prototype-info.h

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// 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"
#include "torque-generated/bit-fields.h"
 
// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"
 
namespace v8 {
namespace internal {
 
#include "torque-generated/src/objects/prototype-info-tq.inc"
 
// Container for metadata stored on each prototype map.
class PrototypeInfo
    : public TorqueGeneratedPrototypeInfo<PrototypeInfo, Struct> {
 public:
  static const int UNREGISTERED = -1;
 
  // For caching derived maps for Object.create, Reflect.construct and proxies.
  DECL_GETTER(derived_maps, Tagged<HeapObject>)
  DECL_RELEASE_ACQUIRE_ACCESSORS(derived_maps, Tagged<HeapObject>)
 
  static inline void SetObjectCreateMap(DirectHandle<PrototypeInfo> info,
                                        DirectHandle<Map> map,
                                        Isolate* isolate);
  inline Tagged<MaybeObject> ObjectCreateMap(AcquireLoadTag);
  inline Tagged<MaybeObject> ObjectCreateMap();
 
  static inline void AddDerivedMap(DirectHandle<PrototypeInfo> info,
                                   DirectHandle<Map> to, Isolate* isolate);
  inline Tagged<MaybeObject> GetDerivedMap(DirectHandle<Map> from);
 
  static inline bool IsPrototypeInfoFast(Tagged<Object> object);
 
  DECL_BOOLEAN_ACCESSORS(should_be_fast_map)
 
  // Dispatched behavior.
  DECL_PRINTER(PrototypeInfo)
  DECL_VERIFIER(PrototypeInfo)
 
  // Bit field usage.
  DEFINE_TORQUE_GENERATED_PROTOTYPE_INFO_FLAGS()
 
  class BodyDescriptor;
 
  TQ_OBJECT_CONSTRUCTORS(PrototypeInfo)
};
 
// 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,
                                   DirectHandle<Map> value,
                                   int* assigned_index);
 
  static inline void MarkSlotEmpty(Tagged<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 (*)(Tagged<HeapObject> object, int from_index,
                                      int to_index);
  static Tagged<WeakArrayList> Compact(
      DirectHandle<WeakArrayList> array, Heap* heap,
      CompactionCallback callback,
      AllocationType allocation = AllocationType::kYoung);
 
#ifdef VERIFY_HEAP
  static void Verify(Tagged<WeakArrayList> array);
#endif  // VERIFY_HEAP
 
  static const int kEmptySlotIndex = 0;
  static const int kFirstIndex = 1;
 
  static const int kNoEmptySlotsMarker = 0;
 
 private:
  static inline Tagged<Smi> empty_slot_index(Tagged<WeakArrayList> array);
  static inline void set_empty_slot_index(Tagged<WeakArrayList> array,
                                          int index);
 
  static void ScanForEmptySlots(Tagged<WeakArrayList> array);
 
  DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeUsers);
};
 
}  // namespace internal
}  // namespace v8
 
#include "src/objects/object-macros-undef.h"
 
#endif  // V8_OBJECTS_PROTOTYPE_INFO_H_