In-object double fields unboxing (for 64-bit only).

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 <iosfwd>
 
 #include "src/v8.h"
@@ skipping 6869 matching lines @@
   }
 
   void SetTransition(HConstant* transition) {
     DCHECK(!has_transition());  // Only set once.
     SetOperandAt(2, transition);
     has_transition_ = true;
     SetChangesFlag(kMaps);
   }
 
   bool NeedsWriteBarrier() const {
-    DCHECK(!field_representation().IsDouble() || !has_transition());
+    DCHECK(!field_representation().IsDouble() ||
+           (FLAG_unbox_double_fields && access_.IsInobject()) ||
+           !has_transition());
     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(), value(), dominator());
   }
 
   bool NeedsWriteBarrierForMap() {
     return ReceiverObjectNeedsWriteBarrier(object(), transition(),
@@ skipping 1005 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_