| // 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_INSTANCE_TYPE_H_ |
| #define V8_OBJECTS_INSTANCE_TYPE_H_ |
| |
| #include "src/objects/elements-kind.h" |
| #include "src/objects/objects-definitions.h" |
| |
| // Has to be the last include (doesn't have include guards): |
| #include "src/objects/object-macros.h" |
| #include "torque-generated/instance-types.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // We use the full 16 bits of the instance_type field to encode heap object |
| // instance types. All the high-order bits (bits 6-15) are cleared if the object |
| // is a string, and contain set bits if it is not a string. |
| const uint32_t kIsNotStringMask = ~((1 << 6) - 1); |
| const uint32_t kStringTag = 0x0; |
| |
| // For strings, bits 0-2 indicate the representation of the string. In |
| // particular, bit 0 indicates whether the string is direct or indirect. |
| const uint32_t kStringRepresentationMask = (1 << 3) - 1; |
| enum StringRepresentationTag { |
| kSeqStringTag = 0x0, |
| kConsStringTag = 0x1, |
| kExternalStringTag = 0x2, |
| kSlicedStringTag = 0x3, |
| kThinStringTag = 0x5 |
| }; |
| const uint32_t kIsIndirectStringMask = 1 << 0; |
| const uint32_t kIsIndirectStringTag = 1 << 0; |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((kSeqStringTag & kIsIndirectStringMask) == 0); |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((kExternalStringTag & kIsIndirectStringMask) == 0); |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((kConsStringTag & kIsIndirectStringMask) == kIsIndirectStringTag); |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((kSlicedStringTag & kIsIndirectStringMask) == |
| kIsIndirectStringTag); |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((kThinStringTag & kIsIndirectStringMask) == kIsIndirectStringTag); |
| |
| // For strings, bit 3 indicates whether the string consists of two-byte |
| // characters or one-byte characters. |
| const uint32_t kStringEncodingMask = 1 << 3; |
| const uint32_t kTwoByteStringTag = 0; |
| const uint32_t kOneByteStringTag = 1 << 3; |
| |
| // For strings, bit 4 indicates whether the data pointer of an external string |
| // is cached. Note that the string representation is expected to be |
| // kExternalStringTag. |
| const uint32_t kUncachedExternalStringMask = 1 << 4; |
| const uint32_t kUncachedExternalStringTag = 1 << 4; |
| |
| // For strings, bit 5 indicates that the string is internalized (if not set) or |
| // isn't (if set). |
| const uint32_t kIsNotInternalizedMask = 1 << 5; |
| const uint32_t kNotInternalizedTag = 1 << 5; |
| const uint32_t kInternalizedTag = 0; |
| |
| // A ConsString with an empty string as the right side is a candidate |
| // for being shortcut by the garbage collector. We don't allocate any |
| // non-flat internalized strings, so we do not shortcut them thereby |
| // avoiding turning internalized strings into strings. The bit-masks |
| // below contain the internalized bit as additional safety. |
| // See heap.cc, mark-compact.cc and objects-visiting.cc. |
| const uint32_t kShortcutTypeMask = |
| kIsNotStringMask | kIsNotInternalizedMask | kStringRepresentationMask; |
| const uint32_t kShortcutTypeTag = kConsStringTag | kNotInternalizedTag; |
| |
| static inline bool IsShortcutCandidate(int type) { |
| return ((type & kShortcutTypeMask) == kShortcutTypeTag); |
| } |
| |
| enum InstanceType : uint16_t { |
| // String types. |
| INTERNALIZED_STRING_TYPE = |
| kTwoByteStringTag | kSeqStringTag | kInternalizedTag, |
| ONE_BYTE_INTERNALIZED_STRING_TYPE = |
| kOneByteStringTag | kSeqStringTag | kInternalizedTag, |
| EXTERNAL_INTERNALIZED_STRING_TYPE = |
| kTwoByteStringTag | kExternalStringTag | kInternalizedTag, |
| EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE = |
| kOneByteStringTag | kExternalStringTag | kInternalizedTag, |
| UNCACHED_EXTERNAL_INTERNALIZED_STRING_TYPE = |
| EXTERNAL_INTERNALIZED_STRING_TYPE | kUncachedExternalStringTag | |
| kInternalizedTag, |
| UNCACHED_EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE = |
| EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE | kUncachedExternalStringTag | |
| kInternalizedTag, |
| STRING_TYPE = INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| ONE_BYTE_STRING_TYPE = |
| ONE_BYTE_INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| CONS_STRING_TYPE = kTwoByteStringTag | kConsStringTag | kNotInternalizedTag, |
| CONS_ONE_BYTE_STRING_TYPE = |
| kOneByteStringTag | kConsStringTag | kNotInternalizedTag, |
| SLICED_STRING_TYPE = |
| kTwoByteStringTag | kSlicedStringTag | kNotInternalizedTag, |
| SLICED_ONE_BYTE_STRING_TYPE = |
| kOneByteStringTag | kSlicedStringTag | kNotInternalizedTag, |
| EXTERNAL_STRING_TYPE = |
| EXTERNAL_INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| EXTERNAL_ONE_BYTE_STRING_TYPE = |
| EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| UNCACHED_EXTERNAL_STRING_TYPE = |
| UNCACHED_EXTERNAL_INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| UNCACHED_EXTERNAL_ONE_BYTE_STRING_TYPE = |
| UNCACHED_EXTERNAL_ONE_BYTE_INTERNALIZED_STRING_TYPE | kNotInternalizedTag, |
| THIN_STRING_TYPE = kTwoByteStringTag | kThinStringTag | kNotInternalizedTag, |
| THIN_ONE_BYTE_STRING_TYPE = |
| kOneByteStringTag | kThinStringTag | kNotInternalizedTag, |
| |
| // Most instance types are defined in Torque, with the exception of the string |
| // types above. They are ordered by inheritance hierarchy so that we can easily |
| // use range checks to determine whether an object is an instance of a subclass |
| // of any type. There are a few more constraints specified in the Torque type |
| // definitions: |
| // - Some instance types are exposed in v8.h, so they are locked to specific |
| // values to not unnecessarily change the ABI. |
| // - JSSpecialObject and JSCustomElementsObject are aligned with the beginning |
| // of the JSObject range, so that we can use a larger range check from |
| // FIRST_JS_RECEIVER_TYPE to the end of those ranges and include JSProxy too. |
| // - JSFunction is last, meaning we can use a single inequality check to |
| // determine whether an instance type is within the range for any class in the |
| // inheritance hierarchy of JSFunction. This includes commonly-checked classes |
| // JSObject and JSReceiver. |
| #define MAKE_TORQUE_INSTANCE_TYPE(TYPE, value) TYPE = value, |
| TORQUE_ASSIGNED_INSTANCE_TYPES(MAKE_TORQUE_INSTANCE_TYPE) |
| #undef MAKE_TORQUE_INSTANCE_TYPE |
| |
| // Pseudo-types |
| FIRST_UNIQUE_NAME_TYPE = INTERNALIZED_STRING_TYPE, |
| LAST_UNIQUE_NAME_TYPE = SYMBOL_TYPE, |
| FIRST_NONSTRING_TYPE = SYMBOL_TYPE, |
| // Boundary for testing JSReceivers that need special property lookup handling |
| LAST_SPECIAL_RECEIVER_TYPE = LAST_JS_SPECIAL_OBJECT_TYPE, |
| // Boundary case for testing JSReceivers that may have elements while having |
| // an empty fixed array as elements backing store. This is true for string |
| // wrappers. |
| LAST_CUSTOM_ELEMENTS_RECEIVER = LAST_JS_CUSTOM_ELEMENTS_OBJECT_TYPE, |
| |
| // Convenient names for things where the generated name is awkward: |
| FIRST_TYPE = FIRST_HEAP_OBJECT_TYPE, |
| LAST_TYPE = LAST_HEAP_OBJECT_TYPE, |
| FIRST_FUNCTION_TYPE = FIRST_JS_FUNCTION_OR_BOUND_FUNCTION_TYPE, |
| LAST_FUNCTION_TYPE = LAST_JS_FUNCTION_OR_BOUND_FUNCTION_TYPE, |
| BIGINT_TYPE = BIG_INT_BASE_TYPE, |
| }; |
| |
| // This constant is defined outside of the InstanceType enum because the |
| // string instance types are sparse and there's no such string instance type. |
| // But it's still useful for range checks to have such a value. |
| constexpr InstanceType LAST_STRING_TYPE = |
| static_cast<InstanceType>(FIRST_NONSTRING_TYPE - 1); |
| |
| // NOLINTNEXTLINE(runtime/references) (false positive) |
| STATIC_ASSERT((FIRST_NONSTRING_TYPE & kIsNotStringMask) != kStringTag); |
| STATIC_ASSERT(JS_OBJECT_TYPE == Internals::kJSObjectType); |
| STATIC_ASSERT(JS_API_OBJECT_TYPE == Internals::kJSApiObjectType); |
| STATIC_ASSERT(JS_SPECIAL_API_OBJECT_TYPE == Internals::kJSSpecialApiObjectType); |
| STATIC_ASSERT(FIRST_NONSTRING_TYPE == Internals::kFirstNonstringType); |
| STATIC_ASSERT(ODDBALL_TYPE == Internals::kOddballType); |
| STATIC_ASSERT(FOREIGN_TYPE == Internals::kForeignType); |
| |
| // Verify that string types are all less than other types. |
| #define CHECK_STRING_RANGE(TYPE, ...) \ |
| STATIC_ASSERT(TYPE < FIRST_NONSTRING_TYPE); |
| STRING_TYPE_LIST(CHECK_STRING_RANGE) |
| #undef CHECK_STRING_RANGE |
| #define CHECK_NONSTRING_RANGE(TYPE) STATIC_ASSERT(TYPE >= FIRST_NONSTRING_TYPE); |
| TORQUE_ASSIGNED_INSTANCE_TYPE_LIST(CHECK_NONSTRING_RANGE) |
| #undef CHECK_NONSTRING_RANGE |
| |
| // Two ranges don't cleanly follow the inheritance hierarchy. Here we ensure |
| // that only expected types fall within these ranges. |
| // - From FIRST_JS_RECEIVER_TYPE to LAST_SPECIAL_RECEIVER_TYPE should correspond |
| // to the union type JSProxy | JSSpecialObject. |
| // - From FIRST_JS_RECEIVER_TYPE to LAST_CUSTOM_ELEMENTS_RECEIVER should |
| // correspond to the union type JSProxy | JSCustomElementsObject. |
| // Note in particular that these ranges include all subclasses of JSReceiver |
| // that are not also subclasses of JSObject (currently only JSProxy). |
| #define CHECK_INSTANCE_TYPE(TYPE) \ |
| STATIC_ASSERT((TYPE >= FIRST_JS_RECEIVER_TYPE && \ |
| TYPE <= LAST_SPECIAL_RECEIVER_TYPE) == \ |
| (TYPE == JS_PROXY_TYPE || TYPE == JS_GLOBAL_OBJECT_TYPE || \ |
| TYPE == JS_GLOBAL_PROXY_TYPE || \ |
| TYPE == JS_MODULE_NAMESPACE_TYPE || \ |
| TYPE == JS_SPECIAL_API_OBJECT_TYPE)); \ |
| STATIC_ASSERT((TYPE >= FIRST_JS_RECEIVER_TYPE && \ |
| TYPE <= LAST_CUSTOM_ELEMENTS_RECEIVER) == \ |
| (TYPE == JS_PROXY_TYPE || TYPE == JS_GLOBAL_OBJECT_TYPE || \ |
| TYPE == JS_GLOBAL_PROXY_TYPE || \ |
| TYPE == JS_MODULE_NAMESPACE_TYPE || \ |
| TYPE == JS_SPECIAL_API_OBJECT_TYPE || \ |
| TYPE == JS_PRIMITIVE_WRAPPER_TYPE)); |
| TORQUE_ASSIGNED_INSTANCE_TYPE_LIST(CHECK_INSTANCE_TYPE) |
| #undef CHECK_INSTANCE_TYPE |
| |
| // Make sure it doesn't matter whether we sign-extend or zero-extend these |
| // values, because Torque treats InstanceType as signed. |
| STATIC_ASSERT(LAST_TYPE < 1 << 15); |
| |
| V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os, |
| InstanceType instance_type); |
| |
| // List of object types that have a single unique instance type. |
| #define INSTANCE_TYPE_CHECKERS_SINGLE(V) \ |
| TORQUE_INSTANCE_CHECKERS_SINGLE_FULLY_DEFINED(V) \ |
| TORQUE_INSTANCE_CHECKERS_SINGLE_ONLY_DECLARED(V) \ |
| V(BigInt, BIGINT_TYPE) \ |
| V(FixedArrayExact, FIXED_ARRAY_TYPE) |
| |
| #define INSTANCE_TYPE_CHECKERS_RANGE(V) \ |
| TORQUE_INSTANCE_CHECKERS_RANGE_FULLY_DEFINED(V) \ |
| TORQUE_INSTANCE_CHECKERS_RANGE_ONLY_DECLARED(V) |
| |
| #define INSTANCE_TYPE_CHECKERS_CUSTOM(V) \ |
| V(ExternalString) \ |
| V(InternalizedString) |
| |
| #define INSTANCE_TYPE_CHECKERS(V) \ |
| INSTANCE_TYPE_CHECKERS_SINGLE(V) \ |
| INSTANCE_TYPE_CHECKERS_RANGE(V) \ |
| INSTANCE_TYPE_CHECKERS_CUSTOM(V) |
| |
| namespace InstanceTypeChecker { |
| #define IS_TYPE_FUNCTION_DECL(Type, ...) \ |
| V8_INLINE bool Is##Type(InstanceType instance_type); |
| |
| INSTANCE_TYPE_CHECKERS(IS_TYPE_FUNCTION_DECL) |
| |
| #define TYPED_ARRAY_IS_TYPE_FUNCTION_DECL(Type, ...) \ |
| IS_TYPE_FUNCTION_DECL(Fixed##Type##Array) |
| TYPED_ARRAYS(TYPED_ARRAY_IS_TYPE_FUNCTION_DECL) |
| #undef TYPED_ARRAY_IS_TYPE_FUNCTION_DECL |
| |
| #undef IS_TYPE_FUNCTION_DECL |
| } // namespace InstanceTypeChecker |
| |
| // This list must contain only maps that are shared by all objects of their |
| // instance type. |
| #define UNIQUE_INSTANCE_TYPE_MAP_LIST_GENERATOR(V, _) \ |
| V(_, AccessorInfoMap, accessor_info_map, AccessorInfo) \ |
| V(_, AccessorPairMap, accessor_pair_map, AccessorPair) \ |
| V(_, AllocationMementoMap, allocation_memento_map, AllocationMemento) \ |
| V(_, ArrayBoilerplateDescriptionMap, array_boilerplate_description_map, \ |
| ArrayBoilerplateDescription) \ |
| V(_, BreakPointMap, break_point_map, BreakPoint) \ |
| V(_, BreakPointInfoMap, break_point_info_map, BreakPointInfo) \ |
| V(_, CachedTemplateObjectMap, cached_template_object_map, \ |
| CachedTemplateObject) \ |
| V(_, CellMap, cell_map, Cell) \ |
| V(_, WeakCellMap, weak_cell_map, WeakCell) \ |
| V(_, CodeMap, code_map, Code) \ |
| V(_, CoverageInfoMap, coverage_info_map, CoverageInfo) \ |
| V(_, DebugInfoMap, debug_info_map, DebugInfo) \ |
| V(_, FeedbackVectorMap, feedback_vector_map, FeedbackVector) \ |
| V(_, FixedDoubleArrayMap, fixed_double_array_map, FixedDoubleArray) \ |
| V(_, FunctionTemplateInfoMap, function_template_info_map, \ |
| FunctionTemplateInfo) \ |
| V(_, HeapNumberMap, heap_number_map, HeapNumber) \ |
| V(_, MetaMap, meta_map, Map) \ |
| V(_, PreparseDataMap, preparse_data_map, PreparseData) \ |
| V(_, PrototypeInfoMap, prototype_info_map, PrototypeInfo) \ |
| V(_, SharedFunctionInfoMap, shared_function_info_map, SharedFunctionInfo) \ |
| V(_, SmallOrderedHashSetMap, small_ordered_hash_set_map, \ |
| SmallOrderedHashSet) \ |
| V(_, SmallOrderedHashMapMap, small_ordered_hash_map_map, \ |
| SmallOrderedHashMap) \ |
| V(_, SmallOrderedNameDictionaryMap, small_ordered_name_dictionary_map, \ |
| SmallOrderedNameDictionary) \ |
| V(_, SymbolMap, symbol_map, Symbol) \ |
| V(_, TransitionArrayMap, transition_array_map, TransitionArray) \ |
| V(_, Tuple2Map, tuple2_map, Tuple2) \ |
| V(_, UncompiledDataWithoutPreparseDataMap, \ |
| uncompiled_data_without_preparse_data_map, \ |
| UncompiledDataWithoutPreparseData) \ |
| V(_, UncompiledDataWithPreparseDataMap, \ |
| uncompiled_data_with_preparse_data_map, UncompiledDataWithPreparseData) \ |
| V(_, WeakFixedArrayMap, weak_fixed_array_map, WeakFixedArray) \ |
| TORQUE_DEFINED_MAP_CSA_LIST_GENERATOR(V, _) |
| |
| } // namespace internal |
| } // namespace v8 |
| |
| #include "src/objects/object-macros-undef.h" |
| |
| #endif // V8_OBJECTS_INSTANCE_TYPE_H_ |
