8260709: C2: assert(false) failed: unscheduable graph

Reviewed-by: thartmann, chagedorn

Author: rwestrel

src/hotspot/share/opto/loopnode.hpp

@@ -1607,6 +1607,8 @@ class PhaseIdealLoop : public PhaseTransform {
   void check_long_counted_loop(IdealLoopTree* loop, Node* x) NOT_DEBUG_RETURN;
 
   LoopNode* create_inner_head(IdealLoopTree* loop, LongCountedLoopNode* head, LongCountedLoopEndNode* exit_test);
+
+  bool is_safe_load_ctrl(Node* ctrl);
 };
 
 

src/hotspot/share/opto/loopopts.cpp

@@ -1429,7 +1429,7 @@ void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
         // If n is a load, and the late control is the same as the current
         // control, then the cloning of n is a pointless exercise, because
         // GVN will ensure that we end up where we started.
-        if (!n->is_Load() || late_load_ctrl != n_ctrl) {
+        if (!n->is_Load() || (late_load_ctrl != n_ctrl && is_safe_load_ctrl(late_load_ctrl))) {
           for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
             Node *u = n->last_out(j); // Clone private computation per use
             _igvn.rehash_node_delayed(u);
@@ -1525,6 +1525,13 @@ void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
   }
 }
 
+bool PhaseIdealLoop::is_safe_load_ctrl(Node* ctrl) {
+  if (ctrl->is_Proj() && ctrl->in(0)->is_Call() && ctrl->has_out_with(Op_Catch)) {
+    return false;
+  }
+  return true;
+}
+
 //------------------------------split_if_with_blocks---------------------------
 // Check for aggressive application of 'split-if' optimization,
 // using basic block level info.

test/hotspot/jtreg/compiler/loopopts/TestLoadPinnedAfterAllocate.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2021, 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 8260709
+ * @summary C2: assert(false) failed: unscheduable graph
+ *
+ * @run main/othervm -XX:-BackgroundCompilation TestLoadPinnedAfterAllocate
+ *
+ */
+
+public class TestLoadPinnedAfterAllocate {
+    private int field;
+    private static volatile int barrier;
+    private static Object field2;
+
+    public static void main(String[] args) {
+        final TestLoadPinnedAfterAllocate test = new TestLoadPinnedAfterAllocate();
+        for (int i = 0; i < 20_000; i++) {
+            test.test(1, 10);
+        }
+    }
+
+    private int test(int start, int stop) {
+        int[] array = new int[10];
+        for (int j = 0; j < 10; j++) {
+            barrier = 1;
+            // early control for field load below
+            for (int i = 1; i < 10; i *= 2) {
+                field2 = array;
+                array = new int[10];
+                // late control for field load below
+            }
+        }
+        int v = field;
+        array[0] = v;
+        return v+v;
+    }
+}