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

src/spaces.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 165 matching lines @@
     (1 << kPageSizeBits) >> (kPointerSizeLog2);
 
   static const size_t kSize =
     (1 << kPageSizeBits) >> (kPointerSizeLog2 + kBitsPerByteLog2);
 
 
   static int CellsForLength(int length) {
     return (length + kBitsPerCell - 1) >> kBitsPerCellLog2;
   }
 
-  int CellsCount() {
-    return CellsForLength(kLength);
-  }
+  INLINE(int CellsCount());
 
   static int SizeFor(int cells_count) {
     return sizeof(MarkBit::CellType) * cells_count;
   }
 
   INLINE(static uint32_t IndexToCell(uint32_t index)) {
     return index >> kBitsPerCellLog2;
   }
 
   INLINE(static uint32_t CellToIndex(uint32_t index)) {
@@ skipping 295 matching lines @@
   static const int kBodyOffset =
     CODE_POINTER_ALIGN(MAP_POINTER_ALIGN(kHeaderSize + Bitmap::kSize));
 
   // The start offset of the object area in a page. Aligned to both maps and
   // code alignment to be suitable for both.  Also aligned to 32 words because
   // the marking bitmap is arranged in 32 bit chunks.
   static const int kObjectStartAlignment = 32 * kPointerSize;
   static const int kObjectStartOffset = kBodyOffset - 1 +
       (kObjectStartAlignment - (kBodyOffset - 1) % kObjectStartAlignment);
 
+  static const int kLargeObjectBodyOffset =
+      CODE_POINTER_ALIGN(MAP_POINTER_ALIGN(kHeaderSize + kPointerSize));
+  static const int kLargeObjectStartOffset =
+      kObjectStartAlignment + (kLargeObjectBodyOffset - 1) -
+      (kLargeObjectBodyOffset - 1) % kObjectStartAlignment;
+
   size_t size() const { return size_; }
 
   void set_size(size_t size) {
     size_ = size;
   }
 
   void SetArea(Address area_start, Address area_end) {
     area_start_ = area_start;
     area_end_ = area_end;
   }
@@ skipping 2125 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_