A very small marking bitmap (2 bits) is sufficient for large object page since just one object in i…

src/spaces-inl.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 21 matching lines @@
 #include "spaces.h"
 #include "v8memory.h"
 
 namespace v8 {
 namespace internal {
 
 
 // -----------------------------------------------------------------------------
 // Bitmap
 
+int Bitmap::CellsCount() {
+  MemoryChunk* chunk = MemoryChunk::FromAddress(address());
+  ASSERT(chunk->is_valid());
+  size_t rLength = (chunk->area_start() - address()) << kBitsPerByteLog2;
+  if (rLength > kLength) rLength = kLength;
+  rLength &= ~(kBitsPerCell - 1);
+  return CellsForLength(rLength);
+}
+
 void Bitmap::Clear(MemoryChunk* chunk) {
   Bitmap* bitmap = chunk->markbits();
   for (int i = 0; i < bitmap->CellsCount(); i++) bitmap->cells()[i] = 0;
   chunk->ResetLiveBytes();
 }
 
 
 // -----------------------------------------------------------------------------
 // PageIterator
 
@@ skipping 287 matching lines @@
   Map* map = object->map();
   Heap* heap = object->GetHeap();
   return map == heap->raw_unchecked_free_space_map()
       || map == heap->raw_unchecked_one_pointer_filler_map()
       || map == heap->raw_unchecked_two_pointer_filler_map();
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_INL_H_