Support slots recording for compaction during incremental marking.

src/mark-compact.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 247 matching lines @@
 
 class SlotsBuffer {
  public:
   typedef Object** ObjectSlot;
 
   SlotsBuffer();
   ~SlotsBuffer();
 
   void Clear();
   void Add(ObjectSlot slot);
-  void Iterate(ObjectVisitor* visitor);
+  void Update();
   void Report();
 
  private:
   static const int kBufferSize = 1024;
 
   List<ObjectSlot*> buffers_;
   ObjectSlot* buffer_;
 
   int idx_;
   int buffer_idx_;
@@ skipping 47 matching lines @@
 
   void AddEvacuationCandidate(Page* p);
 
   // Prepares for GC by resetting relocation info in old and map spaces and
   // choosing spaces to compact.
   void Prepare(GCTracer* tracer);
 
   // Performs a global garbage collection.
   void CollectGarbage();
 
+  bool StartCompaction();
+
   // During a full GC, there is a stack-allocated GCTracer that is used for
   // bookkeeping information.  Return a pointer to that tracer.
   GCTracer* tracer() { return tracer_; }
 
 #ifdef DEBUG
   // Checks whether performing mark-compact collection.
   bool in_use() { return state_ > PREPARE_GC; }
   bool are_map_pointers_encoded() { return state_ == UPDATE_POINTERS; }
 #endif
 
@@ skipping 63 matching lines @@
   };
 
   // The current stage of the collector.
   CollectorState state_;
 #endif
 
   // Global flag that forces sweeping to be precise, so we can traverse the
   // heap.
   bool sweep_precisely_;
 
+  // True if we are collecting slots to perform evacuation from evacuation
+  // candidates.
+  bool compacting_;
+
   // A pointer to the current stack-allocated GC tracer object during a full
   // collection (NULL before and after).
   GCTracer* tracer_;
 
   SlotsBuffer slots_buffer_;
 
   // Finishes GC, performs heap verification if enabled.
   void Finish();
 
   // -----------------------------------------------------------------------
@@ skipping 164 matching lines @@
 
   List<Page*> evacuation_candidates_;
 
   friend class Heap;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_