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_H_ 6 #define V8_HEAP_H_ 7 8 #include <cmath> 9 10 #include "src/allocation.h" 11 #include "src/assert-scope.h" 12 #include "src/counters.h" 13 #include "src/globals.h" 14 #include "src/incremental-marking.h" 15 #include "src/list.h" 16 #include "src/mark-compact.h" 17 #include "src/objects-visiting.h" 18 #include "src/spaces.h" 19 #include "src/splay-tree-inl.h" 20 #include "src/store-buffer.h" 21 22 namespace v8 { 23 namespace internal { 24 25 // Defines all the roots in Heap. 26 #define STRONG_ROOT_LIST(V) \ 27 V(Map, byte_array_map, ByteArrayMap) \ 28 V(Map, free_space_map, FreeSpaceMap) \ 29 V(Map, one_pointer_filler_map, OnePointerFillerMap) \ 30 V(Map, two_pointer_filler_map, TwoPointerFillerMap) \ 31 /* Cluster the most popular ones in a few cache lines here at the top. */ \ 32 V(Smi, store_buffer_top, StoreBufferTop) \ 33 V(Oddball, undefined_value, UndefinedValue) \ 34 V(Oddball, the_hole_value, TheHoleValue) \ 35 V(Oddball, null_value, NullValue) \ 36 V(Oddball, true_value, TrueValue) \ 37 V(Oddball, false_value, FalseValue) \ 38 V(Oddball, uninitialized_value, UninitializedValue) \ 39 V(Oddball, exception, Exception) \ 40 V(Map, cell_map, CellMap) \ 41 V(Map, global_property_cell_map, GlobalPropertyCellMap) \ 42 V(Map, shared_function_info_map, SharedFunctionInfoMap) \ 43 V(Map, meta_map, MetaMap) \ 44 V(Map, heap_number_map, HeapNumberMap) \ 45 V(Map, native_context_map, NativeContextMap) \ 46 V(Map, fixed_array_map, FixedArrayMap) \ 47 V(Map, code_map, CodeMap) \ 48 V(Map, scope_info_map, ScopeInfoMap) \ 49 V(Map, fixed_cow_array_map, FixedCOWArrayMap) \ 50 V(Map, fixed_double_array_map, FixedDoubleArrayMap) \ 51 V(Map, constant_pool_array_map, ConstantPoolArrayMap) \ 52 V(Oddball, no_interceptor_result_sentinel, NoInterceptorResultSentinel) \ 53 V(Map, hash_table_map, HashTableMap) \ 54 V(Map, ordered_hash_table_map, OrderedHashTableMap) \ 55 V(FixedArray, empty_fixed_array, EmptyFixedArray) \ 56 V(ByteArray, empty_byte_array, EmptyByteArray) \ 57 V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray) \ 58 V(ConstantPoolArray, empty_constant_pool_array, EmptyConstantPoolArray) \ 59 V(Oddball, arguments_marker, ArgumentsMarker) \ 60 /* The roots above this line should be boring from a GC point of view. */ \ 61 /* This means they are never in new space and never on a page that is */ \ 62 /* being compacted. */ \ 63 V(FixedArray, number_string_cache, NumberStringCache) \ 64 V(Object, instanceof_cache_function, InstanceofCacheFunction) \ 65 V(Object, instanceof_cache_map, InstanceofCacheMap) \ 66 V(Object, instanceof_cache_answer, InstanceofCacheAnswer) \ 67 V(FixedArray, single_character_string_cache, SingleCharacterStringCache) \ 68 V(FixedArray, string_split_cache, StringSplitCache) \ 69 V(FixedArray, regexp_multiple_cache, RegExpMultipleCache) \ 70 V(Oddball, termination_exception, TerminationException) \ 71 V(Smi, hash_seed, HashSeed) \ 72 V(Map, symbol_map, SymbolMap) \ 73 V(Map, string_map, StringMap) \ 74 V(Map, ascii_string_map, AsciiStringMap) \ 75 V(Map, cons_string_map, ConsStringMap) \ 76 V(Map, cons_ascii_string_map, ConsAsciiStringMap) \ 77 V(Map, sliced_string_map, SlicedStringMap) \ 78 V(Map, sliced_ascii_string_map, SlicedAsciiStringMap) \ 79 V(Map, external_string_map, ExternalStringMap) \ 80 V(Map, \ 81 external_string_with_one_byte_data_map, \ 82 ExternalStringWithOneByteDataMap) \ 83 V(Map, external_ascii_string_map, ExternalAsciiStringMap) \ 84 V(Map, short_external_string_map, ShortExternalStringMap) \ 85 V(Map, \ 86 short_external_string_with_one_byte_data_map, \ 87 ShortExternalStringWithOneByteDataMap) \ 88 V(Map, internalized_string_map, InternalizedStringMap) \ 89 V(Map, ascii_internalized_string_map, AsciiInternalizedStringMap) \ 90 V(Map, \ 91 external_internalized_string_map, \ 92 ExternalInternalizedStringMap) \ 93 V(Map, \ 94 external_internalized_string_with_one_byte_data_map, \ 95 ExternalInternalizedStringWithOneByteDataMap) \ 96 V(Map, \ 97 external_ascii_internalized_string_map, \ 98 ExternalAsciiInternalizedStringMap) \ 99 V(Map, \ 100 short_external_internalized_string_map, \ 101 ShortExternalInternalizedStringMap) \ 102 V(Map, \ 103 short_external_internalized_string_with_one_byte_data_map, \ 104 ShortExternalInternalizedStringWithOneByteDataMap) \ 105 V(Map, \ 106 short_external_ascii_internalized_string_map, \ 107 ShortExternalAsciiInternalizedStringMap) \ 108 V(Map, short_external_ascii_string_map, ShortExternalAsciiStringMap) \ 109 V(Map, undetectable_string_map, UndetectableStringMap) \ 110 V(Map, undetectable_ascii_string_map, UndetectableAsciiStringMap) \ 111 V(Map, external_int8_array_map, ExternalInt8ArrayMap) \ 112 V(Map, external_uint8_array_map, ExternalUint8ArrayMap) \ 113 V(Map, external_int16_array_map, ExternalInt16ArrayMap) \ 114 V(Map, external_uint16_array_map, ExternalUint16ArrayMap) \ 115 V(Map, external_int32_array_map, ExternalInt32ArrayMap) \ 116 V(Map, external_uint32_array_map, ExternalUint32ArrayMap) \ 117 V(Map, external_float32_array_map, ExternalFloat32ArrayMap) \ 118 V(Map, external_float64_array_map, ExternalFloat64ArrayMap) \ 119 V(Map, external_uint8_clamped_array_map, ExternalUint8ClampedArrayMap) \ 120 V(ExternalArray, empty_external_int8_array, \ 121 EmptyExternalInt8Array) \ 122 V(ExternalArray, empty_external_uint8_array, \ 123 EmptyExternalUint8Array) \ 124 V(ExternalArray, empty_external_int16_array, EmptyExternalInt16Array) \ 125 V(ExternalArray, empty_external_uint16_array, \ 126 EmptyExternalUint16Array) \ 127 V(ExternalArray, empty_external_int32_array, EmptyExternalInt32Array) \ 128 V(ExternalArray, empty_external_uint32_array, \ 129 EmptyExternalUint32Array) \ 130 V(ExternalArray, empty_external_float32_array, EmptyExternalFloat32Array) \ 131 V(ExternalArray, empty_external_float64_array, EmptyExternalFloat64Array) \ 132 V(ExternalArray, empty_external_uint8_clamped_array, \ 133 EmptyExternalUint8ClampedArray) \ 134 V(Map, fixed_uint8_array_map, FixedUint8ArrayMap) \ 135 V(Map, fixed_int8_array_map, FixedInt8ArrayMap) \ 136 V(Map, fixed_uint16_array_map, FixedUint16ArrayMap) \ 137 V(Map, fixed_int16_array_map, FixedInt16ArrayMap) \ 138 V(Map, fixed_uint32_array_map, FixedUint32ArrayMap) \ 139 V(Map, fixed_int32_array_map, FixedInt32ArrayMap) \ 140 V(Map, fixed_float32_array_map, FixedFloat32ArrayMap) \ 141 V(Map, fixed_float64_array_map, FixedFloat64ArrayMap) \ 142 V(Map, fixed_uint8_clamped_array_map, FixedUint8ClampedArrayMap) \ 143 V(FixedTypedArrayBase, empty_fixed_uint8_array, EmptyFixedUint8Array) \ 144 V(FixedTypedArrayBase, empty_fixed_int8_array, EmptyFixedInt8Array) \ 145 V(FixedTypedArrayBase, empty_fixed_uint16_array, EmptyFixedUint16Array) \ 146 V(FixedTypedArrayBase, empty_fixed_int16_array, EmptyFixedInt16Array) \ 147 V(FixedTypedArrayBase, empty_fixed_uint32_array, EmptyFixedUint32Array) \ 148 V(FixedTypedArrayBase, empty_fixed_int32_array, EmptyFixedInt32Array) \ 149 V(FixedTypedArrayBase, empty_fixed_float32_array, EmptyFixedFloat32Array) \ 150 V(FixedTypedArrayBase, empty_fixed_float64_array, EmptyFixedFloat64Array) \ 151 V(FixedTypedArrayBase, empty_fixed_uint8_clamped_array, \ 152 EmptyFixedUint8ClampedArray) \ 153 V(Map, sloppy_arguments_elements_map, SloppyArgumentsElementsMap) \ 154 V(Map, function_context_map, FunctionContextMap) \ 155 V(Map, catch_context_map, CatchContextMap) \ 156 V(Map, with_context_map, WithContextMap) \ 157 V(Map, block_context_map, BlockContextMap) \ 158 V(Map, module_context_map, ModuleContextMap) \ 159 V(Map, global_context_map, GlobalContextMap) \ 160 V(Map, undefined_map, UndefinedMap) \ 161 V(Map, the_hole_map, TheHoleMap) \ 162 V(Map, null_map, NullMap) \ 163 V(Map, boolean_map, BooleanMap) \ 164 V(Map, uninitialized_map, UninitializedMap) \ 165 V(Map, arguments_marker_map, ArgumentsMarkerMap) \ 166 V(Map, no_interceptor_result_sentinel_map, NoInterceptorResultSentinelMap) \ 167 V(Map, exception_map, ExceptionMap) \ 168 V(Map, termination_exception_map, TerminationExceptionMap) \ 169 V(Map, message_object_map, JSMessageObjectMap) \ 170 V(Map, foreign_map, ForeignMap) \ 171 V(HeapNumber, nan_value, NanValue) \ 172 V(HeapNumber, infinity_value, InfinityValue) \ 173 V(HeapNumber, minus_zero_value, MinusZeroValue) \ 174 V(Map, neander_map, NeanderMap) \ 175 V(JSObject, message_listeners, MessageListeners) \ 176 V(UnseededNumberDictionary, code_stubs, CodeStubs) \ 177 V(UnseededNumberDictionary, non_monomorphic_cache, NonMonomorphicCache) \ 178 V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache) \ 179 V(Code, js_entry_code, JsEntryCode) \ 180 V(Code, js_construct_entry_code, JsConstructEntryCode) \ 181 V(FixedArray, natives_source_cache, NativesSourceCache) \ 182 V(Script, empty_script, EmptyScript) \ 183 V(NameDictionary, intrinsic_function_names, IntrinsicFunctionNames) \ 184 V(Cell, undefined_cell, UndefineCell) \ 185 V(JSObject, observation_state, ObservationState) \ 186 V(Map, external_map, ExternalMap) \ 187 V(Object, symbol_registry, SymbolRegistry) \ 188 V(Symbol, frozen_symbol, FrozenSymbol) \ 189 V(Symbol, nonexistent_symbol, NonExistentSymbol) \ 190 V(Symbol, elements_transition_symbol, ElementsTransitionSymbol) \ 191 V(SeededNumberDictionary, empty_slow_element_dictionary, \ 192 EmptySlowElementDictionary) \ 193 V(Symbol, observed_symbol, ObservedSymbol) \ 194 V(Symbol, uninitialized_symbol, UninitializedSymbol) \ 195 V(Symbol, megamorphic_symbol, MegamorphicSymbol) \ 196 V(FixedArray, materialized_objects, MaterializedObjects) \ 197 V(FixedArray, allocation_sites_scratchpad, AllocationSitesScratchpad) \ 198 V(FixedArray, microtask_queue, MicrotaskQueue) 199 200 // Entries in this list are limited to Smis and are not visited during GC. 201 #define SMI_ROOT_LIST(V) \ 202 V(Smi, stack_limit, StackLimit) \ 203 V(Smi, real_stack_limit, RealStackLimit) \ 204 V(Smi, last_script_id, LastScriptId) \ 205 V(Smi, arguments_adaptor_deopt_pc_offset, ArgumentsAdaptorDeoptPCOffset) \ 206 V(Smi, construct_stub_deopt_pc_offset, ConstructStubDeoptPCOffset) \ 207 V(Smi, getter_stub_deopt_pc_offset, GetterStubDeoptPCOffset) \ 208 V(Smi, setter_stub_deopt_pc_offset, SetterStubDeoptPCOffset) 209 210 #define ROOT_LIST(V) \ 211 STRONG_ROOT_LIST(V) \ 212 SMI_ROOT_LIST(V) \ 213 V(StringTable, string_table, StringTable) 214 215 // Heap roots that are known to be immortal immovable, for which we can safely 216 // skip write barriers. 217 #define IMMORTAL_IMMOVABLE_ROOT_LIST(V) \ 218 V(byte_array_map) \ 219 V(free_space_map) \ 220 V(one_pointer_filler_map) \ 221 V(two_pointer_filler_map) \ 222 V(undefined_value) \ 223 V(the_hole_value) \ 224 V(null_value) \ 225 V(true_value) \ 226 V(false_value) \ 227 V(uninitialized_value) \ 228 V(cell_map) \ 229 V(global_property_cell_map) \ 230 V(shared_function_info_map) \ 231 V(meta_map) \ 232 V(heap_number_map) \ 233 V(native_context_map) \ 234 V(fixed_array_map) \ 235 V(code_map) \ 236 V(scope_info_map) \ 237 V(fixed_cow_array_map) \ 238 V(fixed_double_array_map) \ 239 V(constant_pool_array_map) \ 240 V(no_interceptor_result_sentinel) \ 241 V(hash_table_map) \ 242 V(ordered_hash_table_map) \ 243 V(empty_fixed_array) \ 244 V(empty_byte_array) \ 245 V(empty_descriptor_array) \ 246 V(empty_constant_pool_array) \ 247 V(arguments_marker) \ 248 V(symbol_map) \ 249 V(sloppy_arguments_elements_map) \ 250 V(function_context_map) \ 251 V(catch_context_map) \ 252 V(with_context_map) \ 253 V(block_context_map) \ 254 V(module_context_map) \ 255 V(global_context_map) \ 256 V(undefined_map) \ 257 V(the_hole_map) \ 258 V(null_map) \ 259 V(boolean_map) \ 260 V(uninitialized_map) \ 261 V(message_object_map) \ 262 V(foreign_map) \ 263 V(neander_map) 264 265 #define INTERNALIZED_STRING_LIST(V) \ 266 V(Array_string, "Array") \ 267 V(Object_string, "Object") \ 268 V(proto_string, "__proto__") \ 269 V(arguments_string, "arguments") \ 270 V(Arguments_string, "Arguments") \ 271 V(call_string, "call") \ 272 V(apply_string, "apply") \ 273 V(caller_string, "caller") \ 274 V(boolean_string, "boolean") \ 275 V(Boolean_string, "Boolean") \ 276 V(callee_string, "callee") \ 277 V(constructor_string, "constructor") \ 278 V(dot_result_string, ".result") \ 279 V(dot_for_string, ".for.") \ 280 V(dot_iterable_string, ".iterable") \ 281 V(dot_iterator_string, ".iterator") \ 282 V(dot_generator_object_string, ".generator_object") \ 283 V(eval_string, "eval") \ 284 V(empty_string, "") \ 285 V(function_string, "function") \ 286 V(length_string, "length") \ 287 V(module_string, "module") \ 288 V(name_string, "name") \ 289 V(native_string, "native") \ 290 V(null_string, "null") \ 291 V(number_string, "number") \ 292 V(Number_string, "Number") \ 293 V(nan_string, "NaN") \ 294 V(RegExp_string, "RegExp") \ 295 V(source_string, "source") \ 296 V(global_string, "global") \ 297 V(ignore_case_string, "ignoreCase") \ 298 V(multiline_string, "multiline") \ 299 V(input_string, "input") \ 300 V(index_string, "index") \ 301 V(last_index_string, "lastIndex") \ 302 V(object_string, "object") \ 303 V(literals_string, "literals") \ 304 V(prototype_string, "prototype") \ 305 V(string_string, "string") \ 306 V(String_string, "String") \ 307 V(symbol_string, "symbol") \ 308 V(Symbol_string, "Symbol") \ 309 V(for_string, "for") \ 310 V(for_api_string, "for_api") \ 311 V(for_intern_string, "for_intern") \ 312 V(private_api_string, "private_api") \ 313 V(private_intern_string, "private_intern") \ 314 V(Date_string, "Date") \ 315 V(this_string, "this") \ 316 V(to_string_string, "toString") \ 317 V(char_at_string, "CharAt") \ 318 V(undefined_string, "undefined") \ 319 V(value_of_string, "valueOf") \ 320 V(stack_string, "stack") \ 321 V(toJSON_string, "toJSON") \ 322 V(InitializeVarGlobal_string, "InitializeVarGlobal") \ 323 V(InitializeConstGlobal_string, "InitializeConstGlobal") \ 324 V(KeyedLoadElementMonomorphic_string, \ 325 "KeyedLoadElementMonomorphic") \ 326 V(KeyedStoreElementMonomorphic_string, \ 327 "KeyedStoreElementMonomorphic") \ 328 V(stack_overflow_string, "kStackOverflowBoilerplate") \ 329 V(illegal_access_string, "illegal access") \ 330 V(get_string, "get") \ 331 V(set_string, "set") \ 332 V(map_field_string, "%map") \ 333 V(elements_field_string, "%elements") \ 334 V(length_field_string, "%length") \ 335 V(cell_value_string, "%cell_value") \ 336 V(function_class_string, "Function") \ 337 V(illegal_argument_string, "illegal argument") \ 338 V(MakeReferenceError_string, "MakeReferenceError") \ 339 V(MakeSyntaxError_string, "MakeSyntaxError") \ 340 V(MakeTypeError_string, "MakeTypeError") \ 341 V(unknown_label_string, "unknown_label") \ 342 V(space_string, " ") \ 343 V(exec_string, "exec") \ 344 V(zero_string, "0") \ 345 V(global_eval_string, "GlobalEval") \ 346 V(identity_hash_string, "v8::IdentityHash") \ 347 V(closure_string, "(closure)") \ 348 V(use_strict_string, "use strict") \ 349 V(dot_string, ".") \ 350 V(anonymous_function_string, "(anonymous function)") \ 351 V(compare_ic_string, "==") \ 352 V(strict_compare_ic_string, "===") \ 353 V(infinity_string, "Infinity") \ 354 V(minus_infinity_string, "-Infinity") \ 355 V(hidden_stack_trace_string, "v8::hidden_stack_trace") \ 356 V(query_colon_string, "(?:)") \ 357 V(Generator_string, "Generator") \ 358 V(throw_string, "throw") \ 359 V(done_string, "done") \ 360 V(value_string, "value") \ 361 V(next_string, "next") \ 362 V(byte_length_string, "byteLength") \ 363 V(byte_offset_string, "byteOffset") \ 364 V(buffer_string, "buffer") \ 365 V(intl_initialized_marker_string, "v8::intl_initialized_marker") \ 366 V(intl_impl_object_string, "v8::intl_object") 367 368 // Forward declarations. 369 class GCTracer; 370 class HeapStats; 371 class Isolate; 372 class WeakObjectRetainer; 373 374 375 typedef String* (*ExternalStringTableUpdaterCallback)(Heap* heap, 376 Object** pointer); 377 378 class StoreBufferRebuilder { 379 public: StoreBufferRebuilder(StoreBuffer * store_buffer)380 explicit StoreBufferRebuilder(StoreBuffer* store_buffer) 381 : store_buffer_(store_buffer) { 382 } 383 384 void Callback(MemoryChunk* page, StoreBufferEvent event); 385 386 private: 387 StoreBuffer* store_buffer_; 388 389 // We record in this variable how full the store buffer was when we started 390 // iterating over the current page, finding pointers to new space. If the 391 // store buffer overflows again we can exempt the page from the store buffer 392 // by rewinding to this point instead of having to search the store buffer. 393 Object*** start_of_current_page_; 394 // The current page we are scanning in the store buffer iterator. 395 MemoryChunk* current_page_; 396 }; 397 398 399 400 // A queue of objects promoted during scavenge. Each object is accompanied 401 // by it's size to avoid dereferencing a map pointer for scanning. 402 class PromotionQueue { 403 public: PromotionQueue(Heap * heap)404 explicit PromotionQueue(Heap* heap) 405 : front_(NULL), 406 rear_(NULL), 407 limit_(NULL), 408 emergency_stack_(0), 409 heap_(heap) { } 410 411 void Initialize(); 412 Destroy()413 void Destroy() { 414 ASSERT(is_empty()); 415 delete emergency_stack_; 416 emergency_stack_ = NULL; 417 } 418 419 inline void ActivateGuardIfOnTheSamePage(); 420 GetHeadPage()421 Page* GetHeadPage() { 422 return Page::FromAllocationTop(reinterpret_cast<Address>(rear_)); 423 } 424 SetNewLimit(Address limit)425 void SetNewLimit(Address limit) { 426 if (!guard_) { 427 return; 428 } 429 430 ASSERT(GetHeadPage() == Page::FromAllocationTop(limit)); 431 limit_ = reinterpret_cast<intptr_t*>(limit); 432 433 if (limit_ <= rear_) { 434 return; 435 } 436 437 RelocateQueueHead(); 438 } 439 is_empty()440 bool is_empty() { 441 return (front_ == rear_) && 442 (emergency_stack_ == NULL || emergency_stack_->length() == 0); 443 } 444 445 inline void insert(HeapObject* target, int size); 446 remove(HeapObject ** target,int * size)447 void remove(HeapObject** target, int* size) { 448 ASSERT(!is_empty()); 449 if (front_ == rear_) { 450 Entry e = emergency_stack_->RemoveLast(); 451 *target = e.obj_; 452 *size = e.size_; 453 return; 454 } 455 456 if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(front_))) { 457 NewSpacePage* front_page = 458 NewSpacePage::FromAddress(reinterpret_cast<Address>(front_)); 459 ASSERT(!front_page->prev_page()->is_anchor()); 460 front_ = 461 reinterpret_cast<intptr_t*>(front_page->prev_page()->area_end()); 462 } 463 *target = reinterpret_cast<HeapObject*>(*(--front_)); 464 *size = static_cast<int>(*(--front_)); 465 // Assert no underflow. 466 SemiSpace::AssertValidRange(reinterpret_cast<Address>(rear_), 467 reinterpret_cast<Address>(front_)); 468 } 469 470 private: 471 // The front of the queue is higher in the memory page chain than the rear. 472 intptr_t* front_; 473 intptr_t* rear_; 474 intptr_t* limit_; 475 476 bool guard_; 477 478 static const int kEntrySizeInWords = 2; 479 480 struct Entry { EntryEntry481 Entry(HeapObject* obj, int size) : obj_(obj), size_(size) { } 482 483 HeapObject* obj_; 484 int size_; 485 }; 486 List<Entry>* emergency_stack_; 487 488 Heap* heap_; 489 490 void RelocateQueueHead(); 491 492 DISALLOW_COPY_AND_ASSIGN(PromotionQueue); 493 }; 494 495 496 typedef void (*ScavengingCallback)(Map* map, 497 HeapObject** slot, 498 HeapObject* object); 499 500 501 // External strings table is a place where all external strings are 502 // registered. We need to keep track of such strings to properly 503 // finalize them. 504 class ExternalStringTable { 505 public: 506 // Registers an external string. 507 inline void AddString(String* string); 508 509 inline void Iterate(ObjectVisitor* v); 510 511 // Restores internal invariant and gets rid of collected strings. 512 // Must be called after each Iterate() that modified the strings. 513 void CleanUp(); 514 515 // Destroys all allocated memory. 516 void TearDown(); 517 518 private: ExternalStringTable(Heap * heap)519 explicit ExternalStringTable(Heap* heap) : heap_(heap) { } 520 521 friend class Heap; 522 523 inline void Verify(); 524 525 inline void AddOldString(String* string); 526 527 // Notifies the table that only a prefix of the new list is valid. 528 inline void ShrinkNewStrings(int position); 529 530 // To speed up scavenge collections new space string are kept 531 // separate from old space strings. 532 List<Object*> new_space_strings_; 533 List<Object*> old_space_strings_; 534 535 Heap* heap_; 536 537 DISALLOW_COPY_AND_ASSIGN(ExternalStringTable); 538 }; 539 540 541 enum ArrayStorageAllocationMode { 542 DONT_INITIALIZE_ARRAY_ELEMENTS, 543 INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE 544 }; 545 546 547 class Heap { 548 public: 549 // Configure heap size in MB before setup. Return false if the heap has been 550 // set up already. 551 bool ConfigureHeap(int max_semi_space_size, 552 int max_old_space_size, 553 int max_executable_size, 554 size_t code_range_size); 555 bool ConfigureHeapDefault(); 556 557 // Prepares the heap, setting up memory areas that are needed in the isolate 558 // without actually creating any objects. 559 bool SetUp(); 560 561 // Bootstraps the object heap with the core set of objects required to run. 562 // Returns whether it succeeded. 563 bool CreateHeapObjects(); 564 565 // Destroys all memory allocated by the heap. 566 void TearDown(); 567 568 // Set the stack limit in the roots_ array. Some architectures generate 569 // code that looks here, because it is faster than loading from the static 570 // jslimit_/real_jslimit_ variable in the StackGuard. 571 void SetStackLimits(); 572 573 // Returns whether SetUp has been called. 574 bool HasBeenSetUp(); 575 576 // Returns the maximum amount of memory reserved for the heap. For 577 // the young generation, we reserve 4 times the amount needed for a 578 // semi space. The young generation consists of two semi spaces and 579 // we reserve twice the amount needed for those in order to ensure 580 // that new space can be aligned to its size. MaxReserved()581 intptr_t MaxReserved() { 582 return 4 * reserved_semispace_size_ + max_old_generation_size_; 583 } MaxSemiSpaceSize()584 int MaxSemiSpaceSize() { return max_semi_space_size_; } ReservedSemiSpaceSize()585 int ReservedSemiSpaceSize() { return reserved_semispace_size_; } InitialSemiSpaceSize()586 int InitialSemiSpaceSize() { return initial_semispace_size_; } MaxOldGenerationSize()587 intptr_t MaxOldGenerationSize() { return max_old_generation_size_; } MaxExecutableSize()588 intptr_t MaxExecutableSize() { return max_executable_size_; } 589 590 // Returns the capacity of the heap in bytes w/o growing. Heap grows when 591 // more spaces are needed until it reaches the limit. 592 intptr_t Capacity(); 593 594 // Returns the amount of memory currently committed for the heap. 595 intptr_t CommittedMemory(); 596 597 // Returns the amount of executable memory currently committed for the heap. 598 intptr_t CommittedMemoryExecutable(); 599 600 // Returns the amount of phyical memory currently committed for the heap. 601 size_t CommittedPhysicalMemory(); 602 603 // Returns the maximum amount of memory ever committed for the heap. MaximumCommittedMemory()604 intptr_t MaximumCommittedMemory() { return maximum_committed_; } 605 606 // Updates the maximum committed memory for the heap. Should be called 607 // whenever a space grows. 608 void UpdateMaximumCommitted(); 609 610 // Returns the available bytes in space w/o growing. 611 // Heap doesn't guarantee that it can allocate an object that requires 612 // all available bytes. Check MaxHeapObjectSize() instead. 613 intptr_t Available(); 614 615 // Returns of size of all objects residing in the heap. 616 intptr_t SizeOfObjects(); 617 618 // Return the starting address and a mask for the new space. And-masking an 619 // address with the mask will result in the start address of the new space 620 // for all addresses in either semispace. NewSpaceStart()621 Address NewSpaceStart() { return new_space_.start(); } NewSpaceMask()622 uintptr_t NewSpaceMask() { return new_space_.mask(); } NewSpaceTop()623 Address NewSpaceTop() { return new_space_.top(); } 624 new_space()625 NewSpace* new_space() { return &new_space_; } old_pointer_space()626 OldSpace* old_pointer_space() { return old_pointer_space_; } old_data_space()627 OldSpace* old_data_space() { return old_data_space_; } code_space()628 OldSpace* code_space() { return code_space_; } map_space()629 MapSpace* map_space() { return map_space_; } cell_space()630 CellSpace* cell_space() { return cell_space_; } property_cell_space()631 PropertyCellSpace* property_cell_space() { 632 return property_cell_space_; 633 } lo_space()634 LargeObjectSpace* lo_space() { return lo_space_; } paged_space(int idx)635 PagedSpace* paged_space(int idx) { 636 switch (idx) { 637 case OLD_POINTER_SPACE: 638 return old_pointer_space(); 639 case OLD_DATA_SPACE: 640 return old_data_space(); 641 case MAP_SPACE: 642 return map_space(); 643 case CELL_SPACE: 644 return cell_space(); 645 case PROPERTY_CELL_SPACE: 646 return property_cell_space(); 647 case CODE_SPACE: 648 return code_space(); 649 case NEW_SPACE: 650 case LO_SPACE: 651 UNREACHABLE(); 652 } 653 return NULL; 654 } 655 always_allocate()656 bool always_allocate() { return always_allocate_scope_depth_ != 0; } always_allocate_scope_depth_address()657 Address always_allocate_scope_depth_address() { 658 return reinterpret_cast<Address>(&always_allocate_scope_depth_); 659 } linear_allocation()660 bool linear_allocation() { 661 return linear_allocation_scope_depth_ != 0; 662 } 663 NewSpaceAllocationTopAddress()664 Address* NewSpaceAllocationTopAddress() { 665 return new_space_.allocation_top_address(); 666 } NewSpaceAllocationLimitAddress()667 Address* NewSpaceAllocationLimitAddress() { 668 return new_space_.allocation_limit_address(); 669 } 670 OldPointerSpaceAllocationTopAddress()671 Address* OldPointerSpaceAllocationTopAddress() { 672 return old_pointer_space_->allocation_top_address(); 673 } OldPointerSpaceAllocationLimitAddress()674 Address* OldPointerSpaceAllocationLimitAddress() { 675 return old_pointer_space_->allocation_limit_address(); 676 } 677 OldDataSpaceAllocationTopAddress()678 Address* OldDataSpaceAllocationTopAddress() { 679 return old_data_space_->allocation_top_address(); 680 } OldDataSpaceAllocationLimitAddress()681 Address* OldDataSpaceAllocationLimitAddress() { 682 return old_data_space_->allocation_limit_address(); 683 } 684 685 // Returns a deep copy of the JavaScript object. 686 // Properties and elements are copied too. 687 // Optionally takes an AllocationSite to be appended in an AllocationMemento. 688 MUST_USE_RESULT AllocationResult CopyJSObject(JSObject* source, 689 AllocationSite* site = NULL); 690 691 // Clear the Instanceof cache (used when a prototype changes). 692 inline void ClearInstanceofCache(); 693 694 // Iterates the whole code space to clear all ICs of the given kind. 695 void ClearAllICsByKind(Code::Kind kind); 696 697 // For use during bootup. 698 void RepairFreeListsAfterBoot(); 699 700 template<typename T> 701 static inline bool IsOneByte(T t, int chars); 702 703 // Move len elements within a given array from src_index index to dst_index 704 // index. 705 void MoveElements(FixedArray* array, int dst_index, int src_index, int len); 706 707 // Sloppy mode arguments object size. 708 static const int kSloppyArgumentsObjectSize = 709 JSObject::kHeaderSize + 2 * kPointerSize; 710 // Strict mode arguments has no callee so it is smaller. 711 static const int kStrictArgumentsObjectSize = 712 JSObject::kHeaderSize + 1 * kPointerSize; 713 // Indicies for direct access into argument objects. 714 static const int kArgumentsLengthIndex = 0; 715 // callee is only valid in sloppy mode. 716 static const int kArgumentsCalleeIndex = 1; 717 718 // Finalizes an external string by deleting the associated external 719 // data and clearing the resource pointer. 720 inline void FinalizeExternalString(String* string); 721 722 // Initialize a filler object to keep the ability to iterate over the heap 723 // when shortening objects. 724 void CreateFillerObjectAt(Address addr, int size); 725 726 bool CanMoveObjectStart(HeapObject* object); 727 728 enum InvocationMode { FROM_GC, FROM_MUTATOR }; 729 730 // Maintain marking consistency for IncrementalMarking. 731 void AdjustLiveBytes(Address address, int by, InvocationMode mode); 732 733 // Converts the given boolean condition to JavaScript boolean value. 734 inline Object* ToBoolean(bool condition); 735 736 // Performs garbage collection operation. 737 // Returns whether there is a chance that another major GC could 738 // collect more garbage. 739 inline bool CollectGarbage( 740 AllocationSpace space, 741 const char* gc_reason = NULL, 742 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 743 744 static const int kNoGCFlags = 0; 745 static const int kSweepPreciselyMask = 1; 746 static const int kReduceMemoryFootprintMask = 2; 747 static const int kAbortIncrementalMarkingMask = 4; 748 749 // Making the heap iterable requires us to sweep precisely and abort any 750 // incremental marking as well. 751 static const int kMakeHeapIterableMask = 752 kSweepPreciselyMask | kAbortIncrementalMarkingMask; 753 754 // Performs a full garbage collection. If (flags & kMakeHeapIterableMask) is 755 // non-zero, then the slower precise sweeper is used, which leaves the heap 756 // in a state where we can iterate over the heap visiting all objects. 757 void CollectAllGarbage( 758 int flags, 759 const char* gc_reason = NULL, 760 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 761 762 // Last hope GC, should try to squeeze as much as possible. 763 void CollectAllAvailableGarbage(const char* gc_reason = NULL); 764 765 // Check whether the heap is currently iterable. 766 bool IsHeapIterable(); 767 768 // Notify the heap that a context has been disposed. 769 int NotifyContextDisposed(); 770 increment_scan_on_scavenge_pages()771 inline void increment_scan_on_scavenge_pages() { 772 scan_on_scavenge_pages_++; 773 if (FLAG_gc_verbose) { 774 PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_); 775 } 776 } 777 decrement_scan_on_scavenge_pages()778 inline void decrement_scan_on_scavenge_pages() { 779 scan_on_scavenge_pages_--; 780 if (FLAG_gc_verbose) { 781 PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_); 782 } 783 } 784 promotion_queue()785 PromotionQueue* promotion_queue() { return &promotion_queue_; } 786 787 void AddGCPrologueCallback(v8::Isolate::GCPrologueCallback callback, 788 GCType gc_type_filter, 789 bool pass_isolate = true); 790 void RemoveGCPrologueCallback(v8::Isolate::GCPrologueCallback callback); 791 792 void AddGCEpilogueCallback(v8::Isolate::GCEpilogueCallback callback, 793 GCType gc_type_filter, 794 bool pass_isolate = true); 795 void RemoveGCEpilogueCallback(v8::Isolate::GCEpilogueCallback callback); 796 797 // Heap root getters. We have versions with and without type::cast() here. 798 // You can't use type::cast during GC because the assert fails. 799 // TODO(1490): Try removing the unchecked accessors, now that GC marking does 800 // not corrupt the map. 801 #define ROOT_ACCESSOR(type, name, camel_name) \ 802 type* name() { \ 803 return type::cast(roots_[k##camel_name##RootIndex]); \ 804 } \ 805 type* raw_unchecked_##name() { \ 806 return reinterpret_cast<type*>(roots_[k##camel_name##RootIndex]); \ 807 } 808 ROOT_LIST(ROOT_ACCESSOR) 809 #undef ROOT_ACCESSOR 810 811 // Utility type maps 812 #define STRUCT_MAP_ACCESSOR(NAME, Name, name) \ 813 Map* name##_map() { \ 814 return Map::cast(roots_[k##Name##MapRootIndex]); \ 815 } STRUCT_LIST(STRUCT_MAP_ACCESSOR)816 STRUCT_LIST(STRUCT_MAP_ACCESSOR) 817 #undef STRUCT_MAP_ACCESSOR 818 819 #define STRING_ACCESSOR(name, str) String* name() { \ 820 return String::cast(roots_[k##name##RootIndex]); \ 821 } 822 INTERNALIZED_STRING_LIST(STRING_ACCESSOR) 823 #undef STRING_ACCESSOR 824 825 // The hidden_string is special because it is the empty string, but does 826 // not match the empty string. 827 String* hidden_string() { return hidden_string_; } 828 set_native_contexts_list(Object * object)829 void set_native_contexts_list(Object* object) { 830 native_contexts_list_ = object; 831 } native_contexts_list()832 Object* native_contexts_list() const { return native_contexts_list_; } 833 set_array_buffers_list(Object * object)834 void set_array_buffers_list(Object* object) { 835 array_buffers_list_ = object; 836 } array_buffers_list()837 Object* array_buffers_list() const { return array_buffers_list_; } 838 set_allocation_sites_list(Object * object)839 void set_allocation_sites_list(Object* object) { 840 allocation_sites_list_ = object; 841 } allocation_sites_list()842 Object* allocation_sites_list() { return allocation_sites_list_; } 843 844 // Used in CreateAllocationSiteStub and the (de)serializer. allocation_sites_list_address()845 Object** allocation_sites_list_address() { return &allocation_sites_list_; } 846 weak_object_to_code_table()847 Object* weak_object_to_code_table() { return weak_object_to_code_table_; } 848 set_encountered_weak_collections(Object * weak_collection)849 void set_encountered_weak_collections(Object* weak_collection) { 850 encountered_weak_collections_ = weak_collection; 851 } encountered_weak_collections()852 Object* encountered_weak_collections() const { 853 return encountered_weak_collections_; 854 } 855 856 // Number of mark-sweeps. ms_count()857 unsigned int ms_count() { return ms_count_; } 858 859 // Iterates over all roots in the heap. 860 void IterateRoots(ObjectVisitor* v, VisitMode mode); 861 // Iterates over all strong roots in the heap. 862 void IterateStrongRoots(ObjectVisitor* v, VisitMode mode); 863 // Iterates over entries in the smi roots list. Only interesting to the 864 // serializer/deserializer, since GC does not care about smis. 865 void IterateSmiRoots(ObjectVisitor* v); 866 // Iterates over all the other roots in the heap. 867 void IterateWeakRoots(ObjectVisitor* v, VisitMode mode); 868 869 // Iterate pointers to from semispace of new space found in memory interval 870 // from start to end. 871 void IterateAndMarkPointersToFromSpace(Address start, 872 Address end, 873 ObjectSlotCallback callback); 874 875 // Returns whether the object resides in new space. 876 inline bool InNewSpace(Object* object); 877 inline bool InNewSpace(Address address); 878 inline bool InNewSpacePage(Address address); 879 inline bool InFromSpace(Object* object); 880 inline bool InToSpace(Object* object); 881 882 // Returns whether the object resides in old pointer space. 883 inline bool InOldPointerSpace(Address address); 884 inline bool InOldPointerSpace(Object* object); 885 886 // Returns whether the object resides in old data space. 887 inline bool InOldDataSpace(Address address); 888 inline bool InOldDataSpace(Object* object); 889 890 // Checks whether an address/object in the heap (including auxiliary 891 // area and unused area). 892 bool Contains(Address addr); 893 bool Contains(HeapObject* value); 894 895 // Checks whether an address/object in a space. 896 // Currently used by tests, serialization and heap verification only. 897 bool InSpace(Address addr, AllocationSpace space); 898 bool InSpace(HeapObject* value, AllocationSpace space); 899 900 // Finds out which space an object should get promoted to based on its type. 901 inline OldSpace* TargetSpace(HeapObject* object); 902 static inline AllocationSpace TargetSpaceId(InstanceType type); 903 904 // Checks whether the given object is allowed to be migrated from it's 905 // current space into the given destination space. Used for debugging. 906 inline bool AllowedToBeMigrated(HeapObject* object, AllocationSpace dest); 907 908 // Sets the stub_cache_ (only used when expanding the dictionary). public_set_code_stubs(UnseededNumberDictionary * value)909 void public_set_code_stubs(UnseededNumberDictionary* value) { 910 roots_[kCodeStubsRootIndex] = value; 911 } 912 913 // Support for computing object sizes for old objects during GCs. Returns 914 // a function that is guaranteed to be safe for computing object sizes in 915 // the current GC phase. GcSafeSizeOfOldObjectFunction()916 HeapObjectCallback GcSafeSizeOfOldObjectFunction() { 917 return gc_safe_size_of_old_object_; 918 } 919 920 // Sets the non_monomorphic_cache_ (only used when expanding the dictionary). public_set_non_monomorphic_cache(UnseededNumberDictionary * value)921 void public_set_non_monomorphic_cache(UnseededNumberDictionary* value) { 922 roots_[kNonMonomorphicCacheRootIndex] = value; 923 } 924 public_set_empty_script(Script * script)925 void public_set_empty_script(Script* script) { 926 roots_[kEmptyScriptRootIndex] = script; 927 } 928 public_set_store_buffer_top(Address * top)929 void public_set_store_buffer_top(Address* top) { 930 roots_[kStoreBufferTopRootIndex] = reinterpret_cast<Smi*>(top); 931 } 932 public_set_materialized_objects(FixedArray * objects)933 void public_set_materialized_objects(FixedArray* objects) { 934 roots_[kMaterializedObjectsRootIndex] = objects; 935 } 936 937 // Generated code can embed this address to get access to the roots. roots_array_start()938 Object** roots_array_start() { return roots_; } 939 store_buffer_top_address()940 Address* store_buffer_top_address() { 941 return reinterpret_cast<Address*>(&roots_[kStoreBufferTopRootIndex]); 942 } 943 944 #ifdef VERIFY_HEAP 945 // Verify the heap is in its normal state before or after a GC. 946 void Verify(); 947 948 weak_embedded_objects_verification_enabled()949 bool weak_embedded_objects_verification_enabled() { 950 return no_weak_object_verification_scope_depth_ == 0; 951 } 952 #endif 953 954 #ifdef DEBUG 955 void Print(); 956 void PrintHandles(); 957 958 void OldPointerSpaceCheckStoreBuffer(); 959 void MapSpaceCheckStoreBuffer(); 960 void LargeObjectSpaceCheckStoreBuffer(); 961 962 // Report heap statistics. 963 void ReportHeapStatistics(const char* title); 964 void ReportCodeStatistics(const char* title); 965 #endif 966 967 // Zapping is needed for verify heap, and always done in debug builds. ShouldZapGarbage()968 static inline bool ShouldZapGarbage() { 969 #ifdef DEBUG 970 return true; 971 #else 972 #ifdef VERIFY_HEAP 973 return FLAG_verify_heap; 974 #else 975 return false; 976 #endif 977 #endif 978 } 979 980 // Print short heap statistics. 981 void PrintShortHeapStatistics(); 982 983 // Write barrier support for address[offset] = o. 984 INLINE(void RecordWrite(Address address, int offset)); 985 986 // Write barrier support for address[start : start + len[ = o. 987 INLINE(void RecordWrites(Address address, int start, int len)); 988 989 enum HeapState { NOT_IN_GC, SCAVENGE, MARK_COMPACT }; gc_state()990 inline HeapState gc_state() { return gc_state_; } 991 IsInGCPostProcessing()992 inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; } 993 994 #ifdef DEBUG set_allocation_timeout(int timeout)995 void set_allocation_timeout(int timeout) { 996 allocation_timeout_ = timeout; 997 } 998 999 void TracePathToObjectFrom(Object* target, Object* root); 1000 void TracePathToObject(Object* target); 1001 void TracePathToGlobal(); 1002 #endif 1003 1004 // Callback function passed to Heap::Iterate etc. Copies an object if 1005 // necessary, the object might be promoted to an old space. The caller must 1006 // ensure the precondition that the object is (a) a heap object and (b) in 1007 // the heap's from space. 1008 static inline void ScavengePointer(HeapObject** p); 1009 static inline void ScavengeObject(HeapObject** p, HeapObject* object); 1010 1011 enum ScratchpadSlotMode { 1012 IGNORE_SCRATCHPAD_SLOT, 1013 RECORD_SCRATCHPAD_SLOT 1014 }; 1015 1016 // If an object has an AllocationMemento trailing it, return it, otherwise 1017 // return NULL; 1018 inline AllocationMemento* FindAllocationMemento(HeapObject* object); 1019 1020 // An object may have an AllocationSite associated with it through a trailing 1021 // AllocationMemento. Its feedback should be updated when objects are found 1022 // in the heap. 1023 static inline void UpdateAllocationSiteFeedback( 1024 HeapObject* object, ScratchpadSlotMode mode); 1025 1026 // Support for partial snapshots. After calling this we have a linear 1027 // space to write objects in each space. 1028 void ReserveSpace(int *sizes, Address* addresses); 1029 1030 // 1031 // Support for the API. 1032 // 1033 1034 void CreateApiObjects(); 1035 PromotedTotalSize()1036 inline intptr_t PromotedTotalSize() { 1037 int64_t total = PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize(); 1038 if (total > kMaxInt) return static_cast<intptr_t>(kMaxInt); 1039 if (total < 0) return 0; 1040 return static_cast<intptr_t>(total); 1041 } 1042 OldGenerationSpaceAvailable()1043 inline intptr_t OldGenerationSpaceAvailable() { 1044 return old_generation_allocation_limit_ - PromotedTotalSize(); 1045 } 1046 OldGenerationCapacityAvailable()1047 inline intptr_t OldGenerationCapacityAvailable() { 1048 return max_old_generation_size_ - PromotedTotalSize(); 1049 } 1050 1051 static const intptr_t kMinimumOldGenerationAllocationLimit = 1052 8 * (Page::kPageSize > MB ? Page::kPageSize : MB); 1053 1054 static const int kPointerMultiplier = i::kPointerSize / 4; 1055 1056 // The new space size has to be a power of 2. Sizes are in MB. 1057 static const int kMaxSemiSpaceSizeLowMemoryDevice = 1058 1 * kPointerMultiplier; 1059 static const int kMaxSemiSpaceSizeMediumMemoryDevice = 1060 4 * kPointerMultiplier; 1061 static const int kMaxSemiSpaceSizeHighMemoryDevice = 1062 8 * kPointerMultiplier; 1063 static const int kMaxSemiSpaceSizeHugeMemoryDevice = 1064 8 * kPointerMultiplier; 1065 1066 // The old space size has to be a multiple of Page::kPageSize. 1067 // Sizes are in MB. 1068 static const int kMaxOldSpaceSizeLowMemoryDevice = 1069 128 * kPointerMultiplier; 1070 static const int kMaxOldSpaceSizeMediumMemoryDevice = 1071 256 * kPointerMultiplier; 1072 static const int kMaxOldSpaceSizeHighMemoryDevice = 1073 512 * kPointerMultiplier; 1074 static const int kMaxOldSpaceSizeHugeMemoryDevice = 1075 700 * kPointerMultiplier; 1076 1077 // The executable size has to be a multiple of Page::kPageSize. 1078 // Sizes are in MB. 1079 static const int kMaxExecutableSizeLowMemoryDevice = 96 * kPointerMultiplier; 1080 static const int kMaxExecutableSizeMediumMemoryDevice = 1081 192 * kPointerMultiplier; 1082 static const int kMaxExecutableSizeHighMemoryDevice = 1083 256 * kPointerMultiplier; 1084 static const int kMaxExecutableSizeHugeMemoryDevice = 1085 256 * kPointerMultiplier; 1086 1087 intptr_t OldGenerationAllocationLimit(intptr_t old_gen_size, 1088 int freed_global_handles); 1089 1090 // Indicates whether inline bump-pointer allocation has been disabled. inline_allocation_disabled()1091 bool inline_allocation_disabled() { return inline_allocation_disabled_; } 1092 1093 // Switch whether inline bump-pointer allocation should be used. 1094 void EnableInlineAllocation(); 1095 void DisableInlineAllocation(); 1096 1097 // Implements the corresponding V8 API function. 1098 bool IdleNotification(int hint); 1099 1100 // Declare all the root indices. This defines the root list order. 1101 enum RootListIndex { 1102 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex, 1103 STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION) 1104 #undef ROOT_INDEX_DECLARATION 1105 1106 #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex, 1107 INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION) 1108 #undef STRING_DECLARATION 1109 1110 // Utility type maps 1111 #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex, 1112 STRUCT_LIST(DECLARE_STRUCT_MAP) 1113 #undef DECLARE_STRUCT_MAP 1114 1115 kStringTableRootIndex, 1116 1117 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex, 1118 SMI_ROOT_LIST(ROOT_INDEX_DECLARATION) 1119 #undef ROOT_INDEX_DECLARATION 1120 1121 kRootListLength, 1122 kStrongRootListLength = kStringTableRootIndex, 1123 kSmiRootsStart = kStringTableRootIndex + 1 1124 }; 1125 1126 STATIC_ASSERT(kUndefinedValueRootIndex == 1127 Internals::kUndefinedValueRootIndex); 1128 STATIC_ASSERT(kNullValueRootIndex == Internals::kNullValueRootIndex); 1129 STATIC_ASSERT(kTrueValueRootIndex == Internals::kTrueValueRootIndex); 1130 STATIC_ASSERT(kFalseValueRootIndex == Internals::kFalseValueRootIndex); 1131 STATIC_ASSERT(kempty_stringRootIndex == Internals::kEmptyStringRootIndex); 1132 1133 // Generated code can embed direct references to non-writable roots if 1134 // they are in new space. 1135 static bool RootCanBeWrittenAfterInitialization(RootListIndex root_index); 1136 // Generated code can treat direct references to this root as constant. 1137 bool RootCanBeTreatedAsConstant(RootListIndex root_index); 1138 1139 Map* MapForFixedTypedArray(ExternalArrayType array_type); 1140 RootListIndex RootIndexForFixedTypedArray( 1141 ExternalArrayType array_type); 1142 1143 Map* MapForExternalArrayType(ExternalArrayType array_type); 1144 RootListIndex RootIndexForExternalArrayType( 1145 ExternalArrayType array_type); 1146 1147 RootListIndex RootIndexForEmptyExternalArray(ElementsKind kind); 1148 RootListIndex RootIndexForEmptyFixedTypedArray(ElementsKind kind); 1149 ExternalArray* EmptyExternalArrayForMap(Map* map); 1150 FixedTypedArrayBase* EmptyFixedTypedArrayForMap(Map* map); 1151 1152 void RecordStats(HeapStats* stats, bool take_snapshot = false); 1153 1154 // Copy block of memory from src to dst. Size of block should be aligned 1155 // by pointer size. 1156 static inline void CopyBlock(Address dst, Address src, int byte_size); 1157 1158 // Optimized version of memmove for blocks with pointer size aligned sizes and 1159 // pointer size aligned addresses. 1160 static inline void MoveBlock(Address dst, Address src, int byte_size); 1161 1162 // Check new space expansion criteria and expand semispaces if it was hit. 1163 void CheckNewSpaceExpansionCriteria(); 1164 IncrementPromotedObjectsSize(int object_size)1165 inline void IncrementPromotedObjectsSize(int object_size) { 1166 ASSERT(object_size > 0); 1167 promoted_objects_size_ += object_size; 1168 } 1169 IncrementSemiSpaceCopiedObjectSize(int object_size)1170 inline void IncrementSemiSpaceCopiedObjectSize(int object_size) { 1171 ASSERT(object_size > 0); 1172 semi_space_copied_object_size_ += object_size; 1173 } 1174 IncrementYoungSurvivorsCounter(int survived)1175 inline void IncrementYoungSurvivorsCounter(int survived) { 1176 ASSERT(survived >= 0); 1177 survived_since_last_expansion_ += survived; 1178 } 1179 NextGCIsLikelyToBeFull()1180 inline bool NextGCIsLikelyToBeFull() { 1181 if (FLAG_gc_global) return true; 1182 1183 if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true; 1184 1185 intptr_t adjusted_allocation_limit = 1186 old_generation_allocation_limit_ - new_space_.Capacity(); 1187 1188 if (PromotedTotalSize() >= adjusted_allocation_limit) return true; 1189 1190 return false; 1191 } 1192 1193 void UpdateNewSpaceReferencesInExternalStringTable( 1194 ExternalStringTableUpdaterCallback updater_func); 1195 1196 void UpdateReferencesInExternalStringTable( 1197 ExternalStringTableUpdaterCallback updater_func); 1198 1199 void ProcessWeakReferences(WeakObjectRetainer* retainer); 1200 1201 void VisitExternalResources(v8::ExternalResourceVisitor* visitor); 1202 1203 // Helper function that governs the promotion policy from new space to 1204 // old. If the object's old address lies below the new space's age 1205 // mark or if we've already filled the bottom 1/16th of the to space, 1206 // we try to promote this object. 1207 inline bool ShouldBePromoted(Address old_address, int object_size); 1208 1209 void ClearJSFunctionResultCaches(); 1210 1211 void ClearNormalizedMapCaches(); 1212 tracer()1213 GCTracer* tracer() { return tracer_; } 1214 1215 // Returns the size of objects residing in non new spaces. 1216 intptr_t PromotedSpaceSizeOfObjects(); 1217 total_regexp_code_generated()1218 double total_regexp_code_generated() { return total_regexp_code_generated_; } IncreaseTotalRegexpCodeGenerated(int size)1219 void IncreaseTotalRegexpCodeGenerated(int size) { 1220 total_regexp_code_generated_ += size; 1221 } 1222 IncrementCodeGeneratedBytes(bool is_crankshafted,int size)1223 void IncrementCodeGeneratedBytes(bool is_crankshafted, int size) { 1224 if (is_crankshafted) { 1225 crankshaft_codegen_bytes_generated_ += size; 1226 } else { 1227 full_codegen_bytes_generated_ += size; 1228 } 1229 } 1230 1231 // Returns maximum GC pause. get_max_gc_pause()1232 double get_max_gc_pause() { return max_gc_pause_; } 1233 1234 // Returns maximum size of objects alive after GC. get_max_alive_after_gc()1235 intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; } 1236 1237 // Returns minimal interval between two subsequent collections. get_min_in_mutator()1238 double get_min_in_mutator() { return min_in_mutator_; } 1239 1240 // TODO(hpayer): remove, should be handled by GCTracer AddMarkingTime(double marking_time)1241 void AddMarkingTime(double marking_time) { 1242 marking_time_ += marking_time; 1243 } 1244 marking_time()1245 double marking_time() const { 1246 return marking_time_; 1247 } 1248 1249 // TODO(hpayer): remove, should be handled by GCTracer AddSweepingTime(double sweeping_time)1250 void AddSweepingTime(double sweeping_time) { 1251 sweeping_time_ += sweeping_time; 1252 } 1253 sweeping_time()1254 double sweeping_time() const { 1255 return sweeping_time_; 1256 } 1257 mark_compact_collector()1258 MarkCompactCollector* mark_compact_collector() { 1259 return &mark_compact_collector_; 1260 } 1261 store_buffer()1262 StoreBuffer* store_buffer() { 1263 return &store_buffer_; 1264 } 1265 marking()1266 Marking* marking() { 1267 return &marking_; 1268 } 1269 incremental_marking()1270 IncrementalMarking* incremental_marking() { 1271 return &incremental_marking_; 1272 } 1273 external_string_table()1274 ExternalStringTable* external_string_table() { 1275 return &external_string_table_; 1276 } 1277 1278 // Returns the current sweep generation. sweep_generation()1279 int sweep_generation() { 1280 return sweep_generation_; 1281 } 1282 1283 inline Isolate* isolate(); 1284 1285 void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags); 1286 void CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags); 1287 1288 inline bool OldGenerationAllocationLimitReached(); 1289 DoScavengeObject(Map * map,HeapObject ** slot,HeapObject * obj)1290 inline void DoScavengeObject(Map* map, HeapObject** slot, HeapObject* obj) { 1291 scavenging_visitors_table_.GetVisitor(map)(map, slot, obj); 1292 } 1293 1294 void QueueMemoryChunkForFree(MemoryChunk* chunk); 1295 void FreeQueuedChunks(); 1296 gc_count()1297 int gc_count() const { return gc_count_; } 1298 1299 // Completely clear the Instanceof cache (to stop it keeping objects alive 1300 // around a GC). 1301 inline void CompletelyClearInstanceofCache(); 1302 1303 // The roots that have an index less than this are always in old space. 1304 static const int kOldSpaceRoots = 0x20; 1305 HashSeed()1306 uint32_t HashSeed() { 1307 uint32_t seed = static_cast<uint32_t>(hash_seed()->value()); 1308 ASSERT(FLAG_randomize_hashes || seed == 0); 1309 return seed; 1310 } 1311 SetArgumentsAdaptorDeoptPCOffset(int pc_offset)1312 void SetArgumentsAdaptorDeoptPCOffset(int pc_offset) { 1313 ASSERT(arguments_adaptor_deopt_pc_offset() == Smi::FromInt(0)); 1314 set_arguments_adaptor_deopt_pc_offset(Smi::FromInt(pc_offset)); 1315 } 1316 SetConstructStubDeoptPCOffset(int pc_offset)1317 void SetConstructStubDeoptPCOffset(int pc_offset) { 1318 ASSERT(construct_stub_deopt_pc_offset() == Smi::FromInt(0)); 1319 set_construct_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); 1320 } 1321 SetGetterStubDeoptPCOffset(int pc_offset)1322 void SetGetterStubDeoptPCOffset(int pc_offset) { 1323 ASSERT(getter_stub_deopt_pc_offset() == Smi::FromInt(0)); 1324 set_getter_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); 1325 } 1326 SetSetterStubDeoptPCOffset(int pc_offset)1327 void SetSetterStubDeoptPCOffset(int pc_offset) { 1328 ASSERT(setter_stub_deopt_pc_offset() == Smi::FromInt(0)); 1329 set_setter_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); 1330 } 1331 1332 // For post mortem debugging. 1333 void RememberUnmappedPage(Address page, bool compacted); 1334 1335 // Global inline caching age: it is incremented on some GCs after context 1336 // disposal. We use it to flush inline caches. global_ic_age()1337 int global_ic_age() { 1338 return global_ic_age_; 1339 } 1340 AgeInlineCaches()1341 void AgeInlineCaches() { 1342 global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax; 1343 } 1344 flush_monomorphic_ics()1345 bool flush_monomorphic_ics() { return flush_monomorphic_ics_; } 1346 amount_of_external_allocated_memory()1347 int64_t amount_of_external_allocated_memory() { 1348 return amount_of_external_allocated_memory_; 1349 } 1350 1351 void DeoptMarkedAllocationSites(); 1352 MaximumSizeScavenge()1353 bool MaximumSizeScavenge() { 1354 return maximum_size_scavenges_ > 0; 1355 } 1356 DeoptMaybeTenuredAllocationSites()1357 bool DeoptMaybeTenuredAllocationSites() { 1358 return new_space_.IsAtMaximumCapacity() && maximum_size_scavenges_ == 0; 1359 } 1360 1361 // ObjectStats are kept in two arrays, counts and sizes. Related stats are 1362 // stored in a contiguous linear buffer. Stats groups are stored one after 1363 // another. 1364 enum { 1365 FIRST_CODE_KIND_SUB_TYPE = LAST_TYPE + 1, 1366 FIRST_FIXED_ARRAY_SUB_TYPE = 1367 FIRST_CODE_KIND_SUB_TYPE + Code::NUMBER_OF_KINDS, 1368 FIRST_CODE_AGE_SUB_TYPE = 1369 FIRST_FIXED_ARRAY_SUB_TYPE + LAST_FIXED_ARRAY_SUB_TYPE + 1, 1370 OBJECT_STATS_COUNT = FIRST_CODE_AGE_SUB_TYPE + Code::kCodeAgeCount + 1 1371 }; 1372 RecordObjectStats(InstanceType type,size_t size)1373 void RecordObjectStats(InstanceType type, size_t size) { 1374 ASSERT(type <= LAST_TYPE); 1375 object_counts_[type]++; 1376 object_sizes_[type] += size; 1377 } 1378 RecordCodeSubTypeStats(int code_sub_type,int code_age,size_t size)1379 void RecordCodeSubTypeStats(int code_sub_type, int code_age, size_t size) { 1380 int code_sub_type_index = FIRST_CODE_KIND_SUB_TYPE + code_sub_type; 1381 int code_age_index = 1382 FIRST_CODE_AGE_SUB_TYPE + code_age - Code::kFirstCodeAge; 1383 ASSERT(code_sub_type_index >= FIRST_CODE_KIND_SUB_TYPE && 1384 code_sub_type_index < FIRST_CODE_AGE_SUB_TYPE); 1385 ASSERT(code_age_index >= FIRST_CODE_AGE_SUB_TYPE && 1386 code_age_index < OBJECT_STATS_COUNT); 1387 object_counts_[code_sub_type_index]++; 1388 object_sizes_[code_sub_type_index] += size; 1389 object_counts_[code_age_index]++; 1390 object_sizes_[code_age_index] += size; 1391 } 1392 RecordFixedArraySubTypeStats(int array_sub_type,size_t size)1393 void RecordFixedArraySubTypeStats(int array_sub_type, size_t size) { 1394 ASSERT(array_sub_type <= LAST_FIXED_ARRAY_SUB_TYPE); 1395 object_counts_[FIRST_FIXED_ARRAY_SUB_TYPE + array_sub_type]++; 1396 object_sizes_[FIRST_FIXED_ARRAY_SUB_TYPE + array_sub_type] += size; 1397 } 1398 1399 void CheckpointObjectStats(); 1400 1401 // We don't use a LockGuard here since we want to lock the heap 1402 // only when FLAG_concurrent_recompilation is true. 1403 class RelocationLock { 1404 public: RelocationLock(Heap * heap)1405 explicit RelocationLock(Heap* heap) : heap_(heap) { 1406 heap_->relocation_mutex_.Lock(); 1407 } 1408 1409 ~RelocationLock()1410 ~RelocationLock() { 1411 heap_->relocation_mutex_.Unlock(); 1412 } 1413 1414 private: 1415 Heap* heap_; 1416 }; 1417 1418 void AddWeakObjectToCodeDependency(Handle<Object> obj, 1419 Handle<DependentCode> dep); 1420 1421 DependentCode* LookupWeakObjectToCodeDependency(Handle<Object> obj); 1422 InitializeWeakObjectToCodeTable()1423 void InitializeWeakObjectToCodeTable() { 1424 set_weak_object_to_code_table(undefined_value()); 1425 } 1426 1427 void EnsureWeakObjectToCodeTable(); 1428 1429 static void FatalProcessOutOfMemory(const char* location, 1430 bool take_snapshot = false); 1431 1432 protected: 1433 // Methods made available to tests. 1434 1435 // Allocates a JS Map in the heap. 1436 MUST_USE_RESULT AllocationResult AllocateMap( 1437 InstanceType instance_type, 1438 int instance_size, 1439 ElementsKind elements_kind = TERMINAL_FAST_ELEMENTS_KIND); 1440 1441 // Allocates and initializes a new JavaScript object based on a 1442 // constructor. 1443 // If allocation_site is non-null, then a memento is emitted after the object 1444 // that points to the site. 1445 MUST_USE_RESULT AllocationResult AllocateJSObject( 1446 JSFunction* constructor, 1447 PretenureFlag pretenure = NOT_TENURED, 1448 AllocationSite* allocation_site = NULL); 1449 1450 // Allocates and initializes a new JavaScript object based on a map. 1451 // Passing an allocation site means that a memento will be created that 1452 // points to the site. 1453 MUST_USE_RESULT AllocationResult AllocateJSObjectFromMap( 1454 Map* map, 1455 PretenureFlag pretenure = NOT_TENURED, 1456 bool alloc_props = true, 1457 AllocationSite* allocation_site = NULL); 1458 1459 // Allocated a HeapNumber from value. 1460 MUST_USE_RESULT AllocationResult AllocateHeapNumber( 1461 double value, PretenureFlag pretenure = NOT_TENURED); 1462 1463 // Allocate a byte array of the specified length 1464 MUST_USE_RESULT AllocationResult AllocateByteArray( 1465 int length, 1466 PretenureFlag pretenure = NOT_TENURED); 1467 1468 // Allocates an arguments object - optionally with an elements array. 1469 MUST_USE_RESULT AllocationResult AllocateArgumentsObject( 1470 Object* callee, int length); 1471 1472 // Copy the code and scope info part of the code object, but insert 1473 // the provided data as the relocation information. 1474 MUST_USE_RESULT AllocationResult CopyCode(Code* code, 1475 Vector<byte> reloc_info); 1476 1477 MUST_USE_RESULT AllocationResult CopyCode(Code* code); 1478 1479 // Allocates a fixed array initialized with undefined values 1480 MUST_USE_RESULT AllocationResult AllocateFixedArray( 1481 int length, 1482 PretenureFlag pretenure = NOT_TENURED); 1483 1484 private: 1485 Heap(); 1486 1487 // The amount of external memory registered through the API kept alive 1488 // by global handles 1489 int64_t amount_of_external_allocated_memory_; 1490 1491 // Caches the amount of external memory registered at the last global gc. 1492 int64_t amount_of_external_allocated_memory_at_last_global_gc_; 1493 1494 // This can be calculated directly from a pointer to the heap; however, it is 1495 // more expedient to get at the isolate directly from within Heap methods. 1496 Isolate* isolate_; 1497 1498 Object* roots_[kRootListLength]; 1499 1500 size_t code_range_size_; 1501 int reserved_semispace_size_; 1502 int max_semi_space_size_; 1503 int initial_semispace_size_; 1504 intptr_t max_old_generation_size_; 1505 intptr_t max_executable_size_; 1506 intptr_t maximum_committed_; 1507 1508 // For keeping track of how much data has survived 1509 // scavenge since last new space expansion. 1510 int survived_since_last_expansion_; 1511 1512 // For keeping track on when to flush RegExp code. 1513 int sweep_generation_; 1514 1515 int always_allocate_scope_depth_; 1516 int linear_allocation_scope_depth_; 1517 1518 // For keeping track of context disposals. 1519 int contexts_disposed_; 1520 1521 int global_ic_age_; 1522 1523 bool flush_monomorphic_ics_; 1524 1525 int scan_on_scavenge_pages_; 1526 1527 NewSpace new_space_; 1528 OldSpace* old_pointer_space_; 1529 OldSpace* old_data_space_; 1530 OldSpace* code_space_; 1531 MapSpace* map_space_; 1532 CellSpace* cell_space_; 1533 PropertyCellSpace* property_cell_space_; 1534 LargeObjectSpace* lo_space_; 1535 HeapState gc_state_; 1536 int gc_post_processing_depth_; 1537 Address new_space_top_after_last_gc_; 1538 1539 // Returns the amount of external memory registered since last global gc. 1540 int64_t PromotedExternalMemorySize(); 1541 1542 unsigned int ms_count_; // how many mark-sweep collections happened 1543 unsigned int gc_count_; // how many gc happened 1544 1545 // For post mortem debugging. 1546 static const int kRememberedUnmappedPages = 128; 1547 int remembered_unmapped_pages_index_; 1548 Address remembered_unmapped_pages_[kRememberedUnmappedPages]; 1549 1550 // Total length of the strings we failed to flatten since the last GC. 1551 int unflattened_strings_length_; 1552 1553 #define ROOT_ACCESSOR(type, name, camel_name) \ 1554 inline void set_##name(type* value) { \ 1555 /* The deserializer makes use of the fact that these common roots are */ \ 1556 /* never in new space and never on a page that is being compacted. */ \ 1557 ASSERT(k##camel_name##RootIndex >= kOldSpaceRoots || !InNewSpace(value)); \ 1558 roots_[k##camel_name##RootIndex] = value; \ 1559 } 1560 ROOT_LIST(ROOT_ACCESSOR) 1561 #undef ROOT_ACCESSOR 1562 1563 #ifdef DEBUG 1564 // If the --gc-interval flag is set to a positive value, this 1565 // variable holds the value indicating the number of allocations 1566 // remain until the next failure and garbage collection. 1567 int allocation_timeout_; 1568 #endif // DEBUG 1569 1570 // Limit that triggers a global GC on the next (normally caused) GC. This 1571 // is checked when we have already decided to do a GC to help determine 1572 // which collector to invoke, before expanding a paged space in the old 1573 // generation and on every allocation in large object space. 1574 intptr_t old_generation_allocation_limit_; 1575 1576 // Indicates that an allocation has failed in the old generation since the 1577 // last GC. 1578 bool old_gen_exhausted_; 1579 1580 // Indicates that inline bump-pointer allocation has been globally disabled 1581 // for all spaces. This is used to disable allocations in generated code. 1582 bool inline_allocation_disabled_; 1583 1584 // Weak list heads, threaded through the objects. 1585 // List heads are initilized lazily and contain the undefined_value at start. 1586 Object* native_contexts_list_; 1587 Object* array_buffers_list_; 1588 Object* allocation_sites_list_; 1589 1590 // WeakHashTable that maps objects embedded in optimized code to dependent 1591 // code list. It is initilized lazily and contains the undefined_value at 1592 // start. 1593 Object* weak_object_to_code_table_; 1594 1595 // List of encountered weak collections (JSWeakMap and JSWeakSet) during 1596 // marking. It is initialized during marking, destroyed after marking and 1597 // contains Smi(0) while marking is not active. 1598 Object* encountered_weak_collections_; 1599 1600 StoreBufferRebuilder store_buffer_rebuilder_; 1601 1602 struct StringTypeTable { 1603 InstanceType type; 1604 int size; 1605 RootListIndex index; 1606 }; 1607 1608 struct ConstantStringTable { 1609 const char* contents; 1610 RootListIndex index; 1611 }; 1612 1613 struct StructTable { 1614 InstanceType type; 1615 int size; 1616 RootListIndex index; 1617 }; 1618 1619 static const StringTypeTable string_type_table[]; 1620 static const ConstantStringTable constant_string_table[]; 1621 static const StructTable struct_table[]; 1622 1623 // The special hidden string which is an empty string, but does not match 1624 // any string when looked up in properties. 1625 String* hidden_string_; 1626 1627 // GC callback function, called before and after mark-compact GC. 1628 // Allocations in the callback function are disallowed. 1629 struct GCPrologueCallbackPair { GCPrologueCallbackPairGCPrologueCallbackPair1630 GCPrologueCallbackPair(v8::Isolate::GCPrologueCallback callback, 1631 GCType gc_type, 1632 bool pass_isolate) 1633 : callback(callback), gc_type(gc_type), pass_isolate_(pass_isolate) { 1634 } 1635 bool operator==(const GCPrologueCallbackPair& pair) const { 1636 return pair.callback == callback; 1637 } 1638 v8::Isolate::GCPrologueCallback callback; 1639 GCType gc_type; 1640 // TODO(dcarney): remove variable 1641 bool pass_isolate_; 1642 }; 1643 List<GCPrologueCallbackPair> gc_prologue_callbacks_; 1644 1645 struct GCEpilogueCallbackPair { GCEpilogueCallbackPairGCEpilogueCallbackPair1646 GCEpilogueCallbackPair(v8::Isolate::GCPrologueCallback callback, 1647 GCType gc_type, 1648 bool pass_isolate) 1649 : callback(callback), gc_type(gc_type), pass_isolate_(pass_isolate) { 1650 } 1651 bool operator==(const GCEpilogueCallbackPair& pair) const { 1652 return pair.callback == callback; 1653 } 1654 v8::Isolate::GCPrologueCallback callback; 1655 GCType gc_type; 1656 // TODO(dcarney): remove variable 1657 bool pass_isolate_; 1658 }; 1659 List<GCEpilogueCallbackPair> gc_epilogue_callbacks_; 1660 1661 // Support for computing object sizes during GC. 1662 HeapObjectCallback gc_safe_size_of_old_object_; 1663 static int GcSafeSizeOfOldObject(HeapObject* object); 1664 1665 // Update the GC state. Called from the mark-compact collector. MarkMapPointersAsEncoded(bool encoded)1666 void MarkMapPointersAsEncoded(bool encoded) { 1667 ASSERT(!encoded); 1668 gc_safe_size_of_old_object_ = &GcSafeSizeOfOldObject; 1669 } 1670 1671 // Code that should be run before and after each GC. Includes some 1672 // reporting/verification activities when compiled with DEBUG set. 1673 void GarbageCollectionPrologue(); 1674 void GarbageCollectionEpilogue(); 1675 1676 // Pretenuring decisions are made based on feedback collected during new 1677 // space evacuation. Note that between feedback collection and calling this 1678 // method object in old space must not move. 1679 // Right now we only process pretenuring feedback in high promotion mode. 1680 void ProcessPretenuringFeedback(); 1681 1682 // Checks whether a global GC is necessary 1683 GarbageCollector SelectGarbageCollector(AllocationSpace space, 1684 const char** reason); 1685 1686 // Make sure there is a filler value behind the top of the new space 1687 // so that the GC does not confuse some unintialized/stale memory 1688 // with the allocation memento of the object at the top 1689 void EnsureFillerObjectAtTop(); 1690 1691 // Ensure that we have swept all spaces in such a way that we can iterate 1692 // over all objects. May cause a GC. 1693 void MakeHeapIterable(); 1694 1695 // Performs garbage collection operation. 1696 // Returns whether there is a chance that another major GC could 1697 // collect more garbage. 1698 bool CollectGarbage( 1699 GarbageCollector collector, 1700 const char* gc_reason, 1701 const char* collector_reason, 1702 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1703 1704 // Performs garbage collection 1705 // Returns whether there is a chance another major GC could 1706 // collect more garbage. 1707 bool PerformGarbageCollection( 1708 GarbageCollector collector, 1709 GCTracer* tracer, 1710 const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags); 1711 1712 inline void UpdateOldSpaceLimits(); 1713 1714 // Selects the proper allocation space depending on the given object 1715 // size, pretenuring decision, and preferred old-space. SelectSpace(int object_size,AllocationSpace preferred_old_space,PretenureFlag pretenure)1716 static AllocationSpace SelectSpace(int object_size, 1717 AllocationSpace preferred_old_space, 1718 PretenureFlag pretenure) { 1719 ASSERT(preferred_old_space == OLD_POINTER_SPACE || 1720 preferred_old_space == OLD_DATA_SPACE); 1721 if (object_size > Page::kMaxRegularHeapObjectSize) return LO_SPACE; 1722 return (pretenure == TENURED) ? preferred_old_space : NEW_SPACE; 1723 } 1724 1725 // Allocate an uninitialized object. The memory is non-executable if the 1726 // hardware and OS allow. This is the single choke-point for allocations 1727 // performed by the runtime and should not be bypassed (to extend this to 1728 // inlined allocations, use the Heap::DisableInlineAllocation() support). 1729 MUST_USE_RESULT inline AllocationResult AllocateRaw( 1730 int size_in_bytes, 1731 AllocationSpace space, 1732 AllocationSpace retry_space); 1733 1734 // Allocates a heap object based on the map. 1735 MUST_USE_RESULT AllocationResult Allocate( 1736 Map* map, 1737 AllocationSpace space, 1738 AllocationSite* allocation_site = NULL); 1739 1740 // Allocates a partial map for bootstrapping. 1741 MUST_USE_RESULT AllocationResult AllocatePartialMap( 1742 InstanceType instance_type, 1743 int instance_size); 1744 1745 // Initializes a JSObject based on its map. 1746 void InitializeJSObjectFromMap(JSObject* obj, 1747 FixedArray* properties, 1748 Map* map); 1749 void InitializeAllocationMemento(AllocationMemento* memento, 1750 AllocationSite* allocation_site); 1751 1752 // Allocate a block of memory in the given space (filled with a filler). 1753 // Used as a fall-back for generated code when the space is full. 1754 MUST_USE_RESULT AllocationResult AllocateFillerObject(int size, 1755 bool double_align, 1756 AllocationSpace space); 1757 1758 // Allocate an uninitialized fixed array. 1759 MUST_USE_RESULT AllocationResult AllocateRawFixedArray( 1760 int length, PretenureFlag pretenure); 1761 1762 // Allocate an uninitialized fixed double array. 1763 MUST_USE_RESULT AllocationResult AllocateRawFixedDoubleArray( 1764 int length, PretenureFlag pretenure); 1765 1766 // Allocate an initialized fixed array with the given filler value. 1767 MUST_USE_RESULT AllocationResult AllocateFixedArrayWithFiller( 1768 int length, PretenureFlag pretenure, Object* filler); 1769 1770 // Allocate and partially initializes a String. There are two String 1771 // encodings: ASCII and two byte. These functions allocate a string of the 1772 // given length and set its map and length fields. The characters of the 1773 // string are uninitialized. 1774 MUST_USE_RESULT AllocationResult AllocateRawOneByteString( 1775 int length, PretenureFlag pretenure); 1776 MUST_USE_RESULT AllocationResult AllocateRawTwoByteString( 1777 int length, PretenureFlag pretenure); 1778 1779 bool CreateInitialMaps(); 1780 void CreateInitialObjects(); 1781 1782 // Allocates an internalized string in old space based on the character 1783 // stream. 1784 MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringFromUtf8( 1785 Vector<const char> str, 1786 int chars, 1787 uint32_t hash_field); 1788 1789 MUST_USE_RESULT inline AllocationResult AllocateOneByteInternalizedString( 1790 Vector<const uint8_t> str, 1791 uint32_t hash_field); 1792 1793 MUST_USE_RESULT inline AllocationResult AllocateTwoByteInternalizedString( 1794 Vector<const uc16> str, 1795 uint32_t hash_field); 1796 1797 template<bool is_one_byte, typename T> 1798 MUST_USE_RESULT AllocationResult AllocateInternalizedStringImpl( 1799 T t, int chars, uint32_t hash_field); 1800 1801 template<typename T> 1802 MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringImpl( 1803 T t, int chars, uint32_t hash_field); 1804 1805 // Allocates an uninitialized fixed array. It must be filled by the caller. 1806 MUST_USE_RESULT AllocationResult AllocateUninitializedFixedArray(int length); 1807 1808 // Make a copy of src and return it. Returns 1809 // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. 1810 MUST_USE_RESULT inline AllocationResult CopyFixedArray(FixedArray* src); 1811 1812 // Make a copy of src, set the map, and return the copy. Returns 1813 // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. 1814 MUST_USE_RESULT AllocationResult CopyFixedArrayWithMap(FixedArray* src, 1815 Map* map); 1816 1817 // Make a copy of src and return it. Returns 1818 // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. 1819 MUST_USE_RESULT inline AllocationResult CopyFixedDoubleArray( 1820 FixedDoubleArray* src); 1821 1822 // Make a copy of src and return it. Returns 1823 // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. 1824 MUST_USE_RESULT inline AllocationResult CopyConstantPoolArray( 1825 ConstantPoolArray* src); 1826 1827 1828 // Computes a single character string where the character has code. 1829 // A cache is used for ASCII codes. 1830 MUST_USE_RESULT AllocationResult LookupSingleCharacterStringFromCode( 1831 uint16_t code); 1832 1833 // Allocate a symbol in old space. 1834 MUST_USE_RESULT AllocationResult AllocateSymbol(); 1835 1836 // Make a copy of src, set the map, and return the copy. 1837 MUST_USE_RESULT AllocationResult CopyConstantPoolArrayWithMap( 1838 ConstantPoolArray* src, Map* map); 1839 1840 MUST_USE_RESULT AllocationResult AllocateConstantPoolArray( 1841 const ConstantPoolArray::NumberOfEntries& small); 1842 1843 MUST_USE_RESULT AllocationResult AllocateExtendedConstantPoolArray( 1844 const ConstantPoolArray::NumberOfEntries& small, 1845 const ConstantPoolArray::NumberOfEntries& extended); 1846 1847 // Allocates an external array of the specified length and type. 1848 MUST_USE_RESULT AllocationResult AllocateExternalArray( 1849 int length, 1850 ExternalArrayType array_type, 1851 void* external_pointer, 1852 PretenureFlag pretenure); 1853 1854 // Allocates a fixed typed array of the specified length and type. 1855 MUST_USE_RESULT AllocationResult AllocateFixedTypedArray( 1856 int length, 1857 ExternalArrayType array_type, 1858 PretenureFlag pretenure); 1859 1860 // Make a copy of src and return it. 1861 MUST_USE_RESULT AllocationResult CopyAndTenureFixedCOWArray(FixedArray* src); 1862 1863 // Make a copy of src, set the map, and return the copy. 1864 MUST_USE_RESULT AllocationResult CopyFixedDoubleArrayWithMap( 1865 FixedDoubleArray* src, Map* map); 1866 1867 // Allocates a fixed double array with uninitialized values. Returns 1868 MUST_USE_RESULT AllocationResult AllocateUninitializedFixedDoubleArray( 1869 int length, 1870 PretenureFlag pretenure = NOT_TENURED); 1871 1872 // These five Create*EntryStub functions are here and forced to not be inlined 1873 // because of a gcc-4.4 bug that assigns wrong vtable entries. 1874 NO_INLINE(void CreateJSEntryStub()); 1875 NO_INLINE(void CreateJSConstructEntryStub()); 1876 1877 void CreateFixedStubs(); 1878 1879 // Allocate empty fixed array. 1880 MUST_USE_RESULT AllocationResult AllocateEmptyFixedArray(); 1881 1882 // Allocate empty external array of given type. 1883 MUST_USE_RESULT AllocationResult AllocateEmptyExternalArray( 1884 ExternalArrayType array_type); 1885 1886 // Allocate empty fixed typed array of given type. 1887 MUST_USE_RESULT AllocationResult AllocateEmptyFixedTypedArray( 1888 ExternalArrayType array_type); 1889 1890 // Allocate empty constant pool array. 1891 MUST_USE_RESULT AllocationResult AllocateEmptyConstantPoolArray(); 1892 1893 // Allocate a tenured simple cell. 1894 MUST_USE_RESULT AllocationResult AllocateCell(Object* value); 1895 1896 // Allocate a tenured JS global property cell initialized with the hole. 1897 MUST_USE_RESULT AllocationResult AllocatePropertyCell(); 1898 1899 // Allocates a new utility object in the old generation. 1900 MUST_USE_RESULT AllocationResult AllocateStruct(InstanceType type); 1901 1902 // Allocates a new foreign object. 1903 MUST_USE_RESULT AllocationResult AllocateForeign( 1904 Address address, PretenureFlag pretenure = NOT_TENURED); 1905 1906 MUST_USE_RESULT AllocationResult AllocateCode(int object_size, 1907 bool immovable); 1908 1909 MUST_USE_RESULT AllocationResult InternalizeStringWithKey(HashTableKey* key); 1910 1911 MUST_USE_RESULT AllocationResult InternalizeString(String* str); 1912 1913 // Performs a minor collection in new generation. 1914 void Scavenge(); 1915 1916 // Commits from space if it is uncommitted. 1917 void EnsureFromSpaceIsCommitted(); 1918 1919 // Uncommit unused semi space. UncommitFromSpace()1920 bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); } 1921 1922 // Fill in bogus values in from space 1923 void ZapFromSpace(); 1924 1925 static String* UpdateNewSpaceReferenceInExternalStringTableEntry( 1926 Heap* heap, 1927 Object** pointer); 1928 1929 Address DoScavenge(ObjectVisitor* scavenge_visitor, Address new_space_front); 1930 static void ScavengeStoreBufferCallback(Heap* heap, 1931 MemoryChunk* page, 1932 StoreBufferEvent event); 1933 1934 // Performs a major collection in the whole heap. 1935 void MarkCompact(GCTracer* tracer); 1936 1937 // Code to be run before and after mark-compact. 1938 void MarkCompactPrologue(); 1939 1940 void ProcessNativeContexts(WeakObjectRetainer* retainer); 1941 void ProcessArrayBuffers(WeakObjectRetainer* retainer); 1942 void ProcessAllocationSites(WeakObjectRetainer* retainer); 1943 1944 // Deopts all code that contains allocation instruction which are tenured or 1945 // not tenured. Moreover it clears the pretenuring allocation site statistics. 1946 void ResetAllAllocationSitesDependentCode(PretenureFlag flag); 1947 1948 // Evaluates local pretenuring for the old space and calls 1949 // ResetAllTenuredAllocationSitesDependentCode if too many objects died in 1950 // the old space. 1951 void EvaluateOldSpaceLocalPretenuring(uint64_t size_of_objects_before_gc); 1952 1953 // Called on heap tear-down. 1954 void TearDownArrayBuffers(); 1955 1956 // Record statistics before and after garbage collection. 1957 void ReportStatisticsBeforeGC(); 1958 void ReportStatisticsAfterGC(); 1959 1960 // Slow part of scavenge object. 1961 static void ScavengeObjectSlow(HeapObject** p, HeapObject* object); 1962 1963 // Total RegExp code ever generated 1964 double total_regexp_code_generated_; 1965 1966 GCTracer* tracer_; 1967 1968 // Creates and installs the full-sized number string cache. 1969 int FullSizeNumberStringCacheLength(); 1970 // Flush the number to string cache. 1971 void FlushNumberStringCache(); 1972 1973 // Sets used allocation sites entries to undefined. 1974 void FlushAllocationSitesScratchpad(); 1975 1976 // Initializes the allocation sites scratchpad with undefined values. 1977 void InitializeAllocationSitesScratchpad(); 1978 1979 // Adds an allocation site to the scratchpad if there is space left. 1980 void AddAllocationSiteToScratchpad(AllocationSite* site, 1981 ScratchpadSlotMode mode); 1982 1983 void UpdateSurvivalStatistics(int start_new_space_size); 1984 1985 static const int kYoungSurvivalRateHighThreshold = 90; 1986 static const int kYoungSurvivalRateAllowedDeviation = 15; 1987 1988 static const int kOldSurvivalRateLowThreshold = 10; 1989 1990 int high_survival_rate_period_length_; 1991 intptr_t promoted_objects_size_; 1992 double promotion_rate_; 1993 intptr_t semi_space_copied_object_size_; 1994 double semi_space_copied_rate_; 1995 1996 // This is the pretenuring trigger for allocation sites that are in maybe 1997 // tenure state. When we switched to the maximum new space size we deoptimize 1998 // the code that belongs to the allocation site and derive the lifetime 1999 // of the allocation site. 2000 unsigned int maximum_size_scavenges_; 2001 2002 // TODO(hpayer): Allocation site pretenuring may make this method obsolete. 2003 // Re-visit incremental marking heuristics. IsHighSurvivalRate()2004 bool IsHighSurvivalRate() { 2005 return high_survival_rate_period_length_ > 0; 2006 } 2007 2008 void SelectScavengingVisitorsTable(); 2009 StartIdleRound()2010 void StartIdleRound() { 2011 mark_sweeps_since_idle_round_started_ = 0; 2012 } 2013 FinishIdleRound()2014 void FinishIdleRound() { 2015 mark_sweeps_since_idle_round_started_ = kMaxMarkSweepsInIdleRound; 2016 scavenges_since_last_idle_round_ = 0; 2017 } 2018 EnoughGarbageSinceLastIdleRound()2019 bool EnoughGarbageSinceLastIdleRound() { 2020 return (scavenges_since_last_idle_round_ >= kIdleScavengeThreshold); 2021 } 2022 2023 // Estimates how many milliseconds a Mark-Sweep would take to complete. 2024 // In idle notification handler we assume that this function will return: 2025 // - a number less than 10 for small heaps, which are less than 8Mb. 2026 // - a number greater than 10 for large heaps, which are greater than 32Mb. TimeMarkSweepWouldTakeInMs()2027 int TimeMarkSweepWouldTakeInMs() { 2028 // Rough estimate of how many megabytes of heap can be processed in 1 ms. 2029 static const int kMbPerMs = 2; 2030 2031 int heap_size_mb = static_cast<int>(SizeOfObjects() / MB); 2032 return heap_size_mb / kMbPerMs; 2033 } 2034 2035 // Returns true if no more GC work is left. 2036 bool IdleGlobalGC(); 2037 2038 void AdvanceIdleIncrementalMarking(intptr_t step_size); 2039 2040 void ClearObjectStats(bool clear_last_time_stats = false); 2041 set_weak_object_to_code_table(Object * value)2042 void set_weak_object_to_code_table(Object* value) { 2043 ASSERT(!InNewSpace(value)); 2044 weak_object_to_code_table_ = value; 2045 } 2046 weak_object_to_code_table_address()2047 Object** weak_object_to_code_table_address() { 2048 return &weak_object_to_code_table_; 2049 } 2050 2051 static const int kInitialStringTableSize = 2048; 2052 static const int kInitialEvalCacheSize = 64; 2053 static const int kInitialNumberStringCacheSize = 256; 2054 2055 // Object counts and used memory by InstanceType 2056 size_t object_counts_[OBJECT_STATS_COUNT]; 2057 size_t object_counts_last_time_[OBJECT_STATS_COUNT]; 2058 size_t object_sizes_[OBJECT_STATS_COUNT]; 2059 size_t object_sizes_last_time_[OBJECT_STATS_COUNT]; 2060 2061 // Maximum GC pause. 2062 double max_gc_pause_; 2063 2064 // Total time spent in GC. 2065 double total_gc_time_ms_; 2066 2067 // Maximum size of objects alive after GC. 2068 intptr_t max_alive_after_gc_; 2069 2070 // Minimal interval between two subsequent collections. 2071 double min_in_mutator_; 2072 2073 // Size of objects alive after last GC. 2074 intptr_t alive_after_last_gc_; 2075 2076 double last_gc_end_timestamp_; 2077 2078 // Cumulative GC time spent in marking 2079 double marking_time_; 2080 2081 // Cumulative GC time spent in sweeping 2082 double sweeping_time_; 2083 2084 MarkCompactCollector mark_compact_collector_; 2085 2086 StoreBuffer store_buffer_; 2087 2088 Marking marking_; 2089 2090 IncrementalMarking incremental_marking_; 2091 2092 int number_idle_notifications_; 2093 unsigned int last_idle_notification_gc_count_; 2094 bool last_idle_notification_gc_count_init_; 2095 2096 int mark_sweeps_since_idle_round_started_; 2097 unsigned int gc_count_at_last_idle_gc_; 2098 int scavenges_since_last_idle_round_; 2099 2100 // These two counters are monotomically increasing and never reset. 2101 size_t full_codegen_bytes_generated_; 2102 size_t crankshaft_codegen_bytes_generated_; 2103 2104 // If the --deopt_every_n_garbage_collections flag is set to a positive value, 2105 // this variable holds the number of garbage collections since the last 2106 // deoptimization triggered by garbage collection. 2107 int gcs_since_last_deopt_; 2108 2109 #ifdef VERIFY_HEAP 2110 int no_weak_object_verification_scope_depth_; 2111 #endif 2112 2113 static const int kAllocationSiteScratchpadSize = 256; 2114 int allocation_sites_scratchpad_length_; 2115 2116 static const int kMaxMarkSweepsInIdleRound = 7; 2117 static const int kIdleScavengeThreshold = 5; 2118 2119 // Shared state read by the scavenge collector and set by ScavengeObject. 2120 PromotionQueue promotion_queue_; 2121 2122 // Flag is set when the heap has been configured. The heap can be repeatedly 2123 // configured through the API until it is set up. 2124 bool configured_; 2125 2126 ExternalStringTable external_string_table_; 2127 2128 VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_; 2129 2130 MemoryChunk* chunks_queued_for_free_; 2131 2132 Mutex relocation_mutex_; 2133 2134 int gc_callbacks_depth_; 2135 2136 friend class AlwaysAllocateScope; 2137 friend class Factory; 2138 friend class GCCallbacksScope; 2139 friend class GCTracer; 2140 friend class HeapIterator; 2141 friend class Isolate; 2142 friend class MarkCompactCollector; 2143 friend class MarkCompactMarkingVisitor; 2144 friend class MapCompact; 2145 #ifdef VERIFY_HEAP 2146 friend class NoWeakObjectVerificationScope; 2147 #endif 2148 friend class Page; 2149 2150 DISALLOW_COPY_AND_ASSIGN(Heap); 2151 }; 2152 2153 2154 class HeapStats { 2155 public: 2156 static const int kStartMarker = 0xDECADE00; 2157 static const int kEndMarker = 0xDECADE01; 2158 2159 int* start_marker; // 0 2160 int* new_space_size; // 1 2161 int* new_space_capacity; // 2 2162 intptr_t* old_pointer_space_size; // 3 2163 intptr_t* old_pointer_space_capacity; // 4 2164 intptr_t* old_data_space_size; // 5 2165 intptr_t* old_data_space_capacity; // 6 2166 intptr_t* code_space_size; // 7 2167 intptr_t* code_space_capacity; // 8 2168 intptr_t* map_space_size; // 9 2169 intptr_t* map_space_capacity; // 10 2170 intptr_t* cell_space_size; // 11 2171 intptr_t* cell_space_capacity; // 12 2172 intptr_t* lo_space_size; // 13 2173 int* global_handle_count; // 14 2174 int* weak_global_handle_count; // 15 2175 int* pending_global_handle_count; // 16 2176 int* near_death_global_handle_count; // 17 2177 int* free_global_handle_count; // 18 2178 intptr_t* memory_allocator_size; // 19 2179 intptr_t* memory_allocator_capacity; // 20 2180 int* objects_per_type; // 21 2181 int* size_per_type; // 22 2182 int* os_error; // 23 2183 int* end_marker; // 24 2184 intptr_t* property_cell_space_size; // 25 2185 intptr_t* property_cell_space_capacity; // 26 2186 }; 2187 2188 2189 class AlwaysAllocateScope { 2190 public: 2191 explicit inline AlwaysAllocateScope(Isolate* isolate); 2192 inline ~AlwaysAllocateScope(); 2193 2194 private: 2195 // Implicitly disable artificial allocation failures. 2196 Heap* heap_; 2197 DisallowAllocationFailure daf_; 2198 }; 2199 2200 2201 #ifdef VERIFY_HEAP 2202 class NoWeakObjectVerificationScope { 2203 public: 2204 inline NoWeakObjectVerificationScope(); 2205 inline ~NoWeakObjectVerificationScope(); 2206 }; 2207 #endif 2208 2209 2210 class GCCallbacksScope { 2211 public: 2212 explicit inline GCCallbacksScope(Heap* heap); 2213 inline ~GCCallbacksScope(); 2214 2215 inline bool CheckReenter(); 2216 2217 private: 2218 Heap* heap_; 2219 }; 2220 2221 2222 // Visitor class to verify interior pointers in spaces that do not contain 2223 // or care about intergenerational references. All heap object pointers have to 2224 // point into the heap to a location that has a map pointer at its first word. 2225 // Caveat: Heap::Contains is an approximation because it can return true for 2226 // objects in a heap space but above the allocation pointer. 2227 class VerifyPointersVisitor: public ObjectVisitor { 2228 public: 2229 inline void VisitPointers(Object** start, Object** end); 2230 }; 2231 2232 2233 // Verify that all objects are Smis. 2234 class VerifySmisVisitor: public ObjectVisitor { 2235 public: 2236 inline void VisitPointers(Object** start, Object** end); 2237 }; 2238 2239 2240 // Space iterator for iterating over all spaces of the heap. Returns each space 2241 // in turn, and null when it is done. 2242 class AllSpaces BASE_EMBEDDED { 2243 public: AllSpaces(Heap * heap)2244 explicit AllSpaces(Heap* heap) : heap_(heap), counter_(FIRST_SPACE) {} 2245 Space* next(); 2246 private: 2247 Heap* heap_; 2248 int counter_; 2249 }; 2250 2251 2252 // Space iterator for iterating over all old spaces of the heap: Old pointer 2253 // space, old data space and code space. Returns each space in turn, and null 2254 // when it is done. 2255 class OldSpaces BASE_EMBEDDED { 2256 public: OldSpaces(Heap * heap)2257 explicit OldSpaces(Heap* heap) : heap_(heap), counter_(OLD_POINTER_SPACE) {} 2258 OldSpace* next(); 2259 private: 2260 Heap* heap_; 2261 int counter_; 2262 }; 2263 2264 2265 // Space iterator for iterating over all the paged spaces of the heap: Map 2266 // space, old pointer space, old data space, code space and cell space. Returns 2267 // each space in turn, and null when it is done. 2268 class PagedSpaces BASE_EMBEDDED { 2269 public: PagedSpaces(Heap * heap)2270 explicit PagedSpaces(Heap* heap) : heap_(heap), counter_(OLD_POINTER_SPACE) {} 2271 PagedSpace* next(); 2272 private: 2273 Heap* heap_; 2274 int counter_; 2275 }; 2276 2277 2278 // Space iterator for iterating over all spaces of the heap. 2279 // For each space an object iterator is provided. The deallocation of the 2280 // returned object iterators is handled by the space iterator. 2281 class SpaceIterator : public Malloced { 2282 public: 2283 explicit SpaceIterator(Heap* heap); 2284 SpaceIterator(Heap* heap, HeapObjectCallback size_func); 2285 virtual ~SpaceIterator(); 2286 2287 bool has_next(); 2288 ObjectIterator* next(); 2289 2290 private: 2291 ObjectIterator* CreateIterator(); 2292 2293 Heap* heap_; 2294 int current_space_; // from enum AllocationSpace. 2295 ObjectIterator* iterator_; // object iterator for the current space. 2296 HeapObjectCallback size_func_; 2297 }; 2298 2299 2300 // A HeapIterator provides iteration over the whole heap. It 2301 // aggregates the specific iterators for the different spaces as 2302 // these can only iterate over one space only. 2303 // 2304 // HeapIterator ensures there is no allocation during its lifetime 2305 // (using an embedded DisallowHeapAllocation instance). 2306 // 2307 // HeapIterator can skip free list nodes (that is, de-allocated heap 2308 // objects that still remain in the heap). As implementation of free 2309 // nodes filtering uses GC marks, it can't be used during MS/MC GC 2310 // phases. Also, it is forbidden to interrupt iteration in this mode, 2311 // as this will leave heap objects marked (and thus, unusable). 2312 class HeapObjectsFilter; 2313 2314 class HeapIterator BASE_EMBEDDED { 2315 public: 2316 enum HeapObjectsFiltering { 2317 kNoFiltering, 2318 kFilterUnreachable 2319 }; 2320 2321 explicit HeapIterator(Heap* heap); 2322 HeapIterator(Heap* heap, HeapObjectsFiltering filtering); 2323 ~HeapIterator(); 2324 2325 HeapObject* next(); 2326 void reset(); 2327 2328 private: 2329 struct MakeHeapIterableHelper { MakeHeapIterableHelperMakeHeapIterableHelper2330 explicit MakeHeapIterableHelper(Heap* heap) { heap->MakeHeapIterable(); } 2331 }; 2332 2333 // Perform the initialization. 2334 void Init(); 2335 // Perform all necessary shutdown (destruction) work. 2336 void Shutdown(); 2337 HeapObject* NextObject(); 2338 2339 MakeHeapIterableHelper make_heap_iterable_helper_; 2340 DisallowHeapAllocation no_heap_allocation_; 2341 Heap* heap_; 2342 HeapObjectsFiltering filtering_; 2343 HeapObjectsFilter* filter_; 2344 // Space iterator for iterating all the spaces. 2345 SpaceIterator* space_iterator_; 2346 // Object iterator for the space currently being iterated. 2347 ObjectIterator* object_iterator_; 2348 }; 2349 2350 2351 // Cache for mapping (map, property name) into field offset. 2352 // Cleared at startup and prior to mark sweep collection. 2353 class KeyedLookupCache { 2354 public: 2355 // Lookup field offset for (map, name). If absent, -1 is returned. 2356 int Lookup(Handle<Map> map, Handle<Name> name); 2357 2358 // Update an element in the cache. 2359 void Update(Handle<Map> map, Handle<Name> name, int field_offset); 2360 2361 // Clear the cache. 2362 void Clear(); 2363 2364 static const int kLength = 256; 2365 static const int kCapacityMask = kLength - 1; 2366 static const int kMapHashShift = 5; 2367 static const int kHashMask = -4; // Zero the last two bits. 2368 static const int kEntriesPerBucket = 4; 2369 static const int kEntryLength = 2; 2370 static const int kMapIndex = 0; 2371 static const int kKeyIndex = 1; 2372 static const int kNotFound = -1; 2373 2374 // kEntriesPerBucket should be a power of 2. 2375 STATIC_ASSERT((kEntriesPerBucket & (kEntriesPerBucket - 1)) == 0); 2376 STATIC_ASSERT(kEntriesPerBucket == -kHashMask); 2377 2378 private: KeyedLookupCache()2379 KeyedLookupCache() { 2380 for (int i = 0; i < kLength; ++i) { 2381 keys_[i].map = NULL; 2382 keys_[i].name = NULL; 2383 field_offsets_[i] = kNotFound; 2384 } 2385 } 2386 2387 static inline int Hash(Handle<Map> map, Handle<Name> name); 2388 2389 // Get the address of the keys and field_offsets arrays. Used in 2390 // generated code to perform cache lookups. keys_address()2391 Address keys_address() { 2392 return reinterpret_cast<Address>(&keys_); 2393 } 2394 field_offsets_address()2395 Address field_offsets_address() { 2396 return reinterpret_cast<Address>(&field_offsets_); 2397 } 2398 2399 struct Key { 2400 Map* map; 2401 Name* name; 2402 }; 2403 2404 Key keys_[kLength]; 2405 int field_offsets_[kLength]; 2406 2407 friend class ExternalReference; 2408 friend class Isolate; 2409 DISALLOW_COPY_AND_ASSIGN(KeyedLookupCache); 2410 }; 2411 2412 2413 // Cache for mapping (map, property name) into descriptor index. 2414 // The cache contains both positive and negative results. 2415 // Descriptor index equals kNotFound means the property is absent. 2416 // Cleared at startup and prior to any gc. 2417 class DescriptorLookupCache { 2418 public: 2419 // Lookup descriptor index for (map, name). 2420 // If absent, kAbsent is returned. Lookup(Map * source,Name * name)2421 int Lookup(Map* source, Name* name) { 2422 if (!name->IsUniqueName()) return kAbsent; 2423 int index = Hash(source, name); 2424 Key& key = keys_[index]; 2425 if ((key.source == source) && (key.name == name)) return results_[index]; 2426 return kAbsent; 2427 } 2428 2429 // Update an element in the cache. Update(Map * source,Name * name,int result)2430 void Update(Map* source, Name* name, int result) { 2431 ASSERT(result != kAbsent); 2432 if (name->IsUniqueName()) { 2433 int index = Hash(source, name); 2434 Key& key = keys_[index]; 2435 key.source = source; 2436 key.name = name; 2437 results_[index] = result; 2438 } 2439 } 2440 2441 // Clear the cache. 2442 void Clear(); 2443 2444 static const int kAbsent = -2; 2445 2446 private: DescriptorLookupCache()2447 DescriptorLookupCache() { 2448 for (int i = 0; i < kLength; ++i) { 2449 keys_[i].source = NULL; 2450 keys_[i].name = NULL; 2451 results_[i] = kAbsent; 2452 } 2453 } 2454 Hash(Object * source,Name * name)2455 static int Hash(Object* source, Name* name) { 2456 // Uses only lower 32 bits if pointers are larger. 2457 uint32_t source_hash = 2458 static_cast<uint32_t>(reinterpret_cast<uintptr_t>(source)) 2459 >> kPointerSizeLog2; 2460 uint32_t name_hash = 2461 static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name)) 2462 >> kPointerSizeLog2; 2463 return (source_hash ^ name_hash) % kLength; 2464 } 2465 2466 static const int kLength = 64; 2467 struct Key { 2468 Map* source; 2469 Name* name; 2470 }; 2471 2472 Key keys_[kLength]; 2473 int results_[kLength]; 2474 2475 friend class Isolate; 2476 DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache); 2477 }; 2478 2479 2480 // GCTracer collects and prints ONE line after each garbage collector 2481 // invocation IFF --trace_gc is used. 2482 2483 class GCTracer BASE_EMBEDDED { 2484 public: 2485 class Scope BASE_EMBEDDED { 2486 public: 2487 enum ScopeId { 2488 EXTERNAL, 2489 MC_MARK, 2490 MC_SWEEP, 2491 MC_SWEEP_NEWSPACE, 2492 MC_SWEEP_OLDSPACE, 2493 MC_EVACUATE_PAGES, 2494 MC_UPDATE_NEW_TO_NEW_POINTERS, 2495 MC_UPDATE_ROOT_TO_NEW_POINTERS, 2496 MC_UPDATE_OLD_TO_NEW_POINTERS, 2497 MC_UPDATE_POINTERS_TO_EVACUATED, 2498 MC_UPDATE_POINTERS_BETWEEN_EVACUATED, 2499 MC_UPDATE_MISC_POINTERS, 2500 MC_WEAKCOLLECTION_PROCESS, 2501 MC_WEAKCOLLECTION_CLEAR, 2502 MC_FLUSH_CODE, 2503 kNumberOfScopes 2504 }; 2505 Scope(GCTracer * tracer,ScopeId scope)2506 Scope(GCTracer* tracer, ScopeId scope) 2507 : tracer_(tracer), 2508 scope_(scope) { 2509 start_time_ = OS::TimeCurrentMillis(); 2510 } 2511 ~Scope()2512 ~Scope() { 2513 ASSERT(scope_ < kNumberOfScopes); // scope_ is unsigned. 2514 tracer_->scopes_[scope_] += OS::TimeCurrentMillis() - start_time_; 2515 } 2516 2517 private: 2518 GCTracer* tracer_; 2519 ScopeId scope_; 2520 double start_time_; 2521 }; 2522 2523 explicit GCTracer(Heap* heap, 2524 const char* gc_reason, 2525 const char* collector_reason); 2526 ~GCTracer(); 2527 2528 // Sets the collector. set_collector(GarbageCollector collector)2529 void set_collector(GarbageCollector collector) { collector_ = collector; } 2530 2531 // Sets the GC count. set_gc_count(unsigned int count)2532 void set_gc_count(unsigned int count) { gc_count_ = count; } 2533 2534 // Sets the full GC count. set_full_gc_count(int count)2535 void set_full_gc_count(int count) { full_gc_count_ = count; } 2536 increment_nodes_died_in_new_space()2537 void increment_nodes_died_in_new_space() { 2538 nodes_died_in_new_space_++; 2539 } 2540 increment_nodes_copied_in_new_space()2541 void increment_nodes_copied_in_new_space() { 2542 nodes_copied_in_new_space_++; 2543 } 2544 increment_nodes_promoted()2545 void increment_nodes_promoted() { 2546 nodes_promoted_++; 2547 } 2548 2549 private: 2550 // Returns a string matching the collector. 2551 const char* CollectorString(); 2552 2553 // Returns size of object in heap (in MB). 2554 inline double SizeOfHeapObjects(); 2555 2556 // Timestamp set in the constructor. 2557 double start_time_; 2558 2559 // Size of objects in heap set in constructor. 2560 intptr_t start_object_size_; 2561 2562 // Size of memory allocated from OS set in constructor. 2563 intptr_t start_memory_size_; 2564 2565 // Type of collector. 2566 GarbageCollector collector_; 2567 2568 // A count (including this one, e.g. the first collection is 1) of the 2569 // number of garbage collections. 2570 unsigned int gc_count_; 2571 2572 // A count (including this one) of the number of full garbage collections. 2573 int full_gc_count_; 2574 2575 // Amounts of time spent in different scopes during GC. 2576 double scopes_[Scope::kNumberOfScopes]; 2577 2578 // Total amount of space either wasted or contained in one of free lists 2579 // before the current GC. 2580 intptr_t in_free_list_or_wasted_before_gc_; 2581 2582 // Difference between space used in the heap at the beginning of the current 2583 // collection and the end of the previous collection. 2584 intptr_t allocated_since_last_gc_; 2585 2586 // Amount of time spent in mutator that is time elapsed between end of the 2587 // previous collection and the beginning of the current one. 2588 double spent_in_mutator_; 2589 2590 // Number of died nodes in the new space. 2591 int nodes_died_in_new_space_; 2592 2593 // Number of copied nodes to the new space. 2594 int nodes_copied_in_new_space_; 2595 2596 // Number of promoted nodes to the old space. 2597 int nodes_promoted_; 2598 2599 // Incremental marking steps counters. 2600 int steps_count_; 2601 double steps_took_; 2602 double longest_step_; 2603 int steps_count_since_last_gc_; 2604 double steps_took_since_last_gc_; 2605 2606 Heap* heap_; 2607 2608 const char* gc_reason_; 2609 const char* collector_reason_; 2610 }; 2611 2612 2613 class RegExpResultsCache { 2614 public: 2615 enum ResultsCacheType { REGEXP_MULTIPLE_INDICES, STRING_SPLIT_SUBSTRINGS }; 2616 2617 // Attempt to retrieve a cached result. On failure, 0 is returned as a Smi. 2618 // On success, the returned result is guaranteed to be a COW-array. 2619 static Object* Lookup(Heap* heap, 2620 String* key_string, 2621 Object* key_pattern, 2622 ResultsCacheType type); 2623 // Attempt to add value_array to the cache specified by type. On success, 2624 // value_array is turned into a COW-array. 2625 static void Enter(Isolate* isolate, 2626 Handle<String> key_string, 2627 Handle<Object> key_pattern, 2628 Handle<FixedArray> value_array, 2629 ResultsCacheType type); 2630 static void Clear(FixedArray* cache); 2631 static const int kRegExpResultsCacheSize = 0x100; 2632 2633 private: 2634 static const int kArrayEntriesPerCacheEntry = 4; 2635 static const int kStringOffset = 0; 2636 static const int kPatternOffset = 1; 2637 static const int kArrayOffset = 2; 2638 }; 2639 2640 2641 // Abstract base class for checking whether a weak object should be retained. 2642 class WeakObjectRetainer { 2643 public: ~WeakObjectRetainer()2644 virtual ~WeakObjectRetainer() {} 2645 2646 // Return whether this object should be retained. If NULL is returned the 2647 // object has no references. Otherwise the address of the retained object 2648 // should be returned as in some GC situations the object has been moved. 2649 virtual Object* RetainAs(Object* object) = 0; 2650 }; 2651 2652 2653 // Intrusive object marking uses least significant bit of 2654 // heap object's map word to mark objects. 2655 // Normally all map words have least significant bit set 2656 // because they contain tagged map pointer. 2657 // If the bit is not set object is marked. 2658 // All objects should be unmarked before resuming 2659 // JavaScript execution. 2660 class IntrusiveMarking { 2661 public: IsMarked(HeapObject * object)2662 static bool IsMarked(HeapObject* object) { 2663 return (object->map_word().ToRawValue() & kNotMarkedBit) == 0; 2664 } 2665 ClearMark(HeapObject * object)2666 static void ClearMark(HeapObject* object) { 2667 uintptr_t map_word = object->map_word().ToRawValue(); 2668 object->set_map_word(MapWord::FromRawValue(map_word | kNotMarkedBit)); 2669 ASSERT(!IsMarked(object)); 2670 } 2671 SetMark(HeapObject * object)2672 static void SetMark(HeapObject* object) { 2673 uintptr_t map_word = object->map_word().ToRawValue(); 2674 object->set_map_word(MapWord::FromRawValue(map_word & ~kNotMarkedBit)); 2675 ASSERT(IsMarked(object)); 2676 } 2677 MapOfMarkedObject(HeapObject * object)2678 static Map* MapOfMarkedObject(HeapObject* object) { 2679 uintptr_t map_word = object->map_word().ToRawValue(); 2680 return MapWord::FromRawValue(map_word | kNotMarkedBit).ToMap(); 2681 } 2682 SizeOfMarkedObject(HeapObject * object)2683 static int SizeOfMarkedObject(HeapObject* object) { 2684 return object->SizeFromMap(MapOfMarkedObject(object)); 2685 } 2686 2687 private: 2688 static const uintptr_t kNotMarkedBit = 0x1; 2689 STATIC_ASSERT((kHeapObjectTag & kNotMarkedBit) != 0); // NOLINT 2690 }; 2691 2692 2693 #ifdef DEBUG 2694 // Helper class for tracing paths to a search target Object from all roots. 2695 // The TracePathFrom() method can be used to trace paths from a specific 2696 // object to the search target object. 2697 class PathTracer : public ObjectVisitor { 2698 public: 2699 enum WhatToFind { 2700 FIND_ALL, // Will find all matches. 2701 FIND_FIRST // Will stop the search after first match. 2702 }; 2703 2704 // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject. 2705 static const int kMarkTag = 2; 2706 2707 // For the WhatToFind arg, if FIND_FIRST is specified, tracing will stop 2708 // after the first match. If FIND_ALL is specified, then tracing will be 2709 // done for all matches. PathTracer(Object * search_target,WhatToFind what_to_find,VisitMode visit_mode)2710 PathTracer(Object* search_target, 2711 WhatToFind what_to_find, 2712 VisitMode visit_mode) 2713 : search_target_(search_target), 2714 found_target_(false), 2715 found_target_in_trace_(false), 2716 what_to_find_(what_to_find), 2717 visit_mode_(visit_mode), 2718 object_stack_(20), 2719 no_allocation() {} 2720 2721 virtual void VisitPointers(Object** start, Object** end); 2722 2723 void Reset(); 2724 void TracePathFrom(Object** root); 2725 found()2726 bool found() const { return found_target_; } 2727 2728 static Object* const kAnyGlobalObject; 2729 2730 protected: 2731 class MarkVisitor; 2732 class UnmarkVisitor; 2733 2734 void MarkRecursively(Object** p, MarkVisitor* mark_visitor); 2735 void UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor); 2736 virtual void ProcessResults(); 2737 2738 Object* search_target_; 2739 bool found_target_; 2740 bool found_target_in_trace_; 2741 WhatToFind what_to_find_; 2742 VisitMode visit_mode_; 2743 List<Object*> object_stack_; 2744 2745 DisallowHeapAllocation no_allocation; // i.e. no gc allowed. 2746 2747 private: 2748 DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer); 2749 }; 2750 #endif // DEBUG 2751 2752 } } // namespace v8::internal 2753 2754 #endif // V8_HEAP_H_ 2755