Move field index into property details, freeing up the value slot of fields.

src/property-details.h

 // Copyright 2012 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 151 matching lines @@
     value_ = TypeField::encode(type)
         | AttributesField::encode(attributes)
         | DictionaryStorageField::encode(index);
 
     ASSERT(type == this->type());
     ASSERT(attributes == this->attributes());
   }
 
   PropertyDetails(PropertyAttributes attributes,
                   PropertyType type,
-                  Representation representation) {
+                  Representation representation,
+                  int field_index = 0) {
     value_ = TypeField::encode(type)
         | AttributesField::encode(attributes)
-        | RepresentationField::encode(EncodeRepresentation(representation));
+        | RepresentationField::encode(EncodeRepresentation(representation))
+        | FieldIndexField::encode(field_index);
   }
 
   int pointer() { return DescriptorPointer::decode(value_); }
 
   PropertyDetails set_pointer(int i) { return PropertyDetails(value_, i); }
 
   PropertyDetails CopyWithRepresentation(Representation representation) {
     return PropertyDetails(value_, representation);
   }
   PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) {
@@ skipping 21 matching lines @@
   }
 
   int dictionary_index() {
     return DictionaryStorageField::decode(value_);
   }
 
   Representation representation() {
     return DecodeRepresentation(RepresentationField::decode(value_));
   }
 
+  int  field_index() {
+    return FieldIndexField::decode(value_);
+  }
+
   inline PropertyDetails AsDeleted();
 
   static bool IsValidIndex(int index) {
     return DictionaryStorageField::is_valid(index);
   }
 
   bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
   bool IsDontDelete() const { return (attributes() & DONT_DELETE) != 0; }
   bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
   bool IsDeleted() const { return DeletedField::decode(value_) != 0;}
 
   // Bit fields in value_ (type, shift, size). Must be public so the
   // constants can be embedded in generated code.
   class TypeField:                public BitField<PropertyType,       0,  3> {};
   class AttributesField:          public BitField<PropertyAttributes, 3,  3> {};
   class DeletedField:             public BitField<uint32_t,           6,  1> {};

[Jakob Kummerow, 2013/05/31 16:44:14]

How about separating the groups of BitFields that are used for various property
types by appropriate comments?

   class DictionaryStorageField:   public BitField<uint32_t,           7, 24> {};
-  class DescriptorPointer:        public BitField<uint32_t,           7, 11> {};
-  class RepresentationField:      public BitField<uint32_t,          18,  3> {};
+  class DescriptorPointer:        public BitField<uint32_t,           6, 11> {};
+  class RepresentationField:      public BitField<uint32_t,          17,  3> {};
+  class FieldIndexField:          public BitField<uint32_t,          20, 11> {};
 
   static const int kInitialIndex = 1;
 
  private:
   PropertyDetails(int value, int pointer) {
     value_ = DescriptorPointer::update(value, pointer);
   }
   PropertyDetails(int value, Representation representation) {
     value_ = RepresentationField::update(
         value, EncodeRepresentation(representation));
   }
   PropertyDetails(int value, PropertyAttributes attributes) {
     value_ = AttributesField::update(value, attributes);
   }
 
   uint32_t value_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_