Line data Source code
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.
4 :
5 : #ifndef V8_PROPERTY_DETAILS_H_
6 : #define V8_PROPERTY_DETAILS_H_
7 :
8 : #include "include/v8.h"
9 : #include "src/allocation.h"
10 : // TODO(ishell): remove once FLAG_track_constant_fields is removed.
11 : #include "src/flags.h"
12 : #include "src/utils.h"
13 :
14 : namespace v8 {
15 : namespace internal {
16 :
17 : // ES6 6.1.7.1
18 : enum PropertyAttributes {
19 : NONE = ::v8::None,
20 : READ_ONLY = ::v8::ReadOnly,
21 : DONT_ENUM = ::v8::DontEnum,
22 : DONT_DELETE = ::v8::DontDelete,
23 :
24 : ALL_ATTRIBUTES_MASK = READ_ONLY | DONT_ENUM | DONT_DELETE,
25 :
26 : SEALED = DONT_DELETE,
27 : FROZEN = SEALED | READ_ONLY,
28 :
29 : ABSENT = 64, // Used in runtime to indicate a property is absent.
30 : // ABSENT can never be stored in or returned from a descriptor's attributes
31 : // bitfield. It is only used as a return value meaning the attributes of
32 : // a non-existent property.
33 : };
34 :
35 : enum PropertyFilter {
36 : ALL_PROPERTIES = 0,
37 : ONLY_WRITABLE = 1,
38 : ONLY_ENUMERABLE = 2,
39 : ONLY_CONFIGURABLE = 4,
40 : SKIP_STRINGS = 8,
41 : SKIP_SYMBOLS = 16,
42 : ONLY_ALL_CAN_READ = 32,
43 : PRIVATE_NAMES_ONLY = 64,
44 : ENUMERABLE_STRINGS = ONLY_ENUMERABLE | SKIP_SYMBOLS,
45 : };
46 : // Enable fast comparisons of PropertyAttributes against PropertyFilters.
47 : STATIC_ASSERT(ALL_PROPERTIES == static_cast<PropertyFilter>(NONE));
48 : STATIC_ASSERT(ONLY_WRITABLE == static_cast<PropertyFilter>(READ_ONLY));
49 : STATIC_ASSERT(ONLY_ENUMERABLE == static_cast<PropertyFilter>(DONT_ENUM));
50 : STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>(DONT_DELETE));
51 : STATIC_ASSERT(((SKIP_STRINGS | SKIP_SYMBOLS | ONLY_ALL_CAN_READ) &
52 : ALL_ATTRIBUTES_MASK) == 0);
53 : STATIC_ASSERT(ALL_PROPERTIES ==
54 : static_cast<PropertyFilter>(v8::PropertyFilter::ALL_PROPERTIES));
55 : STATIC_ASSERT(ONLY_WRITABLE ==
56 : static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_WRITABLE));
57 : STATIC_ASSERT(ONLY_ENUMERABLE ==
58 : static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_ENUMERABLE));
59 : STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>(
60 : v8::PropertyFilter::ONLY_CONFIGURABLE));
61 : STATIC_ASSERT(SKIP_STRINGS ==
62 : static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_STRINGS));
63 : STATIC_ASSERT(SKIP_SYMBOLS ==
64 : static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_SYMBOLS));
65 :
66 : class Smi;
67 : class TypeInfo;
68 :
69 : // Order of kinds is significant.
70 : // Must fit in the BitField PropertyDetails::KindField.
71 : enum PropertyKind { kData = 0, kAccessor = 1 };
72 :
73 : // Order of modes is significant.
74 : // Must fit in the BitField PropertyDetails::LocationField.
75 : enum PropertyLocation { kField = 0, kDescriptor = 1 };
76 :
77 : // Order of modes is significant.
78 : // Must fit in the BitField PropertyDetails::ConstnessField.
79 : enum class PropertyConstness { kMutable = 0, kConst = 1 };
80 :
81 : // TODO(ishell): remove once constant field tracking is done.
82 : const PropertyConstness kDefaultFieldConstness =
83 : FLAG_track_constant_fields ? PropertyConstness::kConst
84 : : PropertyConstness::kMutable;
85 :
86 : class Representation {
87 : public:
88 : enum Kind {
89 : kNone,
90 : kSmi,
91 : kDouble,
92 : kHeapObject,
93 : kTagged,
94 : kNumRepresentations
95 : };
96 :
97 6400 : Representation() : kind_(kNone) { }
98 :
99 : static Representation None() { return Representation(kNone); }
100 168 : static Representation Tagged() { return Representation(kTagged); }
101 168 : static Representation Smi() { return Representation(kSmi); }
102 168 : static Representation Double() { return Representation(kDouble); }
103 168 : static Representation HeapObject() { return Representation(kHeapObject); }
104 :
105 : static Representation FromKind(Kind kind) { return Representation(kind); }
106 :
107 : bool Equals(const Representation& other) const {
108 669202 : return kind_ == other.kind_;
109 : }
110 :
111 : bool IsCompatibleForLoad(const Representation& other) const {
112 : return IsDouble() == other.IsDouble();
113 : }
114 :
115 : bool IsCompatibleForStore(const Representation& other) const {
116 : return Equals(other);
117 : }
118 :
119 : bool is_more_general_than(const Representation& other) const {
120 939496 : if (IsHeapObject()) return other.IsNone();
121 370674 : return kind_ > other.kind_;
122 : }
123 :
124 : bool fits_into(const Representation& other) const {
125 910982 : return other.is_more_general_than(*this) || other.Equals(*this);
126 : }
127 :
128 350796 : Representation generalize(Representation other) {
129 350796 : if (other.fits_into(*this)) return *this;
130 40218 : if (other.is_more_general_than(*this)) return other;
131 : return Representation::Tagged();
132 : }
133 :
134 : int size() const {
135 : DCHECK(!IsNone());
136 : if (IsDouble()) return kDoubleSize;
137 : DCHECK(IsTagged() || IsSmi() || IsHeapObject());
138 : return kTaggedSize;
139 : }
140 :
141 224656132 : Kind kind() const { return static_cast<Kind>(kind_); }
142 869690 : bool IsNone() const { return kind_ == kNone; }
143 : bool IsTagged() const { return kind_ == kTagged; }
144 1344 : bool IsSmi() const { return kind_ == kSmi; }
145 : bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); }
146 40250986 : bool IsDouble() const { return kind_ == kDouble; }
147 479811 : bool IsHeapObject() const { return kind_ == kHeapObject; }
148 :
149 32201 : const char* Mnemonic() const {
150 32201 : switch (kind_) {
151 : case kNone:
152 : return "v";
153 : case kTagged:
154 5869 : return "t";
155 : case kSmi:
156 5783 : return "s";
157 : case kDouble:
158 508 : return "d";
159 : case kHeapObject:
160 20041 : return "h";
161 : }
162 0 : UNREACHABLE();
163 : }
164 :
165 : private:
166 577204017 : explicit Representation(Kind k) : kind_(k) { }
167 :
168 : // Make sure kind fits in int8.
169 : STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte));
170 :
171 : int8_t kind_;
172 : };
173 :
174 :
175 : static const int kDescriptorIndexBitCount = 10;
176 : static const int kFirstInobjectPropertyOffsetBitCount = 7;
177 : // The maximum number of descriptors we want in a descriptor array. It should
178 : // fit in a page and also the following should hold:
179 : // kMaxNumberOfDescriptors + kFieldsAdded <= PropertyArray::kMaxLength.
180 : static const int kMaxNumberOfDescriptors = (1 << kDescriptorIndexBitCount) - 4;
181 : static const int kInvalidEnumCacheSentinel =
182 : (1 << kDescriptorIndexBitCount) - 1;
183 :
184 : enum class PropertyCellType {
185 : // Meaningful when a property cell does not contain the hole.
186 : kUndefined, // The PREMONOMORPHIC of property cells.
187 : kConstant, // Cell has been assigned only once.
188 : kConstantType, // Cell has been assigned only one type.
189 : kMutable, // Cell will no longer be tracked as constant.
190 :
191 : // Meaningful when a property cell contains the hole.
192 : kUninitialized = kUndefined, // Cell has never been initialized.
193 : kInvalidated = kConstant, // Cell has been deleted, invalidated or never
194 : // existed.
195 :
196 : // For dictionaries not holding cells.
197 : kNoCell = kMutable,
198 : };
199 :
200 : enum class PropertyCellConstantType {
201 : kSmi,
202 : kStableMap,
203 : };
204 :
205 :
206 : // PropertyDetails captures type and attributes for a property.
207 : // They are used both in property dictionaries and instance descriptors.
208 : class PropertyDetails {
209 : public:
210 : // Property details for dictionary mode properties/elements.
211 1008 : PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
212 : PropertyCellType cell_type, int dictionary_index = 0) {
213 2027921 : value_ = KindField::encode(kind) | LocationField::encode(kField) |
214 8278986 : AttributesField::encode(attributes) |
215 16080409 : DictionaryStorageField::encode(dictionary_index) |
216 11787584 : PropertyCellTypeField::encode(cell_type);
217 1008 : }
218 :
219 : // Property details for fast mode properties.
220 : PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
221 : PropertyLocation location, PropertyConstness constness,
222 : Representation representation, int field_index = 0) {
223 677806 : value_ = KindField::encode(kind) | AttributesField::encode(attributes) |
224 21099006 : LocationField::encode(location) |
225 21118520 : ConstnessField::encode(constness) |
226 18867615 : RepresentationField::encode(EncodeRepresentation(representation)) |
227 20988732 : FieldIndexField::encode(field_index);
228 : }
229 :
230 : static PropertyDetails Empty(
231 : PropertyCellType cell_type = PropertyCellType::kNoCell) {
232 : return PropertyDetails(kData, NONE, cell_type);
233 : }
234 :
235 3185401470 : int pointer() const { return DescriptorPointer::decode(value_); }
236 :
237 : PropertyDetails set_pointer(int i) const {
238 851593708 : return PropertyDetails(value_, i);
239 : }
240 :
241 : PropertyDetails set_cell_type(PropertyCellType type) const {
242 8222042 : PropertyDetails details = *this;
243 : details.value_ = PropertyCellTypeField::update(details.value_, type);
244 : return details;
245 : }
246 :
247 : PropertyDetails set_index(int index) const {
248 0 : PropertyDetails details = *this;
249 17294609 : details.value_ = DictionaryStorageField::update(details.value_, index);
250 : return details;
251 : }
252 :
253 : PropertyDetails CopyWithRepresentation(Representation representation) const {
254 : return PropertyDetails(value_, representation);
255 : }
256 : PropertyDetails CopyWithConstness(PropertyConstness constness) const {
257 : return PropertyDetails(value_, constness);
258 : }
259 : PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) const {
260 : new_attributes =
261 253489 : static_cast<PropertyAttributes>(attributes() | new_attributes);
262 : return PropertyDetails(value_, new_attributes);
263 : }
264 :
265 : // Conversion for storing details as Object.
266 : explicit inline PropertyDetails(Smi smi);
267 : inline Smi AsSmi() const;
268 :
269 : static uint8_t EncodeRepresentation(Representation representation) {
270 : return representation.kind();
271 : }
272 :
273 : static Representation DecodeRepresentation(uint32_t bits) {
274 : return Representation::FromKind(static_cast<Representation::Kind>(bits));
275 : }
276 :
277 36906006 : PropertyKind kind() const { return KindField::decode(value_); }
278 283003585 : PropertyLocation location() const { return LocationField::decode(value_); }
279 249058 : PropertyConstness constness() const { return ConstnessField::decode(value_); }
280 :
281 : PropertyAttributes attributes() const {
282 26736819 : return AttributesField::decode(value_);
283 : }
284 :
285 : bool HasKindAndAttributes(PropertyKind kind, PropertyAttributes attributes) {
286 5702688 : return (value_ & (KindField::kMask | AttributesField::kMask)) ==
287 5702688 : (KindField::encode(kind) | AttributesField::encode(attributes));
288 : }
289 :
290 : int dictionary_index() const {
291 373112239 : return DictionaryStorageField::decode(value_);
292 : }
293 :
294 236717 : Representation representation() const {
295 130320704 : return DecodeRepresentation(RepresentationField::decode(value_));
296 : }
297 :
298 957728754 : int field_index() const { return FieldIndexField::decode(value_); }
299 :
300 : inline int field_width_in_words() const;
301 :
302 : static bool IsValidIndex(int index) {
303 12698685 : return DictionaryStorageField::is_valid(index);
304 : }
305 :
306 46582601 : bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
307 9392287 : bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; }
308 8846782 : bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
309 : bool IsEnumerable() const { return !IsDontEnum(); }
310 : PropertyCellType cell_type() const {
311 13037913 : return PropertyCellTypeField::decode(value_);
312 : }
313 :
314 : // Bit fields in value_ (type, shift, size). Must be public so the
315 : // constants can be embedded in generated code.
316 : class KindField : public BitField<PropertyKind, 0, 1> {};
317 : class LocationField : public BitField<PropertyLocation, KindField::kNext, 1> {
318 : };
319 : class ConstnessField
320 : : public BitField<PropertyConstness, LocationField::kNext, 1> {};
321 : class AttributesField
322 : : public BitField<PropertyAttributes, ConstnessField::kNext, 3> {};
323 : static const int kAttributesReadOnlyMask =
324 : (READ_ONLY << AttributesField::kShift);
325 : static const int kAttributesDontDeleteMask =
326 : (DONT_DELETE << AttributesField::kShift);
327 : static const int kAttributesDontEnumMask =
328 : (DONT_ENUM << AttributesField::kShift);
329 :
330 : // Bit fields for normalized objects.
331 : class PropertyCellTypeField
332 : : public BitField<PropertyCellType, AttributesField::kNext, 2> {};
333 : class DictionaryStorageField
334 : : public BitField<uint32_t, PropertyCellTypeField::kNext, 23> {};
335 :
336 : // Bit fields for fast objects.
337 : class RepresentationField
338 : : public BitField<uint32_t, AttributesField::kNext, 3> {};
339 : class DescriptorPointer
340 : : public BitField<uint32_t, RepresentationField::kNext,
341 : kDescriptorIndexBitCount> {}; // NOLINT
342 : class FieldIndexField : public BitField<uint32_t, DescriptorPointer::kNext,
343 : kDescriptorIndexBitCount> {
344 : }; // NOLINT
345 :
346 : // All bits for both fast and slow objects must fit in a smi.
347 : STATIC_ASSERT(DictionaryStorageField::kNext <= 31);
348 : STATIC_ASSERT(FieldIndexField::kNext <= 31);
349 :
350 : static const int kInitialIndex = 1;
351 :
352 : #ifdef OBJECT_PRINT
353 : // For our gdb macros, we should perhaps change these in the future.
354 : void Print(bool dictionary_mode);
355 : #endif
356 :
357 : enum PrintMode {
358 : kPrintAttributes = 1 << 0,
359 : kPrintFieldIndex = 1 << 1,
360 : kPrintRepresentation = 1 << 2,
361 : kPrintPointer = 1 << 3,
362 :
363 : kForProperties = kPrintFieldIndex,
364 : kForTransitions = kPrintAttributes,
365 : kPrintFull = -1,
366 : };
367 : void PrintAsSlowTo(std::ostream& out);
368 : void PrintAsFastTo(std::ostream& out, PrintMode mode = kPrintFull);
369 :
370 : private:
371 : PropertyDetails(int value, int pointer) {
372 851322150 : value_ = DescriptorPointer::update(value, pointer);
373 : }
374 : PropertyDetails(int value, Representation representation) {
375 : value_ = RepresentationField::update(
376 : value, EncodeRepresentation(representation));
377 : }
378 : PropertyDetails(int value, PropertyConstness constness) {
379 : value_ = ConstnessField::update(value, constness);
380 : }
381 : PropertyDetails(int value, PropertyAttributes attributes) {
382 : value_ = AttributesField::update(value, attributes);
383 : }
384 :
385 : uint32_t value_;
386 : };
387 :
388 : // kField location is more general than kDescriptor, kDescriptor generalizes
389 : // only to itself.
390 : inline bool IsGeneralizableTo(PropertyLocation a, PropertyLocation b) {
391 532930 : return b == kField || a == kDescriptor;
392 : }
393 :
394 : // PropertyConstness::kMutable constness is more general than
395 : // VariableMode::kConst, VariableMode::kConst generalizes only to itself.
396 : inline bool IsGeneralizableTo(PropertyConstness a, PropertyConstness b) {
397 7995710 : return b == PropertyConstness::kMutable || a == PropertyConstness::kConst;
398 : }
399 :
400 : inline PropertyConstness GeneralizeConstness(PropertyConstness a,
401 : PropertyConstness b) {
402 605391 : return a == PropertyConstness::kMutable ? PropertyConstness::kMutable : b;
403 : }
404 :
405 : std::ostream& operator<<(std::ostream& os,
406 : const PropertyAttributes& attributes);
407 : } // namespace internal
408 : } // namespace v8
409 :
410 : #endif // V8_PROPERTY_DETAILS_H_
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