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 6720 : Representation() : kind_(kNone) { }
98 :
99 : static Representation None() { return Representation(kNone); }
100 : static Representation Tagged() { return Representation(kTagged); }
101 : static Representation Smi() { return Representation(kSmi); }
102 : static Representation Double() { return Representation(kDouble); }
103 : 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 2327729 : 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 CanBeInPlaceChangedTo(const Representation& other) const {
120 276249 : if (IsNone()) return true;
121 98564 : if (!FLAG_modify_field_representation_inplace) return false;
122 192144 : return (IsSmi() || IsHeapObject()) && other.IsTagged();
123 : }
124 :
125 : bool is_more_general_than(const Representation& other) const {
126 901144 : if (IsHeapObject()) return other.IsNone();
127 344681 : return kind_ > other.kind_;
128 : }
129 :
130 : bool fits_into(const Representation& other) const {
131 871251 : return other.is_more_general_than(*this) || other.Equals(*this);
132 : }
133 :
134 336725 : Representation generalize(Representation other) {
135 336725 : if (other.fits_into(*this)) return *this;
136 41461 : if (other.is_more_general_than(*this)) return other;
137 : return Representation::Tagged();
138 : }
139 :
140 : int size() const {
141 : DCHECK(!IsNone());
142 : if (IsDouble()) return kDoubleSize;
143 : DCHECK(IsTagged() || IsSmi() || IsHeapObject());
144 : return kTaggedSize;
145 : }
146 :
147 193978135 : Kind kind() const { return static_cast<Kind>(kind_); }
148 842642 : bool IsNone() const { return kind_ == kNone; }
149 93580 : bool IsTagged() const { return kind_ == kTagged; }
150 : bool IsSmi() const { return kind_ == kSmi; }
151 : bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); }
152 40671974 : bool IsDouble() const { return kind_ == kDouble; }
153 466478 : bool IsHeapObject() const { return kind_ == kHeapObject; }
154 :
155 32105 : const char* Mnemonic() const {
156 32105 : switch (kind_) {
157 : case kNone:
158 : return "v";
159 : case kTagged:
160 5853 : return "t";
161 : case kSmi:
162 5735 : return "s";
163 : case kDouble:
164 476 : return "d";
165 : case kHeapObject:
166 20041 : return "h";
167 : }
168 0 : UNREACHABLE();
169 : }
170 :
171 : private:
172 622529319 : explicit Representation(Kind k) : kind_(k) { }
173 :
174 : // Make sure kind fits in int8.
175 : STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte));
176 :
177 : int8_t kind_;
178 : };
179 :
180 :
181 : static const int kDescriptorIndexBitCount = 10;
182 : static const int kFirstInobjectPropertyOffsetBitCount = 7;
183 : // The maximum number of descriptors we want in a descriptor array. It should
184 : // fit in a page and also the following should hold:
185 : // kMaxNumberOfDescriptors + kFieldsAdded <= PropertyArray::kMaxLength.
186 : static const int kMaxNumberOfDescriptors = (1 << kDescriptorIndexBitCount) - 4;
187 : static const int kInvalidEnumCacheSentinel =
188 : (1 << kDescriptorIndexBitCount) - 1;
189 :
190 : enum class PropertyCellType {
191 : // Meaningful when a property cell does not contain the hole.
192 : kUndefined, // The PREMONOMORPHIC of property cells.
193 : kConstant, // Cell has been assigned only once.
194 : kConstantType, // Cell has been assigned only one type.
195 : kMutable, // Cell will no longer be tracked as constant.
196 :
197 : // Meaningful when a property cell contains the hole.
198 : kUninitialized = kUndefined, // Cell has never been initialized.
199 : kInvalidated = kConstant, // Cell has been deleted, invalidated or never
200 : // existed.
201 :
202 : // For dictionaries not holding cells.
203 : kNoCell = kMutable,
204 : };
205 :
206 : enum class PropertyCellConstantType {
207 : kSmi,
208 : kStableMap,
209 : };
210 :
211 :
212 : // PropertyDetails captures type and attributes for a property.
213 : // They are used both in property dictionaries and instance descriptors.
214 : class PropertyDetails {
215 : public:
216 : // Property details for dictionary mode properties/elements.
217 : PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
218 : PropertyCellType cell_type, int dictionary_index = 0) {
219 2036265 : value_ = KindField::encode(kind) | LocationField::encode(kField) |
220 8382717 : AttributesField::encode(attributes) |
221 16342774 : DictionaryStorageField::encode(dictionary_index) |
222 11902142 : PropertyCellTypeField::encode(cell_type);
223 : }
224 :
225 : // Property details for fast mode properties.
226 : PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
227 : PropertyLocation location, PropertyConstness constness,
228 : Representation representation, int field_index = 0) {
229 625115 : value_ = KindField::encode(kind) | AttributesField::encode(attributes) |
230 21332413 : LocationField::encode(location) |
231 21345909 : ConstnessField::encode(constness) |
232 19102212 : RepresentationField::encode(EncodeRepresentation(representation)) |
233 21246055 : FieldIndexField::encode(field_index);
234 : }
235 :
236 : static PropertyDetails Empty(
237 : PropertyCellType cell_type = PropertyCellType::kNoCell) {
238 : return PropertyDetails(kData, NONE, cell_type);
239 : }
240 :
241 3299635867 : int pointer() const { return DescriptorPointer::decode(value_); }
242 :
243 : PropertyDetails set_pointer(int i) const {
244 882096062 : return PropertyDetails(value_, i);
245 : }
246 :
247 : PropertyDetails set_cell_type(PropertyCellType type) const {
248 8327718 : PropertyDetails details = *this;
249 : details.value_ = PropertyCellTypeField::update(details.value_, type);
250 : return details;
251 : }
252 :
253 : PropertyDetails set_index(int index) const {
254 0 : PropertyDetails details = *this;
255 17523161 : details.value_ = DictionaryStorageField::update(details.value_, index);
256 : return details;
257 : }
258 :
259 : PropertyDetails CopyWithRepresentation(Representation representation) const {
260 : return PropertyDetails(value_, representation);
261 : }
262 : PropertyDetails CopyWithConstness(PropertyConstness constness) const {
263 : return PropertyDetails(value_, constness);
264 : }
265 : PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) const {
266 : new_attributes =
267 615499 : static_cast<PropertyAttributes>(attributes() | new_attributes);
268 : return PropertyDetails(value_, new_attributes);
269 : }
270 :
271 : // Conversion for storing details as Object.
272 : explicit inline PropertyDetails(Smi smi);
273 : inline Smi AsSmi() const;
274 :
275 : static uint8_t EncodeRepresentation(Representation representation) {
276 : return representation.kind();
277 : }
278 :
279 : static Representation DecodeRepresentation(uint32_t bits) {
280 : return Representation::FromKind(static_cast<Representation::Kind>(bits));
281 : }
282 :
283 37971136 : PropertyKind kind() const { return KindField::decode(value_); }
284 284550933 : PropertyLocation location() const { return LocationField::decode(value_); }
285 255331 : PropertyConstness constness() const { return ConstnessField::decode(value_); }
286 :
287 : PropertyAttributes attributes() const {
288 29841625 : return AttributesField::decode(value_);
289 : }
290 :
291 : bool HasKindAndAttributes(PropertyKind kind, PropertyAttributes attributes) {
292 5683109 : return (value_ & (KindField::kMask | AttributesField::kMask)) ==
293 5683109 : (KindField::encode(kind) | AttributesField::encode(attributes));
294 : }
295 :
296 : int dictionary_index() const {
297 368007869 : return DictionaryStorageField::decode(value_);
298 : }
299 :
300 236632 : Representation representation() const {
301 115877886 : return DecodeRepresentation(RepresentationField::decode(value_));
302 : }
303 :
304 957390085 : int field_index() const { return FieldIndexField::decode(value_); }
305 :
306 : inline int field_width_in_words() const;
307 :
308 : static bool IsValidIndex(int index) {
309 12889657 : return DictionaryStorageField::is_valid(index);
310 : }
311 :
312 47769248 : bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
313 9393633 : bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; }
314 8845758 : bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
315 : bool IsEnumerable() const { return !IsDontEnum(); }
316 : PropertyCellType cell_type() const {
317 13182718 : return PropertyCellTypeField::decode(value_);
318 : }
319 :
320 : // Bit fields in value_ (type, shift, size). Must be public so the
321 : // constants can be embedded in generated code.
322 : class KindField : public BitField<PropertyKind, 0, 1> {};
323 : class LocationField : public BitField<PropertyLocation, KindField::kNext, 1> {
324 : };
325 : class ConstnessField
326 : : public BitField<PropertyConstness, LocationField::kNext, 1> {};
327 : class AttributesField
328 : : public BitField<PropertyAttributes, ConstnessField::kNext, 3> {};
329 : static const int kAttributesReadOnlyMask =
330 : (READ_ONLY << AttributesField::kShift);
331 : static const int kAttributesDontDeleteMask =
332 : (DONT_DELETE << AttributesField::kShift);
333 : static const int kAttributesDontEnumMask =
334 : (DONT_ENUM << AttributesField::kShift);
335 :
336 : // Bit fields for normalized objects.
337 : class PropertyCellTypeField
338 : : public BitField<PropertyCellType, AttributesField::kNext, 2> {};
339 : class DictionaryStorageField
340 : : public BitField<uint32_t, PropertyCellTypeField::kNext, 23> {};
341 :
342 : // Bit fields for fast objects.
343 : class RepresentationField
344 : : public BitField<uint32_t, AttributesField::kNext, 3> {};
345 : class DescriptorPointer
346 : : public BitField<uint32_t, RepresentationField::kNext,
347 : kDescriptorIndexBitCount> {}; // NOLINT
348 : class FieldIndexField : public BitField<uint32_t, DescriptorPointer::kNext,
349 : kDescriptorIndexBitCount> {
350 : }; // NOLINT
351 :
352 : // All bits for both fast and slow objects must fit in a smi.
353 : STATIC_ASSERT(DictionaryStorageField::kNext <= 31);
354 : STATIC_ASSERT(FieldIndexField::kNext <= 31);
355 :
356 : static const int kInitialIndex = 1;
357 :
358 : #ifdef OBJECT_PRINT
359 : // For our gdb macros, we should perhaps change these in the future.
360 : void Print(bool dictionary_mode);
361 : #endif
362 :
363 : enum PrintMode {
364 : kPrintAttributes = 1 << 0,
365 : kPrintFieldIndex = 1 << 1,
366 : kPrintRepresentation = 1 << 2,
367 : kPrintPointer = 1 << 3,
368 :
369 : kForProperties = kPrintFieldIndex,
370 : kForTransitions = kPrintAttributes,
371 : kPrintFull = -1,
372 : };
373 : void PrintAsSlowTo(std::ostream& out);
374 : void PrintAsFastTo(std::ostream& out, PrintMode mode = kPrintFull);
375 :
376 : private:
377 : PropertyDetails(int value, int pointer) {
378 881827661 : value_ = DescriptorPointer::update(value, pointer);
379 : }
380 : PropertyDetails(int value, Representation representation) {
381 : value_ = RepresentationField::update(
382 : value, EncodeRepresentation(representation));
383 : }
384 : PropertyDetails(int value, PropertyConstness constness) {
385 : value_ = ConstnessField::update(value, constness);
386 : }
387 : PropertyDetails(int value, PropertyAttributes attributes) {
388 : value_ = AttributesField::update(value, attributes);
389 : }
390 :
391 : uint32_t value_;
392 : };
393 :
394 : // kField location is more general than kDescriptor, kDescriptor generalizes
395 : // only to itself.
396 : inline bool IsGeneralizableTo(PropertyLocation a, PropertyLocation b) {
397 508276 : return b == kField || a == kDescriptor;
398 : }
399 :
400 : // PropertyConstness::kMutable constness is more general than
401 : // VariableMode::kConst, VariableMode::kConst generalizes only to itself.
402 : inline bool IsGeneralizableTo(PropertyConstness a, PropertyConstness b) {
403 7987114 : return b == PropertyConstness::kMutable || a == PropertyConstness::kConst;
404 : }
405 :
406 : inline PropertyConstness GeneralizeConstness(PropertyConstness a,
407 : PropertyConstness b) {
408 602367 : return a == PropertyConstness::kMutable ? PropertyConstness::kMutable : b;
409 : }
410 :
411 : V8_EXPORT_PRIVATE std::ostream& operator<<(
412 : std::ostream& os, const PropertyAttributes& attributes);
413 : } // namespace internal
414 : } // namespace v8
415 :
416 : #endif // V8_PROPERTY_DETAILS_H_
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