From 3f1a833524328095473743d5d8bad019143f7a51 Mon Sep 17 00:00:00 2001 From: "yangguo@chromium.org" Date: Wed, 30 Oct 2013 10:22:52 +0000 Subject: [PATCH] Do not remove HAdd with zero if the other operand is a double. 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 --- src/hydrogen-instructions.cc | 11 ++++++-- test/mjsunit/regress/regress-add-minus-zero.js | 38 ++++++++++++++++++++++++++ 2 files changed, 47 insertions(+), 2 deletions(-) create mode 100644 test/mjsunit/regress/regress-add-minus-zero.js diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc index 6da6774..206ab7e 100644 --- a/src/hydrogen-instructions.cc +++ b/src/hydrogen-instructions.cc @@ -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; } diff --git a/test/mjsunit/regress/regress-add-minus-zero.js b/test/mjsunit/regress/regress-add-minus-zero.js new file mode 100644 index 0000000..0b4af75 --- /dev/null +++ b/test/mjsunit/regress/regress-add-minus-zero.js @@ -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())); + -- 2.7.4