| // Copyright 2012 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_PROPERTY_DETAILS_H_ |
| #define V8_OBJECTS_PROPERTY_DETAILS_H_ |
| |
| #include "include/v8.h" |
| #include "src/utils/allocation.h" |
| // TODO(bmeurer): Remove once FLAG_modify_field_representation_inplace is gone. |
| #include "src/base/bit-field.h" |
| #include "src/flags/flags.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // ES6 6.1.7.1 |
| enum PropertyAttributes { |
| NONE = ::v8::None, |
| READ_ONLY = ::v8::ReadOnly, |
| DONT_ENUM = ::v8::DontEnum, |
| DONT_DELETE = ::v8::DontDelete, |
| |
| ALL_ATTRIBUTES_MASK = READ_ONLY | DONT_ENUM | DONT_DELETE, |
| |
| SEALED = DONT_DELETE, |
| FROZEN = SEALED | READ_ONLY, |
| |
| ABSENT = 64, // Used in runtime to indicate a property is absent. |
| // ABSENT can never be stored in or returned from a descriptor's attributes |
| // bitfield. It is only used as a return value meaning the attributes of |
| // a non-existent property. |
| }; |
| |
| enum PropertyFilter { |
| ALL_PROPERTIES = 0, |
| ONLY_WRITABLE = 1, |
| ONLY_ENUMERABLE = 2, |
| ONLY_CONFIGURABLE = 4, |
| SKIP_STRINGS = 8, |
| SKIP_SYMBOLS = 16, |
| ONLY_ALL_CAN_READ = 32, |
| PRIVATE_NAMES_ONLY = 64, |
| ENUMERABLE_STRINGS = ONLY_ENUMERABLE | SKIP_SYMBOLS, |
| }; |
| // Enable fast comparisons of PropertyAttributes against PropertyFilters. |
| STATIC_ASSERT(ALL_PROPERTIES == static_cast<PropertyFilter>(NONE)); |
| STATIC_ASSERT(ONLY_WRITABLE == static_cast<PropertyFilter>(READ_ONLY)); |
| STATIC_ASSERT(ONLY_ENUMERABLE == static_cast<PropertyFilter>(DONT_ENUM)); |
| STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>(DONT_DELETE)); |
| STATIC_ASSERT(((SKIP_STRINGS | SKIP_SYMBOLS | ONLY_ALL_CAN_READ) & |
| ALL_ATTRIBUTES_MASK) == 0); |
| STATIC_ASSERT(ALL_PROPERTIES == |
| static_cast<PropertyFilter>(v8::PropertyFilter::ALL_PROPERTIES)); |
| STATIC_ASSERT(ONLY_WRITABLE == |
| static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_WRITABLE)); |
| STATIC_ASSERT(ONLY_ENUMERABLE == |
| static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_ENUMERABLE)); |
| STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>( |
| v8::PropertyFilter::ONLY_CONFIGURABLE)); |
| STATIC_ASSERT(SKIP_STRINGS == |
| static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_STRINGS)); |
| STATIC_ASSERT(SKIP_SYMBOLS == |
| static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_SYMBOLS)); |
| |
| class Smi; |
| class TypeInfo; |
| |
| // Order of kinds is significant. |
| // Must fit in the BitField PropertyDetails::KindField. |
| enum PropertyKind { kData = 0, kAccessor = 1 }; |
| |
| // Order of modes is significant. |
| // Must fit in the BitField PropertyDetails::LocationField. |
| enum PropertyLocation { kField = 0, kDescriptor = 1 }; |
| |
| // Order of modes is significant. |
| // Must fit in the BitField PropertyDetails::ConstnessField. |
| enum class PropertyConstness { kMutable = 0, kConst = 1 }; |
| |
| class Representation { |
| public: |
| enum Kind { kNone, kSmi, kDouble, kHeapObject, kTagged, kNumRepresentations }; |
| |
| Representation() : kind_(kNone) {} |
| |
| static Representation None() { return Representation(kNone); } |
| static Representation Tagged() { return Representation(kTagged); } |
| static Representation Smi() { return Representation(kSmi); } |
| static Representation Double() { return Representation(kDouble); } |
| static Representation HeapObject() { return Representation(kHeapObject); } |
| |
| static Representation FromKind(Kind kind) { return Representation(kind); } |
| |
| bool Equals(const Representation& other) const { |
| return kind_ == other.kind_; |
| } |
| |
| bool IsCompatibleForLoad(const Representation& other) const { |
| return IsDouble() == other.IsDouble(); |
| } |
| |
| bool IsCompatibleForStore(const Representation& other) const { |
| return Equals(other); |
| } |
| |
| bool CanBeInPlaceChangedTo(const Representation& other) const { |
| // If it's just a representation generalization case (i.e. property kind and |
| // attributes stays unchanged) it's fine to transition from None to anything |
| // but double without any modification to the object, because the default |
| // uninitialized value for representation None can be overwritten by both |
| // smi and tagged values. Doubles, however, would require a box allocation. |
| if (IsNone()) return !other.IsDouble(); |
| if (!FLAG_modify_field_representation_inplace) return false; |
| return (IsSmi() || (!FLAG_unbox_double_fields && IsDouble()) || |
| IsHeapObject()) && |
| other.IsTagged(); |
| } |
| |
| // Return the most generic representation that this representation can be |
| // changed to in-place. If in-place representation changes are disabled, then |
| // this will return the current representation. |
| Representation MostGenericInPlaceChange() const { |
| if (!FLAG_modify_field_representation_inplace) return *this; |
| // Everything but unboxed doubles can be in-place changed to Tagged. |
| if (FLAG_unbox_double_fields && IsDouble()) return Representation::Double(); |
| return Representation::Tagged(); |
| } |
| |
| bool is_more_general_than(const Representation& other) const { |
| if (IsHeapObject()) return other.IsNone(); |
| return kind_ > other.kind_; |
| } |
| |
| bool fits_into(const Representation& other) const { |
| return other.is_more_general_than(*this) || other.Equals(*this); |
| } |
| |
| Representation generalize(Representation other) { |
| if (other.fits_into(*this)) return *this; |
| if (other.is_more_general_than(*this)) return other; |
| return Representation::Tagged(); |
| } |
| |
| int size() const { |
| DCHECK(!IsNone()); |
| if (IsDouble()) return kDoubleSize; |
| DCHECK(IsTagged() || IsSmi() || IsHeapObject()); |
| return kTaggedSize; |
| } |
| |
| Kind kind() const { return static_cast<Kind>(kind_); } |
| bool IsNone() const { return kind_ == kNone; } |
| bool IsTagged() const { return kind_ == kTagged; } |
| bool IsSmi() const { return kind_ == kSmi; } |
| bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); } |
| bool IsDouble() const { return kind_ == kDouble; } |
| bool IsHeapObject() const { return kind_ == kHeapObject; } |
| |
| const char* Mnemonic() const { |
| switch (kind_) { |
| case kNone: |
| return "v"; |
| case kTagged: |
| return "t"; |
| case kSmi: |
| return "s"; |
| case kDouble: |
| return "d"; |
| case kHeapObject: |
| return "h"; |
| } |
| UNREACHABLE(); |
| } |
| |
| private: |
| explicit Representation(Kind k) : kind_(k) {} |
| |
| // Make sure kind fits in int8. |
| STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte)); |
| |
| int8_t kind_; |
| }; |
| |
| static const int kDescriptorIndexBitCount = 10; |
| static const int kFirstInobjectPropertyOffsetBitCount = 7; |
| // The maximum number of descriptors we want in a descriptor array. It should |
| // fit in a page and also the following should hold: |
| // kMaxNumberOfDescriptors + kFieldsAdded <= PropertyArray::kMaxLength. |
| static const int kMaxNumberOfDescriptors = (1 << kDescriptorIndexBitCount) - 4; |
| static const int kInvalidEnumCacheSentinel = |
| (1 << kDescriptorIndexBitCount) - 1; |
| |
| enum class PropertyCellType { |
| // Meaningful when a property cell does not contain the hole. |
| kUndefined, // The PREMONOMORPHIC of property cells. |
| kConstant, // Cell has been assigned only once. |
| kConstantType, // Cell has been assigned only one type. |
| kMutable, // Cell will no longer be tracked as constant. |
| |
| // Meaningful when a property cell contains the hole. |
| kUninitialized = kUndefined, // Cell has never been initialized. |
| kInvalidated = kConstant, // Cell has been deleted, invalidated or never |
| // existed. |
| |
| // For dictionaries not holding cells. |
| kNoCell = kMutable, |
| }; |
| |
| enum class PropertyCellConstantType { |
| kSmi, |
| kStableMap, |
| }; |
| |
| // PropertyDetails captures type and attributes for a property. |
| // They are used both in property dictionaries and instance descriptors. |
| class PropertyDetails { |
| public: |
| // Property details for dictionary mode properties/elements. |
| PropertyDetails(PropertyKind kind, PropertyAttributes attributes, |
| PropertyCellType cell_type, int dictionary_index = 0) { |
| value_ = KindField::encode(kind) | LocationField::encode(kField) | |
| AttributesField::encode(attributes) | |
| DictionaryStorageField::encode(dictionary_index) | |
| PropertyCellTypeField::encode(cell_type); |
| } |
| |
| // Property details for fast mode properties. |
| PropertyDetails(PropertyKind kind, PropertyAttributes attributes, |
| PropertyLocation location, PropertyConstness constness, |
| Representation representation, int field_index = 0) { |
| value_ = KindField::encode(kind) | AttributesField::encode(attributes) | |
| LocationField::encode(location) | |
| ConstnessField::encode(constness) | |
| RepresentationField::encode(EncodeRepresentation(representation)) | |
| FieldIndexField::encode(field_index); |
| } |
| |
| static PropertyDetails Empty( |
| PropertyCellType cell_type = PropertyCellType::kNoCell) { |
| return PropertyDetails(kData, NONE, cell_type); |
| } |
| |
| int pointer() const { return DescriptorPointer::decode(value_); } |
| |
| PropertyDetails set_pointer(int i) const { |
| return PropertyDetails(value_, i); |
| } |
| |
| PropertyDetails set_cell_type(PropertyCellType type) const { |
| PropertyDetails details = *this; |
| details.value_ = PropertyCellTypeField::update(details.value_, type); |
| return details; |
| } |
| |
| PropertyDetails set_index(int index) const { |
| PropertyDetails details = *this; |
| details.value_ = DictionaryStorageField::update(details.value_, index); |
| return details; |
| } |
| |
| PropertyDetails CopyWithRepresentation(Representation representation) const { |
| return PropertyDetails(value_, representation); |
| } |
| PropertyDetails CopyWithConstness(PropertyConstness constness) const { |
| return PropertyDetails(value_, constness); |
| } |
| PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) const { |
| new_attributes = |
| static_cast<PropertyAttributes>(attributes() | new_attributes); |
| return PropertyDetails(value_, new_attributes); |
| } |
| |
| // Conversion for storing details as Object. |
| explicit inline PropertyDetails(Smi smi); |
| inline Smi AsSmi() const; |
| |
| static uint8_t EncodeRepresentation(Representation representation) { |
| return representation.kind(); |
| } |
| |
| static Representation DecodeRepresentation(uint32_t bits) { |
| return Representation::FromKind(static_cast<Representation::Kind>(bits)); |
| } |
| |
| PropertyKind kind() const { return KindField::decode(value_); } |
| PropertyLocation location() const { return LocationField::decode(value_); } |
| PropertyConstness constness() const { return ConstnessField::decode(value_); } |
| |
| PropertyAttributes attributes() const { |
| return AttributesField::decode(value_); |
| } |
| |
| bool HasKindAndAttributes(PropertyKind kind, PropertyAttributes attributes) { |
| return (value_ & (KindField::kMask | AttributesField::kMask)) == |
| (KindField::encode(kind) | AttributesField::encode(attributes)); |
| } |
| |
| int dictionary_index() const { |
| return DictionaryStorageField::decode(value_); |
| } |
| |
| Representation representation() const { |
| return DecodeRepresentation(RepresentationField::decode(value_)); |
| } |
| |
| int field_index() const { return FieldIndexField::decode(value_); } |
| |
| inline int field_width_in_words() const; |
| |
| static bool IsValidIndex(int index) { |
| return DictionaryStorageField::is_valid(index); |
| } |
| |
| bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; } |
| bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; } |
| bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; } |
| bool IsEnumerable() const { return !IsDontEnum(); } |
| PropertyCellType cell_type() const { |
| return PropertyCellTypeField::decode(value_); |
| } |
| |
| // Bit fields in value_ (type, shift, size). Must be public so the |
| // constants can be embedded in generated code. |
| using KindField = base::BitField<PropertyKind, 0, 1>; |
| using LocationField = KindField::Next<PropertyLocation, 1>; |
| using ConstnessField = LocationField::Next<PropertyConstness, 1>; |
| using AttributesField = ConstnessField::Next<PropertyAttributes, 3>; |
| static const int kAttributesReadOnlyMask = |
| (READ_ONLY << AttributesField::kShift); |
| static const int kAttributesDontDeleteMask = |
| (DONT_DELETE << AttributesField::kShift); |
| static const int kAttributesDontEnumMask = |
| (DONT_ENUM << AttributesField::kShift); |
| |
| // Bit fields for normalized objects. |
| using PropertyCellTypeField = AttributesField::Next<PropertyCellType, 2>; |
| using DictionaryStorageField = PropertyCellTypeField::Next<uint32_t, 23>; |
| |
| // Bit fields for fast objects. |
| using RepresentationField = AttributesField::Next<uint32_t, 3>; |
| using DescriptorPointer = |
| RepresentationField::Next<uint32_t, kDescriptorIndexBitCount>; |
| using FieldIndexField = |
| DescriptorPointer::Next<uint32_t, kDescriptorIndexBitCount>; |
| |
| // All bits for both fast and slow objects must fit in a smi. |
| STATIC_ASSERT(DictionaryStorageField::kLastUsedBit < 31); |
| STATIC_ASSERT(FieldIndexField::kLastUsedBit < 31); |
| |
| static const int kInitialIndex = 1; |
| |
| #ifdef OBJECT_PRINT |
| // For our gdb macros, we should perhaps change these in the future. |
| void Print(bool dictionary_mode); |
| #endif |
| |
| enum PrintMode { |
| kPrintAttributes = 1 << 0, |
| kPrintFieldIndex = 1 << 1, |
| kPrintRepresentation = 1 << 2, |
| kPrintPointer = 1 << 3, |
| |
| kForProperties = kPrintFieldIndex, |
| kForTransitions = kPrintAttributes, |
| kPrintFull = -1, |
| }; |
| void PrintAsSlowTo(std::ostream& out); |
| void PrintAsFastTo(std::ostream& out, PrintMode mode = kPrintFull); |
| |
| private: |
| PropertyDetails(int value, int pointer) { |
| value_ = DescriptorPointer::update(value, pointer); |
| } |
| PropertyDetails(int value, Representation representation) { |
| value_ = RepresentationField::update(value, |
| EncodeRepresentation(representation)); |
| } |
| PropertyDetails(int value, PropertyConstness constness) { |
| value_ = ConstnessField::update(value, constness); |
| } |
| PropertyDetails(int value, PropertyAttributes attributes) { |
| value_ = AttributesField::update(value, attributes); |
| } |
| |
| uint32_t value_; |
| }; |
| |
| // kField location is more general than kDescriptor, kDescriptor generalizes |
| // only to itself. |
| inline bool IsGeneralizableTo(PropertyLocation a, PropertyLocation b) { |
| return b == kField || a == kDescriptor; |
| } |
| |
| // PropertyConstness::kMutable constness is more general than |
| // VariableMode::kConst, VariableMode::kConst generalizes only to itself. |
| inline bool IsGeneralizableTo(PropertyConstness a, PropertyConstness b) { |
| return b == PropertyConstness::kMutable || a == PropertyConstness::kConst; |
| } |
| |
| inline PropertyConstness GeneralizeConstness(PropertyConstness a, |
| PropertyConstness b) { |
| return a == PropertyConstness::kMutable ? PropertyConstness::kMutable : b; |
| } |
| |
| V8_EXPORT_PRIVATE std::ostream& operator<<( |
| std::ostream& os, const PropertyAttributes& attributes); |
| V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os, |
| PropertyConstness constness); |
| } // namespace internal |
| } // namespace v8 |
| |
| #endif // V8_OBJECTS_PROPERTY_DETAILS_H_ |