1/*
2 * Copyright (C) 2008-2019 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "Structure.h"
28
29#include "BuiltinNames.h"
30#include "CodeBlock.h"
31#include "DumpContext.h"
32#include "JSCInlines.h"
33#include "JSObject.h"
34#include "JSPropertyNameEnumerator.h"
35#include "Lookup.h"
36#include "PropertyMapHashTable.h"
37#include "PropertyNameArray.h"
38#include "StructureChain.h"
39#include "StructureRareDataInlines.h"
40#include "WeakGCMapInlines.h"
41#include <wtf/CommaPrinter.h>
42#include <wtf/NeverDestroyed.h>
43#include <wtf/ProcessID.h>
44#include <wtf/RefPtr.h>
45#include <wtf/Threading.h>
46
47#define DUMP_STRUCTURE_ID_STATISTICS 0
48
49namespace JSC {
50
51#if DUMP_STRUCTURE_ID_STATISTICS
52static HashSet<Structure*>& liveStructureSet = *(new HashSet<Structure*>);
53#endif
54
55class SingleSlotTransitionWeakOwner final : public WeakHandleOwner {
56 void finalize(Handle<Unknown>, void* context) override
57 {
58 StructureTransitionTable* table = reinterpret_cast<StructureTransitionTable*>(context);
59 ASSERT(table->isUsingSingleSlot());
60 WeakSet::deallocate(table->weakImpl());
61 table->m_data = StructureTransitionTable::UsingSingleSlotFlag;
62 }
63};
64
65static SingleSlotTransitionWeakOwner& singleSlotTransitionWeakOwner()
66{
67 static NeverDestroyed<SingleSlotTransitionWeakOwner> owner;
68 return owner;
69}
70
71inline Structure* StructureTransitionTable::singleTransition() const
72{
73 ASSERT(isUsingSingleSlot());
74 if (WeakImpl* impl = this->weakImpl()) {
75 if (impl->state() == WeakImpl::Live)
76 return jsCast<Structure*>(impl->jsValue().asCell());
77 }
78 return nullptr;
79}
80
81inline void StructureTransitionTable::setSingleTransition(Structure* structure)
82{
83 ASSERT(isUsingSingleSlot());
84 if (WeakImpl* impl = this->weakImpl())
85 WeakSet::deallocate(impl);
86 WeakImpl* impl = WeakSet::allocate(structure, &singleSlotTransitionWeakOwner(), this);
87 m_data = bitwise_cast<intptr_t>(impl) | UsingSingleSlotFlag;
88}
89
90bool StructureTransitionTable::contains(UniquedStringImpl* rep, unsigned attributes) const
91{
92 if (isUsingSingleSlot()) {
93 Structure* transition = singleTransition();
94 return transition && transition->m_nameInPrevious == rep && transition->attributesInPrevious() == attributes;
95 }
96 return map()->get(std::make_pair(rep, attributes));
97}
98
99inline Structure* StructureTransitionTable::get(UniquedStringImpl* rep, unsigned attributes) const
100{
101 if (isUsingSingleSlot()) {
102 Structure* transition = singleTransition();
103 return (transition && transition->m_nameInPrevious == rep && transition->attributesInPrevious() == attributes) ? transition : 0;
104 }
105 return map()->get(std::make_pair(rep, attributes));
106}
107
108void StructureTransitionTable::add(VM& vm, Structure* structure)
109{
110 if (isUsingSingleSlot()) {
111 Structure* existingTransition = singleTransition();
112
113 // This handles the first transition being added.
114 if (!existingTransition) {
115 setSingleTransition(structure);
116 return;
117 }
118
119 // This handles the second transition being added
120 // (or the first transition being despecified!)
121 setMap(new TransitionMap(vm));
122 add(vm, existingTransition);
123 }
124
125 // Add the structure to the map.
126
127 // Newer versions of the STL have an std::make_pair function that takes rvalue references.
128 // When either of the parameters are bitfields, the C++ compiler will try to bind them as lvalues, which is invalid. To work around this, use unary "+" to make the parameter an rvalue.
129 // See https://bugs.webkit.org/show_bug.cgi?id=59261 for more details
130 map()->set(std::make_pair(structure->m_nameInPrevious.get(), +structure->attributesInPrevious()), structure);
131}
132
133void Structure::dumpStatistics()
134{
135#if DUMP_STRUCTURE_ID_STATISTICS
136 unsigned numberLeaf = 0;
137 unsigned numberUsingSingleSlot = 0;
138 unsigned numberSingletons = 0;
139 unsigned numberWithPropertyMaps = 0;
140 unsigned totalPropertyMapsSize = 0;
141
142 HashSet<Structure*>::const_iterator end = liveStructureSet.end();
143 for (HashSet<Structure*>::const_iterator it = liveStructureSet.begin(); it != end; ++it) {
144 Structure* structure = *it;
145
146 switch (structure->m_transitionTable.size()) {
147 case 0:
148 ++numberLeaf;
149 if (!structure->previousID())
150 ++numberSingletons;
151 break;
152
153 case 1:
154 ++numberUsingSingleSlot;
155 break;
156 }
157
158 if (PropertyTable* table = structure->propertyTableOrNull()) {
159 ++numberWithPropertyMaps;
160 totalPropertyMapsSize += table->sizeInMemory();
161 }
162 }
163
164 dataLogF("Number of live Structures: %d\n", liveStructureSet.size());
165 dataLogF("Number of Structures using the single item optimization for transition map: %d\n", numberUsingSingleSlot);
166 dataLogF("Number of Structures that are leaf nodes: %d\n", numberLeaf);
167 dataLogF("Number of Structures that singletons: %d\n", numberSingletons);
168 dataLogF("Number of Structures with PropertyMaps: %d\n", numberWithPropertyMaps);
169
170 dataLogF("Size of a single Structures: %d\n", static_cast<unsigned>(sizeof(Structure)));
171 dataLogF("Size of sum of all property maps: %d\n", totalPropertyMapsSize);
172 dataLogF("Size of average of all property maps: %f\n", static_cast<double>(totalPropertyMapsSize) / static_cast<double>(liveStructureSet.size()));
173#else
174 dataLogF("Dumping Structure statistics is not enabled.\n");
175#endif
176}
177
178Structure::Structure(VM& vm, JSGlobalObject* globalObject, JSValue prototype, const TypeInfo& typeInfo, const ClassInfo* classInfo, IndexingType indexingType, unsigned inlineCapacity)
179 : JSCell(vm, vm.structureStructure.get())
180 , m_blob(vm.heap.structureIDTable().allocateID(this), indexingType, typeInfo)
181 , m_outOfLineTypeFlags(typeInfo.outOfLineTypeFlags())
182 , m_inlineCapacity(inlineCapacity)
183 , m_bitField(0)
184 , m_globalObject(vm, this, globalObject, WriteBarrier<JSGlobalObject>::MayBeNull)
185 , m_prototype(vm, this, prototype)
186 , m_classInfo(classInfo)
187 , m_transitionWatchpointSet(IsWatched)
188 , m_offset(invalidOffset)
189 , m_propertyHash(0)
190{
191 setDictionaryKind(NoneDictionaryKind);
192 setIsPinnedPropertyTable(false);
193 setHasGetterSetterProperties(classInfo->hasStaticSetterOrReadonlyProperties());
194 setHasCustomGetterSetterProperties(false);
195 setHasReadOnlyOrGetterSetterPropertiesExcludingProto(classInfo->hasStaticSetterOrReadonlyProperties());
196 setHasUnderscoreProtoPropertyExcludingOriginalProto(false);
197 setIsQuickPropertyAccessAllowedForEnumeration(true);
198 setAttributesInPrevious(0);
199 setDidPreventExtensions(false);
200 setDidTransition(false);
201 setStaticPropertiesReified(false);
202 setTransitionWatchpointIsLikelyToBeFired(false);
203 setHasBeenDictionary(false);
204 setIsAddingPropertyForTransition(false);
205
206 ASSERT(inlineCapacity <= JSFinalObject::maxInlineCapacity());
207 ASSERT(static_cast<PropertyOffset>(inlineCapacity) < firstOutOfLineOffset);
208 ASSERT(!hasRareData());
209 ASSERT(hasReadOnlyOrGetterSetterPropertiesExcludingProto() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
210 ASSERT(hasGetterSetterProperties() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
211 ASSERT(!this->typeInfo().overridesGetCallData() || m_classInfo->methodTable.getCallData != &JSCell::getCallData);
212}
213
214const ClassInfo Structure::s_info = { "Structure", nullptr, nullptr, nullptr, CREATE_METHOD_TABLE(Structure) };
215
216Structure::Structure(VM& vm)
217 : JSCell(CreatingEarlyCell)
218 , m_inlineCapacity(0)
219 , m_bitField(0)
220 , m_prototype(vm, this, jsNull())
221 , m_classInfo(info())
222 , m_transitionWatchpointSet(IsWatched)
223 , m_offset(invalidOffset)
224 , m_propertyHash(0)
225{
226 setDictionaryKind(NoneDictionaryKind);
227 setIsPinnedPropertyTable(false);
228 setHasGetterSetterProperties(m_classInfo->hasStaticSetterOrReadonlyProperties());
229 setHasCustomGetterSetterProperties(false);
230 setHasReadOnlyOrGetterSetterPropertiesExcludingProto(m_classInfo->hasStaticSetterOrReadonlyProperties());
231 setHasUnderscoreProtoPropertyExcludingOriginalProto(false);
232 setIsQuickPropertyAccessAllowedForEnumeration(true);
233 setAttributesInPrevious(0);
234 setDidPreventExtensions(false);
235 setDidTransition(false);
236 setStaticPropertiesReified(false);
237 setTransitionWatchpointIsLikelyToBeFired(false);
238 setHasBeenDictionary(false);
239 setIsAddingPropertyForTransition(false);
240
241 TypeInfo typeInfo = TypeInfo(CellType, StructureFlags);
242 m_blob = StructureIDBlob(vm.heap.structureIDTable().allocateID(this), 0, typeInfo);
243 m_outOfLineTypeFlags = typeInfo.outOfLineTypeFlags();
244
245 ASSERT(hasReadOnlyOrGetterSetterPropertiesExcludingProto() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
246 ASSERT(hasGetterSetterProperties() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
247 ASSERT(!this->typeInfo().overridesGetCallData() || m_classInfo->methodTable.getCallData != &JSCell::getCallData);
248}
249
250Structure::Structure(VM& vm, Structure* previous, DeferredStructureTransitionWatchpointFire* deferred)
251 : JSCell(vm, vm.structureStructure.get())
252 , m_inlineCapacity(previous->m_inlineCapacity)
253 , m_bitField(0)
254 , m_prototype(vm, this, previous->m_prototype.get())
255 , m_classInfo(previous->m_classInfo)
256 , m_transitionWatchpointSet(IsWatched)
257 , m_offset(invalidOffset)
258 , m_propertyHash(previous->m_propertyHash)
259{
260 setDictionaryKind(previous->dictionaryKind());
261 setIsPinnedPropertyTable(false);
262 setHasBeenFlattenedBefore(previous->hasBeenFlattenedBefore());
263 setHasGetterSetterProperties(previous->hasGetterSetterProperties());
264 setHasCustomGetterSetterProperties(previous->hasCustomGetterSetterProperties());
265 setHasReadOnlyOrGetterSetterPropertiesExcludingProto(previous->hasReadOnlyOrGetterSetterPropertiesExcludingProto());
266 setHasUnderscoreProtoPropertyExcludingOriginalProto(previous->hasUnderscoreProtoPropertyExcludingOriginalProto());
267 setIsQuickPropertyAccessAllowedForEnumeration(previous->isQuickPropertyAccessAllowedForEnumeration());
268 setAttributesInPrevious(0);
269 setDidPreventExtensions(previous->didPreventExtensions());
270 setDidTransition(true);
271 setStaticPropertiesReified(previous->staticPropertiesReified());
272 setHasBeenDictionary(previous->hasBeenDictionary());
273 setIsAddingPropertyForTransition(false);
274
275 TypeInfo typeInfo = previous->typeInfo();
276 m_blob = StructureIDBlob(vm.heap.structureIDTable().allocateID(this), previous->indexingModeIncludingHistory(), typeInfo);
277 m_outOfLineTypeFlags = typeInfo.outOfLineTypeFlags();
278
279 ASSERT(!previous->typeInfo().structureIsImmortal());
280 setPreviousID(vm, previous);
281
282 previous->didTransitionFromThisStructure(deferred);
283
284 // Copy this bit now, in case previous was being watched.
285 setTransitionWatchpointIsLikelyToBeFired(previous->transitionWatchpointIsLikelyToBeFired());
286
287 if (previous->m_globalObject)
288 m_globalObject.set(vm, this, previous->m_globalObject.get());
289 ASSERT(hasReadOnlyOrGetterSetterPropertiesExcludingProto() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
290 ASSERT(hasGetterSetterProperties() || !m_classInfo->hasStaticSetterOrReadonlyProperties());
291 ASSERT(!this->typeInfo().overridesGetCallData() || m_classInfo->methodTable.getCallData != &JSCell::getCallData);
292}
293
294Structure::~Structure()
295{
296 if (typeInfo().structureIsImmortal())
297 return;
298 Heap::heap(this)->structureIDTable().deallocateID(this, m_blob.structureID());
299}
300
301void Structure::destroy(JSCell* cell)
302{
303 static_cast<Structure*>(cell)->Structure::~Structure();
304}
305
306Structure* Structure::create(PolyProtoTag, VM& vm, JSGlobalObject* globalObject, JSObject* prototype, const TypeInfo& typeInfo, const ClassInfo* classInfo, IndexingType indexingType, unsigned inlineCapacity)
307{
308 Structure* result = create(vm, globalObject, prototype, typeInfo, classInfo, indexingType, inlineCapacity);
309
310 unsigned oldOutOfLineCapacity = result->outOfLineCapacity();
311 result->addPropertyWithoutTransition(
312 vm, vm.propertyNames->builtinNames().polyProtoName(), static_cast<unsigned>(PropertyAttribute::DontEnum),
313 [&] (const GCSafeConcurrentJSLocker&, PropertyOffset offset, PropertyOffset newLastOffset) {
314 RELEASE_ASSERT(Structure::outOfLineCapacity(newLastOffset) == oldOutOfLineCapacity);
315 RELEASE_ASSERT(offset == knownPolyProtoOffset);
316 RELEASE_ASSERT(isInlineOffset(knownPolyProtoOffset));
317 result->m_prototype.setWithoutWriteBarrier(JSValue());
318 result->setLastOffset(newLastOffset);
319 });
320
321 return result;
322}
323
324void Structure::findStructuresAndMapForMaterialization(Vector<Structure*, 8>& structures, Structure*& structure, PropertyTable*& table)
325{
326 ASSERT(structures.isEmpty());
327 table = 0;
328
329 for (structure = this; structure; structure = structure->previousID()) {
330 structure->m_lock.lock();
331
332 table = structure->propertyTableOrNull();
333 if (table) {
334 // Leave the structure locked, so that the caller can do things to it atomically
335 // before it loses its property table.
336 return;
337 }
338
339 structures.append(structure);
340 structure->m_lock.unlock();
341 }
342
343 ASSERT(!structure);
344 ASSERT(!table);
345}
346
347PropertyTable* Structure::materializePropertyTable(VM& vm, bool setPropertyTable)
348{
349 ASSERT(structure(vm)->classInfo() == info());
350 ASSERT(!isAddingPropertyForTransition());
351
352 DeferGC deferGC(vm.heap);
353
354 Vector<Structure*, 8> structures;
355 Structure* structure;
356 PropertyTable* table;
357
358 findStructuresAndMapForMaterialization(structures, structure, table);
359
360 unsigned capacity = numberOfSlotsForLastOffset(m_offset, m_inlineCapacity);
361 if (table) {
362 table = table->copy(vm, capacity);
363 structure->m_lock.unlock();
364 } else
365 table = PropertyTable::create(vm, capacity);
366
367 // Must hold the lock on this structure, since we will be modifying this structure's
368 // property map. We don't want getConcurrently() to see the property map in a half-baked
369 // state.
370 GCSafeConcurrentJSLocker locker(m_lock, vm.heap);
371 if (setPropertyTable)
372 this->setPropertyTable(vm, table);
373
374 for (size_t i = structures.size(); i--;) {
375 structure = structures[i];
376 if (!structure->m_nameInPrevious)
377 continue;
378 PropertyMapEntry entry(structure->m_nameInPrevious.get(), structure->m_offset, structure->attributesInPrevious());
379 table->add(entry, m_offset, PropertyTable::PropertyOffsetMustNotChange);
380 }
381
382 checkOffsetConsistency(
383 table,
384 [&] () {
385 dataLog("Detected in materializePropertyTable.\n");
386 dataLog("Found structure = ", RawPointer(structure), "\n");
387 dataLog("structures = ");
388 CommaPrinter comma;
389 for (Structure* structure : structures)
390 dataLog(comma, RawPointer(structure));
391 dataLog("\n");
392 });
393
394 return table;
395}
396
397Structure* Structure::addPropertyTransitionToExistingStructureImpl(Structure* structure, UniquedStringImpl* uid, unsigned attributes, PropertyOffset& offset)
398{
399 ASSERT(!structure->isDictionary());
400 ASSERT(structure->isObject());
401
402 if (Structure* existingTransition = structure->m_transitionTable.get(uid, attributes)) {
403 validateOffset(existingTransition->m_offset, existingTransition->inlineCapacity());
404 offset = existingTransition->m_offset;
405 return existingTransition;
406 }
407
408 return 0;
409}
410
411Structure* Structure::addPropertyTransitionToExistingStructure(Structure* structure, PropertyName propertyName, unsigned attributes, PropertyOffset& offset)
412{
413 ASSERT(!isCompilationThread());
414 return addPropertyTransitionToExistingStructureImpl(structure, propertyName.uid(), attributes, offset);
415}
416
417Structure* Structure::addPropertyTransitionToExistingStructureConcurrently(Structure* structure, UniquedStringImpl* uid, unsigned attributes, PropertyOffset& offset)
418{
419 ConcurrentJSLocker locker(structure->m_lock);
420 return addPropertyTransitionToExistingStructureImpl(structure, uid, attributes, offset);
421}
422
423bool Structure::holesMustForwardToPrototype(VM& vm, JSObject* base) const
424{
425 ASSERT(base->structure(vm) == this);
426
427 if (this->mayInterceptIndexedAccesses())
428 return true;
429
430 JSValue prototype = this->storedPrototype(base);
431 if (!prototype.isObject())
432 return false;
433 JSObject* object = asObject(prototype);
434
435 while (true) {
436 Structure& structure = *object->structure(vm);
437 if (hasIndexedProperties(object->indexingType()) || structure.mayInterceptIndexedAccesses())
438 return true;
439 prototype = structure.storedPrototype(object);
440 if (!prototype.isObject())
441 return false;
442 object = asObject(prototype);
443 }
444
445 RELEASE_ASSERT_NOT_REACHED();
446 return false;
447}
448
449Structure* Structure::addPropertyTransition(VM& vm, Structure* structure, PropertyName propertyName, unsigned attributes, PropertyOffset& offset)
450{
451 Structure* newStructure = addPropertyTransitionToExistingStructure(
452 structure, propertyName, attributes, offset);
453 if (newStructure)
454 return newStructure;
455
456 return addNewPropertyTransition(
457 vm, structure, propertyName, attributes, offset, PutPropertySlot::UnknownContext);
458}
459
460Structure* Structure::addNewPropertyTransition(VM& vm, Structure* structure, PropertyName propertyName, unsigned attributes, PropertyOffset& offset, PutPropertySlot::Context context, DeferredStructureTransitionWatchpointFire* deferred)
461{
462 ASSERT(!structure->isDictionary());
463 ASSERT(structure->isObject());
464 ASSERT(!Structure::addPropertyTransitionToExistingStructure(structure, propertyName, attributes, offset));
465
466 int maxTransitionLength;
467 if (context == PutPropertySlot::PutById)
468 maxTransitionLength = s_maxTransitionLengthForNonEvalPutById;
469 else
470 maxTransitionLength = s_maxTransitionLength;
471 if (structure->transitionCount() > maxTransitionLength) {
472 ASSERT(!isCopyOnWrite(structure->indexingMode()));
473 Structure* transition = toCacheableDictionaryTransition(vm, structure, deferred);
474 ASSERT(structure != transition);
475 offset = transition->add(vm, propertyName, attributes);
476 return transition;
477 }
478
479 Structure* transition = create(vm, structure, deferred);
480
481 transition->m_cachedPrototypeChain.setMayBeNull(vm, transition, structure->m_cachedPrototypeChain.get());
482
483 // While we are adding the property, rematerializing the property table is super weird: we already
484 // have a m_nameInPrevious and attributesInPrevious but the m_offset is still wrong. If the
485 // materialization algorithm runs, it'll build a property table that already has the property but
486 // at a bogus offset. Rather than try to teach the materialization code how to create a table under
487 // those conditions, we just tell the GC not to blow the table away during this period of time.
488 // Holding the lock ensures that we either do this before the GC starts scanning the structure, in
489 // which case the GC will not blow the table away, or we do it after the GC already ran in which
490 // case all is well. If it wasn't for the lock, the GC would have TOCTOU: if could read
491 // isAddingPropertyForTransition before we set it to true, and then blow the table away after.
492 {
493 ConcurrentJSLocker locker(transition->m_lock);
494 transition->setIsAddingPropertyForTransition(true);
495 }
496
497 transition->m_blob.setIndexingModeIncludingHistory(structure->indexingModeIncludingHistory() & ~CopyOnWrite);
498 transition->m_nameInPrevious = propertyName.uid();
499 transition->setAttributesInPrevious(attributes);
500 transition->setPropertyTable(vm, structure->takePropertyTableOrCloneIfPinned(vm));
501 transition->m_offset = structure->m_offset;
502
503 offset = transition->add(vm, propertyName, attributes);
504
505 // Now that everything is fine with the new structure's bookkeeping, the GC is free to blow the
506 // table away if it wants. We can now rebuild it fine.
507 WTF::storeStoreFence();
508 transition->setIsAddingPropertyForTransition(false);
509
510 checkOffset(transition->m_offset, transition->inlineCapacity());
511 {
512 ConcurrentJSLocker locker(structure->m_lock);
513 DeferGC deferGC(vm.heap);
514 structure->m_transitionTable.add(vm, transition);
515 }
516 transition->checkOffsetConsistency();
517 structure->checkOffsetConsistency();
518 return transition;
519}
520
521Structure* Structure::removePropertyTransition(VM& vm, Structure* structure, PropertyName propertyName, PropertyOffset& offset)
522{
523 // NOTE: There are some good reasons why this goes directly to uncacheable dictionary rather than
524 // caching the removal. We can fix all of these things, but we must remember to do so, if we ever try
525 // to optimize this case.
526 //
527 // - Cached transitions usually steal the property table, and assume that this is possible because they
528 // can just rebuild the table by looking at past transitions. That code assumes that the table only
529 // grew and never shrank. To support removals, we'd have to change the property table materialization
530 // code to handle deletions. Also, we have logic to get the list of properties on a structure that
531 // lacks a property table by just looking back through the set of transitions since the last
532 // structure that had a pinned table. That logic would also have to be changed to handle cached
533 // removals.
534 //
535 ASSERT(!structure->isUncacheableDictionary());
536
537 Structure* transition = toUncacheableDictionaryTransition(vm, structure);
538
539 offset = transition->remove(propertyName);
540
541 transition->checkOffsetConsistency();
542 return transition;
543}
544
545Structure* Structure::changePrototypeTransition(VM& vm, Structure* structure, JSValue prototype, DeferredStructureTransitionWatchpointFire& deferred)
546{
547 ASSERT(prototype.isObject() || prototype.isNull());
548
549 DeferGC deferGC(vm.heap);
550 Structure* transition = create(vm, structure, &deferred);
551
552 transition->m_prototype.set(vm, transition, prototype);
553
554 PropertyTable* table = structure->copyPropertyTableForPinning(vm);
555 transition->pin(holdLock(transition->m_lock), vm, table);
556 transition->m_offset = structure->m_offset;
557
558 transition->checkOffsetConsistency();
559 return transition;
560}
561
562Structure* Structure::attributeChangeTransition(VM& vm, Structure* structure, PropertyName propertyName, unsigned attributes)
563{
564 if (!structure->isUncacheableDictionary()) {
565 Structure* transition = create(vm, structure);
566
567 PropertyTable* table = structure->copyPropertyTableForPinning(vm);
568 transition->pin(holdLock(transition->m_lock), vm, table);
569 transition->m_offset = structure->m_offset;
570
571 structure = transition;
572 }
573
574 PropertyMapEntry* entry = structure->ensurePropertyTable(vm)->get(propertyName.uid());
575 ASSERT(entry);
576 entry->attributes = attributes;
577
578 structure->checkOffsetConsistency();
579 return structure;
580}
581
582Structure* Structure::toDictionaryTransition(VM& vm, Structure* structure, DictionaryKind kind, DeferredStructureTransitionWatchpointFire* deferred)
583{
584 ASSERT(!structure->isUncacheableDictionary());
585 DeferGC deferGC(vm.heap);
586
587 Structure* transition = create(vm, structure, deferred);
588
589 PropertyTable* table = structure->copyPropertyTableForPinning(vm);
590 transition->pin(holdLock(transition->m_lock), vm, table);
591 transition->m_offset = structure->m_offset;
592 transition->setDictionaryKind(kind);
593 transition->setHasBeenDictionary(true);
594
595 transition->checkOffsetConsistency();
596 return transition;
597}
598
599Structure* Structure::toCacheableDictionaryTransition(VM& vm, Structure* structure, DeferredStructureTransitionWatchpointFire* deferred)
600{
601 return toDictionaryTransition(vm, structure, CachedDictionaryKind, deferred);
602}
603
604Structure* Structure::toUncacheableDictionaryTransition(VM& vm, Structure* structure)
605{
606 return toDictionaryTransition(vm, structure, UncachedDictionaryKind);
607}
608
609Structure* Structure::sealTransition(VM& vm, Structure* structure)
610{
611 return nonPropertyTransition(vm, structure, NonPropertyTransition::Seal);
612}
613
614Structure* Structure::freezeTransition(VM& vm, Structure* structure)
615{
616 return nonPropertyTransition(vm, structure, NonPropertyTransition::Freeze);
617}
618
619Structure* Structure::preventExtensionsTransition(VM& vm, Structure* structure)
620{
621 return nonPropertyTransition(vm, structure, NonPropertyTransition::PreventExtensions);
622}
623
624PropertyTable* Structure::takePropertyTableOrCloneIfPinned(VM& vm)
625{
626 // This must always return a property table. It can't return null.
627 PropertyTable* result = propertyTableOrNull();
628 if (result) {
629 if (isPinnedPropertyTable())
630 return result->copy(vm, result->size() + 1);
631 ConcurrentJSLocker locker(m_lock);
632 setPropertyTable(vm, nullptr);
633 return result;
634 }
635 bool setPropertyTable = false;
636 return materializePropertyTable(vm, setPropertyTable);
637}
638
639Structure* Structure::nonPropertyTransitionSlow(VM& vm, Structure* structure, NonPropertyTransition transitionKind)
640{
641 unsigned attributes = toAttributes(transitionKind);
642 IndexingType indexingModeIncludingHistory = newIndexingType(structure->indexingModeIncludingHistory(), transitionKind);
643
644 Structure* existingTransition;
645 if (!structure->isDictionary() && (existingTransition = structure->m_transitionTable.get(0, attributes))) {
646 ASSERT(existingTransition->attributesInPrevious() == attributes);
647 ASSERT(existingTransition->indexingModeIncludingHistory() == indexingModeIncludingHistory);
648 return existingTransition;
649 }
650
651 DeferGC deferGC(vm.heap);
652
653 Structure* transition = create(vm, structure);
654 transition->setAttributesInPrevious(attributes);
655 transition->m_blob.setIndexingModeIncludingHistory(indexingModeIncludingHistory);
656
657 if (preventsExtensions(transitionKind))
658 transition->setDidPreventExtensions(true);
659
660 if (setsDontDeleteOnAllProperties(transitionKind)
661 || setsReadOnlyOnNonAccessorProperties(transitionKind)) {
662 // We pin the property table on transitions that do wholesale editing of the property
663 // table, since our logic for walking the property transition chain to rematerialize the
664 // table doesn't know how to take into account such wholesale edits.
665
666 PropertyTable* table = structure->copyPropertyTableForPinning(vm);
667 transition->pinForCaching(holdLock(transition->m_lock), vm, table);
668 transition->m_offset = structure->m_offset;
669
670 table = transition->propertyTableOrNull();
671 RELEASE_ASSERT(table);
672 for (auto& entry : *table) {
673 if (setsDontDeleteOnAllProperties(transitionKind))
674 entry.attributes |= static_cast<unsigned>(PropertyAttribute::DontDelete);
675 if (setsReadOnlyOnNonAccessorProperties(transitionKind) && !(entry.attributes & PropertyAttribute::Accessor))
676 entry.attributes |= static_cast<unsigned>(PropertyAttribute::ReadOnly);
677 }
678 } else {
679 transition->setPropertyTable(vm, structure->takePropertyTableOrCloneIfPinned(vm));
680 transition->m_offset = structure->m_offset;
681 checkOffset(transition->m_offset, transition->inlineCapacity());
682 }
683
684 if (setsReadOnlyOnNonAccessorProperties(transitionKind)
685 && !transition->propertyTableOrNull()->isEmpty())
686 transition->setHasReadOnlyOrGetterSetterPropertiesExcludingProto(true);
687
688 if (structure->isDictionary()) {
689 PropertyTable* table = transition->ensurePropertyTable(vm);
690 transition->pin(holdLock(transition->m_lock), vm, table);
691 } else {
692 auto locker = holdLock(structure->m_lock);
693 structure->m_transitionTable.add(vm, transition);
694 }
695
696 transition->checkOffsetConsistency();
697 return transition;
698}
699
700// In future we may want to cache this property.
701bool Structure::isSealed(VM& vm)
702{
703 if (isStructureExtensible())
704 return false;
705
706 PropertyTable* table = ensurePropertyTableIfNotEmpty(vm);
707 if (!table)
708 return true;
709
710 PropertyTable::iterator end = table->end();
711 for (PropertyTable::iterator iter = table->begin(); iter != end; ++iter) {
712 if ((iter->attributes & PropertyAttribute::DontDelete) != static_cast<unsigned>(PropertyAttribute::DontDelete))
713 return false;
714 }
715 return true;
716}
717
718// In future we may want to cache this property.
719bool Structure::isFrozen(VM& vm)
720{
721 if (isStructureExtensible())
722 return false;
723
724 PropertyTable* table = ensurePropertyTableIfNotEmpty(vm);
725 if (!table)
726 return true;
727
728 PropertyTable::iterator end = table->end();
729 for (PropertyTable::iterator iter = table->begin(); iter != end; ++iter) {
730 if (!(iter->attributes & PropertyAttribute::DontDelete))
731 return false;
732 if (!(iter->attributes & (PropertyAttribute::ReadOnly | PropertyAttribute::Accessor)))
733 return false;
734 }
735 return true;
736}
737
738Structure* Structure::flattenDictionaryStructure(VM& vm, JSObject* object)
739{
740 checkOffsetConsistency();
741 ASSERT(isDictionary());
742
743 GCSafeConcurrentJSLocker locker(m_lock, vm.heap);
744
745 object->setStructureIDDirectly(nuke(id()));
746 WTF::storeStoreFence();
747
748 size_t beforeOutOfLineCapacity = this->outOfLineCapacity();
749 if (isUncacheableDictionary()) {
750 PropertyTable* table = propertyTableOrNull();
751 ASSERT(table);
752
753 size_t propertyCount = table->size();
754
755 // Holds our values compacted by insertion order.
756 Vector<JSValue> values(propertyCount);
757
758 // Copies out our values from their hashed locations, compacting property table offsets as we go.
759 unsigned i = 0;
760 PropertyTable::iterator end = table->end();
761 m_offset = invalidOffset;
762 for (PropertyTable::iterator iter = table->begin(); iter != end; ++iter, ++i) {
763 values[i] = object->getDirect(iter->offset);
764 m_offset = iter->offset = offsetForPropertyNumber(i, m_inlineCapacity);
765 }
766
767 // Copies in our values to their compacted locations.
768 for (unsigned i = 0; i < propertyCount; i++)
769 object->putDirect(vm, offsetForPropertyNumber(i, m_inlineCapacity), values[i]);
770
771 table->clearDeletedOffsets();
772
773 // We need to zero our unused property space; otherwise the GC might see a
774 // stale pointer when we add properties in the future.
775 memset(
776 object->inlineStorageUnsafe() + inlineSize(),
777 0,
778 (inlineCapacity() - inlineSize()) * sizeof(EncodedJSValue));
779
780 Butterfly* butterfly = object->butterfly();
781 size_t preCapacity = butterfly->indexingHeader()->preCapacity(this);
782 void* base = butterfly->base(preCapacity, beforeOutOfLineCapacity);
783 void* startOfPropertyStorageSlots = reinterpret_cast<EncodedJSValue*>(base) + preCapacity;
784 memset(startOfPropertyStorageSlots, 0, (beforeOutOfLineCapacity - outOfLineSize()) * sizeof(EncodedJSValue));
785 checkOffsetConsistency();
786 }
787
788 setDictionaryKind(NoneDictionaryKind);
789 setHasBeenFlattenedBefore(true);
790
791 size_t afterOutOfLineCapacity = this->outOfLineCapacity();
792
793 if (object->butterfly() && beforeOutOfLineCapacity != afterOutOfLineCapacity) {
794 ASSERT(beforeOutOfLineCapacity > afterOutOfLineCapacity);
795 // If the object had a Butterfly but after flattening/compacting we no longer have need of it,
796 // we need to zero it out because the collector depends on the Structure to know the size for copying.
797 if (!afterOutOfLineCapacity && !this->hasIndexingHeader(object))
798 object->setButterfly(vm, nullptr);
799 // If the object was down-sized to the point where the base of the Butterfly is no longer within the
800 // first CopiedBlock::blockSize bytes, we'll get the wrong answer if we try to mask the base back to
801 // the CopiedBlock header. To prevent this case we need to memmove the Butterfly down.
802 else
803 object->shiftButterflyAfterFlattening(locker, vm, this, afterOutOfLineCapacity);
804 }
805
806 WTF::storeStoreFence();
807 object->setStructureIDDirectly(id());
808
809 // We need to do a writebarrier here because the GC thread might be scanning the butterfly while
810 // we are shuffling properties around. See: https://bugs.webkit.org/show_bug.cgi?id=166989
811 vm.heap.writeBarrier(object);
812
813 return this;
814}
815
816void Structure::pin(const AbstractLocker&, VM& vm, PropertyTable* table)
817{
818 setIsPinnedPropertyTable(true);
819 setPropertyTable(vm, table);
820 clearPreviousID();
821 m_nameInPrevious = nullptr;
822}
823
824void Structure::pinForCaching(const AbstractLocker&, VM& vm, PropertyTable* table)
825{
826 setIsPinnedPropertyTable(true);
827 setPropertyTable(vm, table);
828 m_nameInPrevious = nullptr;
829}
830
831void Structure::allocateRareData(VM& vm)
832{
833 ASSERT(!hasRareData());
834 StructureRareData* rareData = StructureRareData::create(vm, previousID());
835 WTF::storeStoreFence();
836 m_previousOrRareData.set(vm, this, rareData);
837 ASSERT(hasRareData());
838}
839
840WatchpointSet* Structure::ensurePropertyReplacementWatchpointSet(VM& vm, PropertyOffset offset)
841{
842 ASSERT(!isUncacheableDictionary());
843
844 // In some places it's convenient to call this with an invalid offset. So, we do the check here.
845 if (!isValidOffset(offset))
846 return nullptr;
847
848 if (!hasRareData())
849 allocateRareData(vm);
850 ConcurrentJSLocker locker(m_lock);
851 StructureRareData* rareData = this->rareData();
852 if (!rareData->m_replacementWatchpointSets) {
853 rareData->m_replacementWatchpointSets =
854 std::make_unique<StructureRareData::PropertyWatchpointMap>();
855 WTF::storeStoreFence();
856 }
857 auto result = rareData->m_replacementWatchpointSets->add(offset, nullptr);
858 if (result.isNewEntry)
859 result.iterator->value = adoptRef(new WatchpointSet(IsWatched));
860 return result.iterator->value.get();
861}
862
863void Structure::startWatchingPropertyForReplacements(VM& vm, PropertyName propertyName)
864{
865 ASSERT(!isUncacheableDictionary());
866
867 startWatchingPropertyForReplacements(vm, get(vm, propertyName));
868}
869
870void Structure::didCachePropertyReplacement(VM& vm, PropertyOffset offset)
871{
872 RELEASE_ASSERT(isValidOffset(offset));
873 ensurePropertyReplacementWatchpointSet(vm, offset)->fireAll(vm, "Did cache property replacement");
874}
875
876void Structure::startWatchingInternalProperties(VM& vm)
877{
878 if (!isUncacheableDictionary()) {
879 startWatchingPropertyForReplacements(vm, vm.propertyNames->toString);
880 startWatchingPropertyForReplacements(vm, vm.propertyNames->valueOf);
881 }
882 setDidWatchInternalProperties(true);
883}
884
885#if DUMP_PROPERTYMAP_STATS
886
887PropertyMapHashTableStats* propertyMapHashTableStats = 0;
888
889struct PropertyMapStatisticsExitLogger {
890 PropertyMapStatisticsExitLogger();
891 ~PropertyMapStatisticsExitLogger();
892};
893
894DEFINE_GLOBAL_FOR_LOGGING(PropertyMapStatisticsExitLogger, logger, );
895
896PropertyMapStatisticsExitLogger::PropertyMapStatisticsExitLogger()
897{
898 propertyMapHashTableStats = adoptPtr(new PropertyMapHashTableStats()).leakPtr();
899}
900
901PropertyMapStatisticsExitLogger::~PropertyMapStatisticsExitLogger()
902{
903 unsigned finds = propertyMapHashTableStats->numFinds;
904 unsigned collisions = propertyMapHashTableStats->numCollisions;
905 dataLogF("\nJSC::PropertyMap statistics for process %d\n\n", getCurrentProcessID());
906 dataLogF("%d finds\n", finds);
907 dataLogF("%d collisions (%.1f%%)\n", collisions, 100.0 * collisions / finds);
908 dataLogF("%d lookups\n", propertyMapHashTableStats->numLookups.load());
909 dataLogF("%d lookup probings\n", propertyMapHashTableStats->numLookupProbing.load());
910 dataLogF("%d adds\n", propertyMapHashTableStats->numAdds.load());
911 dataLogF("%d removes\n", propertyMapHashTableStats->numRemoves.load());
912 dataLogF("%d rehashes\n", propertyMapHashTableStats->numRehashes.load());
913 dataLogF("%d reinserts\n", propertyMapHashTableStats->numReinserts.load());
914}
915
916#endif
917
918PropertyTable* Structure::copyPropertyTableForPinning(VM& vm)
919{
920 if (PropertyTable* table = propertyTableOrNull())
921 return PropertyTable::clone(vm, *table);
922 bool setPropertyTable = false;
923 return materializePropertyTable(vm, setPropertyTable);
924}
925
926PropertyOffset Structure::getConcurrently(UniquedStringImpl* uid, unsigned& attributes)
927{
928 PropertyOffset result = invalidOffset;
929
930 forEachPropertyConcurrently(
931 [&] (const PropertyMapEntry& candidate) -> bool {
932 if (candidate.key != uid)
933 return true;
934
935 result = candidate.offset;
936 attributes = candidate.attributes;
937 return false;
938 });
939
940 return result;
941}
942
943Vector<PropertyMapEntry> Structure::getPropertiesConcurrently()
944{
945 Vector<PropertyMapEntry> result;
946
947 forEachPropertyConcurrently(
948 [&] (const PropertyMapEntry& entry) -> bool {
949 result.append(entry);
950 return true;
951 });
952
953 return result;
954}
955
956PropertyOffset Structure::add(VM& vm, PropertyName propertyName, unsigned attributes)
957{
958 return add<ShouldPin::No>(
959 vm, propertyName, attributes,
960 [this] (const GCSafeConcurrentJSLocker&, PropertyOffset, PropertyOffset newLastOffset) {
961 setLastOffset(newLastOffset);
962 });
963}
964
965PropertyOffset Structure::remove(PropertyName propertyName)
966{
967 return remove(propertyName, [] (const ConcurrentJSLocker&, PropertyOffset) { });
968}
969
970void Structure::getPropertyNamesFromStructure(VM& vm, PropertyNameArray& propertyNames, EnumerationMode mode)
971{
972 PropertyTable* table = ensurePropertyTableIfNotEmpty(vm);
973 if (!table)
974 return;
975
976 bool knownUnique = propertyNames.canAddKnownUniqueForStructure();
977
978 PropertyTable::iterator end = table->end();
979 for (PropertyTable::iterator iter = table->begin(); iter != end; ++iter) {
980 ASSERT(!isQuickPropertyAccessAllowedForEnumeration() || !(iter->attributes & PropertyAttribute::DontEnum));
981 ASSERT(!isQuickPropertyAccessAllowedForEnumeration() || !iter->key->isSymbol());
982 if (!(iter->attributes & PropertyAttribute::DontEnum) || mode.includeDontEnumProperties()) {
983 if (iter->key->isSymbol() && !propertyNames.includeSymbolProperties())
984 continue;
985 if (knownUnique)
986 propertyNames.addUnchecked(iter->key);
987 else
988 propertyNames.add(iter->key);
989 }
990 }
991}
992
993void StructureFireDetail::dump(PrintStream& out) const
994{
995 out.print("Structure transition from ", *m_structure);
996}
997
998DeferredStructureTransitionWatchpointFire::DeferredStructureTransitionWatchpointFire(VM& vm, Structure* structure)
999 : DeferredWatchpointFire(vm)
1000 , m_structure(structure)
1001{
1002}
1003
1004DeferredStructureTransitionWatchpointFire::~DeferredStructureTransitionWatchpointFire()
1005{
1006 fireAll();
1007}
1008
1009void DeferredStructureTransitionWatchpointFire::dump(PrintStream& out) const
1010{
1011 out.print("Structure transition from ", *m_structure);
1012}
1013
1014void Structure::didTransitionFromThisStructure(DeferredStructureTransitionWatchpointFire* deferred) const
1015{
1016 // If the structure is being watched, and this is the kind of structure that the DFG would
1017 // like to watch, then make sure to note for all future versions of this structure that it's
1018 // unwise to watch it.
1019 if (m_transitionWatchpointSet.isBeingWatched())
1020 const_cast<Structure*>(this)->setTransitionWatchpointIsLikelyToBeFired(true);
1021
1022 if (deferred) {
1023 ASSERT(deferred->structure() == this);
1024 m_transitionWatchpointSet.fireAll(*vm(), deferred);
1025 } else
1026 m_transitionWatchpointSet.fireAll(*vm(), StructureFireDetail(this));
1027}
1028
1029void Structure::visitChildren(JSCell* cell, SlotVisitor& visitor)
1030{
1031 Structure* thisObject = jsCast<Structure*>(cell);
1032 ASSERT_GC_OBJECT_INHERITS(thisObject, info());
1033
1034 Base::visitChildren(thisObject, visitor);
1035
1036 ConcurrentJSLocker locker(thisObject->m_lock);
1037
1038 visitor.append(thisObject->m_globalObject);
1039 if (!thisObject->isObject())
1040 thisObject->m_cachedPrototypeChain.clear();
1041 else {
1042 visitor.append(thisObject->m_prototype);
1043 visitor.append(thisObject->m_cachedPrototypeChain);
1044 }
1045 visitor.append(thisObject->m_previousOrRareData);
1046
1047 if (thisObject->isPinnedPropertyTable() || thisObject->isAddingPropertyForTransition()) {
1048 // NOTE: This can interleave in pin(), in which case it may see a null property table.
1049 // That's fine, because then the barrier will fire and we will scan this again.
1050 visitor.append(thisObject->m_propertyTableUnsafe);
1051 } else if (visitor.isBuildingHeapSnapshot())
1052 visitor.append(thisObject->m_propertyTableUnsafe);
1053 else if (thisObject->m_propertyTableUnsafe)
1054 thisObject->m_propertyTableUnsafe.clear();
1055}
1056
1057bool Structure::isCheapDuringGC(VM& vm)
1058{
1059 // FIXME: We could make this even safer by returning false if this structure's property table
1060 // has any large property names.
1061 // https://bugs.webkit.org/show_bug.cgi?id=157334
1062
1063 return (!m_globalObject || vm.heap.isMarked(m_globalObject.get()))
1064 && (hasPolyProto() || !storedPrototypeObject() || vm.heap.isMarked(storedPrototypeObject()));
1065}
1066
1067bool Structure::markIfCheap(SlotVisitor& visitor)
1068{
1069 VM& vm = visitor.vm();
1070 if (!isCheapDuringGC(vm))
1071 return vm.heap.isMarked(this);
1072
1073 visitor.appendUnbarriered(this);
1074 return true;
1075}
1076
1077Ref<StructureShape> Structure::toStructureShape(JSValue value, bool& sawPolyProtoStructure)
1078{
1079 Ref<StructureShape> baseShape = StructureShape::create();
1080 RefPtr<StructureShape> curShape = baseShape.ptr();
1081 Structure* curStructure = this;
1082 JSValue curValue = value;
1083 sawPolyProtoStructure = false;
1084 while (curStructure) {
1085 sawPolyProtoStructure |= curStructure->hasPolyProto();
1086 curStructure->forEachPropertyConcurrently(
1087 [&] (const PropertyMapEntry& entry) -> bool {
1088 if (!PropertyName(entry.key).isPrivateName())
1089 curShape->addProperty(*entry.key);
1090 return true;
1091 });
1092
1093 if (JSObject* curObject = curValue.getObject())
1094 curShape->setConstructorName(JSObject::calculatedClassName(curObject));
1095 else
1096 curShape->setConstructorName(curStructure->classInfo()->className);
1097
1098 if (curStructure->isDictionary())
1099 curShape->enterDictionaryMode();
1100
1101 curShape->markAsFinal();
1102
1103 if (!curValue.isObject())
1104 break;
1105
1106 JSObject* object = asObject(curValue);
1107 JSObject* prototypeObject = object->structure()->storedPrototypeObject(object);
1108 if (!prototypeObject)
1109 break;
1110
1111 auto newShape = StructureShape::create();
1112 curShape->setProto(newShape.copyRef());
1113 curShape = WTFMove(newShape);
1114 curValue = prototypeObject;
1115 curStructure = prototypeObject->structure();
1116 }
1117
1118 return baseShape;
1119}
1120
1121void Structure::dump(PrintStream& out) const
1122{
1123 out.print(RawPointer(this), ":[", classInfo()->className, ", {");
1124
1125 CommaPrinter comma;
1126
1127 const_cast<Structure*>(this)->forEachPropertyConcurrently(
1128 [&] (const PropertyMapEntry& entry) -> bool {
1129 out.print(comma, entry.key, ":", static_cast<int>(entry.offset));
1130 return true;
1131 });
1132
1133 out.print("}, ", IndexingTypeDump(indexingMode()));
1134
1135 if (hasPolyProto())
1136 out.print(", PolyProto offset:", knownPolyProtoOffset);
1137 else if (m_prototype.get().isCell())
1138 out.print(", Proto:", RawPointer(m_prototype.get().asCell()));
1139
1140 switch (dictionaryKind()) {
1141 case NoneDictionaryKind:
1142 if (hasBeenDictionary())
1143 out.print(", Has been dictionary");
1144 break;
1145 case CachedDictionaryKind:
1146 out.print(", Dictionary");
1147 break;
1148 case UncachedDictionaryKind:
1149 out.print(", UncacheableDictionary");
1150 break;
1151 }
1152
1153 if (transitionWatchpointSetIsStillValid())
1154 out.print(", Leaf");
1155 else if (transitionWatchpointIsLikelyToBeFired())
1156 out.print(", Shady leaf");
1157
1158 out.print("]");
1159}
1160
1161void Structure::dumpInContext(PrintStream& out, DumpContext* context) const
1162{
1163 if (context)
1164 context->structures.dumpBrief(this, out);
1165 else
1166 dump(out);
1167}
1168
1169void Structure::dumpBrief(PrintStream& out, const CString& string) const
1170{
1171 out.print("%", string, ":", classInfo()->className);
1172}
1173
1174void Structure::dumpContextHeader(PrintStream& out)
1175{
1176 out.print("Structures:");
1177}
1178
1179bool ClassInfo::hasStaticSetterOrReadonlyProperties() const
1180{
1181 for (const ClassInfo* ci = this; ci; ci = ci->parentClass) {
1182 if (const HashTable* table = ci->staticPropHashTable) {
1183 if (table->hasSetterOrReadonlyProperties)
1184 return true;
1185 }
1186 }
1187 return false;
1188}
1189
1190void Structure::setCachedPropertyNameEnumerator(VM& vm, JSPropertyNameEnumerator* enumerator)
1191{
1192 ASSERT(!isDictionary());
1193 if (!hasRareData())
1194 allocateRareData(vm);
1195 rareData()->setCachedPropertyNameEnumerator(vm, enumerator);
1196}
1197
1198JSPropertyNameEnumerator* Structure::cachedPropertyNameEnumerator() const
1199{
1200 if (!hasRareData())
1201 return nullptr;
1202 return rareData()->cachedPropertyNameEnumerator();
1203}
1204
1205bool Structure::canCachePropertyNameEnumerator() const
1206{
1207 if (!this->canCacheOwnKeys())
1208 return false;
1209
1210 StructureChain* structureChain = m_cachedPrototypeChain.get();
1211 ASSERT(structureChain);
1212 WriteBarrier<Structure>* structure = structureChain->head();
1213 while (true) {
1214 if (!structure->get())
1215 return true;
1216 if (!structure->get()->canCacheOwnKeys())
1217 return false;
1218 structure++;
1219 }
1220
1221 ASSERT_NOT_REACHED();
1222 return true;
1223}
1224
1225bool Structure::canAccessPropertiesQuicklyForEnumeration() const
1226{
1227 if (!isQuickPropertyAccessAllowedForEnumeration())
1228 return false;
1229 if (hasGetterSetterProperties())
1230 return false;
1231 if (isUncacheableDictionary())
1232 return false;
1233 return true;
1234}
1235
1236} // namespace JSC
1237