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 mirror-debugger.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 static Representation FromType(Type* type);
100 bool Equals(const Representation& other) const {
101 return kind_ == other.kind_;
104 bool IsCompatibleForLoad(const Representation& other) const {
105 return (IsDouble() && other.IsDouble()) ||
106 (!IsDouble() && !other.IsDouble());
109 bool IsCompatibleForStore(const Representation& other) const {
110 return Equals(other);
113 bool is_more_general_than(const Representation& other) const {
114 if (kind_ == kExternal && other.kind_ == kNone) return true;
115 if (kind_ == kExternal && other.kind_ == kExternal) return false;
116 if (kind_ == kNone && other.kind_ == kExternal) return false;
118 DCHECK(kind_ != kExternal);
119 DCHECK(other.kind_ != kExternal);
120 if (IsHeapObject()) return other.IsNone();
121 if (kind_ == kUInteger8 && other.kind_ == kInteger8) return false;
122 if (kind_ == kUInteger16 && other.kind_ == kInteger16) return false;
123 return kind_ > other.kind_;
126 bool fits_into(const Representation& other) const {
127 return other.is_more_general_than(*this) || other.Equals(*this);
130 Representation generalize(Representation other) {
131 if (other.fits_into(*this)) return *this;
132 if (other.is_more_general_than(*this)) return other;
133 return Representation::Tagged();
138 if (IsInteger8() || IsUInteger8()) {
139 return sizeof(uint8_t);
141 if (IsInteger16() || IsUInteger16()) {
142 return sizeof(uint16_t);
145 return sizeof(uint32_t);
150 Kind kind() const { return static_cast<Kind>(kind_); }
151 bool IsNone() const { return kind_ == kNone; }
152 bool IsInteger8() const { return kind_ == kInteger8; }
153 bool IsUInteger8() const { return kind_ == kUInteger8; }
154 bool IsInteger16() const { return kind_ == kInteger16; }
155 bool IsUInteger16() const { return kind_ == kUInteger16; }
156 bool IsTagged() const { return kind_ == kTagged; }
157 bool IsSmi() const { return kind_ == kSmi; }
158 bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); }
159 bool IsInteger32() const { return kind_ == kInteger32; }
160 bool IsSmiOrInteger32() const { return IsSmi() || IsInteger32(); }
161 bool IsDouble() const { return kind_ == kDouble; }
162 bool IsHeapObject() const { return kind_ == kHeapObject; }
163 bool IsExternal() const { return kind_ == kExternal; }
164 bool IsSpecialization() const {
165 return IsInteger8() || IsUInteger8() ||
166 IsInteger16() || IsUInteger16() ||
167 IsSmi() || IsInteger32() || IsDouble();
169 const char* Mnemonic() const;
172 explicit Representation(Kind k) : kind_(k) { }
174 // Make sure kind fits in int8.
175 STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte));
181 static const int kDescriptorIndexBitCount = 10;
182 // The maximum number of descriptors we want in a descriptor array (should
184 static const int kMaxNumberOfDescriptors =
185 (1 << kDescriptorIndexBitCount) - 2;
186 static const int kInvalidEnumCacheSentinel =
187 (1 << kDescriptorIndexBitCount) - 1;
190 // PropertyDetails captures type and attributes for a property.
191 // They are used both in property dictionaries and instance descriptors.
192 class PropertyDetails BASE_EMBEDDED {
194 PropertyDetails(PropertyAttributes attributes,
197 value_ = TypeField::encode(type)
198 | AttributesField::encode(attributes)
199 | DictionaryStorageField::encode(index);
201 DCHECK(type == this->type());
202 DCHECK(attributes == this->attributes());
205 PropertyDetails(PropertyAttributes attributes,
207 Representation representation,
208 int field_index = 0) {
209 value_ = TypeField::encode(type)
210 | AttributesField::encode(attributes)
211 | RepresentationField::encode(EncodeRepresentation(representation))
212 | FieldIndexField::encode(field_index);
215 PropertyDetails(PropertyAttributes attributes, PropertyKind kind,
216 PropertyLocation location, Representation representation,
217 int field_index = 0) {
218 value_ = KindField::encode(kind) | LocationField::encode(location) |
219 AttributesField::encode(attributes) |
220 RepresentationField::encode(EncodeRepresentation(representation)) |
221 FieldIndexField::encode(field_index);
224 int pointer() const { return DescriptorPointer::decode(value_); }
226 PropertyDetails set_pointer(int i) { return PropertyDetails(value_, i); }
228 PropertyDetails CopyWithRepresentation(Representation representation) const {
229 return PropertyDetails(value_, representation);
231 PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) {
233 static_cast<PropertyAttributes>(attributes() | new_attributes);
234 return PropertyDetails(value_, new_attributes);
237 // Conversion for storing details as Object*.
238 explicit inline PropertyDetails(Smi* smi);
239 inline Smi* AsSmi() const;
241 static uint8_t EncodeRepresentation(Representation representation) {
242 return representation.kind();
245 static Representation DecodeRepresentation(uint32_t bits) {
246 return Representation::FromKind(static_cast<Representation::Kind>(bits));
249 PropertyKind kind() const { return KindField::decode(value_); }
250 PropertyLocation location() const { return LocationField::decode(value_); }
252 PropertyType type() const { return TypeField::decode(value_); }
254 PropertyAttributes attributes() const {
255 return AttributesField::decode(value_);
258 int dictionary_index() const {
259 return DictionaryStorageField::decode(value_);
262 Representation representation() const {
263 return DecodeRepresentation(RepresentationField::decode(value_));
266 int field_index() const { return FieldIndexField::decode(value_); }
268 inline int field_width_in_words() const;
270 inline PropertyDetails AsDeleted() const;
272 static bool IsValidIndex(int index) {
273 return DictionaryStorageField::is_valid(index);
276 bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
277 bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; }
278 bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
279 bool IsDeleted() const { return DeletedField::decode(value_) != 0; }
281 // Bit fields in value_ (type, shift, size). Must be public so the
282 // constants can be embedded in generated code.
283 class KindField : public BitField<PropertyKind, 0, 1> {};
284 class LocationField : public BitField<PropertyLocation, 1, 1> {};
285 class AttributesField : public BitField<PropertyAttributes, 2, 3> {};
287 // Bit fields for normalized objects.
288 class DeletedField : public BitField<uint32_t, 5, 1> {};
289 class DictionaryStorageField : public BitField<uint32_t, 6, 24> {};
291 // Bit fields for fast objects.
292 class RepresentationField : public BitField<uint32_t, 5, 4> {};
293 class DescriptorPointer
294 : public BitField<uint32_t, 9, kDescriptorIndexBitCount> {}; // NOLINT
295 class FieldIndexField
296 : public BitField<uint32_t, 9 + kDescriptorIndexBitCount,
297 kDescriptorIndexBitCount> {}; // NOLINT
299 // NOTE: TypeField overlaps with KindField and LocationField.
300 class TypeField : public BitField<PropertyType, 0, 2> {};
301 STATIC_ASSERT(KindField::kNext == LocationField::kShift);
302 STATIC_ASSERT(TypeField::kShift == KindField::kShift);
303 STATIC_ASSERT(TypeField::kNext == LocationField::kNext);
305 // All bits for both fast and slow objects must fit in a smi.
306 STATIC_ASSERT(DictionaryStorageField::kNext <= 31);
307 STATIC_ASSERT(FieldIndexField::kNext <= 31);
309 static const int kInitialIndex = 1;
312 // For our gdb macros, we should perhaps change these in the future.
313 void Print(bool dictionary_mode);
317 PropertyDetails(int value, int pointer) {
318 value_ = DescriptorPointer::update(value, pointer);
320 PropertyDetails(int value, Representation representation) {
321 value_ = RepresentationField::update(
322 value, EncodeRepresentation(representation));
324 PropertyDetails(int value, PropertyAttributes attributes) {
325 value_ = AttributesField::update(value, attributes);
332 std::ostream& operator<<(std::ostream& os,
333 const PropertyAttributes& attributes);
334 std::ostream& operator<<(std::ostream& os, const PropertyDetails& details);
335 } } // namespace v8::internal
337 #endif // V8_PROPERTY_DETAILS_H_