Clear recorded slots when creating filler objects.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 4a76777ecd06727983709105fdc1439acb2515b8..b6f09e2f81a0bffb07049f56a2b104020c4438c3 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -403,6 +403,7 @@ enum ArrayStorageAllocationMode {
   INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE
 };
 
+enum RecordedSlotsMode { kClearRecordedSlots, kNoRecordedSlots };

[jochen (gone - plz use gerrit), 2016/02/25 13:49:57]

what about making this an enum class? enum class ClearRecordSlots { kYes, kNo }.
Callsites would be more readable then imo

[ulan, 2016/02/25 14:05:14]

Nice trick! Done.

 
 class Heap {
  public:
@@ -632,8 +633,10 @@ class Heap {
   void MoveElements(FixedArray* array, int dst_index, int src_index, int len);
 
   // Initialize a filler object to keep the ability to iterate over the heap
-  // when introducing gaps within pages.
-  void CreateFillerObjectAt(Address addr, int size);
+  // when introducing gaps within pages. If slots could have been recorded in
+  // the freed area, then pass kClearRecordedSlots as the mode. Otherwise,
+  // pass kNoRecordedSlots.
+  void CreateFillerObjectAt(Address addr, int size, RecordedSlotsMode mode);
 
   bool CanMoveObjectStart(HeapObject* object);
 
@@ -1060,7 +1063,7 @@ class Heap {
   }
 
   void ClearRecordedSlot(HeapObject* object, Object** slot);
-  void ClearRecordedSlotRange(HeapObject* object, Object** start, Object** end);
+  void ClearRecordedSlotRange(Address start, Address end);
 
   // ===========================================================================
   // Incremental marking API. ==================================================