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Do not remove HAdd with zero if the other operand is a double.

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The other operand might be minus zero, and -0 + 0 = +0

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/52173003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17432 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2013-10-30 10:22:52 +00:00
parent 9e88c23cbf
commit 3f1a833524
2 changed files with 47 additions and 2 deletions
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11
src/hydrogen-instructions.cc
View File

@ -1255,8 +1255,15 @@ static bool IsIdentityOperation(HValue* arg1, HValue* arg2, int32_t identity) {
HValue* HAdd::Canonicalize() {
if (IsIdentityOperation(left(), right(), 0)) return left();
if (IsIdentityOperation(right(), left(), 0)) return right();
// Adding 0 is an identity operation except in case of -0: -0 + 0 = +0
if (IsIdentityOperation(left(), right(), 0) &&
!left()->representation().IsDouble()) { // Left could be -0.
return left();
}
if (IsIdentityOperation(right(), left(), 0) &&
!left()->representation().IsDouble()) { // Right could be -0.
return right();
}
return this;
}

38
test/mjsunit/regress/regress-add-minus-zero.js Normal file
View File

@ -0,0 +1,38 @@
// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Flags: --allow-natives-syntax
var o = { a: 0 };
function f(x) { return -o.a + 0; };
assertEquals("Infinity", String(1/f()));
assertEquals("Infinity", String(1/f()));
%OptimizeFunctionOnNextCall(f);
assertEquals("Infinity", String(1/f()));