Add explicit transition flag to HStoreNamedField.

src/hydrogen-instructions.h

 // 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 5991 matching lines @@
   bool IsSkipWriteBarrier() const {
     return write_barrier_mode_ == SKIP_WRITE_BARRIER;
   }
 
   HValue* object() const { return OperandAt(0); }
   HValue* value() const { return OperandAt(1); }
   HValue* transition() const { return OperandAt(2); }
 
   HObjectAccess access() const { return access_; }
   HValue* new_space_dominator() const { return new_space_dominator_; }
-
-  bool has_transition() const {
-    return transition() != object();
-  }
+  bool has_transition() const { return has_transition_; }
 
   Handle<Map> transition_map() const {
     if (has_transition()) {
       return Handle<Map>::cast(HConstant::cast(transition())->handle());
     } else {
       return Handle<Map>();
     }
   }
 
   void SetTransition(HConstant* map_constant, CompilationInfo* info) {
     ASSERT(!has_transition());  // Only set once.
     Handle<Map> map = Handle<Map>::cast(map_constant->handle());
     if (map->CanBeDeprecated()) {
       map->AddDependentCompilationInfo(DependentCode::kTransitionGroup, info);
     }
     SetOperandAt(2, map_constant);
+    has_transition_ = true;
   }
 
   bool NeedsWriteBarrier() {
     ASSERT(!(FLAG_track_double_fields && field_representation().IsDouble()) ||
            !has_transition());
     if (IsSkipWriteBarrier()) return false;
     if (field_representation().IsDouble()) return false;
     if (field_representation().IsSmi()) return false;
     if (field_representation().IsInteger32()) return false;
     if (field_representation().IsExternal()) return false;
     return StoringValueNeedsWriteBarrier(value()) &&
         ReceiverObjectNeedsWriteBarrier(object(), new_space_dominator());
   }
 
   bool NeedsWriteBarrierForMap() {
     if (IsSkipWriteBarrier()) return false;
     return ReceiverObjectNeedsWriteBarrier(object(), new_space_dominator());
   }
 
   Representation field_representation() const {
     return access_.representation();
   }
 
  private:
   HStoreNamedField(HValue* obj,
                    HObjectAccess access,
                    HValue* val)
       : access_(access),
         new_space_dominator_(NULL),
-        write_barrier_mode_(UPDATE_WRITE_BARRIER) {
+        write_barrier_mode_(UPDATE_WRITE_BARRIER),
+        has_transition_(false) {
     SetOperandAt(0, obj);
     SetOperandAt(1, val);
     SetOperandAt(2, obj);
     access.SetGVNFlags(this, true);
   }
 
   HObjectAccess access_;
   HValue* new_space_dominator_;
-  WriteBarrierMode write_barrier_mode_;
+  WriteBarrierMode write_barrier_mode_ : 1;
+  bool has_transition_ : 1;
 };
 
 
 class HStoreNamedGeneric: public HTemplateInstruction<3> {
  public:
   HStoreNamedGeneric(HValue* context,
                      HValue* object,
                      Handle<String> name,
                      HValue* value,
                      StrictModeFlag strict_mode_flag)
@@ skipping 773 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_