Author: [email protected]
Date: Tue Jun 16 05:54:07 2009
New Revision: 2188
Modified:
branches/bleeding_edge/src/date-delay.js
branches/bleeding_edge/src/ia32/codegen-ia32.cc
Log:
Add fast negative checks for symbol equality: If we're comparing
two symbols, they're only equal if the objects are identical.
Review URL: http://codereview.chromium.org/125184
Modified: branches/bleeding_edge/src/date-delay.js
==============================================================================
--- branches/bleeding_edge/src/date-delay.js (original)
+++ branches/bleeding_edge/src/date-delay.js Tue Jun 16 05:54:07 2009
@@ -150,6 +150,8 @@
};
+// 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 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);
}
Modified: branches/bleeding_edge/src/ia32/codegen-ia32.cc
==============================================================================
--- branches/bleeding_edge/src/ia32/codegen-ia32.cc (original)
+++ branches/bleeding_edge/src/ia32/codegen-ia32.cc Tue Jun 16 05:54:07 2009
@@ -1806,6 +1806,12 @@
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 @@
__ 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 @@
__ 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);
@@ -7056,6 +7073,20 @@
// Call the native; it returns -1 (less), 0 (equal), or 1 (greater)
// tagged as a small integer.
__ InvokeBuiltin(builtin, JUMP_FUNCTION);
+}
+
+
+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);
}
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