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Fix a bug that Math.round() returns incorrect results for huge integers.

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Review URL: http://codereview.chromium.org/567011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3764 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
lrn@chromium.org 2010-02-02 09:14:22 +00:00
parent 325d3ef224
commit 29229e9b8c
2 changed files with 55 additions and 1 deletions
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4
src/runtime.cc
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@ -4662,7 +4662,9 @@ static Object* Runtime_Math_round(Arguments args) {
CONVERT_DOUBLE_CHECKED(x, args[0]);
if (signbit(x) && x >= -0.5) return Heap::minus_zero_value();
return Heap::NumberFromDouble(floor(x + 0.5));
double integer = ceil(x);
if (integer - x > 0.5) { integer -= 1.0; }
return Heap::NumberFromDouble(integer);
}

52
test/mjsunit/math-round.js Normal file
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@ -0,0 +1,52 @@
// Copyright 2010 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.
assertEquals(0, Math.round(0));
assertEquals(-0, Math.round(-0));
assertEquals(Infinity, Math.round(Infinity));
assertEquals(-Infinity, Math.round(-Infinity));
assertNaN(Math.round(NaN));
assertEquals(1, Math.round(0.5));
assertEquals(1, Math.round(0.7));
assertEquals(1, Math.round(1));
assertEquals(1, Math.round(1.1));
assertEquals(1, Math.round(1.49999));
assertEquals(1/-0, 1/Math.round(-0.5)); // Test for -0 result.
assertEquals(-1, Math.round(-0.5000000000000001));
assertEquals(-1, Math.round(-0.7));
assertEquals(-1, Math.round(-1));
assertEquals(-1, Math.round(-1.1));
assertEquals(-1, Math.round(-1.49999));
assertEquals(-1, Math.round(-1.5));
assertEquals(9007199254740990, Math.round(9007199254740990));
assertEquals(9007199254740991, Math.round(9007199254740991));
assertEquals(-9007199254740990, Math.round(-9007199254740990));
assertEquals(-9007199254740991, Math.round(-9007199254740991));
assertEquals(Number.MAX_VALUE, Math.round(Number.MAX_VALUE));
assertEquals(-Number.MAX_VALUE, Math.round(-Number.MAX_VALUE));