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_H_ 6 #define V8_HEAP_HEAP_H_ 7 8 #include <cmath> 9 #include <map> 10 11 // Clients of this interface shouldn't depend on lots of heap internals. 12 // Do not include anything from src/heap here! 13 #include "include/v8.h" 14 #include "src/allocation.h" 15 #include "src/assert-scope.h" 16 #include "src/base/atomic-utils.h" 17 #include "src/globals.h" 18 #include "src/heap-symbols.h" 19 // TODO(mstarzinger): Two more includes to kill! 20 #include "src/heap/spaces.h" 21 #include "src/heap/store-buffer.h" 22 #include "src/list.h" 23 24 namespace v8 { 25 namespace internal { 26 27 using v8::MemoryPressureLevel; 28 29 // Defines all the roots in Heap. 30 #define STRONG_ROOT_LIST(V) \ 31 /* Cluster the most popular ones in a few cache lines here at the top. */ \ 32 /* The first 32 entries are most often used in the startup snapshot and */ \ 33 /* can use a shorter representation in the serialization format. */ \ 34 V(Map, free_space_map, FreeSpaceMap) \ 35 V(Map, one_pointer_filler_map, OnePointerFillerMap) \ 36 V(Map, two_pointer_filler_map, TwoPointerFillerMap) \ 37 V(Oddball, uninitialized_value, UninitializedValue) \ 38 V(Oddball, undefined_value, UndefinedValue) \ 39 V(Oddball, the_hole_value, TheHoleValue) \ 40 V(Oddball, null_value, NullValue) \ 41 V(Oddball, true_value, TrueValue) \ 42 V(Oddball, false_value, FalseValue) \ 43 V(String, empty_string, empty_string) \ 44 V(Map, meta_map, MetaMap) \ 45 V(Map, byte_array_map, ByteArrayMap) \ 46 V(Map, fixed_array_map, FixedArrayMap) \ 47 V(Map, fixed_cow_array_map, FixedCOWArrayMap) \ 48 V(Map, hash_table_map, HashTableMap) \ 49 V(Map, symbol_map, SymbolMap) \ 50 V(Map, one_byte_string_map, OneByteStringMap) \ 51 V(Map, one_byte_internalized_string_map, OneByteInternalizedStringMap) \ 52 V(Map, scope_info_map, ScopeInfoMap) \ 53 V(Map, shared_function_info_map, SharedFunctionInfoMap) \ 54 V(Map, code_map, CodeMap) \ 55 V(Map, function_context_map, FunctionContextMap) \ 56 V(Map, cell_map, CellMap) \ 57 V(Map, weak_cell_map, WeakCellMap) \ 58 V(Map, global_property_cell_map, GlobalPropertyCellMap) \ 59 V(Map, foreign_map, ForeignMap) \ 60 V(Map, heap_number_map, HeapNumberMap) \ 61 V(Map, transition_array_map, TransitionArrayMap) \ 62 V(FixedArray, empty_literals_array, EmptyLiteralsArray) \ 63 V(FixedArray, empty_fixed_array, EmptyFixedArray) \ 64 V(FixedArray, cleared_optimized_code_map, ClearedOptimizedCodeMap) \ 65 V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray) \ 66 /* Entries beyond the first 32 */ \ 67 /* The roots above this line should be boring from a GC point of view. */ \ 68 /* This means they are never in new space and never on a page that is */ \ 69 /* being compacted. */ \ 70 /* Oddballs */ \ 71 V(Oddball, no_interceptor_result_sentinel, NoInterceptorResultSentinel) \ 72 V(Oddball, arguments_marker, ArgumentsMarker) \ 73 V(Oddball, exception, Exception) \ 74 V(Oddball, termination_exception, TerminationException) \ 75 V(Oddball, optimized_out, OptimizedOut) \ 76 V(Oddball, stale_register, StaleRegister) \ 77 /* Context maps */ \ 78 V(Map, native_context_map, NativeContextMap) \ 79 V(Map, module_context_map, ModuleContextMap) \ 80 V(Map, script_context_map, ScriptContextMap) \ 81 V(Map, block_context_map, BlockContextMap) \ 82 V(Map, catch_context_map, CatchContextMap) \ 83 V(Map, with_context_map, WithContextMap) \ 84 V(Map, debug_evaluate_context_map, DebugEvaluateContextMap) \ 85 V(Map, script_context_table_map, ScriptContextTableMap) \ 86 /* Maps */ \ 87 V(Map, fixed_double_array_map, FixedDoubleArrayMap) \ 88 V(Map, mutable_heap_number_map, MutableHeapNumberMap) \ 89 V(Map, ordered_hash_table_map, OrderedHashTableMap) \ 90 V(Map, sloppy_arguments_elements_map, SloppyArgumentsElementsMap) \ 91 V(Map, message_object_map, JSMessageObjectMap) \ 92 V(Map, neander_map, NeanderMap) \ 93 V(Map, external_map, ExternalMap) \ 94 V(Map, bytecode_array_map, BytecodeArrayMap) \ 95 /* String maps */ \ 96 V(Map, native_source_string_map, NativeSourceStringMap) \ 97 V(Map, string_map, StringMap) \ 98 V(Map, cons_one_byte_string_map, ConsOneByteStringMap) \ 99 V(Map, cons_string_map, ConsStringMap) \ 100 V(Map, sliced_string_map, SlicedStringMap) \ 101 V(Map, sliced_one_byte_string_map, SlicedOneByteStringMap) \ 102 V(Map, external_string_map, ExternalStringMap) \ 103 V(Map, external_string_with_one_byte_data_map, \ 104 ExternalStringWithOneByteDataMap) \ 105 V(Map, external_one_byte_string_map, ExternalOneByteStringMap) \ 106 V(Map, short_external_string_map, ShortExternalStringMap) \ 107 V(Map, short_external_string_with_one_byte_data_map, \ 108 ShortExternalStringWithOneByteDataMap) \ 109 V(Map, internalized_string_map, InternalizedStringMap) \ 110 V(Map, external_internalized_string_map, ExternalInternalizedStringMap) \ 111 V(Map, external_internalized_string_with_one_byte_data_map, \ 112 ExternalInternalizedStringWithOneByteDataMap) \ 113 V(Map, external_one_byte_internalized_string_map, \ 114 ExternalOneByteInternalizedStringMap) \ 115 V(Map, short_external_internalized_string_map, \ 116 ShortExternalInternalizedStringMap) \ 117 V(Map, short_external_internalized_string_with_one_byte_data_map, \ 118 ShortExternalInternalizedStringWithOneByteDataMap) \ 119 V(Map, short_external_one_byte_internalized_string_map, \ 120 ShortExternalOneByteInternalizedStringMap) \ 121 V(Map, short_external_one_byte_string_map, ShortExternalOneByteStringMap) \ 122 /* Array element maps */ \ 123 V(Map, fixed_uint8_array_map, FixedUint8ArrayMap) \ 124 V(Map, fixed_int8_array_map, FixedInt8ArrayMap) \ 125 V(Map, fixed_uint16_array_map, FixedUint16ArrayMap) \ 126 V(Map, fixed_int16_array_map, FixedInt16ArrayMap) \ 127 V(Map, fixed_uint32_array_map, FixedUint32ArrayMap) \ 128 V(Map, fixed_int32_array_map, FixedInt32ArrayMap) \ 129 V(Map, fixed_float32_array_map, FixedFloat32ArrayMap) \ 130 V(Map, fixed_float64_array_map, FixedFloat64ArrayMap) \ 131 V(Map, fixed_uint8_clamped_array_map, FixedUint8ClampedArrayMap) \ 132 V(Map, float32x4_map, Float32x4Map) \ 133 V(Map, int32x4_map, Int32x4Map) \ 134 V(Map, uint32x4_map, Uint32x4Map) \ 135 V(Map, bool32x4_map, Bool32x4Map) \ 136 V(Map, int16x8_map, Int16x8Map) \ 137 V(Map, uint16x8_map, Uint16x8Map) \ 138 V(Map, bool16x8_map, Bool16x8Map) \ 139 V(Map, int8x16_map, Int8x16Map) \ 140 V(Map, uint8x16_map, Uint8x16Map) \ 141 V(Map, bool8x16_map, Bool8x16Map) \ 142 /* Canonical empty values */ \ 143 V(ByteArray, empty_byte_array, EmptyByteArray) \ 144 V(FixedTypedArrayBase, empty_fixed_uint8_array, EmptyFixedUint8Array) \ 145 V(FixedTypedArrayBase, empty_fixed_int8_array, EmptyFixedInt8Array) \ 146 V(FixedTypedArrayBase, empty_fixed_uint16_array, EmptyFixedUint16Array) \ 147 V(FixedTypedArrayBase, empty_fixed_int16_array, EmptyFixedInt16Array) \ 148 V(FixedTypedArrayBase, empty_fixed_uint32_array, EmptyFixedUint32Array) \ 149 V(FixedTypedArrayBase, empty_fixed_int32_array, EmptyFixedInt32Array) \ 150 V(FixedTypedArrayBase, empty_fixed_float32_array, EmptyFixedFloat32Array) \ 151 V(FixedTypedArrayBase, empty_fixed_float64_array, EmptyFixedFloat64Array) \ 152 V(FixedTypedArrayBase, empty_fixed_uint8_clamped_array, \ 153 EmptyFixedUint8ClampedArray) \ 154 V(Script, empty_script, EmptyScript) \ 155 V(Cell, undefined_cell, UndefinedCell) \ 156 V(FixedArray, empty_sloppy_arguments_elements, EmptySloppyArgumentsElements) \ 157 V(SeededNumberDictionary, empty_slow_element_dictionary, \ 158 EmptySlowElementDictionary) \ 159 V(TypeFeedbackVector, dummy_vector, DummyVector) \ 160 V(PropertyCell, empty_property_cell, EmptyPropertyCell) \ 161 V(WeakCell, empty_weak_cell, EmptyWeakCell) \ 162 /* Protectors */ \ 163 V(PropertyCell, array_protector, ArrayProtector) \ 164 V(Cell, is_concat_spreadable_protector, IsConcatSpreadableProtector) \ 165 V(PropertyCell, has_instance_protector, HasInstanceProtector) \ 166 V(Cell, species_protector, SpeciesProtector) \ 167 /* Special numbers */ \ 168 V(HeapNumber, nan_value, NanValue) \ 169 V(HeapNumber, infinity_value, InfinityValue) \ 170 V(HeapNumber, minus_zero_value, MinusZeroValue) \ 171 V(HeapNumber, minus_infinity_value, MinusInfinityValue) \ 172 /* Caches */ \ 173 V(FixedArray, number_string_cache, NumberStringCache) \ 174 V(FixedArray, single_character_string_cache, SingleCharacterStringCache) \ 175 V(FixedArray, string_split_cache, StringSplitCache) \ 176 V(FixedArray, regexp_multiple_cache, RegExpMultipleCache) \ 177 V(Object, instanceof_cache_function, InstanceofCacheFunction) \ 178 V(Object, instanceof_cache_map, InstanceofCacheMap) \ 179 V(Object, instanceof_cache_answer, InstanceofCacheAnswer) \ 180 V(FixedArray, natives_source_cache, NativesSourceCache) \ 181 V(FixedArray, experimental_natives_source_cache, \ 182 ExperimentalNativesSourceCache) \ 183 V(FixedArray, extra_natives_source_cache, ExtraNativesSourceCache) \ 184 V(FixedArray, experimental_extra_natives_source_cache, \ 185 ExperimentalExtraNativesSourceCache) \ 186 /* Lists and dictionaries */ \ 187 V(NameDictionary, intrinsic_function_names, IntrinsicFunctionNames) \ 188 V(NameDictionary, empty_properties_dictionary, EmptyPropertiesDictionary) \ 189 V(Object, symbol_registry, SymbolRegistry) \ 190 V(Object, script_list, ScriptList) \ 191 V(UnseededNumberDictionary, code_stubs, CodeStubs) \ 192 V(FixedArray, materialized_objects, MaterializedObjects) \ 193 V(FixedArray, microtask_queue, MicrotaskQueue) \ 194 V(FixedArray, detached_contexts, DetachedContexts) \ 195 V(ArrayList, retained_maps, RetainedMaps) \ 196 V(WeakHashTable, weak_object_to_code_table, WeakObjectToCodeTable) \ 197 V(Object, weak_stack_trace_list, WeakStackTraceList) \ 198 V(Object, noscript_shared_function_infos, NoScriptSharedFunctionInfos) \ 199 V(FixedArray, serialized_templates, SerializedTemplates) \ 200 /* Configured values */ \ 201 V(JSObject, message_listeners, MessageListeners) \ 202 V(Code, js_entry_code, JsEntryCode) \ 203 V(Code, js_construct_entry_code, JsConstructEntryCode) \ 204 /* Oddball maps */ \ 205 V(Map, undefined_map, UndefinedMap) \ 206 V(Map, the_hole_map, TheHoleMap) \ 207 V(Map, null_map, NullMap) \ 208 V(Map, boolean_map, BooleanMap) \ 209 V(Map, uninitialized_map, UninitializedMap) \ 210 V(Map, arguments_marker_map, ArgumentsMarkerMap) \ 211 V(Map, no_interceptor_result_sentinel_map, NoInterceptorResultSentinelMap) \ 212 V(Map, exception_map, ExceptionMap) \ 213 V(Map, termination_exception_map, TerminationExceptionMap) \ 214 V(Map, optimized_out_map, OptimizedOutMap) \ 215 V(Map, stale_register_map, StaleRegisterMap) 216 217 // Entries in this list are limited to Smis and are not visited during GC. 218 #define SMI_ROOT_LIST(V) \ 219 V(Smi, stack_limit, StackLimit) \ 220 V(Smi, real_stack_limit, RealStackLimit) \ 221 V(Smi, last_script_id, LastScriptId) \ 222 V(Smi, hash_seed, HashSeed) \ 223 /* To distinguish the function templates, so that we can find them in the */ \ 224 /* function cache of the native context. */ \ 225 V(Smi, next_template_serial_number, NextTemplateSerialNumber) \ 226 V(Smi, arguments_adaptor_deopt_pc_offset, ArgumentsAdaptorDeoptPCOffset) \ 227 V(Smi, construct_stub_deopt_pc_offset, ConstructStubDeoptPCOffset) \ 228 V(Smi, getter_stub_deopt_pc_offset, GetterStubDeoptPCOffset) \ 229 V(Smi, setter_stub_deopt_pc_offset, SetterStubDeoptPCOffset) \ 230 V(Smi, interpreter_entry_return_pc_offset, InterpreterEntryReturnPCOffset) 231 232 #define ROOT_LIST(V) \ 233 STRONG_ROOT_LIST(V) \ 234 SMI_ROOT_LIST(V) \ 235 V(StringTable, string_table, StringTable) 236 237 238 // Heap roots that are known to be immortal immovable, for which we can safely 239 // skip write barriers. This list is not complete and has omissions. 240 #define IMMORTAL_IMMOVABLE_ROOT_LIST(V) \ 241 V(ByteArrayMap) \ 242 V(BytecodeArrayMap) \ 243 V(FreeSpaceMap) \ 244 V(OnePointerFillerMap) \ 245 V(TwoPointerFillerMap) \ 246 V(UndefinedValue) \ 247 V(TheHoleValue) \ 248 V(NullValue) \ 249 V(TrueValue) \ 250 V(FalseValue) \ 251 V(UninitializedValue) \ 252 V(CellMap) \ 253 V(GlobalPropertyCellMap) \ 254 V(SharedFunctionInfoMap) \ 255 V(MetaMap) \ 256 V(HeapNumberMap) \ 257 V(MutableHeapNumberMap) \ 258 V(Float32x4Map) \ 259 V(Int32x4Map) \ 260 V(Uint32x4Map) \ 261 V(Bool32x4Map) \ 262 V(Int16x8Map) \ 263 V(Uint16x8Map) \ 264 V(Bool16x8Map) \ 265 V(Int8x16Map) \ 266 V(Uint8x16Map) \ 267 V(Bool8x16Map) \ 268 V(NativeContextMap) \ 269 V(FixedArrayMap) \ 270 V(CodeMap) \ 271 V(ScopeInfoMap) \ 272 V(FixedCOWArrayMap) \ 273 V(FixedDoubleArrayMap) \ 274 V(WeakCellMap) \ 275 V(TransitionArrayMap) \ 276 V(NoInterceptorResultSentinel) \ 277 V(HashTableMap) \ 278 V(OrderedHashTableMap) \ 279 V(EmptyFixedArray) \ 280 V(EmptyByteArray) \ 281 V(EmptyDescriptorArray) \ 282 V(ArgumentsMarker) \ 283 V(SymbolMap) \ 284 V(SloppyArgumentsElementsMap) \ 285 V(FunctionContextMap) \ 286 V(CatchContextMap) \ 287 V(WithContextMap) \ 288 V(BlockContextMap) \ 289 V(ModuleContextMap) \ 290 V(ScriptContextMap) \ 291 V(UndefinedMap) \ 292 V(TheHoleMap) \ 293 V(NullMap) \ 294 V(BooleanMap) \ 295 V(UninitializedMap) \ 296 V(ArgumentsMarkerMap) \ 297 V(JSMessageObjectMap) \ 298 V(ForeignMap) \ 299 V(NeanderMap) \ 300 V(NanValue) \ 301 V(InfinityValue) \ 302 V(MinusZeroValue) \ 303 V(MinusInfinityValue) \ 304 V(EmptyWeakCell) \ 305 V(empty_string) \ 306 PRIVATE_SYMBOL_LIST(V) 307 308 // Forward declarations. 309 class AllocationObserver; 310 class ArrayBufferTracker; 311 class GCIdleTimeAction; 312 class GCIdleTimeHandler; 313 class GCIdleTimeHeapState; 314 class GCTracer; 315 class HeapObjectsFilter; 316 class HeapStats; 317 class HistogramTimer; 318 class Isolate; 319 class MemoryReducer; 320 class ObjectStats; 321 class Scavenger; 322 class ScavengeJob; 323 class WeakObjectRetainer; 324 325 enum PromotionMode { PROMOTE_MARKED, DEFAULT_PROMOTION }; 326 327 typedef void (*ObjectSlotCallback)(HeapObject** from, HeapObject* to); 328 329 // A queue of objects promoted during scavenge. Each object is accompanied 330 // by it's size to avoid dereferencing a map pointer for scanning. 331 // The last page in to-space is used for the promotion queue. On conflict 332 // during scavenge, the promotion queue is allocated externally and all 333 // entries are copied to the external queue. 334 class PromotionQueue { 335 public: 336 explicit PromotionQueue(Heap* heap) 337 : front_(NULL), 338 rear_(NULL), 339 limit_(NULL), 340 emergency_stack_(0), 341 heap_(heap) {} 342 343 void Initialize(); 344 345 void Destroy() { 346 DCHECK(is_empty()); 347 delete emergency_stack_; 348 emergency_stack_ = NULL; 349 } 350 351 Page* GetHeadPage() { 352 return Page::FromAllocationAreaAddress(reinterpret_cast<Address>(rear_)); 353 } 354 355 void SetNewLimit(Address limit) { 356 // If we are already using an emergency stack, we can ignore it. 357 if (emergency_stack_) return; 358 359 // If the limit is not on the same page, we can ignore it. 360 if (Page::FromAllocationAreaAddress(limit) != GetHeadPage()) return; 361 362 limit_ = reinterpret_cast<struct Entry*>(limit); 363 364 if (limit_ <= rear_) { 365 return; 366 } 367 368 RelocateQueueHead(); 369 } 370 371 bool IsBelowPromotionQueue(Address to_space_top) { 372 // If an emergency stack is used, the to-space address cannot interfere 373 // with the promotion queue. 374 if (emergency_stack_) return true; 375 376 // If the given to-space top pointer and the head of the promotion queue 377 // are not on the same page, then the to-space objects are below the 378 // promotion queue. 379 if (GetHeadPage() != Page::FromAddress(to_space_top)) { 380 return true; 381 } 382 // If the to space top pointer is smaller or equal than the promotion 383 // queue head, then the to-space objects are below the promotion queue. 384 return reinterpret_cast<struct Entry*>(to_space_top) <= rear_; 385 } 386 387 bool is_empty() { 388 return (front_ == rear_) && 389 (emergency_stack_ == NULL || emergency_stack_->length() == 0); 390 } 391 392 inline void insert(HeapObject* target, int32_t size, bool was_marked_black); 393 394 void remove(HeapObject** target, int32_t* size, bool* was_marked_black) { 395 DCHECK(!is_empty()); 396 if (front_ == rear_) { 397 Entry e = emergency_stack_->RemoveLast(); 398 *target = e.obj_; 399 *size = e.size_; 400 *was_marked_black = e.was_marked_black_; 401 return; 402 } 403 404 struct Entry* entry = reinterpret_cast<struct Entry*>(--front_); 405 *target = entry->obj_; 406 *size = entry->size_; 407 *was_marked_black = entry->was_marked_black_; 408 409 // Assert no underflow. 410 SemiSpace::AssertValidRange(reinterpret_cast<Address>(rear_), 411 reinterpret_cast<Address>(front_)); 412 } 413 414 private: 415 struct Entry { 416 Entry(HeapObject* obj, int32_t size, bool was_marked_black) 417 : obj_(obj), size_(size), was_marked_black_(was_marked_black) {} 418 419 HeapObject* obj_; 420 int32_t size_ : 31; 421 bool was_marked_black_ : 1; 422 }; 423 424 void RelocateQueueHead(); 425 426 // The front of the queue is higher in the memory page chain than the rear. 427 struct Entry* front_; 428 struct Entry* rear_; 429 struct Entry* limit_; 430 431 List<Entry>* emergency_stack_; 432 433 Heap* heap_; 434 435 DISALLOW_COPY_AND_ASSIGN(PromotionQueue); 436 }; 437 438 439 enum ArrayStorageAllocationMode { 440 DONT_INITIALIZE_ARRAY_ELEMENTS, 441 INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE 442 }; 443 444 enum class ClearRecordedSlots { kYes, kNo }; 445 446 class Heap { 447 public: 448 // Declare all the root indices. This defines the root list order. 449 enum RootListIndex { 450 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex, 451 STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION) 452 #undef ROOT_INDEX_DECLARATION 453 454 #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex, 455 INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION) 456 #undef STRING_DECLARATION 457 458 #define SYMBOL_INDEX_DECLARATION(name) k##name##RootIndex, 459 PRIVATE_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION) 460 #undef SYMBOL_INDEX_DECLARATION 461 462 #define SYMBOL_INDEX_DECLARATION(name, description) k##name##RootIndex, 463 PUBLIC_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION) 464 WELL_KNOWN_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION) 465 #undef SYMBOL_INDEX_DECLARATION 466 467 // Utility type maps 468 #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex, 469 STRUCT_LIST(DECLARE_STRUCT_MAP) 470 #undef DECLARE_STRUCT_MAP 471 kStringTableRootIndex, 472 473 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex, 474 SMI_ROOT_LIST(ROOT_INDEX_DECLARATION) 475 #undef ROOT_INDEX_DECLARATION 476 kRootListLength, 477 kStrongRootListLength = kStringTableRootIndex, 478 kSmiRootsStart = kStringTableRootIndex + 1 479 }; 480 481 enum FindMementoMode { kForRuntime, kForGC }; 482 483 enum HeapState { NOT_IN_GC, SCAVENGE, MARK_COMPACT }; 484 485 // Indicates whether live bytes adjustment is triggered 486 // - from within the GC code before sweeping started (SEQUENTIAL_TO_SWEEPER), 487 // - or from within GC (CONCURRENT_TO_SWEEPER), 488 // - or mutator code (CONCURRENT_TO_SWEEPER). 489 enum InvocationMode { SEQUENTIAL_TO_SWEEPER, CONCURRENT_TO_SWEEPER }; 490 491 enum UpdateAllocationSiteMode { kGlobal, kCached }; 492 493 // Taking this lock prevents the GC from entering a phase that relocates 494 // object references. 495 class RelocationLock { 496 public: 497 explicit RelocationLock(Heap* heap) : heap_(heap) { 498 heap_->relocation_mutex_.Lock(); 499 } 500 501 ~RelocationLock() { heap_->relocation_mutex_.Unlock(); } 502 503 private: 504 Heap* heap_; 505 }; 506 507 // Support for partial snapshots. After calling this we have a linear 508 // space to write objects in each space. 509 struct Chunk { 510 uint32_t size; 511 Address start; 512 Address end; 513 }; 514 typedef List<Chunk> Reservation; 515 516 static const intptr_t kMinimumOldGenerationAllocationLimit = 517 8 * (Page::kPageSize > MB ? Page::kPageSize : MB); 518 519 static const int kInitalOldGenerationLimitFactor = 2; 520 521 #if V8_OS_ANDROID 522 // Don't apply pointer multiplier on Android since it has no swap space and 523 // should instead adapt it's heap size based on available physical memory. 524 static const int kPointerMultiplier = 1; 525 #else 526 static const int kPointerMultiplier = i::kPointerSize / 4; 527 #endif 528 529 // The new space size has to be a power of 2. Sizes are in MB. 530 static const int kMaxSemiSpaceSizeLowMemoryDevice = 1 * kPointerMultiplier; 531 static const int kMaxSemiSpaceSizeMediumMemoryDevice = 4 * kPointerMultiplier; 532 static const int kMaxSemiSpaceSizeHighMemoryDevice = 8 * kPointerMultiplier; 533 static const int kMaxSemiSpaceSizeHugeMemoryDevice = 8 * kPointerMultiplier; 534 535 // The old space size has to be a multiple of Page::kPageSize. 536 // Sizes are in MB. 537 static const int kMaxOldSpaceSizeLowMemoryDevice = 128 * kPointerMultiplier; 538 static const int kMaxOldSpaceSizeMediumMemoryDevice = 539 256 * kPointerMultiplier; 540 static const int kMaxOldSpaceSizeHighMemoryDevice = 512 * kPointerMultiplier; 541 static const int kMaxOldSpaceSizeHugeMemoryDevice = 700 * kPointerMultiplier; 542 543 // The executable size has to be a multiple of Page::kPageSize. 544 // Sizes are in MB. 545 static const int kMaxExecutableSizeLowMemoryDevice = 96 * kPointerMultiplier; 546 static const int kMaxExecutableSizeMediumMemoryDevice = 547 192 * kPointerMultiplier; 548 static const int kMaxExecutableSizeHighMemoryDevice = 549 256 * kPointerMultiplier; 550 static const int kMaxExecutableSizeHugeMemoryDevice = 551 256 * kPointerMultiplier; 552 553 static const int kTraceRingBufferSize = 512; 554 static const int kStacktraceBufferSize = 512; 555 556 static const double kMinHeapGrowingFactor; 557 static const double kMaxHeapGrowingFactor; 558 static const double kMaxHeapGrowingFactorMemoryConstrained; 559 static const double kMaxHeapGrowingFactorIdle; 560 static const double kTargetMutatorUtilization; 561 562 static const int kNoGCFlags = 0; 563 static const int kReduceMemoryFootprintMask = 1; 564 static const int kAbortIncrementalMarkingMask = 2; 565 static const int kFinalizeIncrementalMarkingMask = 4; 566 567 // Making the heap iterable requires us to abort incremental marking. 568 static const int kMakeHeapIterableMask = kAbortIncrementalMarkingMask; 569 570 // The roots that have an index less than this are always in old space. 571 static const int kOldSpaceRoots = 0x20; 572 573 // The minimum size of a HeapObject on the heap. 574 static const int kMinObjectSizeInWords = 2; 575 576 STATIC_ASSERT(kUndefinedValueRootIndex == 577 Internals::kUndefinedValueRootIndex); 578 STATIC_ASSERT(kTheHoleValueRootIndex == Internals::kTheHoleValueRootIndex); 579 STATIC_ASSERT(kNullValueRootIndex == Internals::kNullValueRootIndex); 580 STATIC_ASSERT(kTrueValueRootIndex == Internals::kTrueValueRootIndex); 581 STATIC_ASSERT(kFalseValueRootIndex == Internals::kFalseValueRootIndex); 582 STATIC_ASSERT(kempty_stringRootIndex == Internals::kEmptyStringRootIndex); 583 584 // Calculates the maximum amount of filler that could be required by the 585 // given alignment. 586 static int GetMaximumFillToAlign(AllocationAlignment alignment); 587 // Calculates the actual amount of filler required for a given address at the 588 // given alignment. 589 static int GetFillToAlign(Address address, AllocationAlignment alignment); 590 591 template <typename T> 592 static inline bool IsOneByte(T t, int chars); 593 594 static void FatalProcessOutOfMemory(const char* location, 595 bool is_heap_oom = false); 596 597 static bool RootIsImmortalImmovable(int root_index); 598 599 // Checks whether the space is valid. 600 static bool IsValidAllocationSpace(AllocationSpace space); 601 602 // Generated code can embed direct references to non-writable roots if 603 // they are in new space. 604 static bool RootCanBeWrittenAfterInitialization(RootListIndex root_index); 605 606 // Zapping is needed for verify heap, and always done in debug builds. 607 static inline bool ShouldZapGarbage() { 608 #ifdef DEBUG 609 return true; 610 #else 611 #ifdef VERIFY_HEAP 612 return FLAG_verify_heap; 613 #else 614 return false; 615 #endif 616 #endif 617 } 618 619 static double HeapGrowingFactor(double gc_speed, double mutator_speed); 620 621 // Copy block of memory from src to dst. Size of block should be aligned 622 // by pointer size. 623 static inline void CopyBlock(Address dst, Address src, int byte_size); 624 625 // Determines a static visitor id based on the given {map} that can then be 626 // stored on the map to facilitate fast dispatch for {StaticVisitorBase}. 627 static int GetStaticVisitorIdForMap(Map* map); 628 629 // We cannot avoid stale handles to left-trimmed objects, but can only make 630 // sure all handles still needed are updated. Filter out a stale pointer 631 // and clear the slot to allow post processing of handles (needed because 632 // the sweeper might actually free the underlying page). 633 inline bool PurgeLeftTrimmedObject(Object** object); 634 635 // Notifies the heap that is ok to start marking or other activities that 636 // should not happen during deserialization. 637 void NotifyDeserializationComplete(); 638 639 intptr_t old_generation_allocation_limit() const { 640 return old_generation_allocation_limit_; 641 } 642 643 bool always_allocate() { return always_allocate_scope_count_.Value() != 0; } 644 645 Address* NewSpaceAllocationTopAddress() { 646 return new_space_.allocation_top_address(); 647 } 648 Address* NewSpaceAllocationLimitAddress() { 649 return new_space_.allocation_limit_address(); 650 } 651 652 Address* OldSpaceAllocationTopAddress() { 653 return old_space_->allocation_top_address(); 654 } 655 Address* OldSpaceAllocationLimitAddress() { 656 return old_space_->allocation_limit_address(); 657 } 658 659 bool CanExpandOldGeneration(int size) { 660 if (force_oom_) return false; 661 return (OldGenerationCapacity() + size) < MaxOldGenerationSize(); 662 } 663 664 // Clear the Instanceof cache (used when a prototype changes). 665 inline void ClearInstanceofCache(); 666 667 // FreeSpace objects have a null map after deserialization. Update the map. 668 void RepairFreeListsAfterDeserialization(); 669 670 // Move len elements within a given array from src_index index to dst_index 671 // index. 672 void MoveElements(FixedArray* array, int dst_index, int src_index, int len); 673 674 // Initialize a filler object to keep the ability to iterate over the heap 675 // when introducing gaps within pages. If slots could have been recorded in 676 // the freed area, then pass ClearRecordedSlots::kYes as the mode. Otherwise, 677 // pass ClearRecordedSlots::kNo. 678 void CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots mode); 679 680 bool CanMoveObjectStart(HeapObject* object); 681 682 // Maintain consistency of live bytes during incremental marking. 683 void AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode); 684 685 // Trim the given array from the left. Note that this relocates the object 686 // start and hence is only valid if there is only a single reference to it. 687 FixedArrayBase* LeftTrimFixedArray(FixedArrayBase* obj, int elements_to_trim); 688 689 // Trim the given array from the right. 690 template<Heap::InvocationMode mode> 691 void RightTrimFixedArray(FixedArrayBase* obj, int elements_to_trim); 692 693 // Converts the given boolean condition to JavaScript boolean value. 694 inline Oddball* ToBoolean(bool condition); 695 696 // Check whether the heap is currently iterable. 697 bool IsHeapIterable(); 698 699 // Notify the heap that a context has been disposed. 700 int NotifyContextDisposed(bool dependant_context); 701 702 void set_native_contexts_list(Object* object) { 703 native_contexts_list_ = object; 704 } 705 Object* native_contexts_list() const { return native_contexts_list_; } 706 707 void set_allocation_sites_list(Object* object) { 708 allocation_sites_list_ = object; 709 } 710 Object* allocation_sites_list() { return allocation_sites_list_; } 711 712 // Used in CreateAllocationSiteStub and the (de)serializer. 713 Object** allocation_sites_list_address() { return &allocation_sites_list_; } 714 715 void set_encountered_weak_collections(Object* weak_collection) { 716 encountered_weak_collections_ = weak_collection; 717 } 718 Object* encountered_weak_collections() const { 719 return encountered_weak_collections_; 720 } 721 722 void set_encountered_weak_cells(Object* weak_cell) { 723 encountered_weak_cells_ = weak_cell; 724 } 725 Object* encountered_weak_cells() const { return encountered_weak_cells_; } 726 727 void set_encountered_transition_arrays(Object* transition_array) { 728 encountered_transition_arrays_ = transition_array; 729 } 730 Object* encountered_transition_arrays() const { 731 return encountered_transition_arrays_; 732 } 733 734 // Number of mark-sweeps. 735 int ms_count() const { return ms_count_; } 736 737 // Checks whether the given object is allowed to be migrated from it's 738 // current space into the given destination space. Used for debugging. 739 inline bool AllowedToBeMigrated(HeapObject* object, AllocationSpace dest); 740 741 void CheckHandleCount(); 742 743 // Number of "runtime allocations" done so far. 744 uint32_t allocations_count() { return allocations_count_; } 745 746 // Print short heap statistics. 747 void PrintShortHeapStatistics(); 748 749 inline HeapState gc_state() { return gc_state_; } 750 751 inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; } 752 753 // If an object has an AllocationMemento trailing it, return it, otherwise 754 // return NULL; 755 template <FindMementoMode mode> 756 inline AllocationMemento* FindAllocationMemento(HeapObject* object); 757 758 // Returns false if not able to reserve. 759 bool ReserveSpace(Reservation* reservations); 760 761 void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer); 762 763 bool UsingEmbedderHeapTracer(); 764 765 void TracePossibleWrapper(JSObject* js_object); 766 767 void RegisterExternallyReferencedObject(Object** object); 768 769 // 770 // Support for the API. 771 // 772 773 void CreateApiObjects(); 774 775 // Implements the corresponding V8 API function. 776 bool IdleNotification(double deadline_in_seconds); 777 bool IdleNotification(int idle_time_in_ms); 778 779 void MemoryPressureNotification(MemoryPressureLevel level, 780 bool is_isolate_locked); 781 void CheckMemoryPressure(); 782 783 double MonotonicallyIncreasingTimeInMs(); 784 785 void RecordStats(HeapStats* stats, bool take_snapshot = false); 786 787 // Check new space expansion criteria and expand semispaces if it was hit. 788 void CheckNewSpaceExpansionCriteria(); 789 790 inline bool HeapIsFullEnoughToStartIncrementalMarking(intptr_t limit) { 791 if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true; 792 793 intptr_t adjusted_allocation_limit = limit - new_space_.Capacity(); 794 795 if (PromotedTotalSize() >= adjusted_allocation_limit) return true; 796 797 if (HighMemoryPressure()) return true; 798 799 return false; 800 } 801 802 void VisitExternalResources(v8::ExternalResourceVisitor* visitor); 803 804 // An object should be promoted if the object has survived a 805 // scavenge operation. 806 template <PromotionMode promotion_mode> 807 inline bool ShouldBePromoted(Address old_address, int object_size); 808 809 inline PromotionMode CurrentPromotionMode(); 810 811 void ClearNormalizedMapCaches(); 812 813 void IncrementDeferredCount(v8::Isolate::UseCounterFeature feature); 814 815 inline bool OldGenerationAllocationLimitReached(); 816 817 // Completely clear the Instanceof cache (to stop it keeping objects alive 818 // around a GC). 819 inline void CompletelyClearInstanceofCache(); 820 821 inline uint32_t HashSeed(); 822 823 inline int NextScriptId(); 824 825 inline void SetArgumentsAdaptorDeoptPCOffset(int pc_offset); 826 inline void SetConstructStubDeoptPCOffset(int pc_offset); 827 inline void SetGetterStubDeoptPCOffset(int pc_offset); 828 inline void SetSetterStubDeoptPCOffset(int pc_offset); 829 inline void SetInterpreterEntryReturnPCOffset(int pc_offset); 830 inline int GetNextTemplateSerialNumber(); 831 832 inline void SetSerializedTemplates(FixedArray* templates); 833 834 // For post mortem debugging. 835 void RememberUnmappedPage(Address page, bool compacted); 836 837 // Global inline caching age: it is incremented on some GCs after context 838 // disposal. We use it to flush inline caches. 839 int global_ic_age() { return global_ic_age_; } 840 841 void AgeInlineCaches() { 842 global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax; 843 } 844 845 int64_t external_memory() { return external_memory_; } 846 void update_external_memory(int64_t delta) { external_memory_ += delta; } 847 848 void update_external_memory_concurrently_freed(intptr_t freed) { 849 external_memory_concurrently_freed_.Increment(freed); 850 } 851 852 void account_external_memory_concurrently_freed() { 853 external_memory_ -= external_memory_concurrently_freed_.Value(); 854 external_memory_concurrently_freed_.SetValue(0); 855 } 856 857 void DeoptMarkedAllocationSites(); 858 859 bool DeoptMaybeTenuredAllocationSites() { 860 return new_space_.IsAtMaximumCapacity() && maximum_size_scavenges_ == 0; 861 } 862 863 void AddWeakObjectToCodeDependency(Handle<HeapObject> obj, 864 Handle<DependentCode> dep); 865 866 DependentCode* LookupWeakObjectToCodeDependency(Handle<HeapObject> obj); 867 868 void CompactWeakFixedArrays(); 869 870 void AddRetainedMap(Handle<Map> map); 871 872 // This event is triggered after successful allocation of a new object made 873 // by runtime. Allocations of target space for object evacuation do not 874 // trigger the event. In order to track ALL allocations one must turn off 875 // FLAG_inline_new and FLAG_use_allocation_folding. 876 inline void OnAllocationEvent(HeapObject* object, int size_in_bytes); 877 878 // This event is triggered after object is moved to a new place. 879 inline void OnMoveEvent(HeapObject* target, HeapObject* source, 880 int size_in_bytes); 881 882 bool deserialization_complete() const { return deserialization_complete_; } 883 884 bool HasLowAllocationRate(); 885 bool HasHighFragmentation(); 886 bool HasHighFragmentation(intptr_t used, intptr_t committed); 887 888 void SetOptimizeForLatency() { optimize_for_memory_usage_ = false; } 889 void SetOptimizeForMemoryUsage(); 890 bool ShouldOptimizeForMemoryUsage() { 891 return optimize_for_memory_usage_ || HighMemoryPressure(); 892 } 893 bool HighMemoryPressure() { 894 return memory_pressure_level_.Value() != MemoryPressureLevel::kNone; 895 } 896 897 // =========================================================================== 898 // Initialization. =========================================================== 899 // =========================================================================== 900 901 // Configure heap size in MB before setup. Return false if the heap has been 902 // set up already. 903 bool ConfigureHeap(int max_semi_space_size, int max_old_space_size, 904 int max_executable_size, size_t code_range_size); 905 bool ConfigureHeapDefault(); 906 907 // Prepares the heap, setting up memory areas that are needed in the isolate 908 // without actually creating any objects. 909 bool SetUp(); 910 911 // Bootstraps the object heap with the core set of objects required to run. 912 // Returns whether it succeeded. 913 bool CreateHeapObjects(); 914 915 // Destroys all memory allocated by the heap. 916 void TearDown(); 917 918 // Returns whether SetUp has been called. 919 bool HasBeenSetUp(); 920 921 // =========================================================================== 922 // Getters for spaces. ======================================================= 923 // =========================================================================== 924 925 Address NewSpaceTop() { return new_space_.top(); } 926 927 NewSpace* new_space() { return &new_space_; } 928 OldSpace* old_space() { return old_space_; } 929 OldSpace* code_space() { return code_space_; } 930 MapSpace* map_space() { return map_space_; } 931 LargeObjectSpace* lo_space() { return lo_space_; } 932 933 PagedSpace* paged_space(int idx) { 934 switch (idx) { 935 case OLD_SPACE: 936 return old_space(); 937 case MAP_SPACE: 938 return map_space(); 939 case CODE_SPACE: 940 return code_space(); 941 case NEW_SPACE: 942 case LO_SPACE: 943 UNREACHABLE(); 944 } 945 return NULL; 946 } 947 948 Space* space(int idx) { 949 switch (idx) { 950 case NEW_SPACE: 951 return new_space(); 952 case LO_SPACE: 953 return lo_space(); 954 default: 955 return paged_space(idx); 956 } 957 } 958 959 // Returns name of the space. 960 const char* GetSpaceName(int idx); 961 962 // =========================================================================== 963 // Getters to other components. ============================================== 964 // =========================================================================== 965 966 GCTracer* tracer() { return tracer_; } 967 968 MemoryAllocator* memory_allocator() { return memory_allocator_; } 969 970 PromotionQueue* promotion_queue() { return &promotion_queue_; } 971 972 inline Isolate* isolate(); 973 974 MarkCompactCollector* mark_compact_collector() { 975 return mark_compact_collector_; 976 } 977 978 // =========================================================================== 979 // Root set access. ========================================================== 980 // =========================================================================== 981 982 // Heap root getters. 983 #define ROOT_ACCESSOR(type, name, camel_name) inline type* name(); 984 ROOT_LIST(ROOT_ACCESSOR) 985 #undef ROOT_ACCESSOR 986 987 // Utility type maps. 988 #define STRUCT_MAP_ACCESSOR(NAME, Name, name) inline Map* name##_map(); 989 STRUCT_LIST(STRUCT_MAP_ACCESSOR) 990 #undef STRUCT_MAP_ACCESSOR 991 992 #define STRING_ACCESSOR(name, str) inline String* name(); 993 INTERNALIZED_STRING_LIST(STRING_ACCESSOR) 994 #undef STRING_ACCESSOR 995 996 #define SYMBOL_ACCESSOR(name) inline Symbol* name(); 997 PRIVATE_SYMBOL_LIST(SYMBOL_ACCESSOR) 998 #undef SYMBOL_ACCESSOR 999 1000 #define SYMBOL_ACCESSOR(name, description) inline Symbol* name(); 1001 PUBLIC_SYMBOL_LIST(SYMBOL_ACCESSOR) 1002 WELL_KNOWN_SYMBOL_LIST(SYMBOL_ACCESSOR) 1003 #undef SYMBOL_ACCESSOR 1004 1005 Object* root(RootListIndex index) { return roots_[index]; } 1006 Handle<Object> root_handle(RootListIndex index) { 1007 return Handle<Object>(&roots_[index]); 1008 } 1009 1010 // Generated code can embed this address to get access to the roots. 1011 Object** roots_array_start() { return roots_; } 1012 1013 // Sets the stub_cache_ (only used when expanding the dictionary). 1014 void SetRootCodeStubs(UnseededNumberDictionary* value) { 1015 roots_[kCodeStubsRootIndex] = value; 1016 } 1017 1018 void SetRootMaterializedObjects(FixedArray* objects) { 1019 roots_[kMaterializedObjectsRootIndex] = objects; 1020 } 1021 1022 void SetRootScriptList(Object* value) { 1023 roots_[kScriptListRootIndex] = value; 1024 } 1025 1026 void SetRootStringTable(StringTable* value) { 1027 roots_[kStringTableRootIndex] = value; 1028 } 1029 1030 void SetRootNoScriptSharedFunctionInfos(Object* value) { 1031 roots_[kNoScriptSharedFunctionInfosRootIndex] = value; 1032 } 1033 1034 // Set the stack limit in the roots_ array. Some architectures generate 1035 // code that looks here, because it is faster than loading from the static 1036 // jslimit_/real_jslimit_ variable in the StackGuard. 1037 void SetStackLimits(); 1038 1039 // The stack limit is thread-dependent. To be able to reproduce the same 1040 // snapshot blob, we need to reset it before serializing. 1041 void ClearStackLimits(); 1042 1043 // Generated code can treat direct references to this root as constant. 1044 bool RootCanBeTreatedAsConstant(RootListIndex root_index); 1045 1046 Map* MapForFixedTypedArray(ExternalArrayType array_type); 1047 RootListIndex RootIndexForFixedTypedArray(ExternalArrayType array_type); 1048 1049 RootListIndex RootIndexForEmptyFixedTypedArray(ElementsKind kind); 1050 FixedTypedArrayBase* EmptyFixedTypedArrayForMap(Map* map); 1051 1052 void RegisterStrongRoots(Object** start, Object** end); 1053 void UnregisterStrongRoots(Object** start); 1054 1055 // =========================================================================== 1056 // Inline allocation. ======================================================== 1057 // =========================================================================== 1058 1059 // Indicates whether inline bump-pointer allocation has been disabled. 1060 bool inline_allocation_disabled() { return inline_allocation_disabled_; } 1061 1062 // Switch whether inline bump-pointer allocation should be used. 1063 void EnableInlineAllocation(); 1064 void DisableInlineAllocation(); 1065 1066 // =========================================================================== 1067 // Methods triggering GCs. =================================================== 1068 // =========================================================================== 1069 1070 // Performs garbage collection operation. 1071 // Returns whether there is a chance that another major GC could 1072 // collect more garbage. 1073 inline bool CollectGarbage( 1074 AllocationSpace space, const char* gc_reason = NULL, 1075 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1076 1077 // Performs a full garbage collection. If (flags & kMakeHeapIterableMask) is 1078 // non-zero, then the slower precise sweeper is used, which leaves the heap 1079 // in a state where we can iterate over the heap visiting all objects. 1080 void CollectAllGarbage( 1081 int flags = kFinalizeIncrementalMarkingMask, const char* gc_reason = NULL, 1082 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1083 1084 // Last hope GC, should try to squeeze as much as possible. 1085 void CollectAllAvailableGarbage(const char* gc_reason = NULL); 1086 1087 // Reports and external memory pressure event, either performs a major GC or 1088 // completes incremental marking in order to free external resources. 1089 void ReportExternalMemoryPressure(const char* gc_reason = NULL); 1090 1091 // Invoked when GC was requested via the stack guard. 1092 void HandleGCRequest(); 1093 1094 // =========================================================================== 1095 // Iterators. ================================================================ 1096 // =========================================================================== 1097 1098 // Iterates over all roots in the heap. 1099 void IterateRoots(ObjectVisitor* v, VisitMode mode); 1100 // Iterates over all strong roots in the heap. 1101 void IterateStrongRoots(ObjectVisitor* v, VisitMode mode); 1102 // Iterates over entries in the smi roots list. Only interesting to the 1103 // serializer/deserializer, since GC does not care about smis. 1104 void IterateSmiRoots(ObjectVisitor* v); 1105 // Iterates over all the other roots in the heap. 1106 void IterateWeakRoots(ObjectVisitor* v, VisitMode mode); 1107 1108 // Iterate pointers of promoted objects. 1109 void IteratePromotedObject(HeapObject* target, int size, 1110 bool was_marked_black, 1111 ObjectSlotCallback callback); 1112 1113 void IteratePromotedObjectPointers(HeapObject* object, Address start, 1114 Address end, bool record_slots, 1115 ObjectSlotCallback callback); 1116 1117 // =========================================================================== 1118 // Store buffer API. ========================================================= 1119 // =========================================================================== 1120 1121 // Write barrier support for object[offset] = o; 1122 inline void RecordWrite(Object* object, int offset, Object* o); 1123 inline void RecordFixedArrayElements(FixedArray* array, int offset, 1124 int length); 1125 1126 Address* store_buffer_top_address() { return store_buffer()->top_address(); } 1127 1128 void ClearRecordedSlot(HeapObject* object, Object** slot); 1129 void ClearRecordedSlotRange(Address start, Address end); 1130 1131 // =========================================================================== 1132 // Incremental marking API. ================================================== 1133 // =========================================================================== 1134 1135 // Start incremental marking and ensure that idle time handler can perform 1136 // incremental steps. 1137 void StartIdleIncrementalMarking(); 1138 1139 // Starts incremental marking assuming incremental marking is currently 1140 // stopped. 1141 void StartIncrementalMarking(int gc_flags = kNoGCFlags, 1142 const GCCallbackFlags gc_callback_flags = 1143 GCCallbackFlags::kNoGCCallbackFlags, 1144 const char* reason = nullptr); 1145 1146 void FinalizeIncrementalMarkingIfComplete(const char* comment); 1147 1148 bool TryFinalizeIdleIncrementalMarking(double idle_time_in_ms); 1149 1150 void RegisterReservationsForBlackAllocation(Reservation* reservations); 1151 1152 IncrementalMarking* incremental_marking() { return incremental_marking_; } 1153 1154 // =========================================================================== 1155 // External string table API. ================================================ 1156 // =========================================================================== 1157 1158 // Registers an external string. 1159 inline void RegisterExternalString(String* string); 1160 1161 // Finalizes an external string by deleting the associated external 1162 // data and clearing the resource pointer. 1163 inline void FinalizeExternalString(String* string); 1164 1165 // =========================================================================== 1166 // Methods checking/returning the space of a given object/address. =========== 1167 // =========================================================================== 1168 1169 // Returns whether the object resides in new space. 1170 inline bool InNewSpace(Object* object); 1171 inline bool InFromSpace(Object* object); 1172 inline bool InToSpace(Object* object); 1173 1174 // Returns whether the object resides in old space. 1175 inline bool InOldSpace(Object* object); 1176 1177 // Checks whether an address/object in the heap (including auxiliary 1178 // area and unused area). 1179 bool Contains(HeapObject* value); 1180 1181 // Checks whether an address/object in a space. 1182 // Currently used by tests, serialization and heap verification only. 1183 bool InSpace(HeapObject* value, AllocationSpace space); 1184 1185 // Slow methods that can be used for verification as they can also be used 1186 // with off-heap Addresses. 1187 bool ContainsSlow(Address addr); 1188 bool InSpaceSlow(Address addr, AllocationSpace space); 1189 inline bool InNewSpaceSlow(Address address); 1190 inline bool InOldSpaceSlow(Address address); 1191 1192 // =========================================================================== 1193 // Object statistics tracking. =============================================== 1194 // =========================================================================== 1195 1196 // Returns the number of buckets used by object statistics tracking during a 1197 // major GC. Note that the following methods fail gracefully when the bounds 1198 // are exceeded though. 1199 size_t NumberOfTrackedHeapObjectTypes(); 1200 1201 // Returns object statistics about count and size at the last major GC. 1202 // Objects are being grouped into buckets that roughly resemble existing 1203 // instance types. 1204 size_t ObjectCountAtLastGC(size_t index); 1205 size_t ObjectSizeAtLastGC(size_t index); 1206 1207 // Retrieves names of buckets used by object statistics tracking. 1208 bool GetObjectTypeName(size_t index, const char** object_type, 1209 const char** object_sub_type); 1210 1211 // =========================================================================== 1212 // Code statistics. ========================================================== 1213 // =========================================================================== 1214 1215 // Collect code (Code and BytecodeArray objects) statistics. 1216 void CollectCodeStatistics(); 1217 1218 // =========================================================================== 1219 // GC statistics. ============================================================ 1220 // =========================================================================== 1221 1222 // Returns the maximum amount of memory reserved for the heap. 1223 intptr_t MaxReserved() { 1224 return 2 * max_semi_space_size_ + max_old_generation_size_; 1225 } 1226 int MaxSemiSpaceSize() { return max_semi_space_size_; } 1227 int InitialSemiSpaceSize() { return initial_semispace_size_; } 1228 intptr_t MaxOldGenerationSize() { return max_old_generation_size_; } 1229 intptr_t MaxExecutableSize() { return max_executable_size_; } 1230 1231 // Returns the capacity of the heap in bytes w/o growing. Heap grows when 1232 // more spaces are needed until it reaches the limit. 1233 intptr_t Capacity(); 1234 1235 // Returns the capacity of the old generation. 1236 intptr_t OldGenerationCapacity(); 1237 1238 // Returns the amount of memory currently committed for the heap. 1239 intptr_t CommittedMemory(); 1240 1241 // Returns the amount of memory currently committed for the old space. 1242 intptr_t CommittedOldGenerationMemory(); 1243 1244 // Returns the amount of executable memory currently committed for the heap. 1245 intptr_t CommittedMemoryExecutable(); 1246 1247 // Returns the amount of phyical memory currently committed for the heap. 1248 size_t CommittedPhysicalMemory(); 1249 1250 // Returns the maximum amount of memory ever committed for the heap. 1251 intptr_t MaximumCommittedMemory() { return maximum_committed_; } 1252 1253 // Updates the maximum committed memory for the heap. Should be called 1254 // whenever a space grows. 1255 void UpdateMaximumCommitted(); 1256 1257 // Returns the available bytes in space w/o growing. 1258 // Heap doesn't guarantee that it can allocate an object that requires 1259 // all available bytes. Check MaxHeapObjectSize() instead. 1260 intptr_t Available(); 1261 1262 // Returns of size of all objects residing in the heap. 1263 intptr_t SizeOfObjects(); 1264 1265 void UpdateSurvivalStatistics(int start_new_space_size); 1266 1267 inline void IncrementPromotedObjectsSize(intptr_t object_size) { 1268 DCHECK_GE(object_size, 0); 1269 promoted_objects_size_ += object_size; 1270 } 1271 inline intptr_t promoted_objects_size() { return promoted_objects_size_; } 1272 1273 inline void IncrementSemiSpaceCopiedObjectSize(intptr_t object_size) { 1274 DCHECK_GE(object_size, 0); 1275 semi_space_copied_object_size_ += object_size; 1276 } 1277 inline intptr_t semi_space_copied_object_size() { 1278 return semi_space_copied_object_size_; 1279 } 1280 1281 inline intptr_t SurvivedNewSpaceObjectSize() { 1282 return promoted_objects_size_ + semi_space_copied_object_size_; 1283 } 1284 1285 inline void IncrementNodesDiedInNewSpace() { nodes_died_in_new_space_++; } 1286 1287 inline void IncrementNodesCopiedInNewSpace() { nodes_copied_in_new_space_++; } 1288 1289 inline void IncrementNodesPromoted() { nodes_promoted_++; } 1290 1291 inline void IncrementYoungSurvivorsCounter(intptr_t survived) { 1292 DCHECK_GE(survived, 0); 1293 survived_last_scavenge_ = survived; 1294 survived_since_last_expansion_ += survived; 1295 } 1296 1297 inline intptr_t PromotedTotalSize() { 1298 int64_t total = PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize(); 1299 if (total > std::numeric_limits<intptr_t>::max()) { 1300 // TODO(erikcorry): Use uintptr_t everywhere we do heap size calculations. 1301 return std::numeric_limits<intptr_t>::max(); 1302 } 1303 if (total < 0) return 0; 1304 return static_cast<intptr_t>(total); 1305 } 1306 1307 void UpdateNewSpaceAllocationCounter() { 1308 new_space_allocation_counter_ = NewSpaceAllocationCounter(); 1309 } 1310 1311 size_t NewSpaceAllocationCounter() { 1312 return new_space_allocation_counter_ + new_space()->AllocatedSinceLastGC(); 1313 } 1314 1315 // This should be used only for testing. 1316 void set_new_space_allocation_counter(size_t new_value) { 1317 new_space_allocation_counter_ = new_value; 1318 } 1319 1320 void UpdateOldGenerationAllocationCounter() { 1321 old_generation_allocation_counter_ = OldGenerationAllocationCounter(); 1322 } 1323 1324 size_t OldGenerationAllocationCounter() { 1325 return old_generation_allocation_counter_ + PromotedSinceLastGC(); 1326 } 1327 1328 // This should be used only for testing. 1329 void set_old_generation_allocation_counter(size_t new_value) { 1330 old_generation_allocation_counter_ = new_value; 1331 } 1332 1333 size_t PromotedSinceLastGC() { 1334 return PromotedSpaceSizeOfObjects() - old_generation_size_at_last_gc_; 1335 } 1336 1337 int gc_count() const { return gc_count_; } 1338 1339 // Returns the size of objects residing in non new spaces. 1340 intptr_t PromotedSpaceSizeOfObjects(); 1341 1342 double total_regexp_code_generated() { return total_regexp_code_generated_; } 1343 void IncreaseTotalRegexpCodeGenerated(int size) { 1344 total_regexp_code_generated_ += size; 1345 } 1346 1347 void IncrementCodeGeneratedBytes(bool is_crankshafted, int size) { 1348 if (is_crankshafted) { 1349 crankshaft_codegen_bytes_generated_ += size; 1350 } else { 1351 full_codegen_bytes_generated_ += size; 1352 } 1353 } 1354 1355 // =========================================================================== 1356 // Prologue/epilogue callback methods.======================================== 1357 // =========================================================================== 1358 1359 void AddGCPrologueCallback(v8::Isolate::GCCallback callback, 1360 GCType gc_type_filter, bool pass_isolate = true); 1361 void RemoveGCPrologueCallback(v8::Isolate::GCCallback callback); 1362 1363 void AddGCEpilogueCallback(v8::Isolate::GCCallback callback, 1364 GCType gc_type_filter, bool pass_isolate = true); 1365 void RemoveGCEpilogueCallback(v8::Isolate::GCCallback callback); 1366 1367 void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags); 1368 void CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags); 1369 1370 // =========================================================================== 1371 // Allocation methods. ======================================================= 1372 // =========================================================================== 1373 1374 // Creates a filler object and returns a heap object immediately after it. 1375 MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object, 1376 int filler_size); 1377 1378 // Creates a filler object if needed for alignment and returns a heap object 1379 // immediately after it. If any space is left after the returned object, 1380 // another filler object is created so the over allocated memory is iterable. 1381 MUST_USE_RESULT HeapObject* AlignWithFiller(HeapObject* object, 1382 int object_size, 1383 int allocation_size, 1384 AllocationAlignment alignment); 1385 1386 // =========================================================================== 1387 // ArrayBuffer tracking. ===================================================== 1388 // =========================================================================== 1389 1390 void RegisterNewArrayBuffer(JSArrayBuffer* buffer); 1391 void UnregisterArrayBuffer(JSArrayBuffer* buffer); 1392 1393 // =========================================================================== 1394 // Allocation site tracking. ================================================= 1395 // =========================================================================== 1396 1397 // Updates the AllocationSite of a given {object}. If the global prenuring 1398 // storage is passed as {pretenuring_feedback} the memento found count on 1399 // the corresponding allocation site is immediately updated and an entry 1400 // in the hash map is created. Otherwise the entry (including a the count 1401 // value) is cached on the local pretenuring feedback. 1402 template <UpdateAllocationSiteMode mode> 1403 inline void UpdateAllocationSite(HeapObject* object, 1404 base::HashMap* pretenuring_feedback); 1405 1406 // Removes an entry from the global pretenuring storage. 1407 inline void RemoveAllocationSitePretenuringFeedback(AllocationSite* site); 1408 1409 // Merges local pretenuring feedback into the global one. Note that this 1410 // method needs to be called after evacuation, as allocation sites may be 1411 // evacuated and this method resolves forward pointers accordingly. 1412 void MergeAllocationSitePretenuringFeedback( 1413 const base::HashMap& local_pretenuring_feedback); 1414 1415 // ============================================================================= 1416 1417 #ifdef VERIFY_HEAP 1418 // Verify the heap is in its normal state before or after a GC. 1419 void Verify(); 1420 #endif 1421 1422 #ifdef DEBUG 1423 void set_allocation_timeout(int timeout) { allocation_timeout_ = timeout; } 1424 1425 void TracePathToObjectFrom(Object* target, Object* root); 1426 void TracePathToObject(Object* target); 1427 void TracePathToGlobal(); 1428 1429 void Print(); 1430 void PrintHandles(); 1431 1432 // Report heap statistics. 1433 void ReportHeapStatistics(const char* title); 1434 void ReportCodeStatistics(const char* title); 1435 #endif 1436 1437 private: 1438 class PretenuringScope; 1439 1440 // External strings table is a place where all external strings are 1441 // registered. We need to keep track of such strings to properly 1442 // finalize them. 1443 class ExternalStringTable { 1444 public: 1445 // Registers an external string. 1446 inline void AddString(String* string); 1447 1448 inline void Iterate(ObjectVisitor* v); 1449 1450 // Restores internal invariant and gets rid of collected strings. 1451 // Must be called after each Iterate() that modified the strings. 1452 void CleanUp(); 1453 1454 // Destroys all allocated memory. 1455 void TearDown(); 1456 1457 private: 1458 explicit ExternalStringTable(Heap* heap) : heap_(heap) {} 1459 1460 inline void Verify(); 1461 1462 inline void AddOldString(String* string); 1463 1464 // Notifies the table that only a prefix of the new list is valid. 1465 inline void ShrinkNewStrings(int position); 1466 1467 // To speed up scavenge collections new space string are kept 1468 // separate from old space strings. 1469 List<Object*> new_space_strings_; 1470 List<Object*> old_space_strings_; 1471 1472 Heap* heap_; 1473 1474 friend class Heap; 1475 1476 DISALLOW_COPY_AND_ASSIGN(ExternalStringTable); 1477 }; 1478 1479 struct StrongRootsList; 1480 1481 struct StringTypeTable { 1482 InstanceType type; 1483 int size; 1484 RootListIndex index; 1485 }; 1486 1487 struct ConstantStringTable { 1488 const char* contents; 1489 RootListIndex index; 1490 }; 1491 1492 struct StructTable { 1493 InstanceType type; 1494 int size; 1495 RootListIndex index; 1496 }; 1497 1498 struct GCCallbackPair { 1499 GCCallbackPair(v8::Isolate::GCCallback callback, GCType gc_type, 1500 bool pass_isolate) 1501 : callback(callback), gc_type(gc_type), pass_isolate(pass_isolate) {} 1502 1503 bool operator==(const GCCallbackPair& other) const { 1504 return other.callback == callback; 1505 } 1506 1507 v8::Isolate::GCCallback callback; 1508 GCType gc_type; 1509 bool pass_isolate; 1510 }; 1511 1512 typedef String* (*ExternalStringTableUpdaterCallback)(Heap* heap, 1513 Object** pointer); 1514 1515 static const int kInitialStringTableSize = 2048; 1516 static const int kInitialEvalCacheSize = 64; 1517 static const int kInitialNumberStringCacheSize = 256; 1518 1519 static const int kRememberedUnmappedPages = 128; 1520 1521 static const StringTypeTable string_type_table[]; 1522 static const ConstantStringTable constant_string_table[]; 1523 static const StructTable struct_table[]; 1524 1525 static const int kYoungSurvivalRateHighThreshold = 90; 1526 static const int kYoungSurvivalRateAllowedDeviation = 15; 1527 static const int kOldSurvivalRateLowThreshold = 10; 1528 1529 static const int kMaxMarkCompactsInIdleRound = 7; 1530 static const int kIdleScavengeThreshold = 5; 1531 1532 static const int kInitialFeedbackCapacity = 256; 1533 1534 Heap(); 1535 1536 static String* UpdateNewSpaceReferenceInExternalStringTableEntry( 1537 Heap* heap, Object** pointer); 1538 1539 // Selects the proper allocation space based on the pretenuring decision. 1540 static AllocationSpace SelectSpace(PretenureFlag pretenure) { 1541 return (pretenure == TENURED) ? OLD_SPACE : NEW_SPACE; 1542 } 1543 1544 #define ROOT_ACCESSOR(type, name, camel_name) \ 1545 inline void set_##name(type* value); 1546 ROOT_LIST(ROOT_ACCESSOR) 1547 #undef ROOT_ACCESSOR 1548 1549 StoreBuffer* store_buffer() { return &store_buffer_; } 1550 1551 void set_current_gc_flags(int flags) { 1552 current_gc_flags_ = flags; 1553 DCHECK(!ShouldFinalizeIncrementalMarking() || 1554 !ShouldAbortIncrementalMarking()); 1555 } 1556 1557 inline bool ShouldReduceMemory() const { 1558 return current_gc_flags_ & kReduceMemoryFootprintMask; 1559 } 1560 1561 inline bool ShouldAbortIncrementalMarking() const { 1562 return current_gc_flags_ & kAbortIncrementalMarkingMask; 1563 } 1564 1565 inline bool ShouldFinalizeIncrementalMarking() const { 1566 return current_gc_flags_ & kFinalizeIncrementalMarkingMask; 1567 } 1568 1569 void PreprocessStackTraces(); 1570 1571 // Checks whether a global GC is necessary 1572 GarbageCollector SelectGarbageCollector(AllocationSpace space, 1573 const char** reason); 1574 1575 // Make sure there is a filler value behind the top of the new space 1576 // so that the GC does not confuse some unintialized/stale memory 1577 // with the allocation memento of the object at the top 1578 void EnsureFillerObjectAtTop(); 1579 1580 // Ensure that we have swept all spaces in such a way that we can iterate 1581 // over all objects. May cause a GC. 1582 void MakeHeapIterable(); 1583 1584 // Performs garbage collection operation. 1585 // Returns whether there is a chance that another major GC could 1586 // collect more garbage. 1587 bool CollectGarbage( 1588 GarbageCollector collector, const char* gc_reason, 1589 const char* collector_reason, 1590 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1591 1592 // Performs garbage collection 1593 // Returns whether there is a chance another major GC could 1594 // collect more garbage. 1595 bool PerformGarbageCollection( 1596 GarbageCollector collector, 1597 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1598 1599 inline void UpdateOldSpaceLimits(); 1600 1601 // Initializes a JSObject based on its map. 1602 void InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties, 1603 Map* map); 1604 1605 // Initializes JSObject body starting at given offset. 1606 void InitializeJSObjectBody(JSObject* obj, Map* map, int start_offset); 1607 1608 void InitializeAllocationMemento(AllocationMemento* memento, 1609 AllocationSite* allocation_site); 1610 1611 bool CreateInitialMaps(); 1612 void CreateInitialObjects(); 1613 1614 // These five Create*EntryStub functions are here and forced to not be inlined 1615 // because of a gcc-4.4 bug that assigns wrong vtable entries. 1616 NO_INLINE(void CreateJSEntryStub()); 1617 NO_INLINE(void CreateJSConstructEntryStub()); 1618 1619 void CreateFixedStubs(); 1620 1621 HeapObject* DoubleAlignForDeserialization(HeapObject* object, int size); 1622 1623 // Commits from space if it is uncommitted. 1624 void EnsureFromSpaceIsCommitted(); 1625 1626 // Uncommit unused semi space. 1627 bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); } 1628 1629 // Fill in bogus values in from space 1630 void ZapFromSpace(); 1631 1632 // Deopts all code that contains allocation instruction which are tenured or 1633 // not tenured. Moreover it clears the pretenuring allocation site statistics. 1634 void ResetAllAllocationSitesDependentCode(PretenureFlag flag); 1635 1636 // Evaluates local pretenuring for the old space and calls 1637 // ResetAllTenuredAllocationSitesDependentCode if too many objects died in 1638 // the old space. 1639 void EvaluateOldSpaceLocalPretenuring(uint64_t size_of_objects_before_gc); 1640 1641 // Record statistics before and after garbage collection. 1642 void ReportStatisticsBeforeGC(); 1643 void ReportStatisticsAfterGC(); 1644 1645 // Creates and installs the full-sized number string cache. 1646 int FullSizeNumberStringCacheLength(); 1647 // Flush the number to string cache. 1648 void FlushNumberStringCache(); 1649 1650 // TODO(hpayer): Allocation site pretenuring may make this method obsolete. 1651 // Re-visit incremental marking heuristics. 1652 bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; } 1653 1654 void ConfigureInitialOldGenerationSize(); 1655 1656 bool HasLowYoungGenerationAllocationRate(); 1657 bool HasLowOldGenerationAllocationRate(); 1658 double YoungGenerationMutatorUtilization(); 1659 double OldGenerationMutatorUtilization(); 1660 1661 void ReduceNewSpaceSize(); 1662 1663 bool TryFinalizeIdleIncrementalMarking( 1664 double idle_time_in_ms, size_t size_of_objects, 1665 size_t mark_compact_speed_in_bytes_per_ms); 1666 1667 GCIdleTimeHeapState ComputeHeapState(); 1668 1669 bool PerformIdleTimeAction(GCIdleTimeAction action, 1670 GCIdleTimeHeapState heap_state, 1671 double deadline_in_ms); 1672 1673 void IdleNotificationEpilogue(GCIdleTimeAction action, 1674 GCIdleTimeHeapState heap_state, double start_ms, 1675 double deadline_in_ms); 1676 1677 inline void UpdateAllocationsHash(HeapObject* object); 1678 inline void UpdateAllocationsHash(uint32_t value); 1679 void PrintAlloctionsHash(); 1680 1681 void AddToRingBuffer(const char* string); 1682 void GetFromRingBuffer(char* buffer); 1683 1684 void CompactRetainedMaps(ArrayList* retained_maps); 1685 1686 void CollectGarbageOnMemoryPressure(const char* source); 1687 1688 // Attempt to over-approximate the weak closure by marking object groups and 1689 // implicit references from global handles, but don't atomically complete 1690 // marking. If we continue to mark incrementally, we might have marked 1691 // objects that die later. 1692 void FinalizeIncrementalMarking(const char* gc_reason); 1693 1694 // Returns the timer used for a given GC type. 1695 // - GCScavenger: young generation GC 1696 // - GCCompactor: full GC 1697 // - GCFinalzeMC: finalization of incremental full GC 1698 // - GCFinalizeMCReduceMemory: finalization of incremental full GC with 1699 // memory reduction 1700 HistogramTimer* GCTypeTimer(GarbageCollector collector); 1701 1702 // =========================================================================== 1703 // Pretenuring. ============================================================== 1704 // =========================================================================== 1705 1706 // Pretenuring decisions are made based on feedback collected during new space 1707 // evacuation. Note that between feedback collection and calling this method 1708 // object in old space must not move. 1709 void ProcessPretenuringFeedback(); 1710 1711 // =========================================================================== 1712 // Actual GC. ================================================================ 1713 // =========================================================================== 1714 1715 // Code that should be run before and after each GC. Includes some 1716 // reporting/verification activities when compiled with DEBUG set. 1717 void GarbageCollectionPrologue(); 1718 void GarbageCollectionEpilogue(); 1719 1720 // Performs a major collection in the whole heap. 1721 void MarkCompact(); 1722 1723 // Code to be run before and after mark-compact. 1724 void MarkCompactPrologue(); 1725 void MarkCompactEpilogue(); 1726 1727 // Performs a minor collection in new generation. 1728 void Scavenge(); 1729 1730 Address DoScavenge(ObjectVisitor* scavenge_visitor, Address new_space_front, 1731 PromotionMode promotion_mode); 1732 1733 void UpdateNewSpaceReferencesInExternalStringTable( 1734 ExternalStringTableUpdaterCallback updater_func); 1735 1736 void UpdateReferencesInExternalStringTable( 1737 ExternalStringTableUpdaterCallback updater_func); 1738 1739 void ProcessAllWeakReferences(WeakObjectRetainer* retainer); 1740 void ProcessYoungWeakReferences(WeakObjectRetainer* retainer); 1741 void ProcessNativeContexts(WeakObjectRetainer* retainer); 1742 void ProcessAllocationSites(WeakObjectRetainer* retainer); 1743 void ProcessWeakListRoots(WeakObjectRetainer* retainer); 1744 1745 // =========================================================================== 1746 // GC statistics. ============================================================ 1747 // =========================================================================== 1748 1749 inline intptr_t OldGenerationSpaceAvailable() { 1750 return old_generation_allocation_limit_ - PromotedTotalSize(); 1751 } 1752 1753 // Returns maximum GC pause. 1754 double get_max_gc_pause() { return max_gc_pause_; } 1755 1756 // Returns maximum size of objects alive after GC. 1757 intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; } 1758 1759 // Returns minimal interval between two subsequent collections. 1760 double get_min_in_mutator() { return min_in_mutator_; } 1761 1762 // Update GC statistics that are tracked on the Heap. 1763 void UpdateCumulativeGCStatistics(double duration, double spent_in_mutator, 1764 double marking_time); 1765 1766 bool MaximumSizeScavenge() { return maximum_size_scavenges_ > 0; } 1767 1768 // =========================================================================== 1769 // Growing strategy. ========================================================= 1770 // =========================================================================== 1771 1772 // Decrease the allocation limit if the new limit based on the given 1773 // parameters is lower than the current limit. 1774 void DampenOldGenerationAllocationLimit(intptr_t old_gen_size, 1775 double gc_speed, 1776 double mutator_speed); 1777 1778 1779 // Calculates the allocation limit based on a given growing factor and a 1780 // given old generation size. 1781 intptr_t CalculateOldGenerationAllocationLimit(double factor, 1782 intptr_t old_gen_size); 1783 1784 // Sets the allocation limit to trigger the next full garbage collection. 1785 void SetOldGenerationAllocationLimit(intptr_t old_gen_size, double gc_speed, 1786 double mutator_speed); 1787 1788 // =========================================================================== 1789 // Idle notification. ======================================================== 1790 // =========================================================================== 1791 1792 bool RecentIdleNotificationHappened(); 1793 void ScheduleIdleScavengeIfNeeded(int bytes_allocated); 1794 1795 // =========================================================================== 1796 // HeapIterator helpers. ===================================================== 1797 // =========================================================================== 1798 1799 void heap_iterator_start() { heap_iterator_depth_++; } 1800 1801 void heap_iterator_end() { heap_iterator_depth_--; } 1802 1803 bool in_heap_iterator() { return heap_iterator_depth_ > 0; } 1804 1805 // =========================================================================== 1806 // Allocation methods. ======================================================= 1807 // =========================================================================== 1808 1809 // Returns a deep copy of the JavaScript object. 1810 // Properties and elements are copied too. 1811 // Optionally takes an AllocationSite to be appended in an AllocationMemento. 1812 MUST_USE_RESULT AllocationResult CopyJSObject(JSObject* source, 1813 AllocationSite* site = NULL); 1814 1815 // Allocates a JS Map in the heap. 1816 MUST_USE_RESULT AllocationResult 1817 AllocateMap(InstanceType instance_type, int instance_size, 1818 ElementsKind elements_kind = TERMINAL_FAST_ELEMENTS_KIND); 1819 1820 // Allocates and initializes a new JavaScript object based on a 1821 // constructor. 1822 // If allocation_site is non-null, then a memento is emitted after the object 1823 // that points to the site. 1824 MUST_USE_RESULT AllocationResult AllocateJSObject( 1825 JSFunction* constructor, PretenureFlag pretenure = NOT_TENURED, 1826 AllocationSite* allocation_site = NULL); 1827 1828 // Allocates and initializes a new JavaScript object based on a map. 1829 // Passing an allocation site means that a memento will be created that 1830 // points to the site. 1831 MUST_USE_RESULT AllocationResult 1832 AllocateJSObjectFromMap(Map* map, PretenureFlag pretenure = NOT_TENURED, 1833 AllocationSite* allocation_site = NULL); 1834 1835 // Allocates a HeapNumber from value. 1836 MUST_USE_RESULT AllocationResult 1837 AllocateHeapNumber(double value, MutableMode mode = IMMUTABLE, 1838 PretenureFlag pretenure = NOT_TENURED); 1839 1840 // Allocates SIMD values from the given lane values. 1841 #define SIMD_ALLOCATE_DECLARATION(TYPE, Type, type, lane_count, lane_type) \ 1842 AllocationResult Allocate##Type(lane_type lanes[lane_count], \ 1843 PretenureFlag pretenure = NOT_TENURED); 1844 SIMD128_TYPES(SIMD_ALLOCATE_DECLARATION) 1845 #undef SIMD_ALLOCATE_DECLARATION 1846 1847 // Allocates a byte array of the specified length 1848 MUST_USE_RESULT AllocationResult 1849 AllocateByteArray(int length, PretenureFlag pretenure = NOT_TENURED); 1850 1851 // Allocates a bytecode array with given contents. 1852 MUST_USE_RESULT AllocationResult 1853 AllocateBytecodeArray(int length, const byte* raw_bytecodes, int frame_size, 1854 int parameter_count, FixedArray* constant_pool); 1855 1856 MUST_USE_RESULT AllocationResult CopyCode(Code* code); 1857 1858 MUST_USE_RESULT AllocationResult 1859 CopyBytecodeArray(BytecodeArray* bytecode_array); 1860 1861 // Allocates a fixed array initialized with undefined values 1862 MUST_USE_RESULT AllocationResult 1863 AllocateFixedArray(int length, PretenureFlag pretenure = NOT_TENURED); 1864 1865 // Allocate an uninitialized object. The memory is non-executable if the 1866 // hardware and OS allow. This is the single choke-point for allocations 1867 // performed by the runtime and should not be bypassed (to extend this to 1868 // inlined allocations, use the Heap::DisableInlineAllocation() support). 1869 MUST_USE_RESULT inline AllocationResult AllocateRaw( 1870 int size_in_bytes, AllocationSpace space, 1871 AllocationAlignment aligment = kWordAligned); 1872 1873 // Allocates a heap object based on the map. 1874 MUST_USE_RESULT AllocationResult 1875 Allocate(Map* map, AllocationSpace space, 1876 AllocationSite* allocation_site = NULL); 1877 1878 // Allocates a partial map for bootstrapping. 1879 MUST_USE_RESULT AllocationResult 1880 AllocatePartialMap(InstanceType instance_type, int instance_size); 1881 1882 // Allocate a block of memory in the given space (filled with a filler). 1883 // Used as a fall-back for generated code when the space is full. 1884 MUST_USE_RESULT AllocationResult 1885 AllocateFillerObject(int size, bool double_align, AllocationSpace space); 1886 1887 // Allocate an uninitialized fixed array. 1888 MUST_USE_RESULT AllocationResult 1889 AllocateRawFixedArray(int length, PretenureFlag pretenure); 1890 1891 // Allocate an uninitialized fixed double array. 1892 MUST_USE_RESULT AllocationResult 1893 AllocateRawFixedDoubleArray(int length, PretenureFlag pretenure); 1894 1895 // Allocate an initialized fixed array with the given filler value. 1896 MUST_USE_RESULT AllocationResult 1897 AllocateFixedArrayWithFiller(int length, PretenureFlag pretenure, 1898 Object* filler); 1899 1900 // Allocate and partially initializes a String. There are two String 1901 // encodings: one-byte and two-byte. These functions allocate a string of 1902 // the given length and set its map and length fields. The characters of 1903 // the string are uninitialized. 1904 MUST_USE_RESULT AllocationResult 1905 AllocateRawOneByteString(int length, PretenureFlag pretenure); 1906 MUST_USE_RESULT AllocationResult 1907 AllocateRawTwoByteString(int length, PretenureFlag pretenure); 1908 1909 // Allocates an internalized string in old space based on the character 1910 // stream. 1911 MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringFromUtf8( 1912 Vector<const char> str, int chars, uint32_t hash_field); 1913 1914 MUST_USE_RESULT inline AllocationResult AllocateOneByteInternalizedString( 1915 Vector<const uint8_t> str, uint32_t hash_field); 1916 1917 MUST_USE_RESULT inline AllocationResult AllocateTwoByteInternalizedString( 1918 Vector<const uc16> str, uint32_t hash_field); 1919 1920 template <bool is_one_byte, typename T> 1921 MUST_USE_RESULT AllocationResult 1922 AllocateInternalizedStringImpl(T t, int chars, uint32_t hash_field); 1923 1924 template <typename T> 1925 MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringImpl( 1926 T t, int chars, uint32_t hash_field); 1927 1928 // Allocates an uninitialized fixed array. It must be filled by the caller. 1929 MUST_USE_RESULT AllocationResult AllocateUninitializedFixedArray(int length); 1930 1931 // Make a copy of src and return it. 1932 MUST_USE_RESULT inline AllocationResult CopyFixedArray(FixedArray* src); 1933 1934 // Make a copy of src, also grow the copy, and return the copy. 1935 MUST_USE_RESULT AllocationResult 1936 CopyFixedArrayAndGrow(FixedArray* src, int grow_by, PretenureFlag pretenure); 1937 1938 // Make a copy of src, also grow the copy, and return the copy. 1939 MUST_USE_RESULT AllocationResult CopyFixedArrayUpTo(FixedArray* src, 1940 int new_len, 1941 PretenureFlag pretenure); 1942 1943 // Make a copy of src, set the map, and return the copy. 1944 MUST_USE_RESULT AllocationResult 1945 CopyFixedArrayWithMap(FixedArray* src, Map* map); 1946 1947 // Make a copy of src and return it. 1948 MUST_USE_RESULT inline AllocationResult CopyFixedDoubleArray( 1949 FixedDoubleArray* src); 1950 1951 // Computes a single character string where the character has code. 1952 // A cache is used for one-byte (Latin1) codes. 1953 MUST_USE_RESULT AllocationResult 1954 LookupSingleCharacterStringFromCode(uint16_t code); 1955 1956 // Allocate a symbol in old space. 1957 MUST_USE_RESULT AllocationResult AllocateSymbol(); 1958 1959 // Allocates an external array of the specified length and type. 1960 MUST_USE_RESULT AllocationResult AllocateFixedTypedArrayWithExternalPointer( 1961 int length, ExternalArrayType array_type, void* external_pointer, 1962 PretenureFlag pretenure); 1963 1964 // Allocates a fixed typed array of the specified length and type. 1965 MUST_USE_RESULT AllocationResult 1966 AllocateFixedTypedArray(int length, ExternalArrayType array_type, 1967 bool initialize, PretenureFlag pretenure); 1968 1969 // Make a copy of src and return it. 1970 MUST_USE_RESULT AllocationResult CopyAndTenureFixedCOWArray(FixedArray* src); 1971 1972 // Make a copy of src, set the map, and return the copy. 1973 MUST_USE_RESULT AllocationResult 1974 CopyFixedDoubleArrayWithMap(FixedDoubleArray* src, Map* map); 1975 1976 // Allocates a fixed double array with uninitialized values. Returns 1977 MUST_USE_RESULT AllocationResult AllocateUninitializedFixedDoubleArray( 1978 int length, PretenureFlag pretenure = NOT_TENURED); 1979 1980 // Allocate empty fixed array. 1981 MUST_USE_RESULT AllocationResult AllocateEmptyFixedArray(); 1982 1983 // Allocate empty fixed typed array of given type. 1984 MUST_USE_RESULT AllocationResult 1985 AllocateEmptyFixedTypedArray(ExternalArrayType array_type); 1986 1987 // Allocate a tenured simple cell. 1988 MUST_USE_RESULT AllocationResult AllocateCell(Object* value); 1989 1990 // Allocate a tenured JS global property cell initialized with the hole. 1991 MUST_USE_RESULT AllocationResult AllocatePropertyCell(); 1992 1993 MUST_USE_RESULT AllocationResult AllocateWeakCell(HeapObject* value); 1994 1995 MUST_USE_RESULT AllocationResult AllocateTransitionArray(int capacity); 1996 1997 // Allocates a new utility object in the old generation. 1998 MUST_USE_RESULT AllocationResult AllocateStruct(InstanceType type); 1999 2000 // Allocates a new foreign object. 2001 MUST_USE_RESULT AllocationResult 2002 AllocateForeign(Address address, PretenureFlag pretenure = NOT_TENURED); 2003 2004 MUST_USE_RESULT AllocationResult 2005 AllocateCode(int object_size, bool immovable); 2006 2007 MUST_USE_RESULT AllocationResult InternalizeStringWithKey(HashTableKey* key); 2008 2009 MUST_USE_RESULT AllocationResult InternalizeString(String* str); 2010 2011 // =========================================================================== 2012 2013 void set_force_oom(bool value) { force_oom_ = value; } 2014 2015 // The amount of external memory registered through the API. 2016 int64_t external_memory_; 2017 2018 // The limit when to trigger memory pressure from the API. 2019 int64_t external_memory_limit_; 2020 2021 // Caches the amount of external memory registered at the last MC. 2022 int64_t external_memory_at_last_mark_compact_; 2023 2024 // The amount of memory that has been freed concurrently. 2025 base::AtomicNumber<intptr_t> external_memory_concurrently_freed_; 2026 2027 // This can be calculated directly from a pointer to the heap; however, it is 2028 // more expedient to get at the isolate directly from within Heap methods. 2029 Isolate* isolate_; 2030 2031 Object* roots_[kRootListLength]; 2032 2033 size_t code_range_size_; 2034 int max_semi_space_size_; 2035 int initial_semispace_size_; 2036 intptr_t max_old_generation_size_; 2037 intptr_t initial_old_generation_size_; 2038 bool old_generation_size_configured_; 2039 intptr_t max_executable_size_; 2040 intptr_t maximum_committed_; 2041 2042 // For keeping track of how much data has survived 2043 // scavenge since last new space expansion. 2044 intptr_t survived_since_last_expansion_; 2045 2046 // ... and since the last scavenge. 2047 intptr_t survived_last_scavenge_; 2048 2049 // This is not the depth of nested AlwaysAllocateScope's but rather a single 2050 // count, as scopes can be acquired from multiple tasks (read: threads). 2051 base::AtomicNumber<size_t> always_allocate_scope_count_; 2052 2053 // Stores the memory pressure level that set by MemoryPressureNotification 2054 // and reset by a mark-compact garbage collection. 2055 base::AtomicValue<MemoryPressureLevel> memory_pressure_level_; 2056 2057 // For keeping track of context disposals. 2058 int contexts_disposed_; 2059 2060 // The length of the retained_maps array at the time of context disposal. 2061 // This separates maps in the retained_maps array that were created before 2062 // and after context disposal. 2063 int number_of_disposed_maps_; 2064 2065 int global_ic_age_; 2066 2067 NewSpace new_space_; 2068 OldSpace* old_space_; 2069 OldSpace* code_space_; 2070 MapSpace* map_space_; 2071 LargeObjectSpace* lo_space_; 2072 HeapState gc_state_; 2073 int gc_post_processing_depth_; 2074 Address new_space_top_after_last_gc_; 2075 2076 // Returns the amount of external memory registered since last global gc. 2077 int64_t PromotedExternalMemorySize(); 2078 2079 // How many "runtime allocations" happened. 2080 uint32_t allocations_count_; 2081 2082 // Running hash over allocations performed. 2083 uint32_t raw_allocations_hash_; 2084 2085 // How many mark-sweep collections happened. 2086 unsigned int ms_count_; 2087 2088 // How many gc happened. 2089 unsigned int gc_count_; 2090 2091 // For post mortem debugging. 2092 int remembered_unmapped_pages_index_; 2093 Address remembered_unmapped_pages_[kRememberedUnmappedPages]; 2094 2095 #ifdef DEBUG 2096 // If the --gc-interval flag is set to a positive value, this 2097 // variable holds the value indicating the number of allocations 2098 // remain until the next failure and garbage collection. 2099 int allocation_timeout_; 2100 #endif // DEBUG 2101 2102 // Limit that triggers a global GC on the next (normally caused) GC. This 2103 // is checked when we have already decided to do a GC to help determine 2104 // which collector to invoke, before expanding a paged space in the old 2105 // generation and on every allocation in large object space. 2106 intptr_t old_generation_allocation_limit_; 2107 2108 // Indicates that an allocation has failed in the old generation since the 2109 // last GC. 2110 bool old_gen_exhausted_; 2111 2112 // Indicates that memory usage is more important than latency. 2113 // TODO(ulan): Merge it with memory reducer once chromium:490559 is fixed. 2114 bool optimize_for_memory_usage_; 2115 2116 // Indicates that inline bump-pointer allocation has been globally disabled 2117 // for all spaces. This is used to disable allocations in generated code. 2118 bool inline_allocation_disabled_; 2119 2120 // Weak list heads, threaded through the objects. 2121 // List heads are initialized lazily and contain the undefined_value at start. 2122 Object* native_contexts_list_; 2123 Object* allocation_sites_list_; 2124 2125 // List of encountered weak collections (JSWeakMap and JSWeakSet) during 2126 // marking. It is initialized during marking, destroyed after marking and 2127 // contains Smi(0) while marking is not active. 2128 Object* encountered_weak_collections_; 2129 2130 Object* encountered_weak_cells_; 2131 2132 Object* encountered_transition_arrays_; 2133 2134 List<GCCallbackPair> gc_epilogue_callbacks_; 2135 List<GCCallbackPair> gc_prologue_callbacks_; 2136 2137 // Total RegExp code ever generated 2138 double total_regexp_code_generated_; 2139 2140 int deferred_counters_[v8::Isolate::kUseCounterFeatureCount]; 2141 2142 GCTracer* tracer_; 2143 2144 int high_survival_rate_period_length_; 2145 intptr_t promoted_objects_size_; 2146 double promotion_ratio_; 2147 double promotion_rate_; 2148 intptr_t semi_space_copied_object_size_; 2149 intptr_t previous_semi_space_copied_object_size_; 2150 double semi_space_copied_rate_; 2151 int nodes_died_in_new_space_; 2152 int nodes_copied_in_new_space_; 2153 int nodes_promoted_; 2154 2155 // This is the pretenuring trigger for allocation sites that are in maybe 2156 // tenure state. When we switched to the maximum new space size we deoptimize 2157 // the code that belongs to the allocation site and derive the lifetime 2158 // of the allocation site. 2159 unsigned int maximum_size_scavenges_; 2160 2161 // Maximum GC pause. 2162 double max_gc_pause_; 2163 2164 // Total time spent in GC. 2165 double total_gc_time_ms_; 2166 2167 // Maximum size of objects alive after GC. 2168 intptr_t max_alive_after_gc_; 2169 2170 // Minimal interval between two subsequent collections. 2171 double min_in_mutator_; 2172 2173 // Cumulative GC time spent in marking. 2174 double marking_time_; 2175 2176 // Cumulative GC time spent in sweeping. 2177 double sweeping_time_; 2178 2179 // Last time an idle notification happened. 2180 double last_idle_notification_time_; 2181 2182 // Last time a garbage collection happened. 2183 double last_gc_time_; 2184 2185 Scavenger* scavenge_collector_; 2186 2187 MarkCompactCollector* mark_compact_collector_; 2188 2189 MemoryAllocator* memory_allocator_; 2190 2191 StoreBuffer store_buffer_; 2192 2193 IncrementalMarking* incremental_marking_; 2194 2195 GCIdleTimeHandler* gc_idle_time_handler_; 2196 2197 MemoryReducer* memory_reducer_; 2198 2199 ObjectStats* object_stats_; 2200 2201 ScavengeJob* scavenge_job_; 2202 2203 AllocationObserver* idle_scavenge_observer_; 2204 2205 // These two counters are monotomically increasing and never reset. 2206 size_t full_codegen_bytes_generated_; 2207 size_t crankshaft_codegen_bytes_generated_; 2208 2209 // This counter is increased before each GC and never reset. 2210 // To account for the bytes allocated since the last GC, use the 2211 // NewSpaceAllocationCounter() function. 2212 size_t new_space_allocation_counter_; 2213 2214 // This counter is increased before each GC and never reset. To 2215 // account for the bytes allocated since the last GC, use the 2216 // OldGenerationAllocationCounter() function. 2217 size_t old_generation_allocation_counter_; 2218 2219 // The size of objects in old generation after the last MarkCompact GC. 2220 size_t old_generation_size_at_last_gc_; 2221 2222 // If the --deopt_every_n_garbage_collections flag is set to a positive value, 2223 // this variable holds the number of garbage collections since the last 2224 // deoptimization triggered by garbage collection. 2225 int gcs_since_last_deopt_; 2226 2227 // The feedback storage is used to store allocation sites (keys) and how often 2228 // they have been visited (values) by finding a memento behind an object. The 2229 // storage is only alive temporary during a GC. The invariant is that all 2230 // pointers in this map are already fixed, i.e., they do not point to 2231 // forwarding pointers. 2232 base::HashMap* global_pretenuring_feedback_; 2233 2234 char trace_ring_buffer_[kTraceRingBufferSize]; 2235 // If it's not full then the data is from 0 to ring_buffer_end_. If it's 2236 // full then the data is from ring_buffer_end_ to the end of the buffer and 2237 // from 0 to ring_buffer_end_. 2238 bool ring_buffer_full_; 2239 size_t ring_buffer_end_; 2240 2241 // Shared state read by the scavenge collector and set by ScavengeObject. 2242 PromotionQueue promotion_queue_; 2243 2244 // Flag is set when the heap has been configured. The heap can be repeatedly 2245 // configured through the API until it is set up. 2246 bool configured_; 2247 2248 // Currently set GC flags that are respected by all GC components. 2249 int current_gc_flags_; 2250 2251 // Currently set GC callback flags that are used to pass information between 2252 // the embedder and V8's GC. 2253 GCCallbackFlags current_gc_callback_flags_; 2254 2255 ExternalStringTable external_string_table_; 2256 2257 base::Mutex relocation_mutex_; 2258 2259 int gc_callbacks_depth_; 2260 2261 bool deserialization_complete_; 2262 2263 StrongRootsList* strong_roots_list_; 2264 2265 // The depth of HeapIterator nestings. 2266 int heap_iterator_depth_; 2267 2268 // Used for testing purposes. 2269 bool force_oom_; 2270 2271 // Classes in "heap" can be friends. 2272 friend class AlwaysAllocateScope; 2273 friend class GCCallbacksScope; 2274 friend class GCTracer; 2275 friend class HeapIterator; 2276 friend class IdleScavengeObserver; 2277 friend class IncrementalMarking; 2278 friend class IteratePromotedObjectsVisitor; 2279 friend class MarkCompactCollector; 2280 friend class MarkCompactMarkingVisitor; 2281 friend class NewSpace; 2282 friend class ObjectStatsCollector; 2283 friend class Page; 2284 friend class Scavenger; 2285 friend class StoreBuffer; 2286 friend class TestMemoryAllocatorScope; 2287 2288 // The allocator interface. 2289 friend class Factory; 2290 2291 // The Isolate constructs us. 2292 friend class Isolate; 2293 2294 // Used in cctest. 2295 friend class HeapTester; 2296 2297 DISALLOW_COPY_AND_ASSIGN(Heap); 2298 }; 2299 2300 2301 class HeapStats { 2302 public: 2303 static const int kStartMarker = 0xDECADE00; 2304 static const int kEndMarker = 0xDECADE01; 2305 2306 int* start_marker; // 0 2307 int* new_space_size; // 1 2308 int* new_space_capacity; // 2 2309 intptr_t* old_space_size; // 3 2310 intptr_t* old_space_capacity; // 4 2311 intptr_t* code_space_size; // 5 2312 intptr_t* code_space_capacity; // 6 2313 intptr_t* map_space_size; // 7 2314 intptr_t* map_space_capacity; // 8 2315 intptr_t* lo_space_size; // 9 2316 int* global_handle_count; // 10 2317 int* weak_global_handle_count; // 11 2318 int* pending_global_handle_count; // 12 2319 int* near_death_global_handle_count; // 13 2320 int* free_global_handle_count; // 14 2321 intptr_t* memory_allocator_size; // 15 2322 intptr_t* memory_allocator_capacity; // 16 2323 int* objects_per_type; // 17 2324 int* size_per_type; // 18 2325 int* os_error; // 19 2326 char* last_few_messages; // 20 2327 char* js_stacktrace; // 21 2328 int* end_marker; // 22 2329 }; 2330 2331 2332 class AlwaysAllocateScope { 2333 public: 2334 explicit inline AlwaysAllocateScope(Isolate* isolate); 2335 inline ~AlwaysAllocateScope(); 2336 2337 private: 2338 Heap* heap_; 2339 }; 2340 2341 2342 // Visitor class to verify interior pointers in spaces that do not contain 2343 // or care about intergenerational references. All heap object pointers have to 2344 // point into the heap to a location that has a map pointer at its first word. 2345 // Caveat: Heap::Contains is an approximation because it can return true for 2346 // objects in a heap space but above the allocation pointer. 2347 class VerifyPointersVisitor : public ObjectVisitor { 2348 public: 2349 inline void VisitPointers(Object** start, Object** end) override; 2350 }; 2351 2352 2353 // Verify that all objects are Smis. 2354 class VerifySmisVisitor : public ObjectVisitor { 2355 public: 2356 inline void VisitPointers(Object** start, Object** end) override; 2357 }; 2358 2359 2360 // Space iterator for iterating over all spaces of the heap. Returns each space 2361 // in turn, and null when it is done. 2362 class AllSpaces BASE_EMBEDDED { 2363 public: 2364 explicit AllSpaces(Heap* heap) : heap_(heap), counter_(FIRST_SPACE) {} 2365 Space* next(); 2366 2367 private: 2368 Heap* heap_; 2369 int counter_; 2370 }; 2371 2372 2373 // Space iterator for iterating over all old spaces of the heap: Old space 2374 // and code space. Returns each space in turn, and null when it is done. 2375 class OldSpaces BASE_EMBEDDED { 2376 public: 2377 explicit OldSpaces(Heap* heap) : heap_(heap), counter_(OLD_SPACE) {} 2378 OldSpace* next(); 2379 2380 private: 2381 Heap* heap_; 2382 int counter_; 2383 }; 2384 2385 2386 // Space iterator for iterating over all the paged spaces of the heap: Map 2387 // space, old space, code space and cell space. Returns 2388 // each space in turn, and null when it is done. 2389 class PagedSpaces BASE_EMBEDDED { 2390 public: 2391 explicit PagedSpaces(Heap* heap) : heap_(heap), counter_(OLD_SPACE) {} 2392 PagedSpace* next(); 2393 2394 private: 2395 Heap* heap_; 2396 int counter_; 2397 }; 2398 2399 2400 // Space iterator for iterating over all spaces of the heap. 2401 // For each space an object iterator is provided. The deallocation of the 2402 // returned object iterators is handled by the space iterator. 2403 class SpaceIterator : public Malloced { 2404 public: 2405 explicit SpaceIterator(Heap* heap); 2406 virtual ~SpaceIterator(); 2407 2408 bool has_next(); 2409 ObjectIterator* next(); 2410 2411 private: 2412 ObjectIterator* CreateIterator(); 2413 2414 Heap* heap_; 2415 int current_space_; // from enum AllocationSpace. 2416 ObjectIterator* iterator_; // object iterator for the current space. 2417 }; 2418 2419 2420 // A HeapIterator provides iteration over the whole heap. It 2421 // aggregates the specific iterators for the different spaces as 2422 // these can only iterate over one space only. 2423 // 2424 // HeapIterator ensures there is no allocation during its lifetime 2425 // (using an embedded DisallowHeapAllocation instance). 2426 // 2427 // HeapIterator can skip free list nodes (that is, de-allocated heap 2428 // objects that still remain in the heap). As implementation of free 2429 // nodes filtering uses GC marks, it can't be used during MS/MC GC 2430 // phases. Also, it is forbidden to interrupt iteration in this mode, 2431 // as this will leave heap objects marked (and thus, unusable). 2432 class HeapIterator BASE_EMBEDDED { 2433 public: 2434 enum HeapObjectsFiltering { kNoFiltering, kFilterUnreachable }; 2435 2436 explicit HeapIterator(Heap* heap, 2437 HeapObjectsFiltering filtering = kNoFiltering); 2438 ~HeapIterator(); 2439 2440 HeapObject* next(); 2441 2442 private: 2443 struct MakeHeapIterableHelper { 2444 explicit MakeHeapIterableHelper(Heap* heap) { heap->MakeHeapIterable(); } 2445 }; 2446 2447 HeapObject* NextObject(); 2448 2449 // The following two fields need to be declared in this order. Initialization 2450 // order guarantees that we first make the heap iterable (which may involve 2451 // allocations) and only then lock it down by not allowing further 2452 // allocations. 2453 MakeHeapIterableHelper make_heap_iterable_helper_; 2454 DisallowHeapAllocation no_heap_allocation_; 2455 2456 Heap* heap_; 2457 HeapObjectsFiltering filtering_; 2458 HeapObjectsFilter* filter_; 2459 // Space iterator for iterating all the spaces. 2460 SpaceIterator* space_iterator_; 2461 // Object iterator for the space currently being iterated. 2462 ObjectIterator* object_iterator_; 2463 }; 2464 2465 2466 // Cache for mapping (map, property name) into field offset. 2467 // Cleared at startup and prior to mark sweep collection. 2468 class KeyedLookupCache { 2469 public: 2470 // Lookup field offset for (map, name). If absent, -1 is returned. 2471 int Lookup(Handle<Map> map, Handle<Name> name); 2472 2473 // Update an element in the cache. 2474 void Update(Handle<Map> map, Handle<Name> name, int field_offset); 2475 2476 // Clear the cache. 2477 void Clear(); 2478 2479 static const int kLength = 256; 2480 static const int kCapacityMask = kLength - 1; 2481 static const int kMapHashShift = 5; 2482 static const int kHashMask = -4; // Zero the last two bits. 2483 static const int kEntriesPerBucket = 4; 2484 static const int kEntryLength = 2; 2485 static const int kMapIndex = 0; 2486 static const int kKeyIndex = 1; 2487 static const int kNotFound = -1; 2488 2489 // kEntriesPerBucket should be a power of 2. 2490 STATIC_ASSERT((kEntriesPerBucket & (kEntriesPerBucket - 1)) == 0); 2491 STATIC_ASSERT(kEntriesPerBucket == -kHashMask); 2492 2493 private: 2494 KeyedLookupCache() { 2495 for (int i = 0; i < kLength; ++i) { 2496 keys_[i].map = NULL; 2497 keys_[i].name = NULL; 2498 field_offsets_[i] = kNotFound; 2499 } 2500 } 2501 2502 static inline int Hash(Handle<Map> map, Handle<Name> name); 2503 2504 // Get the address of the keys and field_offsets arrays. Used in 2505 // generated code to perform cache lookups. 2506 Address keys_address() { return reinterpret_cast<Address>(&keys_); } 2507 2508 Address field_offsets_address() { 2509 return reinterpret_cast<Address>(&field_offsets_); 2510 } 2511 2512 struct Key { 2513 Map* map; 2514 Name* name; 2515 }; 2516 2517 Key keys_[kLength]; 2518 int field_offsets_[kLength]; 2519 2520 friend class ExternalReference; 2521 friend class Isolate; 2522 DISALLOW_COPY_AND_ASSIGN(KeyedLookupCache); 2523 }; 2524 2525 2526 // Cache for mapping (map, property name) into descriptor index. 2527 // The cache contains both positive and negative results. 2528 // Descriptor index equals kNotFound means the property is absent. 2529 // Cleared at startup and prior to any gc. 2530 class DescriptorLookupCache { 2531 public: 2532 // Lookup descriptor index for (map, name). 2533 // If absent, kAbsent is returned. 2534 inline int Lookup(Map* source, Name* name); 2535 2536 // Update an element in the cache. 2537 inline void Update(Map* source, Name* name, int result); 2538 2539 // Clear the cache. 2540 void Clear(); 2541 2542 static const int kAbsent = -2; 2543 2544 private: 2545 DescriptorLookupCache() { 2546 for (int i = 0; i < kLength; ++i) { 2547 keys_[i].source = NULL; 2548 keys_[i].name = NULL; 2549 results_[i] = kAbsent; 2550 } 2551 } 2552 2553 static inline int Hash(Object* source, Name* name); 2554 2555 static const int kLength = 64; 2556 struct Key { 2557 Map* source; 2558 Name* name; 2559 }; 2560 2561 Key keys_[kLength]; 2562 int results_[kLength]; 2563 2564 friend class Isolate; 2565 DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache); 2566 }; 2567 2568 2569 // Abstract base class for checking whether a weak object should be retained. 2570 class WeakObjectRetainer { 2571 public: 2572 virtual ~WeakObjectRetainer() {} 2573 2574 // Return whether this object should be retained. If NULL is returned the 2575 // object has no references. Otherwise the address of the retained object 2576 // should be returned as in some GC situations the object has been moved. 2577 virtual Object* RetainAs(Object* object) = 0; 2578 }; 2579 2580 2581 #ifdef DEBUG 2582 // Helper class for tracing paths to a search target Object from all roots. 2583 // The TracePathFrom() method can be used to trace paths from a specific 2584 // object to the search target object. 2585 class PathTracer : public ObjectVisitor { 2586 public: 2587 enum WhatToFind { 2588 FIND_ALL, // Will find all matches. 2589 FIND_FIRST // Will stop the search after first match. 2590 }; 2591 2592 // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject. 2593 static const int kMarkTag = 2; 2594 2595 // For the WhatToFind arg, if FIND_FIRST is specified, tracing will stop 2596 // after the first match. If FIND_ALL is specified, then tracing will be 2597 // done for all matches. 2598 PathTracer(Object* search_target, WhatToFind what_to_find, 2599 VisitMode visit_mode) 2600 : search_target_(search_target), 2601 found_target_(false), 2602 found_target_in_trace_(false), 2603 what_to_find_(what_to_find), 2604 visit_mode_(visit_mode), 2605 object_stack_(20), 2606 no_allocation() {} 2607 2608 void VisitPointers(Object** start, Object** end) override; 2609 2610 void Reset(); 2611 void TracePathFrom(Object** root); 2612 2613 bool found() const { return found_target_; } 2614 2615 static Object* const kAnyGlobalObject; 2616 2617 protected: 2618 class MarkVisitor; 2619 class UnmarkVisitor; 2620 2621 void MarkRecursively(Object** p, MarkVisitor* mark_visitor); 2622 void UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor); 2623 virtual void ProcessResults(); 2624 2625 Object* search_target_; 2626 bool found_target_; 2627 bool found_target_in_trace_; 2628 WhatToFind what_to_find_; 2629 VisitMode visit_mode_; 2630 List<Object*> object_stack_; 2631 2632 DisallowHeapAllocation no_allocation; // i.e. no gc allowed. 2633 2634 private: 2635 DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer); 2636 }; 2637 #endif // DEBUG 2638 2639 // ----------------------------------------------------------------------------- 2640 // Allows observation of allocations. 2641 class AllocationObserver { 2642 public: 2643 explicit AllocationObserver(intptr_t step_size) 2644 : step_size_(step_size), bytes_to_next_step_(step_size) { 2645 DCHECK(step_size >= kPointerSize); 2646 } 2647 virtual ~AllocationObserver() {} 2648 2649 // Called each time the observed space does an allocation step. This may be 2650 // more frequently than the step_size we are monitoring (e.g. when there are 2651 // multiple observers, or when page or space boundary is encountered.) 2652 void AllocationStep(int bytes_allocated, Address soon_object, size_t size) { 2653 bytes_to_next_step_ -= bytes_allocated; 2654 if (bytes_to_next_step_ <= 0) { 2655 Step(static_cast<int>(step_size_ - bytes_to_next_step_), soon_object, 2656 size); 2657 step_size_ = GetNextStepSize(); 2658 bytes_to_next_step_ = step_size_; 2659 } 2660 } 2661 2662 protected: 2663 intptr_t step_size() const { return step_size_; } 2664 intptr_t bytes_to_next_step() const { return bytes_to_next_step_; } 2665 2666 // Pure virtual method provided by the subclasses that gets called when at 2667 // least step_size bytes have been allocated. soon_object is the address just 2668 // allocated (but not yet initialized.) size is the size of the object as 2669 // requested (i.e. w/o the alignment fillers). Some complexities to be aware 2670 // of: 2671 // 1) soon_object will be nullptr in cases where we end up observing an 2672 // allocation that happens to be a filler space (e.g. page boundaries.) 2673 // 2) size is the requested size at the time of allocation. Right-trimming 2674 // may change the object size dynamically. 2675 // 3) soon_object may actually be the first object in an allocation-folding 2676 // group. In such a case size is the size of the group rather than the 2677 // first object. 2678 virtual void Step(int bytes_allocated, Address soon_object, size_t size) = 0; 2679 2680 // Subclasses can override this method to make step size dynamic. 2681 virtual intptr_t GetNextStepSize() { return step_size_; } 2682 2683 intptr_t step_size_; 2684 intptr_t bytes_to_next_step_; 2685 2686 private: 2687 friend class LargeObjectSpace; 2688 friend class NewSpace; 2689 friend class PagedSpace; 2690 DISALLOW_COPY_AND_ASSIGN(AllocationObserver); 2691 }; 2692 2693 } // namespace internal 2694 } // namespace v8 2695 2696 #endif // V8_HEAP_HEAP_H_ 2697
