Avoid handle dereference during graph optimization.

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 4114 matching lines @@
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }
 
 
 void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
   Register object_reg = ToRegister(instr->object());
   Register new_map_reg = ToRegister(instr->new_map_temp());
 
   Handle<Map> from_map = instr->original_map();
   Handle<Map> to_map = instr->transitioned_map();
-  ElementsKind from_kind = from_map->elements_kind();
-  ElementsKind to_kind = to_map->elements_kind();
+  ElementsKind from_kind = instr->from_kind();
+  ElementsKind to_kind = instr->to_kind();
 
   Label not_applicable;
   __ Cmp(FieldOperand(object_reg, HeapObject::kMapOffset), from_map);
   __ j(not_equal, &not_applicable);
   __ movq(new_map_reg, to_map, RelocInfo::EMBEDDED_OBJECT);
   if (IsSimpleMapChangeTransition(from_kind, to_kind)) {
     __ movq(FieldOperand(object_reg, HeapObject::kMapOffset), new_map_reg);
     // Write barrier.
     ASSERT_NE(instr->temp(), NULL);
     __ RecordWriteField(object_reg, HeapObject::kMapOffset, new_map_reg,
@@ skipping 1420 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64