Optimize the equality check case of ICCompare stubs.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
===================================================================
--- src/ia32/code-stubs-ia32.cc	(revision 9957)
+++ src/ia32/code-stubs-ia32.cc	(working copy)
@@ -6502,6 +6502,28 @@
 }
 
 
+void ICCompareStub::GenerateKnownObjects(MacroAssembler* masm,
+                                         Handle<Map> map) {

[Kevin Millikin (Chromium), 2011/11/11 10:12:34]

No need for the extra argument.

[Rico, 2011/11/15 10:12:26]

Done.

+  Label miss;
+  __ mov(ecx, edx);
+  __ and_(ecx, eax);
+  __ JumpIfSmi(ecx, &miss, Label::kNear);
+
+  __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ mov(ebx, FieldOperand(edx, HeapObject::kMapOffset));
+  __ cmp(ecx, map);

[Kevin Millikin (Chromium), 2011/11/11 10:12:34]

cmp(ecx, known_map_)

[Rico, 2011/11/15 10:12:26]

Done (and below)

+  __ j(not_equal, &miss, Label::kNear);
+  __ cmp(ebx, map);
+  __ j(not_equal, &miss, Label::kNear);
+
+  __ sub(eax, edx);
+  __ ret(0);
+
+  __ bind(&miss);
+  GenerateMiss(masm);
+}
+
+
 void ICCompareStub::GenerateMiss(MacroAssembler* masm) {
   // Save the registers.
   __ pop(ecx);

[Kevin Millikin (Chromium), 2011/11/11 10:12:34]

I'm not sure why this code is written this way, but since you're in this file,
could you clean it up a bit: there is no reason to pop the return address to
save eax and edx in the caller's frame.  Just save them on the internal frame
since there's going to be one anyway.

[Rico, 2011/11/15 10:12:26]

Done.