MarkBit cleanup: They have to be accessed through Marking accessors.

src/heap/spaces.h

 // Copyright 2011 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_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 86 matching lines @@
 class Space;
 class FreeList;
 class MemoryChunk;
 
 class MarkBit {
  public:
   typedef uint32_t CellType;
 
   inline MarkBit(CellType* cell, CellType mask) : cell_(cell), mask_(mask) {}
 
-  inline CellType* cell() { return cell_; }
-  inline CellType mask() { return mask_; }
-
 #ifdef DEBUG
   bool operator==(const MarkBit& other) {
     return cell_ == other.cell_ && mask_ == other.mask_;
   }
 #endif
 
-  inline void Set() { *cell_ |= mask_; }
-  inline bool Get() { return (*cell_ & mask_) != 0; }
-  inline void Clear() { *cell_ &= ~mask_; }
-
+ private:
+  inline CellType* cell() { return cell_; }
+  inline CellType mask() { return mask_; }
 
   inline MarkBit Next() {
     CellType new_mask = mask_ << 1;
     if (new_mask == 0) {
       return MarkBit(cell_ + 1, 1);
     } else {
       return MarkBit(cell_, new_mask);
     }
   }
 
- private:
+  inline void Set() { *cell_ |= mask_; }
+  inline bool Get() { return (*cell_ & mask_) != 0; }
+  inline void Clear() { *cell_ &= ~mask_; }
+
   CellType* cell_;
   CellType mask_;
+
+  friend class Marking;
 };
 
 
 // Bitmap is a sequence of cells each containing fixed number of bits.
 class Bitmap {
  public:
   static const uint32_t kBitsPerCell = 32;
   static const uint32_t kBitsPerCellLog2 = 5;
   static const uint32_t kBitIndexMask = kBitsPerCell - 1;
   static const uint32_t kBytesPerCell = kBitsPerCell / kBitsPerByte;
@@ skipping 2717 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_