[heap] Don't clear black areas when deserializing, they will be marked black later anyway.

src/heap/heap.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_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 432 matching lines @@
 };
 
 
 enum ArrayStorageAllocationMode {
   DONT_INITIALIZE_ARRAY_ELEMENTS,
   INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE
 };
 
 enum class ClearRecordedSlots { kYes, kNo };
 
+enum class ClearBlackArea { kYes, kNo };
+
 class Heap {
  public:
   // Declare all the root indices.  This defines the root list order.
   enum RootListIndex {
 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
 #undef ROOT_INDEX_DECLARATION
 
 #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex,
         INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION)
@@ skipping 203 matching lines @@
   // FreeSpace objects have a null map after deserialization. Update the map.
   void RepairFreeListsAfterDeserialization();
 
   // Move len elements within a given array from src_index index to dst_index
   // index.
   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. If slots could have been recorded in
   // the freed area, then pass ClearRecordedSlots::kYes as the mode. Otherwise,
-  // pass ClearRecordedSlots::kNo.
-  void CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots mode);
+  // pass ClearRecordedSlots::kNo. If the filler was created in a black area
+  // we may want to clear the corresponding mark bits with ClearBlackArea::kYes,
+  // which is the default. ClearBlackArea::kNo does not clear the mark bits.
+  void CreateFillerObjectAt(
+      Address addr, int size, ClearRecordedSlots mode,
+      ClearBlackArea black_area_mode = ClearBlackArea::kYes);
 
   bool CanMoveObjectStart(HeapObject* object);
 
   // Maintain consistency of live bytes during incremental marking.
   void AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode);
 
   // Trim the given array from the left. Note that this relocates the object
   // start and hence is only valid if there is only a single reference to it.
   FixedArrayBase* LeftTrimFixedArray(FixedArrayBase* obj, int elements_to_trim);
 
@@ skipping 2023 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_