Use the BitField class for Code::Flags.

src/objects.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 3738 matching lines @@
       InlineCacheHolderFlag holder = OWN_MAP);
 
   static inline Flags ComputeMonomorphicFlags(
       Kind kind,
       PropertyType type,
       ExtraICState extra_ic_state = kNoExtraICState,
       InlineCacheHolderFlag holder = OWN_MAP,
       InLoopFlag in_loop = NOT_IN_LOOP,
       int argc = -1);
 
-  static inline Kind ExtractKindFromFlags(Flags flags);
   static inline InlineCacheState ExtractICStateFromFlags(Flags flags);
-  static inline ExtraICState ExtractExtraICStateFromFlags(Flags flags);
   static inline InLoopFlag ExtractICInLoopFromFlags(Flags flags);
   static inline PropertyType ExtractTypeFromFlags(Flags flags);
+  static inline Kind ExtractKindFromFlags(Flags flags);
+  static inline InlineCacheHolderFlag ExtractCacheHolderFromFlags(Flags flags);
+  static inline ExtraICState ExtractExtraICStateFromFlags(Flags flags);
   static inline int ExtractArgumentsCountFromFlags(Flags flags);
-  static inline InlineCacheHolderFlag ExtractCacheHolderFromFlags(Flags flags);
+
   static inline Flags RemoveTypeFromFlags(Flags flags);
 
   // Convert a target address into a code object.
   static inline Code* GetCodeFromTargetAddress(Address address);
 
   // Convert an entry address into an object.
   static inline Object* GetObjectFromEntryAddress(Address location_of_address);
 
   // Returns the address of the first instruction.
   inline byte* instruction_start();
@@ skipping 99 matching lines @@
   static const int kToBooleanTypeOffset = kStubMajorKeyOffset + 1;
   static const int kHasDeoptimizationSupportOffset = kOptimizableOffset + 1;
 
   static const int kBinaryOpReturnTypeOffset = kBinaryOpTypeOffset + 1;
   static const int kAllowOSRAtLoopNestingLevelOffset =
       kHasDeoptimizationSupportOffset + 1;
 
   static const int kSafepointTableOffsetOffset = kStackSlotsOffset + kIntSize;
   static const int kStackCheckTableOffsetOffset = kStackSlotsOffset + kIntSize;
 
-  // Flags layout.
-  static const int kFlagsICStateShift        = 0;
-  static const int kFlagsICInLoopShift       = 3;
-  static const int kFlagsTypeShift           = 4;
-  static const int kFlagsKindShift           = 8;
-  static const int kFlagsICHolderShift       = 12;
-  static const int kFlagsExtraICStateShift   = 13;
+  // Flags layout.  BitField<type, shift, size>.
+  class ICStateField: public BitField<InlineCacheState, 0, 3> {};
+  class ICInLoopField: public BitField<InLoopFlag, 3, 1> {};
+  class TypeField: public BitField<PropertyType, 4, 4> {};
+  class KindField: public BitField<Kind, 8, 4> {};
+  class CacheHolderField: public BitField<InlineCacheHolderFlag, 12, 1> {};
+  class ExtraICStateField: public BitField<ExtraICState, 13, 2> {};
+
+  // Signed field cannot be encoded using the BitField class.
   static const int kFlagsArgumentsCountShift = 15;
-
-  static const int kFlagsICStateMask        = 0x00000007;  // 00000000111
-  static const int kFlagsICInLoopMask       = 0x00000008;  // 00000001000
-  static const int kFlagsTypeMask           = 0x000000F0;  // 00001110000
-  static const int kFlagsKindMask           = 0x00000F00;  // 11110000000
-  static const int kFlagsCacheInPrototypeMapMask = 0x00001000;
-  static const int kFlagsExtraICStateMask   = 0x00006000;
-  static const int kFlagsArgumentsCountMask = 0xFFFF8000;
+  static const int kFlagsArgumentsCountMask = 0xffff8000;
 
   static const int kFlagsNotUsedInLookup =
-      (kFlagsICInLoopMask | kFlagsTypeMask | kFlagsCacheInPrototypeMapMask);
+      ICInLoopField::kMask | TypeField::kMask | CacheHolderField::kMask;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Code);
 };
 
 
 // All heap objects have a Map that describes their structure.
 //  A Map contains information about:
 //  - Size information about the object
 //  - How to iterate over an object (for garbage collection)
@@ skipping 3541 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_