| OLD | NEW |
|---|
| (Empty) |
| 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_MARK_COMPACT_H_ | |
| 6 #define V8_MARK_COMPACT_H_ | |
| 7 | |
| 8 #include "src/compiler-intrinsics.h" | |
| 9 #include "src/spaces.h" | |
| 10 | |
| 11 namespace v8 { | |
| 12 namespace internal { | |
| 13 | |
| 14 // Callback function, returns whether an object is alive. The heap size | |
| 15 // of the object is returned in size. It optionally updates the offset | |
| 16 // to the first live object in the page (only used for old and map objects). | |
| 17 typedef bool (*IsAliveFunction)(HeapObject* obj, int* size, int* offset); | |
| 18 | |
| 19 // Forward declarations. | |
| 20 class CodeFlusher; | |
| 21 class MarkCompactCollector; | |
| 22 class MarkingVisitor; | |
| 23 class RootMarkingVisitor; | |
| 24 | |
| 25 | |
| 26 class Marking { | |
| 27 public: | |
| 28 explicit Marking(Heap* heap) | |
| 29 : heap_(heap) { | |
| 30 } | |
| 31 | |
| 32 INLINE(static MarkBit MarkBitFrom(Address addr)); | |
| 33 | |
| 34 INLINE(static MarkBit MarkBitFrom(HeapObject* obj)) { | |
| 35 return MarkBitFrom(reinterpret_cast<Address>(obj)); | |
| 36 } | |
| 37 | |
| 38 // Impossible markbits: 01 | |
| 39 static const char* kImpossibleBitPattern; | |
| 40 INLINE(static bool IsImpossible(MarkBit mark_bit)) { | |
| 41 return !mark_bit.Get() && mark_bit.Next().Get(); | |
| 42 } | |
| 43 | |
| 44 // Black markbits: 10 - this is required by the sweeper. | |
| 45 static const char* kBlackBitPattern; | |
| 46 INLINE(static bool IsBlack(MarkBit mark_bit)) { | |
| 47 return mark_bit.Get() && !mark_bit.Next().Get(); | |
| 48 } | |
| 49 | |
| 50 // White markbits: 00 - this is required by the mark bit clearer. | |
| 51 static const char* kWhiteBitPattern; | |
| 52 INLINE(static bool IsWhite(MarkBit mark_bit)) { | |
| 53 return !mark_bit.Get(); | |
| 54 } | |
| 55 | |
| 56 // Grey markbits: 11 | |
| 57 static const char* kGreyBitPattern; | |
| 58 INLINE(static bool IsGrey(MarkBit mark_bit)) { | |
| 59 return mark_bit.Get() && mark_bit.Next().Get(); | |
| 60 } | |
| 61 | |
| 62 INLINE(static void MarkBlack(MarkBit mark_bit)) { | |
| 63 mark_bit.Set(); | |
| 64 mark_bit.Next().Clear(); | |
| 65 } | |
| 66 | |
| 67 INLINE(static void BlackToGrey(MarkBit markbit)) { | |
| 68 markbit.Next().Set(); | |
| 69 } | |
| 70 | |
| 71 INLINE(static void WhiteToGrey(MarkBit markbit)) { | |
| 72 markbit.Set(); | |
| 73 markbit.Next().Set(); | |
| 74 } | |
| 75 | |
| 76 INLINE(static void GreyToBlack(MarkBit markbit)) { | |
| 77 markbit.Next().Clear(); | |
| 78 } | |
| 79 | |
| 80 INLINE(static void BlackToGrey(HeapObject* obj)) { | |
| 81 BlackToGrey(MarkBitFrom(obj)); | |
| 82 } | |
| 83 | |
| 84 INLINE(static void AnyToGrey(MarkBit markbit)) { | |
| 85 markbit.Set(); | |
| 86 markbit.Next().Set(); | |
| 87 } | |
| 88 | |
| 89 void TransferMark(Address old_start, Address new_start); | |
| 90 | |
| 91 #ifdef DEBUG | |
| 92 enum ObjectColor { | |
| 93 BLACK_OBJECT, | |
| 94 WHITE_OBJECT, | |
| 95 GREY_OBJECT, | |
| 96 IMPOSSIBLE_COLOR | |
| 97 }; | |
| 98 | |
| 99 static const char* ColorName(ObjectColor color) { | |
| 100 switch (color) { | |
| 101 case BLACK_OBJECT: return "black"; | |
| 102 case WHITE_OBJECT: return "white"; | |
| 103 case GREY_OBJECT: return "grey"; | |
| 104 case IMPOSSIBLE_COLOR: return "impossible"; | |
| 105 } | |
| 106 return "error"; | |
| 107 } | |
| 108 | |
| 109 static ObjectColor Color(HeapObject* obj) { | |
| 110 return Color(Marking::MarkBitFrom(obj)); | |
| 111 } | |
| 112 | |
| 113 static ObjectColor Color(MarkBit mark_bit) { | |
| 114 if (IsBlack(mark_bit)) return BLACK_OBJECT; | |
| 115 if (IsWhite(mark_bit)) return WHITE_OBJECT; | |
| 116 if (IsGrey(mark_bit)) return GREY_OBJECT; | |
| 117 UNREACHABLE(); | |
| 118 return IMPOSSIBLE_COLOR; | |
| 119 } | |
| 120 #endif | |
| 121 | |
| 122 // Returns true if the transferred color is black. | |
| 123 INLINE(static bool TransferColor(HeapObject* from, | |
| 124 HeapObject* to)) { | |
| 125 MarkBit from_mark_bit = MarkBitFrom(from); | |
| 126 MarkBit to_mark_bit = MarkBitFrom(to); | |
| 127 bool is_black = false; | |
| 128 if (from_mark_bit.Get()) { | |
| 129 to_mark_bit.Set(); | |
| 130 is_black = true; // Looks black so far. | |
| 131 } | |
| 132 if (from_mark_bit.Next().Get()) { | |
| 133 to_mark_bit.Next().Set(); | |
| 134 is_black = false; // Was actually gray. | |
| 135 } | |
| 136 return is_black; | |
| 137 } | |
| 138 | |
| 139 private: | |
| 140 Heap* heap_; | |
| 141 }; | |
| 142 | |
| 143 // ---------------------------------------------------------------------------- | |
| 144 // Marking deque for tracing live objects. | |
| 145 class MarkingDeque { | |
| 146 public: | |
| 147 MarkingDeque() | |
| 148 : array_(NULL), top_(0), bottom_(0), mask_(0), overflowed_(false) { } | |
| 149 | |
| 150 void Initialize(Address low, Address high) { | |
| 151 HeapObject** obj_low = reinterpret_cast<HeapObject**>(low); | |
| 152 HeapObject** obj_high = reinterpret_cast<HeapObject**>(high); | |
| 153 array_ = obj_low; | |
| 154 mask_ = RoundDownToPowerOf2(static_cast<int>(obj_high - obj_low)) - 1; | |
| 155 top_ = bottom_ = 0; | |
| 156 overflowed_ = false; | |
| 157 } | |
| 158 | |
| 159 inline bool IsFull() { return ((top_ + 1) & mask_) == bottom_; } | |
| 160 | |
| 161 inline bool IsEmpty() { return top_ == bottom_; } | |
| 162 | |
| 163 bool overflowed() const { return overflowed_; } | |
| 164 | |
| 165 void ClearOverflowed() { overflowed_ = false; } | |
| 166 | |
| 167 void SetOverflowed() { overflowed_ = true; } | |
| 168 | |
| 169 // Push the (marked) object on the marking stack if there is room, | |
| 170 // otherwise mark the object as overflowed and wait for a rescan of the | |
| 171 // heap. | |
| 172 INLINE(void PushBlack(HeapObject* object)) { | |
| 173 DCHECK(object->IsHeapObject()); | |
| 174 if (IsFull()) { | |
| 175 Marking::BlackToGrey(object); | |
| 176 MemoryChunk::IncrementLiveBytesFromGC(object->address(), -object->Size()); | |
| 177 SetOverflowed(); | |
| 178 } else { | |
| 179 array_[top_] = object; | |
| 180 top_ = ((top_ + 1) & mask_); | |
| 181 } | |
| 182 } | |
| 183 | |
| 184 INLINE(void PushGrey(HeapObject* object)) { | |
| 185 DCHECK(object->IsHeapObject()); | |
| 186 if (IsFull()) { | |
| 187 SetOverflowed(); | |
| 188 } else { | |
| 189 array_[top_] = object; | |
| 190 top_ = ((top_ + 1) & mask_); | |
| 191 } | |
| 192 } | |
| 193 | |
| 194 INLINE(HeapObject* Pop()) { | |
| 195 DCHECK(!IsEmpty()); | |
| 196 top_ = ((top_ - 1) & mask_); | |
| 197 HeapObject* object = array_[top_]; | |
| 198 DCHECK(object->IsHeapObject()); | |
| 199 return object; | |
| 200 } | |
| 201 | |
| 202 INLINE(void UnshiftGrey(HeapObject* object)) { | |
| 203 DCHECK(object->IsHeapObject()); | |
| 204 if (IsFull()) { | |
| 205 SetOverflowed(); | |
| 206 } else { | |
| 207 bottom_ = ((bottom_ - 1) & mask_); | |
| 208 array_[bottom_] = object; | |
| 209 } | |
| 210 } | |
| 211 | |
| 212 HeapObject** array() { return array_; } | |
| 213 int bottom() { return bottom_; } | |
| 214 int top() { return top_; } | |
| 215 int mask() { return mask_; } | |
| 216 void set_top(int top) { top_ = top; } | |
| 217 | |
| 218 private: | |
| 219 HeapObject** array_; | |
| 220 // array_[(top - 1) & mask_] is the top element in the deque. The Deque is | |
| 221 // empty when top_ == bottom_. It is full when top_ + 1 == bottom | |
| 222 // (mod mask + 1). | |
| 223 int top_; | |
| 224 int bottom_; | |
| 225 int mask_; | |
| 226 bool overflowed_; | |
| 227 | |
| 228 DISALLOW_COPY_AND_ASSIGN(MarkingDeque); | |
| 229 }; | |
| 230 | |
| 231 | |
| 232 class SlotsBufferAllocator { | |
| 233 public: | |
| 234 SlotsBuffer* AllocateBuffer(SlotsBuffer* next_buffer); | |
| 235 void DeallocateBuffer(SlotsBuffer* buffer); | |
| 236 | |
| 237 void DeallocateChain(SlotsBuffer** buffer_address); | |
| 238 }; | |
| 239 | |
| 240 | |
| 241 // SlotsBuffer records a sequence of slots that has to be updated | |
| 242 // after live objects were relocated from evacuation candidates. | |
| 243 // All slots are either untyped or typed: | |
| 244 // - Untyped slots are expected to contain a tagged object pointer. | |
| 245 // They are recorded by an address. | |
| 246 // - Typed slots are expected to contain an encoded pointer to a heap | |
| 247 // object where the way of encoding depends on the type of the slot. | |
| 248 // They are recorded as a pair (SlotType, slot address). | |
| 249 // We assume that zero-page is never mapped this allows us to distinguish | |
| 250 // untyped slots from typed slots during iteration by a simple comparison: | |
| 251 // if element of slots buffer is less than NUMBER_OF_SLOT_TYPES then it | |
| 252 // is the first element of typed slot's pair. | |
| 253 class SlotsBuffer { | |
| 254 public: | |
| 255 typedef Object** ObjectSlot; | |
| 256 | |
| 257 explicit SlotsBuffer(SlotsBuffer* next_buffer) | |
| 258 : idx_(0), chain_length_(1), next_(next_buffer) { | |
| 259 if (next_ != NULL) { | |
| 260 chain_length_ = next_->chain_length_ + 1; | |
| 261 } | |
| 262 } | |
| 263 | |
| 264 ~SlotsBuffer() { | |
| 265 } | |
| 266 | |
| 267 void Add(ObjectSlot slot) { | |
| 268 DCHECK(0 <= idx_ && idx_ < kNumberOfElements); | |
| 269 slots_[idx_++] = slot; | |
| 270 } | |
| 271 | |
| 272 enum SlotType { | |
| 273 EMBEDDED_OBJECT_SLOT, | |
| 274 RELOCATED_CODE_OBJECT, | |
| 275 CODE_TARGET_SLOT, | |
| 276 CODE_ENTRY_SLOT, | |
| 277 DEBUG_TARGET_SLOT, | |
| 278 JS_RETURN_SLOT, | |
| 279 NUMBER_OF_SLOT_TYPES | |
| 280 }; | |
| 281 | |
| 282 static const char* SlotTypeToString(SlotType type) { | |
| 283 switch (type) { | |
| 284 case EMBEDDED_OBJECT_SLOT: | |
| 285 return "EMBEDDED_OBJECT_SLOT"; | |
| 286 case RELOCATED_CODE_OBJECT: | |
| 287 return "RELOCATED_CODE_OBJECT"; | |
| 288 case CODE_TARGET_SLOT: | |
| 289 return "CODE_TARGET_SLOT"; | |
| 290 case CODE_ENTRY_SLOT: | |
| 291 return "CODE_ENTRY_SLOT"; | |
| 292 case DEBUG_TARGET_SLOT: | |
| 293 return "DEBUG_TARGET_SLOT"; | |
| 294 case JS_RETURN_SLOT: | |
| 295 return "JS_RETURN_SLOT"; | |
| 296 case NUMBER_OF_SLOT_TYPES: | |
| 297 return "NUMBER_OF_SLOT_TYPES"; | |
| 298 } | |
| 299 return "UNKNOWN SlotType"; | |
| 300 } | |
| 301 | |
| 302 void UpdateSlots(Heap* heap); | |
| 303 | |
| 304 void UpdateSlotsWithFilter(Heap* heap); | |
| 305 | |
| 306 SlotsBuffer* next() { return next_; } | |
| 307 | |
| 308 static int SizeOfChain(SlotsBuffer* buffer) { | |
| 309 if (buffer == NULL) return 0; | |
| 310 return static_cast<int>(buffer->idx_ + | |
| 311 (buffer->chain_length_ - 1) * kNumberOfElements); | |
| 312 } | |
| 313 | |
| 314 inline bool IsFull() { | |
| 315 return idx_ == kNumberOfElements; | |
| 316 } | |
| 317 | |
| 318 inline bool HasSpaceForTypedSlot() { | |
| 319 return idx_ < kNumberOfElements - 1; | |
| 320 } | |
| 321 | |
| 322 static void UpdateSlotsRecordedIn(Heap* heap, | |
| 323 SlotsBuffer* buffer, | |
| 324 bool code_slots_filtering_required) { | |
| 325 while (buffer != NULL) { | |
| 326 if (code_slots_filtering_required) { | |
| 327 buffer->UpdateSlotsWithFilter(heap); | |
| 328 } else { | |
| 329 buffer->UpdateSlots(heap); | |
| 330 } | |
| 331 buffer = buffer->next(); | |
| 332 } | |
| 333 } | |
| 334 | |
| 335 enum AdditionMode { | |
| 336 FAIL_ON_OVERFLOW, | |
| 337 IGNORE_OVERFLOW | |
| 338 }; | |
| 339 | |
| 340 static bool ChainLengthThresholdReached(SlotsBuffer* buffer) { | |
| 341 return buffer != NULL && buffer->chain_length_ >= kChainLengthThreshold; | |
| 342 } | |
| 343 | |
| 344 INLINE(static bool AddTo(SlotsBufferAllocator* allocator, | |
| 345 SlotsBuffer** buffer_address, | |
| 346 ObjectSlot slot, | |
| 347 AdditionMode mode)) { | |
| 348 SlotsBuffer* buffer = *buffer_address; | |
| 349 if (buffer == NULL || buffer->IsFull()) { | |
| 350 if (mode == FAIL_ON_OVERFLOW && ChainLengthThresholdReached(buffer)) { | |
| 351 allocator->DeallocateChain(buffer_address); | |
| 352 return false; | |
| 353 } | |
| 354 buffer = allocator->AllocateBuffer(buffer); | |
| 355 *buffer_address = buffer; | |
| 356 } | |
| 357 buffer->Add(slot); | |
| 358 return true; | |
| 359 } | |
| 360 | |
| 361 static bool IsTypedSlot(ObjectSlot slot); | |
| 362 | |
| 363 static bool AddTo(SlotsBufferAllocator* allocator, | |
| 364 SlotsBuffer** buffer_address, | |
| 365 SlotType type, | |
| 366 Address addr, | |
| 367 AdditionMode mode); | |
| 368 | |
| 369 static const int kNumberOfElements = 1021; | |
| 370 | |
| 371 private: | |
| 372 static const int kChainLengthThreshold = 15; | |
| 373 | |
| 374 intptr_t idx_; | |
| 375 intptr_t chain_length_; | |
| 376 SlotsBuffer* next_; | |
| 377 ObjectSlot slots_[kNumberOfElements]; | |
| 378 }; | |
| 379 | |
| 380 | |
| 381 // CodeFlusher collects candidates for code flushing during marking and | |
| 382 // processes those candidates after marking has completed in order to | |
| 383 // reset those functions referencing code objects that would otherwise | |
| 384 // be unreachable. Code objects can be referenced in three ways: | |
| 385 // - SharedFunctionInfo references unoptimized code. | |
| 386 // - JSFunction references either unoptimized or optimized code. | |
| 387 // - OptimizedCodeMap references optimized code. | |
| 388 // We are not allowed to flush unoptimized code for functions that got | |
| 389 // optimized or inlined into optimized code, because we might bailout | |
| 390 // into the unoptimized code again during deoptimization. | |
| 391 class CodeFlusher { | |
| 392 public: | |
| 393 explicit CodeFlusher(Isolate* isolate) | |
| 394 : isolate_(isolate), | |
| 395 jsfunction_candidates_head_(NULL), | |
| 396 shared_function_info_candidates_head_(NULL), | |
| 397 optimized_code_map_holder_head_(NULL) {} | |
| 398 | |
| 399 void AddCandidate(SharedFunctionInfo* shared_info) { | |
| 400 if (GetNextCandidate(shared_info) == NULL) { | |
| 401 SetNextCandidate(shared_info, shared_function_info_candidates_head_); | |
| 402 shared_function_info_candidates_head_ = shared_info; | |
| 403 } | |
| 404 } | |
| 405 | |
| 406 void AddCandidate(JSFunction* function) { | |
| 407 DCHECK(function->code() == function->shared()->code()); | |
| 408 if (GetNextCandidate(function)->IsUndefined()) { | |
| 409 SetNextCandidate(function, jsfunction_candidates_head_); | |
| 410 jsfunction_candidates_head_ = function; | |
| 411 } | |
| 412 } | |
| 413 | |
| 414 void AddOptimizedCodeMap(SharedFunctionInfo* code_map_holder) { | |
| 415 if (GetNextCodeMap(code_map_holder)->IsUndefined()) { | |
| 416 SetNextCodeMap(code_map_holder, optimized_code_map_holder_head_); | |
| 417 optimized_code_map_holder_head_ = code_map_holder; | |
| 418 } | |
| 419 } | |
| 420 | |
| 421 void EvictOptimizedCodeMap(SharedFunctionInfo* code_map_holder); | |
| 422 void EvictCandidate(SharedFunctionInfo* shared_info); | |
| 423 void EvictCandidate(JSFunction* function); | |
| 424 | |
| 425 void ProcessCandidates() { | |
| 426 ProcessOptimizedCodeMaps(); | |
| 427 ProcessSharedFunctionInfoCandidates(); | |
| 428 ProcessJSFunctionCandidates(); | |
| 429 } | |
| 430 | |
| 431 void EvictAllCandidates() { | |
| 432 EvictOptimizedCodeMaps(); | |
| 433 EvictJSFunctionCandidates(); | |
| 434 EvictSharedFunctionInfoCandidates(); | |
| 435 } | |
| 436 | |
| 437 void IteratePointersToFromSpace(ObjectVisitor* v); | |
| 438 | |
| 439 private: | |
| 440 void ProcessOptimizedCodeMaps(); | |
| 441 void ProcessJSFunctionCandidates(); | |
| 442 void ProcessSharedFunctionInfoCandidates(); | |
| 443 void EvictOptimizedCodeMaps(); | |
| 444 void EvictJSFunctionCandidates(); | |
| 445 void EvictSharedFunctionInfoCandidates(); | |
| 446 | |
| 447 static JSFunction** GetNextCandidateSlot(JSFunction* candidate) { | |
| 448 return reinterpret_cast<JSFunction**>( | |
| 449 HeapObject::RawField(candidate, JSFunction::kNextFunctionLinkOffset)); | |
| 450 } | |
| 451 | |
| 452 static JSFunction* GetNextCandidate(JSFunction* candidate) { | |
| 453 Object* next_candidate = candidate->next_function_link(); | |
| 454 return reinterpret_cast<JSFunction*>(next_candidate); | |
| 455 } | |
| 456 | |
| 457 static void SetNextCandidate(JSFunction* candidate, | |
| 458 JSFunction* next_candidate) { | |
| 459 candidate->set_next_function_link(next_candidate); | |
| 460 } | |
| 461 | |
| 462 static void ClearNextCandidate(JSFunction* candidate, Object* undefined) { | |
| 463 DCHECK(undefined->IsUndefined()); | |
| 464 candidate->set_next_function_link(undefined, SKIP_WRITE_BARRIER); | |
| 465 } | |
| 466 | |
| 467 static SharedFunctionInfo* GetNextCandidate(SharedFunctionInfo* candidate) { | |
| 468 Object* next_candidate = candidate->code()->gc_metadata(); | |
| 469 return reinterpret_cast<SharedFunctionInfo*>(next_candidate); | |
| 470 } | |
| 471 | |
| 472 static void SetNextCandidate(SharedFunctionInfo* candidate, | |
| 473 SharedFunctionInfo* next_candidate) { | |
| 474 candidate->code()->set_gc_metadata(next_candidate); | |
| 475 } | |
| 476 | |
| 477 static void ClearNextCandidate(SharedFunctionInfo* candidate) { | |
| 478 candidate->code()->set_gc_metadata(NULL, SKIP_WRITE_BARRIER); | |
| 479 } | |
| 480 | |
| 481 static SharedFunctionInfo* GetNextCodeMap(SharedFunctionInfo* holder) { | |
| 482 FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); | |
| 483 Object* next_map = code_map->get(SharedFunctionInfo::kNextMapIndex); | |
| 484 return reinterpret_cast<SharedFunctionInfo*>(next_map); | |
| 485 } | |
| 486 | |
| 487 static void SetNextCodeMap(SharedFunctionInfo* holder, | |
| 488 SharedFunctionInfo* next_holder) { | |
| 489 FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); | |
| 490 code_map->set(SharedFunctionInfo::kNextMapIndex, next_holder); | |
| 491 } | |
| 492 | |
| 493 static void ClearNextCodeMap(SharedFunctionInfo* holder) { | |
| 494 FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); | |
| 495 code_map->set_undefined(SharedFunctionInfo::kNextMapIndex); | |
| 496 } | |
| 497 | |
| 498 Isolate* isolate_; | |
| 499 JSFunction* jsfunction_candidates_head_; | |
| 500 SharedFunctionInfo* shared_function_info_candidates_head_; | |
| 501 SharedFunctionInfo* optimized_code_map_holder_head_; | |
| 502 | |
| 503 DISALLOW_COPY_AND_ASSIGN(CodeFlusher); | |
| 504 }; | |
| 505 | |
| 506 | |
| 507 // Defined in isolate.h. | |
| 508 class ThreadLocalTop; | |
| 509 | |
| 510 | |
| 511 // ------------------------------------------------------------------------- | |
| 512 // Mark-Compact collector | |
| 513 class MarkCompactCollector { | |
| 514 public: | |
| 515 // Set the global flags, it must be called before Prepare to take effect. | |
| 516 inline void SetFlags(int flags); | |
| 517 | |
| 518 static void Initialize(); | |
| 519 | |
| 520 void SetUp(); | |
| 521 | |
| 522 void TearDown(); | |
| 523 | |
| 524 void CollectEvacuationCandidates(PagedSpace* space); | |
| 525 | |
| 526 void AddEvacuationCandidate(Page* p); | |
| 527 | |
| 528 // Prepares for GC by resetting relocation info in old and map spaces and | |
| 529 // choosing spaces to compact. | |
| 530 void Prepare(); | |
| 531 | |
| 532 // Performs a global garbage collection. | |
| 533 void CollectGarbage(); | |
| 534 | |
| 535 enum CompactionMode { | |
| 536 INCREMENTAL_COMPACTION, | |
| 537 NON_INCREMENTAL_COMPACTION | |
| 538 }; | |
| 539 | |
| 540 bool StartCompaction(CompactionMode mode); | |
| 541 | |
| 542 void AbortCompaction(); | |
| 543 | |
| 544 #ifdef DEBUG | |
| 545 // Checks whether performing mark-compact collection. | |
| 546 bool in_use() { return state_ > PREPARE_GC; } | |
| 547 bool are_map_pointers_encoded() { return state_ == UPDATE_POINTERS; } | |
| 548 #endif | |
| 549 | |
| 550 // Determine type of object and emit deletion log event. | |
| 551 static void ReportDeleteIfNeeded(HeapObject* obj, Isolate* isolate); | |
| 552 | |
| 553 // Distinguishable invalid map encodings (for single word and multiple words) | |
| 554 // that indicate free regions. | |
| 555 static const uint32_t kSingleFreeEncoding = 0; | |
| 556 static const uint32_t kMultiFreeEncoding = 1; | |
| 557 | |
| 558 static inline bool IsMarked(Object* obj); | |
| 559 | |
| 560 inline Heap* heap() const { return heap_; } | |
| 561 inline Isolate* isolate() const; | |
| 562 | |
| 563 CodeFlusher* code_flusher() { return code_flusher_; } | |
| 564 inline bool is_code_flushing_enabled() const { return code_flusher_ != NULL; } | |
| 565 void EnableCodeFlushing(bool enable); | |
| 566 | |
| 567 enum SweeperType { | |
| 568 PARALLEL_CONSERVATIVE, | |
| 569 CONCURRENT_CONSERVATIVE, | |
| 570 PARALLEL_PRECISE, | |
| 571 CONCURRENT_PRECISE, | |
| 572 PRECISE | |
| 573 }; | |
| 574 | |
| 575 enum SweepingParallelism { | |
| 576 SWEEP_ON_MAIN_THREAD, | |
| 577 SWEEP_IN_PARALLEL | |
| 578 }; | |
| 579 | |
| 580 #ifdef VERIFY_HEAP | |
| 581 void VerifyMarkbitsAreClean(); | |
| 582 static void VerifyMarkbitsAreClean(PagedSpace* space); | |
| 583 static void VerifyMarkbitsAreClean(NewSpace* space); | |
| 584 void VerifyWeakEmbeddedObjectsInCode(); | |
| 585 void VerifyOmittedMapChecks(); | |
| 586 #endif | |
| 587 | |
| 588 // Sweep a single page from the given space conservatively. | |
| 589 // Returns the size of the biggest continuous freed memory chunk in bytes. | |
| 590 template<SweepingParallelism type> | |
| 591 static int SweepConservatively(PagedSpace* space, | |
| 592 FreeList* free_list, | |
| 593 Page* p); | |
| 594 | |
| 595 INLINE(static bool ShouldSkipEvacuationSlotRecording(Object** anchor)) { | |
| 596 return Page::FromAddress(reinterpret_cast<Address>(anchor))-> | |
| 597 ShouldSkipEvacuationSlotRecording(); | |
| 598 } | |
| 599 | |
| 600 INLINE(static bool ShouldSkipEvacuationSlotRecording(Object* host)) { | |
| 601 return Page::FromAddress(reinterpret_cast<Address>(host))-> | |
| 602 ShouldSkipEvacuationSlotRecording(); | |
| 603 } | |
| 604 | |
| 605 INLINE(static bool IsOnEvacuationCandidate(Object* obj)) { | |
| 606 return Page::FromAddress(reinterpret_cast<Address>(obj))-> | |
| 607 IsEvacuationCandidate(); | |
| 608 } | |
| 609 | |
| 610 INLINE(void EvictEvacuationCandidate(Page* page)) { | |
| 611 if (FLAG_trace_fragmentation) { | |
| 612 PrintF("Page %p is too popular. Disabling evacuation.\n", | |
| 613 reinterpret_cast<void*>(page)); | |
| 614 } | |
| 615 | |
| 616 // TODO(gc) If all evacuation candidates are too popular we | |
| 617 // should stop slots recording entirely. | |
| 618 page->ClearEvacuationCandidate(); | |
| 619 | |
| 620 // We were not collecting slots on this page that point | |
| 621 // to other evacuation candidates thus we have to | |
| 622 // rescan the page after evacuation to discover and update all | |
| 623 // pointers to evacuated objects. | |
| 624 if (page->owner()->identity() == OLD_DATA_SPACE) { | |
| 625 evacuation_candidates_.RemoveElement(page); | |
| 626 } else { | |
| 627 page->SetFlag(Page::RESCAN_ON_EVACUATION); | |
| 628 } | |
| 629 } | |
| 630 | |
| 631 void RecordRelocSlot(RelocInfo* rinfo, Object* target); | |
| 632 void RecordCodeEntrySlot(Address slot, Code* target); | |
| 633 void RecordCodeTargetPatch(Address pc, Code* target); | |
| 634 | |
| 635 INLINE(void RecordSlot(Object** anchor_slot, | |
| 636 Object** slot, | |
| 637 Object* object, | |
| 638 SlotsBuffer::AdditionMode mode = | |
| 639 SlotsBuffer::FAIL_ON_OVERFLOW)); | |
| 640 | |
| 641 void MigrateObject(HeapObject* dst, | |
| 642 HeapObject* src, | |
| 643 int size, | |
| 644 AllocationSpace to_old_space); | |
| 645 | |
| 646 bool TryPromoteObject(HeapObject* object, int object_size); | |
| 647 | |
| 648 void InvalidateCode(Code* code); | |
| 649 | |
| 650 void ClearMarkbits(); | |
| 651 | |
| 652 bool abort_incremental_marking() const { return abort_incremental_marking_; } | |
| 653 | |
| 654 bool is_compacting() const { return compacting_; } | |
| 655 | |
| 656 MarkingParity marking_parity() { return marking_parity_; } | |
| 657 | |
| 658 // Concurrent and parallel sweeping support. If required_freed_bytes was set | |
| 659 // to a value larger than 0, then sweeping returns after a block of at least | |
| 660 // required_freed_bytes was freed. If required_freed_bytes was set to zero | |
| 661 // then the whole given space is swept. It returns the size of the maximum | |
| 662 // continuous freed memory chunk. | |
| 663 int SweepInParallel(PagedSpace* space, int required_freed_bytes); | |
| 664 | |
| 665 // Sweeps a given page concurrently to the sweeper threads. It returns the | |
| 666 // size of the maximum continuous freed memory chunk. | |
| 667 int SweepInParallel(Page* page, PagedSpace* space); | |
| 668 | |
| 669 void EnsureSweepingCompleted(); | |
| 670 | |
| 671 // If sweeper threads are not active this method will return true. If | |
| 672 // this is a latency issue we should be smarter here. Otherwise, it will | |
| 673 // return true if the sweeper threads are done processing the pages. | |
| 674 bool IsSweepingCompleted(); | |
| 675 | |
| 676 void RefillFreeList(PagedSpace* space); | |
| 677 | |
| 678 bool AreSweeperThreadsActivated(); | |
| 679 | |
| 680 // Checks if sweeping is in progress right now on any space. | |
| 681 bool sweeping_in_progress() { return sweeping_in_progress_; } | |
| 682 | |
| 683 void set_sequential_sweeping(bool sequential_sweeping) { | |
| 684 sequential_sweeping_ = sequential_sweeping; | |
| 685 } | |
| 686 | |
| 687 bool sequential_sweeping() const { | |
| 688 return sequential_sweeping_; | |
| 689 } | |
| 690 | |
| 691 // Mark the global table which maps weak objects to dependent code without | |
| 692 // marking its contents. | |
| 693 void MarkWeakObjectToCodeTable(); | |
| 694 | |
| 695 // Special case for processing weak references in a full collection. We need | |
| 696 // to artificially keep AllocationSites alive for a time. | |
| 697 void MarkAllocationSite(AllocationSite* site); | |
| 698 | |
| 699 private: | |
| 700 class SweeperTask; | |
| 701 | |
| 702 explicit MarkCompactCollector(Heap* heap); | |
| 703 ~MarkCompactCollector(); | |
| 704 | |
| 705 bool MarkInvalidatedCode(); | |
| 706 bool WillBeDeoptimized(Code* code); | |
| 707 void RemoveDeadInvalidatedCode(); | |
| 708 void ProcessInvalidatedCode(ObjectVisitor* visitor); | |
| 709 | |
| 710 void StartSweeperThreads(); | |
| 711 | |
| 712 #ifdef DEBUG | |
| 713 enum CollectorState { | |
| 714 IDLE, | |
| 715 PREPARE_GC, | |
| 716 MARK_LIVE_OBJECTS, | |
| 717 SWEEP_SPACES, | |
| 718 ENCODE_FORWARDING_ADDRESSES, | |
| 719 UPDATE_POINTERS, | |
| 720 RELOCATE_OBJECTS | |
| 721 }; | |
| 722 | |
| 723 // The current stage of the collector. | |
| 724 CollectorState state_; | |
| 725 #endif | |
| 726 | |
| 727 // Global flag that forces sweeping to be precise, so we can traverse the | |
| 728 // heap. | |
| 729 bool sweep_precisely_; | |
| 730 | |
| 731 bool reduce_memory_footprint_; | |
| 732 | |
| 733 bool abort_incremental_marking_; | |
| 734 | |
| 735 MarkingParity marking_parity_; | |
| 736 | |
| 737 // True if we are collecting slots to perform evacuation from evacuation | |
| 738 // candidates. | |
| 739 bool compacting_; | |
| 740 | |
| 741 bool was_marked_incrementally_; | |
| 742 | |
| 743 // True if concurrent or parallel sweeping is currently in progress. | |
| 744 bool sweeping_in_progress_; | |
| 745 | |
| 746 base::Semaphore pending_sweeper_jobs_semaphore_; | |
| 747 | |
| 748 bool sequential_sweeping_; | |
| 749 | |
| 750 SlotsBufferAllocator slots_buffer_allocator_; | |
| 751 | |
| 752 SlotsBuffer* migration_slots_buffer_; | |
| 753 | |
| 754 // Finishes GC, performs heap verification if enabled. | |
| 755 void Finish(); | |
| 756 | |
| 757 // ----------------------------------------------------------------------- | |
| 758 // Phase 1: Marking live objects. | |
| 759 // | |
| 760 // Before: The heap has been prepared for garbage collection by | |
| 761 // MarkCompactCollector::Prepare() and is otherwise in its | |
| 762 // normal state. | |
| 763 // | |
| 764 // After: Live objects are marked and non-live objects are unmarked. | |
| 765 | |
| 766 friend class RootMarkingVisitor; | |
| 767 friend class MarkingVisitor; | |
| 768 friend class MarkCompactMarkingVisitor; | |
| 769 friend class CodeMarkingVisitor; | |
| 770 friend class SharedFunctionInfoMarkingVisitor; | |
| 771 | |
| 772 // Mark code objects that are active on the stack to prevent them | |
| 773 // from being flushed. | |
| 774 void PrepareThreadForCodeFlushing(Isolate* isolate, ThreadLocalTop* top); | |
| 775 | |
| 776 void PrepareForCodeFlushing(); | |
| 777 | |
| 778 // Marking operations for objects reachable from roots. | |
| 779 void MarkLiveObjects(); | |
| 780 | |
| 781 void AfterMarking(); | |
| 782 | |
| 783 // Marks the object black and pushes it on the marking stack. | |
| 784 // This is for non-incremental marking only. | |
| 785 INLINE(void MarkObject(HeapObject* obj, MarkBit mark_bit)); | |
| 786 | |
| 787 // Marks the object black assuming that it is not yet marked. | |
| 788 // This is for non-incremental marking only. | |
| 789 INLINE(void SetMark(HeapObject* obj, MarkBit mark_bit)); | |
| 790 | |
| 791 // Mark the heap roots and all objects reachable from them. | |
| 792 void MarkRoots(RootMarkingVisitor* visitor); | |
| 793 | |
| 794 // Mark the string table specially. References to internalized strings from | |
| 795 // the string table are weak. | |
| 796 void MarkStringTable(RootMarkingVisitor* visitor); | |
| 797 | |
| 798 // Mark objects in implicit references groups if their parent object | |
| 799 // is marked. | |
| 800 void MarkImplicitRefGroups(); | |
| 801 | |
| 802 // Mark objects reachable (transitively) from objects in the marking stack | |
| 803 // or overflowed in the heap. | |
| 804 void ProcessMarkingDeque(); | |
| 805 | |
| 806 // Mark objects reachable (transitively) from objects in the marking stack | |
| 807 // or overflowed in the heap. This respects references only considered in | |
| 808 // the final atomic marking pause including the following: | |
| 809 // - Processing of objects reachable through Harmony WeakMaps. | |
| 810 // - Objects reachable due to host application logic like object groups | |
| 811 // or implicit references' groups. | |
| 812 void ProcessEphemeralMarking(ObjectVisitor* visitor); | |
| 813 | |
| 814 // If the call-site of the top optimized code was not prepared for | |
| 815 // deoptimization, then treat the maps in the code as strong pointers, | |
| 816 // otherwise a map can die and deoptimize the code. | |
| 817 void ProcessTopOptimizedFrame(ObjectVisitor* visitor); | |
| 818 | |
| 819 // Mark objects reachable (transitively) from objects in the marking | |
| 820 // stack. This function empties the marking stack, but may leave | |
| 821 // overflowed objects in the heap, in which case the marking stack's | |
| 822 // overflow flag will be set. | |
| 823 void EmptyMarkingDeque(); | |
| 824 | |
| 825 // Refill the marking stack with overflowed objects from the heap. This | |
| 826 // function either leaves the marking stack full or clears the overflow | |
| 827 // flag on the marking stack. | |
| 828 void RefillMarkingDeque(); | |
| 829 | |
| 830 // After reachable maps have been marked process per context object | |
| 831 // literal map caches removing unmarked entries. | |
| 832 void ProcessMapCaches(); | |
| 833 | |
| 834 // Callback function for telling whether the object *p is an unmarked | |
| 835 // heap object. | |
| 836 static bool IsUnmarkedHeapObject(Object** p); | |
| 837 static bool IsUnmarkedHeapObjectWithHeap(Heap* heap, Object** p); | |
| 838 | |
| 839 // Map transitions from a live map to a dead map must be killed. | |
| 840 // We replace them with a null descriptor, with the same key. | |
| 841 void ClearNonLiveReferences(); | |
| 842 void ClearNonLivePrototypeTransitions(Map* map); | |
| 843 void ClearNonLiveMapTransitions(Map* map, MarkBit map_mark); | |
| 844 | |
| 845 void ClearDependentCode(DependentCode* dependent_code); | |
| 846 void ClearDependentICList(Object* head); | |
| 847 void ClearNonLiveDependentCode(DependentCode* dependent_code); | |
| 848 int ClearNonLiveDependentCodeInGroup(DependentCode* dependent_code, int group, | |
| 849 int start, int end, int new_start); | |
| 850 | |
| 851 // Mark all values associated with reachable keys in weak collections | |
| 852 // encountered so far. This might push new object or even new weak maps onto | |
| 853 // the marking stack. | |
| 854 void ProcessWeakCollections(); | |
| 855 | |
| 856 // After all reachable objects have been marked those weak map entries | |
| 857 // with an unreachable key are removed from all encountered weak maps. | |
| 858 // The linked list of all encountered weak maps is destroyed. | |
| 859 void ClearWeakCollections(); | |
| 860 | |
| 861 // ----------------------------------------------------------------------- | |
| 862 // Phase 2: Sweeping to clear mark bits and free non-live objects for | |
| 863 // a non-compacting collection. | |
| 864 // | |
| 865 // Before: Live objects are marked and non-live objects are unmarked. | |
| 866 // | |
| 867 // After: Live objects are unmarked, non-live regions have been added to | |
| 868 // their space's free list. Active eden semispace is compacted by | |
| 869 // evacuation. | |
| 870 // | |
| 871 | |
| 872 // If we are not compacting the heap, we simply sweep the spaces except | |
| 873 // for the large object space, clearing mark bits and adding unmarked | |
| 874 // regions to each space's free list. | |
| 875 void SweepSpaces(); | |
| 876 | |
| 877 int DiscoverAndEvacuateBlackObjectsOnPage(NewSpace* new_space, | |
| 878 NewSpacePage* p); | |
| 879 | |
| 880 void EvacuateNewSpace(); | |
| 881 | |
| 882 void EvacuateLiveObjectsFromPage(Page* p); | |
| 883 | |
| 884 void EvacuatePages(); | |
| 885 | |
| 886 void EvacuateNewSpaceAndCandidates(); | |
| 887 | |
| 888 void ReleaseEvacuationCandidates(); | |
| 889 | |
| 890 // Moves the pages of the evacuation_candidates_ list to the end of their | |
| 891 // corresponding space pages list. | |
| 892 void MoveEvacuationCandidatesToEndOfPagesList(); | |
| 893 | |
| 894 void SweepSpace(PagedSpace* space, SweeperType sweeper); | |
| 895 | |
| 896 // Finalizes the parallel sweeping phase. Marks all the pages that were | |
| 897 // swept in parallel. | |
| 898 void ParallelSweepSpacesComplete(); | |
| 899 | |
| 900 void ParallelSweepSpaceComplete(PagedSpace* space); | |
| 901 | |
| 902 // Updates store buffer and slot buffer for a pointer in a migrating object. | |
| 903 void RecordMigratedSlot(Object* value, Address slot); | |
| 904 | |
| 905 #ifdef DEBUG | |
| 906 friend class MarkObjectVisitor; | |
| 907 static void VisitObject(HeapObject* obj); | |
| 908 | |
| 909 friend class UnmarkObjectVisitor; | |
| 910 static void UnmarkObject(HeapObject* obj); | |
| 911 #endif | |
| 912 | |
| 913 Heap* heap_; | |
| 914 MarkingDeque marking_deque_; | |
| 915 CodeFlusher* code_flusher_; | |
| 916 bool have_code_to_deoptimize_; | |
| 917 | |
| 918 List<Page*> evacuation_candidates_; | |
| 919 List<Code*> invalidated_code_; | |
| 920 | |
| 921 SmartPointer<FreeList> free_list_old_data_space_; | |
| 922 SmartPointer<FreeList> free_list_old_pointer_space_; | |
| 923 | |
| 924 friend class Heap; | |
| 925 }; | |
| 926 | |
| 927 | |
| 928 class MarkBitCellIterator BASE_EMBEDDED { | |
| 929 public: | |
| 930 explicit MarkBitCellIterator(MemoryChunk* chunk) | |
| 931 : chunk_(chunk) { | |
| 932 last_cell_index_ = Bitmap::IndexToCell( | |
| 933 Bitmap::CellAlignIndex( | |
| 934 chunk_->AddressToMarkbitIndex(chunk_->area_end()))); | |
| 935 cell_base_ = chunk_->area_start(); | |
| 936 cell_index_ = Bitmap::IndexToCell( | |
| 937 Bitmap::CellAlignIndex( | |
| 938 chunk_->AddressToMarkbitIndex(cell_base_))); | |
| 939 cells_ = chunk_->markbits()->cells(); | |
| 940 } | |
| 941 | |
| 942 inline bool Done() { return cell_index_ == last_cell_index_; } | |
| 943 | |
| 944 inline bool HasNext() { return cell_index_ < last_cell_index_ - 1; } | |
| 945 | |
| 946 inline MarkBit::CellType* CurrentCell() { | |
| 947 DCHECK(cell_index_ == Bitmap::IndexToCell(Bitmap::CellAlignIndex( | |
| 948 chunk_->AddressToMarkbitIndex(cell_base_)))); | |
| 949 return &cells_[cell_index_]; | |
| 950 } | |
| 951 | |
| 952 inline Address CurrentCellBase() { | |
| 953 DCHECK(cell_index_ == Bitmap::IndexToCell(Bitmap::CellAlignIndex( | |
| 954 chunk_->AddressToMarkbitIndex(cell_base_)))); | |
| 955 return cell_base_; | |
| 956 } | |
| 957 | |
| 958 inline void Advance() { | |
| 959 cell_index_++; | |
| 960 cell_base_ += 32 * kPointerSize; | |
| 961 } | |
| 962 | |
| 963 private: | |
| 964 MemoryChunk* chunk_; | |
| 965 MarkBit::CellType* cells_; | |
| 966 unsigned int last_cell_index_; | |
| 967 unsigned int cell_index_; | |
| 968 Address cell_base_; | |
| 969 }; | |
| 970 | |
| 971 | |
| 972 class SequentialSweepingScope BASE_EMBEDDED { | |
| 973 public: | |
| 974 explicit SequentialSweepingScope(MarkCompactCollector *collector) : | |
| 975 collector_(collector) { | |
| 976 collector_->set_sequential_sweeping(true); | |
| 977 } | |
| 978 | |
| 979 ~SequentialSweepingScope() { | |
| 980 collector_->set_sequential_sweeping(false); | |
| 981 } | |
| 982 | |
| 983 private: | |
| 984 MarkCompactCollector* collector_; | |
| 985 }; | |
| 986 | |
| 987 | |
| 988 const char* AllocationSpaceName(AllocationSpace space); | |
| 989 | |
| 990 } } // namespace v8::internal | |
| 991 | |
| 992 #endif // V8_MARK_COMPACT_H_ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 437993003:
Move a bunch of GC related files to heap/ subdirectory (Closed)
Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge