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X64: Port optimization of LMulI to x64.

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Review URL: http://codereview.chromium.org/6701003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7248 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
lrn@chromium.org 2011-03-17 18:14:21 +00:00
parent 6311105e00
commit 94d85de5ba
1 changed files with 42 additions and 2 deletions
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44
src/x64/lithium-codegen-x64.cc
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@ -864,16 +864,56 @@ void LCodeGen::DoMulI(LMulI* instr) {
__ movl(kScratchRegister, left); __ movl(kScratchRegister, left);
} }
bool can_overflow =
instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
if (right->IsConstantOperand()) { if (right->IsConstantOperand()) {
int right_value = ToInteger32(LConstantOperand::cast(right)); int right_value = ToInteger32(LConstantOperand::cast(right));
__ imull(left, left, Immediate(right_value)); if (right_value == -1) {
__ negl(left);
} else if (right_value == 0) {
__ xorl(left, left);
} else if (right_value == 2) {
__ addl(left, left);
} else if (!can_overflow) {
// If the multiplication is known to not overflow, we
// can use operations that don't set the overflow flag
// correctly.
switch (right_value) {
case 1:
// Do nothing.
break;
case 3:
__ leal(left, Operand(left, left, times_2, 0));
break;
case 4:
__ shll(left, Immediate(2));
break;
case 5:
__ leal(left, Operand(left, left, times_4, 0));
break;
case 8:
__ shll(left, Immediate(3));
break;
case 9:
__ leal(left, Operand(left, left, times_8, 0));
break;
case 16:
__ shll(left, Immediate(4));
break;
default:
__ imull(left, left, Immediate(right_value));
break;
}
} else {
__ imull(left, left, Immediate(right_value));
}
} else if (right->IsStackSlot()) { } else if (right->IsStackSlot()) {
__ imull(left, ToOperand(right)); __ imull(left, ToOperand(right));
} else { } else {
__ imull(left, ToRegister(right)); __ imull(left, ToRegister(right));
} }
if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) { if (can_overflow) {
DeoptimizeIf(overflow, instr->environment()); DeoptimizeIf(overflow, instr->environment());
} }