Make objects embedded in optimized code weak.

src/objects.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 1036 matching lines @@
   V(MapCache)                                  \
   V(Primitive)                                 \
   V(GlobalObject)                              \
   V(JSGlobalObject)                            \
   V(JSBuiltinsObject)                          \
   V(JSGlobalProxy)                             \
   V(UndetectableObject)                        \
   V(AccessCheckNeeded)                         \
   V(Cell)                                      \
   V(PropertyCell)                              \
-  V(ObjectHashTable)
+  V(ObjectHashTable)                           \
+  V(WeakHashTable)
 
 
 #define ERROR_MESSAGES_LIST(V) \
   V(kNoReason, "no reason")                                                   \
                                                                               \
   V(k32BitValueInRegisterIsNotZeroExtended,                                   \
     "32 bit value in register is not zero-extended")                          \
   V(kAlignmentMarkerExpected, "alignment marker expected")                    \
   V(kAllocationIsNotDoubleAligned, "Allocation is not double aligned")        \
   V(kAPICallReturnedInvalidObject, "API call returned invalid object")        \
@@ skipping 1837 matching lines @@
   inline void set_the_hole(int index);
 
   inline Object** GetFirstElementAddress();
   inline bool ContainsOnlySmisOrHoles();
 
   // Gives access to raw memory which stores the array's data.
   inline Object** data_start();
 
   // Copy operations.
   MUST_USE_RESULT inline MaybeObject* Copy();
-  MUST_USE_RESULT MaybeObject* CopySize(int new_length);
+  MUST_USE_RESULT MaybeObject* CopySize(int new_length,
+                                        PretenureFlag pretenure = NOT_TENURED);
 
   // Add the elements of a JSArray to this FixedArray.
   MUST_USE_RESULT MaybeObject* AddKeysFromJSArray(JSArray* array);
 
   // Compute the union of this and other.
   MUST_USE_RESULT MaybeObject* UnionOfKeys(FixedArray* other);
 
   // Copy a sub array from the receiver to dest.
   void CopyTo(int pos, FixedArray* dest, int dest_pos, int len);
 
@@ skipping 603 matching lines @@
 
   void Swap(uint32_t entry1, uint32_t entry2, WriteBarrierMode mode);
 
   // Rehashes this hash-table into the new table.
   MUST_USE_RESULT MaybeObject* Rehash(HashTable* new_table, Key key);
 
   // Attempt to shrink hash table after removal of key.
   MUST_USE_RESULT MaybeObject* Shrink(Key key);
 
   // Ensure enough space for n additional elements.
-  MUST_USE_RESULT MaybeObject* EnsureCapacity(int n, Key key);
+  MUST_USE_RESULT MaybeObject* EnsureCapacity(
+      int n,
+      Key key,
+      PretenureFlag pretenure = NOT_TENURED);
 };
 
 
 // HashTableKey is an abstract superclass for virtual key behavior.
 class HashTableKey {
  public:
   // Returns whether the other object matches this key.
   virtual bool IsMatch(Object* other) = 0;
   // Returns the hash value for this key.
   virtual uint32_t Hash() = 0;
@@ skipping 418 matching lines @@
   void AddEntry(int entry, Object* key, Object* value);
   void RemoveEntry(int entry);
 
   // Returns the index to the value of an entry.
   static inline int EntryToValueIndex(int entry) {
     return EntryToIndex(entry) + 1;
   }
 };
 
 
+template <int entrysize>
+class WeakHashTableShape : public BaseShape<Object*> {
+ public:
+  static inline bool IsMatch(Object* key, Object* other);
+  static inline uint32_t Hash(Object* key);
+  static inline uint32_t HashForObject(Object* key, Object* object);
+  MUST_USE_RESULT static inline MaybeObject* AsObject(Heap* heap,
+                                                      Object* key);
+  static const int kPrefixSize = 0;
+  static const int kEntrySize = entrysize;
+};
+
+
+// WeakHashTable maps keys that are arbitrary objects to object values.
+// It is used for the global weak hash table that maps objects
+// embedded in optimized code to dependent code lists.
+class WeakHashTable: public HashTable<WeakHashTableShape<2>, Object*> {
+ public:
+  static inline WeakHashTable* cast(Object* obj) {
+    ASSERT(obj->IsHashTable());
+    return reinterpret_cast<WeakHashTable*>(obj);
+  }
+
+  // Looks up the value associated with the given key. The hole value is
+  // returned in case the key is not present.
+  Object* Lookup(Object* key);
+
+  // Adds (or overwrites) the value associated with the given key. Mapping a
+  // key to the hole value causes removal of the whole entry.
+  MUST_USE_RESULT MaybeObject* Put(Object* key, Object* value);
+
+ private:
+  friend class MarkCompactCollector;
+
+  void AddEntry(int entry, Object* key, Object* value);
+
+  // Returns the index to the value of an entry.
+  static inline int EntryToValueIndex(int entry) {
+    return EntryToIndex(entry) + 1;
+  }
+};
+
+
 // JSFunctionResultCache caches results of some JSFunction invocation.
 // It is a fixed array with fixed structure:
 //   [0]: factory function
 //   [1]: finger index
 //   [2]: current cache size
 //   [3]: dummy field.
 // The rest of array are key/value pairs.
 class JSFunctionResultCache: public FixedArray {
  public:
   static const int kFactoryIndex = 0;
@@ skipping 1162 matching lines @@
   static void MakeCodeAgeSequenceYoung(byte* sequence);
   void MakeOlder(MarkingParity);
   static bool IsYoungSequence(byte* sequence);
   bool IsOld();
   int GetAge();
 
   void PrintDeoptLocation(int bailout_id);
   bool CanDeoptAt(Address pc);
 
 #ifdef VERIFY_HEAP
-  void VerifyEmbeddedMapsDependency();
+  void VerifyEmbeddedObjectsDependency();
 #endif
 
+  static bool IsWeakEmbeddedObject(Kind kind, Object* object);
+
   // Max loop nesting marker used to postpose OSR. We don't take loop
   // nesting that is deeper than 5 levels into account.
   static const int kMaxLoopNestingMarker = 6;
 
   // Layout description.
   static const int kInstructionSizeOffset = HeapObject::kHeaderSize;
   static const int kRelocationInfoOffset = kInstructionSizeOffset + kIntSize;
   static const int kHandlerTableOffset = kRelocationInfoOffset + kPointerSize;
   static const int kDeoptimizationDataOffset =
       kHandlerTableOffset + kPointerSize;
@@ skipping 5061 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_