// 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_PROPERTY_DETAILS_H_ #define V8_PROPERTY_DETAILS_H_ #include "include/v8.h" #include "src/allocation.h" // TODO(ishell): remove once FLAG_track_constant_fields is removed. #include "src/flags.h" #include "src/utils.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, 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 PropertyConstness { kMutable = 0, kConst = 1 }; // TODO(ishell): remove once constant field tracking is done. const PropertyConstness kDefaultFieldConstness = FLAG_track_constant_fields ? kConst : kMutable; class Representation { public: enum Kind { kNone, kInteger8, kUInteger8, kInteger16, kUInteger16, kSmi, kInteger32, kDouble, kHeapObject, kTagged, kExternal, kNumRepresentations }; Representation() : kind_(kNone) { } static Representation None() { return Representation(kNone); } static Representation Tagged() { return Representation(kTagged); } static Representation Integer8() { return Representation(kInteger8); } static Representation UInteger8() { return Representation(kUInteger8); } static Representation Integer16() { return Representation(kInteger16); } static Representation UInteger16() { return Representation(kUInteger16); } static Representation Smi() { return Representation(kSmi); } static Representation Integer32() { return Representation(kInteger32); } static Representation Double() { return Representation(kDouble); } static Representation HeapObject() { return Representation(kHeapObject); } static Representation External() { return Representation(kExternal); } 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()) || (!IsDouble() && !other.IsDouble()); } bool IsCompatibleForStore(const Representation& other) const { return Equals(other); } bool is_more_general_than(const Representation& other) const { if (kind_ == kExternal && other.kind_ == kNone) return true; if (kind_ == kExternal && other.kind_ == kExternal) return false; if (kind_ == kNone && other.kind_ == kExternal) return false; DCHECK_NE(kind_, kExternal); DCHECK_NE(other.kind_, kExternal); if (IsHeapObject()) return other.IsNone(); if (kind_ == kUInteger8 && other.kind_ == kInteger8) return false; if (kind_ == kUInteger16 && other.kind_ == kInteger16) return false; 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 (IsInteger8() || IsUInteger8()) { return sizeof(uint8_t); } if (IsInteger16() || IsUInteger16()) { return sizeof(uint16_t); } if (IsInteger32()) { return sizeof(uint32_t); } return kPointerSize; } Kind kind() const { return static_cast<Kind>(kind_); } bool IsNone() const { return kind_ == kNone; } bool IsInteger8() const { return kind_ == kInteger8; } bool IsUInteger8() const { return kind_ == kUInteger8; } bool IsInteger16() const { return kind_ == kInteger16; } bool IsUInteger16() const { return kind_ == kUInteger16; } bool IsTagged() const { return kind_ == kTagged; } bool IsSmi() const { return kind_ == kSmi; } bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); } bool IsInteger32() const { return kind_ == kInteger32; } bool IsSmiOrInteger32() const { return IsSmi() || IsInteger32(); } bool IsDouble() const { return kind_ == kDouble; } bool IsHeapObject() const { return kind_ == kHeapObject; } bool IsExternal() const { return kind_ == kExternal; } bool IsSpecialization() const { return IsInteger8() || IsUInteger8() || IsInteger16() || IsUInteger16() || IsSmi() || IsInteger32() || IsDouble(); } const char* Mnemonic() const; 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; // 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 BASE_EMBEDDED { 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_); } 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. class KindField : public BitField<PropertyKind, 0, 1> {}; class LocationField : public BitField<PropertyLocation, KindField::kNext, 1> { }; class ConstnessField : public BitField<PropertyConstness, LocationField::kNext, 1> {}; class AttributesField : public BitField<PropertyAttributes, ConstnessField::kNext, 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. class PropertyCellTypeField : public BitField<PropertyCellType, AttributesField::kNext, 2> {}; class DictionaryStorageField : public BitField<uint32_t, PropertyCellTypeField::kNext, 23> {}; // Bit fields for fast objects. class RepresentationField : public BitField<uint32_t, AttributesField::kNext, 4> {}; class DescriptorPointer : public BitField<uint32_t, RepresentationField::kNext, kDescriptorIndexBitCount> {}; // NOLINT class FieldIndexField : public BitField<uint32_t, DescriptorPointer::kNext, kDescriptorIndexBitCount> { }; // NOLINT // All bits for both fast and slow objects must fit in a smi. STATIC_ASSERT(DictionaryStorageField::kNext <= 31); STATIC_ASSERT(FieldIndexField::kNext <= 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; } // kMutable constness is more general than kConst, kConst generalizes only to // itself. inline bool IsGeneralizableTo(PropertyConstness a, PropertyConstness b) { return b == kMutable || a == kConst; } inline PropertyConstness GeneralizeConstness(PropertyConstness a, PropertyConstness b) { return a == kMutable ? kMutable : b; } std::ostream& operator<<(std::ostream& os, const PropertyAttributes& attributes); } // namespace internal } // namespace v8 #endif // V8_PROPERTY_DETAILS_H_