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6956668: misbehavior of XOR operator (^) with int

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Optimize cmp_ne(xor(X,1),0) to cmp_eq(X,0) only for boolean values X.

Reviewed-by: never
This commit is contained in:
Vladimir Kozlov 2011-05-31 10:05:36 -07:00
parent c3a7796068
commit a8556d6c01
2 changed files with 70 additions and 0 deletions
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1
hotspot/src/share/vm/opto/subnode.cpp
View File

@ -1101,6 +1101,7 @@ Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
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) ) {

69
hotspot/test/compiler/6956668/Test6956668.java Normal file
View File

@ -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();
}
}
}