changeset 2505:33e2b8f1d466

6956668: misbehavior of XOR operator (^) with int Summary: optimize cmp_ne(xor(X,1),0) to cmp_eq(X,0) only for boolean values X. Reviewed-by: never
author kvn
date Tue, 31 May 2011 10:05:36 -0700
parents b2cb497dec28
children 60b8287df30e
files src/share/vm/opto/subnode.cpp test/compiler/6956668/Test6956668.java
diffstat 2 files changed, 70 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/opto/subnode.cpp	Fri May 27 12:47:48 2011 -0700
+++ b/src/share/vm/opto/subnode.cpp	Tue May 31 10:05:36 2011 -0700
@@ -1101,6 +1101,7 @@
   if( cmp2_type == TypeInt::ZERO &&
       cmp1_op == Op_XorI &&
       j_xor->in(1) != j_xor &&          // An xor of itself is dead
+      phase->type( j_xor->in(1) ) == TypeInt::BOOL &&
       phase->type( j_xor->in(2) ) == TypeInt::ONE &&
       (_test._test == BoolTest::eq ||
        _test._test == BoolTest::ne) ) {
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/6956668/Test6956668.java	Tue May 31 10:05:36 2011 -0700
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2011, 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 6956668
+ * @summary misbehavior of XOR operator (^) with int
+ *
+ * @run main/othervm -Xbatch Test6956668
+ */
+
+
+public class Test6956668 {
+
+   public static int bitTest() {
+      int result = 0;
+
+      int testValue = 73;
+      int bitCount = Integer.bitCount(testValue);
+
+      if (testValue != 0) {
+         int gap = Long.numberOfTrailingZeros(testValue);
+         testValue >>>= gap;
+
+         while (testValue != 0) {
+            result++;
+
+            if ((testValue ^= 0x1) != 0) {
+               gap = Long.numberOfTrailingZeros(testValue);
+               testValue >>>= gap;
+            }
+         }
+      }
+
+      if (bitCount != result) {
+         System.out.println("ERROR: " + bitCount + " != " + result);
+         System.exit(97);
+      }
+
+      return (result);
+   }
+
+   public static void main(String[] args) {
+      for (int i = 0; i < 100000; i++) {
+         int ct = bitTest();
+      }
+   }
+}