Remove extranous holder load in some prototype-chain checking cases

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 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 5397 matching lines @@
   // smi
   __ bind(&is_smi);
   __ SmiUntag(input_reg);
   __ ClampUint8(input_reg);
 
   __ bind(&done);
 }
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
-  ASSERT(instr->temp()->Equals(instr->result()));
   Register reg = ToRegister(instr->temp());
 
   ZoneList<Handle<JSObject> >* prototypes = instr->prototypes();
   ZoneList<Handle<Map> >* maps = instr->maps();
 
   ASSERT(prototypes->length() == maps->length());
 
-  // TODO(ulan): Move this check to hydrogen and split HCheckPrototypeMaps
-  // into two instruction: one that checks the prototypes and another that
-  // loads the holder (HConstant). Find a way to do it without breaking
-  // parallel recompilation.
   if (instr->hydrogen()->CanOmitPrototypeChecks()) {
     for (int i = 0; i < maps->length(); i++) {
       prototype_maps_.Add(maps->at(i), info()->zone());
     }
-    __ LoadHeapObject(reg, prototypes->at(prototypes->length() - 1));
   } else {
     for (int i = 0; i < prototypes->length(); i++) {
       __ LoadHeapObject(reg, prototypes->at(i));
       DoCheckMapCommon(reg, maps->at(i), ALLOW_ELEMENT_TRANSITION_MAPS, instr);
     }
   }
 }
 
 
 void LCodeGen::DoAllocateObject(LAllocateObject* instr) {
@@ skipping 847 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32