Turn JSArrayBuffer::flags into a bit field

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 10224 matching lines @@
 
 
 class JSArrayBuffer: public JSObject {
  public:
   // [backing_store]: backing memory for this array
   DECL_ACCESSORS(backing_store, void)
 
   // [byte_length]: length in bytes
   DECL_ACCESSORS(byte_length, Object)
 
-  // [flags]
-  DECL_ACCESSORS(flag, Smi)
+  inline uint32_t bit_field() const;
+  inline void set_bit_field(uint32_t bits);
 
   inline bool is_external();
   inline void set_is_external(bool value);
 
   inline bool should_be_freed();
   inline void set_should_be_freed(bool value);
 
   inline bool is_neuterable();
   inline void set_is_neuterable(bool value);
 
   inline bool was_neutered();
   inline void set_was_neutered(bool value);
 
   // [weak_next]: linked list of array buffers.
   DECL_ACCESSORS(weak_next, Object)
 
   DECLARE_CAST(JSArrayBuffer)
 
   void Neuter();
 
   // Dispatched behavior.
   DECLARE_PRINTER(JSArrayBuffer)
   DECLARE_VERIFIER(JSArrayBuffer)
 
   static const int kBackingStoreOffset = JSObject::kHeaderSize;
   static const int kByteLengthOffset = kBackingStoreOffset + kPointerSize;
-  static const int kFlagOffset = kByteLengthOffset + kPointerSize;
-  static const int kWeakNextOffset = kFlagOffset + kPointerSize;
+  static const int kBitFieldOffset = kByteLengthOffset + kPointerSize;
+  static const int kWeakNextOffset = kBitFieldOffset + kPointerSize;
   static const int kSize = kWeakNextOffset + kPointerSize;
 
   static const int kSizeWithInternalFields =
       kSize + v8::ArrayBuffer::kInternalFieldCount * kPointerSize;
 
-  // Bit position in a flag
-  static const int kIsExternalBit = 0;
-  static const int kShouldBeFreed = 1;
-  static const int kIsNeuterableBit = 2;
-  static const int kWasNeuteredBit = 3;
+  class IsExternal : public BitField<bool, 1, 1> {};
+  class ShouldBeFreed : public BitField<bool, 2, 1> {};
+  class IsNeuterable : public BitField<bool, 3, 1> {};
+  class WasNeutered : public BitField<bool, 4, 1> {};
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSArrayBuffer);
 };
 
 
 class JSArrayBufferView: public JSObject {
  public:
   // [buffer]: ArrayBuffer that this typed array views.
   DECL_ACCESSORS(buffer, Object)
@@ skipping 808 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_