Reviewers: danno, Benedikt Meurer, Paul Lind, kisg, palfia, dusmil,
Description:
MIPS: Remove uses of RangeCanInclude() in flooring division by power of 2.
Port r19877 (17029d3)
Original commit message:
Drive-By-Fix: Improve ARM code generation for flooring division by
power of 2.
BUG=v8:3204
LOG=y
Please review this at https://codereview.chromium.org/195893013/
SVN Base: https://github.com/v8/v8.git@gbl
Affected files (+28, -19 lines):
M src/mips/lithium-codegen-mips.cc
M src/mips/lithium-mips.cc
Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc
b/src/mips/lithium-codegen-mips.cc
index
292ce13f24cc9d4b39de3bbbac953f91cef33032..0f562fb899eeb4b2e68b37a2e79afe6b97bc56fc
100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1195,39 +1195,48 @@ void LCodeGen::DoMultiplyAddD(LMultiplyAddD* instr)
{
void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
Register dividend = ToRegister(instr->dividend());
+ Register result = ToRegister(instr->result());
int32_t divisor = instr->divisor();
- ASSERT(dividend.is(ToRegister(instr->result())));
Register scratch = scratch0();
+ ASSERT(!scratch.is(dividend));
// If the divisor is positive, things are easy: There can be no deopts
and we
// can simply do an arithmetic right shift.
if (divisor == 1) return;
uint16_t shift = WhichPowerOf2Abs(divisor);
if (divisor > 1) {
- __ sra(dividend, dividend, shift);
+ __ sra(result, dividend, shift);
return;
}
// If the divisor is negative, we have to negate and handle edge cases.
- Label not_kmin_int, done;
- __ Subu(scratch, zero_reg, dividend);
+ if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+ __ Move(scratch, dividend);
+ }
+ __ Subu(result, zero_reg, dividend);
if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
- DeoptimizeIf(eq, instr->environment(), scratch, Operand(zero_reg));
+ DeoptimizeIf(eq, instr->environment(), result, Operand(zero_reg));
}
- if (instr->hydrogen()->left()->RangeCanInclude(kMinInt)) {
+ if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
// Note that we could emit branch-free code, but that would need one
more
// register.
- __ Branch(¬_kmin_int, ne, dividend, Operand(kMinInt));
+
+ __ Xor(at, scratch, result);
if (divisor == -1) {
- DeoptimizeIf(al, instr->environment());
+ DeoptimizeIf(ge, instr->environment(), at, Operand(zero_reg));
+ __ sra(result, dividend, shift);
} else {
- __ li(dividend, Operand(kMinInt / divisor));
+ Label no_overflow, done;
+ __ Branch(&no_overflow, lt, at, Operand(zero_reg));
+ __ li(result, Operand(kMinInt / divisor));
__ Branch(&done);
+ __ bind(&no_overflow);
+ __ sra(result, dividend, shift);
+ __ bind(&done);
}
+ } else {
+ __ sra(result, dividend, shift);
}
- __ bind(¬_kmin_int);
- __ sra(dividend, scratch, shift);
- __ bind(&done);
}
Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index
93acbab5f31f98246db6aade73c3e5cdfd12c3d5..68392a33e1d1d41c43adbd5aa09766e931afe1cc
100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1280,13 +1280,13 @@ LInstruction* LChunkBuilder::DoDiv(HDiv* instr) {
LInstruction* LChunkBuilder::DoFlooringDivByPowerOf2I(HMathFloorOfDiv*
instr) {
LOperand* dividend = UseRegisterAtStart(instr->left());
int32_t divisor = instr->right()->GetInteger32Constant();
- LInstruction* result =
- DefineSameAsFirst(
- new(zone()) LFlooringDivByPowerOf2I(dividend, divisor));
- bool can_deopt =
- (instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) ||
- (instr->left()->RangeCanInclude(kMinInt) && divisor == -1);
- return can_deopt ? AssignEnvironment(result) : result;
+ LInstruction* result = DefineAsRegister(new(zone())
LFlooringDivByPowerOf2I(
+ dividend, divisor));
+ if ((instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) ||
+ (instr->CheckFlag(HValue::kLeftCanBeMinInt) && divisor == -1)) {
+ result = AssignEnvironment(result);
+ }
+ return result;
}
--
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