Filter invalid slots out from the SlotsBuffer after marking.

src/heap/mark-compact.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_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include "src/base/bits.h"
 #include "src/heap/spaces.h"
 
@@ skipping 345 matching lines @@
     buffer->Add(slot);
     return true;
   }
 
   static bool IsTypedSlot(ObjectSlot slot);
 
   static bool AddTo(SlotsBufferAllocator* allocator,
                     SlotsBuffer** buffer_address, SlotType type, Address addr,
                     AdditionMode mode);
 
+  // Eliminates all stale entries from the slots buffer, i.e., slots that
+  // are not part of live objects anymore. This method must be called after
+  // marking, when the whole transitive closure is known and must be called
+  // before sweeping when mark bits are still intact.
+  static void RemoveInvalidSlots(Heap* heap, SlotsBuffer* buffer);
+
+  // Ensures that there are no invalid slots in the chain of slots buffers.
+  static void VerifySlots(Heap* heap, SlotsBuffer* buffer);
+
   static const int kNumberOfElements = 1021;
 
  private:
   static const int kChainLengthThreshold = 15;
 
   intptr_t idx_;
   intptr_t chain_length_;
   SlotsBuffer* next_;
   ObjectSlot slots_[kNumberOfElements];
 };
@@ skipping 275 matching lines @@
 
   void EnsureMarkingDequeIsCommittedAndInitialize();
 
   void InitializeMarkingDeque();
 
   void UncommitMarkingDeque();
 
   // The following four methods can just be called after marking, when the
   // whole transitive closure is known. They must be called before sweeping
   // when mark bits are still intact.
-  bool IsSlotInBlackObject(Page* p, Address slot);
+  bool IsSlotInBlackObject(Page* p, Address slot, HeapObject** out_object);
   bool IsSlotInBlackObjectSlow(Page* p, Address slot);
-  bool IsSlotInLiveObject(HeapObject** address, HeapObject* object);
-  void VerifyIsSlotInLiveObject(HeapObject** address, HeapObject* object);
+  bool IsSlotInLiveObject(Address slot);
+  void VerifyIsSlotInLiveObject(Address slot, HeapObject* object);
 
  private:
   class SweeperTask;
 
   explicit MarkCompactCollector(Heap* heap);
   ~MarkCompactCollector();
 
   bool MarkInvalidatedCode();
   bool WillBeDeoptimized(Code* code);
   void RemoveDeadInvalidatedCode();
   void ProcessInvalidatedCode(ObjectVisitor* visitor);
   void EvictEvacuationCandidate(Page* page);
+  void ClearInvalidSlotsBufferEntries(PagedSpace* space);
+  void ClearInvalidStoreAndSlotsBufferEntries();
 
   void StartSweeperThreads();
 
 #ifdef DEBUG
   enum CollectorState {
     IDLE,
     PREPARE_GC,
     MARK_LIVE_OBJECTS,
     SWEEP_SPACES,
     ENCODE_FORWARDING_ADDRESSES,
@@ skipping 260 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_MARK_COMPACT_H_