Use the BitField class for Code::Flags.

src/utils.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 185 matching lines @@
   return static_cast<int>(length);
 }
 
 
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.
 template<class T, int shift, int size>
 class BitField {
  public:
+  // A uint32_t mask of bit field.  To use all bits of a uint32 in a
+  // bitfield without compiler warnings we have to compute 2^32 without
+  // using a shift count of 32.
+  static const uint32_t kMask = ((1U << shift) << size) - (1U << shift);
+
+  // Value for the field with all bits set.
+  static const T kMax = static_cast<T>((1U << size) - 1);
+
   // Tells whether the provided value fits into the bit field.
   static bool is_valid(T value) {
-    return (static_cast<uint32_t>(value) & ~((1U << (size)) - 1)) == 0;
-  }
-
-  // Returns a uint32_t mask of bit field.
-  static uint32_t mask() {
-    // To use all bits of a uint32 in a bitfield without compiler warnings we
-    // have to compute 2^32 without using a shift count of 32.
-    return ((1U << shift) << size) - (1U << shift);
+    return (static_cast<uint32_t>(value) & ~kMax) == 0;
   }
 
   // Returns a uint32_t with the bit field value encoded.
   static uint32_t encode(T value) {
     ASSERT(is_valid(value));
     return static_cast<uint32_t>(value) << shift;
   }
 
   // Returns a uint32_t with the bit field value updated.
   static uint32_t update(uint32_t previous, T value) {
-    return (previous & ~mask()) | encode(value);
+    return (previous & ~kMask) | encode(value);
   }
 
   // Extracts the bit field from the value.
   static T decode(uint32_t value) {
-    return static_cast<T>((value & mask()) >> shift);
-  }
-
-  // Value for the field with all bits set.
-  static T max() {
-    return decode(mask());
+    return static_cast<T>((value & kMask) >> shift);
   }
 };
 
 
 // ----------------------------------------------------------------------------
 // Hash function.
 
 // Thomas Wang, Integer Hash Functions.
 // http://www.concentric.net/~Ttwang/tech/inthash.htm
 static inline uint32_t ComputeIntegerHash(uint32_t key) {
@@ skipping 668 matching lines @@
     ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT));
     return 1 << element;
   }
 
   T bits_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_