ALL-UNNAMED VirtualThreadPinnedEventThrows
@@ -36,12 +36,22 @@
 import java.util.concurrent.locks.LockSupport;
 import jdk.internal.event.VirtualThreadPinnedEvent;
 
+import jdk.test.lib.thread.VThreadRunner;
 import jdk.test.lib.thread.VThreadPinner;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeAll;
 import static org.junit.jupiter.api.Assertions.*;
 
 class VirtualThreadPinnedEventThrows {
 
+    @BeforeAll
+    static void setup() {
+        // need >=2 carriers for testing pinning when main thread is a virtual thread
+        if (Thread.currentThread().isVirtual()) {
+            VThreadRunner.ensureParallelism(2);
+        }
+    }
+
     /**
      * Test parking when pinned and creating the VirtualThreadPinnedEvent fails with OOME.
      */
diff --git a/test/jdk/java/lang/Thread/virtual/stress/TimedGet.java b/test/jdk/java/lang/Thread/virtual/stress/CompletableFutureTimedGet.java
similarity index 79%
rename from test/jdk/java/lang/Thread/virtual/stress/TimedGet.java
rename to test/jdk/java/lang/Thread/virtual/stress/CompletableFutureTimedGet.java
index 60125e1ac56..29ad90895f5 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/TimedGet.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/CompletableFutureTimedGet.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,17 +25,18 @@
  * @test
  * @summary Stress parking with CompletableFuture timed get
  * @requires vm.debug != true & vm.continuations
- * @run main/othervm -Xmx1g TimedGet 100000
+ * @run main/othervm -Xmx1g CompletableFutureTimedGet 100000
  */
 
 import java.time.Duration;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
-public class TimedGet {
+public class CompletableFutureTimedGet {
 
     static final String RESULT = "foo";
 
@@ -77,30 +78,27 @@ public static void main(String... args) throws InterruptedException {
 
         // wait for all threads to terminate
         long lastTimestamp = System.currentTimeMillis();
-        int i = 0;
-        while (i < threadCount) {
-            Thread t = threads.get(i);
-            boolean terminated;
-            if (t.isAlive()) {
-                terminated = t.join(Duration.ofMillis(500));
-
-                // print trace message so the output tracks progress
-                long currentTime = System.currentTimeMillis();
-                if ((currentTime - lastTimestamp) > 500) {
-                    System.out.println(completed.get());
-                    lastTimestamp = currentTime;
+        boolean done;
+        do {
+            done = true;
+            for (Thread t : threads) {
+                if (!t.join(Duration.ofSeconds(1))) {
+                    done = false;
                 }
-            } else {
-                terminated = true;
             }
-            if (terminated) {
-                i++;
+
+            // print trace message so the output tracks progress
+            long currentTime = System.currentTimeMillis();
+            if (done || ((currentTime - lastTimestamp) > 500)) {
+                System.out.format("%s => completed %d of %d%n",
+                        Instant.now(), completed.get(), threadCount);
+                lastTimestamp = currentTime;
             }
-        }
+
+        } while (!done);
 
         // all tasks should have completed successfully
         int completedCount = completed.get();
-        System.out.println(completedCount);
         if (completedCount != threadCount) {
             throw new RuntimeException("completed = " + completedCount);
         }
diff --git a/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenBlocking.java b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenBlocking.java
new file mode 100644
index 00000000000..a5aea9ee398
--- /dev/null
+++ b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenBlocking.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @summary Stress test Thread.getStackTrace on virtual threads that are blocking or
+ *     blocked on monitorenter
+ * @requires vm.debug != true
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run main/othervm GetStackTraceALotWhenBlocking 500000
+ */
+
+/*
+ * @test
+ * @requires vm.debug == true & vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run main/othervm/timeout=300 GetStackTraceALotWhenBlocking 50000
+ */
+
+import java.time.Instant;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.atomic.AtomicBoolean;
+import jdk.test.lib.thread.VThreadRunner;
+
+public class GetStackTraceALotWhenBlocking {
+
+    public static void main(String[] args) throws Exception {
+        // need at least two carriers
+        VThreadRunner.ensureParallelism(2);
+
+        int iterations = args.length > 0 ? Integer.parseInt(args[0]) : 100_000;
+
+        var done = new AtomicBoolean();
+        var lock = new Object();
+
+        Runnable task = () -> {
+            long count = 0L;
+            while (!done.get()) {
+                synchronized (lock) {
+                    pause();
+                }
+                count++;
+            }
+            System.out.format("%s %s => %d loops%n", Instant.now(), Thread.currentThread(), count);
+        };
+
+        var thread1 = Thread.ofVirtual().start(task);
+        var thread2 = Thread.ofVirtual().start(task);
+        try {
+            for (int i = 1; i <= iterations; i++) {
+                if ((i % 10_000) == 0) {
+                    System.out.format("%s => %d of %d%n", Instant.now(), i, iterations);
+                }
+
+                thread1.getStackTrace();
+                pause();
+                thread2.getStackTrace();
+                pause();
+            }
+        } finally {
+            done.set(true);
+            thread1.join();
+            thread2.join();
+        }
+    }
+
+    private static void pause() {
+        if (ThreadLocalRandom.current().nextBoolean()) {
+            Thread.onSpinWait();
+        } else {
+            Thread.yield();
+        }
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALot.java b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenParking.java
similarity index 85%
rename from test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALot.java
rename to test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenParking.java
index c86daf1bc6f..d35f39a991a 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALot.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenParking.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,30 +23,32 @@
 
 /**
  * @test
- * @summary Stress test asynchronous Thread.getStackTrace
+ * @summary Stress test asynchronous Thread.getStackTrace when parking
  * @requires vm.debug != true & vm.continuations
  * @modules java.base/java.lang:+open
- * @compile GetStackTraceALot.java ../ThreadBuilders.java
- * @run main GetStackTraceALot
+ * @library /test/lib
+ * @run main GetStackTraceALotWhenParking
  */
 
 /**
  * @test
  * @requires vm.debug == true & vm.continuations
  * @modules java.base/java.lang:+open
- * @compile GetStackTraceALot.java ../ThreadBuilders.java
- * @run main/timeout=300 GetStackTraceALot 1000
+ * @library /test/lib
+ * @run main/timeout=300 GetStackTraceALotWhenParking 1000
  */
 
 import java.time.Duration;
+import java.time.Instant;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.LockSupport;
+import jdk.test.lib.thread.VThreadScheduler;
 
-public class GetStackTraceALot {
+public class GetStackTraceALotWhenParking {
     static class RoundRobinExecutor implements Executor, AutoCloseable {
         private final ExecutorService[] executors;
         private int next;
@@ -83,7 +85,9 @@ public static void main(String[] args) throws Exception {
         AtomicInteger count = new AtomicInteger();
 
         try (RoundRobinExecutor executor = new RoundRobinExecutor()) {
-            Thread thread = ThreadBuilders.virtualThreadBuilder(executor).start(() -> {
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(executor);
+
+            Thread thread = factory.newThread(() -> {
                 while (count.incrementAndGet() < ITERATIONS) {
                     long start = System.nanoTime();
                     while ((System.nanoTime() - start) < SPIN_NANOS) {
@@ -92,6 +96,7 @@ public static void main(String[] args) throws Exception {
                     LockSupport.parkNanos(500_000);
                 }
             });
+            thread.start();
 
             long start = System.nanoTime();
             while (thread.isAlive()) {
@@ -99,7 +104,7 @@ public static void main(String[] args) throws Exception {
                 // printStackTrace(stackTrace);
                 Thread.sleep(5);
                 if ((System.nanoTime() - start) > 500_000_000) {
-                    System.out.println(count.get());
+                    System.out.format("%s => %d of %d%n", Instant.now(), count.get(), ITERATIONS);
                     start = System.nanoTime();
                 }
             }
diff --git a/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenPinned.java b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenPinned.java
index 35986718a38..d7e6c3a8de4 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenPinned.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/GetStackTraceALotWhenPinned.java
@@ -28,7 +28,7 @@
  * @requires vm.debug != true
  * @modules java.base/java.lang:+open
  * @library /test/lib
- * @run main/othervm GetStackTraceALotWhenPinned 500000
+ * @run main/othervm --enable-native-access=ALL-UNNAMED GetStackTraceALotWhenPinned 500000
  */
 
 /*
@@ -36,7 +36,7 @@
  * @requires vm.debug == true
  * @modules java.base/java.lang:+open
  * @library /test/lib
- * @run main/othervm/timeout=300 GetStackTraceALotWhenPinned 200000
+ * @run main/othervm/timeout=300 --enable-native-access=ALL-UNNAMED GetStackTraceALotWhenPinned 200000
  */
 
 import java.time.Instant;
@@ -79,7 +79,7 @@ public static void main(String[] args) throws Exception {
         });
 
         long lastTimestamp = System.currentTimeMillis();
-        for (int i = 0; i < iterations; i++) {
+        for (int i = 1; i <= iterations; i++) {
             // wait for virtual thread to arrive
             barrier.await();
 
@@ -87,8 +87,8 @@ public static void main(String[] args) throws Exception {
             LockSupport.unpark(thread);
 
             long currentTime = System.currentTimeMillis();
-            if ((currentTime - lastTimestamp) > 500) {
-                System.out.format("%s %d remaining ...%n", Instant.now(), (iterations - i));
+            if (i == iterations || ((currentTime - lastTimestamp) > 500)) {
+                System.out.format("%s => %d of %d%n", Instant.now(), i, iterations);
                 lastTimestamp = currentTime;
             }
         }
diff --git a/test/jdk/java/lang/Thread/virtual/stress/PinALot.java b/test/jdk/java/lang/Thread/virtual/stress/PinALot.java
index a420ebb330e..7f95847fc76 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/PinALot.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/PinALot.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -46,17 +46,17 @@
 public class PinALot {
 
     public static void main(String[] args) throws Exception {
-        int iterations = 1_000_000;
+        int iterations;
         if (args.length > 0) {
             iterations = Integer.parseInt(args[0]);
+        } else {
+            iterations = 1_000_000;
         }
-        final int ITERATIONS = iterations;
 
         AtomicInteger count = new AtomicInteger();
-
         Thread thread = Thread.ofVirtual().start(() -> {
             VThreadPinner.runPinned(() -> {
-                while (count.incrementAndGet() < ITERATIONS) {
+                while (count.incrementAndGet() < iterations) {
                     LockSupport.parkNanos(1);
                 }
             });
@@ -65,12 +65,12 @@ public static void main(String[] args) throws Exception {
         boolean terminated;
         do {
             terminated = thread.join(Duration.ofSeconds(1));
-            System.out.println(Instant.now() + " => " + count.get());
+            System.out.println(Instant.now() + " => " + count.get() + " of " + iterations);
         } while (!terminated);
 
         int countValue = count.get();
-        if (countValue != ITERATIONS) {
-            throw new RuntimeException("count = " + countValue);
+        if (countValue != iterations) {
+            throw new RuntimeException("Thread terminated, count=" + countValue);
         }
     }
 }
diff --git a/test/jdk/java/lang/Thread/virtual/stress/PingPong.java b/test/jdk/java/lang/Thread/virtual/stress/PingPong.java
index 404444b99ce..2266d192fca 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/PingPong.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/PingPong.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@
  */
 
 import java.time.Duration;
+import java.time.Instant;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.LinkedTransferQueue;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -91,11 +92,12 @@ public static void main(String[] args) throws Exception {
         boolean terminated;
         do {
             terminated = t1.join(Duration.ofMillis(500));
-            if (terminated)
+            if (terminated) {
                 terminated = t2.join(Duration.ofMillis(500));
-            System.out.format("%d %s%n", count1.get(), count2.get());
+            }
+            System.out.format("%s => T1 %d of %d, T2 %d of %d%n",
+                    Instant.now(), count1.get(), iterations, count2.get(), iterations);
         } while (!terminated);
-
     }
 
     interface Exchanger<E> {
diff --git a/test/jdk/java/lang/Thread/virtual/stress/Skynet.java b/test/jdk/java/lang/Thread/virtual/stress/Skynet.java
index ee45fc827b0..5b63fe84b1d 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/Skynet.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/Skynet.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -69,7 +69,7 @@ static void skynet(int num, long expected) {
         long end = System.currentTimeMillis();
         System.out.format("Result: %d in %s ms%n", sum, (end-start));
         if (sum != expected)
-            throw new AssertionError("unexpected result!");
+            throw new RuntimeException("Expected " + expected);
     }
 
     static void skynet(Channel<Long> result, int num, int size, int div) {
diff --git a/test/jdk/java/lang/Thread/virtual/stress/SleepALot.java b/test/jdk/java/lang/Thread/virtual/stress/SleepALot.java
index 12771ab499a..ed1c985ba7c 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/SleepALot.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/SleepALot.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -41,16 +41,16 @@
 public class SleepALot {
 
     public static void main(String[] args) throws Exception {
-        int iterations = 1_000_000;
+        int iterations;
         if (args.length > 0) {
             iterations = Integer.parseInt(args[0]);
+        } else {
+            iterations = 1_000_000;
         }
-        final int ITERATIONS = iterations;
 
         AtomicInteger count = new AtomicInteger();
-
         Thread thread = Thread.ofVirtual().start(() -> {
-            while (count.incrementAndGet() < ITERATIONS) {
+            while (count.incrementAndGet() < iterations) {
                 try {
                     Thread.sleep(Duration.ofNanos(100));
                 } catch (InterruptedException ignore) { }
@@ -60,12 +60,12 @@ public static void main(String[] args) throws Exception {
         boolean terminated;
         do {
             terminated = thread.join(Duration.ofSeconds(1));
-            System.out.println(Instant.now() + " => " + count.get());
+            System.out.println(Instant.now() + " => " + count.get() + " of " + iterations);
         } while (!terminated);
 
         int countValue = count.get();
-        if (countValue != ITERATIONS) {
-            throw new RuntimeException("count = " + countValue);
+        if (countValue != iterations) {
+            throw new RuntimeException("Thread terminated, count=" + countValue);
         }
     }
 }
diff --git a/test/jdk/java/lang/Thread/virtual/stress/TimedWaitALot.java b/test/jdk/java/lang/Thread/virtual/stress/TimedWaitALot.java
new file mode 100644
index 00000000000..2a2fce62d62
--- /dev/null
+++ b/test/jdk/java/lang/Thread/virtual/stress/TimedWaitALot.java
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test id=timeout
+ * @summary Stress test timed-Object.wait
+ * @run main/othervm TimedWaitALot 200
+ */
+
+/*
+ * @test id=timeout-notify
+ * @summary Test timed-Object.wait where the waiting thread is awakened with Object.notify
+ *     at around the same time that the timeout expires.
+ * @run main/othervm TimedWaitALot 200 true false
+ */
+
+/*
+ * @test id=timeout-interrupt
+ * @summary Test timed-Object.wait where the waiting thread is awakened with Thread.interrupt
+ *     at around the same time that the timeout expires.
+ * @run main/othervm TimedWaitALot 200 false true
+ */
+
+/*
+ * @test id=timeout-notify-interrupt
+ * @summary Test timed-Object.wait where the waiting thread is awakened with Object.notify
+ *     and Thread.interrupt at around the same time that the timeout expires.
+ * @run main/othervm TimedWaitALot 100 true true
+ */
+
+import java.time.Instant;
+import java.util.concurrent.Executors;
+import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class TimedWaitALot {
+    public static void main(String[] args) throws Exception {
+        int iterations = Integer.parseInt(args[0]);
+        boolean notify = args.length >= 2 && "true".equals(args[1]);
+        boolean interrupt = args.length >=3 && "true".equals(args[2]);
+
+        // test all timeouts concurrently
+        int[] timeouts = { 10, 20, 50, 100 };
+        for (int i = 1; i <= iterations; i++) {
+            System.out.println(Instant.now() + " => " + i + " of " + iterations);
+            test(notify, interrupt, timeouts);
+        }
+    }
+
+    /**
+     * Start a first virtual thread to wait in Object.wait(millis).
+     * If {@code notify} is true, start a virtual thread to use Object.notifyAll at around
+     * the same time that the timeout expires.
+     * If {@code interrupt} is true, start virtual thread to interrupts the first virtual
+     * thread at around the same time as the timeout expires.
+     */
+    static void test(boolean notify, boolean interrupt, int... timeouts) throws Exception {
+        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
+            for (int timeout : timeouts) {
+                var queue = new SynchronousQueue<Thread>();
+                var lock = new Object();
+
+                // virtual thread waits with Object.wait(timeout)
+                executor.submit(() -> {
+                    queue.put(Thread.currentThread());
+                    synchronized (lock) {
+                        lock.wait(timeout);
+                    }
+                    return null;
+                });
+
+                // wait for thread to start
+                Thread thread = queue.take();
+
+                // start thread to Object.notifyAll at around time that the timeout expires
+                if (notify) {
+                    if (ThreadLocalRandom.current().nextBoolean()) {
+                        synchronized (lock) {
+                            sleepLessThan(timeout);
+                            lock.notifyAll();
+                        }
+                    } else {
+                        sleepLessThan(timeout);
+                        synchronized (lock) {
+                            lock.notifyAll();
+                        }
+                    }
+                }
+
+                // start thread to interrupt first thread at around time that the timeout expires
+                if (interrupt) {
+                    executor.submit(() -> {
+                        sleepLessThan(timeout);
+                        thread.interrupt();
+                        return null;
+                    });
+                }
+            }
+        }
+    }
+
+    /**
+     * Sleeps for just less than the given timeout, in millis.
+     */
+    private static void sleepLessThan(long timeout) throws InterruptedException {
+        int delta = ThreadLocalRandom.current().nextInt(10);
+        Thread.sleep(timeout - delta);
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/stress/YieldALot.java b/test/jdk/java/lang/Thread/virtual/stress/YieldALot.java
index 3eabfff1c4c..b793993a1b7 100644
--- a/test/jdk/java/lang/Thread/virtual/stress/YieldALot.java
+++ b/test/jdk/java/lang/Thread/virtual/stress/YieldALot.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,7 @@
  * @test
  * @summary Stress test Thread.yield
  * @requires vm.debug != true
- * @run main YieldALot 350000
+ * @run main YieldALot 500000
  */
 
 /*
@@ -35,34 +35,35 @@
  */
 
 import java.time.Duration;
+import java.time.Instant;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class YieldALot {
 
     public static void main(String[] args) throws Exception {
-        int iterations = 1_000_000;
+        int iterations;
         if (args.length > 0) {
             iterations = Integer.parseInt(args[0]);
+        } else {
+            iterations = 1_000_000;
         }
-        final int ITERATIONS = iterations;
 
         AtomicInteger count = new AtomicInteger();
-
         Thread thread = Thread.ofVirtual().start(() -> {
-            while (count.incrementAndGet() < ITERATIONS) {
+            while (count.incrementAndGet() < iterations) {
                 Thread.yield();
             }
         });
 
         boolean terminated;
         do {
-            terminated = thread.join(Duration.ofMillis(500));
-            System.out.println(count.get());
+            terminated = thread.join(Duration.ofSeconds(1));
+            System.out.println(Instant.now() + " => " + count.get() + " of " + iterations);
         } while (!terminated);
 
         int countValue = count.get();
-        if (countValue != ITERATIONS) {
-            throw new RuntimeException("count = " + countValue);
+        if (countValue != iterations) {
+            throw new RuntimeException("Thread terminated, count=" + countValue);
         }
     }
 }
diff --git a/test/jdk/java/lang/instrument/RetransformRecordAnnotation.java b/test/jdk/java/lang/instrument/RetransformRecordAnnotation.java
deleted file mode 100644
index 90d76d1f923..00000000000
--- a/test/jdk/java/lang/instrument/RetransformRecordAnnotation.java
+++ /dev/null
@@ -1,187 +0,0 @@
-/*
- * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/*
- * @test
- * @bug 8315575 8328137
- * @summary test that records with invisible annotation can be retransformed
- *
- * @library /test/lib
- * @run shell MakeJAR.sh retransformAgent
- * @run main/othervm -javaagent:retransformAgent.jar -Xlog:redefine+class=trace RetransformRecordAnnotation
- * @run main/othervm -javaagent:retransformAgent.jar -XX:+PreserveAllAnnotations -Xlog:redefine+class=trace RetransformRecordAnnotation
- */
-
-import java.io.File;
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-import java.lang.instrument.ClassFileTransformer;
-import java.nio.file.Files;
-import java.security.ProtectionDomain;
-
-public class RetransformRecordAnnotation extends AInstrumentationTestCase {
-
-    @Target({ElementType.TYPE_PARAMETER, ElementType.TYPE_USE})
-    @Retention(RetentionPolicy.RUNTIME)
-    @interface RuntimeTypeAnno {}
-
-    @Retention(RetentionPolicy.RUNTIME)
-    @interface RuntimeParamAnno {
-        String s() default "foo";
-    }
-
-    @Target({ElementType.TYPE_PARAMETER, ElementType.TYPE_USE})
-    @Retention(RetentionPolicy.CLASS)
-    @interface ClassTypeAnno {}
-
-    @Retention(RetentionPolicy.CLASS)
-    @interface ClassParamAnno {
-        String s() default "bar";
-    }
-
-    @RuntimeTypeAnno
-    @RuntimeParamAnno(s = "1")
-    public record VisibleAnnos(@RuntimeTypeAnno @RuntimeParamAnno(s = "2") Object o, Object other) {
-    }
-
-    @ClassTypeAnno
-    @ClassParamAnno(s = "3")
-    public record InvisibleAnnos(@ClassTypeAnno @ClassParamAnno(s = "4") Object o, Object other) {
-    }
-
-    @RuntimeTypeAnno
-    @RuntimeParamAnno(s = "5")
-    @ClassTypeAnno
-    @ClassParamAnno(s = "6")
-    public record MixedAnnos(@RuntimeTypeAnno @RuntimeParamAnno(s = "7")
-                             @ClassTypeAnno @ClassParamAnno(s = "8") Object o, Object other) {
-    }
-
-    public static void main (String[] args) throws Throwable {
-        ATestCaseScaffold test = new RetransformRecordAnnotation();
-        test.beVerbose();
-        test.runTest();
-    }
-
-    private Transformer transformer;
-
-    public RetransformRecordAnnotation() throws Throwable {
-        super("RetransformRecordAnnotation");
-    }
-
-    private void log(Object o) {
-        System.out.println(String.valueOf(o));
-    }
-
-    // Retransforms target class using provided class bytes;
-    private void retransform(Class targetClass, byte[] classBytes) throws Throwable {
-        transformer.prepare(targetClass, classBytes);
-        fInst.retransformClasses(targetClass);
-        assertTrue(targetClass.getName() + " was not seen by transform()",
-                   transformer.getSeenClassBytes() != null);
-    }
-
-    protected final void doRunTest() throws Throwable {
-        transformer = new Transformer();
-        fInst.addTransformer(transformer, true);
-
-        {
-            log("Sanity: retransform to original class bytes");
-            retransform(InvisibleAnnos.class, loadClassBytes(InvisibleAnnos.class));
-            log("");
-        }
-
-        // The following testcases use null as new class bytes (i.e. no transform is performed).
-        // However, it is enough for testing purposes as the JvmtiClassFileReconstituter is still involved
-        // in preparation of the initial class bytes.
-        {
-            log("Test: retransform VisibleAnnos to null");
-            retransform(VisibleAnnos.class, null);
-            log("");
-        }
-
-        {
-            log("Test: retransform InvisibleAnnos to null");
-            retransform(InvisibleAnnos.class, null);
-            log("");
-        }
-
-        {
-            log("Test: retransform MixedAnnos to null");
-            retransform(MixedAnnos.class, null);
-            log("");
-        }
-    }
-
-    private byte[] loadClassBytes(Class cls) throws Exception {
-        String classFileName = cls.getName() + ".class";
-        File classFile = new File(System.getProperty("test.classes", "."), classFileName);
-        log("Reading test class from " + classFile);
-        byte[] classBytes = Files.readAllBytes(classFile.toPath());
-        log("Read " + classBytes.length + " bytes.");
-        return classBytes;
-    }
-
-    public class Transformer implements ClassFileTransformer {
-        private String targetClassName;
-        private byte[] seenClassBytes;
-        private byte[] newClassBytes;
-
-        public Transformer() {
-        }
-
-        // Prepares transformer for Instrumentation.retransformClasses.
-        public void prepare(Class targetClass, byte[] classBytes) {
-            targetClassName = targetClass.getName();
-            newClassBytes = classBytes;
-            seenClassBytes = null;
-        }
-
-        byte[] getSeenClassBytes() {
-            return seenClassBytes;
-        }
-
-        public String toString() {
-            return Transformer.this.getClass().getName();
-        }
-
-        public byte[] transform(ClassLoader loader, String className,
-            Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) {
-
-            if (className.equals(targetClassName)) {
-                log(this + ".transform() sees '" + className
-                        + "' of " + classfileBuffer.length + " bytes.");
-                seenClassBytes = classfileBuffer;
-                if (newClassBytes != null) {
-                    log(this + ".transform() sets new classbytes for '" + className
-                            + "' of " + newClassBytes.length + " bytes.");
-                }
-                return newClassBytes;
-            }
-
-            return null;
-        }
-    }
-}
diff --git a/test/jdk/java/lang/management/ThreadMXBean/LockedMonitorInNative.java b/test/jdk/java/lang/management/ThreadMXBean/LockedMonitorInNative.java
new file mode 100644
index 00000000000..e1e490aa040
--- /dev/null
+++ b/test/jdk/java/lang/management/ThreadMXBean/LockedMonitorInNative.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @summary Test ThreadMXBean.getLockedMonitors returns information about an object
+ *    monitor lock entered with a synchronized native method or JNI MonitorEnter
+ * @run junit/othervm LockedMonitorInNative
+ */
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+import java.util.Arrays;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeAll;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class LockedMonitorInNative {
+
+    @BeforeAll
+    static void setup() throws Exception {
+        System.loadLibrary("LockedMonitorInNative");
+    }
+
+    /**
+     * Test ThreadMXBean.getLockedMonitors returns information about an object
+     * monitor lock entered with a synchronized native method.
+     */
+    @Test
+    void testSynchronizedNative() {
+        Object lock = this;
+        runWithSynchronizedNative(() -> {
+            assertTrue(holdsLock(lock), "Thread does not hold lock");
+        });
+    }
+
+    /**
+     * Test ThreadMXBean.getLockedMonitors returns information about an object
+     * monitor lock entered with JNI MonitorEnter.
+     */
+    @Test
+    void testMonitorEnteredInNative() {
+        var lock = new Object();
+        runWithMonitorEnteredInNative(lock, () -> {
+            assertTrue(holdsLock(lock), "Thread does not hold lock");
+        });
+    }
+
+    private boolean holdsLock(Object lock) {
+        int hc = System.identityHashCode(lock);
+        long tid = Thread.currentThread().threadId();
+        ThreadInfo ti = ManagementFactory.getPlatformMXBean(ThreadMXBean.class)
+                .getThreadInfo(new long[] { tid }, true, true)[0];
+        return Arrays.stream(ti.getLockedMonitors())
+                .anyMatch(mi -> mi.getIdentityHashCode() == hc);
+    }
+
+    /**
+     * Invokes the given task's run method while holding the monitor for "this".
+     */
+    private synchronized native void runWithSynchronizedNative(Runnable task);
+
+    /**
+     * Invokes the given task's run method while holding the monitor for the given
+     * object. The monitor is entered with JNI MonitorEnter, and exited with JNI MonitorExit.
+     */
+    private native void runWithMonitorEnteredInNative(Object lock, Runnable task);
+
+    /**
+     * Called from native methods to run the given task.
+     */
+    private void run(Runnable task) {
+        task.run();
+    }
+}
diff --git a/test/jdk/java/lang/management/ThreadMXBean/VirtualThreads.java b/test/jdk/java/lang/management/ThreadMXBean/VirtualThreads.java
index 35fe819313a..7830c93ac13 100644
--- a/test/jdk/java/lang/management/ThreadMXBean/VirtualThreads.java
+++ b/test/jdk/java/lang/management/ThreadMXBean/VirtualThreads.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -41,19 +41,20 @@
 import java.lang.management.ManagementFactory;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.InvocationTargetException;
 import java.nio.channels.Selector;
 import java.util.Arrays;
 import java.util.Set;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.LockSupport;
 import java.util.stream.Collectors;
 
+import jdk.test.lib.thread.VThreadPinner;
 import jdk.test.lib.thread.VThreadRunner;
+import jdk.test.lib.thread.VThreadScheduler;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -195,7 +196,7 @@ void testGetThreadInfo4(int maxDepth) {
      */
     @Test
     void testGetThreadInfoCarrierThread() throws Exception {
-        assumeTrue(supportsCustomScheduler(), "No support for custom schedulers");
+        assumeTrue(VThreadScheduler.supportsCustomScheduler(), "No support for custom schedulers");
         try (ExecutorService pool = Executors.newFixedThreadPool(1)) {
             var carrierRef = new AtomicReference<Thread>();
             Executor scheduler = (task) -> {
@@ -204,19 +205,30 @@ void testGetThreadInfoCarrierThread() throws Exception {
                     task.run();
                 });
             };
+            ThreadFactory factory = VThreadScheduler.virtualThreadFactory(scheduler);
 
             // start virtual thread so carrier Thread can be captured
-            virtualThreadBuilder(scheduler).start(() -> { }).join();
+            Thread thread = factory.newThread(() -> { });
+            thread.start();
+            thread.join();
             Thread carrier = carrierRef.get();
             assertTrue(carrier != null && !carrier.isVirtual());
 
             try (Selector sel = Selector.open()) {
-                // start virtual thread that blocks in a native method
-                virtualThreadBuilder(scheduler).start(() -> {
+                String selClassName = sel.getClass().getName();
+
+                // start virtual thread that blocks while pinned
+                Thread vthread = factory.newThread(() -> {
                     try {
-                        sel.select();
+                        VThreadPinner.runPinned(sel::select);
                     } catch (Exception e) { }
                 });
+                vthread.start();
+
+                // wait for virtual thread to block in select
+                while (!contains(vthread.getStackTrace(), selClassName)) {
+                    Thread.sleep(20);
+                }
 
                 // invoke getThreadInfo get and check the stack trace
                 long tid = carrier.getId();
@@ -225,7 +237,7 @@ void testGetThreadInfoCarrierThread() throws Exception {
                 // should only see carrier frames
                 StackTraceElement[] stack = info.getStackTrace();
                 assertTrue(contains(stack, "java.util.concurrent.ThreadPoolExecutor"));
-                assertFalse(contains(stack, "java.nio.channels.Selector"));
+                assertFalse(contains(stack, selClassName));
 
                 // carrier should not be holding any monitors
                 assertEquals(0, info.getLockedMonitors().length);
@@ -351,40 +363,4 @@ private static boolean contains(StackTraceElement[] stack, String className) {
                 .map(StackTraceElement::getClassName)
                 .anyMatch(className::equals);
     }
-
-    /**
-     * Returns a builder to create virtual threads that use the given scheduler.
-     * @throws UnsupportedOperationException if there is no support for custom schedulers
-     */
-    private static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
-        Thread.Builder.OfVirtual builder = Thread.ofVirtual();
-        try {
-            Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
-            Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
-            ctor.setAccessible(true);
-            return (Thread.Builder.OfVirtual) ctor.newInstance(scheduler);
-        } catch (InvocationTargetException e) {
-            Throwable cause = e.getCause();
-            if (cause instanceof RuntimeException re) {
-                throw re;
-            }
-            throw new RuntimeException(e);
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    /**
-     * Return true if custom schedulers are supported.
-     */
-    private static boolean supportsCustomScheduler() {
-        try (var pool = Executors.newCachedThreadPool()) {
-            try {
-                virtualThreadBuilder(pool);
-                return true;
-            } catch (UnsupportedOperationException e) {
-                return false;
-            }
-        }
-    }
 }
diff --git a/test/jdk/java/lang/management/ThreadMXBean/libLockedMonitorInNative.c b/test/jdk/java/lang/management/ThreadMXBean/libLockedMonitorInNative.c
new file mode 100644
index 00000000000..20975188907
--- /dev/null
+++ b/test/jdk/java/lang/management/ThreadMXBean/libLockedMonitorInNative.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "jni.h"
+
+JNIEXPORT void JNICALL
+Java_LockedMonitorInNative_runWithSynchronizedNative(JNIEnv *env, jobject obj, jobject task) {
+    jclass clazz = (*env)->GetObjectClass(env, obj);
+    jmethodID mid = (*env)->GetMethodID(env, clazz, "run", "(Ljava/lang/Runnable;)V");
+    if (mid != NULL) {
+        (*env)->CallVoidMethod(env, obj, mid, task);
+    }
+}
+
+JNIEXPORT void JNICALL
+Java_LockedMonitorInNative_runWithMonitorEnteredInNative(JNIEnv *env, jobject obj, jobject lock, jobject task) {
+    jclass clazz = (*env)->GetObjectClass(env, obj);
+    jmethodID mid = (*env)->GetMethodID(env, clazz, "run", "(Ljava/lang/Runnable;)V");
+    if (mid != NULL && (*env)->MonitorEnter(env, lock) == 0) {
+        (*env)->CallVoidMethod(env, obj, mid, task);
+        (*env)->MonitorExit(env, lock);  // can be called with pending exception
+    }
+}
diff --git a/test/jdk/javax/swing/JColorChooser/Test6977726.java b/test/jdk/javax/swing/JColorChooser/Test6977726.java
index a79931c93eb..1ec72036f14 100644
--- a/test/jdk/javax/swing/JColorChooser/Test6977726.java
+++ b/test/jdk/javax/swing/JColorChooser/Test6977726.java
@@ -41,7 +41,14 @@ public static void main(String[] args) throws Exception {
         String instructions = """
                 Check that there is a panel with "Text Preview Panel" text
                 and with title "Preview" in the JColorChooser.
-                Test passes if the panel is as described, test fails otherwise.""";
+                Test passes if the panel is as described, test fails otherwise.
+
+                Note: "Preview" title is not applicable for GTK Look and Feel.""";
+
+        // In case this test is run with GTK L&F, the preview panel title
+        // is missing due to the "ColorChooser.showPreviewPanelText" property
+        // which is set to "Boolean.FALSE" for GTK L&F. Test instructions are
+        // modified to reflect that "Preview" title is not applicable for GTK L&F.
 
         PassFailJFrame.builder()
                 .title("Test6977726")
diff --git a/test/jdk/javax/swing/text/html/HTMLDocument/HTMLTextDecorationNone.java b/test/jdk/javax/swing/text/html/HTMLDocument/HTMLTextDecorationNone.java
new file mode 100644
index 00000000000..318626e5110
--- /dev/null
+++ b/test/jdk/javax/swing/text/html/HTMLDocument/HTMLTextDecorationNone.java
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.awt.Dimension;
+import java.awt.Graphics;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+import javax.imageio.ImageIO;
+import javax.swing.JEditorPane;
+import javax.swing.text.View;
+import javax.swing.text.html.CSS;
+
+/*
+ * @test
+ * @bug 8335967
+ * @summary Tests 'text-decoration: none' is respected
+ * @run main HTMLTextDecorationNone
+ */
+public final class HTMLTextDecorationNone {
+    private static final String HTML = """
+            <!DOCTYPE html>
+            <html lang="en">
+            <head>
+                <meta charset="UTF-8">
+                <title>text-decoration: none (&lt;a&gt;)</title>
+                <style>
+                    a.none { text-decoration: none }
+                </style>
+            </head>
+            <body>
+            <p><a href="https://openjdk.org/">underlined</a></p>
+            <p><a href="https://openjdk.org/" style="text-decoration: none">not underlined</a></p>
+            <p><a href="https://openjdk.org/" class="none">not underlined</a></p>
+            <p style="text-decoration: underline"><a
+                   href="https://openjdk.org/" style="text-decoration: none">underlined?</a></p>
+            <p style="text-decoration: underline"><a
+                   href="https://openjdk.org/" class="none">underlined?</a></p>
+            </body>
+            </html>
+            """;
+
+    private static final boolean[] underlined = {true, false, false, true, true};
+
+    public static void main(String[] args) {
+        final JEditorPane html = new JEditorPane("text/html", HTML);
+        html.setEditable(false);
+
+        final Dimension size = html.getPreferredSize();
+        html.setSize(size);
+
+        BufferedImage image = new BufferedImage(size.width, size.height,
+                                                BufferedImage.TYPE_INT_RGB);
+        Graphics g = image.createGraphics();
+        // Paint the editor pane to ensure all views are created
+        html.paint(g);
+        g.dispose();
+
+        int errorCount = 0;
+        String firstError = null;
+
+        System.out.println("----- Views -----");
+        final View bodyView = html.getUI()
+                                  .getRootView(html)
+                                  .getView(1)
+                                  .getView(1);
+        for (int i = 0; i < bodyView.getViewCount(); i++) {
+            View pView = bodyView.getView(i);
+            View contentView = getContentView(pView);
+
+            Object decorationAttr =
+                    contentView.getAttributes()
+                               .getAttribute(CSS.Attribute.TEXT_DECORATION);
+            String decoration = decorationAttr == null
+                                ? "none" : decorationAttr.toString();
+
+            System.out.println(i + ": " + decoration);
+            if (decoration.contains("underline") != underlined[i]) {
+                errorCount++;
+                if (firstError == null) {
+                    firstError = "Line " + i + ": " + decoration + " vs "
+                                 + (underlined[i] ? "underline" : "none");
+                }
+            }
+        }
+
+        if (errorCount > 0) {
+            saveImage(image);
+            throw new RuntimeException(errorCount + " error(s) found, "
+                                       + "the first one: " + firstError);
+        }
+    }
+
+    private static View getContentView(View parent) {
+        View view = parent.getView(0);
+        return view.getViewCount() > 0
+               ? getContentView(view)
+               : view;
+    }
+
+    private static void saveImage(BufferedImage image) {
+        try {
+            ImageIO.write(image, "png",
+                          new File("html.png"));
+        } catch (IOException ignored) { }
+    }
+}
diff --git a/test/jdk/jdk/classfile/AccessFlagsTest.java b/test/jdk/jdk/classfile/AccessFlagsTest.java
index 97c0d97f8f9..379dcddb9c8 100644
--- a/test/jdk/jdk/classfile/AccessFlagsTest.java
+++ b/test/jdk/jdk/classfile/AccessFlagsTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,9 @@
  * @summary Testing ClassFile AccessFlags.
  * @run junit AccessFlagsTest
  */
+import java.lang.classfile.ClassFile;
+import java.lang.constant.ClassDesc;
+import java.util.Arrays;
 import java.util.EnumSet;
 import java.util.Random;
 import java.util.Set;
@@ -34,6 +37,10 @@
 import java.util.function.IntFunction;
 import java.lang.reflect.AccessFlag;
 import java.lang.classfile.AccessFlags;
+
+import static java.lang.classfile.ClassFile.ACC_STATIC;
+import static java.lang.constant.ConstantDescs.CD_int;
+import static java.lang.constant.ConstantDescs.MTD_void;
 import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.provider.EnumSource;
@@ -45,15 +52,38 @@ class AccessFlagsTest {
     @EnumSource(names = { "CLASS", "METHOD", "FIELD" })
     void testRandomAccessFlagsConverions(AccessFlag.Location ctx) {
         IntFunction<AccessFlags> intFactory = switch (ctx) {
-            case CLASS -> AccessFlags::ofClass;
-            case METHOD -> AccessFlags::ofMethod;
-            case FIELD -> AccessFlags::ofField;
+            case CLASS -> v -> {
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb -> clb.withFlags(v));
+                return ClassFile.of().parse(bytes).flags();
+            };
+            case METHOD -> v -> {
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb ->
+                        clb.withMethod("test", MTD_void, v & ACC_STATIC, mb -> mb.withFlags(v)));
+                return ClassFile.of().parse(bytes).methods().getFirst().flags();
+            };
+            case FIELD -> v -> {
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb ->
+                        clb.withField("test", CD_int, fb -> fb.withFlags(v)));
+                return ClassFile.of().parse(bytes).fields().getFirst().flags();
+            };
             default -> null;
         };
         Function<AccessFlag[], AccessFlags> flagsFactory = switch (ctx) {
-            case CLASS -> AccessFlags::ofClass;
-            case METHOD -> AccessFlags::ofMethod;
-            case FIELD -> AccessFlags::ofField;
+            case CLASS -> v -> {
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb -> clb.withFlags(v));
+                return ClassFile.of().parse(bytes).flags();
+            };
+            case METHOD -> v -> {
+                boolean hasStatic = Arrays.stream(v).anyMatch(f -> f == AccessFlag.STATIC);
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb ->
+                        clb.withMethod("test", MTD_void, hasStatic ? ACC_STATIC : 0, mb -> mb.withFlags(v)));
+                return ClassFile.of().parse(bytes).methods().getFirst().flags();
+            };
+            case FIELD -> v -> {
+                var bytes = ClassFile.of().build(ClassDesc.of("Test"), clb ->
+                        clb.withField("test", CD_int, fb -> fb.withFlags(v)));
+                return ClassFile.of().parse(bytes).fields().getFirst().flags();
+            };
             default -> null;
         };
 
@@ -72,11 +102,11 @@ void testRandomAccessFlagsConverions(AccessFlag.Location ctx) {
 
     @Test
     void testInvalidFlagsUse() {
-        assertAll(
-            () -> assertThrowsForInvalidFlagsUse(AccessFlags::ofClass),
-            () -> assertThrowsForInvalidFlagsUse(AccessFlags::ofField),
-            () -> assertThrowsForInvalidFlagsUse(AccessFlags::ofMethod)
-        );
+        ClassFile.of().build(ClassDesc.of("Test"), clb -> {
+            assertThrowsForInvalidFlagsUse(clb::withFlags);
+            clb.withMethod("test", MTD_void, ACC_STATIC, mb -> assertThrowsForInvalidFlagsUse(mb::withFlags));
+            clb.withField("test", CD_int, fb -> assertThrowsForInvalidFlagsUse(fb::withFlags));
+        });
     }
 
     void assertThrowsForInvalidFlagsUse(Consumer<AccessFlag[]> factory) {
diff --git a/test/jdk/jdk/classfile/BuilderBlockTest.java b/test/jdk/jdk/classfile/BuilderBlockTest.java
index c8e13b79f72..30a44491e6c 100644
--- a/test/jdk/jdk/classfile/BuilderBlockTest.java
+++ b/test/jdk/jdk/classfile/BuilderBlockTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,36 +23,49 @@
 
 /*
  * @test
+ * @bug 8337225
  * @summary Testing ClassFile builder blocks.
  * @run junit BuilderBlockTest
  */
+import java.io.IOException;
+import java.lang.classfile.Attributes;
+import java.lang.classfile.ClassFile;
+import java.lang.classfile.ClassTransform;
+import java.lang.classfile.CodeBuilder;
+import java.lang.classfile.CodeElement;
+import java.lang.classfile.CodeTransform;
+import java.lang.classfile.Label;
+import java.lang.classfile.MethodModel;
+import java.lang.classfile.MethodTransform;
+import java.lang.classfile.Opcode;
+import java.lang.classfile.TypeKind;
+import java.lang.classfile.constantpool.StringEntry;
+import java.lang.classfile.instruction.ConstantInstruction;
 import java.lang.constant.ClassDesc;
-
-import static java.lang.constant.ConstantDescs.*;
-
 import java.lang.constant.MethodTypeDesc;
+import java.lang.reflect.AccessFlag;
 import java.lang.reflect.Method;
+import java.net.URI;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 
 import helpers.ByteArrayClassLoader;
-import java.lang.classfile.AccessFlags;
-import java.lang.reflect.AccessFlag;
-import java.lang.classfile.ClassFile;
-import java.lang.classfile.Label;
-import java.lang.classfile.Opcode;
-import java.lang.classfile.TypeKind;
 import jdk.internal.classfile.impl.LabelImpl;
-import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
 
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
+import static java.lang.constant.ConstantDescs.CD_int;
+import static java.lang.constant.ConstantDescs.CD_void;
+
+import static org.junit.jupiter.api.Assertions.*;
+
 /**
  * BuilderBlockTest
  */
 class BuilderBlockTest {
 
-    static final String testClassName = "AdaptCodeTest$TestClass";
-    static final Path testClassPath = Paths.get("target/test-classes/" + testClassName + ".class");
+    static final String testClassName = "BuilderBlockTest$TestClass";
+    static final Path testClassPath = Path.of(URI.create(BuilderBlockTest.class.getResource(testClassName + ".class").toString()));
 
     @Test
     void testStartEnd() throws Exception {
@@ -104,7 +117,7 @@ void testIfThenReturn() throws Exception {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(xb -> xb.iload(0)
                                                     .ifThen(xxb -> xxb.iconst_1().ireturn())
                                                     .iconst_2()
@@ -123,7 +136,7 @@ void testIfThenElseReturn() throws Exception {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(xb -> xb.iload(0)
                                                     .ifThenElse(xxb -> xxb.iconst_1().ireturn(),
                                                                 xxb -> xxb.iconst_2().ireturn())));
@@ -141,7 +154,7 @@ void testIfThenBadOpcode()  {
         ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int, CD_int),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                    ACC_PUBLIC | ACC_STATIC,
                     mb -> mb.withCode(xb -> {
                         xb.iload(0);
                         xb.iload(1);
@@ -161,7 +174,7 @@ void testIfThenElseImplicitBreak() throws Exception {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(xb -> xb.iload(0)
                                                     .ifThenElse(xxb -> xxb.iconst_1().istore(2),
                                                                 xxb -> xxb.iconst_2().istore(2))
@@ -181,7 +194,7 @@ void testIfThenElseExplicitBreak() throws Exception {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                    ACC_PUBLIC | ACC_STATIC,
                     mb -> mb.withCode(xb -> xb.iload(0)
                             .ifThenElse(xxb -> xxb.iconst_1().istore(2).goto_(xxb.breakLabel()),
                                     xxb -> xxb.iconst_2().istore(2).goto_(xxb.breakLabel()))
@@ -200,7 +213,7 @@ void testIfThenElseOpcode() throws Exception {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int, CD_int),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                    ACC_PUBLIC | ACC_STATIC,
                     mb -> mb.withCode(xb ->
                             xb.iload(0)
                             .iload(1)
@@ -225,7 +238,7 @@ void testIfThenElseBadOpcode()  {
         ClassFile.of().build(ClassDesc.of("Foo"), cb -> {
             cb.withFlags(AccessFlag.PUBLIC);
             cb.withMethod("foo", MethodTypeDesc.of(CD_int, CD_int, CD_int),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                    ACC_PUBLIC | ACC_STATIC,
                     mb -> mb.withCode(xb -> {
                         xb.iload(0);
                         xb.iload(1);
@@ -305,4 +318,81 @@ void testAllocateLocalIfThen() {
                           }));
         });
     }
+
+    private static final CodeTransform ALLOCATE_LOCAL_EXAMINER = CodeTransform.ofStateful(() -> new CodeTransform() {
+        boolean foundItem = false;
+
+        @Override
+        public void atStart(CodeBuilder builder) {
+            foundItem = false;
+        }
+
+        @Override
+        public void accept(CodeBuilder cob, CodeElement coe) {
+            cob.with(coe);
+            if (coe instanceof ConstantInstruction.LoadConstantInstruction ldc
+                    && ldc.constantEntry() instanceof StringEntry se
+                    && se.utf8().equalsString("Output")) {
+                assertFalse(foundItem);
+                foundItem = true;
+                var i = cob.allocateLocal(TypeKind.IntType);
+                assertEquals(7, i, "Allocated new int slot");
+            }
+        }
+
+        @Override
+        public void atEnd(CodeBuilder builder) {
+            assertTrue(foundItem);
+        }
+    });
+
+    // Test updating local variable slot management from
+    // source code models in transformingCode;
+    // CodeBuilder.transform(CodeModel, CodeTransform) is
+    // not managed for now
+    @Test
+    void testAllocateLocalTransformingCodeAttribute() throws IOException {
+        var cf = ClassFile.of();
+        var code = cf.parse(testClassPath)
+                .methods()
+                .stream()
+                .filter(f -> f.methodName().equalsString("work"))
+                .findFirst()
+                .orElseThrow()
+                .findAttribute(Attributes.code())
+                .orElseThrow();
+        ClassFile.of().build(ClassDesc.of("Foo"), cb -> cb
+                .withMethod("foo", MethodTypeDesc.ofDescriptor("(IJI)V"), 0, mb -> mb
+                        .transformCode(code, ALLOCATE_LOCAL_EXAMINER)));
+    }
+
+    @Test
+    void testAllocateLocalTransformingBufferedCode() throws IOException {
+        var cf = ClassFile.of();
+        var testClass = cf.parse(testClassPath);
+        ClassTransform bufferingTransform = (clb, cle) -> {
+            if (cle instanceof MethodModel mm && mm.methodName().equalsString("work")) {
+                clb.withMethodBody(mm.methodName(), mm.methodType(), mm.flags().flagsMask(), cob -> {
+                    int d = cob.allocateLocal(TypeKind.IntType);
+                    int e = cob.allocateLocal(TypeKind.IntType);
+
+                    assertEquals(5, d);
+                    assertEquals(6, e);
+
+                    mm.code().ifPresent(code -> code.forEach(cob));
+                });
+            }
+        };
+        cf.transformClass(testClass, bufferingTransform.andThen(ClassTransform.transformingMethods(MethodTransform.transformingCode(ALLOCATE_LOCAL_EXAMINER))));
+    }
+
+    public static class TestClass {
+        public void work(int a, long b, int c) {
+            int d = Math.addExact(a, 25);
+            int e = Math.multiplyExact(d, c);
+            System.out.println("Output");
+            System.out.println(e + b);
+            throw new IllegalArgumentException("foo");
+        }
+    }
 }
diff --git a/test/jdk/jdk/classfile/BuilderTryCatchTest.java b/test/jdk/jdk/classfile/BuilderTryCatchTest.java
index 666b36e11a7..192125c4bb6 100644
--- a/test/jdk/jdk/classfile/BuilderTryCatchTest.java
+++ b/test/jdk/jdk/classfile/BuilderTryCatchTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,7 +27,6 @@
  * @run junit BuilderTryCatchTest
  */
 
-import java.lang.classfile.AccessFlags;
 import java.lang.classfile.ClassFile;
 import java.lang.classfile.CodeBuilder;
 import java.lang.classfile.CompoundElement;
@@ -35,6 +34,9 @@
 import java.lang.classfile.TypeKind;
 import java.lang.classfile.instruction.BranchInstruction;
 import java.lang.classfile.instruction.ExceptionCatch;
+
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
 
@@ -43,7 +45,6 @@
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
-import java.lang.reflect.AccessFlag;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
@@ -184,7 +185,7 @@ void testTryEmptyCatch() {
     void testEmptyTry() {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("C"), cb -> {
             cb.withMethod("main", MethodTypeDesc.of(CD_String, CD_String.arrayType()),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(), mb -> {
+                    ACC_PUBLIC | ACC_STATIC, mb -> {
                         mb.withCode(xb -> {
                             int stringSlot = xb.allocateLocal(TypeKind.ReferenceType);
                             xb.loadConstant("S");
@@ -215,7 +216,7 @@ void testEmptyTry() {
     void testLocalAllocation() throws Throwable {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("C"), cb -> {
             cb.withMethod("main", MethodTypeDesc.of(CD_String, CD_String.arrayType()),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(), mb -> {
+                    ACC_PUBLIC | ACC_STATIC, mb -> {
                         mb.withCode(xb -> {
                             int stringSlot = xb.allocateLocal(TypeKind.ReferenceType);
                             xb.loadConstant("S");
@@ -278,7 +279,7 @@ void testLocalAllocation() throws Throwable {
     static byte[] generateTryCatchMethod(Consumer<CodeBuilder.CatchBuilder> c) {
         byte[] bytes = ClassFile.of().build(ClassDesc.of("C"), cb -> {
             cb.withMethod("main", MethodTypeDesc.of(CD_String, CD_String.arrayType()),
-                    AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(), mb -> {
+                    ACC_PUBLIC | ACC_STATIC, mb -> {
                         mb.withCode(xb -> {
                             int stringSlot = xb.allocateLocal(TypeKind.ReferenceType);
                             xb.loadConstant("S");
diff --git a/test/jdk/jdk/classfile/CorpusTest.java b/test/jdk/jdk/classfile/CorpusTest.java
index a2af1667978..631e2f8afaa 100644
--- a/test/jdk/jdk/classfile/CorpusTest.java
+++ b/test/jdk/jdk/classfile/CorpusTest.java
@@ -39,6 +39,7 @@
 import org.junit.jupiter.api.parallel.ExecutionMode;
 
 import java.io.ByteArrayInputStream;
+import java.lang.classfile.attribute.CodeAttribute;
 import java.util.*;
 
 import static helpers.ClassRecord.assertEqualsDeep;
@@ -222,9 +223,11 @@ void testNullAdaptations(Path path) throws Exception {
             var m1 = itStack.next();
             var m2 = itNoStack.next();
             var text1 = m1.methodName().stringValue() + m1.methodType().stringValue() + ": "
-                      + m1.code().map(c -> c.maxLocals() + " / " + c.maxStack()).orElse("-");
+                      + m1.code().map(CodeAttribute.class::cast)
+                                 .map(c -> c.maxLocals() + " / " + c.maxStack()).orElse("-");
             var text2 = m2.methodName().stringValue() + m2.methodType().stringValue() + ": "
-                      + m2.code().map(c -> c.maxLocals() + " / " + c.maxStack()).orElse("-");
+                      + m2.code().map(CodeAttribute.class::cast)
+                                 .map(c -> c.maxLocals() + " / " + c.maxStack()).orElse("-");
             assertEquals(text1, text2);
         }
         assertFalse(itNoStack.hasNext());
diff --git a/test/jdk/jdk/classfile/DiscontinuedInstructionsTest.java b/test/jdk/jdk/classfile/DiscontinuedInstructionsTest.java
index 9070f0b1d45..5e51e585634 100644
--- a/test/jdk/jdk/classfile/DiscontinuedInstructionsTest.java
+++ b/test/jdk/jdk/classfile/DiscontinuedInstructionsTest.java
@@ -26,6 +26,7 @@
  * @summary Testing ClassFile handling JSR and RET instructions.
  * @run junit DiscontinuedInstructionsTest
  */
+import java.lang.classfile.attribute.CodeAttribute;
 import java.lang.constant.ClassDesc;
 import java.lang.constant.MethodTypeDesc;
 import java.util.ArrayList;
@@ -63,7 +64,7 @@ void testJsrAndRetProcessing() throws Exception {
                         .pop()
                         .with(DiscontinuedInstruction.RetInstruction.of(355))));
 
-        var c = cc.parse(bytes).methods().get(0).code().get();
+        var c = (CodeAttribute) cc.parse(bytes).methods().get(0).code().get();
         assertEquals(356, c.maxLocals());
         assertEquals(6, c.maxStack());
 
diff --git a/test/jdk/jdk/classfile/LDCTest.java b/test/jdk/jdk/classfile/LDCTest.java
index 1e7639de4bb..7379218840e 100644
--- a/test/jdk/jdk/classfile/LDCTest.java
+++ b/test/jdk/jdk/classfile/LDCTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,6 +27,9 @@
  * @run junit LDCTest
  */
 import java.lang.constant.ClassDesc;
+
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
 import java.lang.constant.MethodTypeDesc;
 
@@ -38,7 +41,6 @@
 import org.junit.jupiter.api.Test;
 import static helpers.TestConstants.MTD_VOID;
 import static java.lang.classfile.Opcode.*;
-import static java.lang.classfile.TypeKind.VoidType;
 import java.lang.classfile.instruction.ConstantInstruction;
 
 class LDCTest {
@@ -56,7 +58,7 @@ void testLDCisConvertedToLDCW() throws Exception {
               )
 
               .withMethod("main", MethodTypeDesc.of(CD_void, CD_String.arrayType()),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(c0 -> {
                                   ConstantPoolBuilder cpb = cb.constantPool();
                                   for (int i = 0; i <= 256/2 + 2; i++) { // two entries per String
diff --git a/test/jdk/jdk/classfile/LowAdaptTest.java b/test/jdk/jdk/classfile/LowAdaptTest.java
index 9fa2620913b..d47141a885a 100644
--- a/test/jdk/jdk/classfile/LowAdaptTest.java
+++ b/test/jdk/jdk/classfile/LowAdaptTest.java
@@ -27,6 +27,9 @@
  * @run junit LowAdaptTest
  */
 import java.lang.constant.ClassDesc;
+
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
 import java.lang.constant.DirectMethodHandleDesc;
 import java.lang.constant.DynamicCallSiteDesc;
@@ -35,7 +38,6 @@
 import java.net.URI;
 import java.nio.file.Paths;
 
-import java.lang.classfile.AccessFlags;
 import java.lang.reflect.AccessFlag;
 import java.lang.classfile.ClassModel;
 import java.lang.classfile.ClassFile;
@@ -75,7 +77,7 @@ void testAdapt() throws Exception {
             cl.methods().forEach(cb::with);
 
             cb.withMethod("doit", MethodTypeDesc.of(CD_int, CD_int),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(xb -> {
                               xb.invokedynamic(indy);
                               xb.astore(1);
diff --git a/test/jdk/jdk/classfile/LvtTest.java b/test/jdk/jdk/classfile/LvtTest.java
index 3d789809798..d95a4fb7b29 100644
--- a/test/jdk/jdk/classfile/LvtTest.java
+++ b/test/jdk/jdk/classfile/LvtTest.java
@@ -35,13 +35,10 @@
 import java.lang.constant.ClassDesc;
 import java.net.URI;
 import java.nio.file.Files;
-import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 
-import java.lang.classfile.AccessFlags;
 import java.lang.classfile.Attributes;
 import java.lang.classfile.attribute.SourceFileAttribute;
 import java.lang.classfile.constantpool.ConstantPoolBuilder;
@@ -58,11 +55,10 @@
 import static helpers.TestConstants.MTD_VOID;
 import static helpers.TestUtil.ExpectedLvRecord;
 import static helpers.TestUtil.ExpectedLvtRecord;
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
 import java.lang.constant.MethodTypeDesc;
-import static java.lang.classfile.Opcode.*;
-import static java.lang.classfile.Opcode.INVOKEVIRTUAL;
-import static java.lang.classfile.TypeKind.VoidType;
 import static org.junit.jupiter.api.Assertions.*;
 
 class LvtTest {
@@ -128,7 +124,7 @@ void testCreateLoadLVT() throws Exception {
                       )
               )
               .withMethod("main", MethodTypeDesc.of(CD_void, CD_String.arrayType()),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb
                               .withCode(c0 -> {
                                   ConstantPoolBuilder cpb = cb.constantPool();
@@ -243,7 +239,7 @@ void testCreateLoadLVTT() throws Exception {
               )
 
               .withMethod("m", MethodTypeDesc.of(CD_Object, CD_Object.arrayType()),
-                          ClassFile.ACC_PUBLIC,
+                          ACC_PUBLIC,
                           mb -> mb.withFlags(AccessFlag.PUBLIC)
                                   .withCode(c0 -> {
                                       ConstantPoolBuilder cpb = cb.constantPool();
diff --git a/test/jdk/jdk/classfile/OneToOneTest.java b/test/jdk/jdk/classfile/OneToOneTest.java
index b20d07025e6..4e21cbebbe3 100644
--- a/test/jdk/jdk/classfile/OneToOneTest.java
+++ b/test/jdk/jdk/classfile/OneToOneTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,18 +27,19 @@
  * @run junit OneToOneTest
  */
 import java.lang.constant.ClassDesc;
+
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
 import java.lang.constant.MethodTypeDesc;
 import java.util.List;
 
-import java.lang.classfile.AccessFlags;
 import java.lang.reflect.AccessFlag;
 import java.lang.classfile.ClassModel;
 import java.lang.classfile.ClassFile;
 import java.lang.classfile.Instruction;
 import java.lang.classfile.Label;
 import java.lang.classfile.MethodModel;
-import java.lang.classfile.TypeKind;
 import java.lang.classfile.attribute.SourceFileAttribute;
 import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
@@ -74,7 +75,7 @@ void testClassWriteRead() {
                                   )
               )
               .withMethod("main", MethodTypeDesc.of(CD_void, CD_String.arrayType()),
-                          AccessFlags.ofMethod(AccessFlag.STATIC, AccessFlag.PUBLIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(c0 -> {
                                                 Label loopTop = c0.newLabel();
                                                 Label loopEnd = c0.newLabel();
diff --git a/test/jdk/jdk/classfile/StackMapsTest.java b/test/jdk/jdk/classfile/StackMapsTest.java
index 211490c3f8e..a5109dd2a18 100644
--- a/test/jdk/jdk/classfile/StackMapsTest.java
+++ b/test/jdk/jdk/classfile/StackMapsTest.java
@@ -30,6 +30,7 @@
  */
 
 import java.lang.classfile.*;
+import java.lang.classfile.attribute.CodeAttribute;
 import java.lang.classfile.components.ClassPrinter;
 import java.net.URI;
 import java.nio.file.FileSystem;
@@ -329,7 +330,7 @@ void testEmptyCounters(ClassFile.StackMapsOption option) {
         var cm = ClassFile.of().parse(bytes);
         for (var method : cm.methods()) {
             var name = method.methodName();
-            var code = method.code().orElseThrow();
+            var code = (CodeAttribute) method.code().orElseThrow();
             if (name.equalsString("a")) {
                 assertEquals(0, code.maxLocals()); // static method
                 assertEquals(0, code.maxStack());
diff --git a/test/jdk/jdk/classfile/SwapTest.java b/test/jdk/jdk/classfile/SwapTest.java
index 10c0d66d513..71ea6189aa6 100644
--- a/test/jdk/jdk/classfile/SwapTest.java
+++ b/test/jdk/jdk/classfile/SwapTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,8 +27,10 @@
  * @run junit SwapTest
  */
 
-import java.lang.classfile.AccessFlags;
 import java.lang.classfile.ClassFile;
+
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
 
@@ -38,9 +40,6 @@
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 
-import static java.lang.reflect.AccessFlag.PUBLIC;
-import static java.lang.reflect.AccessFlag.STATIC;
-
 class SwapTest {
     @Test
     void testTryCatchCatchAll() throws Throwable {
@@ -48,7 +47,7 @@ void testTryCatchCatchAll() throws Throwable {
         MethodTypeDesc mtd = mt.describeConstable().get();
 
         byte[] bytes = ClassFile.of().build(ClassDesc.of("C"), cb -> {
-            cb.withMethodBody("m", mtd, AccessFlags.ofMethod(PUBLIC, STATIC).flagsMask(), xb -> {
+            cb.withMethodBody("m", mtd, ACC_PUBLIC | ACC_STATIC, xb -> {
                         xb.aload(0); // 0
                         xb.aload(1); // 1, 0
                         xb.swap();   // 0, 1
diff --git a/test/jdk/jdk/classfile/WriteTest.java b/test/jdk/jdk/classfile/WriteTest.java
index b4af9135d12..72d847c474c 100644
--- a/test/jdk/jdk/classfile/WriteTest.java
+++ b/test/jdk/jdk/classfile/WriteTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -30,20 +30,16 @@
 import java.lang.constant.MethodTypeDesc;
 
 import helpers.TestConstants;
-import java.lang.classfile.AccessFlags;
 import java.lang.reflect.AccessFlag;
 import java.lang.classfile.ClassFile;
-import java.lang.classfile.TypeKind;
 import java.lang.classfile.Label;
 import java.lang.classfile.attribute.SourceFileAttribute;
 import org.junit.jupiter.api.Test;
 
 import static helpers.TestConstants.MTD_VOID;
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
-import static java.lang.classfile.Opcode.*;
-import static java.lang.classfile.TypeKind.IntType;
-import static java.lang.classfile.TypeKind.ReferenceType;
-import static java.lang.classfile.TypeKind.VoidType;
 
 class WriteTest {
 
@@ -61,7 +57,7 @@ void testJavapWrite() {
                       )
               )
               .withMethod("main", MethodTypeDesc.of(CD_void, CD_String.arrayType()),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(c0 -> {
                                   Label loopTop = c0.newLabel();
                                   Label loopEnd = c0.newLabel();
@@ -102,7 +98,7 @@ void testPrimitiveWrite() {
                       )
               )
               .withMethod("main", MethodTypeDesc.of(CD_void, CD_String.arrayType()),
-                          AccessFlags.ofMethod(AccessFlag.PUBLIC, AccessFlag.STATIC).flagsMask(),
+                          ACC_PUBLIC | ACC_STATIC,
                           mb -> mb.withCode(c0 -> {
                                   Label loopTop = c0.newLabel();
                                   Label loopEnd = c0.newLabel();
diff --git a/test/jdk/jdk/classfile/examples/ExampleGallery.java b/test/jdk/jdk/classfile/examples/ExampleGallery.java
index 7de4a78ffbf..f37f6b1b74d 100644
--- a/test/jdk/jdk/classfile/examples/ExampleGallery.java
+++ b/test/jdk/jdk/classfile/examples/ExampleGallery.java
@@ -207,7 +207,7 @@ public byte[] changeFieldSig(ClassModel cm) {
     public byte[] changeFieldFlags(ClassModel cm) {
         return ClassFile.of().transformClass(cm, ClassTransform.transformingFields((fb, fe) -> {
             switch (fe) {
-                case AccessFlags a -> fb.with(AccessFlags.ofField(a.flagsMask() & ~ClassFile.ACC_PUBLIC & ~ClassFile.ACC_PROTECTED));
+                case AccessFlags a -> fb.withFlags(a.flagsMask() & ~ClassFile.ACC_PUBLIC & ~ClassFile.ACC_PROTECTED);
                 default -> fb.with(fe);
             }
         }));
diff --git a/test/jdk/jdk/internal/misc/ThreadFlock/ThreadFlockTest.java b/test/jdk/jdk/internal/misc/ThreadFlock/ThreadFlockTest.java
index 2f1da20e052..e6bc191a3ba 100644
--- a/test/jdk/jdk/internal/misc/ThreadFlock/ThreadFlockTest.java
+++ b/test/jdk/jdk/internal/misc/ThreadFlock/ThreadFlockTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -426,7 +426,7 @@ void testAwaitAllWithTimeout1(ThreadFactory factory) throws Exception {
             long startMillis = millisTime();
             boolean done = flock.awaitAll(Duration.ofSeconds(30));
             assertTrue(done);
-            checkDuration(startMillis, 1900, 4000);
+            checkDuration(startMillis, 1900, 20_000);
         }
     }
 
@@ -453,7 +453,7 @@ void testAwaitAllWithTimeout2(ThreadFactory factory) throws Exception {
                     flock.awaitAll(Duration.ofSeconds(2));
                     fail("awaitAll did not throw");
                 } catch (TimeoutException e) {
-                    checkDuration(startMillis, 1900, 4000);
+                    checkDuration(startMillis, 1900, 20_000);
                 }
             } finally {
                 latch.countDown();
diff --git a/test/jdk/jdk/jfr/api/settings/TestSettingControl.java b/test/jdk/jdk/jfr/api/settings/TestSettingControl.java
new file mode 100644
index 00000000000..5543953482d
--- /dev/null
+++ b/test/jdk/jdk/jfr/api/settings/TestSettingControl.java
@@ -0,0 +1,319 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jfr.api.settings;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+
+import jdk.jfr.EventType;
+import jdk.jfr.FlightRecorder;
+import jdk.jfr.Recording;
+import jdk.jfr.SettingDescriptor;
+import jdk.jfr.consumer.RecordedEvent;
+import jdk.jfr.consumer.RecordingFile;
+
+/**
+ * @test
+ * @summary Tests that methods on all SettingControls have expected behavior.
+ * @key jfr
+ * @requires vm.hasJFR
+ * @library /test/lib /test/jdk
+ * @run main/othervm jdk.jfr.api.settings.TestSettingControl
+ */
+public class TestSettingControl {
+    record SettingTest(String setting, String defaultValue, String event, List<String> exampleValues) {
+        public String eventSettingName() {
+            return event + "#" + setting;
+        }
+    }
+
+    // Example values should be listed in precedence order with the lowest precedence first.
+    static List<SettingTest> SETTING_TESTS = List.of(
+        new SettingTest("enabled", "false", "jdk.JavaMonitorWait",List.of("false", "true")),
+        new SettingTest("stackTrace", "true", "jdk.JavaMonitorWait", List.of("false", "true")),
+        new SettingTest("threshold", "0 ns", "jdk.JavaMonitorWait", List.of("infinity", "10 ms", "0 ns")),
+        new SettingTest("level", "forRemoval", "jdk.DeprecatedInvocation", List.of("off", "forRemoval")),
+        new SettingTest("period", "everyChunk", "jdk.ExceptionStatistics", List.of("everyChunk", "60 s", "1 s")),
+        new SettingTest("cutoff", "infinity", "jdk.OldObjectSample", List.of("0 ms", "1 s", "infinity")),
+        new SettingTest("throttle", "off", "jdk.ObjectAllocationSample", List.of("off", "100/s", "10/ms"))
+    );
+
+    public static void main(String... args) throws Exception {
+        testTesting();
+        testDefault();
+        testDefaultWithInvalid();
+        testPrecedence();
+        testPrecedenceWithInvalid();
+    }
+
+    // Ensure that all known SettingControl/types are tested at least once
+    private static void testTesting() throws Exception {
+        Set<String> foundSettings = new HashSet<>();
+        for (EventType eventType : allEventTypes()) {
+            for (SettingDescriptor s : eventType.getSettingDescriptors()) {
+                foundSettings.add(s.getName());
+            }
+        }
+        for (SettingTest st : SETTING_TESTS) {
+            foundSettings.remove(st.setting());
+        }
+        if (!foundSettings.isEmpty()) {
+            throw new Exception("All event SettingControls should be tested. Missing test for " + foundSettings);
+        }
+    }
+
+    // Ensure that the default values for all SettingControls are correct
+    private static void testDefault() throws Exception {
+        for (SettingTest settingTest : SETTING_TESTS) {
+            SettingDescriptor s = findSettingDescriptor(settingTest);
+            if (!settingTest.defaultValue().equals(s.getDefaultValue())) {
+                String message = "Incorrect default value " + quote(s.getDefaultValue());
+                message += " for setting " + settingTest.eventSettingName() + ". ";
+                message += "Expected " + quote(settingTest.defaultValue());
+                throw new Exception(message);
+            }
+        }
+    }
+
+    // Ensure that default settings are used if an invalid setting is specified.
+    private static void testDefaultWithInvalid() throws Exception {
+        Map<String, String> settings = createEnabledMap();
+        for (SettingTest settingTest : SETTING_TESTS) {
+            settings.put(settingTest.eventSettingName(), "%#&2672g");
+        }
+        Map<String, String> result = check("testDefaultWithInvalid", List.of(settings));
+        for (var entry : new ArrayList<>(result.entrySet())) {
+            String key = entry.getKey();
+            String removed = result.remove(key);
+            if (removed == null) {
+                throw new Exception("Expected setting " + quote(key) + " to exist");
+            }
+            String setting = key.substring(key.indexOf("#") + 1);
+            SettingTest st = findSettingTest(setting);
+            if (st == null) {
+                throw new Exception("Found unexpected setting " + quote(key));
+            }
+            if (!removed.equals(st.defaultValue())) {
+                String message = "Expected default value " + quote(st.defaultValue());
+                message += " for setting " + quote(setting) + " when";
+                message += " an invalid settings value was specified";
+                throw new Exception(message);
+            }
+        }
+        if (!result.isEmpty()) {
+            throw new Exception("Found unexpected setting when testing preserved default");
+        }
+    }
+
+    // Only enabled events will use settings
+    private static Map<String, String> createEnabledMap() {
+        Map<String, String> settings = new TreeMap<>();
+        for (SettingTest settingTest : SETTING_TESTS) {
+            settings.put(settingTest.event + "#enabled", "true");
+        }
+        return settings;
+    }
+
+    // Ensure that precedence are respected when multiple settings are specified
+    private static void testPrecedence() throws Exception {
+        testPrecedence("testPrecedence");
+    }
+
+    // Ensure that precedence are respected when an incorrect setting is used
+    private static void testPrecedenceWithInvalid() throws Exception {
+        testPrecedence("testPrecedenceWithInvalid");
+    }
+
+    // * * * HELPER METHODS * * *
+
+    private static void testPrecedence(String testName) throws Exception {
+        List<Map<String, String>> settingsList = new ArrayList<>();
+        int maxExamples = 0;
+        for (SettingTest t : SETTING_TESTS) {
+            maxExamples = Math.max(t.exampleValues().size(), maxExamples);
+        }
+        for (int i = 0; i < maxExamples; i++) {
+            Map<String, String> settings = createEnabledMap();
+            for (SettingTest settingTest : SETTING_TESTS) {
+                List<String> examples = settingTest.exampleValues();
+                String name = settingTest.eventSettingName();
+                if (i < examples.size()) {
+                    settings.put(name, examples.get(i));
+                }
+                // Insert the invalid setting first
+                if (testName.contains("Invalid") && i == 0) {
+                    settings.put(name, "%#&2672g");
+                }
+            }
+            settingsList.add(settings);
+        }
+        Map<String, String> results = check(testName, settingsList);
+        Map<String, String> reversed = check(testName + "-reversed", settingsList.reversed());
+        if (!reversed.equals(results)) {
+            throw new Exception("Active settings should not depend on the order event settings are applied");
+        }
+        for (SettingTest t : SETTING_TESTS) {
+            String expected = t.exampleValues().get(t.exampleValues().size() - 1);
+            String found = results.get(t.eventSettingName());
+            if (!expected.equals(found)) {
+                throw new Exception("Expected " + expected + " to be used with setting " + quote(t.setting()) + ", not " + quote(found));
+            }
+        }
+    }
+
+    private static Map<String, String> check(String testName, List<Map<String, String>> settingsList) throws Exception {
+        System.out.println("*** Check for " + testName + " ****");
+        System.out.println("Input:");
+        int index = 0;
+        for (var settings : settingsList) {
+            System.out.println("Setting[" + index + "] = {");
+            for (var e : settings.entrySet()) {
+                System.out.println("  " + e.getKey() + "=" + e.getValue());
+            }
+            System.out.println("}");
+            index++;
+        }
+        int settingsCount = settingsList.size();
+
+        // Start a recording for each settings
+        List<Recording> recordings = new ArrayList<>();
+        for (int i = 0; i < settingsCount; i++) {
+            Recording r = new Recording();
+            Map<String, String> settings = settingsList.get(i);
+            settings.put("jdk.ActiveSetting#enabled", "true");
+            r.setSettings(settings);
+            r.start();
+            recordings.add(r);
+        }
+
+        // Stop all recordings
+        for (Recording r : recordings) {
+            r.stop();
+        }
+
+        // Dump the innermost recording
+        Path p = Path.of("recording.jfr");
+        Recording inner = recordings.get(settingsCount - 1);
+        inner.dump(p);
+
+        // Close all recordings
+        for (Recording r : recordings) {
+            r.close();
+        }
+        System.out.println("Result:");
+        Map<String, String> r = lastSettings(p);
+        for (var e : r.entrySet()) {
+            System.out.println(e.getKey() + "=" + e.getValue());
+        }
+        System.out.println("*************");
+        System.out.println();
+        Files.delete(p);
+        return r;
+    }
+
+    private static SettingTest findSettingTest(String name) throws Exception {
+        for (SettingTest settingTest : SETTING_TESTS) {
+            if (name.equals(settingTest.setting())) {
+                return settingTest;
+            }
+        }
+        return null;
+    }
+
+    private static Map<String, String> lastSettings(Path p) throws Exception {
+        List<RecordedEvent> events = RecordingFile.readAllEvents(p);
+        Instant timestamp = findLastActiveSetting(events);
+        Map<String, String> lastInnerMostSettings = new HashMap<>();
+        for (SettingTest t : SETTING_TESTS) {
+            long id = eventTypeNameToId(t.event());
+            for (RecordedEvent event : events) {
+                if (event.getEventType().getName().equals("jdk.ActiveSetting")) {
+                    if (event.getStartTime().equals(timestamp) && id == event.getLong("id")) {
+                        String name = event.getString("name");
+                        String value = event.getString("value");
+                        if (t.setting.equals(name)) {
+                            String fullName = t.event() + "#" + name;
+                            String previous = lastInnerMostSettings.put(fullName, value);
+                            if (previous != null) {
+                                throw new Exception("Expected only one ActiveSetting event per event setting");
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        return lastInnerMostSettings;
+    }
+
+    private static Instant findLastActiveSetting(List<RecordedEvent> events) {
+        Instant lastTimestamp = null;
+        for (RecordedEvent event : events) {
+            if (event.getEventType().getName().equals("jdk.ActiveSetting")) {
+                Instant t = event.getStartTime();
+                if (lastTimestamp == null || t.isBefore(lastTimestamp)) {
+                    lastTimestamp = t;
+                }
+            }
+        }
+        return lastTimestamp;
+    }
+
+    private static long eventTypeNameToId(String name) throws Exception {
+        for (EventType eventType : allEventTypes()) {
+            if (eventType.getName().equals(name)) {
+                return eventType.getId();
+            }
+        }
+        throw new Exception("Could not find event type with name " + name);
+    }
+
+    private static SettingDescriptor findSettingDescriptor(SettingTest settingTest) throws Exception {
+        for (EventType eventType : allEventTypes()) {
+            if (eventType.getName().equals(settingTest.event())) {
+                for (SettingDescriptor s : eventType.getSettingDescriptors()) {
+                    if (settingTest.setting().equals(s.getName())) {
+                        return s;
+                    }
+                }
+            }
+        }
+        throw new Exception("Could not find setting with name " + settingTest.event() + "#" + settingTest.setting());
+    }
+
+    private static List<EventType> allEventTypes() {
+        return FlightRecorder.getFlightRecorder().getEventTypes();
+    }
+
+    private static String quote(String text) {
+        return "'" + text + "'";
+    }
+}
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestDefNewAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestDefNewAllocationPendingStackTrace.java
index 2f290a748c2..fa91d77e2fb 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestDefNewAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestDefNewAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Serial"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseSerialGC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestDefNewAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseSerialGC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestDefNewAllocationPendingStackTrace
  */
 public class TestDefNewAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1HumongousAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1HumongousAllocationPendingStackTrace.java
index 2df5d95f524..ad633ea26de 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1HumongousAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1HumongousAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "G1"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseG1GC -Xlog:gc* -Xmx64M -XX:InitiatingHeapOccupancyPercent=100 jdk.jfr.event.gc.stacktrace.TestG1HumongousAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseG1GC -Xlog:gc* -Xmx64M -XX:InitiatingHeapOccupancyPercent=100
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestG1HumongousAllocationPendingStackTrace
  */
 public class TestG1HumongousAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1OldAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1OldAllocationPendingStackTrace.java
index 3541f117e1e..1cf75ff8fac 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1OldAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1OldAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "G1"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:MaxNewSize=10M -Xmx128M -XX:+UseG1GC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestG1OldAllocationPendingStackTrace
+ * @run main/othervm -XX:MaxNewSize=10M -Xmx128M -XX:+UseG1GC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestG1OldAllocationPendingStackTrace
  */
 public class TestG1OldAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1YoungAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1YoungAllocationPendingStackTrace.java
index e5b7f849173..7259ff5f445 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1YoungAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestG1YoungAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "G1"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseG1GC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestG1YoungAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseG1GC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestG1YoungAllocationPendingStackTrace
  */
 public class TestG1YoungAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMarkSweepCompactAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMarkSweepCompactAllocationPendingStackTrace.java
index e7f5e709d15..c06862ad2e6 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMarkSweepCompactAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMarkSweepCompactAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Serial"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:MaxNewSize=10M -Xmx64M -XX:+UseSerialGC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestMarkSweepCompactAllocationPendingStackTrace
+ * @run main/othervm -XX:MaxNewSize=10M -Xmx64M -XX:+UseSerialGC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestMarkSweepCompactAllocationPendingStackTrace
  */
 public class TestMarkSweepCompactAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceG1GCAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceG1GCAllocationPendingStackTrace.java
index 81cf4191c6e..c74eeefa793 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceG1GCAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceG1GCAllocationPendingStackTrace.java
@@ -28,9 +28,10 @@
  *
  * @requires vm.gc == "null" | vm.gc == "G1"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseG1GC -Xlog:gc* -XX:MaxMetaspaceSize=64M jdk.jfr.event.gc.stacktrace.TestMetaspaceG1GCAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseG1GC -Xlog:gc* -XX:MaxMetaspaceSize=64M
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestMetaspaceG1GCAllocationPendingStackTrace
  */
-
 public class TestMetaspaceG1GCAllocationPendingStackTrace {
 
     public static void main(String[] args) throws Exception {
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceParallelGCAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceParallelGCAllocationPendingStackTrace.java
index ab31fe644bf..cc669024015 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceParallelGCAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceParallelGCAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Parallel"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseParallelGC -Xlog:gc* -XX:MaxMetaspaceSize=64M jdk.jfr.event.gc.stacktrace.TestMetaspaceParallelGCAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseParallelGC -Xlog:gc* -XX:MaxMetaspaceSize=64M
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestMetaspaceParallelGCAllocationPendingStackTrace
  */
 public class TestMetaspaceParallelGCAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceSerialGCAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceSerialGCAllocationPendingStackTrace.java
index 83aa4fb522e..7f0ce364b6a 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceSerialGCAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestMetaspaceSerialGCAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Serial"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseSerialGC -Xlog:gc* -XX:MaxMetaspaceSize=64M jdk.jfr.event.gc.stacktrace.TestMetaspaceSerialGCAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseSerialGC -Xlog:gc* -XX:MaxMetaspaceSize=64M
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestMetaspaceSerialGCAllocationPendingStackTrace
  */
 public class TestMetaspaceSerialGCAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelMarkSweepAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelMarkSweepAllocationPendingStackTrace.java
index 5ab67d2561a..ebd1efccfee 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelMarkSweepAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelMarkSweepAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Parallel"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:MaxNewSize=10M -Xmx64M -XX:+UseParallelGC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestParallelMarkSweepAllocationPendingStackTrace
+ * @run main/othervm -XX:MaxNewSize=10M -Xmx64M -XX:+UseParallelGC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestParallelMarkSweepAllocationPendingStackTrace
  */
 public class TestParallelMarkSweepAllocationPendingStackTrace {
 
diff --git a/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelScavengeAllocationPendingStackTrace.java b/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelScavengeAllocationPendingStackTrace.java
index 08ec7ffd05c..6dbbc16e283 100644
--- a/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelScavengeAllocationPendingStackTrace.java
+++ b/test/jdk/jdk/jfr/event/gc/stacktrace/TestParallelScavengeAllocationPendingStackTrace.java
@@ -29,7 +29,9 @@
  *
  * @requires vm.gc == "null" | vm.gc == "Parallel"
  * @library /test/lib /test/jdk
- * @run main/othervm -XX:+UseParallelGC -Xlog:gc* jdk.jfr.event.gc.stacktrace.TestParallelScavengeAllocationPendingStackTrace
+ * @run main/othervm -XX:+UseParallelGC -Xlog:gc*
+ *                   -XX:FlightRecorderOptions:stackdepth=256
+ *                   jdk.jfr.event.gc.stacktrace.TestParallelScavengeAllocationPendingStackTrace
  */
 public class TestParallelScavengeAllocationPendingStackTrace {
 
diff --git a/test/jdk/sun/security/util/DerInputBuffer/B8336667/PoC.java b/test/jdk/sun/security/util/DerInputBuffer/B8336667/PoC.java
new file mode 100644
index 00000000000..d14c213f7b2
--- /dev/null
+++ b/test/jdk/sun/security/util/DerInputBuffer/B8336667/PoC.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8336667
+ * @summary Ensure the unused bytes are calculated correctly when converting
+ *          indefinite length BER to DER
+ * @modules java.base/sun.security.util
+ * @library /test/lib
+ */
+import jdk.test.lib.Asserts;
+import sun.security.util.DerInputStream;
+
+import java.util.HexFormat;
+
+public class PoC {
+    public static void main(String[] args) throws Exception {
+        // A BER indefinite encoding with some unused bytes at the end
+        var data = HexFormat.of().parseHex("""
+                2480 0401AA 0401BB 0000 -- 2 byte string
+                010100 -- boolean false
+                12345678 -- 4 unused bytes"""
+                .replaceAll("(\\s|--.*)", ""));
+        var dis = new DerInputStream(data, 0, data.length - 4, true);
+        Asserts.assertEQ(dis.getDerValue().getOctetString().length, 2);
+        Asserts.assertFalse(dis.getDerValue().getBoolean());
+        dis.atEnd();
+    }
+}
diff --git a/test/jdk/sun/security/util/DerInputBuffer/B8336667/Reproducer.java b/test/jdk/sun/security/util/DerInputBuffer/B8336667/Reproducer.java
new file mode 100644
index 00000000000..f1e458035ee
--- /dev/null
+++ b/test/jdk/sun/security/util/DerInputBuffer/B8336667/Reproducer.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8336667
+ * @summary Ensure the unused bytes are calculated correctly when converting
+ *          indefinite length BER to DER
+ */
+import java.io.ByteArrayInputStream;
+import java.security.cert.CRLException;
+import java.security.cert.CertificateException;
+import java.util.Base64;
+
+public class Reproducer {
+    private static final String INPUT = """
+            MIIBljCCAVMwgAaB/////////yb////////////////////9////AgDv////////////////////
+            /////2RjPWNvbf////8k/////////yb///////////////////9vbf////8k/////////yb/////
+            ////////////////////AgD/////////////b23/////JP////////8m/////yf/////////////
+            /////wIA//////////////////////////////////////8AAABl//////8m/////////y1CRUdJ
+            TiA9Y290cnVlVlZWVlZWVlZWVjEAAAAAAAAArQdVUwNVBAsTA0RvRDEaMBhAA1UAAAAAAAAAAAAA
+            AAAAAAAAAAAAAAAAAAEXDTAzMDcxNTE2MjAwNFqgHzAdMA8GA1UdHAEB/wQFMAPyAf8wCgYDVR0P
+            BAMCAQIwCwYHKoZIzjgEAwUAAzBkARkTA2NvbTEYMBYGCgmSJomT8ixkARkTCG15VGVzdENBMBIC
+            AQHyAjZG+RfHdO4=""";
+
+    Reproducer(byte[] data) {
+        try {
+            java.security.cert.CertificateFactory.
+                    getInstance("X.509").generateCRLs(new ByteArrayInputStream(data));
+        } catch (CertificateException | CRLException e) {
+            if (System.getProperty("dbg", "false").equals("true")) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    public static void main(String[] a) throws Exception {
+        byte[] decodedBytes = Base64.getMimeDecoder().decode(INPUT);
+        new Reproducer(decodedBytes);
+    }
+}
diff --git a/test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java b/test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java
new file mode 100644
index 00000000000..f462ea1a52b
--- /dev/null
+++ b/test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2024, Red Hat Inc.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8334492
+ * @summary Test to verify jcmd accepts %p in output filenames and substitutes for PID
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.management
+ * @run driver TestJcmdPIDSubstitution
+ *
+ */
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.process.ProcessTools;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class TestJcmdPIDSubstitution {
+
+    private static final String FILENAME = "myfile%p";
+
+    public static void main(String[] args) throws Exception {
+        verifyOutputFilenames("Thread.dump_to_file", FILENAME);
+        verifyOutputFilenames("GC.heap_dump", FILENAME);
+        verifyOutputFilenames("Compiler.perfmap", FILENAME);
+        verifyOutputFilenames("System.dump_map", "-F=%s".formatted(FILENAME));
+    }
+
+    private static void verifyOutputFilenames(String... args) throws Exception {
+        long pid = ProcessTools.getProcessId();
+        String test_dir = System.getProperty("test.dir", ".");
+        Path path = Paths.get("%s/myfile%d".formatted(test_dir, pid));
+        OutputAnalyzer output = JcmdBase.jcmd(args);
+        output.shouldHaveExitValue(0);
+        if (Files.exists(path)) {
+            Files.delete(path);
+        } else {
+            throw new Exception("File %s was not created as expected for diagnostic cmd %s".formatted(path, args[0]));
+        }
+    }
+}
diff --git a/test/jdk/tools/jpackage/apps/ChildProcessAppLauncher.java b/test/jdk/tools/jpackage/apps/ChildProcessAppLauncher.java
index 11be90bc456..b599488b563 100644
--- a/test/jdk/tools/jpackage/apps/ChildProcessAppLauncher.java
+++ b/test/jdk/tools/jpackage/apps/ChildProcessAppLauncher.java
@@ -26,12 +26,17 @@
 import java.nio.file.Path;
 
 public class ChildProcessAppLauncher {
-
-    public static void main(String[] args) throws IOException {
-            String calcPath = Path.of(System.getenv("SystemRoot"), "system32", "calc.exe").toString();
-            ProcessBuilder processBuilder = new ProcessBuilder(calcPath);
+    public static void main(String[] args) throws IOException, InterruptedException {
+        if (args.length == 1 && "noexit".equals(args[0])) {
+            var lock = new Object();
+            synchronized (lock) {
+                lock.wait();
+            }
+        } else {
+            var childPath = System.getProperty("jpackage.app-path"); // get the path to the current jpackage app launcher
+            ProcessBuilder processBuilder = new ProcessBuilder(childPath, "noexit"); //ChildProcessAppLauncher acts as third party app
             Process process = processBuilder.start();
-            System.out.println("Calc id=" + process.pid());
-            System.exit(0);
+            System.out.println("Child id=" + process.pid());
+        }
     }
 }
diff --git a/test/jdk/tools/jpackage/windows/WinChildProcessTest.java b/test/jdk/tools/jpackage/windows/WinChildProcessTest.java
index 2928f7f1c5f..4fa7581d2b5 100644
--- a/test/jdk/tools/jpackage/windows/WinChildProcessTest.java
+++ b/test/jdk/tools/jpackage/windows/WinChildProcessTest.java
@@ -53,7 +53,7 @@ public class WinChildProcessTest {
 
     @Test
     public static void test() throws Throwable {
-        long calcPid = 0;
+        long childPid = 0;
         try {
             JPackageCommand cmd = JPackageCommand
                     .helloAppImage(TEST_APP_JAVA + "*Hello");
@@ -68,21 +68,20 @@ public static void test() throws Throwable {
                     .execute(0).getOutput();
             String pidStr = output.get(0);
 
-            // parse calculator PID
-            calcPid = Long.parseLong(pidStr.split("=", 2)[1]);
+            // parse child PID
+            childPid = Long.parseLong(pidStr.split("=", 2)[1]);
 
             // Check whether the termination of third party application launcher
             // also terminating the launched third party application
             // If third party application is not terminated the test is
             // successful else failure
-            Optional<ProcessHandle> processHandle = ProcessHandle.of(calcPid);
+            Optional<ProcessHandle> processHandle = ProcessHandle.of(childPid);
             boolean isAlive = processHandle.isPresent()
                     && processHandle.get().isAlive();
-            System.out.println("Is Alive " + isAlive);
-            TKit.assertTrue(isAlive, "Check is calculator process is alive");
+            TKit.assertTrue(isAlive, "Check is child process is alive");
         } finally {
-            // Kill only a specific calculator instance
-            Runtime.getRuntime().exec("taskkill /F /PID " + calcPid);
+            // Kill only a specific child instance
+            Runtime.getRuntime().exec("taskkill /F /PID " + childPid);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/test/langtools/jdk/javadoc/doclet/testErasure/TestErasure.java b/test/langtools/jdk/javadoc/doclet/testErasure/TestErasure.java
index 3c9f9b6fd9d..f80074c50e2 100644
--- a/test/langtools/jdk/javadoc/doclet/testErasure/TestErasure.java
+++ b/test/langtools/jdk/javadoc/doclet/testErasure/TestErasure.java
@@ -82,15 +82,19 @@ class Y { }
                 <section class="constructor-summary" id="constructor-summary">
                 <h2>Constructor Summary</h2>
                 <div class="caption"><span>Constructors</span></div>
-                <div class="summary-table two-column-summary">
-                <div class="table-header col-first">Constructor</div>
+                <div class="summary-table three-column-summary">
+                <div class="table-header col-first">Modifier</div>
+                <div class="table-header col-second">Constructor</div>
                 <div class="table-header col-last">Description</div>
+                <div class="col-first even-row-color"><code>&nbsp;</code></div>
                 <div class="col-constructor-name even-row-color"><code>\
                 <a href="#%3Cinit%3E(T)" class="member-name-link">Foo</a><wbr>(T&nbsp;arg)</code></div>
                 <div class="col-last even-row-color">&nbsp;</div>
+                <div class="col-first odd-row-color"><code>&nbsp;&lt;T extends X&gt;<br></code></div>
                 <div class="col-constructor-name odd-row-color"><code>\
                 <a href="#%3Cinit%3E(X)" class="member-name-link">Foo</a><wbr>(T&nbsp;arg)</code></div>
                 <div class="col-last odd-row-color">&nbsp;</div>
+                <div class="col-first even-row-color"><code>&nbsp;&lt;T extends Y&gt;<br></code></div>
                 <div class="col-constructor-name even-row-color"><code>\
                 <a href="#%3Cinit%3E(Y)" class="member-name-link">Foo</a><wbr>(T&nbsp;arg)</code></div>
                 <div class="col-last even-row-color">&nbsp;</div>
@@ -188,13 +192,16 @@ class X { }
                 <section class="constructor-summary" id="constructor-summary">
                 <h2>Constructor Summary</h2>
                 <div class="caption"><span>Constructors</span></div>
-                <div class="summary-table two-column-summary">
-                <div class="table-header col-first">Constructor</div>
+                <div class="summary-table three-column-summary">
+                <div class="table-header col-first">Modifier</div>
+                <div class="table-header col-second">Constructor</div>
                 <div class="table-header col-last">Description</div>
+                <div class="col-first even-row-color"><code>&nbsp;</code></div>
                 <div class="col-constructor-name even-row-color"><code>\
                 <a href="#%3Cinit%3E(T)" class="member-name-link">Foo</a>\
                 <wbr>(<a href="Foo.html" title="type parameter in Foo">T</a>&nbsp;arg)</code></div>
                 <div class="col-last even-row-color">&nbsp;</div>
+                <div class="col-first odd-row-color"><code>&nbsp;&lt;T extends X&gt;<br></code></div>
                 <div class="col-constructor-name odd-row-color"><code>\
                 <a href="#%3Cinit%3E(X)" class="member-name-link">Foo</a><wbr>(T&nbsp;arg)</code></div>
                 <div class="col-last odd-row-color">&nbsp;</div>
diff --git a/test/langtools/jdk/javadoc/doclet/testTypeParams/TestTypeParameters.java b/test/langtools/jdk/javadoc/doclet/testTypeParams/TestTypeParameters.java
index 7f586b3539d..0d95ee38cdc 100644
--- a/test/langtools/jdk/javadoc/doclet/testTypeParams/TestTypeParameters.java
+++ b/test/langtools/jdk/javadoc/doclet/testTypeParams/TestTypeParameters.java
@@ -23,12 +23,13 @@
 
 /*
  * @test
- * @bug      4927167 4974929 7010344 8025633 8081854 8182765 8187288 8261976
+ * @bug      4927167 4974929 6381729 7010344 8025633 8081854 8182765 8187288 8261976
  * @summary  When the type parameters are more than 10 characters in length,
  *           make sure there is a line break between type params and return type
  *           in member summary. Also, test for type parameter links in package-summary and
  *           class-use pages. The class/annotation pages should check for type
  *           parameter links in the class/annotation signature section when -linksource is set.
+ *           Verify that generic type parameters on constructors are documented.
  * @library  ../../lib
  * @modules jdk.javadoc/jdk.javadoc.internal.tool
  * @build    javadoc.tester.*
@@ -94,4 +95,25 @@ public class </span><span class="element-name"><a href="../src-html/pkg/ClassUse
                     le="class in pkg">ParamTest2</a>&lt;java.util.List&lt;? extends <a href="Foo4.ht\
                     ml" title="class in pkg">Foo4</a>&gt;&gt;&gt;""");
     }
+
+    @Test
+    public void test3() {
+        javadoc("-d", "out-3",
+                "-Xdoclint:none",
+                "--no-platform-links",
+                "-sourcepath", testSrc,
+                "pkg");
+        checkExit(Exit.OK);
+
+        checkOutput("pkg/CtorTypeParam.html", true,
+                """
+                    <div class="col-first even-row-color"><code>&nbsp;&lt;T extends java.lang.Runnable&gt;<br></code></div>
+                    <div class="col-constructor-name even-row-color"><code>\
+                    <a href="#%3Cinit%3E()" class="member-name-link">CtorTypeParam</a>()</code></div>
+                    <div class="col-last even-row-color">&nbsp;</div>""",
+                """
+                    <div class="member-signature"><span class="modifiers">public</span>\
+                    &nbsp;<span class="type-parameters">&lt;T extends java.lang.Runnable&gt;</span>\
+                    &nbsp;<span class="element-name">CtorTypeParam</span>()</div>""");
+    }
 }
diff --git a/src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.hpp b/test/langtools/jdk/javadoc/doclet/testTypeParams/pkg/CtorTypeParam.java
similarity index 60%
rename from src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.hpp
rename to test/langtools/jdk/javadoc/doclet/testTypeParams/pkg/CtorTypeParam.java
index c20c483c77d..a7f2309475d 100644
--- a/src/hotspot/share/gc/shenandoah/mode/shenandoahIUMode.hpp
+++ b/test/langtools/jdk/javadoc/doclet/testTypeParams/pkg/CtorTypeParam.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -19,24 +19,11 @@
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
- *
  */
 
-#ifndef SHARE_GC_SHENANDOAH_MODE_SHENANDOAHIUMODE_HPP
-#define SHARE_GC_SHENANDOAH_MODE_SHENANDOAHIUMODE_HPP
-
-#include "gc/shenandoah/mode/shenandoahMode.hpp"
-
-class ShenandoahHeuristics;
-
-class ShenandoahIUMode : public ShenandoahMode {
-public:
-  virtual void initialize_flags() const;
-  virtual ShenandoahHeuristics* initialize_heuristics() const;
-
-  virtual const char* name()     { return "Incremental-Update (IU)"; }
-  virtual bool is_diagnostic()   { return false; }
-  virtual bool is_experimental() { return true; }
-};
+package pkg;
 
-#endif // SHARE_GC_SHENANDOAH_MODE_SHENANDOAHIUMODE_HPP
+public class CtorTypeParam {
+    public <T extends Runnable> CtorTypeParam() {
+    }
+}
diff --git a/test/langtools/tools/javac/annotations/repeatingAnnotations/CompletionErrorOnRepeatingAnnosTest.java b/test/langtools/tools/javac/annotations/repeatingAnnotations/CompletionErrorOnRepeatingAnnosTest.java
new file mode 100644
index 00000000000..b075a510155
--- /dev/null
+++ b/test/langtools/tools/javac/annotations/repeatingAnnotations/CompletionErrorOnRepeatingAnnosTest.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8332850
+ * @summary javac crashes if container for repeatable annotation is not found
+ * @library /tools/javac/lib /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ */
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.List;
+
+import toolbox.*;
+import toolbox.Task.*;
+
+public class CompletionErrorOnRepeatingAnnosTest {
+    ToolBox tb = new ToolBox();
+
+    public static void main(String... args) throws Exception {
+        CompletionErrorOnRepeatingAnnosTest t = new CompletionErrorOnRepeatingAnnosTest();
+        //t.testMissingContainerAnno();
+        t.testMissingContainerTypeAnno();
+    }
+
+    void testMissingContainerTypeAnno() throws Exception {
+        doTest(
+                """
+                import java.lang.annotation.*;
+                import static java.lang.annotation.RetentionPolicy.*;
+                import static java.lang.annotation.ElementType.*;
+                @Target({TYPE_USE,FIELD}) @Repeatable( As.class) @interface A { }
+                @Target({TYPE_USE,FIELD}) @interface As { A[] value(); }
+                """,
+                """
+                class T {
+                    @A @A String data = "test";
+                }
+                """,
+                List.of(
+                        "T.java:2:5: compiler.err.cant.access: As, (compiler.misc.class.file.not.found: As)",
+                        "T.java:2:8: compiler.err.invalid.repeatable.annotation.no.value: As",
+                        "2 errors"
+                )
+        );
+    }
+
+    void testMissingContainerAnno() throws Exception {
+        doTest(
+                """
+                import java.lang.annotation.Repeatable;
+                @Repeatable(As.class)
+                @interface A {}
+                @interface As {
+                    A[] value();
+                }
+                """,
+                "@A @A class T {}",
+                List.of(
+                        "T.java:1:1: compiler.err.cant.access: As, (compiler.misc.class.file.not.found: As)",
+                        "T.java:1:4: compiler.err.invalid.repeatable.annotation.no.value: As",
+                        "2 errors"
+                )
+        );
+    }
+
+    private void doTest(String annosSrc, String annotatedSrc, List<String> expectedOutput) throws Exception {
+        Path base = Paths.get(".");
+        Path src = base.resolve("src");
+        tb.createDirectories(src);
+        tb.writeJavaFiles(src, annosSrc);
+        Path out = base.resolve("out");
+        tb.createDirectories(out);
+        new JavacTask(tb)
+                .outdir(out)
+                .files(tb.findJavaFiles(src))
+                .run();
+        // let's now compile T.java which uses repeated annotations, we want to load the anno classes from the CP
+        tb.deleteFiles(src.resolve("A.java"));
+        tb.writeJavaFiles(src, annotatedSrc);
+        new JavacTask(tb)
+                .outdir(out)
+                .classpath(out)
+                .files(tb.findJavaFiles(src))
+                .run();
+        // now if we remove As.class there will be an error but javac should not crash
+        tb.deleteFiles(out.resolve("As.class"));
+        List<String> log = new JavacTask(tb)
+                .outdir(out)
+                .classpath(out)
+                .options("-XDrawDiagnostics")
+                .files(tb.findJavaFiles(src))
+                .run(Expect.FAIL)
+                .writeAll()
+                .getOutputLines(Task.OutputKind.DIRECT);
+
+        if (!expectedOutput.equals(log))
+            throw new Exception("expected output not found: " + log);
+    }
+}
diff --git a/test/jdk/java/lang/Thread/virtual/ThreadBuilders.java b/test/lib/jdk/test/lib/thread/VThreadScheduler.java
similarity index 63%
rename from test/jdk/java/lang/Thread/virtual/ThreadBuilders.java
rename to test/lib/jdk/test/lib/thread/VThreadScheduler.java
index a6a5d6abdbc..46b75fbe5eb 100644
--- a/test/jdk/java/lang/Thread/virtual/ThreadBuilders.java
+++ b/test/lib/jdk/test/lib/thread/VThreadScheduler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -21,28 +21,50 @@
  * questions.
  */
 
+package jdk.test.lib.thread;
+
 import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
 
 /**
- * Helper class for creating Thread buidlers.
+ * Helper class to allow tests run virtual threads with a custom scheduler.
  *
  * Tests using this class need to open java.base/java.lang.
  */
-class ThreadBuilders {
-    private ThreadBuilders() { }
+public class VThreadScheduler {
+    private VThreadScheduler() { }
 
-    private static final Constructor<?> VTBUILDER_CTOR;
-    static {
+    /**
+     * Returns the scheduler for the given virtual thread.
+     */
+    public static Executor scheduler(Thread thread) {
+        if (!thread.isVirtual())
+            throw new IllegalArgumentException("Not a virtual thread");
         try {
-            Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
-            Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
-            ctor.setAccessible(true);
-            VTBUILDER_CTOR = ctor;
+            Field scheduler = Class.forName("java.lang.VirtualThread")
+                    .getDeclaredField("scheduler");
+            scheduler.setAccessible(true);
+            return (Executor) scheduler.get(thread);
         } catch (Exception e) {
-            throw new InternalError(e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Return true if custom schedulers are supported.
+     */
+    public static boolean supportsCustomScheduler() {
+        try (var pool = Executors.newCachedThreadPool()) {
+            try {
+                virtualThreadBuilder(pool);
+                return true;
+            } catch (UnsupportedOperationException e) {
+                return false;
+            }
         }
     }
 
@@ -50,9 +72,12 @@ private ThreadBuilders() { }
      * Returns a builder to create virtual threads that use the given scheduler.
      * @throws UnsupportedOperationException if custom schedulers are not supported
      */
-    static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
+    public static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
         try {
-            return (Thread.Builder.OfVirtual) VTBUILDER_CTOR.newInstance(scheduler);
+            Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
+            Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
+            ctor.setAccessible(true);
+            return (Thread.Builder.OfVirtual) ctor.newInstance(scheduler);
         } catch (InvocationTargetException e) {
             Throwable cause = e.getCause();
             if (cause instanceof RuntimeException re) {
@@ -65,16 +90,10 @@ static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
     }
 
     /**
-     * Return true if custom schedulers are supported.
+     * Returns a ThreadFactory to create virtual threads that use the given scheduler.
+     * @throws UnsupportedOperationException if custom schedulers are not supported
      */
-    static boolean supportsCustomScheduler() {
-        try (var pool = Executors.newCachedThreadPool()) {
-            try {
-                virtualThreadBuilder(pool);
-                return true;
-            } catch (UnsupportedOperationException e) {
-                return false;
-            }
-        }
+    public static ThreadFactory virtualThreadFactory(Executor scheduler) {
+        return virtualThreadBuilder(scheduler).factory();
     }
 }
diff --git a/test/lib/jdk/test/whitebox/parser/DiagnosticCommand.java b/test/lib/jdk/test/whitebox/parser/DiagnosticCommand.java
index adb699bac6a..6b7efa2dc87 100644
--- a/test/lib/jdk/test/whitebox/parser/DiagnosticCommand.java
+++ b/test/lib/jdk/test/whitebox/parser/DiagnosticCommand.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,7 +26,7 @@
 public class DiagnosticCommand {
 
     public enum DiagnosticArgumentType {
-        JLONG, BOOLEAN, STRING, NANOTIME, STRINGARRAY, MEMORYSIZE
+        JLONG, BOOLEAN, STRING, NANOTIME, STRINGARRAY, MEMORYSIZE, FILE
     }
 
     private String name;
diff --git a/test/micro/org/openjdk/bench/jdk/classfile/Write.java b/test/micro/org/openjdk/bench/jdk/classfile/Write.java
index 59d07b05927..e5304f0e51c 100644
--- a/test/micro/org/openjdk/bench/jdk/classfile/Write.java
+++ b/test/micro/org/openjdk/bench/jdk/classfile/Write.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,7 +22,6 @@
  */
 package org.openjdk.bench.jdk.classfile;
 
-import java.lang.classfile.AccessFlags;
 import java.lang.reflect.AccessFlag;
 import java.lang.classfile.ClassFile;
 import java.lang.classfile.TypeKind;
@@ -30,6 +29,8 @@
 import jdk.internal.org.objectweb.asm.*;
 import org.openjdk.jmh.annotations.*;
 import java.io.FileOutputStream;
+import static java.lang.classfile.ClassFile.ACC_PUBLIC;
+import static java.lang.classfile.ClassFile.ACC_STATIC;
 import static java.lang.constant.ConstantDescs.*;
 
 import java.nio.file.Files;
@@ -148,7 +149,7 @@ public byte[] jdkTree() {
               );
             for (int xi = 0; xi < 40; ++xi) {
                 cb.withMethod("main" + ((xi == 0) ? "" : "" + xi), MTD_void_StringArray,
-                              AccessFlags.ofMethod(AccessFlag.STATIC, AccessFlag.PUBLIC).flagsMask(),
+                              ACC_PUBLIC | ACC_STATIC,
                               mb -> mb.withCode(c0 -> {
                                   java.lang.classfile.Label loopTop = c0.newLabel();
                                   java.lang.classfile.Label loopEnd = c0.newLabel();
@@ -196,7 +197,7 @@ public byte[] jdkTreePrimitive() {
               );
             for (int xi = 0; xi < 40; ++xi) {
                 cb.withMethod("main" + ((xi == 0) ? "" : "" + xi), MTD_void_StringArray,
-                              AccessFlags.ofMethod(AccessFlag.STATIC, AccessFlag.PUBLIC).flagsMask(),
+                              ACC_PUBLIC | ACC_STATIC,
                               mb -> mb.withCode(c0 -> {
                                   java.lang.classfile.Label loopTop = c0.newLabel();
                                   java.lang.classfile.Label loopEnd = c0.newLabel();
diff --git a/test/micro/org/openjdk/bench/vm/compiler/MergeStoreBench.java b/test/micro/org/openjdk/bench/vm/compiler/MergeStoreBench.java
new file mode 100644
index 00000000000..26c8287c4de
--- /dev/null
+++ b/test/micro/org/openjdk/bench/vm/compiler/MergeStoreBench.java
@@ -0,0 +1,1132 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.vm.compiler;
+
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
+import java.lang.reflect.Field;
+import java.nio.ByteOrder;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+import jdk.internal.misc.Unsafe;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@State(Scope.Thread)
+@Warmup(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
+@Measurement(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
+@Fork(value = 3, jvmArgsAppend = {"--add-exports", "java.base/jdk.internal.misc=ALL-UNNAMED"})
+public class MergeStoreBench {
+    private static final Unsafe UNSAFE = Unsafe.getUnsafe();
+
+    final static VarHandle INT_L  = MethodHandles.byteArrayViewVarHandle(int[].class , ByteOrder.LITTLE_ENDIAN);
+    final static VarHandle INT_B  = MethodHandles.byteArrayViewVarHandle(int[].class , ByteOrder.BIG_ENDIAN);
+    final static VarHandle LONG_L = MethodHandles.byteArrayViewVarHandle(long[].class, ByteOrder.LITTLE_ENDIAN);
+    final static VarHandle LONG_B = MethodHandles.byteArrayViewVarHandle(long[].class, ByteOrder.BIG_ENDIAN);
+    final static VarHandle CHAR_L = MethodHandles.byteArrayViewVarHandle(char[].class, ByteOrder.LITTLE_ENDIAN);
+    final static VarHandle CHAR_B = MethodHandles.byteArrayViewVarHandle(char[].class, ByteOrder.BIG_ENDIAN);
+
+    final static int NUMBERS = 8192;
+
+    final byte[] bytes4 = new byte[NUMBERS * 4];
+    final byte[] bytes8 = new byte[NUMBERS * 8];
+    final int [] ints   = new int [NUMBERS    ];
+    final long[] longs  = new long[NUMBERS    ];
+    final char[] chars  = new char[NUMBERS    ];
+
+    @Setup
+    public void setup() {
+        Random r = new Random();
+        for (int i = 0; i < ints.length; i++) {
+            ints[i] = r.nextInt();
+            INT_L.set(bytes4, i * 4, i);
+        }
+
+        for (int i = 0; i < longs.length; i++) {
+            longs[i] = r.nextLong();
+            LONG_L.set(bytes8, i * 8, i);
+        }
+    }
+
+    /*
+     * The names of these cases have the following `B/L/V/U` suffixes, which are:
+     * ```
+     * B BigEndian
+     * L LittleEndian
+     * V VarHandle
+     * U Unsafe
+     * R ReverseBytes
+     * C Unsafe.getChar & putChar
+     * S Unsafe.getShort & putShort
+     * ```
+     */
+
+    @Benchmark
+    public void getIntB(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntB(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntBU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntBU(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntBV(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += (int) INT_B.get(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntL(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntL(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntLU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntLU(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntLV(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += (int) INT_L.get(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntRB(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntRB(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntRBU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntRBU(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntRL(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntRL(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntRLU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += getIntRLU(bytes4, i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntRU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += Integer.reverseBytes(
+                    UNSAFE.getInt(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 4));
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getIntU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += UNSAFE.getInt(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 4);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntB(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntB(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntBU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntBU(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntBV(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            INT_B.set(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntL(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntL(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntLU(Blackhole BH) {
+        int sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntLU(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntLV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            INT_L.set(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntRB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntRB(bytes4, i * 4, ints[i]);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntRBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntRBU(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntRL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntRL(bytes4, i * 4, ints[i]);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntRLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            setIntRLU(bytes4, i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntRU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            v = Integer.reverseBytes(v);
+            UNSAFE.putInt(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setIntU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            int v = ints[i];
+            UNSAFE.putInt(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 4, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongB(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongBU(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongBV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += (long) LONG_B.get(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongL(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongLU(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongLV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < ints.length; i++) {
+            sum += (long) LONG_L.get(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongRB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongRB(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongRBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongRBU(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongRL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongRL(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongRLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += getLongRLU(bytes8, i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongRU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += Long.reverseBytes(
+                    UNSAFE.getLong(bytes8, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 8));
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getLongU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            sum += UNSAFE.getLong(bytes8, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 8);
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongB(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongBU(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongBV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            LONG_B.set(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongL(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongLU(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongLV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            LONG_L.set(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongRB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongRB(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongRBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongRBU(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongRL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongRL(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongRLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            setLongRLU(bytes8, i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongRU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            v = Long.reverseBytes(v);
+            UNSAFE.putLong(bytes8, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setLongU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            long v = longs[i];
+            UNSAFE.putLong(bytes8, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 8, v);
+            sum += v;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getCharB(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = getCharB(bytes4, i);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getCharBV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = (char) CHAR_B.get(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 2);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getCharBU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = getCharBU(bytes4, i);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getCharL(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = getCharL(bytes4, i);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+    @Benchmark
+    public void getCharLU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = getCharLU(bytes4, i);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+
+    @Benchmark
+    public void getCharLV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = (char) CHAR_L.get(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 2);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void getCharC(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            char c = UNSAFE.getChar(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 2);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setCharBS(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < chars.length; i++) {
+            char c = chars[i];
+            putShortB(bytes4, i * 2, c);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setCharBV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < chars.length; i++) {
+            char c = chars[i];
+            CHAR_B.set(bytes4, i * 2, c);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setCharLS(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < chars.length; i++) {
+            char c = chars[i];
+            putShortL(bytes4, i * 2, c);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setCharLV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < chars.length; i++) {
+            char c = chars[i];
+            CHAR_L.set(bytes4, i * 2, c);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void setCharC(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < chars.length; i++) {
+            char c = chars[i];
+            UNSAFE.putChar(bytes4, Unsafe.ARRAY_BYTE_BASE_OFFSET + i * 2, c);
+            sum += c;
+        }
+        BH.consume(sum);
+    }
+
+    /*
+     * putChars4 Test whether four constant chars can be MergeStored
+     *
+     */
+    @Benchmark
+    public void putChars4B(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4B(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4BU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4BU(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4BV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4BV(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4L(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4L(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4LU(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4LU(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4LV(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4LV(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4C(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4C(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    @Benchmark
+    public void putChars4S(Blackhole BH) {
+        long sum = 0;
+        for (int i = 0; i < longs.length; i++) {
+            putChars4S(bytes8, i * 4);
+            sum += longs[i];
+        }
+        BH.consume(sum);
+    }
+
+    static int getIntB(byte[] array, int offset) {
+        return ((array[offset    ] & 0xff) << 24)
+             | ((array[offset + 1] & 0xff) << 16)
+             | ((array[offset + 2] & 0xff) <<  8)
+             | ((array[offset + 3] & 0xff)      );
+    }
+
+    static int getIntBU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        return ((UNSAFE.getByte(array, address    ) & 0xff) << 24)
+             | ((UNSAFE.getByte(array, address + 1) & 0xff) << 16)
+             | ((UNSAFE.getByte(array, address + 2) & 0xff) <<  8)
+             | ((UNSAFE.getByte(array, address + 3) & 0xff)      );
+    }
+
+    static int getIntL(byte[] array, int offset) {
+        return ((array[offset       ] & 0xff)      )
+                | ((array[offset + 1] & 0xff) <<  8)
+                | ((array[offset + 2] & 0xff) << 16)
+                | ((array[offset + 3] & 0xff) << 24);
+    }
+
+    static int getIntRB(byte[] array, int offset) {
+        return Integer.reverseBytes(getIntB(array, offset));
+    }
+
+    static int getIntRBU(byte[] array, int offset) {
+        return Integer.reverseBytes(getIntBU(array, offset));
+    }
+
+    static int getIntRL(byte[] array, int offset) {
+        return Integer.reverseBytes(getIntL(array, offset));
+    }
+
+    static int getIntRLU(byte[] array, int offset) {
+        return Integer.reverseBytes(getIntLU(array, offset));
+    }
+
+    static void setIntB(byte[] array, int offset, int value) {
+        array[offset    ] = (byte) (value >> 24);
+        array[offset + 1] = (byte) (value >> 16);
+        array[offset + 2] = (byte) (value >>  8);
+        array[offset + 3] = (byte) (value      );
+    }
+
+    static void setIntBU(byte[] array, int offset, int value) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        UNSAFE.putByte(array, address    , (byte) (value >> 24));
+        UNSAFE.putByte(array, address + 1, (byte) (value >> 16));
+        UNSAFE.putByte(array, address + 2, (byte) (value >>  8));
+        UNSAFE.putByte(array, address + 3, (byte) (value      ));
+    }
+
+    public static void setIntL(byte[] array, int offset, int value) {
+        array[offset    ] = (byte)  value;
+        array[offset + 1] = (byte) (value >> 8);
+        array[offset + 2] = (byte) (value >> 16);
+        array[offset + 3] = (byte) (value >> 24);
+    }
+
+    public static void setIntLU(byte[] array, int offset, int value) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        UNSAFE.putByte(array, address    , (byte)  value       );
+        UNSAFE.putByte(array, address + 1, (byte) (value >>  8));
+        UNSAFE.putByte(array, address + 2, (byte) (value >> 16));
+        UNSAFE.putByte(array, address + 3, (byte) (value >> 24));
+    }
+
+    public static void setIntRL(byte[] array, int offset, int value) {
+        value = Integer.reverseBytes(value);
+        setIntL(array, offset, value);
+    }
+
+    public static void setIntRLU(byte[] array, int offset, int value) {
+        value = Integer.reverseBytes(value);
+        setIntLU(array, offset, value);
+    }
+
+    public static void setIntRB(byte[] array, int offset, int value) {
+        value = Integer.reverseBytes(value);
+        setIntB(array, offset, value);
+    }
+
+    public static void setIntRBU(byte[] array, int offset, int value) {
+        value = Integer.reverseBytes(value);
+        setIntBU(array, offset, value);
+    }
+
+    static long getLongB(byte[] array, int offset) {
+        return (((long) array[offset    ] & 0xff) << 56)
+             | (((long) array[offset + 1] & 0xff) << 48)
+             | (((long) array[offset + 2] & 0xff) << 40)
+             | (((long) array[offset + 3] & 0xff) << 32)
+             | (((long) array[offset + 4] & 0xff) << 24)
+             | (((long) array[offset + 5] & 0xff) << 16)
+             | (((long) array[offset + 6] & 0xff) << 8)
+             | (((long) array[offset + 7] & 0xff)     );
+    }
+
+    static long getLongBU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        return (((long)(UNSAFE.getByte(array, address)     & 0xff)) << 56)
+             | (((long)(UNSAFE.getByte(array, address + 1) & 0xff)) << 48)
+             | (((long)(UNSAFE.getByte(array, address + 2) & 0xff)) << 40)
+             | (((long)(UNSAFE.getByte(array, address + 3) & 0xff)) << 32)
+             | (((long)(UNSAFE.getByte(array, address + 4) & 0xff)) << 24)
+             | (((long)(UNSAFE.getByte(array, address + 5) & 0xff)) << 16)
+             | (((long)(UNSAFE.getByte(array, address + 6) & 0xff)) <<  8)
+             | (((long)(UNSAFE.getByte(array, address + 7) & 0xff))      );
+    }
+
+    public static long getLongL(byte[] array, int offset) {
+        return (((long) array[offset    ] & 0xff)      )
+             | (((long) array[offset + 1] & 0xff) <<  8)
+             | (((long) array[offset + 2] & 0xff) << 16)
+             | (((long) array[offset + 3] & 0xff) << 24)
+             | (((long) array[offset + 4] & 0xff) << 32)
+             | (((long) array[offset + 5] & 0xff) << 40)
+             | (((long) array[offset + 6] & 0xff) << 48)
+             | (((long) array[offset + 7] & 0xff) << 56);
+    }
+
+    static long getLongLU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        return (((long)(UNSAFE.getByte(array, address    ) & 0xff))      )
+             | (((long)(UNSAFE.getByte(array, address + 1) & 0xff)) <<  8)
+             | (((long)(UNSAFE.getByte(array, address + 2) & 0xff)) << 16)
+             | (((long)(UNSAFE.getByte(array, address + 3) & 0xff)) << 24)
+             | (((long)(UNSAFE.getByte(array, address + 4) & 0xff)) << 32)
+             | (((long)(UNSAFE.getByte(array, address + 5) & 0xff)) << 40)
+             | (((long)(UNSAFE.getByte(array, address + 6) & 0xff)) << 48)
+             | (((long)(UNSAFE.getByte(array, address + 7) & 0xff)) << 56);
+    }
+
+    static long getLongRB(byte[] array, int offset) {
+        return getLongB(array, offset);
+    }
+
+    static long getLongRBU(byte[] array, int offset) {
+        return getLongBU(array, offset);
+    }
+
+    static long getLongRL(byte[] array, int offset) {
+        return getLongL(array, offset);
+    }
+
+    static long getLongRLU(byte[] array, int offset) {
+        return getLongLU(array, offset);
+    }
+
+    static void setLongB(byte[] array, int offset, long value) {
+        array[offset]     = (byte) (value >> 56);
+        array[offset + 1] = (byte) (value >> 48);
+        array[offset + 2] = (byte) (value >> 40);
+        array[offset + 3] = (byte) (value >> 32);
+        array[offset + 4] = (byte) (value >> 24);
+        array[offset + 5] = (byte) (value >> 16);
+        array[offset + 6] = (byte) (value >>  8);
+        array[offset + 7] = (byte) (value      );
+    }
+
+    public static void setLongL(byte[] array, int offset, long value) {
+        array[offset]     = (byte)  value       ;
+        array[offset + 1] = (byte) (value >> 8 );
+        array[offset + 2] = (byte) (value >> 16);
+        array[offset + 3] = (byte) (value >> 24);
+        array[offset + 4] = (byte) (value >> 32);
+        array[offset + 5] = (byte) (value >> 40);
+        array[offset + 6] = (byte) (value >> 48);
+        array[offset + 7] = (byte) (value >> 56);
+    }
+
+    public static void setLongRL(byte[] array, int offset, long value) {
+        value = Long.reverseBytes(value);
+        setLongL(array, offset, value);
+    }
+
+    public static void setLongRLU(byte[] array, int offset, long value) {
+        value = Long.reverseBytes(value);
+        setLongLU(array, offset, value);
+    }
+
+    public static void setLongRB(byte[] array, int offset, long value) {
+        value = Long.reverseBytes(value);
+        setLongB(array, offset, value);
+    }
+
+    public static void setLongRBU(byte[] array, int offset, long value) {
+        value = Long.reverseBytes(value);
+        setLongBU(array, offset, value);
+    }
+
+    public static void setLongBU(byte[] array, int offset, long value) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        UNSAFE.putByte(array, address    , (byte) (value >> 56));
+        UNSAFE.putByte(array, address + 1, (byte) (value >> 48));
+        UNSAFE.putByte(array, address + 2, (byte) (value >> 40));
+        UNSAFE.putByte(array, address + 3, (byte) (value >> 32));
+        UNSAFE.putByte(array, address + 4, (byte) (value >> 24));
+        UNSAFE.putByte(array, address + 5, (byte) (value >> 16));
+        UNSAFE.putByte(array, address + 6, (byte) (value >>  8));
+        UNSAFE.putByte(array, address + 7, (byte)  value       );
+    }
+
+    public static void setLongLU(byte[] array, int offset, long value) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        UNSAFE.putByte(array, address    , (byte)  value       );
+        UNSAFE.putByte(array, address + 1, (byte) (value >>  8));
+        UNSAFE.putByte(array, address + 2, (byte) (value >> 16));
+        UNSAFE.putByte(array, address + 3, (byte) (value >> 24));
+        UNSAFE.putByte(array, address + 4, (byte) (value >> 32));
+        UNSAFE.putByte(array, address + 5, (byte) (value >> 40));
+        UNSAFE.putByte(array, address + 6, (byte) (value >> 48));
+        UNSAFE.putByte(array, address + 7, (byte) (value >> 56));
+    }
+
+    public static int getIntLU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + offset;
+        return ((UNSAFE.getByte(array, address    ) & 0xff)      )
+             | ((UNSAFE.getByte(array, address + 1) & 0xff) <<  8)
+             | ((UNSAFE.getByte(array, address + 2) & 0xff) << 16)
+             | ((UNSAFE.getByte(array, address + 3) & 0xff) << 24);
+    }
+
+    public static char getCharB(byte[] val, int index) {
+        index <<= 1;
+        return (char)(((val[index    ] & 0xff) << 8)
+                    | ((val[index + 1] & 0xff)));
+    }
+
+    public static char getCharBR(byte[] val, int index) {
+        return Character.reverseBytes(getCharB(val, index));
+    }
+
+    public static char getCharL(byte[] val, int index) {
+        index <<= 1;
+        return (char)(((val[index    ] & 0xff))
+                    | ((val[index + 1] & 0xff) << 8));
+    }
+
+    public static char getCharLR(byte[] val, int index) {
+        return Character.reverseBytes(getCharL(val, index));
+    }
+
+    public static char getCharBU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        return (char) (((UNSAFE.getByte(array, address    ) & 0xff) << 8)
+                     | ((UNSAFE.getByte(array, address + 1) & 0xff)     ));
+    }
+
+    public static char getCharLU(byte[] array, int offset) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        return (char) (((UNSAFE.getByte(array, address    ) & 0xff)     )
+                     | ((UNSAFE.getByte(array, address + 1) & 0xff) << 8));
+    }
+
+    public void putChars4B(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        putShortB(bytes, offset    , c0);
+        putShortB(bytes, offset + 1, c1);
+        putShortB(bytes, offset + 2, c2);
+        putShortB(bytes, offset + 3, c3);
+    }
+
+    public void putChars4BU(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        putShortBU(bytes, offset    , c0);
+        putShortBU(bytes, offset + 1, c1);
+        putShortBU(bytes, offset + 2, c2);
+        putShortBU(bytes, offset + 3, c3);
+    }
+
+    public void putChars4BV(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        offset <<= 1;
+        CHAR_B.set(bytes, offset    , c0);
+        CHAR_B.set(bytes, offset + 2, c1);
+        CHAR_B.set(bytes, offset + 4, c2);
+        CHAR_B.set(bytes, offset + 6, c3);
+    }
+
+    public void putChars4L(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        putShortL(bytes, offset    , c0);
+        putShortL(bytes, offset + 1, c1);
+        putShortL(bytes, offset + 2, c2);
+        putShortL(bytes, offset + 3, c3);
+    }
+
+    public void putChars4LV(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        offset <<= 1;
+        CHAR_L.set(bytes, offset    , c0);
+        CHAR_L.set(bytes, offset + 2, c1);
+        CHAR_L.set(bytes, offset + 4, c2);
+        CHAR_L.set(bytes, offset + 6, c3);
+    }
+
+    public void putChars4LU(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        putShortLU(bytes, offset    , c0);
+        putShortLU(bytes, offset + 1, c1);
+        putShortLU(bytes, offset + 2, c2);
+        putShortLU(bytes, offset + 3, c3);
+    }
+
+    public void putChars4C(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        UNSAFE.putChar(bytes, address    , c0);
+        UNSAFE.putChar(bytes, address + 2, c1);
+        UNSAFE.putChar(bytes, address + 4, c2);
+        UNSAFE.putChar(bytes, address + 6, c3);
+    }
+
+    public void putChars4S(byte[] bytes, int offset) {
+        char c0 = 'n', c1 = 'u', c2 = 'l', c3 = 'l';
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        UNSAFE.putShort(bytes, address    , (short) c0);
+        UNSAFE.putShort(bytes, address + 2, (short) c1);
+        UNSAFE.putShort(bytes, address + 4, (short) c2);
+        UNSAFE.putShort(bytes, address + 6, (short) c3);
+    }
+
+    private static void putShortB(byte[] val, int index, int c) {
+        index <<= 1;
+        val[index    ] = (byte)(c >> 8);
+        val[index + 1] = (byte)(c     );
+    }
+
+    public static void putShortBU(byte[] array, int offset, int c) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        UNSAFE.putByte(array, address    , (byte) (c >>  8));
+        UNSAFE.putByte(array, address + 1, (byte) (c      ));
+    }
+
+    private static void putShortL(byte[] val, int index, int c) {
+        index <<= 1;
+        val[index    ] = (byte)(c     );
+        val[index + 1] = (byte)(c >> 8);
+    }
+
+    public static void putShortLU(byte[] array, int offset, int c) {
+        final long address = Unsafe.ARRAY_BYTE_BASE_OFFSET + (offset << 1);
+        UNSAFE.putByte(array, address    , (byte) (c     ));
+        UNSAFE.putByte(array, address + 1, (byte) (c >> 8));
+    }
+}