Reviewers: ulan,
Description:
NumberUntagD is faster when untagging in a temp register
BUG=
Please review this at https://codereview.chromium.org/23684056/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+14, -13 lines):
M src/ia32/lithium-codegen-ia32.cc
M src/ia32/lithium-ia32.cc
Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc
b/src/ia32/lithium-codegen-ia32.cc
index
860646c2fd60417e2fdfe5640eabe15cb61c0211..b4f3165e5e9e26778c0f12910b6a0f510208b5ea
100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -5285,11 +5285,13 @@ void LCodeGen::EmitNumberUntagDNoSSE2(Register
input_reg,
}
__ bind(&load_smi);
- __ SmiUntag(input_reg); // Untag smi before converting to float.
- __ push(input_reg);
+ // Clobbering a temp is faster than re-tagging the
+ // input register since we avoid dependencies.
+ __ mov(temp_reg, input_reg);
+ __ SmiUntag(temp_reg); // Untag smi before converting to float.
+ __ push(temp_reg);
__ fild_s(Operand(esp, 0));
- __ pop(input_reg);
- __ SmiTag(input_reg); // Retag smi.
+ __ add(esp, Immediate(kPointerSize));
__ bind(&done);
X87CommitWrite(res_reg);
}
@@ -5345,11 +5347,12 @@ void LCodeGen::EmitNumberUntagD(Register input_reg,
ASSERT(mode == NUMBER_CANDIDATE_IS_SMI);
}
- // Smi to XMM conversion
__ bind(&load_smi);
- __ SmiUntag(input_reg); // Untag smi before converting to float.
- __ cvtsi2sd(result_reg, Operand(input_reg));
- __ SmiTag(input_reg); // Retag smi.
+ // Smi to XMM conversion. Clobbering a temp is faster than re-tagging the
+ // input register since we avoid dependencies.
+ __ mov(temp_reg, input_reg);
+ __ SmiUntag(temp_reg); // Untag smi before converting to float.
+ __ cvtsi2sd(result_reg, Operand(temp_reg));
__ bind(&done);
}
@@ -5423,14 +5426,14 @@ void LCodeGen::DoNumberUntagD(LNumberUntagD* instr)
{
LOperand* input = instr->value();
ASSERT(input->IsRegister());
LOperand* temp = instr->temp();
- ASSERT(temp == NULL || temp->IsRegister());
+ ASSERT(temp->IsRegister());
LOperand* result = instr->result();
ASSERT(result->IsDoubleRegister());
Register input_reg = ToRegister(input);
bool deoptimize_on_minus_zero =
instr->hydrogen()->deoptimize_on_minus_zero();
- Register temp_reg = deoptimize_on_minus_zero ? ToRegister(temp) : no_reg;
+ Register temp_reg = ToRegister(temp);
HValue* value = instr->hydrogen()->value();
NumberUntagDMode mode = value->representation().IsSmi()
Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index
07dbf13d19a3d4b20ccfb8d99cdc1ab0ddb1885b..9e315cc2a59cb4ac1a2caf57a13e5623849911ea
100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1933,9 +1933,7 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr)
{
info()->MarkAsDeferredCalling();
LOperand* value = UseRegister(instr->value());
// Temp register only necessary for minus zero check.
- LOperand* temp = instr->deoptimize_on_minus_zero()
- ? TempRegister()
- : NULL;
+ LOperand* temp = TempRegister();
LNumberUntagD* res = new(zone()) LNumberUntagD(value, temp);
return AssignEnvironment(DefineAsRegister(res));
} else if (to.IsSmi()) {
--
--
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