Cache maps for slow case objects.

src/objects.h

 // Copyright 2006-2009 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 613 matching lines @@
   inline bool IsJSValue();
   inline bool IsStringWrapper();
   inline bool IsProxy();
   inline bool IsBoolean();
   inline bool IsJSArray();
   inline bool IsJSRegExp();
   inline bool IsHashTable();
   inline bool IsDictionary();
   inline bool IsSymbolTable();
   inline bool IsJSFunctionResultCache();
+  inline bool IsNormalizedMapCache();
   inline bool IsCompilationCacheTable();
   inline bool IsCodeCacheHashTable();
   inline bool IsMapCache();
   inline bool IsPrimitive();
   inline bool IsGlobalObject();
   inline bool IsJSGlobalObject();
   inline bool IsJSBuiltinsObject();
   inline bool IsJSGlobalProxy();
   inline bool IsUndetectableObject();
   inline bool IsAccessCheckNeeded();
@@ skipping 1736 matching lines @@
 
   // Casting
   static inline JSFunctionResultCache* cast(Object* obj);
 
 #ifdef DEBUG
   void JSFunctionResultCacheVerify();
 #endif
 };
 
 
+// The cache for maps used by normalized (dictionary mode) objects.
+// Such maps do not have property descriptors, so a typical program
+// needs very limited number of distinct normalized maps.
+class NormalizedMapCache: public FixedArray {
+ public:
+  static const int kEntries = 256;
+
+  Object* Get(Map* fast, PropertyNormalizationMode mode);
+
+  void Clear();
+
+  // Casting
+  static inline NormalizedMapCache* cast(Object* obj);
+
+#ifdef DEBUG
+  void NormalizedMapCacheVerify();
+#endif
+
+ private:
+  static int Hash(Map* fast);
+
+  static bool CheckHit(Map* slow, Map* fast, PropertyNormalizationMode mode);
+};
+
+
 // ByteArray represents fixed sized byte arrays.  Used by the outside world,
 // such as PCRE, and also by the memory allocator and garbage collector to
 // fill in free blocks in the heap.
 class ByteArray: public HeapObject {
  public:
   // [length]: length of the array.
   inline int length();
   inline void set_length(int value);
 
   // Setter and getter.
@@ skipping 623 matching lines @@
   DECL_ACCESSORS(constructor, Object)
 
   // [instance descriptors]: describes the object.
   DECL_ACCESSORS(instance_descriptors, DescriptorArray)
 
   // [stub cache]: contains stubs compiled for this map.
   DECL_ACCESSORS(code_cache, Object)
 
   Object* CopyDropDescriptors();
 
+  Object* CopyNormalized(PropertyNormalizationMode mode);
+
   // Returns a copy of the map, with all transitions dropped from the
   // instance descriptors.
   Object* CopyDropTransitions();
 
   // Returns this map if it has the fast elements bit set, otherwise
   // returns a copy of the map, with all transitions dropped from the
   // descriptors and the fast elements bit set.
   inline Object* GetFastElementsMap();
 
   // Returns this map if it has the fast elements bit cleared,
@@ skipping 43 matching lines @@
   // Also, restore the original prototype on the targets of these
   // transitions, so that we do not process this map again while
   // following back pointers.
   void ClearNonLiveTransitions(Object* real_prototype);
 
   // Dispatched behavior.
   void MapIterateBody(ObjectVisitor* v);
 #ifdef DEBUG
   void MapPrint();
   void MapVerify();
+  void NormalizedMapVerify();
 #endif
 
   inline Scavenger scavenger();
   inline void set_scavenger(Scavenger callback);
 
   inline void Scavenge(HeapObject** slot, HeapObject* obj) {
     scavenger()(this, slot, obj);
   }
 
   static const int kMaxPreAllocatedPropertyFields = 255;
@@ skipping 18 matching lines @@
 
   // Byte offsets within kInstanceSizesOffset.
   static const int kInstanceSizeOffset = kInstanceSizesOffset + 0;
   static const int kInObjectPropertiesByte = 1;
   static const int kInObjectPropertiesOffset =
       kInstanceSizesOffset + kInObjectPropertiesByte;
   static const int kPreAllocatedPropertyFieldsByte = 2;
   static const int kPreAllocatedPropertyFieldsOffset =
       kInstanceSizesOffset + kPreAllocatedPropertyFieldsByte;
   // The byte at position 3 is not in use at the moment.
+  static const int kUnusedByte = 3;
+  static const int kUnusedOffset = kInstanceSizesOffset + kUnusedByte;
 
   // Byte offsets within kInstanceAttributesOffset attributes.
   static const int kInstanceTypeOffset = kInstanceAttributesOffset + 0;
   static const int kUnusedPropertyFieldsOffset = kInstanceAttributesOffset + 1;
   static const int kBitFieldOffset = kInstanceAttributesOffset + 2;
   static const int kBitField2Offset = kInstanceAttributesOffset + 3;
 
   STATIC_CHECK(kInstanceTypeOffset == Internals::kMapInstanceTypeOffset);
 
   // Bit positions for bit field.
@@ skipping 2220 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_