Don't replace initializing smi stores during store elimination.

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include "v8.h"
 
 #include "allocation.h"
@@ skipping 6735 matching lines @@
   }
 
   Representation field_representation() const {
     return access_.representation();
   }
 
   void UpdateValue(HValue* value) {
     SetOperandAt(1, value);
   }
 
+  bool CanBeReplacedWith(HStoreNamedField* that) const {
+    if (!this->access().Equals(that->access())) return false;
+    if (SmiValuesAre32Bits() &&
+        this->field_representation().IsSmi() &&
+        this->store_mode() == INITIALIZING_STORE &&
+        that->store_mode() == STORE_TO_INITIALIZED_ENTRY) {
+      // We cannot replace an initializing store to a smi field with a store to
+      // an initialized entry on 64-bit architectures (with 32-bit smis).
+      return false;
+    }
+    return true;
+  }
+
  private:
   HStoreNamedField(HValue* obj,
                    HObjectAccess access,
                    HValue* val,
                    StoreFieldOrKeyedMode store_mode = INITIALIZING_STORE)
       : access_(access),
         new_space_dominator_(NULL),
         has_transition_(false),
         store_mode_(store_mode) {
     // Stores to a non existing in-object property are allowed only to the
@@ skipping 946 matching lines @@
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_