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

src/spaces-inl.h

Index: src/spaces-inl.h
===================================================================
--- src/spaces-inl.h	(revision 11322)
+++ src/spaces-inl.h	(working copy)
@@ -39,6 +39,15 @@
 // -----------------------------------------------------------------------------
 // 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;