Synchronize store buffer processing and concurrent sweeping.

src/heap.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 1456 matching lines @@
   void TracePathToObjectFrom(Object* target, Object* root);
   void TracePathToObject(Object* target);
   void TracePathToGlobal();
 #endif
 
   // Callback function passed to Heap::Iterate etc.  Copies an object if
   // necessary, the object might be promoted to an old space.  The caller must
   // ensure the precondition that the object is (a) a heap object and (b) in
   // the heap's from space.
   static inline void ScavengePointer(HeapObject** p);
-  static inline void ScavengeObject(HeapObject** p, HeapObject* object);
+
+  // p is the slot pointing to the object in new space
+  // object ist the object in new space
+  // old_object is not used in the ScavengeObject callback
+  static inline void ScavengeObject(HeapObject** p,
+                                    HeapObject* object,
+                                    Object* old_object = NULL);
 
   enum ScratchpadSlotMode {
     IGNORE_SCRATCHPAD_SLOT,
     RECORD_SCRATCHPAD_SLOT
   };
 
   // An object may have an AllocationSite associated with it through a trailing
   // AllocationMemento. Its feedback should be updated when objects are found
   // in the heap.
   static inline void UpdateAllocationSiteFeedback(
@@ skipping 1596 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_