Improve handling of property loads on the proto chain.

src/x64/lithium-codegen-x64.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 4519 matching lines @@
   // smi
   __ bind(&is_smi);
   __ SmiToInteger32(input_reg, input_reg);
   __ ClampUint8(input_reg);
 
   __ bind(&done);
 }
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register reg = ToRegister(instr->temp());
 
   Handle<JSObject> holder = instr->holder();
   Handle<JSObject> current_prototype = instr->prototype();
 
   // Load prototype object.
   __ LoadHeapObject(reg, current_prototype);
 
   // Check prototype maps up to the holder.
   while (!current_prototype.is_identical_to(holder)) {
@@ skipping 761 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64