Track representations 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 58 matching lines @@
   CALLBACKS                 = 3,
   // Only in lookup results, not in descriptors.
   HANDLER                   = 4,
   INTERCEPTOR               = 5,
   TRANSITION                = 6,
   // Only used as a marker in LookupResult.
   NONEXISTENT               = 7
 };
 
 
+enum StorageType {
+  TAGGED                    = 0,
+  SMI                       = 1,
+  DOUBLE                    = 2,
+  ANY                       = 3
+};
+
+
+inline bool IsMoreGeneralStorageType(StorageType first, StorageType second) {
+  ASSERT(second != ANY);
+  if (first == ANY) return false;
+  if (second == TAGGED) return false;
+  if (first == DOUBLE) return second == SMI;
+  return first != SMI;
+}
+
+
 // PropertyDetails captures type and attributes for a property.
 // They are used both in property dictionaries and instance descriptors.
 class PropertyDetails BASE_EMBEDDED {
  public:
   PropertyDetails(PropertyAttributes attributes,
                   PropertyType type,
                   int index = 0) {
     value_ = TypeField::encode(type)
+        | StorageTypeField::encode(TAGGED)
         | AttributesField::encode(attributes)
         | DictionaryStorageField::encode(index);
 
     ASSERT(type == this->type());
     ASSERT(attributes == this->attributes());
     ASSERT(index == this->dictionary_index());
   }
 
   int pointer() { return DescriptorPointer::decode(value_); }
 
   PropertyDetails set_pointer(int i) { return PropertyDetails(value_, i); }
 
+  PropertyDetails set_storage_type(StorageType storage) {
+    return PropertyDetails(value_, storage);
+  }
+
   // Conversion for storing details as Object*.
   explicit inline PropertyDetails(Smi* smi);
   inline Smi* AsSmi();
 
   PropertyType type() { return TypeField::decode(value_); }
 
   PropertyAttributes attributes() const {
     return AttributesField::decode(value_);
   }
 
   int dictionary_index() {
     return DictionaryStorageField::decode(value_);
   }
 
   int descriptor_index() {
     return DescriptorStorageField::decode(value_);
   }
 
+  StorageType storage_type() {
+    return StorageTypeField::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> {};
   class DictionaryStorageField:   public BitField<uint32_t,           7, 24> {};
   class DescriptorStorageField:   public BitField<uint32_t,           7, 11> {};
   class DescriptorPointer:        public BitField<uint32_t,          18, 11> {};
+  class StorageTypeField:         public BitField<StorageType,       29,  2> {};
 
   static const int kInitialIndex = 1;
 
  private:
   PropertyDetails(int value, int pointer) {
-      value_ = DescriptorPointer::update(value, pointer);
+    value_ = DescriptorPointer::update(value, pointer);
+  }
+  PropertyDetails(int value, StorageType storage) {
+    value_ = StorageTypeField::update(value, storage);
   }
 
   uint32_t value_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_