Optimize the equality check case of ICCompare stubs.

src/ia32/code-stubs-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6484 matching lines @@
 
   ASSERT(GetCondition() == equal);
   __ sub(eax, edx);
   __ ret(0);
 
   __ bind(&miss);
   GenerateMiss(masm);
 }
 
 
+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.

   __ push(edx);
   __ push(eax);
   __ push(ecx);
 
   {
     // Call the runtime system in a fresh internal frame.
     ExternalReference miss = ExternalReference(IC_Utility(IC::kCompareIC_Miss),
                                                masm->isolate());
     FrameScope scope(masm, StackFrame::INTERNAL);
     __ push(edx);
@@ skipping 593 matching lines @@
     __ bind(&element_done);
     __ ret(0);
   }
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32