1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef V8_PROPERTY_DETAILS_H_
6 #define V8_PROPERTY_DETAILS_H_
8 #include "include/v8.h"
9 #include "src/allocation.h"
10 #include "src/utils.h"
13 enum PropertyAttributes {
15 READ_ONLY = v8::ReadOnly,
16 DONT_ENUM = v8::DontEnum,
17 DONT_DELETE = v8::DontDelete,
20 FROZEN = SEALED | READ_ONLY,
22 STRING = 8, // Used to filter symbols and string names
26 DONT_SHOW = DONT_ENUM | SYMBOLIC | PRIVATE_SYMBOL,
27 ABSENT = 64 // Used in runtime to indicate a property is absent.
28 // ABSENT can never be stored in or returned from a descriptor's attributes
29 // bitfield. It is only used as a return value meaning the attributes of
30 // a non-existent property.
38 template<class> class TypeImpl;
39 struct ZoneTypeConfig;
40 typedef TypeImpl<ZoneTypeConfig> Type;
43 // Type of properties.
44 // Order of kinds is significant.
45 // Must fit in the BitField PropertyDetails::KindField.
46 enum PropertyKind { kData = 0, kAccessor = 1 };
49 // Order of modes is significant.
50 // Must fit in the BitField PropertyDetails::StoreModeField.
51 enum PropertyLocation { kField = 0, kDescriptor = 1 };
54 // Order of properties is significant.
55 // Must fit in the BitField PropertyDetails::TypeField.
56 // A copy of this is in debug/mirrors.js.
58 DATA = (kField << 1) | kData,
59 DATA_CONSTANT = (kDescriptor << 1) | kData,
60 ACCESSOR = (kField << 1) | kAccessor,
61 ACCESSOR_CONSTANT = (kDescriptor << 1) | kAccessor
65 class Representation {
82 Representation() : kind_(kNone) { }
84 static Representation None() { return Representation(kNone); }
85 static Representation Tagged() { return Representation(kTagged); }
86 static Representation Integer8() { return Representation(kInteger8); }
87 static Representation UInteger8() { return Representation(kUInteger8); }
88 static Representation Integer16() { return Representation(kInteger16); }
89 static Representation UInteger16() { return Representation(kUInteger16); }
90 static Representation Smi() { return Representation(kSmi); }
91 static Representation Integer32() { return Representation(kInteger32); }
92 static Representation Double() { return Representation(kDouble); }
93 static Representation HeapObject() { return Representation(kHeapObject); }
94 static Representation External() { return Representation(kExternal); }
96 static Representation FromKind(Kind kind) { return Representation(kind); }
98 bool Equals(const Representation& other) const {
99 return kind_ == other.kind_;
102 bool IsCompatibleForLoad(const Representation& other) const {
103 return (IsDouble() && other.IsDouble()) ||
104 (!IsDouble() && !other.IsDouble());
107 bool IsCompatibleForStore(const Representation& other) const {
108 return Equals(other);
111 bool is_more_general_than(const Representation& other) const {
112 if (kind_ == kExternal && other.kind_ == kNone) return true;
113 if (kind_ == kExternal && other.kind_ == kExternal) return false;
114 if (kind_ == kNone && other.kind_ == kExternal) return false;
116 DCHECK(kind_ != kExternal);
117 DCHECK(other.kind_ != kExternal);
118 if (IsHeapObject()) return other.IsNone();
119 if (kind_ == kUInteger8 && other.kind_ == kInteger8) return false;
120 if (kind_ == kUInteger16 && other.kind_ == kInteger16) return false;
121 return kind_ > other.kind_;
124 bool fits_into(const Representation& other) const {
125 return other.is_more_general_than(*this) || other.Equals(*this);
128 Representation generalize(Representation other) {
129 if (other.fits_into(*this)) return *this;
130 if (other.is_more_general_than(*this)) return other;
131 return Representation::Tagged();
136 if (IsInteger8() || IsUInteger8()) {
137 return sizeof(uint8_t);
139 if (IsInteger16() || IsUInteger16()) {
140 return sizeof(uint16_t);
143 return sizeof(uint32_t);
148 Kind kind() const { return static_cast<Kind>(kind_); }
149 bool IsNone() const { return kind_ == kNone; }
150 bool IsInteger8() const { return kind_ == kInteger8; }
151 bool IsUInteger8() const { return kind_ == kUInteger8; }
152 bool IsInteger16() const { return kind_ == kInteger16; }
153 bool IsUInteger16() const { return kind_ == kUInteger16; }
154 bool IsTagged() const { return kind_ == kTagged; }
155 bool IsSmi() const { return kind_ == kSmi; }
156 bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); }
157 bool IsInteger32() const { return kind_ == kInteger32; }
158 bool IsSmiOrInteger32() const { return IsSmi() || IsInteger32(); }
159 bool IsDouble() const { return kind_ == kDouble; }
160 bool IsHeapObject() const { return kind_ == kHeapObject; }
161 bool IsExternal() const { return kind_ == kExternal; }
162 bool IsSpecialization() const {
163 return IsInteger8() || IsUInteger8() ||
164 IsInteger16() || IsUInteger16() ||
165 IsSmi() || IsInteger32() || IsDouble();
167 const char* Mnemonic() const;
170 explicit Representation(Kind k) : kind_(k) { }
172 // Make sure kind fits in int8.
173 STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte));
179 static const int kDescriptorIndexBitCount = 10;
180 // The maximum number of descriptors we want in a descriptor array (should
182 static const int kMaxNumberOfDescriptors =
183 (1 << kDescriptorIndexBitCount) - 2;
184 static const int kInvalidEnumCacheSentinel =
185 (1 << kDescriptorIndexBitCount) - 1;
188 enum class PropertyCellType {
189 // Meaningful when a property cell does not contain the hole.
190 kUndefined, // The PREMONOMORPHIC of property cells.
191 kConstant, // Cell has been assigned only once.
192 kConstantType, // Cell has been assigned only one type.
193 kMutable, // Cell will no longer be tracked as constant.
195 // Meaningful when a property cell contains the hole.
196 kUninitialized = kUndefined, // Cell has never been initialized.
197 kInvalidated = kConstant, // Cell has been deleted or invalidated.
199 // For dictionaries not holding cells.
204 enum class PropertyCellConstantType {
210 // PropertyDetails captures type and attributes for a property.
211 // They are used both in property dictionaries and instance descriptors.
212 class PropertyDetails BASE_EMBEDDED {
214 PropertyDetails(PropertyAttributes attributes, PropertyType type, int index,
215 PropertyCellType cell_type) {
216 value_ = TypeField::encode(type) | AttributesField::encode(attributes) |
217 DictionaryStorageField::encode(index) |
218 PropertyCellTypeField::encode(cell_type);
220 DCHECK(type == this->type());
221 DCHECK(attributes == this->attributes());
224 PropertyDetails(PropertyAttributes attributes,
226 Representation representation,
227 int field_index = 0) {
228 value_ = TypeField::encode(type)
229 | AttributesField::encode(attributes)
230 | RepresentationField::encode(EncodeRepresentation(representation))
231 | FieldIndexField::encode(field_index);
234 PropertyDetails(PropertyAttributes attributes, PropertyKind kind,
235 PropertyLocation location, Representation representation,
236 int field_index = 0) {
237 value_ = KindField::encode(kind) | LocationField::encode(location) |
238 AttributesField::encode(attributes) |
239 RepresentationField::encode(EncodeRepresentation(representation)) |
240 FieldIndexField::encode(field_index);
243 static PropertyDetails Empty() {
244 return PropertyDetails(NONE, DATA, 0, PropertyCellType::kNoCell);
247 int pointer() const { return DescriptorPointer::decode(value_); }
249 PropertyDetails set_pointer(int i) const {
250 return PropertyDetails(value_, i);
253 PropertyDetails set_cell_type(PropertyCellType type) const {
254 PropertyDetails details = *this;
255 details.value_ = PropertyCellTypeField::update(details.value_, type);
259 PropertyDetails set_index(int index) const {
260 PropertyDetails details = *this;
261 details.value_ = DictionaryStorageField::update(details.value_, index);
265 PropertyDetails CopyWithRepresentation(Representation representation) const {
266 return PropertyDetails(value_, representation);
268 PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) const {
270 static_cast<PropertyAttributes>(attributes() | new_attributes);
271 return PropertyDetails(value_, new_attributes);
274 // Conversion for storing details as Object*.
275 explicit inline PropertyDetails(Smi* smi);
276 inline Smi* AsSmi() const;
278 static uint8_t EncodeRepresentation(Representation representation) {
279 return representation.kind();
282 static Representation DecodeRepresentation(uint32_t bits) {
283 return Representation::FromKind(static_cast<Representation::Kind>(bits));
286 PropertyKind kind() const { return KindField::decode(value_); }
287 PropertyLocation location() const { return LocationField::decode(value_); }
289 PropertyType type() const { return TypeField::decode(value_); }
291 PropertyAttributes attributes() const {
292 return AttributesField::decode(value_);
295 int dictionary_index() const {
296 return DictionaryStorageField::decode(value_);
299 Representation representation() const {
300 return DecodeRepresentation(RepresentationField::decode(value_));
303 int field_index() const { return FieldIndexField::decode(value_); }
305 inline int field_width_in_words() const;
307 static bool IsValidIndex(int index) {
308 return DictionaryStorageField::is_valid(index);
311 bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
312 bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; }
313 bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
314 PropertyCellType cell_type() const {
315 return PropertyCellTypeField::decode(value_);
318 // Bit fields in value_ (type, shift, size). Must be public so the
319 // constants can be embedded in generated code.
320 class KindField : public BitField<PropertyKind, 0, 1> {};
321 class LocationField : public BitField<PropertyLocation, 1, 1> {};
322 class AttributesField : public BitField<PropertyAttributes, 2, 3> {};
323 static const int kAttributesReadOnlyMask =
324 (READ_ONLY << AttributesField::kShift);
326 // Bit fields for normalized objects.
327 class PropertyCellTypeField : public BitField<PropertyCellType, 5, 2> {};
328 class DictionaryStorageField : public BitField<uint32_t, 7, 24> {};
330 // Bit fields for fast objects.
331 class RepresentationField : public BitField<uint32_t, 5, 4> {};
332 class DescriptorPointer
333 : public BitField<uint32_t, 9, kDescriptorIndexBitCount> {}; // NOLINT
334 class FieldIndexField
335 : public BitField<uint32_t, 9 + kDescriptorIndexBitCount,
336 kDescriptorIndexBitCount> {}; // NOLINT
338 // NOTE: TypeField overlaps with KindField and LocationField.
339 class TypeField : public BitField<PropertyType, 0, 2> {};
340 STATIC_ASSERT(KindField::kNext == LocationField::kShift);
341 STATIC_ASSERT(TypeField::kShift == KindField::kShift);
342 STATIC_ASSERT(TypeField::kNext == LocationField::kNext);
344 // All bits for both fast and slow objects must fit in a smi.
345 STATIC_ASSERT(DictionaryStorageField::kNext <= 31);
346 STATIC_ASSERT(FieldIndexField::kNext <= 31);
348 static const int kInitialIndex = 1;
351 // For our gdb macros, we should perhaps change these in the future.
352 void Print(bool dictionary_mode);
356 PropertyDetails(int value, int pointer) {
357 value_ = DescriptorPointer::update(value, pointer);
359 PropertyDetails(int value, Representation representation) {
360 value_ = RepresentationField::update(
361 value, EncodeRepresentation(representation));
363 PropertyDetails(int value, PropertyAttributes attributes) {
364 value_ = AttributesField::update(value, attributes);
371 std::ostream& operator<<(std::ostream& os,
372 const PropertyAttributes& attributes);
373 std::ostream& operator<<(std::ostream& os, const PropertyDetails& details);
374 } } // namespace v8::internal
376 #endif // V8_PROPERTY_DETAILS_H_