8247408: IdealGraph bit check expression canonicalization

Reviewed-by: aph, kvn, adinn
dragonwell-project · Dec 7, 2020 · 1fcd8f9 · 1fcd8f9
1 parent 9d0ad33
commit 1fcd8f9
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diff --git a/src/hotspot/share/opto/subnode.cpp b/src/hotspot/share/opto/subnode.cpp
@@ -1403,6 +1403,34 @@ Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
     return new BoolNode( cmp, _test.commute() );
   }
 
+  // Change "bool eq/ne (cmp (and X 16) 16)" into "bool ne/eq (cmp (and X 16) 0)".
+  if (cop == Op_CmpI &&
+      (_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
+      cmp1->Opcode() == Op_AndI && cmp2->Opcode() == Op_ConI &&
+      cmp1->in(2)->Opcode() == Op_ConI) {
+    const TypeInt *t12 = phase->type(cmp2)->isa_int();
+    const TypeInt *t112 = phase->type(cmp1->in(2))->isa_int();
+    if (t12 && t12->is_con() && t112 && t112->is_con() &&
+        t12->get_con() == t112->get_con() && is_power_of_2(t12->get_con())) {
+      Node *ncmp = phase->transform(new CmpINode(cmp1, phase->intcon(0)));
+      return new BoolNode(ncmp, _test.negate());
+    }
+  }
+
+  // Same for long type: change "bool eq/ne (cmp (and X 16) 16)" into "bool ne/eq (cmp (and X 16) 0)".
+  if (cop == Op_CmpL &&
+      (_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
+      cmp1->Opcode() == Op_AndL && cmp2->Opcode() == Op_ConL &&
+      cmp1->in(2)->Opcode() == Op_ConL) {
+    const TypeLong *t12 = phase->type(cmp2)->isa_long();
+    const TypeLong *t112 = phase->type(cmp1->in(2))->isa_long();
+    if (t12 && t12->is_con() && t112 && t112->is_con() &&
+        t12->get_con() == t112->get_con() && is_power_of_2(t12->get_con())) {
+      Node *ncmp = phase->transform(new CmpLNode(cmp1, phase->longcon(0)));
+      return new BoolNode(ncmp, _test.negate());
+    }
+  }
+
   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".
   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the
   // test instead.

diff --git a/test/hotspot/jtreg/compiler/c2/TestBit.java b/test/hotspot/jtreg/compiler/c2/TestBit.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2020, 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 compiler.c2;
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.process.ProcessTools;
+
+/*
+ * @test
+ * @bug 8247408
+ * @summary C2 should convert ((var&16) == 16) to ((var&16) != 0) for power-of-two constants
+ * @library /test/lib /
+ *
+ * @run main/othervm compiler.c2.TestBit
+ *
+ * @requires os.arch=="aarch64" | os.arch=="amd64" | os.arch == "ppc64le"
+ * @requires vm.debug == true & vm.flavor == "server" & !vm.graal.enabled
+ */
+public class TestBit {
+
+    static void runTest(String testName) throws Exception {
+        String className = "compiler.c2.TestBit";
+        String[] procArgs = {
+            "-XX:+PrintOptoAssembly",
+            "-XX:CompileCommand=compileonly," + className + "::tst*",
+            className, testName};
+
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(procArgs);
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+        String expectedTestBitInstruction =
+            "ppc64le".equals(System.getProperty("os.arch")) ? "ANDI" :
+            "aarch64".equals(System.getProperty("os.arch")) ? "tb"   :
+            "amd64".equals(System.getProperty("os.arch"))   ? "test" : null;
+
+        if (expectedTestBitInstruction != null) {
+            output.shouldContain(expectedTestBitInstruction);
+        } else {
+            System.err.println("unexpected os.arch");
+        }
+    }
+
+    static final int ITER = 100000; // ~ Tier4CompileThreshold + compilation time
+
+    // dummy volatile variable
+    public static volatile long c = 0;
+
+    // C2 is expected to generate test bit instruction on the test
+    static void tstBitLong(long value) {
+        if (1L == (1L & value)) {
+            c++;
+        } else {
+            c--;
+        }
+    }
+
+    // C2 is expected to generate test bit instruction on the test
+    static void tstBitInt(int value) {
+        if (1 == (1 & value)) {
+            c++;
+        } else {
+            c--;
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (args.length == 0) {
+            // Fork VMs to check their debug compiler output
+            runTest("tstBitLong");
+            runTest("tstBitInt");
+        }
+        if (args.length > 0) {
+            // We are in a forked VM to execute the named test
+            String testName = args[0];
+            switch (testName) {
+            case "tstBitLong":
+                for (int i = 0; i < ITER; i++) {
+                    tstBitLong(i % 2);
+                }
+                break;
+            case "tstBitInt":
+                for (int i = 0; i < ITER; i++) {
+                    tstBitInt(i % 2);
+                }
+                break;
+            default:
+                throw new RuntimeException("unexpected test name " + testName);
+            }
+        }
+    }
+}
diff --git a/test/micro/org/openjdk/bench/vm/compiler/BitTest.java b/test/micro/org/openjdk/bench/vm/compiler/BitTest.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2020, 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 org.openjdk.bench.vm.compiler;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+public class BitTest {
+
+    private static final int COUNT = 1000;
+
+    @Benchmark
+    public int bitTestAndBranch() {
+        int dummy = 0;
+        for (int value = 0; value < COUNT; value++) {
+            dummy++;
+            if ((value & 32) == 32) {
+                dummy = value ^ dummy;
+            } else {
+                dummy = value ^ value;
+            }
+        }
+        return dummy;
+    }
+}