Avoid write barrier when writing an external pointer to an internal field.

Review URL: http://codereview.chromium.org/8572003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9995 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects-inl.h

@@ -1385,6 +1385,16 @@ void JSObject::SetInternalField(int index, Object* value) {
 }
 
 
+void JSObject::SetInternalField(int index, Smi* value) {
+  ASSERT(index < GetInternalFieldCount() && index >= 0);
+  // Internal objects do follow immediately after the header, whereas in-object
+  // properties are at the end of the object. Therefore there is no need
+  // to adjust the index here.
+  int offset = GetHeaderSize() + (kPointerSize * index);
+  WRITE_FIELD(this, offset, value);
+}
+
+
 // Access fast-case object properties at index. The use of these routines
 // is needed to correctly distinguish between properties stored in-object and
 // properties stored in the properties array.

src/objects.h

@@ -1683,6 +1683,7 @@ class JSObject: public JSReceiver {
   inline int GetInternalFieldOffset(int index);
   inline Object* GetInternalField(int index);
   inline void SetInternalField(int index, Object* value);
+  inline void SetInternalField(int index, Smi* value);
 
   // The following lookup functions skip interceptors.
   void LocalLookupRealNamedProperty(String* name, LookupResult* result);