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Fix performace regression due to missed peephole optimization

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opportunity.
Review URL: http://codereview.chromium.org/2002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@286 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
kmillikin@chromium.org 2008-09-11 15:16:08 +00:00
parent 3764f52a4e
commit 4afbecf50e
2 changed files with 10 additions and 2 deletions
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6
src/codegen-arm.cc
View File

@ -948,6 +948,7 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
ASSERT(var()->mode() != Variable::DYNAMIC);
Label exit;
bool may_skip_write = false;
if (init_state == CONST_INIT) {
ASSERT(var()->mode() == Variable::CONST);
// Only the first const initialization must be executed (the slot
@ -957,6 +958,7 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
masm->ldr(r2, ArmCodeGenerator::SlotOperand(masm, scope, this, r2));
masm->cmp(r2, Operand(Factory::the_hole_value()));
masm->b(ne, &exit);
may_skip_write = true;
}
// We must execute the store.
@ -981,7 +983,9 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
masm->mov(r3, Operand(offset));
masm->RecordWrite(r2, r3, r1);
}
masm->bind(&exit);
// If we definitely did not jump over the assignment, we do not need to
// bind the exit label. Doing so can defeat peephole optimization.
if (may_skip_write) masm->bind(&exit);
}
}

6
src/codegen-ia32.cc
View File

@ -975,6 +975,7 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
ASSERT(var()->mode() != Variable::DYNAMIC);
Label exit;
bool may_skip_write = false;
if (init_state == CONST_INIT) {
ASSERT(var()->mode() == Variable::CONST);
// Only the first const initialization must be executed (the slot
@ -984,6 +985,7 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
masm->mov(eax, Ia32CodeGenerator::SlotOperand(masm, scope, this, ecx));
masm->cmp(eax, Factory::the_hole_value());
masm->j(not_equal, &exit);
may_skip_write = true;
}
// We must execute the store.
@ -1003,7 +1005,9 @@ void Slot::GenerateStoreCode(MacroAssembler* masm,
int offset = FixedArray::kHeaderSize + index() * kPointerSize;
masm->RecordWrite(ecx, offset, eax, ebx);
}
masm->bind(&exit);
// If we definitely did not jump over the assignment, we do not need to
// bind the exit label. Doing so can defeat peephole optimization.
if (may_skip_write) masm->bind(&exit);
}
}