Push version 2.5.7 to trunk....

src/heap.h

 // Copyright 2010 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 1540 matching lines @@
   int counter_;
 };
 
 
 // Space iterator for iterating over all spaces of the heap.
 // For each space an object iterator is provided. The deallocation of the
 // returned object iterators is handled by the space iterator.
 class SpaceIterator : public Malloced {
  public:
   SpaceIterator();
+  explicit SpaceIterator(HeapObjectCallback size_func);
   virtual ~SpaceIterator();
 
   bool has_next();
   ObjectIterator* next();
 
  private:
   ObjectIterator* CreateIterator();
 
   int current_space_;  // from enum AllocationSpace.
   ObjectIterator* iterator_;  // object iterator for the current space.
+  HeapObjectCallback size_func_;
 };
 
 
-// A HeapIterator provides iteration over the whole heap It aggregates a the
-// specific iterators for the different spaces as these can only iterate over
-// one space only.
+// A HeapIterator provides iteration over the whole heap. It
+// aggregates the specific iterators for the different spaces as
+// these can only iterate over one space only.
+//
+// HeapIterator can skip free list nodes (that is, de-allocated heap
+// objects that still remain in the heap). As implementation of free
+// nodes filtering uses GC marks, it can't be used during MS/MC GC
+// phases. Also, it is forbidden to interrupt iteration in this mode,
+// as this will leave heap objects marked (and thus, unusable).
+class FreeListNodesFilter;
 
 class HeapIterator BASE_EMBEDDED {
  public:
-  explicit HeapIterator();
-  virtual ~HeapIterator();
+  enum FreeListNodesFiltering {
+    kNoFiltering,
+    kPreciseFiltering
+  };
+
+  HeapIterator();
+  explicit HeapIterator(FreeListNodesFiltering filtering);
+  ~HeapIterator();
 
   HeapObject* next();
   void reset();
 
  private:
   // Perform the initialization.
   void Init();
-
   // Perform all necessary shutdown (destruction) work.
   void Shutdown();
+  HeapObject* NextObject();
 
+  FreeListNodesFiltering filtering_;
+  FreeListNodesFilter* filter_;
   // Space iterator for iterating all the spaces.
   SpaceIterator* space_iterator_;
   // Object iterator for the space currently being iterated.
   ObjectIterator* object_iterator_;
 };
 
 
 // Cache for mapping (map, property name) into field offset.
 // Cleared at startup and prior to mark sweep collection.
 class KeyedLookupCache {
@@ skipping 482 matching lines @@
   // Return whether this object should be retained. If NULL is returned the
   // object has no references. Otherwise the address of the retained object
   // should be returned as in some GC situations the object has been moved.
   virtual Object* RetainAs(Object* object) = 0;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_