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Deopt on overflow in integer mod.

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R=ulan@chromium.org
BUG=166379

Review URL: https://chromiumcodereview.appspot.com/11618017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13241 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2012-12-19 12:01:22 +00:00
parent b25c040c2c
commit 362218a037
4 changed files with 66 additions and 0 deletions
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5
src/hydrogen-instructions.cc
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@ -1342,6 +1342,11 @@ Range* HMod::InferRange(Zone* zone) {
if (a->CanBeMinusZero() || a->CanBeNegative()) {
result->set_can_be_minus_zero(true);
}
if (right()->range()->Includes(-1) && left()->range()->Includes(kMinInt)) {
SetFlag(HValue::kCanOverflow);
}
if (!right()->range()->CanBeZero()) {
ClearFlag(HValue::kCanBeDivByZero);
}

11
src/ia32/lithium-codegen-ia32.cc
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@ -1168,6 +1168,17 @@ void LCodeGen::DoModI(LModI* instr) {
// Slow case, using idiv instruction.
__ bind(&slow);
// Check for (kMinInt % -1).
if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
Label left_not_min_int;
__ cmp(left_reg, kMinInt);
__ j(not_zero, &left_not_min_int, Label::kNear);
__ cmp(right_reg, -1);
DeoptimizeIf(zero, instr->environment());
__ bind(&left_not_min_int);
}
// Sign extend to edx.
__ cdq();

11
src/x64/lithium-codegen-x64.cc
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@ -1016,6 +1016,17 @@ void LCodeGen::DoModI(LModI* instr) {
// Slow case, using idiv instruction.
__ bind(&slow);
// Check for (kMinInt % -1).
if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
Label left_not_min_int;
__ cmpl(left_reg, Immediate(kMinInt));
__ j(not_zero, &left_not_min_int, Label::kNear);
__ cmpl(right_reg, Immediate(-1));
DeoptimizeIf(zero, instr->environment());
__ bind(&left_not_min_int);
}
// Sign extend eax to edx.
// (We are using only the low 32 bits of the values.)
__ cdq();

39
test/mjsunit/regress/regress-166379.js Normal file
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@ -0,0 +1,39 @@
// Copyright 2012 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
function mod(a, b) { return a % b; }
// Feed integer type info and optimize.
assertEquals(0, mod(4, 2));
assertEquals(1, mod(3, 2));
%OptimizeFunctionOnNextCall(mod);
// Surprise mod with overflow.
assertEquals(-Infinity, 1/mod(-2147483648, -1));