1 // Copyright 2018 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_OBJECTS_PROTOTYPE_INFO_H_ 6 #define V8_OBJECTS_PROTOTYPE_INFO_H_ 7 8 #include "src/objects.h" 9 #include "src/objects/fixed-array.h" 10 11 // Has to be the last include (doesn't have include guards): 12 #include "src/objects/object-macros.h" 13 14 namespace v8 { 15 namespace internal { 16 17 // Container for metadata stored on each prototype map. 18 class PrototypeInfo : public Struct { 19 public: 20 static const int UNREGISTERED = -1; 21 22 // [module_namespace]: A backpointer to JSModuleNamespace from its 23 // PrototypeInfo (or undefined). This field is only used for JSModuleNamespace 24 // maps. TODO(jkummerow): Figure out if there's a way to store the namespace 25 // pointer elsewhere to save memory. 26 DECL_ACCESSORS(module_namespace, Object) 27 28 // [prototype_users]: WeakArrayList containing weak references to maps using 29 // this prototype, or Smi(0) if uninitialized. 30 DECL_ACCESSORS(prototype_users, Object) 31 32 // [object_create_map]: A field caching the map for Object.create(prototype). 33 static inline void SetObjectCreateMap(Handle<PrototypeInfo> info, 34 Handle<Map> map); 35 inline Map* ObjectCreateMap(); 36 inline bool HasObjectCreateMap(); 37 38 // [registry_slot]: Slot in prototype's user registry where this user 39 // is stored. Returns UNREGISTERED if this prototype has not been registered. 40 inline int registry_slot() const; 41 inline void set_registry_slot(int slot); 42 43 // [bit_field] 44 inline int bit_field() const; 45 inline void set_bit_field(int bit_field); 46 47 DECL_BOOLEAN_ACCESSORS(should_be_fast_map) 48 49 DECL_CAST(PrototypeInfo) 50 51 // Dispatched behavior. 52 DECL_PRINTER(PrototypeInfo) 53 DECL_VERIFIER(PrototypeInfo) 54 55 static const int kJSModuleNamespaceOffset = HeapObject::kHeaderSize; 56 static const int kPrototypeUsersOffset = 57 kJSModuleNamespaceOffset + kPointerSize; 58 static const int kRegistrySlotOffset = kPrototypeUsersOffset + kPointerSize; 59 static const int kValidityCellOffset = kRegistrySlotOffset + kPointerSize; 60 static const int kObjectCreateMapOffset = kValidityCellOffset + kPointerSize; 61 static const int kBitFieldOffset = kObjectCreateMapOffset + kPointerSize; 62 static const int kSize = kBitFieldOffset + kPointerSize; 63 64 // Bit field usage. 65 static const int kShouldBeFastBit = 0; 66 67 class BodyDescriptor; 68 69 private: 70 DECL_ACCESSORS(object_create_map, MaybeObject) 71 72 DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeInfo); 73 }; 74 75 // A growing array with an additional API for marking slots "empty". When adding 76 // new elements, we reuse the empty slots instead of growing the array. 77 class PrototypeUsers : public WeakArrayList { 78 public: 79 static Handle<WeakArrayList> Add(Isolate* isolate, 80 Handle<WeakArrayList> array, 81 Handle<Map> value, int* assigned_index); 82 83 static inline void MarkSlotEmpty(WeakArrayList* array, int index); 84 85 // The callback is called when a weak pointer to HeapObject "object" is moved 86 // from index "from_index" to index "to_index" during compaction. The callback 87 // must not cause GC. 88 typedef void (*CompactionCallback)(HeapObject* object, int from_index, 89 int to_index); 90 static WeakArrayList* Compact(Handle<WeakArrayList> array, Heap* heap, 91 CompactionCallback callback, 92 PretenureFlag pretenure = NOT_TENURED); 93 94 #ifdef VERIFY_HEAP 95 static void Verify(WeakArrayList* array); 96 #endif // VERIFY_HEAP 97 98 static const int kEmptySlotIndex = 0; 99 static const int kFirstIndex = 1; 100 101 static const int kNoEmptySlotsMarker = 0; 102 103 private: 104 static inline Smi* empty_slot_index(WeakArrayList* array); 105 static inline void set_empty_slot_index(WeakArrayList* array, int index); 106 107 static void IsSlotEmpty(WeakArrayList* array, int index); 108 109 DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeUsers); 110 }; 111 112 } // namespace internal 113 } // namespace v8 114 115 #include "src/objects/object-macros-undef.h" 116 117 #endif // V8_OBJECTS_PROTOTYPE_INFO_H_ 118