Convert String array index/length hash to BitField

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 "allocation.h"
 #include "assert-scope.h"
 #include "builtins.h"
@@ skipping 8768 matching lines @@
 
   // For strings which are array indexes the hash value has the string length
   // mixed into the hash, mainly to avoid a hash value of zero which would be
   // the case for the string '0'. 24 bits are used for the array index value.
   static const int kArrayIndexValueBits = 24;
   static const int kArrayIndexLengthBits =
       kBitsPerInt - kArrayIndexValueBits - kNofHashBitFields;
 
   STATIC_CHECK((kArrayIndexLengthBits > 0));
 
-  static const int kArrayIndexHashLengthShift =
-      kArrayIndexValueBits + kNofHashBitFields;
-
-  static const int kArrayIndexHashMask = (1 << kArrayIndexHashLengthShift) - 1;
-
-  static const int kArrayIndexValueMask =
-      ((1 << kArrayIndexValueBits) - 1) << kHashShift;
+  class ArrayIndexValueBits : public BitField<unsigned int, kNofHashBitFields,
+      kArrayIndexValueBits> {};
+  class ArrayIndexLengthBits : public BitField<unsigned int,
+      kNofHashBitFields + kArrayIndexValueBits,
+      kArrayIndexLengthBits> {};
 
   // Check that kMaxCachedArrayIndexLength + 1 is a power of two so we
   // could use a mask to test if the length of string is less than or equal to
   // kMaxCachedArrayIndexLength.
   STATIC_CHECK(IS_POWER_OF_TWO(kMaxCachedArrayIndexLength + 1));
 
   static const unsigned int kContainsCachedArrayIndexMask =
-      (~kMaxCachedArrayIndexLength << kArrayIndexHashLengthShift) |
+      (~kMaxCachedArrayIndexLength << ArrayIndexLengthBits::kShift) |
       kIsNotArrayIndexMask;
 
   // Value of empty hash field indicating that the hash is not computed.
   static const int kEmptyHashField =
       kIsNotArrayIndexMask | kHashNotComputedMask;
 
  protected:
   static inline bool IsHashFieldComputed(uint32_t field);
 
  private:
@@ skipping 2249 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_