| // Copyright 2017 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_MAP_H_ |
| #define V8_OBJECTS_MAP_H_ |
| |
| #include "src/globals.h" |
| #include "src/objects.h" |
| #include "src/objects/code.h" |
| #include "src/objects/heap-object.h" |
| |
| // Has to be the last include (doesn't have include guards): |
| #include "src/objects/object-macros.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| enum InstanceType : uint16_t; |
| |
| #define VISITOR_ID_LIST(V) \ |
| V(AllocationSite) \ |
| V(BigInt) \ |
| V(ByteArray) \ |
| V(BytecodeArray) \ |
| V(Cell) \ |
| V(Code) \ |
| V(CodeDataContainer) \ |
| V(ConsString) \ |
| V(Context) \ |
| V(DataHandler) \ |
| V(DataObject) \ |
| V(DescriptorArray) \ |
| V(EmbedderDataArray) \ |
| V(EphemeronHashTable) \ |
| V(FeedbackCell) \ |
| V(FeedbackVector) \ |
| V(FixedArray) \ |
| V(FixedDoubleArray) \ |
| V(FixedFloat64Array) \ |
| V(FixedTypedArrayBase) \ |
| V(FreeSpace) \ |
| V(JSApiObject) \ |
| V(JSArrayBuffer) \ |
| V(JSDataView) \ |
| V(JSObject) \ |
| V(JSObjectFast) \ |
| V(JSTypedArray) \ |
| V(JSWeakCell) \ |
| V(JSWeakRef) \ |
| V(JSWeakCollection) \ |
| V(Map) \ |
| V(NativeContext) \ |
| V(Oddball) \ |
| V(PreParsedScopeData) \ |
| V(PropertyArray) \ |
| V(PropertyCell) \ |
| V(PrototypeInfo) \ |
| V(SeqOneByteString) \ |
| V(SeqTwoByteString) \ |
| V(SharedFunctionInfo) \ |
| V(ShortcutCandidate) \ |
| V(SlicedString) \ |
| V(SmallOrderedHashMap) \ |
| V(SmallOrderedHashSet) \ |
| V(SmallOrderedNameDictionary) \ |
| V(Struct) \ |
| V(Symbol) \ |
| V(ThinString) \ |
| V(TransitionArray) \ |
| V(UncompiledDataWithoutPreParsedScope) \ |
| V(UncompiledDataWithPreParsedScope) \ |
| V(WasmInstanceObject) \ |
| V(WeakArray) |
| |
| // For data objects, JS objects and structs along with generic visitor which |
| // can visit object of any size we provide visitors specialized by |
| // object size in words. |
| // Ids of specialized visitors are declared in a linear order (without |
| // holes) starting from the id of visitor specialized for 2 words objects |
| // (base visitor id) and ending with the id of generic visitor. |
| // Method GetVisitorIdForSize depends on this ordering to calculate visitor |
| // id of specialized visitor from given instance size, base visitor id and |
| // generic visitor's id. |
| enum VisitorId { |
| #define VISITOR_ID_ENUM_DECL(id) kVisit##id, |
| VISITOR_ID_LIST(VISITOR_ID_ENUM_DECL) |
| #undef VISITOR_ID_ENUM_DECL |
| kVisitorIdCount |
| }; |
| |
| typedef std::vector<Handle<Map>> MapHandles; |
| |
| // All heap objects have a Map that describes their structure. |
| // A Map contains information about: |
| // - Size information about the object |
| // - How to iterate over an object (for garbage collection) |
| // |
| // Map layout: |
| // +---------------+---------------------------------------------+ |
| // | _ Type _ | _ Description _ | |
| // +---------------+---------------------------------------------+ |
| // | TaggedPointer | map - Always a pointer to the MetaMap root | |
| // +---------------+---------------------------------------------+ |
| // | Int | The first int field | |
| // `---+----------+---------------------------------------------+ |
| // | Byte | [instance_size] | |
| // +----------+---------------------------------------------+ |
| // | Byte | If Map for a primitive type: | |
| // | | native context index for constructor fn | |
| // | | If Map for an Object type: | |
| // | | inobject properties start offset in words | |
| // +----------+---------------------------------------------+ |
| // | Byte | [used_or_unused_instance_size_in_words] | |
| // | | For JSObject in fast mode this byte encodes | |
| // | | the size of the object that includes only | |
| // | | the used property fields or the slack size | |
| // | | in properties backing store. | |
| // +----------+---------------------------------------------+ |
| // | Byte | [visitor_id] | |
| // +----+----------+---------------------------------------------+ |
| // | Int | The second int field | |
| // `---+----------+---------------------------------------------+ |
| // | Short | [instance_type] | |
| // +----------+---------------------------------------------+ |
| // | Byte | [bit_field] | |
| // | | - has_non_instance_prototype (bit 0) | |
| // | | - is_callable (bit 1) | |
| // | | - has_named_interceptor (bit 2) | |
| // | | - has_indexed_interceptor (bit 3) | |
| // | | - is_undetectable (bit 4) | |
| // | | - is_access_check_needed (bit 5) | |
| // | | - is_constructor (bit 6) | |
| // | | - has_prototype_slot (bit 7) | |
| // +----------+---------------------------------------------+ |
| // | Byte | [bit_field2] | |
| // | | - is_extensible (bit 0) | |
| // | | - is_prototype_map (bit 1) | |
| // | | - is_in_retained_map_list (bit 2) | |
| // | | - elements_kind (bits 3..7) | |
| // +----+----------+---------------------------------------------+ |
| // | Int | [bit_field3] | |
| // | | - enum_length (bit 0..9) | |
| // | | - number_of_own_descriptors (bit 10..19) | |
| // | | - is_dictionary_map (bit 20) | |
| // | | - owns_descriptors (bit 21) | |
| // | | - has_hidden_prototype (bit 22) | |
| // | | - is_deprecated (bit 23) | |
| // | | - is_unstable (bit 24) | |
| // | | - is_migration_target (bit 25) | |
| // | | - is_immutable_proto (bit 26) | |
| // | | - new_target_is_base (bit 27) | |
| // | | - may_have_interesting_symbols (bit 28) | |
| // | | - construction_counter (bit 29..31) | |
| // | | | |
| // +*************************************************************+ |
| // | Int | On systems with 64bit pointer types, there | |
| // | | is an unused 32bits after bit_field3 | |
| // +*************************************************************+ |
| // | TaggedPointer | [prototype] | |
| // +---------------+---------------------------------------------+ |
| // | TaggedPointer | [constructor_or_backpointer] | |
| // +---------------+---------------------------------------------+ |
| // | TaggedPointer | If Map is a prototype map: | |
| // | | [prototype_info] | |
| // | | Else: | |
| // | | [raw_transitions] | |
| // +---------------+---------------------------------------------+ |
| // | TaggedPointer | [instance_descriptors] | |
| // +*************************************************************+ |
| // ! TaggedPointer ! [layout_descriptors] ! |
| // ! ! Field is only present if compile-time flag ! |
| // ! ! FLAG_unbox_double_fields is enabled ! |
| // ! ! (basically on 64 bit architectures) ! |
| // +*************************************************************+ |
| // | TaggedPointer | [dependent_code] | |
| // +---------------+---------------------------------------------+ |
| |
| class Map : public HeapObject { |
| public: |
| // Instance size. |
| // Size in bytes or kVariableSizeSentinel if instances do not have |
| // a fixed size. |
| DECL_INT_ACCESSORS(instance_size) |
| // Size in words or kVariableSizeSentinel if instances do not have |
| // a fixed size. |
| DECL_INT_ACCESSORS(instance_size_in_words) |
| |
| // [inobject_properties_start_or_constructor_function_index]: |
| // Provides access to the inobject properties start offset in words in case of |
| // JSObject maps, or the constructor function index in case of primitive maps. |
| DECL_INT_ACCESSORS(inobject_properties_start_or_constructor_function_index) |
| |
| // Get/set the in-object property area start offset in words in the object. |
| inline int GetInObjectPropertiesStartInWords() const; |
| inline void SetInObjectPropertiesStartInWords(int value); |
| // Count of properties allocated in the object (JSObject only). |
| inline int GetInObjectProperties() const; |
| // Index of the constructor function in the native context (primitives only), |
| // or the special sentinel value to indicate that there is no object wrapper |
| // for the primitive (i.e. in case of null or undefined). |
| static const int kNoConstructorFunctionIndex = 0; |
| inline int GetConstructorFunctionIndex() const; |
| inline void SetConstructorFunctionIndex(int value); |
| static MaybeHandle<JSFunction> GetConstructorFunction( |
| Handle<Map> map, Handle<Context> native_context); |
| |
| // Retrieve interceptors. |
| inline InterceptorInfo GetNamedInterceptor(); |
| inline InterceptorInfo GetIndexedInterceptor(); |
| |
| // Instance type. |
| DECL_PRIMITIVE_ACCESSORS(instance_type, InstanceType) |
| |
| // Returns the size of the used in-object area including object header |
| // (only used for JSObject in fast mode, for the other kinds of objects it |
| // is equal to the instance size). |
| inline int UsedInstanceSize() const; |
| |
| // Tells how many unused property fields (in-object or out-of object) are |
| // available in the instance (only used for JSObject in fast mode). |
| inline int UnusedPropertyFields() const; |
| // Tells how many unused in-object property words are present. |
| inline int UnusedInObjectProperties() const; |
| // Updates the counters tracking unused fields in the object. |
| inline void SetInObjectUnusedPropertyFields(int unused_property_fields); |
| // Updates the counters tracking unused fields in the property array. |
| inline void SetOutOfObjectUnusedPropertyFields(int unused_property_fields); |
| inline void CopyUnusedPropertyFields(Map map); |
| inline void CopyUnusedPropertyFieldsAdjustedForInstanceSize(Map map); |
| inline void AccountAddedPropertyField(); |
| inline void AccountAddedOutOfObjectPropertyField( |
| int unused_in_property_array); |
| |
| // |
| // Bit field. |
| // |
| DECL_PRIMITIVE_ACCESSORS(bit_field, byte) |
| |
| // Bit positions for |bit_field|. |
| #define MAP_BIT_FIELD_FIELDS(V, _) \ |
| V(HasNonInstancePrototypeBit, bool, 1, _) \ |
| V(IsCallableBit, bool, 1, _) \ |
| V(HasNamedInterceptorBit, bool, 1, _) \ |
| V(HasIndexedInterceptorBit, bool, 1, _) \ |
| V(IsUndetectableBit, bool, 1, _) \ |
| V(IsAccessCheckNeededBit, bool, 1, _) \ |
| V(IsConstructorBit, bool, 1, _) \ |
| V(HasPrototypeSlotBit, bool, 1, _) |
| |
| DEFINE_BIT_FIELDS(MAP_BIT_FIELD_FIELDS) |
| #undef MAP_BIT_FIELD_FIELDS |
| |
| // |
| // Bit field 2. |
| // |
| DECL_PRIMITIVE_ACCESSORS(bit_field2, byte) |
| |
| // Bit positions for |bit_field2|. |
| #define MAP_BIT_FIELD2_FIELDS(V, _) \ |
| V(IsExtensibleBit, bool, 1, _) \ |
| V(IsPrototypeMapBit, bool, 1, _) \ |
| V(IsInRetainedMapListBit, bool, 1, _) \ |
| V(ElementsKindBits, ElementsKind, 5, _) |
| |
| DEFINE_BIT_FIELDS(MAP_BIT_FIELD2_FIELDS) |
| #undef MAP_BIT_FIELD2_FIELDS |
| |
| // |
| // Bit field 3. |
| // |
| DECL_PRIMITIVE_ACCESSORS(bit_field3, uint32_t) |
| |
| // Bit positions for |bit_field3|. |
| #define MAP_BIT_FIELD3_FIELDS(V, _) \ |
| V(EnumLengthBits, int, kDescriptorIndexBitCount, _) \ |
| V(NumberOfOwnDescriptorsBits, int, kDescriptorIndexBitCount, _) \ |
| V(IsDictionaryMapBit, bool, 1, _) \ |
| V(OwnsDescriptorsBit, bool, 1, _) \ |
| V(HasHiddenPrototypeBit, bool, 1, _) \ |
| V(IsDeprecatedBit, bool, 1, _) \ |
| V(IsUnstableBit, bool, 1, _) \ |
| V(IsMigrationTargetBit, bool, 1, _) \ |
| V(IsImmutablePrototypeBit, bool, 1, _) \ |
| V(NewTargetIsBaseBit, bool, 1, _) \ |
| V(MayHaveInterestingSymbolsBit, bool, 1, _) \ |
| V(ConstructionCounterBits, int, 3, _) |
| |
| DEFINE_BIT_FIELDS(MAP_BIT_FIELD3_FIELDS) |
| #undef MAP_BIT_FIELD3_FIELDS |
| |
| STATIC_ASSERT(NumberOfOwnDescriptorsBits::kMax >= kMaxNumberOfDescriptors); |
| |
| static const int kSlackTrackingCounterStart = 7; |
| static const int kSlackTrackingCounterEnd = 1; |
| static const int kNoSlackTracking = 0; |
| STATIC_ASSERT(kSlackTrackingCounterStart <= ConstructionCounterBits::kMax); |
| |
| // Inobject slack tracking is the way to reclaim unused inobject space. |
| // |
| // The instance size is initially determined by adding some slack to |
| // expected_nof_properties (to allow for a few extra properties added |
| // after the constructor). There is no guarantee that the extra space |
| // will not be wasted. |
| // |
| // Here is the algorithm to reclaim the unused inobject space: |
| // - Detect the first constructor call for this JSFunction. |
| // When it happens enter the "in progress" state: initialize construction |
| // counter in the initial_map. |
| // - While the tracking is in progress initialize unused properties of a new |
| // object with one_pointer_filler_map instead of undefined_value (the "used" |
| // part is initialized with undefined_value as usual). This way they can |
| // be resized quickly and safely. |
| // - Once enough objects have been created compute the 'slack' |
| // (traverse the map transition tree starting from the |
| // initial_map and find the lowest value of unused_property_fields). |
| // - Traverse the transition tree again and decrease the instance size |
| // of every map. Existing objects will resize automatically (they are |
| // filled with one_pointer_filler_map). All further allocations will |
| // use the adjusted instance size. |
| // - SharedFunctionInfo's expected_nof_properties left unmodified since |
| // allocations made using different closures could actually create different |
| // kind of objects (see prototype inheritance pattern). |
| // |
| // Important: inobject slack tracking is not attempted during the snapshot |
| // creation. |
| |
| static const int kGenerousAllocationCount = |
| kSlackTrackingCounterStart - kSlackTrackingCounterEnd + 1; |
| |
| // Starts the tracking by initializing object constructions countdown counter. |
| void StartInobjectSlackTracking(); |
| |
| // True if the object constructions countdown counter is a range |
| // [kSlackTrackingCounterEnd, kSlackTrackingCounterStart]. |
| inline bool IsInobjectSlackTrackingInProgress() const; |
| |
| // Does the tracking step. |
| inline void InobjectSlackTrackingStep(Isolate* isolate); |
| |
| // Computes inobject slack for the transition tree starting at this initial |
| // map. |
| int ComputeMinObjectSlack(Isolate* isolate); |
| inline int InstanceSizeFromSlack(int slack) const; |
| |
| // Completes inobject slack tracking for the transition tree starting at this |
| // initial map. |
| void CompleteInobjectSlackTracking(Isolate* isolate); |
| |
| // Tells whether the object in the prototype property will be used |
| // for instances created from this function. If the prototype |
| // property is set to a value that is not a JSObject, the prototype |
| // property will not be used to create instances of the function. |
| // See ECMA-262, 13.2.2. |
| DECL_BOOLEAN_ACCESSORS(has_non_instance_prototype) |
| |
| // Tells whether the instance has a [[Construct]] internal method. |
| // This property is implemented according to ES6, section 7.2.4. |
| DECL_BOOLEAN_ACCESSORS(is_constructor) |
| |
| // Tells whether the instance with this map may have properties for |
| // interesting symbols on it. |
| // An "interesting symbol" is one for which Name::IsInterestingSymbol() |
| // returns true, i.e. a well-known symbol like @@toStringTag. |
| DECL_BOOLEAN_ACCESSORS(may_have_interesting_symbols) |
| |
| DECL_BOOLEAN_ACCESSORS(has_prototype_slot) |
| |
| // Tells whether the instance with this map has a hidden prototype. |
| DECL_BOOLEAN_ACCESSORS(has_hidden_prototype) |
| |
| // Records and queries whether the instance has a named interceptor. |
| DECL_BOOLEAN_ACCESSORS(has_named_interceptor) |
| |
| // Records and queries whether the instance has an indexed interceptor. |
| DECL_BOOLEAN_ACCESSORS(has_indexed_interceptor) |
| |
| // Tells whether the instance is undetectable. |
| // An undetectable object is a special class of JSObject: 'typeof' operator |
| // returns undefined, ToBoolean returns false. Otherwise it behaves like |
| // a normal JS object. It is useful for implementing undetectable |
| // document.all in Firefox & Safari. |
| // See https://bugzilla.mozilla.org/show_bug.cgi?id=248549. |
| DECL_BOOLEAN_ACCESSORS(is_undetectable) |
| |
| // Tells whether the instance has a [[Call]] internal method. |
| // This property is implemented according to ES6, section 7.2.3. |
| DECL_BOOLEAN_ACCESSORS(is_callable) |
| |
| DECL_BOOLEAN_ACCESSORS(new_target_is_base) |
| DECL_BOOLEAN_ACCESSORS(is_extensible) |
| DECL_BOOLEAN_ACCESSORS(is_prototype_map) |
| inline bool is_abandoned_prototype_map() const; |
| |
| // Whether the instance has been added to the retained map list by |
| // Heap::AddRetainedMap. |
| DECL_BOOLEAN_ACCESSORS(is_in_retained_map_list) |
| |
| DECL_PRIMITIVE_ACCESSORS(elements_kind, ElementsKind) |
| |
| // Tells whether the instance has fast elements that are only Smis. |
| inline bool has_fast_smi_elements() const; |
| |
| // Tells whether the instance has fast elements. |
| inline bool has_fast_object_elements() const; |
| inline bool has_fast_smi_or_object_elements() const; |
| inline bool has_fast_double_elements() const; |
| inline bool has_fast_elements() const; |
| inline bool has_sloppy_arguments_elements() const; |
| inline bool has_fast_sloppy_arguments_elements() const; |
| inline bool has_fast_string_wrapper_elements() const; |
| inline bool has_fixed_typed_array_elements() const; |
| inline bool has_dictionary_elements() const; |
| |
| // Returns true if the current map doesn't have DICTIONARY_ELEMENTS but if a |
| // map with DICTIONARY_ELEMENTS was found in the prototype chain. |
| bool DictionaryElementsInPrototypeChainOnly(Isolate* isolate); |
| |
| inline Map ElementsTransitionMap(); |
| |
| inline FixedArrayBase GetInitialElements() const; |
| |
| // [raw_transitions]: Provides access to the transitions storage field. |
| // Don't call set_raw_transitions() directly to overwrite transitions, use |
| // the TransitionArray::ReplaceTransitions() wrapper instead! |
| DECL_ACCESSORS2(raw_transitions, MaybeObject) |
| // [prototype_info]: Per-prototype metadata. Aliased with transitions |
| // (which prototype maps don't have). |
| DECL_ACCESSORS(prototype_info, Object) |
| // PrototypeInfo is created lazily using this helper (which installs it on |
| // the given prototype's map). |
| static Handle<PrototypeInfo> GetOrCreatePrototypeInfo( |
| Handle<JSObject> prototype, Isolate* isolate); |
| static Handle<PrototypeInfo> GetOrCreatePrototypeInfo( |
| Handle<Map> prototype_map, Isolate* isolate); |
| inline bool should_be_fast_prototype_map() const; |
| static void SetShouldBeFastPrototypeMap(Handle<Map> map, bool value, |
| Isolate* isolate); |
| |
| // [prototype chain validity cell]: Associated with a prototype object, |
| // stored in that object's map, indicates that prototype chains through this |
| // object are currently valid. The cell will be invalidated and replaced when |
| // the prototype chain changes. When there's nothing to guard (for example, |
| // when direct prototype is null or Proxy) this function returns Smi with |
| // |kPrototypeChainValid| sentinel value. |
| static Handle<Object> GetOrCreatePrototypeChainValidityCell(Handle<Map> map, |
| Isolate* isolate); |
| static const int kPrototypeChainValid = 0; |
| static const int kPrototypeChainInvalid = 1; |
| |
| static bool IsPrototypeChainInvalidated(Map map); |
| |
| // Return the map of the root of object's prototype chain. |
| Map GetPrototypeChainRootMap(Isolate* isolate) const; |
| |
| Map FindRootMap(Isolate* isolate) const; |
| Map FindFieldOwner(Isolate* isolate, int descriptor) const; |
| |
| inline int GetInObjectPropertyOffset(int index) const; |
| |
| class FieldCounts { |
| public: |
| FieldCounts(int mutable_count, int const_count) |
| : mutable_count_(mutable_count), const_count_(const_count) {} |
| |
| int GetTotal() const { return mutable_count() + const_count(); } |
| |
| int mutable_count() const { return mutable_count_; } |
| int const_count() const { return const_count_; } |
| |
| private: |
| int mutable_count_; |
| int const_count_; |
| }; |
| |
| FieldCounts GetFieldCounts() const; |
| int NumberOfFields() const; |
| |
| bool HasOutOfObjectProperties() const; |
| |
| // Returns true if transition to the given map requires special |
| // synchronization with the concurrent marker. |
| bool TransitionRequiresSynchronizationWithGC(Map target) const; |
| // Returns true if transition to the given map removes a tagged in-object |
| // field. |
| bool TransitionRemovesTaggedField(Map target) const; |
| // Returns true if transition to the given map replaces a tagged in-object |
| // field with an untagged in-object field. |
| bool TransitionChangesTaggedFieldToUntaggedField(Map target) const; |
| |
| // TODO(ishell): candidate with JSObject::MigrateToMap(). |
| bool InstancesNeedRewriting(Map target) const; |
| bool InstancesNeedRewriting(Map target, int target_number_of_fields, |
| int target_inobject, int target_unused, |
| int* old_number_of_fields) const; |
| V8_WARN_UNUSED_RESULT static Handle<FieldType> GeneralizeFieldType( |
| Representation rep1, Handle<FieldType> type1, Representation rep2, |
| Handle<FieldType> type2, Isolate* isolate); |
| static void GeneralizeField(Isolate* isolate, Handle<Map> map, |
| int modify_index, PropertyConstness new_constness, |
| Representation new_representation, |
| Handle<FieldType> new_field_type); |
| // Returns true if |descriptor|'th property is a field that may be generalized |
| // by just updating current map. |
| static inline bool IsInplaceGeneralizableField(PropertyConstness constness, |
| Representation representation, |
| FieldType field_type); |
| |
| // Generalizes constness, representation and field_type if objects with given |
| // instance type can have fast elements that can be transitioned by stubs or |
| // optimized code to more general elements kind. |
| // This generalization is necessary in order to ensure that elements kind |
| // transitions performed by stubs / optimized code don't silently transition |
| // PropertyConstness::kMutable fields back to VariableMode::kConst state or |
| // fields with HeapObject representation and "Any" type back to "Class" type. |
| static inline void GeneralizeIfCanHaveTransitionableFastElementsKind( |
| Isolate* isolate, InstanceType instance_type, |
| PropertyConstness* constness, Representation* representation, |
| Handle<FieldType>* field_type); |
| |
| static Handle<Map> ReconfigureProperty(Isolate* isolate, Handle<Map> map, |
| int modify_index, |
| PropertyKind new_kind, |
| PropertyAttributes new_attributes, |
| Representation new_representation, |
| Handle<FieldType> new_field_type); |
| |
| static Handle<Map> ReconfigureElementsKind(Isolate* isolate, Handle<Map> map, |
| ElementsKind new_elements_kind); |
| |
| static Handle<Map> PrepareForDataProperty(Isolate* isolate, |
| Handle<Map> old_map, |
| int descriptor_number, |
| PropertyConstness constness, |
| Handle<Object> value); |
| |
| static Handle<Map> Normalize(Isolate* isolate, Handle<Map> map, |
| PropertyNormalizationMode mode, |
| const char* reason); |
| |
| // Tells whether the map is used for JSObjects in dictionary mode (ie |
| // normalized objects, ie objects for which HasFastProperties returns false). |
| // A map can never be used for both dictionary mode and fast mode JSObjects. |
| // False by default and for HeapObjects that are not JSObjects. |
| DECL_BOOLEAN_ACCESSORS(is_dictionary_map) |
| |
| // Tells whether the instance needs security checks when accessing its |
| // properties. |
| DECL_BOOLEAN_ACCESSORS(is_access_check_needed) |
| |
| // [prototype]: implicit prototype object. |
| DECL_ACCESSORS(prototype, Object) |
| // TODO(jkummerow): make set_prototype private. |
| static void SetPrototype(Isolate* isolate, Handle<Map> map, |
| Handle<Object> prototype, |
| bool enable_prototype_setup_mode = true); |
| |
| // [constructor]: points back to the function or FunctionTemplateInfo |
| // responsible for this map. |
| // The field overlaps with the back pointer. All maps in a transition tree |
| // have the same constructor, so maps with back pointers can walk the |
| // back pointer chain until they find the map holding their constructor. |
| // Returns null_value if there's neither a constructor function nor a |
| // FunctionTemplateInfo available. |
| DECL_ACCESSORS(constructor_or_backpointer, Object) |
| inline Object* GetConstructor() const; |
| inline FunctionTemplateInfo GetFunctionTemplateInfo() const; |
| inline void SetConstructor(Object* constructor, |
| WriteBarrierMode mode = UPDATE_WRITE_BARRIER); |
| // [back pointer]: points back to the parent map from which a transition |
| // leads to this map. The field overlaps with the constructor (see above). |
| inline Object* GetBackPointer() const; |
| inline void SetBackPointer(Object* value, |
| WriteBarrierMode mode = UPDATE_WRITE_BARRIER); |
| |
| // [instance descriptors]: describes the object. |
| inline DescriptorArray instance_descriptors() const; |
| void SetInstanceDescriptors(Isolate* isolate, DescriptorArray descriptors, |
| int number_of_own_descriptors); |
| |
| // [layout descriptor]: describes the object layout. |
| DECL_ACCESSORS2(layout_descriptor, LayoutDescriptor) |
| // |layout descriptor| accessor which can be used from GC. |
| inline LayoutDescriptor layout_descriptor_gc_safe() const; |
| inline bool HasFastPointerLayout() const; |
| |
| // |layout descriptor| accessor that is safe to call even when |
| // FLAG_unbox_double_fields is disabled (in this case Map does not contain |
| // |layout_descriptor| field at all). |
| inline LayoutDescriptor GetLayoutDescriptor() const; |
| |
| inline void UpdateDescriptors(Isolate* isolate, DescriptorArray descriptors, |
| LayoutDescriptor layout_descriptor, |
| int number_of_own_descriptors); |
| inline void InitializeDescriptors(Isolate* isolate, |
| DescriptorArray descriptors, |
| LayoutDescriptor layout_descriptor); |
| |
| // [dependent code]: list of optimized codes that weakly embed this map. |
| DECL_ACCESSORS2(dependent_code, DependentCode) |
| |
| // [prototype_validity_cell]: Cell containing the validity bit for prototype |
| // chains or Smi(0) if uninitialized. |
| // The meaning of this validity cell is different for prototype maps and |
| // non-prototype maps. |
| // For prototype maps the validity bit "guards" modifications of prototype |
| // chains going through this object. When a prototype object changes, both its |
| // own validity cell and those of all "downstream" prototypes are invalidated; |
| // handlers for a given receiver embed the currently valid cell for that |
| // receiver's prototype during their creation and check it on execution. |
| // For non-prototype maps which are used as transitioning store handlers this |
| // field contains the validity cell which guards modifications of this map's |
| // prototype. |
| DECL_ACCESSORS(prototype_validity_cell, Object) |
| |
| // Returns true if prototype validity cell value represents "valid" prototype |
| // chain state. |
| inline bool IsPrototypeValidityCellValid() const; |
| |
| inline PropertyDetails GetLastDescriptorDetails() const; |
| |
| inline int LastAdded() const; |
| |
| inline int NumberOfOwnDescriptors() const; |
| inline void SetNumberOfOwnDescriptors(int number); |
| |
| inline Cell RetrieveDescriptorsPointer(); |
| |
| // Checks whether all properties are stored either in the map or on the object |
| // (inobject, properties, or elements backing store), requiring no special |
| // checks. |
| bool OnlyHasSimpleProperties() const; |
| inline int EnumLength() const; |
| inline void SetEnumLength(int length); |
| |
| DECL_BOOLEAN_ACCESSORS(owns_descriptors) |
| |
| inline void mark_unstable(); |
| inline bool is_stable() const; |
| |
| DECL_BOOLEAN_ACCESSORS(is_migration_target) |
| |
| DECL_BOOLEAN_ACCESSORS(is_immutable_proto) |
| |
| // This counter is used for in-object slack tracking. |
| // The in-object slack tracking is considered enabled when the counter is |
| // non zero. The counter only has a valid count for initial maps. For |
| // transitioned maps only kNoSlackTracking has a meaning, namely that inobject |
| // slack tracking already finished for the transition tree. Any other value |
| // indicates that either inobject slack tracking is still in progress, or that |
| // the map isn't part of the transition tree anymore. |
| DECL_INT_ACCESSORS(construction_counter) |
| |
| DECL_BOOLEAN_ACCESSORS(is_deprecated) |
| inline bool CanBeDeprecated() const; |
| // Returns a non-deprecated version of the input. If the input was not |
| // deprecated, it is directly returned. Otherwise, the non-deprecated version |
| // is found by re-transitioning from the root of the transition tree using the |
| // descriptor array of the map. Returns MaybeHandle<Map>() if no updated map |
| // is found. |
| static MaybeHandle<Map> TryUpdate(Isolate* isolate, |
| Handle<Map> map) V8_WARN_UNUSED_RESULT; |
| static Map TryUpdateSlow(Isolate* isolate, Map map) V8_WARN_UNUSED_RESULT; |
| |
| // Returns a non-deprecated version of the input. This method may deprecate |
| // existing maps along the way if encodings conflict. Not for use while |
| // gathering type feedback. Use TryUpdate in those cases instead. |
| static Handle<Map> Update(Isolate* isolate, Handle<Map> map); |
| |
| static inline Handle<Map> CopyInitialMap(Isolate* isolate, Handle<Map> map); |
| static Handle<Map> CopyInitialMap(Isolate* isolate, Handle<Map> map, |
| int instance_size, int in_object_properties, |
| int unused_property_fields); |
| static Handle<Map> CopyInitialMapNormalized( |
| Isolate* isolate, Handle<Map> map, |
| PropertyNormalizationMode mode = CLEAR_INOBJECT_PROPERTIES); |
| static Handle<Map> CopyDropDescriptors(Isolate* isolate, Handle<Map> map); |
| static Handle<Map> CopyInsertDescriptor(Isolate* isolate, Handle<Map> map, |
| Descriptor* descriptor, |
| TransitionFlag flag); |
| |
| static MaybeObjectHandle WrapFieldType(Isolate* isolate, |
| Handle<FieldType> type); |
| static FieldType UnwrapFieldType(MaybeObject wrapped_type); |
| |
| V8_WARN_UNUSED_RESULT static MaybeHandle<Map> CopyWithField( |
| Isolate* isolate, Handle<Map> map, Handle<Name> name, |
| Handle<FieldType> type, PropertyAttributes attributes, |
| PropertyConstness constness, Representation representation, |
| TransitionFlag flag); |
| |
| V8_WARN_UNUSED_RESULT static MaybeHandle<Map> CopyWithConstant( |
| Isolate* isolate, Handle<Map> map, Handle<Name> name, |
| Handle<Object> constant, PropertyAttributes attributes, |
| TransitionFlag flag); |
| |
| // Returns a new map with all transitions dropped from the given map and |
| // the ElementsKind set. |
| static Handle<Map> TransitionElementsTo(Isolate* isolate, Handle<Map> map, |
| ElementsKind to_kind); |
| |
| static Handle<Map> AsElementsKind(Isolate* isolate, Handle<Map> map, |
| ElementsKind kind); |
| |
| static Handle<Map> CopyAsElementsKind(Isolate* isolate, Handle<Map> map, |
| ElementsKind kind, TransitionFlag flag); |
| |
| static Handle<Map> AsLanguageMode(Isolate* isolate, Handle<Map> initial_map, |
| Handle<SharedFunctionInfo> shared_info); |
| |
| static Handle<Map> CopyForPreventExtensions(Isolate* isolate, Handle<Map> map, |
| PropertyAttributes attrs_to_add, |
| Handle<Symbol> transition_marker, |
| const char* reason); |
| |
| static Handle<Map> FixProxy(Handle<Map> map, InstanceType type, int size); |
| |
| // Maximal number of fast properties. Used to restrict the number of map |
| // transitions to avoid an explosion in the number of maps for objects used as |
| // dictionaries. |
| inline bool TooManyFastProperties(StoreOrigin store_origin) const; |
| static Handle<Map> TransitionToDataProperty(Isolate* isolate, Handle<Map> map, |
| Handle<Name> name, |
| Handle<Object> value, |
| PropertyAttributes attributes, |
| PropertyConstness constness, |
| StoreOrigin store_origin); |
| static Handle<Map> TransitionToAccessorProperty( |
| Isolate* isolate, Handle<Map> map, Handle<Name> name, int descriptor, |
| Handle<Object> getter, Handle<Object> setter, |
| PropertyAttributes attributes); |
| static Handle<Map> ReconfigureExistingProperty(Isolate* isolate, |
| Handle<Map> map, |
| int descriptor, |
| PropertyKind kind, |
| PropertyAttributes attributes); |
| |
| inline void AppendDescriptor(Isolate* isolate, Descriptor* desc); |
| |
| // Returns a copy of the map, prepared for inserting into the transition |
| // tree (if the |map| owns descriptors then the new one will share |
| // descriptors with |map|). |
| static Handle<Map> CopyForElementsTransition(Isolate* isolate, |
| Handle<Map> map); |
| |
| // Returns a copy of the map, with all transitions dropped from the |
| // instance descriptors. |
| static Handle<Map> Copy(Isolate* isolate, Handle<Map> map, |
| const char* reason); |
| static Handle<Map> Create(Isolate* isolate, int inobject_properties); |
| |
| // Returns the next free property index (only valid for FAST MODE). |
| int NextFreePropertyIndex() const; |
| |
| // Returns the number of enumerable properties. |
| int NumberOfEnumerableProperties() const; |
| |
| DECL_CAST2(Map) |
| |
| static inline int SlackForArraySize(int old_size, int size_limit); |
| |
| static void EnsureDescriptorSlack(Isolate* isolate, Handle<Map> map, |
| int slack); |
| |
| // Returns the map to be used for instances when the given {prototype} is |
| // passed to an Object.create call. Might transition the given {prototype}. |
| static Handle<Map> GetObjectCreateMap(Isolate* isolate, |
| Handle<HeapObject> prototype); |
| |
| // Similar to {GetObjectCreateMap} but does not transition {prototype} and |
| // fails gracefully by returning an empty handle instead. |
| static MaybeHandle<Map> TryGetObjectCreateMap(Isolate* isolate, |
| Handle<HeapObject> prototype); |
| |
| // Computes a hash value for this map, to be used in HashTables and such. |
| int Hash(); |
| |
| // Returns the transitioned map for this map with the most generic |
| // elements_kind that's found in |candidates|, or |nullptr| if no match is |
| // found at all. |
| Map FindElementsKindTransitionedMap(Isolate* isolate, |
| MapHandles const& candidates); |
| |
| inline bool CanTransition() const; |
| |
| #define DECL_TESTER(Type, ...) inline bool Is##Type##Map() const; |
| INSTANCE_TYPE_CHECKERS(DECL_TESTER) |
| #undef DECL_TESTER |
| inline bool IsBooleanMap() const; |
| inline bool IsNullOrUndefinedMap() const; |
| inline bool IsPrimitiveMap() const; |
| inline bool IsSpecialReceiverMap() const; |
| inline bool IsCustomElementsReceiverMap() const; |
| |
| bool IsMapInArrayPrototypeChain(Isolate* isolate) const; |
| |
| // Dispatched behavior. |
| void MapPrint(std::ostream& os); |
| DECL_VERIFIER(Map) |
| |
| #ifdef VERIFY_HEAP |
| void DictionaryMapVerify(Isolate* isolate); |
| #endif |
| |
| DECL_PRIMITIVE_ACCESSORS(visitor_id, VisitorId) |
| |
| static Handle<Map> TransitionToPrototype(Isolate* isolate, Handle<Map> map, |
| Handle<Object> prototype); |
| |
| static Handle<Map> TransitionToImmutableProto(Isolate* isolate, |
| Handle<Map> map); |
| |
| static const int kMaxPreAllocatedPropertyFields = 255; |
| |
| // Layout description. |
| #define MAP_FIELDS(V) \ |
| /* Raw data fields. */ \ |
| V(kInstanceSizeInWordsOffset, kUInt8Size) \ |
| V(kInObjectPropertiesStartOrConstructorFunctionIndexOffset, kUInt8Size) \ |
| V(kUsedOrUnusedInstanceSizeInWordsOffset, kUInt8Size) \ |
| V(kVisitorIdOffset, kUInt8Size) \ |
| V(kInstanceTypeOffset, kUInt16Size) \ |
| V(kBitFieldOffset, kUInt8Size) \ |
| V(kBitField2Offset, kUInt8Size) \ |
| V(kBitField3Offset, kUInt32Size) \ |
| V(k64BitArchPaddingOffset, \ |
| kSystemPointerSize == kUInt32Size ? 0 : kUInt32Size) \ |
| /* Pointer fields. */ \ |
| V(kPointerFieldsBeginOffset, 0) \ |
| V(kPrototypeOffset, kTaggedSize) \ |
| V(kConstructorOrBackPointerOffset, kTaggedSize) \ |
| V(kTransitionsOrPrototypeInfoOffset, kTaggedSize) \ |
| V(kDescriptorsOffset, kTaggedSize) \ |
| V(kLayoutDescriptorOffset, FLAG_unbox_double_fields ? kTaggedSize : 0) \ |
| V(kDependentCodeOffset, kTaggedSize) \ |
| V(kPrototypeValidityCellOffset, kTaggedSize) \ |
| V(kPointerFieldsEndOffset, 0) \ |
| /* Total size. */ \ |
| V(kSize, 0) |
| |
| DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, MAP_FIELDS) |
| #undef MAP_FIELDS |
| |
| STATIC_ASSERT(kInstanceTypeOffset == Internals::kMapInstanceTypeOffset); |
| |
| class BodyDescriptor; |
| |
| // Compares this map to another to see if they describe equivalent objects. |
| // If |mode| is set to CLEAR_INOBJECT_PROPERTIES, |other| is treated as if |
| // it had exactly zero inobject properties. |
| // The "shared" flags of both this map and |other| are ignored. |
| bool EquivalentToForNormalization(const Map other, |
| PropertyNormalizationMode mode) const; |
| |
| // Returns true if given field is unboxed double. |
| inline bool IsUnboxedDoubleField(FieldIndex index) const; |
| |
| void PrintMapDetails(std::ostream& os); |
| |
| static inline Handle<Map> AddMissingTransitionsForTesting( |
| Isolate* isolate, Handle<Map> split_map, |
| Handle<DescriptorArray> descriptors, |
| Handle<LayoutDescriptor> full_layout_descriptor); |
| |
| // Fires when the layout of an object with a leaf map changes. |
| // This includes adding transitions to the leaf map or changing |
| // the descriptor array. |
| inline void NotifyLeafMapLayoutChange(Isolate* isolate); |
| |
| static VisitorId GetVisitorId(Map map); |
| |
| // Returns true if objects with given instance type are allowed to have |
| // fast transitionable elements kinds. This predicate is used to ensure |
| // that objects that can have transitionable fast elements kind will not |
| // get in-place generalizable fields because the elements kind transition |
| // performed by stubs or optimized code can't properly generalize such |
| // fields. |
| static inline bool CanHaveFastTransitionableElementsKind( |
| InstanceType instance_type); |
| inline bool CanHaveFastTransitionableElementsKind() const; |
| |
| private: |
| // This byte encodes either the instance size without the in-object slack or |
| // the slack size in properties backing store. |
| // Let H be JSObject::kHeaderSize / kTaggedSize. |
| // If value >= H then: |
| // - all field properties are stored in the object. |
| // - there is no property array. |
| // - value * kTaggedSize is the actual object size without the slack. |
| // Otherwise: |
| // - there is no slack in the object. |
| // - the property array has value slack slots. |
| // Note that this encoding requires that H = JSObject::kFieldsAdded. |
| DECL_INT_ACCESSORS(used_or_unused_instance_size_in_words) |
| |
| // Returns the map that this (root) map transitions to if its elements_kind |
| // is changed to |elements_kind|, or |nullptr| if no such map is cached yet. |
| Map LookupElementsTransitionMap(Isolate* isolate, ElementsKind elements_kind); |
| |
| // Tries to replay property transitions starting from this (root) map using |
| // the descriptor array of the |map|. The |root_map| is expected to have |
| // proper elements kind and therefore elements kinds transitions are not |
| // taken by this function. Returns |nullptr| if matching transition map is |
| // not found. |
| Map TryReplayPropertyTransitions(Isolate* isolate, Map map); |
| |
| static void ConnectTransition(Isolate* isolate, Handle<Map> parent, |
| Handle<Map> child, Handle<Name> name, |
| SimpleTransitionFlag flag); |
| |
| bool EquivalentToForTransition(const Map other) const; |
| bool EquivalentToForElementsKindTransition(const Map other) const; |
| static Handle<Map> RawCopy(Isolate* isolate, Handle<Map> map, |
| int instance_size, int inobject_properties); |
| static Handle<Map> ShareDescriptor(Isolate* isolate, Handle<Map> map, |
| Handle<DescriptorArray> descriptors, |
| Descriptor* descriptor); |
| static Handle<Map> AddMissingTransitions( |
| Isolate* isolate, Handle<Map> map, Handle<DescriptorArray> descriptors, |
| Handle<LayoutDescriptor> full_layout_descriptor); |
| static void InstallDescriptors( |
| Isolate* isolate, Handle<Map> parent_map, Handle<Map> child_map, |
| int new_descriptor, Handle<DescriptorArray> descriptors, |
| Handle<LayoutDescriptor> full_layout_descriptor); |
| static Handle<Map> CopyAddDescriptor(Isolate* isolate, Handle<Map> map, |
| Descriptor* descriptor, |
| TransitionFlag flag); |
| static Handle<Map> CopyReplaceDescriptors( |
| Isolate* isolate, Handle<Map> map, Handle<DescriptorArray> descriptors, |
| Handle<LayoutDescriptor> layout_descriptor, TransitionFlag flag, |
| MaybeHandle<Name> maybe_name, const char* reason, |
| SimpleTransitionFlag simple_flag); |
| |
| static Handle<Map> CopyReplaceDescriptor(Isolate* isolate, Handle<Map> map, |
| Handle<DescriptorArray> descriptors, |
| Descriptor* descriptor, int index, |
| TransitionFlag flag); |
| static Handle<Map> CopyNormalized(Isolate* isolate, Handle<Map> map, |
| PropertyNormalizationMode mode); |
| |
| // TODO(ishell): Move to MapUpdater. |
| static Handle<Map> CopyGeneralizeAllFields(Isolate* isolate, Handle<Map> map, |
| ElementsKind elements_kind, |
| int modify_index, |
| PropertyKind kind, |
| PropertyAttributes attributes, |
| const char* reason); |
| |
| void DeprecateTransitionTree(Isolate* isolate); |
| |
| void ReplaceDescriptors(Isolate* isolate, DescriptorArray new_descriptors, |
| LayoutDescriptor new_layout_descriptor); |
| |
| // Update field type of the given descriptor to new representation and new |
| // type. The type must be prepared for storing in descriptor array: |
| // it must be either a simple type or a map wrapped in a weak cell. |
| void UpdateFieldType(Isolate* isolate, int descriptor_number, |
| Handle<Name> name, PropertyConstness new_constness, |
| Representation new_representation, |
| const MaybeObjectHandle& new_wrapped_type); |
| |
| // TODO(ishell): Move to MapUpdater. |
| void PrintReconfiguration(Isolate* isolate, FILE* file, int modify_index, |
| PropertyKind kind, PropertyAttributes attributes); |
| // TODO(ishell): Move to MapUpdater. |
| void PrintGeneralization( |
| Isolate* isolate, FILE* file, const char* reason, int modify_index, |
| int split, int descriptors, bool constant_to_field, |
| Representation old_representation, Representation new_representation, |
| MaybeHandle<FieldType> old_field_type, MaybeHandle<Object> old_value, |
| MaybeHandle<FieldType> new_field_type, MaybeHandle<Object> new_value); |
| |
| // Use the high-level instance_descriptors/SetInstanceDescriptors instead. |
| DECL_ACCESSORS2(raw_instance_descriptors, DescriptorArray) |
| |
| static const int kFastPropertiesSoftLimit = 12; |
| static const int kMaxFastProperties = 128; |
| |
| friend class MapUpdater; |
| |
| OBJECT_CONSTRUCTORS(Map, HeapObject); |
| }; |
| |
| // 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 WeakFixedArray { |
| public: |
| NEVER_READ_ONLY_SPACE |
| static Handle<NormalizedMapCache> New(Isolate* isolate); |
| |
| V8_WARN_UNUSED_RESULT MaybeHandle<Map> Get(Handle<Map> fast_map, |
| PropertyNormalizationMode mode); |
| void Set(Handle<Map> fast_map, Handle<Map> normalized_map); |
| |
| DECL_CAST2(NormalizedMapCache) |
| |
| static inline bool IsNormalizedMapCache(const HeapObject obj); |
| |
| DECL_VERIFIER(NormalizedMapCache) |
| |
| private: |
| static const int kEntries = 64; |
| |
| static inline int GetIndex(Handle<Map> map); |
| |
| // The following declarations hide base class methods. |
| Object* get(int index); |
| void set(int index, Object* value); |
| |
| OBJECT_CONSTRUCTORS(NormalizedMapCache, WeakFixedArray) |
| }; |
| |
| } // namespace internal |
| } // namespace v8 |
| |
| #include "src/objects/object-macros-undef.h" |
| |
| #endif // V8_OBJECTS_MAP_H_ |
