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Skip some conditional deopts for Div/Mul when all uses are truncating.

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- set "can be minus zero" flag properly so minus-zero checks are skipped
- skip "integer result?" check in division code when uses are truncating
- drive-by cleanup: consolidated computation of kCanOverflow flag for Add/Sub into range inference phase

BUG=v8:2132
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/16741002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15060 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
jkummerow@chromium.org 2013-06-11 11:43:57 +00:00
parent f68d6a10f8
commit 9447014780
7 changed files with 195 additions and 69 deletions
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48
src/arm/lithium-codegen-arm.cc
View File

@ -1419,8 +1419,7 @@ void LCodeGen::EmitSignedIntegerDivisionByConstant(
void LCodeGen::DoDivI(LDivI* instr) {
if (instr->hydrogen()->HasPowerOf2Divisor()) {
Register dividend = ToRegister(instr->left());
int32_t divisor =
HConstant::cast(instr->hydrogen()->right())->Integer32Value();
int32_t divisor = instr->hydrogen()->right()->GetInteger32Constant();
int32_t test_value = 0;
int32_t power = 0;
@ -1443,10 +1442,19 @@ void LCodeGen::DoDivI(LDivI* instr) {
}
if (test_value != 0) {
// Deoptimize if remainder is not 0.
__ tst(dividend, Operand(test_value));
DeoptimizeIf(ne, instr->environment());
__ mov(dividend, Operand(dividend, ASR, power));
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);
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));
}
}
if (divisor < 0) __ rsb(dividend, dividend, Operand(0));
@ -1487,11 +1495,14 @@ void LCodeGen::DoDivI(LDivI* instr) {
CpuFeatureScope scope(masm(), SUDIV);
__ sdiv(result, left, right);
// Compute remainder and deopt if it's not zero.
const Register remainder = scratch0();
__ mls(remainder, result, right, left);
__ cmp(remainder, Operand::Zero());
DeoptimizeIf(ne, instr->environment());
if (!instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
// Compute remainder and deopt if it's not zero.
const Register remainder = scratch0();
__ mls(remainder, result, right, left);
__ cmp(remainder, Operand::Zero());
DeoptimizeIf(ne, instr->environment());
}
} else {
const DoubleRegister vleft = ToDoubleRegister(instr->temp());
const DoubleRegister vright = double_scratch0();
@ -1500,14 +1511,17 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ vcvt_f64_s32(vleft, vleft.low());
__ vcvt_f64_s32(vright, vright.low());
__ vdiv(vleft, vleft, vright); // vleft now contains the result.
// Convert back to integer32; deopt if exact conversion is not possible.
// Use vright as scratch register.
__ vcvt_s32_f64(vright.low(), vleft);
__ vmov(result, vright.low());
__ vcvt_f64_s32(vright, vright.low());
__ VFPCompareAndSetFlags(vleft, vright);
DeoptimizeIf(ne, instr->environment());
if (!instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
// Deopt if exact conversion to integer was not possible.
// Use vright as scratch register.
__ vcvt_f64_s32(vright, vright.low());
__ VFPCompareAndSetFlags(vleft, vright);
DeoptimizeIf(ne, instr->environment());
}
}
}

67
src/hydrogen-instructions.cc
View File

@ -528,6 +528,17 @@ bool HValue::CheckUsesForFlag(Flag f) {
}
bool HValue::HasAtLeastOneUseWithFlagAndNoneWithout(Flag f) {
bool return_value = false;
for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
if (it.value()->IsSimulate()) continue;
if (!it.value()->CheckFlag(f)) return false;
return_value = true;
}
return return_value;
}
HUseIterator::HUseIterator(HUseListNode* head) : next_(head) {
Advance();
}
@ -1429,14 +1440,6 @@ HValue* HBitNot::Canonicalize() {
}
HValue* HArithmeticBinaryOperation::Canonicalize() {
if (representation().IsInteger32() && CheckUsesForFlag(kTruncatingToInt32)) {
ClearFlag(kCanOverflow);
}
return this;
}
static bool IsIdentityOperation(HValue* arg1, HValue* arg2, int32_t identity) {
return arg1->representation().IsSpecialization() &&
arg2->EqualsInteger32Constant(identity);
@ -1446,13 +1449,13 @@ 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();
return HArithmeticBinaryOperation::Canonicalize();
return this;
}
HValue* HSub::Canonicalize() {
if (IsIdentityOperation(left(), right(), 0)) return left();
return HArithmeticBinaryOperation::Canonicalize();
return this;
}
@ -1758,11 +1761,13 @@ Range* HAdd::InferRange(Zone* zone) {
Range* a = left()->range();
Range* b = right()->range();
Range* res = a->Copy(zone);
if (!res->AddAndCheckOverflow(b)) {
if (!res->AddAndCheckOverflow(b) ||
CheckFlag(kAllUsesTruncatingToInt32)) {
ClearFlag(kCanOverflow);
}
bool m0 = a->CanBeMinusZero() && b->CanBeMinusZero();
res->set_can_be_minus_zero(m0);
if (!CheckFlag(kAllUsesTruncatingToInt32)) {
res->set_can_be_minus_zero(a->CanBeMinusZero() && b->CanBeMinusZero());
}
return res;
} else {
return HValue::InferRange(zone);
@ -1775,10 +1780,13 @@ Range* HSub::InferRange(Zone* zone) {
Range* a = left()->range();
Range* b = right()->range();
Range* res = a->Copy(zone);
if (!res->SubAndCheckOverflow(b)) {
if (!res->SubAndCheckOverflow(b) ||
CheckFlag(kAllUsesTruncatingToInt32)) {
ClearFlag(kCanOverflow);
}
res->set_can_be_minus_zero(a->CanBeMinusZero() && b->CanBeZero());
if (!CheckFlag(kAllUsesTruncatingToInt32)) {
res->set_can_be_minus_zero(a->CanBeMinusZero() && b->CanBeZero());
}
return res;
} else {
return HValue::InferRange(zone);
@ -1792,11 +1800,16 @@ Range* HMul::InferRange(Zone* zone) {
Range* b = right()->range();
Range* res = a->Copy(zone);
if (!res->MulAndCheckOverflow(b)) {
// Clearing the kCanOverflow flag when kAllUsesAreTruncatingToInt32
// would be wrong, because truncated integer multiplication is too
// precise and therefore not the same as converting to Double and back.
ClearFlag(kCanOverflow);
}
bool m0 = (a->CanBeZero() && b->CanBeNegative()) ||
(a->CanBeNegative() && b->CanBeZero());
res->set_can_be_minus_zero(m0);
if (!CheckFlag(kAllUsesTruncatingToInt32)) {
bool m0 = (a->CanBeZero() && b->CanBeNegative()) ||
(a->CanBeNegative() && b->CanBeZero());
res->set_can_be_minus_zero(m0);
}
return res;
} else {
return HValue::InferRange(zone);
@ -1809,12 +1822,14 @@ Range* HDiv::InferRange(Zone* zone) {
Range* a = left()->range();
Range* b = right()->range();
Range* result = new(zone) Range();
if (a->CanBeMinusZero()) {
result->set_can_be_minus_zero(true);
}
if (!CheckFlag(kAllUsesTruncatingToInt32)) {
if (a->CanBeMinusZero()) {
result->set_can_be_minus_zero(true);
}
if (a->CanBeZero() && b->CanBeNegative()) {
result->set_can_be_minus_zero(true);
if (a->CanBeZero() && b->CanBeNegative()) {
result->set_can_be_minus_zero(true);
}
}
if (!a->Includes(kMinInt) || !b->Includes(-1)) {
@ -1846,7 +1861,7 @@ Range* HMod::InferRange(Zone* zone) {
Range* result = new(zone) Range(left_can_be_negative ? -positive_bound : 0,
a->CanBePositive() ? positive_bound : 0);
if (left_can_be_negative) {
if (left_can_be_negative && !CheckFlag(kAllUsesTruncatingToInt32)) {
result->set_can_be_minus_zero(true);
}
@ -2298,10 +2313,6 @@ bool HBinaryOperation::IgnoreObservedOutputRepresentation(
current_rep.IsInteger32() &&
// Mul in Integer32 mode would be too precise.
!this->IsMul() &&
// TODO(jkummerow): Remove blacklisting of Div when the Div
// instruction has learned not to deopt when the remainder is
// non-zero but all uses are truncating.
!this->IsDiv() &&
CheckUsesForFlag(kTruncatingToInt32);
}

12
src/hydrogen-instructions.h
View File

@ -54,6 +54,7 @@ class LChunkBuilder;
#define HYDROGEN_ABSTRACT_INSTRUCTION_LIST(V) \
V(ArithmeticBinaryOperation) \
V(BinaryOperation) \
V(BitwiseBinaryOperation) \
V(ControlInstruction) \
@ -797,6 +798,7 @@ class HValue: public ZoneObject {
kAllowUndefinedAsNaN,
kIsArguments,
kTruncatingToInt32,
kAllUsesTruncatingToInt32,
// Set after an instruction is killed.
kIsDead,
// Instructions that are allowed to produce full range unsigned integer
@ -996,6 +998,9 @@ class HValue: public ZoneObject {
// Returns true if the flag specified is set for all uses, false otherwise.
bool CheckUsesForFlag(Flag f);
// Returns true if the flag specified is set for all uses, and this set
// of uses is non-empty.
bool HasAtLeastOneUseWithFlagAndNoneWithout(Flag f);
GVNFlagSet gvn_flags() const { return gvn_flags_; }
void SetGVNFlag(GVNFlag f) { gvn_flags_.Add(f); }
@ -3856,7 +3861,7 @@ class HArithmeticBinaryOperation: public HBinaryOperation {
: representation();
}
virtual HValue* Canonicalize();
DECLARE_ABSTRACT_INSTRUCTION(ArithmeticBinaryOperation)
private:
virtual bool IsDeletable() const { return true; }
@ -4488,9 +4493,8 @@ class HDiv: public HArithmeticBinaryOperation {
HValue* right);
bool HasPowerOf2Divisor() {
if (right()->IsConstant() &&
HConstant::cast(right())->HasInteger32Value()) {
int32_t value = HConstant::cast(right())->Integer32Value();
if (right()->IsInteger32Constant()) {
int32_t value = right()->GetInteger32Constant();
return value != 0 && (IsPowerOf2(value) || IsPowerOf2(-value));
}

16
src/hydrogen.cc
View File

@ -2091,6 +2091,22 @@ void HGraph::FinalizeUniqueValueIds() {
void HGraph::Canonicalize() {
HPhase phase("H_Canonicalize", this);
// Before removing no-op instructions, save their semantic value.
// We must be careful not to set the flag unnecessarily, because GVN
// cannot identify two instructions when their flag value differs.
for (int i = 0; i < blocks()->length(); ++i) {
HInstruction* instr = blocks()->at(i)->first();
while (instr != NULL) {
if (instr->IsArithmeticBinaryOperation() &&
instr->representation().IsInteger32() &&
instr->HasAtLeastOneUseWithFlagAndNoneWithout(
HInstruction::kTruncatingToInt32)) {
instr->SetFlag(HInstruction::kAllUsesTruncatingToInt32);
}
instr = instr->next();
}
}
// Perform actual Canonicalization pass.
for (int i = 0; i < blocks()->length(); ++i) {
HInstruction* instr = blocks()->at(i)->first();
while (instr != NULL) {

38
src/ia32/lithium-codegen-ia32.cc
View File

@ -1338,8 +1338,7 @@ void LCodeGen::DoModI(LModI* instr) {
void LCodeGen::DoDivI(LDivI* instr) {
if (!instr->is_flooring() && instr->hydrogen()->HasPowerOf2Divisor()) {
Register dividend = ToRegister(instr->left());
int32_t divisor =
HConstant::cast(instr->hydrogen()->right())->Integer32Value();
int32_t divisor = instr->hydrogen()->right()->GetInteger32Constant();
int32_t test_value = 0;
int32_t power = 0;
@ -1362,10 +1361,26 @@ void LCodeGen::DoDivI(LDivI* instr) {
}
if (test_value != 0) {
// Deoptimize if remainder is not 0.
__ test(dividend, Immediate(test_value));
DeoptimizeIf(not_zero, instr->environment());
__ sar(dividend, power);
if (instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
Label done, negative;
__ cmp(dividend, 0);
__ j(less, &negative, Label::kNear);
__ sar(dividend, power);
__ jmp(&done, Label::kNear);
__ bind(&negative);
__ neg(dividend);
__ sar(dividend, power);
if (divisor > 0) __ neg(dividend);
__ bind(&done);
return; // Don't fall through to "__ neg" below.
} else {
// Deoptimize if remainder is not 0.
__ test(dividend, Immediate(test_value));
DeoptimizeIf(not_zero, instr->environment());
__ sar(dividend, power);
}
}
if (divisor < 0) __ neg(dividend);
@ -1412,11 +1427,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ cdq();
__ idiv(right_reg);
if (!instr->is_flooring()) {
// Deoptimize if remainder is not 0.
__ test(edx, Operand(edx));
DeoptimizeIf(not_zero, instr->environment());
} else {
if (instr->is_flooring()) {
Label done;
__ test(edx, edx);
__ j(zero, &done, Label::kNear);
@ -1424,6 +1435,11 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ sar(edx, 31);
__ add(eax, edx);
__ bind(&done);
} else if (!instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
// Deoptimize if remainder is not 0.
__ test(edx, Operand(edx));
DeoptimizeIf(not_zero, instr->environment());
}
}

35
src/x64/lithium-codegen-x64.cc
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@ -1257,10 +1257,26 @@ void LCodeGen::DoDivI(LDivI* instr) {
}
if (test_value != 0) {
// Deoptimize if remainder is not 0.
__ testl(dividend, Immediate(test_value));
DeoptimizeIf(not_zero, instr->environment());
__ sarl(dividend, Immediate(power));
if (instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
Label done, negative;
__ cmpl(dividend, Immediate(0));
__ j(less, &negative, Label::kNear);
__ sarl(dividend, Immediate(power));
__ jmp(&done, Label::kNear);
__ bind(&negative);
__ negl(dividend);
__ sarl(dividend, Immediate(power));
if (divisor > 0) __ negl(dividend);
__ bind(&done);
return; // Don't fall through to "__ neg" below.
} else {
// Deoptimize if remainder is not 0.
__ testl(dividend, Immediate(test_value));
DeoptimizeIf(not_zero, instr->environment());
__ sarl(dividend, Immediate(power));
}
}
if (divisor < 0) __ negl(dividend);
@ -1307,11 +1323,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ cdq();
__ idivl(right_reg);
if (!instr->is_flooring()) {
// Deoptimize if remainder is not 0.
__ testl(rdx, rdx);
DeoptimizeIf(not_zero, instr->environment());
} else {
if (instr->is_flooring()) {
Label done;
__ testl(rdx, rdx);
__ j(zero, &done, Label::kNear);
@ -1319,6 +1331,11 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ sarl(rdx, Immediate(31));
__ addl(rax, rdx);
__ bind(&done);
} else if (!instr->hydrogen()->CheckFlag(
HInstruction::kAllUsesTruncatingToInt32)) {
// Deoptimize if remainder is not 0.
__ testl(rdx, rdx);
DeoptimizeIf(not_zero, instr->environment());
}
}

48
test/mjsunit/regress/regress-2132.js Normal file
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@ -0,0 +1,48 @@
// 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
function mul(x, y) {
return (x * y) | 0;
}
mul(0, 0);
mul(0, 0);
%OptimizeFunctionOnNextCall(mul);
assertEquals(0, mul(0, -1));
assertTrue(%GetOptimizationStatus(mul) != 2);
function div(x, y) {
return (x / y) | 0;
}
div(4, 2);
div(4, 2);
%OptimizeFunctionOnNextCall(div);
assertEquals(1, div(5, 3));
assertTrue(%GetOptimizationStatus(div) != 2);