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Add fast negative checks for symbol equality: If we're comparing

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two symbols, they're only equal if the objects are identical.
Review URL: http://codereview.chromium.org/125184

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2188 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
kasperl@chromium.org 2009-06-16 12:54:07 +00:00
parent 52dfeca5f2
commit 01216a069b
2 changed files with 39 additions and 5 deletions
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5
src/date-delay.js
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@ -150,6 +150,8 @@ var DST_offset_cache = {
};
// NOTE: The implementation relies on the fact that no time zones have
// more than one daylight savings offset change per month.
function DaylightSavingsOffset(t) {
// Load the cache object from the builtins object.
var cache = DST_offset_cache;
@ -530,7 +532,8 @@ function GetUTCHoursFrom(aDate) {
function GetFullYearFrom(aDate) {
var t = GetTimeFrom(aDate);
if ($isNaN(t)) return t;
return YearFromTime(LocalTimeNoCheck(t));
// Ignore the DST offset for year computations.
return YearFromTime(t + local_time_offset);
}

39
src/ia32/codegen-ia32.cc
View File

@ -1806,6 +1806,12 @@ class CompareStub: public CodeStub {
return (static_cast<int>(cc_) << 1) | (strict_ ? 1 : 0);
}
// Branch to the label if the given object isn't a symbol.
void BranchIfNonSymbol(MacroAssembler* masm,
Label* label,
Register object,
Register scratch);
#ifdef DEBUG
void Print() {
PrintF("CompareStub (cc %d), (strict %s)\n",
@ -6992,17 +6998,16 @@ void CompareStub::Generate(MacroAssembler* masm) {
__ bind(&slow);
}
// Save the return address (and get it off the stack).
// Push arguments below the return address.
__ pop(ecx);
// Push arguments.
__ push(eax);
__ push(edx);
__ push(ecx);
// Inlined floating point compare.
// Call builtin if operands are not floating point or smi.
FloatingPointHelper::CheckFloatOperands(masm, &call_builtin, ebx);
Label check_for_symbols;
FloatingPointHelper::CheckFloatOperands(masm, &check_for_symbols, ebx);
FloatingPointHelper::LoadFloatOperands(masm, ecx);
__ FCmp();
@ -7026,6 +7031,18 @@ void CompareStub::Generate(MacroAssembler* masm) {
__ mov(eax, 1);
__ ret(2 * kPointerSize); // eax, edx were pushed
// Fast negative check for symbol-to-symbol equality.
__ bind(&check_for_symbols);
if (cc_ == equal) {
BranchIfNonSymbol(masm, &call_builtin, eax, ecx);
BranchIfNonSymbol(masm, &call_builtin, edx, ecx);
// We've already checked for object identity, so if both operands
// are symbols they aren't equal. Register eax already holds a
// non-zero value, which indicates not equal, so just return.
__ ret(2 * kPointerSize);
}
__ bind(&call_builtin);
// must swap argument order
__ pop(ecx);
@ -7059,6 +7076,20 @@ void CompareStub::Generate(MacroAssembler* masm) {
}
void CompareStub::BranchIfNonSymbol(MacroAssembler* masm,
Label* label,
Register object,
Register scratch) {
__ test(object, Immediate(kSmiTagMask));
__ j(zero, label);
__ mov(scratch, FieldOperand(object, HeapObject::kMapOffset));
__ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
__ and_(scratch, kIsSymbolMask | kIsNotStringMask);
__ cmp(scratch, kSymbolTag | kStringTag);
__ j(not_equal, label);
}
void StackCheckStub::Generate(MacroAssembler* masm) {
// Because builtins always remove the receiver from the stack, we
// have to fake one to avoid underflowing the stack. The receiver