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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_HEAP_HEAP_INL_H_
6 #define V8_HEAP_HEAP_INL_H_
7 
8 #include <cmath>
9 
10 // Clients of this interface shouldn't depend on lots of heap internals.
11 // Do not include anything from src/heap other than src/heap/heap.h and its
12 // write barrier here!
13 #include "src/heap/heap-write-barrier.h"
14 #include "src/heap/heap.h"
15 
16 #include "src/base/platform/platform.h"
17 #include "src/counters-inl.h"
18 #include "src/feedback-vector.h"
19 
20 // TODO(mstarzinger): There is one more include to remove in order to no longer
21 // leak heap internals to users of this interface!
22 #include "src/heap/spaces-inl.h"
23 #include "src/isolate.h"
24 #include "src/log.h"
25 #include "src/msan.h"
26 #include "src/objects-inl.h"
27 #include "src/objects/api-callbacks-inl.h"
28 #include "src/objects/descriptor-array.h"
29 #include "src/objects/literal-objects.h"
30 #include "src/objects/scope-info.h"
31 #include "src/objects/script-inl.h"
32 #include "src/profiler/heap-profiler.h"
33 #include "src/string-hasher.h"
34 #include "src/zone/zone-list-inl.h"
35 
36 // The following header includes the write barrier essentials that can also be
37 // used stand-alone without including heap-inl.h.
38 // TODO(mlippautz): Remove once users of object-macros.h include this file on
39 // their own.
40 #include "src/heap/heap-write-barrier-inl.h"
41 
42 namespace v8 {
43 namespace internal {
44 
RetrySpace()45 AllocationSpace AllocationResult::RetrySpace() {
46   DCHECK(IsRetry());
47   return static_cast<AllocationSpace>(Smi::ToInt(object_));
48 }
49 
ToObjectChecked()50 HeapObject* AllocationResult::ToObjectChecked() {
51   CHECK(!IsRetry());
52   return HeapObject::cast(object_);
53 }
54 
55 #define ROOT_ACCESSOR(type, name, camel_name) \
56   type* Heap::name() { return type::cast(roots_[k##camel_name##RootIndex]); }
57 MUTABLE_ROOT_LIST(ROOT_ACCESSOR)
58 #undef ROOT_ACCESSOR
59 
60 #define DATA_HANDLER_MAP_ACCESSOR(NAME, Name, Size, name)  \
61   Map* Heap::name##_map() {                                \
62     return Map::cast(roots_[k##Name##Size##MapRootIndex]); \
63   }
DATA_HANDLER_LIST(DATA_HANDLER_MAP_ACCESSOR)64 DATA_HANDLER_LIST(DATA_HANDLER_MAP_ACCESSOR)
65 #undef DATA_HANDLER_MAP_ACCESSOR
66 
67 #define ACCESSOR_INFO_ACCESSOR(accessor_name, AccessorName)                \
68   AccessorInfo* Heap::accessor_name##_accessor() {                         \
69     return AccessorInfo::cast(roots_[k##AccessorName##AccessorRootIndex]); \
70   }
71 ACCESSOR_INFO_LIST(ACCESSOR_INFO_ACCESSOR)
72 #undef ACCESSOR_INFO_ACCESSOR
73 
74 #define ROOT_ACCESSOR(type, name, camel_name)                                 \
75   void Heap::set_##name(type* value) {                                        \
76     /* The deserializer makes use of the fact that these common roots are */  \
77     /* never in new space and never on a page that is being compacted.    */  \
78     DCHECK(!deserialization_complete() ||                                     \
79            RootCanBeWrittenAfterInitialization(k##camel_name##RootIndex));    \
80     DCHECK(k##camel_name##RootIndex >= kOldSpaceRoots || !InNewSpace(value)); \
81     roots_[k##camel_name##RootIndex] = value;                                 \
82   }
83 ROOT_LIST(ROOT_ACCESSOR)
84 #undef ROOT_ACCESSOR
85 
86 PagedSpace* Heap::paged_space(int idx) {
87   DCHECK_NE(idx, LO_SPACE);
88   DCHECK_NE(idx, NEW_SPACE);
89   return static_cast<PagedSpace*>(space_[idx]);
90 }
91 
space(int idx)92 Space* Heap::space(int idx) { return space_[idx]; }
93 
NewSpaceAllocationTopAddress()94 Address* Heap::NewSpaceAllocationTopAddress() {
95   return new_space_->allocation_top_address();
96 }
97 
NewSpaceAllocationLimitAddress()98 Address* Heap::NewSpaceAllocationLimitAddress() {
99   return new_space_->allocation_limit_address();
100 }
101 
OldSpaceAllocationTopAddress()102 Address* Heap::OldSpaceAllocationTopAddress() {
103   return old_space_->allocation_top_address();
104 }
105 
OldSpaceAllocationLimitAddress()106 Address* Heap::OldSpaceAllocationLimitAddress() {
107   return old_space_->allocation_limit_address();
108 }
109 
UpdateNewSpaceAllocationCounter()110 void Heap::UpdateNewSpaceAllocationCounter() {
111   new_space_allocation_counter_ = NewSpaceAllocationCounter();
112 }
113 
NewSpaceAllocationCounter()114 size_t Heap::NewSpaceAllocationCounter() {
115   return new_space_allocation_counter_ + new_space()->AllocatedSinceLastGC();
116 }
117 
AllocateRaw(int size_in_bytes,AllocationSpace space,AllocationAlignment alignment)118 AllocationResult Heap::AllocateRaw(int size_in_bytes, AllocationSpace space,
119                                    AllocationAlignment alignment) {
120   DCHECK(AllowHandleAllocation::IsAllowed());
121   DCHECK(AllowHeapAllocation::IsAllowed());
122   DCHECK(gc_state_ == NOT_IN_GC);
123 #ifdef V8_ENABLE_ALLOCATION_TIMEOUT
124   if (FLAG_random_gc_interval > 0 || FLAG_gc_interval >= 0) {
125     if (!always_allocate() && Heap::allocation_timeout_-- <= 0) {
126       return AllocationResult::Retry(space);
127     }
128   }
129 #endif
130 #ifdef DEBUG
131   isolate_->counters()->objs_since_last_full()->Increment();
132   isolate_->counters()->objs_since_last_young()->Increment();
133 #endif
134 
135   bool large_object = size_in_bytes > kMaxRegularHeapObjectSize;
136   bool new_large_object = FLAG_young_generation_large_objects &&
137                           size_in_bytes > kMaxNewSpaceHeapObjectSize;
138   HeapObject* object = nullptr;
139   AllocationResult allocation;
140   if (NEW_SPACE == space) {
141     if (large_object) {
142       space = LO_SPACE;
143     } else {
144       if (new_large_object) {
145         allocation = new_lo_space_->AllocateRaw(size_in_bytes);
146       } else {
147         allocation = new_space_->AllocateRaw(size_in_bytes, alignment);
148       }
149       if (allocation.To(&object)) {
150         OnAllocationEvent(object, size_in_bytes);
151       }
152       return allocation;
153     }
154   }
155 
156   // Here we only allocate in the old generation.
157   if (OLD_SPACE == space) {
158     if (large_object) {
159       allocation = lo_space_->AllocateRaw(size_in_bytes, NOT_EXECUTABLE);
160     } else {
161       allocation = old_space_->AllocateRaw(size_in_bytes, alignment);
162     }
163   } else if (CODE_SPACE == space) {
164     if (size_in_bytes <= code_space()->AreaSize()) {
165       allocation = code_space_->AllocateRawUnaligned(size_in_bytes);
166     } else {
167       allocation = lo_space_->AllocateRaw(size_in_bytes, EXECUTABLE);
168     }
169   } else if (LO_SPACE == space) {
170     DCHECK(large_object);
171     allocation = lo_space_->AllocateRaw(size_in_bytes, NOT_EXECUTABLE);
172   } else if (MAP_SPACE == space) {
173     allocation = map_space_->AllocateRawUnaligned(size_in_bytes);
174   } else if (RO_SPACE == space) {
175 #ifdef V8_USE_SNAPSHOT
176     DCHECK(isolate_->serializer_enabled());
177 #endif
178     DCHECK(!large_object);
179     DCHECK(CanAllocateInReadOnlySpace());
180     allocation = read_only_space_->AllocateRaw(size_in_bytes, alignment);
181   } else {
182     // NEW_SPACE is not allowed here.
183     UNREACHABLE();
184   }
185 
186   if (allocation.To(&object)) {
187     if (space == CODE_SPACE) {
188       // Unprotect the memory chunk of the object if it was not unprotected
189       // already.
190       UnprotectAndRegisterMemoryChunk(object);
191       ZapCodeObject(object->address(), size_in_bytes);
192     }
193     OnAllocationEvent(object, size_in_bytes);
194   }
195 
196   return allocation;
197 }
198 
OnAllocationEvent(HeapObject * object,int size_in_bytes)199 void Heap::OnAllocationEvent(HeapObject* object, int size_in_bytes) {
200   for (auto& tracker : allocation_trackers_) {
201     tracker->AllocationEvent(object->address(), size_in_bytes);
202   }
203 
204   if (FLAG_verify_predictable) {
205     ++allocations_count_;
206     // Advance synthetic time by making a time request.
207     MonotonicallyIncreasingTimeInMs();
208 
209     UpdateAllocationsHash(object);
210     UpdateAllocationsHash(size_in_bytes);
211 
212     if (allocations_count_ % FLAG_dump_allocations_digest_at_alloc == 0) {
213       PrintAllocationsHash();
214     }
215   } else if (FLAG_fuzzer_gc_analysis) {
216     ++allocations_count_;
217   } else if (FLAG_trace_allocation_stack_interval > 0) {
218     ++allocations_count_;
219     if (allocations_count_ % FLAG_trace_allocation_stack_interval == 0) {
220       isolate()->PrintStack(stdout, Isolate::kPrintStackConcise);
221     }
222   }
223 }
224 
225 
OnMoveEvent(HeapObject * target,HeapObject * source,int size_in_bytes)226 void Heap::OnMoveEvent(HeapObject* target, HeapObject* source,
227                        int size_in_bytes) {
228   HeapProfiler* heap_profiler = isolate_->heap_profiler();
229   if (heap_profiler->is_tracking_object_moves()) {
230     heap_profiler->ObjectMoveEvent(source->address(), target->address(),
231                                    size_in_bytes);
232   }
233   for (auto& tracker : allocation_trackers_) {
234     tracker->MoveEvent(source->address(), target->address(), size_in_bytes);
235   }
236   if (target->IsSharedFunctionInfo()) {
237     LOG_CODE_EVENT(isolate_, SharedFunctionInfoMoveEvent(source->address(),
238                                                          target->address()));
239   }
240 
241   if (FLAG_verify_predictable) {
242     ++allocations_count_;
243     // Advance synthetic time by making a time request.
244     MonotonicallyIncreasingTimeInMs();
245 
246     UpdateAllocationsHash(source);
247     UpdateAllocationsHash(target);
248     UpdateAllocationsHash(size_in_bytes);
249 
250     if (allocations_count_ % FLAG_dump_allocations_digest_at_alloc == 0) {
251       PrintAllocationsHash();
252     }
253   } else if (FLAG_fuzzer_gc_analysis) {
254     ++allocations_count_;
255   }
256 }
257 
CanAllocateInReadOnlySpace()258 bool Heap::CanAllocateInReadOnlySpace() {
259   return !deserialization_complete_ &&
260          (isolate()->serializer_enabled() ||
261           !isolate()->initialized_from_snapshot());
262 }
263 
UpdateAllocationsHash(HeapObject * object)264 void Heap::UpdateAllocationsHash(HeapObject* object) {
265   Address object_address = object->address();
266   MemoryChunk* memory_chunk = MemoryChunk::FromAddress(object_address);
267   AllocationSpace allocation_space = memory_chunk->owner()->identity();
268 
269   STATIC_ASSERT(kSpaceTagSize + kPageSizeBits <= 32);
270   uint32_t value =
271       static_cast<uint32_t>(object_address - memory_chunk->address()) |
272       (static_cast<uint32_t>(allocation_space) << kPageSizeBits);
273 
274   UpdateAllocationsHash(value);
275 }
276 
277 
UpdateAllocationsHash(uint32_t value)278 void Heap::UpdateAllocationsHash(uint32_t value) {
279   uint16_t c1 = static_cast<uint16_t>(value);
280   uint16_t c2 = static_cast<uint16_t>(value >> 16);
281   raw_allocations_hash_ =
282       StringHasher::AddCharacterCore(raw_allocations_hash_, c1);
283   raw_allocations_hash_ =
284       StringHasher::AddCharacterCore(raw_allocations_hash_, c2);
285 }
286 
287 
RegisterExternalString(String * string)288 void Heap::RegisterExternalString(String* string) {
289   DCHECK(string->IsExternalString());
290   DCHECK(!string->IsThinString());
291   external_string_table_.AddString(string);
292 }
293 
UpdateExternalString(String * string,size_t old_payload,size_t new_payload)294 void Heap::UpdateExternalString(String* string, size_t old_payload,
295                                 size_t new_payload) {
296   DCHECK(string->IsExternalString());
297   Page* page = Page::FromHeapObject(string);
298 
299   if (old_payload > new_payload)
300     page->DecrementExternalBackingStoreBytes(
301         ExternalBackingStoreType::kExternalString, old_payload - new_payload);
302   else
303     page->IncrementExternalBackingStoreBytes(
304         ExternalBackingStoreType::kExternalString, new_payload - old_payload);
305 }
306 
FinalizeExternalString(String * string)307 void Heap::FinalizeExternalString(String* string) {
308   DCHECK(string->IsExternalString());
309   Page* page = Page::FromHeapObject(string);
310   ExternalString* ext_string = ExternalString::cast(string);
311 
312   page->DecrementExternalBackingStoreBytes(
313       ExternalBackingStoreType::kExternalString,
314       ext_string->ExternalPayloadSize());
315 
316   v8::String::ExternalStringResourceBase** resource_addr =
317       reinterpret_cast<v8::String::ExternalStringResourceBase**>(
318           reinterpret_cast<byte*>(string) + ExternalString::kResourceOffset -
319           kHeapObjectTag);
320 
321   // Dispose of the C++ object if it has not already been disposed.
322   if (*resource_addr != nullptr) {
323     (*resource_addr)->Dispose();
324     *resource_addr = nullptr;
325   }
326 }
327 
NewSpaceTop()328 Address Heap::NewSpaceTop() { return new_space_->top(); }
329 
330 // static
InNewSpace(Object * object)331 bool Heap::InNewSpace(Object* object) {
332   DCHECK(!HasWeakHeapObjectTag(object));
333   return object->IsHeapObject() && InNewSpace(HeapObject::cast(object));
334 }
335 
336 // static
InNewSpace(MaybeObject * object)337 bool Heap::InNewSpace(MaybeObject* object) {
338   HeapObject* heap_object;
339   return object->ToStrongOrWeakHeapObject(&heap_object) &&
340          InNewSpace(heap_object);
341 }
342 
343 // static
InNewSpace(HeapObject * heap_object)344 bool Heap::InNewSpace(HeapObject* heap_object) {
345   // Inlined check from NewSpace::Contains.
346   bool result = MemoryChunk::FromHeapObject(heap_object)->InNewSpace();
347 #ifdef DEBUG
348   // If in NEW_SPACE, then check we're either not in the middle of GC or the
349   // object is in to-space.
350   if (result) {
351     // If the object is in NEW_SPACE, then it's not in RO_SPACE so this is safe.
352     Heap* heap = Heap::FromWritableHeapObject(heap_object);
353     DCHECK(heap->gc_state_ != NOT_IN_GC || InToSpace(heap_object));
354   }
355 #endif
356   return result;
357 }
358 
359 // static
InFromSpace(Object * object)360 bool Heap::InFromSpace(Object* object) {
361   DCHECK(!HasWeakHeapObjectTag(object));
362   return object->IsHeapObject() && InFromSpace(HeapObject::cast(object));
363 }
364 
365 // static
InFromSpace(MaybeObject * object)366 bool Heap::InFromSpace(MaybeObject* object) {
367   HeapObject* heap_object;
368   return object->ToStrongOrWeakHeapObject(&heap_object) &&
369          InFromSpace(heap_object);
370 }
371 
372 // static
InFromSpace(HeapObject * heap_object)373 bool Heap::InFromSpace(HeapObject* heap_object) {
374   return MemoryChunk::FromHeapObject(heap_object)
375       ->IsFlagSet(Page::IN_FROM_SPACE);
376 }
377 
378 // static
InToSpace(Object * object)379 bool Heap::InToSpace(Object* object) {
380   DCHECK(!HasWeakHeapObjectTag(object));
381   return object->IsHeapObject() && InToSpace(HeapObject::cast(object));
382 }
383 
384 // static
InToSpace(MaybeObject * object)385 bool Heap::InToSpace(MaybeObject* object) {
386   HeapObject* heap_object;
387   return object->ToStrongOrWeakHeapObject(&heap_object) &&
388          InToSpace(heap_object);
389 }
390 
391 // static
InToSpace(HeapObject * heap_object)392 bool Heap::InToSpace(HeapObject* heap_object) {
393   return MemoryChunk::FromHeapObject(heap_object)->IsFlagSet(Page::IN_TO_SPACE);
394 }
395 
InOldSpace(Object * object)396 bool Heap::InOldSpace(Object* object) { return old_space_->Contains(object); }
397 
InReadOnlySpace(Object * object)398 bool Heap::InReadOnlySpace(Object* object) {
399   return read_only_space_->Contains(object);
400 }
401 
InNewSpaceSlow(Address address)402 bool Heap::InNewSpaceSlow(Address address) {
403   return new_space_->ContainsSlow(address);
404 }
405 
InOldSpaceSlow(Address address)406 bool Heap::InOldSpaceSlow(Address address) {
407   return old_space_->ContainsSlow(address);
408 }
409 
410 // static
FromWritableHeapObject(const HeapObject * obj)411 Heap* Heap::FromWritableHeapObject(const HeapObject* obj) {
412   MemoryChunk* chunk = MemoryChunk::FromHeapObject(obj);
413   // RO_SPACE can be shared between heaps, so we can't use RO_SPACE objects to
414   // find a heap. The exception is when the ReadOnlySpace is writeable, during
415   // bootstrapping, so explicitly allow this case.
416   SLOW_DCHECK(chunk->owner()->identity() != RO_SPACE ||
417               static_cast<ReadOnlySpace*>(chunk->owner())->writable());
418   Heap* heap = chunk->heap();
419   SLOW_DCHECK(heap != nullptr);
420   return heap;
421 }
422 
ShouldBePromoted(Address old_address)423 bool Heap::ShouldBePromoted(Address old_address) {
424   Page* page = Page::FromAddress(old_address);
425   Address age_mark = new_space_->age_mark();
426   return page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
427          (!page->ContainsLimit(age_mark) || old_address < age_mark);
428 }
429 
CopyBlock(Address dst,Address src,int byte_size)430 void Heap::CopyBlock(Address dst, Address src, int byte_size) {
431   CopyWords(reinterpret_cast<Object**>(dst), reinterpret_cast<Object**>(src),
432             static_cast<size_t>(byte_size / kPointerSize));
433 }
434 
435 template <Heap::FindMementoMode mode>
FindAllocationMemento(Map * map,HeapObject * object)436 AllocationMemento* Heap::FindAllocationMemento(Map* map, HeapObject* object) {
437   Address object_address = object->address();
438   Address memento_address = object_address + object->SizeFromMap(map);
439   Address last_memento_word_address = memento_address + kPointerSize;
440   // If the memento would be on another page, bail out immediately.
441   if (!Page::OnSamePage(object_address, last_memento_word_address)) {
442     return nullptr;
443   }
444   HeapObject* candidate = HeapObject::FromAddress(memento_address);
445   Map* candidate_map = candidate->map();
446   // This fast check may peek at an uninitialized word. However, the slow check
447   // below (memento_address == top) ensures that this is safe. Mark the word as
448   // initialized to silence MemorySanitizer warnings.
449   MSAN_MEMORY_IS_INITIALIZED(&candidate_map, sizeof(candidate_map));
450   if (candidate_map != ReadOnlyRoots(this).allocation_memento_map()) {
451     return nullptr;
452   }
453 
454   // Bail out if the memento is below the age mark, which can happen when
455   // mementos survived because a page got moved within new space.
456   Page* object_page = Page::FromAddress(object_address);
457   if (object_page->IsFlagSet(Page::NEW_SPACE_BELOW_AGE_MARK)) {
458     Address age_mark =
459         reinterpret_cast<SemiSpace*>(object_page->owner())->age_mark();
460     if (!object_page->Contains(age_mark)) {
461       return nullptr;
462     }
463     // Do an exact check in the case where the age mark is on the same page.
464     if (object_address < age_mark) {
465       return nullptr;
466     }
467   }
468 
469   AllocationMemento* memento_candidate = AllocationMemento::cast(candidate);
470 
471   // Depending on what the memento is used for, we might need to perform
472   // additional checks.
473   Address top;
474   switch (mode) {
475     case Heap::kForGC:
476       return memento_candidate;
477     case Heap::kForRuntime:
478       if (memento_candidate == nullptr) return nullptr;
479       // Either the object is the last object in the new space, or there is
480       // another object of at least word size (the header map word) following
481       // it, so suffices to compare ptr and top here.
482       top = NewSpaceTop();
483       DCHECK(memento_address == top ||
484              memento_address + HeapObject::kHeaderSize <= top ||
485              !Page::OnSamePage(memento_address, top - 1));
486       if ((memento_address != top) && memento_candidate->IsValid()) {
487         return memento_candidate;
488       }
489       return nullptr;
490     default:
491       UNREACHABLE();
492   }
493   UNREACHABLE();
494 }
495 
UpdateAllocationSite(Map * map,HeapObject * object,PretenuringFeedbackMap * pretenuring_feedback)496 void Heap::UpdateAllocationSite(Map* map, HeapObject* object,
497                                 PretenuringFeedbackMap* pretenuring_feedback) {
498   DCHECK_NE(pretenuring_feedback, &global_pretenuring_feedback_);
499   DCHECK(
500       InFromSpace(object) ||
501       (InToSpace(object) && Page::FromAddress(object->address())
502                                 ->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION)) ||
503       (!InNewSpace(object) && Page::FromAddress(object->address())
504                                   ->IsFlagSet(Page::PAGE_NEW_OLD_PROMOTION)));
505   if (!FLAG_allocation_site_pretenuring ||
506       !AllocationSite::CanTrack(map->instance_type()))
507     return;
508   AllocationMemento* memento_candidate =
509       FindAllocationMemento<kForGC>(map, object);
510   if (memento_candidate == nullptr) return;
511 
512   // Entering cached feedback is used in the parallel case. We are not allowed
513   // to dereference the allocation site and rather have to postpone all checks
514   // till actually merging the data.
515   Address key = memento_candidate->GetAllocationSiteUnchecked();
516   (*pretenuring_feedback)[reinterpret_cast<AllocationSite*>(key)]++;
517 }
518 
isolate()519 Isolate* Heap::isolate() {
520   return reinterpret_cast<Isolate*>(
521       reinterpret_cast<intptr_t>(this) -
522       reinterpret_cast<size_t>(reinterpret_cast<Isolate*>(16)->heap()) + 16);
523 }
524 
AddString(String * string)525 void Heap::ExternalStringTable::AddString(String* string) {
526   DCHECK(string->IsExternalString());
527   DCHECK(!Contains(string));
528 
529   if (InNewSpace(string)) {
530     new_space_strings_.push_back(string);
531   } else {
532     old_space_strings_.push_back(string);
533   }
534 }
535 
ToBoolean(bool condition)536 Oddball* Heap::ToBoolean(bool condition) {
537   ReadOnlyRoots roots(this);
538   return condition ? roots.true_value() : roots.false_value();
539 }
540 
HashSeed()541 uint64_t Heap::HashSeed() {
542   uint64_t seed;
543   hash_seed()->copy_out(0, reinterpret_cast<byte*>(&seed), kInt64Size);
544   DCHECK(FLAG_randomize_hashes || seed == 0);
545   return seed;
546 }
547 
NextScriptId()548 int Heap::NextScriptId() {
549   int last_id = last_script_id()->value();
550   if (last_id == Smi::kMaxValue) last_id = v8::UnboundScript::kNoScriptId;
551   last_id++;
552   set_last_script_id(Smi::FromInt(last_id));
553   return last_id;
554 }
555 
NextDebuggingId()556 int Heap::NextDebuggingId() {
557   int last_id = last_debugging_id()->value();
558   if (last_id == DebugInfo::DebuggingIdBits::kMax) {
559     last_id = DebugInfo::kNoDebuggingId;
560   }
561   last_id++;
562   set_last_debugging_id(Smi::FromInt(last_id));
563   return last_id;
564 }
565 
GetNextTemplateSerialNumber()566 int Heap::GetNextTemplateSerialNumber() {
567   int next_serial_number = next_template_serial_number()->value() + 1;
568   set_next_template_serial_number(Smi::FromInt(next_serial_number));
569   return next_serial_number;
570 }
571 
MaxNumberToStringCacheSize()572 int Heap::MaxNumberToStringCacheSize() const {
573   // Compute the size of the number string cache based on the max newspace size.
574   // The number string cache has a minimum size based on twice the initial cache
575   // size to ensure that it is bigger after being made 'full size'.
576   size_t number_string_cache_size = max_semi_space_size_ / 512;
577   number_string_cache_size =
578       Max(static_cast<size_t>(kInitialNumberStringCacheSize * 2),
579           Min<size_t>(0x4000u, number_string_cache_size));
580   // There is a string and a number per entry so the length is twice the number
581   // of entries.
582   return static_cast<int>(number_string_cache_size * 2);
583 }
AlwaysAllocateScope(Isolate * isolate)584 AlwaysAllocateScope::AlwaysAllocateScope(Isolate* isolate)
585     : heap_(isolate->heap()) {
586   heap_->always_allocate_scope_count_++;
587 }
588 
~AlwaysAllocateScope()589 AlwaysAllocateScope::~AlwaysAllocateScope() {
590   heap_->always_allocate_scope_count_--;
591 }
592 
CodeSpaceMemoryModificationScope(Heap * heap)593 CodeSpaceMemoryModificationScope::CodeSpaceMemoryModificationScope(Heap* heap)
594     : heap_(heap) {
595   if (heap_->write_protect_code_memory()) {
596     heap_->increment_code_space_memory_modification_scope_depth();
597     heap_->code_space()->SetReadAndWritable();
598     LargePage* page = heap_->lo_space()->first_page();
599     while (page != nullptr) {
600       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
601         CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
602         page->SetReadAndWritable();
603       }
604       page = page->next_page();
605     }
606   }
607 }
608 
~CodeSpaceMemoryModificationScope()609 CodeSpaceMemoryModificationScope::~CodeSpaceMemoryModificationScope() {
610   if (heap_->write_protect_code_memory()) {
611     heap_->decrement_code_space_memory_modification_scope_depth();
612     heap_->code_space()->SetReadAndExecutable();
613     LargePage* page = heap_->lo_space()->first_page();
614     while (page != nullptr) {
615       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
616         CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
617         page->SetReadAndExecutable();
618       }
619       page = page->next_page();
620     }
621   }
622 }
623 
624 CodePageCollectionMemoryModificationScope::
CodePageCollectionMemoryModificationScope(Heap * heap)625     CodePageCollectionMemoryModificationScope(Heap* heap)
626     : heap_(heap) {
627   if (heap_->write_protect_code_memory() &&
628       !heap_->code_space_memory_modification_scope_depth()) {
629     heap_->EnableUnprotectedMemoryChunksRegistry();
630   }
631 }
632 
633 CodePageCollectionMemoryModificationScope::
~CodePageCollectionMemoryModificationScope()634     ~CodePageCollectionMemoryModificationScope() {
635   if (heap_->write_protect_code_memory() &&
636       !heap_->code_space_memory_modification_scope_depth()) {
637     heap_->ProtectUnprotectedMemoryChunks();
638     heap_->DisableUnprotectedMemoryChunksRegistry();
639   }
640 }
641 
CodePageMemoryModificationScope(MemoryChunk * chunk)642 CodePageMemoryModificationScope::CodePageMemoryModificationScope(
643     MemoryChunk* chunk)
644     : chunk_(chunk),
645       scope_active_(chunk_->heap()->write_protect_code_memory() &&
646                     chunk_->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
647   if (scope_active_) {
648     DCHECK(chunk_->owner()->identity() == CODE_SPACE ||
649            (chunk_->owner()->identity() == LO_SPACE &&
650             chunk_->IsFlagSet(MemoryChunk::IS_EXECUTABLE)));
651     chunk_->SetReadAndWritable();
652   }
653 }
654 
~CodePageMemoryModificationScope()655 CodePageMemoryModificationScope::~CodePageMemoryModificationScope() {
656   if (scope_active_) {
657     chunk_->SetReadAndExecutable();
658   }
659 }
660 
661 }  // namespace internal
662 }  // namespace v8
663 
664 #endif  // V8_HEAP_HEAP_INL_H_
665