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ARM: Tweak the integer division operation.

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BUG=none
TEST=test/mjsunit/lithium/DivI.js
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/23536045

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16727 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
rodolph.perfetta@gmail.com 2013-09-16 11:28:18 +00:00
parent 223ac69ff6
commit 39f0ccc2b3
3 changed files with 83 additions and 17 deletions
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5
src/arm/lithium-arm.cc
View File

@ -1373,9 +1373,8 @@ LInstruction* LChunkBuilder::DoDiv(HDiv* instr) {
if (instr->HasPowerOf2Divisor()) {
ASSERT(!instr->CheckFlag(HValue::kCanBeDivByZero));
LOperand* value = UseRegisterAtStart(instr->left());
LDivI* div =
new(zone()) LDivI(value, UseOrConstant(instr->right()), NULL);
return AssignEnvironment(DefineSameAsFirst(div));
LDivI* div = new(zone()) LDivI(value, UseConstant(instr->right()), NULL);
return AssignEnvironment(DefineAsRegister(div));
}
LOperand* dividend = UseRegister(instr->left());
LOperand* divisor = UseRegister(instr->right());

38
src/arm/lithium-codegen-arm.cc
View File

@ -1383,7 +1383,8 @@ void LCodeGen::EmitSignedIntegerDivisionByConstant(
void LCodeGen::DoDivI(LDivI* instr) {
if (instr->hydrogen()->HasPowerOf2Divisor()) {
Register dividend = ToRegister(instr->left());
const Register dividend = ToRegister(instr->left());
const Register result = ToRegister(instr->result());
int32_t divisor = instr->hydrogen()->right()->GetInteger32Constant();
int32_t test_value = 0;
int32_t power = 0;
@ -1394,7 +1395,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
} else {
// Check for (0 / -x) that will produce negative zero.
if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
__ tst(dividend, Operand(dividend));
__ cmp(dividend, Operand::Zero());
DeoptimizeIf(eq, instr->environment());
}
// Check for (kMinInt / -1).
@ -1409,20 +1410,26 @@ void LCodeGen::DoDivI(LDivI* instr) {
if (test_value != 0) {
if (instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
__ cmp(dividend, Operand(0));
__ rsb(dividend, dividend, Operand(0), LeaveCC, lt);
__ mov(dividend, Operand(dividend, ASR, power));
if (divisor > 0) __ rsb(dividend, dividend, Operand(0), LeaveCC, lt);
if (divisor < 0) __ rsb(dividend, dividend, Operand(0), LeaveCC, gt);
__ sub(result, dividend, Operand::Zero(), SetCC);
__ rsb(result, result, Operand::Zero(), LeaveCC, lt);
__ mov(result, Operand(result, ASR, power));
if (divisor > 0) __ rsb(result, result, Operand::Zero(), LeaveCC, lt);
if (divisor < 0) __ rsb(result, result, Operand::Zero(), LeaveCC, gt);
return; // Don't fall through to "__ rsb" below.
} else {
// Deoptimize if remainder is not 0.
__ tst(dividend, Operand(test_value));
DeoptimizeIf(ne, instr->environment());
__ mov(dividend, Operand(dividend, ASR, power));
__ mov(result, Operand(dividend, ASR, power));
if (divisor < 0) __ rsb(result, result, Operand(0));
}
} else {
if (divisor < 0) {
__ rsb(result, dividend, Operand(0));
} else {
__ Move(result, dividend);
}
}
if (divisor < 0) __ rsb(dividend, dividend, Operand(0));
return;
}
@ -1439,12 +1446,15 @@ void LCodeGen::DoDivI(LDivI* instr) {
// Check for (0 / -x) that will produce negative zero.
if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
Label left_not_zero;
Label positive;
if (!instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
// Do the test only if it hadn't be done above.
__ cmp(right, Operand::Zero());
}
__ b(pl, &positive);
__ cmp(left, Operand::Zero());
__ b(ne, &left_not_zero);
__ cmp(right, Operand::Zero());
DeoptimizeIf(mi, instr->environment());
__ bind(&left_not_zero);
DeoptimizeIf(eq, instr->environment());
__ bind(&positive);
}
// Check for (kMinInt / -1).

57
test/mjsunit/lithium/DivI.js Normal file
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@ -0,0 +1,57 @@
// 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 --no-use-osr
function foo(a, b) {
var result = a / 35;
result += 50 / b;
result += a / b;
result += a / -1;
result += a / 1;
result += a / 4;
result += a / -4;
return result / b;
}
foo(700, 5);
var r1 = foo(700, 5);
%OptimizeFunctionOnNextCall(foo);
var r2 = foo(700, 5);
assertEquals(r1, r2);
function boo(value) {
return value / -1;
}
// Test deoptimization of MinInt / -1.
assertEquals(2147483600, boo(-2147483600));
assertEquals(2147483600, boo(-2147483600));
%OptimizeFunctionOnNextCall(boo);
assertEquals(2147483600, boo(-2147483600));
assertEquals(2147483648, boo(-2147483648));