Introduce lazy sweeping.

src/incremental-marking.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 24 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 
 // TODO(gc) rename into IncrementalMarker after merge.
 class IncrementalMarking : public AllStatic {
  public:
   enum State {
     STOPPED,
+    SWEEPING,
     MARKING,
     COMPLETE
   };
 
   explicit IncrementalMarking(Heap* heap);
 
   State state() {
     ASSERT(state_ == STOPPED || FLAG_incremental_marking);
     return state_;
   }
 
   bool should_hurry() { return should_hurry_; }
 
   inline bool IsStopped() { return state() == STOPPED; }
 
-  inline bool IsMarking() { return state() == MARKING; }
+  inline bool IsMarking() { return state() >= MARKING; }
+
+  inline bool IsMarkingIncomplete() { return state() == MARKING; }
 
   bool WorthActivating();
 
   void Start();
 
   void Stop();
 
   void PrepareForScavenge();
 
   void UpdateMarkingDequeAfterScavenge();
 
   void Hurry();
 
   void Finalize();
 
+  void Abort();
+
   void MarkingComplete();
 
   // It's hard to know how much work the incremental marker should do to make
   // progress in the face of the mutator creating new work for it.  We start
   // of at a moderate rate of work and gradually increase the speed of the
   // incremental marker until it completes.
   // Do some marking every time this much memory has been allocated.
   static const intptr_t kAllocatedThreshold = 8192;
   // Start off by marking this many times more memory than has been allocated.
   static const intptr_t kInitialAllocationMarkingFactor = 4;
@@ skipping 102 matching lines @@
   void set_should_hurry(bool val) {
     should_hurry_ = val;
   }
 
   void ResetStepCounters() {
     steps_count_ = 0;
     steps_took_ = 0;
     allocation_marking_factor_ = kInitialAllocationMarkingFactor;
   }
 
+  static void ClearMarkbits(PagedSpace* space);
+  void ClearMarkbits();
+
+#ifdef DEBUG
+  void VerifyMarkbitsAreClean();
+  static void VerifyMarkbitsAreClean(PagedSpace* space);
+#endif
+
+  void StartMarking();
+
 
   Heap* heap_;
 
   State state_;
   MarkingDeque marking_deque_;
 
   int steps_count_;
   double steps_took_;
   bool should_hurry_;
   intptr_t allocation_marking_factor_;
   intptr_t allocated_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_INCREMENTAL_MARKING_H_