// Copyright 2018 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_PROTOTYPE_INFO_H_ #define V8_OBJECTS_PROTOTYPE_INFO_H_ #include "src/objects/fixed-array.h" #include "src/objects/objects.h" #include "src/objects/struct.h" // Has to be the last include (doesn't have include guards): #include "src/objects/object-macros.h" namespace v8 { namespace internal { // Container for metadata stored on each prototype map. class PrototypeInfo : public Struct { public: static const int UNREGISTERED = -1; // [module_namespace]: A backpointer to JSModuleNamespace from its // PrototypeInfo (or undefined). This field is only used for JSModuleNamespace // maps. TODO(jkummerow): Figure out if there's a way to store the namespace // pointer elsewhere to save memory. DECL_ACCESSORS(module_namespace, Object) // [prototype_users]: WeakArrayList containing weak references to maps using // this prototype, or Smi(0) if uninitialized. DECL_ACCESSORS(prototype_users, Object) DECL_ACCESSORS(prototype_chain_enum_cache, Object) // [object_create_map]: A field caching the map for Object.create(prototype). static inline void SetObjectCreateMap(Handle<PrototypeInfo> info, Handle<Map> map); inline Map ObjectCreateMap(); inline bool HasObjectCreateMap(); // [registry_slot]: Slot in prototype's user registry where this user // is stored. Returns UNREGISTERED if this prototype has not been registered. inline int registry_slot() const; inline void set_registry_slot(int slot); // [bit_field] inline int bit_field() const; inline void set_bit_field(int bit_field); DECL_BOOLEAN_ACCESSORS(should_be_fast_map) DECL_CAST(PrototypeInfo) // Dispatched behavior. DECL_PRINTER(PrototypeInfo) DECL_VERIFIER(PrototypeInfo) DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, TORQUE_GENERATED_PROTOTYPE_INFO_FIELDS) // Bit field usage. static const int kShouldBeFastBit = 0; class BodyDescriptor; private: DECL_ACCESSORS(object_create_map, MaybeObject) OBJECT_CONSTRUCTORS(PrototypeInfo, Struct); }; // A growing array with an additional API for marking slots "empty". When adding // new elements, we reuse the empty slots instead of growing the array. class V8_EXPORT_PRIVATE PrototypeUsers : public WeakArrayList { public: static Handle<WeakArrayList> Add(Isolate* isolate, Handle<WeakArrayList> array, Handle<Map> value, int* assigned_index); static inline void MarkSlotEmpty(WeakArrayList array, int index); // The callback is called when a weak pointer to HeapObject "object" is moved // from index "from_index" to index "to_index" during compaction. The callback // must not cause GC. using CompactionCallback = void (*)(HeapObject object, int from_index, int to_index); static WeakArrayList Compact( Handle<WeakArrayList> array, Heap* heap, CompactionCallback callback, AllocationType allocation = AllocationType::kYoung); #ifdef VERIFY_HEAP static void Verify(WeakArrayList array); #endif // VERIFY_HEAP static const int kEmptySlotIndex = 0; static const int kFirstIndex = 1; static const int kNoEmptySlotsMarker = 0; private: static inline Smi empty_slot_index(WeakArrayList array); static inline void set_empty_slot_index(WeakArrayList array, int index); static void ScanForEmptySlots(WeakArrayList array); DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeUsers); }; } // namespace internal } // namespace v8 #include "src/objects/object-macros-undef.h" #endif // V8_OBJECTS_PROTOTYPE_INFO_H_