Eliminate write barrier for global stores at compile time if value stored is a smi.

src/x64/lithium-x64.h

 // Copyright 2011 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 1242 matching lines @@
     inputs_[1] = value;
     temps_[0] = temp;
   }
 
   DECLARE_CONCRETE_INSTRUCTION(StoreContextSlot, "store-context-slot")
   DECLARE_HYDROGEN_ACCESSOR(StoreContextSlot)
 
   LOperand* context() { return InputAt(0); }
   LOperand* value() { return InputAt(1); }
   int slot_index() { return hydrogen()->slot_index(); }
-  int needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
 
   virtual void PrintDataTo(StringStream* stream);
 };
 
 
 class LPushArgument: public LTemplateInstruction<0, 1, 0> {
  public:
   explicit LPushArgument(LOperand* value) {
     inputs_[0] = value;
   }
@@ skipping 270 matching lines @@
   DECLARE_HYDROGEN_ACCESSOR(StoreNamedField)
 
   virtual void PrintDataTo(StringStream* stream);
 
   LOperand* object() { return inputs_[0]; }
   LOperand* value() { return inputs_[1]; }
 
   Handle<Object> name() const { return hydrogen()->name(); }
   bool is_in_object() { return hydrogen()->is_in_object(); }
   int offset() { return hydrogen()->offset(); }
-  bool needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
   Handle<Map> transition() const { return hydrogen()->transition(); }
 };
 
 
 class LStoreNamedGeneric: public LTemplateInstruction<0, 2, 0> {
  public:
   LStoreNamedGeneric(LOperand* object, LOperand* value) {
     inputs_[0] = object;
     inputs_[1] = value;
   }
@@ skipping 612 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_