1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "concurrent_copying.h" 18 19 #include "art_field-inl.h" 20 #include "gc/accounting/heap_bitmap-inl.h" 21 #include "gc/accounting/space_bitmap-inl.h" 22 #include "gc/space/image_space.h" 23 #include "gc/space/space.h" 24 #include "intern_table.h" 25 #include "mirror/class-inl.h" 26 #include "mirror/object-inl.h" 27 #include "scoped_thread_state_change.h" 28 #include "thread-inl.h" 29 #include "thread_list.h" 30 #include "well_known_classes.h" 31 32 namespace art { 33 namespace gc { 34 namespace collector { 35 36 ConcurrentCopying::ConcurrentCopying(Heap* heap, const std::string& name_prefix) 37 : GarbageCollector(heap, 38 name_prefix + (name_prefix.empty() ? "" : " ") + 39 "concurrent copying + mark sweep"), 40 region_space_(nullptr), gc_barrier_(new Barrier(0)), mark_queue_(2 * MB), 41 is_marking_(false), is_active_(false), is_asserting_to_space_invariant_(false), 42 heap_mark_bitmap_(nullptr), live_stack_freeze_size_(0), 43 skipped_blocks_lock_("concurrent copying bytes blocks lock", kMarkSweepMarkStackLock), 44 rb_table_(heap_->GetReadBarrierTable()), 45 force_evacuate_all_(false) { 46 static_assert(space::RegionSpace::kRegionSize == accounting::ReadBarrierTable::kRegionSize, 47 "The region space size and the read barrier table region size must match"); 48 cc_heap_bitmap_.reset(new accounting::HeapBitmap(heap)); 49 { 50 Thread* self = Thread::Current(); 51 ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_); 52 // Cache this so that we won't have to lock heap_bitmap_lock_ in 53 // Mark() which could cause a nested lock on heap_bitmap_lock_ 54 // when GC causes a RB while doing GC or a lock order violation 55 // (class_linker_lock_ and heap_bitmap_lock_). 56 heap_mark_bitmap_ = heap->GetMarkBitmap(); 57 } 58 } 59 60 ConcurrentCopying::~ConcurrentCopying() { 61 } 62 63 void ConcurrentCopying::RunPhases() { 64 CHECK(kUseBakerReadBarrier || kUseTableLookupReadBarrier); 65 CHECK(!is_active_); 66 is_active_ = true; 67 Thread* self = Thread::Current(); 68 Locks::mutator_lock_->AssertNotHeld(self); 69 { 70 ReaderMutexLock mu(self, *Locks::mutator_lock_); 71 InitializePhase(); 72 } 73 FlipThreadRoots(); 74 { 75 ReaderMutexLock mu(self, *Locks::mutator_lock_); 76 MarkingPhase(); 77 } 78 // Verify no from space refs. This causes a pause. 79 if (kEnableNoFromSpaceRefsVerification || kIsDebugBuild) { 80 TimingLogger::ScopedTiming split("(Paused)VerifyNoFromSpaceReferences", GetTimings()); 81 ScopedPause pause(this); 82 CheckEmptyMarkQueue(); 83 if (kVerboseMode) { 84 LOG(INFO) << "Verifying no from-space refs"; 85 } 86 VerifyNoFromSpaceReferences(); 87 if (kVerboseMode) { 88 LOG(INFO) << "Done verifying no from-space refs"; 89 } 90 CheckEmptyMarkQueue(); 91 } 92 { 93 ReaderMutexLock mu(self, *Locks::mutator_lock_); 94 ReclaimPhase(); 95 } 96 FinishPhase(); 97 CHECK(is_active_); 98 is_active_ = false; 99 } 100 101 void ConcurrentCopying::BindBitmaps() { 102 Thread* self = Thread::Current(); 103 WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); 104 // Mark all of the spaces we never collect as immune. 105 for (const auto& space : heap_->GetContinuousSpaces()) { 106 if (space->GetGcRetentionPolicy() == space::kGcRetentionPolicyNeverCollect 107 || space->GetGcRetentionPolicy() == space::kGcRetentionPolicyFullCollect) { 108 CHECK(space->IsZygoteSpace() || space->IsImageSpace()); 109 CHECK(immune_region_.AddContinuousSpace(space)) << "Failed to add space " << *space; 110 const char* bitmap_name = space->IsImageSpace() ? "cc image space bitmap" : 111 "cc zygote space bitmap"; 112 // TODO: try avoiding using bitmaps for image/zygote to save space. 113 accounting::ContinuousSpaceBitmap* bitmap = 114 accounting::ContinuousSpaceBitmap::Create(bitmap_name, space->Begin(), space->Capacity()); 115 cc_heap_bitmap_->AddContinuousSpaceBitmap(bitmap); 116 cc_bitmaps_.push_back(bitmap); 117 } else if (space == region_space_) { 118 accounting::ContinuousSpaceBitmap* bitmap = 119 accounting::ContinuousSpaceBitmap::Create("cc region space bitmap", 120 space->Begin(), space->Capacity()); 121 cc_heap_bitmap_->AddContinuousSpaceBitmap(bitmap); 122 cc_bitmaps_.push_back(bitmap); 123 region_space_bitmap_ = bitmap; 124 } 125 } 126 } 127 128 void ConcurrentCopying::InitializePhase() { 129 TimingLogger::ScopedTiming split("InitializePhase", GetTimings()); 130 if (kVerboseMode) { 131 LOG(INFO) << "GC InitializePhase"; 132 LOG(INFO) << "Region-space : " << reinterpret_cast<void*>(region_space_->Begin()) << "-" 133 << reinterpret_cast<void*>(region_space_->Limit()); 134 } 135 CHECK(mark_queue_.IsEmpty()); 136 immune_region_.Reset(); 137 bytes_moved_.StoreRelaxed(0); 138 objects_moved_.StoreRelaxed(0); 139 if (GetCurrentIteration()->GetGcCause() == kGcCauseExplicit || 140 GetCurrentIteration()->GetGcCause() == kGcCauseForNativeAlloc || 141 GetCurrentIteration()->GetClearSoftReferences()) { 142 force_evacuate_all_ = true; 143 } else { 144 force_evacuate_all_ = false; 145 } 146 BindBitmaps(); 147 if (kVerboseMode) { 148 LOG(INFO) << "force_evacuate_all=" << force_evacuate_all_; 149 LOG(INFO) << "Immune region: " << immune_region_.Begin() << "-" << immune_region_.End(); 150 LOG(INFO) << "GC end of InitializePhase"; 151 } 152 } 153 154 // Used to switch the thread roots of a thread from from-space refs to to-space refs. 155 class ThreadFlipVisitor : public Closure { 156 public: 157 explicit ThreadFlipVisitor(ConcurrentCopying* concurrent_copying, bool use_tlab) 158 : concurrent_copying_(concurrent_copying), use_tlab_(use_tlab) { 159 } 160 161 virtual void Run(Thread* thread) OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 162 // Note: self is not necessarily equal to thread since thread may be suspended. 163 Thread* self = Thread::Current(); 164 CHECK(thread == self || thread->IsSuspended() || thread->GetState() == kWaitingPerformingGc) 165 << thread->GetState() << " thread " << thread << " self " << self; 166 if (use_tlab_ && thread->HasTlab()) { 167 if (ConcurrentCopying::kEnableFromSpaceAccountingCheck) { 168 // This must come before the revoke. 169 size_t thread_local_objects = thread->GetThreadLocalObjectsAllocated(); 170 concurrent_copying_->region_space_->RevokeThreadLocalBuffers(thread); 171 reinterpret_cast<Atomic<size_t>*>(&concurrent_copying_->from_space_num_objects_at_first_pause_)-> 172 FetchAndAddSequentiallyConsistent(thread_local_objects); 173 } else { 174 concurrent_copying_->region_space_->RevokeThreadLocalBuffers(thread); 175 } 176 } 177 if (kUseThreadLocalAllocationStack) { 178 thread->RevokeThreadLocalAllocationStack(); 179 } 180 ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_); 181 thread->VisitRoots(concurrent_copying_); 182 concurrent_copying_->GetBarrier().Pass(self); 183 } 184 185 private: 186 ConcurrentCopying* const concurrent_copying_; 187 const bool use_tlab_; 188 }; 189 190 // Called back from Runtime::FlipThreadRoots() during a pause. 191 class FlipCallback : public Closure { 192 public: 193 explicit FlipCallback(ConcurrentCopying* concurrent_copying) 194 : concurrent_copying_(concurrent_copying) { 195 } 196 197 virtual void Run(Thread* thread) OVERRIDE EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_) { 198 ConcurrentCopying* cc = concurrent_copying_; 199 TimingLogger::ScopedTiming split("(Paused)FlipCallback", cc->GetTimings()); 200 // Note: self is not necessarily equal to thread since thread may be suspended. 201 Thread* self = Thread::Current(); 202 CHECK(thread == self); 203 Locks::mutator_lock_->AssertExclusiveHeld(self); 204 cc->region_space_->SetFromSpace(cc->rb_table_, cc->force_evacuate_all_); 205 cc->SwapStacks(self); 206 if (ConcurrentCopying::kEnableFromSpaceAccountingCheck) { 207 cc->RecordLiveStackFreezeSize(self); 208 cc->from_space_num_objects_at_first_pause_ = cc->region_space_->GetObjectsAllocated(); 209 cc->from_space_num_bytes_at_first_pause_ = cc->region_space_->GetBytesAllocated(); 210 } 211 cc->is_marking_ = true; 212 if (UNLIKELY(Runtime::Current()->IsActiveTransaction())) { 213 CHECK(Runtime::Current()->IsAotCompiler()); 214 TimingLogger::ScopedTiming split2("(Paused)VisitTransactionRoots", cc->GetTimings()); 215 Runtime::Current()->VisitTransactionRoots(cc); 216 } 217 } 218 219 private: 220 ConcurrentCopying* const concurrent_copying_; 221 }; 222 223 // Switch threads that from from-space to to-space refs. Forward/mark the thread roots. 224 void ConcurrentCopying::FlipThreadRoots() { 225 TimingLogger::ScopedTiming split("FlipThreadRoots", GetTimings()); 226 if (kVerboseMode) { 227 LOG(INFO) << "time=" << region_space_->Time(); 228 region_space_->DumpNonFreeRegions(LOG(INFO)); 229 } 230 Thread* self = Thread::Current(); 231 Locks::mutator_lock_->AssertNotHeld(self); 232 gc_barrier_->Init(self, 0); 233 ThreadFlipVisitor thread_flip_visitor(this, heap_->use_tlab_); 234 FlipCallback flip_callback(this); 235 size_t barrier_count = Runtime::Current()->FlipThreadRoots( 236 &thread_flip_visitor, &flip_callback, this); 237 { 238 ScopedThreadStateChange tsc(self, kWaitingForCheckPointsToRun); 239 gc_barrier_->Increment(self, barrier_count); 240 } 241 is_asserting_to_space_invariant_ = true; 242 QuasiAtomic::ThreadFenceForConstructor(); 243 if (kVerboseMode) { 244 LOG(INFO) << "time=" << region_space_->Time(); 245 region_space_->DumpNonFreeRegions(LOG(INFO)); 246 LOG(INFO) << "GC end of FlipThreadRoots"; 247 } 248 } 249 250 void ConcurrentCopying::SwapStacks(Thread* self) { 251 heap_->SwapStacks(self); 252 } 253 254 void ConcurrentCopying::RecordLiveStackFreezeSize(Thread* self) { 255 WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); 256 live_stack_freeze_size_ = heap_->GetLiveStack()->Size(); 257 } 258 259 // Used to visit objects in the immune spaces. 260 class ConcurrentCopyingImmuneSpaceObjVisitor { 261 public: 262 explicit ConcurrentCopyingImmuneSpaceObjVisitor(ConcurrentCopying* cc) 263 : collector_(cc) {} 264 265 void operator()(mirror::Object* obj) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 266 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) { 267 DCHECK(obj != nullptr); 268 DCHECK(collector_->immune_region_.ContainsObject(obj)); 269 accounting::ContinuousSpaceBitmap* cc_bitmap = 270 collector_->cc_heap_bitmap_->GetContinuousSpaceBitmap(obj); 271 DCHECK(cc_bitmap != nullptr) 272 << "An immune space object must have a bitmap"; 273 if (kIsDebugBuild) { 274 DCHECK(collector_->heap_->GetMarkBitmap()->Test(obj)) 275 << "Immune space object must be already marked"; 276 } 277 // This may or may not succeed, which is ok. 278 if (kUseBakerReadBarrier) { 279 obj->AtomicSetReadBarrierPointer(ReadBarrier::WhitePtr(), ReadBarrier::GrayPtr()); 280 } 281 if (cc_bitmap->AtomicTestAndSet(obj)) { 282 // Already marked. Do nothing. 283 } else { 284 // Newly marked. Set the gray bit and push it onto the mark stack. 285 CHECK(!kUseBakerReadBarrier || obj->GetReadBarrierPointer() == ReadBarrier::GrayPtr()); 286 collector_->PushOntoMarkStack<true>(obj); 287 } 288 } 289 290 private: 291 ConcurrentCopying* collector_; 292 }; 293 294 class EmptyCheckpoint : public Closure { 295 public: 296 explicit EmptyCheckpoint(ConcurrentCopying* concurrent_copying) 297 : concurrent_copying_(concurrent_copying) { 298 } 299 300 virtual void Run(Thread* thread) OVERRIDE NO_THREAD_SAFETY_ANALYSIS { 301 // Note: self is not necessarily equal to thread since thread may be suspended. 302 Thread* self = Thread::Current(); 303 CHECK(thread == self || thread->IsSuspended() || thread->GetState() == kWaitingPerformingGc) 304 << thread->GetState() << " thread " << thread << " self " << self; 305 // If thread is a running mutator, then act on behalf of the garbage collector. 306 // See the code in ThreadList::RunCheckpoint. 307 if (thread->GetState() == kRunnable) { 308 concurrent_copying_->GetBarrier().Pass(self); 309 } 310 } 311 312 private: 313 ConcurrentCopying* const concurrent_copying_; 314 }; 315 316 // Concurrently mark roots that are guarded by read barriers and process the mark stack. 317 void ConcurrentCopying::MarkingPhase() { 318 TimingLogger::ScopedTiming split("MarkingPhase", GetTimings()); 319 if (kVerboseMode) { 320 LOG(INFO) << "GC MarkingPhase"; 321 } 322 { 323 // Mark the image root. The WB-based collectors do not need to 324 // scan the image objects from roots by relying on the card table, 325 // but it's necessary for the RB to-space invariant to hold. 326 TimingLogger::ScopedTiming split1("VisitImageRoots", GetTimings()); 327 gc::space::ImageSpace* image = heap_->GetImageSpace(); 328 if (image != nullptr) { 329 mirror::ObjectArray<mirror::Object>* image_root = image->GetImageHeader().GetImageRoots(); 330 mirror::Object* marked_image_root = Mark(image_root); 331 CHECK_EQ(image_root, marked_image_root) << "An image object does not move"; 332 if (ReadBarrier::kEnableToSpaceInvariantChecks) { 333 AssertToSpaceInvariant(nullptr, MemberOffset(0), marked_image_root); 334 } 335 } 336 } 337 { 338 TimingLogger::ScopedTiming split2("VisitConstantRoots", GetTimings()); 339 Runtime::Current()->VisitConstantRoots(this); 340 } 341 { 342 TimingLogger::ScopedTiming split3("VisitInternTableRoots", GetTimings()); 343 Runtime::Current()->GetInternTable()->VisitRoots(this, kVisitRootFlagAllRoots); 344 } 345 { 346 TimingLogger::ScopedTiming split4("VisitClassLinkerRoots", GetTimings()); 347 Runtime::Current()->GetClassLinker()->VisitRoots(this, kVisitRootFlagAllRoots); 348 } 349 { 350 // TODO: don't visit the transaction roots if it's not active. 351 TimingLogger::ScopedTiming split5("VisitNonThreadRoots", GetTimings()); 352 Runtime::Current()->VisitNonThreadRoots(this); 353 } 354 355 // Immune spaces. 356 for (auto& space : heap_->GetContinuousSpaces()) { 357 if (immune_region_.ContainsSpace(space)) { 358 DCHECK(space->IsImageSpace() || space->IsZygoteSpace()); 359 accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap(); 360 ConcurrentCopyingImmuneSpaceObjVisitor visitor(this); 361 live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()), 362 reinterpret_cast<uintptr_t>(space->Limit()), 363 visitor); 364 } 365 } 366 367 Thread* self = Thread::Current(); 368 { 369 TimingLogger::ScopedTiming split6("ProcessMarkStack", GetTimings()); 370 // Process the mark stack and issue an empty check point. If the 371 // mark stack is still empty after the check point, we're 372 // done. Otherwise, repeat. 373 ProcessMarkStack(); 374 size_t count = 0; 375 while (!ProcessMarkStack()) { 376 ++count; 377 if (kVerboseMode) { 378 LOG(INFO) << "Issue an empty check point. " << count; 379 } 380 IssueEmptyCheckpoint(); 381 } 382 // Need to ensure the mark stack is empty before reference 383 // processing to get rid of non-reference gray objects. 384 CheckEmptyMarkQueue(); 385 // Enable the GetReference slow path and disallow access to the system weaks. 386 GetHeap()->GetReferenceProcessor()->EnableSlowPath(); 387 Runtime::Current()->DisallowNewSystemWeaks(); 388 QuasiAtomic::ThreadFenceForConstructor(); 389 // Lock-unlock the system weak locks so that there's no thread in 390 // the middle of accessing system weaks. 391 Runtime::Current()->EnsureNewSystemWeaksDisallowed(); 392 // Note: Do not issue a checkpoint from here to the 393 // SweepSystemWeaks call or else a deadlock due to 394 // WaitHoldingLocks() would occur. 395 if (kVerboseMode) { 396 LOG(INFO) << "Enabled the ref proc slow path & disabled access to system weaks."; 397 LOG(INFO) << "ProcessReferences"; 398 } 399 ProcessReferences(self, true); 400 CheckEmptyMarkQueue(); 401 if (kVerboseMode) { 402 LOG(INFO) << "SweepSystemWeaks"; 403 } 404 SweepSystemWeaks(self); 405 if (kVerboseMode) { 406 LOG(INFO) << "SweepSystemWeaks done"; 407 } 408 // Because hash_set::Erase() can call the hash function for 409 // arbitrary elements in the weak intern table in 410 // InternTable::Table::SweepWeaks(), the above SweepSystemWeaks() 411 // call may have marked some objects (strings) alive. So process 412 // the mark stack here once again. 413 ProcessMarkStack(); 414 CheckEmptyMarkQueue(); 415 // Disable marking. 416 if (kUseTableLookupReadBarrier) { 417 heap_->rb_table_->ClearAll(); 418 DCHECK(heap_->rb_table_->IsAllCleared()); 419 } 420 is_mark_queue_push_disallowed_.StoreSequentiallyConsistent(1); 421 is_marking_ = false; 422 if (kVerboseMode) { 423 LOG(INFO) << "AllowNewSystemWeaks"; 424 } 425 Runtime::Current()->AllowNewSystemWeaks(); 426 CheckEmptyMarkQueue(); 427 } 428 429 if (kVerboseMode) { 430 LOG(INFO) << "GC end of MarkingPhase"; 431 } 432 } 433 434 void ConcurrentCopying::IssueEmptyCheckpoint() { 435 Thread* self = Thread::Current(); 436 EmptyCheckpoint check_point(this); 437 ThreadList* thread_list = Runtime::Current()->GetThreadList(); 438 gc_barrier_->Init(self, 0); 439 size_t barrier_count = thread_list->RunCheckpoint(&check_point); 440 // If there are no threads to wait which implys that all the checkpoint functions are finished, 441 // then no need to release the mutator lock. 442 if (barrier_count == 0) { 443 return; 444 } 445 // Release locks then wait for all mutator threads to pass the barrier. 446 Locks::mutator_lock_->SharedUnlock(self); 447 { 448 ScopedThreadStateChange tsc(self, kWaitingForCheckPointsToRun); 449 gc_barrier_->Increment(self, barrier_count); 450 } 451 Locks::mutator_lock_->SharedLock(self); 452 } 453 454 mirror::Object* ConcurrentCopying::PopOffMarkStack() { 455 return mark_queue_.Dequeue(); 456 } 457 458 template<bool kThreadSafe> 459 void ConcurrentCopying::PushOntoMarkStack(mirror::Object* to_ref) { 460 CHECK_EQ(is_mark_queue_push_disallowed_.LoadRelaxed(), 0) 461 << " " << to_ref << " " << PrettyTypeOf(to_ref); 462 if (kThreadSafe) { 463 CHECK(mark_queue_.Enqueue(to_ref)) << "Mark queue overflow"; 464 } else { 465 CHECK(mark_queue_.EnqueueThreadUnsafe(to_ref)) << "Mark queue overflow"; 466 } 467 } 468 469 accounting::ObjectStack* ConcurrentCopying::GetAllocationStack() { 470 return heap_->allocation_stack_.get(); 471 } 472 473 accounting::ObjectStack* ConcurrentCopying::GetLiveStack() { 474 return heap_->live_stack_.get(); 475 } 476 477 inline mirror::Object* ConcurrentCopying::GetFwdPtr(mirror::Object* from_ref) { 478 DCHECK(region_space_->IsInFromSpace(from_ref)); 479 LockWord lw = from_ref->GetLockWord(false); 480 if (lw.GetState() == LockWord::kForwardingAddress) { 481 mirror::Object* fwd_ptr = reinterpret_cast<mirror::Object*>(lw.ForwardingAddress()); 482 CHECK(fwd_ptr != nullptr); 483 return fwd_ptr; 484 } else { 485 return nullptr; 486 } 487 } 488 489 // The following visitors are that used to verify that there's no 490 // references to the from-space left after marking. 491 class ConcurrentCopyingVerifyNoFromSpaceRefsVisitor : public SingleRootVisitor { 492 public: 493 explicit ConcurrentCopyingVerifyNoFromSpaceRefsVisitor(ConcurrentCopying* collector) 494 : collector_(collector) {} 495 496 void operator()(mirror::Object* ref) const 497 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 498 if (ref == nullptr) { 499 // OK. 500 return; 501 } 502 collector_->AssertToSpaceInvariant(nullptr, MemberOffset(0), ref); 503 if (kUseBakerReadBarrier) { 504 if (collector_->RegionSpace()->IsInToSpace(ref)) { 505 CHECK(ref->GetReadBarrierPointer() == nullptr) 506 << "To-space ref " << ref << " " << PrettyTypeOf(ref) 507 << " has non-white rb_ptr " << ref->GetReadBarrierPointer(); 508 } else { 509 CHECK(ref->GetReadBarrierPointer() == ReadBarrier::BlackPtr() || 510 (ref->GetReadBarrierPointer() == ReadBarrier::WhitePtr() && 511 collector_->IsOnAllocStack(ref))) 512 << "Non-moving/unevac from space ref " << ref << " " << PrettyTypeOf(ref) 513 << " has non-black rb_ptr " << ref->GetReadBarrierPointer() 514 << " but isn't on the alloc stack (and has white rb_ptr)." 515 << " Is it in the non-moving space=" 516 << (collector_->GetHeap()->GetNonMovingSpace()->HasAddress(ref)); 517 } 518 } 519 } 520 521 void VisitRoot(mirror::Object* root, const RootInfo& info ATTRIBUTE_UNUSED) 522 OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 523 DCHECK(root != nullptr); 524 operator()(root); 525 } 526 527 private: 528 ConcurrentCopying* const collector_; 529 }; 530 531 class ConcurrentCopyingVerifyNoFromSpaceRefsFieldVisitor { 532 public: 533 explicit ConcurrentCopyingVerifyNoFromSpaceRefsFieldVisitor(ConcurrentCopying* collector) 534 : collector_(collector) {} 535 536 void operator()(mirror::Object* obj, MemberOffset offset, bool /* is_static */) const 537 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 538 mirror::Object* ref = 539 obj->GetFieldObject<mirror::Object, kDefaultVerifyFlags, kWithoutReadBarrier>(offset); 540 ConcurrentCopyingVerifyNoFromSpaceRefsVisitor visitor(collector_); 541 visitor(ref); 542 } 543 void operator()(mirror::Class* klass, mirror::Reference* ref) const 544 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 545 CHECK(klass->IsTypeOfReferenceClass()); 546 this->operator()(ref, mirror::Reference::ReferentOffset(), false); 547 } 548 549 private: 550 ConcurrentCopying* collector_; 551 }; 552 553 class ConcurrentCopyingVerifyNoFromSpaceRefsObjectVisitor { 554 public: 555 explicit ConcurrentCopyingVerifyNoFromSpaceRefsObjectVisitor(ConcurrentCopying* collector) 556 : collector_(collector) {} 557 void operator()(mirror::Object* obj) const 558 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 559 ObjectCallback(obj, collector_); 560 } 561 static void ObjectCallback(mirror::Object* obj, void *arg) 562 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 563 CHECK(obj != nullptr); 564 ConcurrentCopying* collector = reinterpret_cast<ConcurrentCopying*>(arg); 565 space::RegionSpace* region_space = collector->RegionSpace(); 566 CHECK(!region_space->IsInFromSpace(obj)) << "Scanning object " << obj << " in from space"; 567 ConcurrentCopyingVerifyNoFromSpaceRefsFieldVisitor visitor(collector); 568 obj->VisitReferences<true>(visitor, visitor); 569 if (kUseBakerReadBarrier) { 570 if (collector->RegionSpace()->IsInToSpace(obj)) { 571 CHECK(obj->GetReadBarrierPointer() == nullptr) 572 << "obj=" << obj << " non-white rb_ptr " << obj->GetReadBarrierPointer(); 573 } else { 574 CHECK(obj->GetReadBarrierPointer() == ReadBarrier::BlackPtr() || 575 (obj->GetReadBarrierPointer() == ReadBarrier::WhitePtr() && 576 collector->IsOnAllocStack(obj))) 577 << "Non-moving space/unevac from space ref " << obj << " " << PrettyTypeOf(obj) 578 << " has non-black rb_ptr " << obj->GetReadBarrierPointer() 579 << " but isn't on the alloc stack (and has white rb_ptr). Is it in the non-moving space=" 580 << (collector->GetHeap()->GetNonMovingSpace()->HasAddress(obj)); 581 } 582 } 583 } 584 585 private: 586 ConcurrentCopying* const collector_; 587 }; 588 589 // Verify there's no from-space references left after the marking phase. 590 void ConcurrentCopying::VerifyNoFromSpaceReferences() { 591 Thread* self = Thread::Current(); 592 DCHECK(Locks::mutator_lock_->IsExclusiveHeld(self)); 593 ConcurrentCopyingVerifyNoFromSpaceRefsObjectVisitor visitor(this); 594 // Roots. 595 { 596 ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_); 597 ConcurrentCopyingVerifyNoFromSpaceRefsVisitor ref_visitor(this); 598 Runtime::Current()->VisitRoots(&ref_visitor); 599 } 600 // The to-space. 601 region_space_->WalkToSpace(ConcurrentCopyingVerifyNoFromSpaceRefsObjectVisitor::ObjectCallback, 602 this); 603 // Non-moving spaces. 604 { 605 WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); 606 heap_->GetMarkBitmap()->Visit(visitor); 607 } 608 // The alloc stack. 609 { 610 ConcurrentCopyingVerifyNoFromSpaceRefsVisitor ref_visitor(this); 611 for (auto* it = heap_->allocation_stack_->Begin(), *end = heap_->allocation_stack_->End(); 612 it < end; ++it) { 613 mirror::Object* const obj = it->AsMirrorPtr(); 614 if (obj != nullptr && obj->GetClass() != nullptr) { 615 // TODO: need to call this only if obj is alive? 616 ref_visitor(obj); 617 visitor(obj); 618 } 619 } 620 } 621 // TODO: LOS. But only refs in LOS are classes. 622 } 623 624 // The following visitors are used to assert the to-space invariant. 625 class ConcurrentCopyingAssertToSpaceInvariantRefsVisitor { 626 public: 627 explicit ConcurrentCopyingAssertToSpaceInvariantRefsVisitor(ConcurrentCopying* collector) 628 : collector_(collector) {} 629 630 void operator()(mirror::Object* ref) const 631 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 632 if (ref == nullptr) { 633 // OK. 634 return; 635 } 636 collector_->AssertToSpaceInvariant(nullptr, MemberOffset(0), ref); 637 } 638 static void RootCallback(mirror::Object** root, void *arg, const RootInfo& /*root_info*/) 639 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 640 ConcurrentCopying* collector = reinterpret_cast<ConcurrentCopying*>(arg); 641 ConcurrentCopyingAssertToSpaceInvariantRefsVisitor visitor(collector); 642 DCHECK(root != nullptr); 643 visitor(*root); 644 } 645 646 private: 647 ConcurrentCopying* collector_; 648 }; 649 650 class ConcurrentCopyingAssertToSpaceInvariantFieldVisitor { 651 public: 652 explicit ConcurrentCopyingAssertToSpaceInvariantFieldVisitor(ConcurrentCopying* collector) 653 : collector_(collector) {} 654 655 void operator()(mirror::Object* obj, MemberOffset offset, bool /* is_static */) const 656 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 657 mirror::Object* ref = 658 obj->GetFieldObject<mirror::Object, kDefaultVerifyFlags, kWithoutReadBarrier>(offset); 659 ConcurrentCopyingAssertToSpaceInvariantRefsVisitor visitor(collector_); 660 visitor(ref); 661 } 662 void operator()(mirror::Class* klass, mirror::Reference* /* ref */) const 663 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 664 CHECK(klass->IsTypeOfReferenceClass()); 665 } 666 667 private: 668 ConcurrentCopying* collector_; 669 }; 670 671 class ConcurrentCopyingAssertToSpaceInvariantObjectVisitor { 672 public: 673 explicit ConcurrentCopyingAssertToSpaceInvariantObjectVisitor(ConcurrentCopying* collector) 674 : collector_(collector) {} 675 void operator()(mirror::Object* obj) const 676 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 677 ObjectCallback(obj, collector_); 678 } 679 static void ObjectCallback(mirror::Object* obj, void *arg) 680 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { 681 CHECK(obj != nullptr); 682 ConcurrentCopying* collector = reinterpret_cast<ConcurrentCopying*>(arg); 683 space::RegionSpace* region_space = collector->RegionSpace(); 684 CHECK(!region_space->IsInFromSpace(obj)) << "Scanning object " << obj << " in from space"; 685 collector->AssertToSpaceInvariant(nullptr, MemberOffset(0), obj); 686 ConcurrentCopyingAssertToSpaceInvariantFieldVisitor visitor(collector); 687 obj->VisitReferences<true>(visitor, visitor); 688 } 689 690 private: 691 ConcurrentCopying* collector_; 692 }; 693 694 bool ConcurrentCopying::ProcessMarkStack() { 695 if (kVerboseMode) { 696 LOG(INFO) << "ProcessMarkStack. "; 697 } 698 size_t count = 0; 699 mirror::Object* to_ref; 700 while ((to_ref = PopOffMarkStack()) != nullptr) { 701 ++count; 702 DCHECK(!region_space_->IsInFromSpace(to_ref)); 703 if (kUseBakerReadBarrier) { 704 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()) 705 << " " << to_ref << " " << to_ref->GetReadBarrierPointer() 706 << " is_marked=" << IsMarked(to_ref); 707 } 708 // Scan ref fields. 709 Scan(to_ref); 710 // Mark the gray ref as white or black. 711 if (kUseBakerReadBarrier) { 712 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()) 713 << " " << to_ref << " " << to_ref->GetReadBarrierPointer() 714 << " is_marked=" << IsMarked(to_ref); 715 } 716 if (to_ref->GetClass<kVerifyNone, kWithoutReadBarrier>()->IsTypeOfReferenceClass() && 717 to_ref->AsReference()->GetReferent<kWithoutReadBarrier>() != nullptr && 718 !IsInToSpace(to_ref->AsReference()->GetReferent<kWithoutReadBarrier>())) { 719 // Leave References gray so that GetReferent() will trigger RB. 720 CHECK(to_ref->AsReference()->IsEnqueued()) << "Left unenqueued ref gray " << to_ref; 721 } else { 722 #ifdef USE_BAKER_OR_BROOKS_READ_BARRIER 723 if (kUseBakerReadBarrier) { 724 if (region_space_->IsInToSpace(to_ref)) { 725 // If to-space, change from gray to white. 726 bool success = to_ref->AtomicSetReadBarrierPointer(ReadBarrier::GrayPtr(), 727 ReadBarrier::WhitePtr()); 728 CHECK(success) << "Must succeed as we won the race."; 729 CHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::WhitePtr()); 730 } else { 731 // If non-moving space/unevac from space, change from gray 732 // to black. We can't change gray to white because it's not 733 // safe to use CAS if two threads change values in opposite 734 // directions (A->B and B->A). So, we change it to black to 735 // indicate non-moving objects that have been marked 736 // through. Note we'd need to change from black to white 737 // later (concurrently). 738 bool success = to_ref->AtomicSetReadBarrierPointer(ReadBarrier::GrayPtr(), 739 ReadBarrier::BlackPtr()); 740 CHECK(success) << "Must succeed as we won the race."; 741 CHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::BlackPtr()); 742 } 743 } 744 #else 745 DCHECK(!kUseBakerReadBarrier); 746 #endif 747 } 748 if (ReadBarrier::kEnableToSpaceInvariantChecks || kIsDebugBuild) { 749 ConcurrentCopyingAssertToSpaceInvariantObjectVisitor visitor(this); 750 visitor(to_ref); 751 } 752 } 753 // Return true if the stack was empty. 754 return count == 0; 755 } 756 757 void ConcurrentCopying::CheckEmptyMarkQueue() { 758 if (!mark_queue_.IsEmpty()) { 759 while (!mark_queue_.IsEmpty()) { 760 mirror::Object* obj = mark_queue_.Dequeue(); 761 if (kUseBakerReadBarrier) { 762 mirror::Object* rb_ptr = obj->GetReadBarrierPointer(); 763 LOG(INFO) << "On mark queue : " << obj << " " << PrettyTypeOf(obj) << " rb_ptr=" << rb_ptr 764 << " is_marked=" << IsMarked(obj); 765 } else { 766 LOG(INFO) << "On mark queue : " << obj << " " << PrettyTypeOf(obj) 767 << " is_marked=" << IsMarked(obj); 768 } 769 } 770 LOG(FATAL) << "mark queue is not empty"; 771 } 772 } 773 774 void ConcurrentCopying::SweepSystemWeaks(Thread* self) { 775 TimingLogger::ScopedTiming split("SweepSystemWeaks", GetTimings()); 776 ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_); 777 Runtime::Current()->SweepSystemWeaks(IsMarkedCallback, this); 778 } 779 780 void ConcurrentCopying::Sweep(bool swap_bitmaps) { 781 { 782 TimingLogger::ScopedTiming t("MarkStackAsLive", GetTimings()); 783 accounting::ObjectStack* live_stack = heap_->GetLiveStack(); 784 if (kEnableFromSpaceAccountingCheck) { 785 CHECK_GE(live_stack_freeze_size_, live_stack->Size()); 786 } 787 heap_->MarkAllocStackAsLive(live_stack); 788 live_stack->Reset(); 789 } 790 CHECK(mark_queue_.IsEmpty()); 791 TimingLogger::ScopedTiming split("Sweep", GetTimings()); 792 for (const auto& space : GetHeap()->GetContinuousSpaces()) { 793 if (space->IsContinuousMemMapAllocSpace()) { 794 space::ContinuousMemMapAllocSpace* alloc_space = space->AsContinuousMemMapAllocSpace(); 795 if (space == region_space_ || immune_region_.ContainsSpace(space)) { 796 continue; 797 } 798 TimingLogger::ScopedTiming split2( 799 alloc_space->IsZygoteSpace() ? "SweepZygoteSpace" : "SweepAllocSpace", GetTimings()); 800 RecordFree(alloc_space->Sweep(swap_bitmaps)); 801 } 802 } 803 SweepLargeObjects(swap_bitmaps); 804 } 805 806 void ConcurrentCopying::SweepLargeObjects(bool swap_bitmaps) { 807 TimingLogger::ScopedTiming split("SweepLargeObjects", GetTimings()); 808 RecordFreeLOS(heap_->GetLargeObjectsSpace()->Sweep(swap_bitmaps)); 809 } 810 811 class ConcurrentCopyingClearBlackPtrsVisitor { 812 public: 813 explicit ConcurrentCopyingClearBlackPtrsVisitor(ConcurrentCopying* cc) 814 : collector_(cc) {} 815 #ifndef USE_BAKER_OR_BROOKS_READ_BARRIER 816 NO_RETURN 817 #endif 818 void operator()(mirror::Object* obj) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 819 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) { 820 DCHECK(obj != nullptr); 821 DCHECK(collector_->heap_->GetMarkBitmap()->Test(obj)) << obj; 822 DCHECK_EQ(obj->GetReadBarrierPointer(), ReadBarrier::BlackPtr()) << obj; 823 obj->AtomicSetReadBarrierPointer(ReadBarrier::BlackPtr(), ReadBarrier::WhitePtr()); 824 DCHECK_EQ(obj->GetReadBarrierPointer(), ReadBarrier::WhitePtr()) << obj; 825 } 826 827 private: 828 ConcurrentCopying* const collector_; 829 }; 830 831 // Clear the black ptrs in non-moving objects back to white. 832 void ConcurrentCopying::ClearBlackPtrs() { 833 CHECK(kUseBakerReadBarrier); 834 TimingLogger::ScopedTiming split("ClearBlackPtrs", GetTimings()); 835 ConcurrentCopyingClearBlackPtrsVisitor visitor(this); 836 for (auto& space : heap_->GetContinuousSpaces()) { 837 if (space == region_space_) { 838 continue; 839 } 840 accounting::ContinuousSpaceBitmap* mark_bitmap = space->GetMarkBitmap(); 841 if (kVerboseMode) { 842 LOG(INFO) << "ClearBlackPtrs: " << *space << " bitmap: " << *mark_bitmap; 843 } 844 mark_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()), 845 reinterpret_cast<uintptr_t>(space->Limit()), 846 visitor); 847 } 848 space::LargeObjectSpace* large_object_space = heap_->GetLargeObjectsSpace(); 849 large_object_space->GetMarkBitmap()->VisitMarkedRange( 850 reinterpret_cast<uintptr_t>(large_object_space->Begin()), 851 reinterpret_cast<uintptr_t>(large_object_space->End()), 852 visitor); 853 // Objects on the allocation stack? 854 if (ReadBarrier::kEnableReadBarrierInvariantChecks || kIsDebugBuild) { 855 size_t count = GetAllocationStack()->Size(); 856 auto* it = GetAllocationStack()->Begin(); 857 auto* end = GetAllocationStack()->End(); 858 for (size_t i = 0; i < count; ++i, ++it) { 859 CHECK_LT(it, end); 860 mirror::Object* obj = it->AsMirrorPtr(); 861 if (obj != nullptr) { 862 // Must have been cleared above. 863 CHECK_EQ(obj->GetReadBarrierPointer(), ReadBarrier::WhitePtr()) << obj; 864 } 865 } 866 } 867 } 868 869 void ConcurrentCopying::ReclaimPhase() { 870 TimingLogger::ScopedTiming split("ReclaimPhase", GetTimings()); 871 if (kVerboseMode) { 872 LOG(INFO) << "GC ReclaimPhase"; 873 } 874 Thread* self = Thread::Current(); 875 876 { 877 // Double-check that the mark stack is empty. 878 // Note: need to set this after VerifyNoFromSpaceRef(). 879 is_asserting_to_space_invariant_ = false; 880 QuasiAtomic::ThreadFenceForConstructor(); 881 if (kVerboseMode) { 882 LOG(INFO) << "Issue an empty check point. "; 883 } 884 IssueEmptyCheckpoint(); 885 // Disable the check. 886 is_mark_queue_push_disallowed_.StoreSequentiallyConsistent(0); 887 CheckEmptyMarkQueue(); 888 } 889 890 { 891 // Record freed objects. 892 TimingLogger::ScopedTiming split2("RecordFree", GetTimings()); 893 // Don't include thread-locals that are in the to-space. 894 uint64_t from_bytes = region_space_->GetBytesAllocatedInFromSpace(); 895 uint64_t from_objects = region_space_->GetObjectsAllocatedInFromSpace(); 896 uint64_t unevac_from_bytes = region_space_->GetBytesAllocatedInUnevacFromSpace(); 897 uint64_t unevac_from_objects = region_space_->GetObjectsAllocatedInUnevacFromSpace(); 898 uint64_t to_bytes = bytes_moved_.LoadSequentiallyConsistent(); 899 uint64_t to_objects = objects_moved_.LoadSequentiallyConsistent(); 900 if (kEnableFromSpaceAccountingCheck) { 901 CHECK_EQ(from_space_num_objects_at_first_pause_, from_objects + unevac_from_objects); 902 CHECK_EQ(from_space_num_bytes_at_first_pause_, from_bytes + unevac_from_bytes); 903 } 904 CHECK_LE(to_objects, from_objects); 905 CHECK_LE(to_bytes, from_bytes); 906 int64_t freed_bytes = from_bytes - to_bytes; 907 int64_t freed_objects = from_objects - to_objects; 908 if (kVerboseMode) { 909 LOG(INFO) << "RecordFree:" 910 << " from_bytes=" << from_bytes << " from_objects=" << from_objects 911 << " unevac_from_bytes=" << unevac_from_bytes << " unevac_from_objects=" << unevac_from_objects 912 << " to_bytes=" << to_bytes << " to_objects=" << to_objects 913 << " freed_bytes=" << freed_bytes << " freed_objects=" << freed_objects 914 << " from_space size=" << region_space_->FromSpaceSize() 915 << " unevac_from_space size=" << region_space_->UnevacFromSpaceSize() 916 << " to_space size=" << region_space_->ToSpaceSize(); 917 LOG(INFO) << "(before) num_bytes_allocated=" << heap_->num_bytes_allocated_.LoadSequentiallyConsistent(); 918 } 919 RecordFree(ObjectBytePair(freed_objects, freed_bytes)); 920 if (kVerboseMode) { 921 LOG(INFO) << "(after) num_bytes_allocated=" << heap_->num_bytes_allocated_.LoadSequentiallyConsistent(); 922 } 923 } 924 925 { 926 TimingLogger::ScopedTiming split3("ComputeUnevacFromSpaceLiveRatio", GetTimings()); 927 ComputeUnevacFromSpaceLiveRatio(); 928 } 929 930 { 931 TimingLogger::ScopedTiming split4("ClearFromSpace", GetTimings()); 932 region_space_->ClearFromSpace(); 933 } 934 935 { 936 WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); 937 if (kUseBakerReadBarrier) { 938 ClearBlackPtrs(); 939 } 940 Sweep(false); 941 SwapBitmaps(); 942 heap_->UnBindBitmaps(); 943 944 // Remove bitmaps for the immune spaces. 945 while (!cc_bitmaps_.empty()) { 946 accounting::ContinuousSpaceBitmap* cc_bitmap = cc_bitmaps_.back(); 947 cc_heap_bitmap_->RemoveContinuousSpaceBitmap(cc_bitmap); 948 delete cc_bitmap; 949 cc_bitmaps_.pop_back(); 950 } 951 region_space_bitmap_ = nullptr; 952 } 953 954 if (kVerboseMode) { 955 LOG(INFO) << "GC end of ReclaimPhase"; 956 } 957 } 958 959 class ConcurrentCopyingComputeUnevacFromSpaceLiveRatioVisitor { 960 public: 961 explicit ConcurrentCopyingComputeUnevacFromSpaceLiveRatioVisitor(ConcurrentCopying* cc) 962 : collector_(cc) {} 963 void operator()(mirror::Object* ref) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 964 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) { 965 DCHECK(ref != nullptr); 966 DCHECK(collector_->region_space_bitmap_->Test(ref)) << ref; 967 DCHECK(collector_->region_space_->IsInUnevacFromSpace(ref)) << ref; 968 if (kUseBakerReadBarrier) { 969 DCHECK_EQ(ref->GetReadBarrierPointer(), ReadBarrier::BlackPtr()) << ref; 970 // Clear the black ptr. 971 ref->AtomicSetReadBarrierPointer(ReadBarrier::BlackPtr(), ReadBarrier::WhitePtr()); 972 DCHECK_EQ(ref->GetReadBarrierPointer(), ReadBarrier::WhitePtr()) << ref; 973 } 974 size_t obj_size = ref->SizeOf(); 975 size_t alloc_size = RoundUp(obj_size, space::RegionSpace::kAlignment); 976 collector_->region_space_->AddLiveBytes(ref, alloc_size); 977 } 978 979 private: 980 ConcurrentCopying* collector_; 981 }; 982 983 // Compute how much live objects are left in regions. 984 void ConcurrentCopying::ComputeUnevacFromSpaceLiveRatio() { 985 region_space_->AssertAllRegionLiveBytesZeroOrCleared(); 986 ConcurrentCopyingComputeUnevacFromSpaceLiveRatioVisitor visitor(this); 987 region_space_bitmap_->VisitMarkedRange(reinterpret_cast<uintptr_t>(region_space_->Begin()), 988 reinterpret_cast<uintptr_t>(region_space_->Limit()), 989 visitor); 990 } 991 992 // Assert the to-space invariant. 993 void ConcurrentCopying::AssertToSpaceInvariant(mirror::Object* obj, MemberOffset offset, 994 mirror::Object* ref) { 995 CHECK(heap_->collector_type_ == kCollectorTypeCC) << static_cast<size_t>(heap_->collector_type_); 996 if (is_asserting_to_space_invariant_) { 997 if (region_space_->IsInToSpace(ref)) { 998 // OK. 999 return; 1000 } else if (region_space_->IsInUnevacFromSpace(ref)) { 1001 CHECK(region_space_bitmap_->Test(ref)) << ref; 1002 } else if (region_space_->IsInFromSpace(ref)) { 1003 // Not OK. Do extra logging. 1004 if (obj != nullptr) { 1005 if (kUseBakerReadBarrier) { 1006 LOG(INFO) << "holder=" << obj << " " << PrettyTypeOf(obj) 1007 << " holder rb_ptr=" << obj->GetReadBarrierPointer(); 1008 } else { 1009 LOG(INFO) << "holder=" << obj << " " << PrettyTypeOf(obj); 1010 } 1011 if (region_space_->IsInFromSpace(obj)) { 1012 LOG(INFO) << "holder is in the from-space."; 1013 } else if (region_space_->IsInToSpace(obj)) { 1014 LOG(INFO) << "holder is in the to-space."; 1015 } else if (region_space_->IsInUnevacFromSpace(obj)) { 1016 LOG(INFO) << "holder is in the unevac from-space."; 1017 if (region_space_bitmap_->Test(obj)) { 1018 LOG(INFO) << "holder is marked in the region space bitmap."; 1019 } else { 1020 LOG(INFO) << "holder is not marked in the region space bitmap."; 1021 } 1022 } else { 1023 // In a non-moving space. 1024 if (immune_region_.ContainsObject(obj)) { 1025 LOG(INFO) << "holder is in the image or the zygote space."; 1026 accounting::ContinuousSpaceBitmap* cc_bitmap = 1027 cc_heap_bitmap_->GetContinuousSpaceBitmap(obj); 1028 CHECK(cc_bitmap != nullptr) 1029 << "An immune space object must have a bitmap."; 1030 if (cc_bitmap->Test(obj)) { 1031 LOG(INFO) << "holder is marked in the bit map."; 1032 } else { 1033 LOG(INFO) << "holder is NOT marked in the bit map."; 1034 } 1035 } else { 1036 LOG(INFO) << "holder is in a non-moving (or main) space."; 1037 accounting::ContinuousSpaceBitmap* mark_bitmap = 1038 heap_mark_bitmap_->GetContinuousSpaceBitmap(obj); 1039 accounting::LargeObjectBitmap* los_bitmap = 1040 heap_mark_bitmap_->GetLargeObjectBitmap(obj); 1041 CHECK(los_bitmap != nullptr) << "LOS bitmap covers the entire address range"; 1042 bool is_los = mark_bitmap == nullptr; 1043 if (!is_los && mark_bitmap->Test(obj)) { 1044 LOG(INFO) << "holder is marked in the mark bit map."; 1045 } else if (is_los && los_bitmap->Test(obj)) { 1046 LOG(INFO) << "holder is marked in the los bit map."; 1047 } else { 1048 // If ref is on the allocation stack, then it is considered 1049 // mark/alive (but not necessarily on the live stack.) 1050 if (IsOnAllocStack(obj)) { 1051 LOG(INFO) << "holder is on the alloc stack."; 1052 } else { 1053 LOG(INFO) << "holder is not marked or on the alloc stack."; 1054 } 1055 } 1056 } 1057 } 1058 LOG(INFO) << "offset=" << offset.SizeValue(); 1059 } 1060 CHECK(false) << "Found from-space ref " << ref << " " << PrettyTypeOf(ref); 1061 } else { 1062 // In a non-moving spaces. Check that the ref is marked. 1063 if (immune_region_.ContainsObject(ref)) { 1064 accounting::ContinuousSpaceBitmap* cc_bitmap = 1065 cc_heap_bitmap_->GetContinuousSpaceBitmap(ref); 1066 CHECK(cc_bitmap != nullptr) 1067 << "An immune space ref must have a bitmap. " << ref; 1068 if (kUseBakerReadBarrier) { 1069 CHECK(cc_bitmap->Test(ref)) 1070 << "Unmarked immune space ref. obj=" << obj << " rb_ptr=" 1071 << obj->GetReadBarrierPointer() << " ref=" << ref; 1072 } else { 1073 CHECK(cc_bitmap->Test(ref)) 1074 << "Unmarked immune space ref. obj=" << obj << " ref=" << ref; 1075 } 1076 } else { 1077 accounting::ContinuousSpaceBitmap* mark_bitmap = 1078 heap_mark_bitmap_->GetContinuousSpaceBitmap(ref); 1079 accounting::LargeObjectBitmap* los_bitmap = 1080 heap_mark_bitmap_->GetLargeObjectBitmap(ref); 1081 CHECK(los_bitmap != nullptr) << "LOS bitmap covers the entire address range"; 1082 bool is_los = mark_bitmap == nullptr; 1083 if ((!is_los && mark_bitmap->Test(ref)) || 1084 (is_los && los_bitmap->Test(ref))) { 1085 // OK. 1086 } else { 1087 // If ref is on the allocation stack, then it may not be 1088 // marked live, but considered marked/alive (but not 1089 // necessarily on the live stack). 1090 CHECK(IsOnAllocStack(ref)) << "Unmarked ref that's not on the allocation stack. " 1091 << "obj=" << obj << " ref=" << ref; 1092 } 1093 } 1094 } 1095 } 1096 } 1097 1098 // Used to scan ref fields of an object. 1099 class ConcurrentCopyingRefFieldsVisitor { 1100 public: 1101 explicit ConcurrentCopyingRefFieldsVisitor(ConcurrentCopying* collector) 1102 : collector_(collector) {} 1103 1104 void operator()(mirror::Object* obj, MemberOffset offset, bool /* is_static */) 1105 const ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 1106 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) { 1107 collector_->Process(obj, offset); 1108 } 1109 1110 void operator()(mirror::Class* klass, mirror::Reference* ref) const 1111 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE { 1112 CHECK(klass->IsTypeOfReferenceClass()); 1113 collector_->DelayReferenceReferent(klass, ref); 1114 } 1115 1116 private: 1117 ConcurrentCopying* const collector_; 1118 }; 1119 1120 // Scan ref fields of an object. 1121 void ConcurrentCopying::Scan(mirror::Object* to_ref) { 1122 DCHECK(!region_space_->IsInFromSpace(to_ref)); 1123 ConcurrentCopyingRefFieldsVisitor visitor(this); 1124 to_ref->VisitReferences<true>(visitor, visitor); 1125 } 1126 1127 // Process a field. 1128 inline void ConcurrentCopying::Process(mirror::Object* obj, MemberOffset offset) { 1129 mirror::Object* ref = obj->GetFieldObject<mirror::Object, kVerifyNone, kWithoutReadBarrier, false>(offset); 1130 if (ref == nullptr || region_space_->IsInToSpace(ref)) { 1131 return; 1132 } 1133 mirror::Object* to_ref = Mark(ref); 1134 if (to_ref == ref) { 1135 return; 1136 } 1137 // This may fail if the mutator writes to the field at the same time. But it's ok. 1138 mirror::Object* expected_ref = ref; 1139 mirror::Object* new_ref = to_ref; 1140 do { 1141 if (expected_ref != 1142 obj->GetFieldObject<mirror::Object, kVerifyNone, kWithoutReadBarrier, false>(offset)) { 1143 // It was updated by the mutator. 1144 break; 1145 } 1146 } while (!obj->CasFieldWeakSequentiallyConsistentObjectWithoutWriteBarrier<false, false, kVerifyNone>( 1147 offset, expected_ref, new_ref)); 1148 } 1149 1150 // Process some roots. 1151 void ConcurrentCopying::VisitRoots( 1152 mirror::Object*** roots, size_t count, const RootInfo& info ATTRIBUTE_UNUSED) { 1153 for (size_t i = 0; i < count; ++i) { 1154 mirror::Object** root = roots[i]; 1155 mirror::Object* ref = *root; 1156 if (ref == nullptr || region_space_->IsInToSpace(ref)) { 1157 continue; 1158 } 1159 mirror::Object* to_ref = Mark(ref); 1160 if (to_ref == ref) { 1161 continue; 1162 } 1163 Atomic<mirror::Object*>* addr = reinterpret_cast<Atomic<mirror::Object*>*>(root); 1164 mirror::Object* expected_ref = ref; 1165 mirror::Object* new_ref = to_ref; 1166 do { 1167 if (expected_ref != addr->LoadRelaxed()) { 1168 // It was updated by the mutator. 1169 break; 1170 } 1171 } while (!addr->CompareExchangeWeakSequentiallyConsistent(expected_ref, new_ref)); 1172 } 1173 } 1174 1175 void ConcurrentCopying::VisitRoots( 1176 mirror::CompressedReference<mirror::Object>** roots, size_t count, 1177 const RootInfo& info ATTRIBUTE_UNUSED) { 1178 for (size_t i = 0; i < count; ++i) { 1179 mirror::CompressedReference<mirror::Object>* root = roots[i]; 1180 mirror::Object* ref = root->AsMirrorPtr(); 1181 if (ref == nullptr || region_space_->IsInToSpace(ref)) { 1182 continue; 1183 } 1184 mirror::Object* to_ref = Mark(ref); 1185 if (to_ref == ref) { 1186 continue; 1187 } 1188 auto* addr = reinterpret_cast<Atomic<mirror::CompressedReference<mirror::Object>>*>(root); 1189 auto expected_ref = mirror::CompressedReference<mirror::Object>::FromMirrorPtr(ref); 1190 auto new_ref = mirror::CompressedReference<mirror::Object>::FromMirrorPtr(to_ref); 1191 do { 1192 if (ref != addr->LoadRelaxed().AsMirrorPtr()) { 1193 // It was updated by the mutator. 1194 break; 1195 } 1196 } while (!addr->CompareExchangeWeakSequentiallyConsistent(expected_ref, new_ref)); 1197 } 1198 } 1199 1200 // Fill the given memory block with a dummy object. Used to fill in a 1201 // copy of objects that was lost in race. 1202 void ConcurrentCopying::FillWithDummyObject(mirror::Object* dummy_obj, size_t byte_size) { 1203 CHECK(IsAligned<kObjectAlignment>(byte_size)); 1204 memset(dummy_obj, 0, byte_size); 1205 mirror::Class* int_array_class = mirror::IntArray::GetArrayClass(); 1206 CHECK(int_array_class != nullptr); 1207 AssertToSpaceInvariant(nullptr, MemberOffset(0), int_array_class); 1208 size_t component_size = int_array_class->GetComponentSize(); 1209 CHECK_EQ(component_size, sizeof(int32_t)); 1210 size_t data_offset = mirror::Array::DataOffset(component_size).SizeValue(); 1211 if (data_offset > byte_size) { 1212 // An int array is too big. Use java.lang.Object. 1213 mirror::Class* java_lang_Object = WellKnownClasses::ToClass(WellKnownClasses::java_lang_Object); 1214 AssertToSpaceInvariant(nullptr, MemberOffset(0), java_lang_Object); 1215 CHECK_EQ(byte_size, java_lang_Object->GetObjectSize()); 1216 dummy_obj->SetClass(java_lang_Object); 1217 CHECK_EQ(byte_size, dummy_obj->SizeOf()); 1218 } else { 1219 // Use an int array. 1220 dummy_obj->SetClass(int_array_class); 1221 CHECK(dummy_obj->IsArrayInstance()); 1222 int32_t length = (byte_size - data_offset) / component_size; 1223 dummy_obj->AsArray()->SetLength(length); 1224 CHECK_EQ(dummy_obj->AsArray()->GetLength(), length) 1225 << "byte_size=" << byte_size << " length=" << length 1226 << " component_size=" << component_size << " data_offset=" << data_offset; 1227 CHECK_EQ(byte_size, dummy_obj->SizeOf()) 1228 << "byte_size=" << byte_size << " length=" << length 1229 << " component_size=" << component_size << " data_offset=" << data_offset; 1230 } 1231 } 1232 1233 // Reuse the memory blocks that were copy of objects that were lost in race. 1234 mirror::Object* ConcurrentCopying::AllocateInSkippedBlock(size_t alloc_size) { 1235 // Try to reuse the blocks that were unused due to CAS failures. 1236 CHECK(IsAligned<space::RegionSpace::kAlignment>(alloc_size)); 1237 Thread* self = Thread::Current(); 1238 size_t min_object_size = RoundUp(sizeof(mirror::Object), space::RegionSpace::kAlignment); 1239 MutexLock mu(self, skipped_blocks_lock_); 1240 auto it = skipped_blocks_map_.lower_bound(alloc_size); 1241 if (it == skipped_blocks_map_.end()) { 1242 // Not found. 1243 return nullptr; 1244 } 1245 { 1246 size_t byte_size = it->first; 1247 CHECK_GE(byte_size, alloc_size); 1248 if (byte_size > alloc_size && byte_size - alloc_size < min_object_size) { 1249 // If remainder would be too small for a dummy object, retry with a larger request size. 1250 it = skipped_blocks_map_.lower_bound(alloc_size + min_object_size); 1251 if (it == skipped_blocks_map_.end()) { 1252 // Not found. 1253 return nullptr; 1254 } 1255 CHECK(IsAligned<space::RegionSpace::kAlignment>(it->first - alloc_size)); 1256 CHECK_GE(it->first - alloc_size, min_object_size) 1257 << "byte_size=" << byte_size << " it->first=" << it->first << " alloc_size=" << alloc_size; 1258 } 1259 } 1260 // Found a block. 1261 CHECK(it != skipped_blocks_map_.end()); 1262 size_t byte_size = it->first; 1263 uint8_t* addr = it->second; 1264 CHECK_GE(byte_size, alloc_size); 1265 CHECK(region_space_->IsInToSpace(reinterpret_cast<mirror::Object*>(addr))); 1266 CHECK(IsAligned<space::RegionSpace::kAlignment>(byte_size)); 1267 if (kVerboseMode) { 1268 LOG(INFO) << "Reusing skipped bytes : " << reinterpret_cast<void*>(addr) << ", " << byte_size; 1269 } 1270 skipped_blocks_map_.erase(it); 1271 memset(addr, 0, byte_size); 1272 if (byte_size > alloc_size) { 1273 // Return the remainder to the map. 1274 CHECK(IsAligned<space::RegionSpace::kAlignment>(byte_size - alloc_size)); 1275 CHECK_GE(byte_size - alloc_size, min_object_size); 1276 FillWithDummyObject(reinterpret_cast<mirror::Object*>(addr + alloc_size), 1277 byte_size - alloc_size); 1278 CHECK(region_space_->IsInToSpace(reinterpret_cast<mirror::Object*>(addr + alloc_size))); 1279 skipped_blocks_map_.insert(std::make_pair(byte_size - alloc_size, addr + alloc_size)); 1280 } 1281 return reinterpret_cast<mirror::Object*>(addr); 1282 } 1283 1284 mirror::Object* ConcurrentCopying::Copy(mirror::Object* from_ref) { 1285 DCHECK(region_space_->IsInFromSpace(from_ref)); 1286 // No read barrier to avoid nested RB that might violate the to-space 1287 // invariant. Note that from_ref is a from space ref so the SizeOf() 1288 // call will access the from-space meta objects, but it's ok and necessary. 1289 size_t obj_size = from_ref->SizeOf<kDefaultVerifyFlags, kWithoutReadBarrier>(); 1290 size_t region_space_alloc_size = RoundUp(obj_size, space::RegionSpace::kAlignment); 1291 size_t region_space_bytes_allocated = 0U; 1292 size_t non_moving_space_bytes_allocated = 0U; 1293 size_t bytes_allocated = 0U; 1294 size_t dummy; 1295 mirror::Object* to_ref = region_space_->AllocNonvirtual<true>( 1296 region_space_alloc_size, ®ion_space_bytes_allocated, nullptr, &dummy); 1297 bytes_allocated = region_space_bytes_allocated; 1298 if (to_ref != nullptr) { 1299 DCHECK_EQ(region_space_alloc_size, region_space_bytes_allocated); 1300 } 1301 bool fall_back_to_non_moving = false; 1302 if (UNLIKELY(to_ref == nullptr)) { 1303 // Failed to allocate in the region space. Try the skipped blocks. 1304 to_ref = AllocateInSkippedBlock(region_space_alloc_size); 1305 if (to_ref != nullptr) { 1306 // Succeeded to allocate in a skipped block. 1307 if (heap_->use_tlab_) { 1308 // This is necessary for the tlab case as it's not accounted in the space. 1309 region_space_->RecordAlloc(to_ref); 1310 } 1311 bytes_allocated = region_space_alloc_size; 1312 } else { 1313 // Fall back to the non-moving space. 1314 fall_back_to_non_moving = true; 1315 if (kVerboseMode) { 1316 LOG(INFO) << "Out of memory in the to-space. Fall back to non-moving. skipped_bytes=" 1317 << to_space_bytes_skipped_.LoadSequentiallyConsistent() 1318 << " skipped_objects=" << to_space_objects_skipped_.LoadSequentiallyConsistent(); 1319 } 1320 fall_back_to_non_moving = true; 1321 to_ref = heap_->non_moving_space_->Alloc(Thread::Current(), obj_size, 1322 &non_moving_space_bytes_allocated, nullptr, &dummy); 1323 CHECK(to_ref != nullptr) << "Fall-back non-moving space allocation failed"; 1324 bytes_allocated = non_moving_space_bytes_allocated; 1325 // Mark it in the mark bitmap. 1326 accounting::ContinuousSpaceBitmap* mark_bitmap = 1327 heap_mark_bitmap_->GetContinuousSpaceBitmap(to_ref); 1328 CHECK(mark_bitmap != nullptr); 1329 CHECK(!mark_bitmap->AtomicTestAndSet(to_ref)); 1330 } 1331 } 1332 DCHECK(to_ref != nullptr); 1333 1334 // Attempt to install the forward pointer. This is in a loop as the 1335 // lock word atomic write can fail. 1336 while (true) { 1337 // Copy the object. TODO: copy only the lockword in the second iteration and on? 1338 memcpy(to_ref, from_ref, obj_size); 1339 1340 LockWord old_lock_word = to_ref->GetLockWord(false); 1341 1342 if (old_lock_word.GetState() == LockWord::kForwardingAddress) { 1343 // Lost the race. Another thread (either GC or mutator) stored 1344 // the forwarding pointer first. Make the lost copy (to_ref) 1345 // look like a valid but dead (dummy) object and keep it for 1346 // future reuse. 1347 FillWithDummyObject(to_ref, bytes_allocated); 1348 if (!fall_back_to_non_moving) { 1349 DCHECK(region_space_->IsInToSpace(to_ref)); 1350 if (bytes_allocated > space::RegionSpace::kRegionSize) { 1351 // Free the large alloc. 1352 region_space_->FreeLarge(to_ref, bytes_allocated); 1353 } else { 1354 // Record the lost copy for later reuse. 1355 heap_->num_bytes_allocated_.FetchAndAddSequentiallyConsistent(bytes_allocated); 1356 to_space_bytes_skipped_.FetchAndAddSequentiallyConsistent(bytes_allocated); 1357 to_space_objects_skipped_.FetchAndAddSequentiallyConsistent(1); 1358 MutexLock mu(Thread::Current(), skipped_blocks_lock_); 1359 skipped_blocks_map_.insert(std::make_pair(bytes_allocated, 1360 reinterpret_cast<uint8_t*>(to_ref))); 1361 } 1362 } else { 1363 DCHECK(heap_->non_moving_space_->HasAddress(to_ref)); 1364 DCHECK_EQ(bytes_allocated, non_moving_space_bytes_allocated); 1365 // Free the non-moving-space chunk. 1366 accounting::ContinuousSpaceBitmap* mark_bitmap = 1367 heap_mark_bitmap_->GetContinuousSpaceBitmap(to_ref); 1368 CHECK(mark_bitmap != nullptr); 1369 CHECK(mark_bitmap->Clear(to_ref)); 1370 heap_->non_moving_space_->Free(Thread::Current(), to_ref); 1371 } 1372 1373 // Get the winner's forward ptr. 1374 mirror::Object* lost_fwd_ptr = to_ref; 1375 to_ref = reinterpret_cast<mirror::Object*>(old_lock_word.ForwardingAddress()); 1376 CHECK(to_ref != nullptr); 1377 CHECK_NE(to_ref, lost_fwd_ptr); 1378 CHECK(region_space_->IsInToSpace(to_ref) || heap_->non_moving_space_->HasAddress(to_ref)); 1379 CHECK_NE(to_ref->GetLockWord(false).GetState(), LockWord::kForwardingAddress); 1380 return to_ref; 1381 } 1382 1383 // Set the gray ptr. 1384 if (kUseBakerReadBarrier) { 1385 to_ref->SetReadBarrierPointer(ReadBarrier::GrayPtr()); 1386 } 1387 1388 LockWord new_lock_word = LockWord::FromForwardingAddress(reinterpret_cast<size_t>(to_ref)); 1389 1390 // Try to atomically write the fwd ptr. 1391 bool success = from_ref->CasLockWordWeakSequentiallyConsistent(old_lock_word, new_lock_word); 1392 if (LIKELY(success)) { 1393 // The CAS succeeded. 1394 objects_moved_.FetchAndAddSequentiallyConsistent(1); 1395 bytes_moved_.FetchAndAddSequentiallyConsistent(region_space_alloc_size); 1396 if (LIKELY(!fall_back_to_non_moving)) { 1397 DCHECK(region_space_->IsInToSpace(to_ref)); 1398 } else { 1399 DCHECK(heap_->non_moving_space_->HasAddress(to_ref)); 1400 DCHECK_EQ(bytes_allocated, non_moving_space_bytes_allocated); 1401 } 1402 if (kUseBakerReadBarrier) { 1403 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()); 1404 } 1405 DCHECK(GetFwdPtr(from_ref) == to_ref); 1406 CHECK_NE(to_ref->GetLockWord(false).GetState(), LockWord::kForwardingAddress); 1407 PushOntoMarkStack<true>(to_ref); 1408 return to_ref; 1409 } else { 1410 // The CAS failed. It may have lost the race or may have failed 1411 // due to monitor/hashcode ops. Either way, retry. 1412 } 1413 } 1414 } 1415 1416 mirror::Object* ConcurrentCopying::IsMarked(mirror::Object* from_ref) { 1417 DCHECK(from_ref != nullptr); 1418 space::RegionSpace::RegionType rtype = region_space_->GetRegionType(from_ref); 1419 if (rtype == space::RegionSpace::RegionType::kRegionTypeToSpace) { 1420 // It's already marked. 1421 return from_ref; 1422 } 1423 mirror::Object* to_ref; 1424 if (rtype == space::RegionSpace::RegionType::kRegionTypeFromSpace) { 1425 to_ref = GetFwdPtr(from_ref); 1426 DCHECK(to_ref == nullptr || region_space_->IsInToSpace(to_ref) || 1427 heap_->non_moving_space_->HasAddress(to_ref)) 1428 << "from_ref=" << from_ref << " to_ref=" << to_ref; 1429 } else if (rtype == space::RegionSpace::RegionType::kRegionTypeUnevacFromSpace) { 1430 if (region_space_bitmap_->Test(from_ref)) { 1431 to_ref = from_ref; 1432 } else { 1433 to_ref = nullptr; 1434 } 1435 } else { 1436 // from_ref is in a non-moving space. 1437 if (immune_region_.ContainsObject(from_ref)) { 1438 accounting::ContinuousSpaceBitmap* cc_bitmap = 1439 cc_heap_bitmap_->GetContinuousSpaceBitmap(from_ref); 1440 DCHECK(cc_bitmap != nullptr) 1441 << "An immune space object must have a bitmap"; 1442 if (kIsDebugBuild) { 1443 DCHECK(heap_mark_bitmap_->GetContinuousSpaceBitmap(from_ref)->Test(from_ref)) 1444 << "Immune space object must be already marked"; 1445 } 1446 if (cc_bitmap->Test(from_ref)) { 1447 // Already marked. 1448 to_ref = from_ref; 1449 } else { 1450 // Newly marked. 1451 to_ref = nullptr; 1452 } 1453 } else { 1454 // Non-immune non-moving space. Use the mark bitmap. 1455 accounting::ContinuousSpaceBitmap* mark_bitmap = 1456 heap_mark_bitmap_->GetContinuousSpaceBitmap(from_ref); 1457 accounting::LargeObjectBitmap* los_bitmap = 1458 heap_mark_bitmap_->GetLargeObjectBitmap(from_ref); 1459 CHECK(los_bitmap != nullptr) << "LOS bitmap covers the entire address range"; 1460 bool is_los = mark_bitmap == nullptr; 1461 if (!is_los && mark_bitmap->Test(from_ref)) { 1462 // Already marked. 1463 to_ref = from_ref; 1464 } else if (is_los && los_bitmap->Test(from_ref)) { 1465 // Already marked in LOS. 1466 to_ref = from_ref; 1467 } else { 1468 // Not marked. 1469 if (IsOnAllocStack(from_ref)) { 1470 // If on the allocation stack, it's considered marked. 1471 to_ref = from_ref; 1472 } else { 1473 // Not marked. 1474 to_ref = nullptr; 1475 } 1476 } 1477 } 1478 } 1479 return to_ref; 1480 } 1481 1482 bool ConcurrentCopying::IsOnAllocStack(mirror::Object* ref) { 1483 QuasiAtomic::ThreadFenceAcquire(); 1484 accounting::ObjectStack* alloc_stack = GetAllocationStack(); 1485 return alloc_stack->Contains(ref); 1486 } 1487 1488 mirror::Object* ConcurrentCopying::Mark(mirror::Object* from_ref) { 1489 if (from_ref == nullptr) { 1490 return nullptr; 1491 } 1492 DCHECK(from_ref != nullptr); 1493 DCHECK(heap_->collector_type_ == kCollectorTypeCC); 1494 if (kUseBakerReadBarrier && !is_active_) { 1495 // In the lock word forward address state, the read barrier bits 1496 // in the lock word are part of the stored forwarding address and 1497 // invalid. This is usually OK as the from-space copy of objects 1498 // aren't accessed by mutators due to the to-space 1499 // invariant. However, during the dex2oat image writing relocation 1500 // and the zygote compaction, objects can be in the forward 1501 // address state (to store the forward/relocation addresses) and 1502 // they can still be accessed and the invalid read barrier bits 1503 // are consulted. If they look like gray but aren't really, the 1504 // read barriers slow path can trigger when it shouldn't. To guard 1505 // against this, return here if the CC collector isn't running. 1506 return from_ref; 1507 } 1508 DCHECK(region_space_ != nullptr) << "Read barrier slow path taken when CC isn't running?"; 1509 space::RegionSpace::RegionType rtype = region_space_->GetRegionType(from_ref); 1510 if (rtype == space::RegionSpace::RegionType::kRegionTypeToSpace) { 1511 // It's already marked. 1512 return from_ref; 1513 } 1514 mirror::Object* to_ref; 1515 if (rtype == space::RegionSpace::RegionType::kRegionTypeFromSpace) { 1516 to_ref = GetFwdPtr(from_ref); 1517 if (kUseBakerReadBarrier) { 1518 DCHECK(to_ref != ReadBarrier::GrayPtr()) << "from_ref=" << from_ref << " to_ref=" << to_ref; 1519 } 1520 if (to_ref == nullptr) { 1521 // It isn't marked yet. Mark it by copying it to the to-space. 1522 to_ref = Copy(from_ref); 1523 } 1524 DCHECK(region_space_->IsInToSpace(to_ref) || heap_->non_moving_space_->HasAddress(to_ref)) 1525 << "from_ref=" << from_ref << " to_ref=" << to_ref; 1526 } else if (rtype == space::RegionSpace::RegionType::kRegionTypeUnevacFromSpace) { 1527 // This may or may not succeed, which is ok. 1528 if (kUseBakerReadBarrier) { 1529 from_ref->AtomicSetReadBarrierPointer(ReadBarrier::WhitePtr(), ReadBarrier::GrayPtr()); 1530 } 1531 if (region_space_bitmap_->AtomicTestAndSet(from_ref)) { 1532 // Already marked. 1533 to_ref = from_ref; 1534 } else { 1535 // Newly marked. 1536 to_ref = from_ref; 1537 if (kUseBakerReadBarrier) { 1538 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()); 1539 } 1540 PushOntoMarkStack<true>(to_ref); 1541 } 1542 } else { 1543 // from_ref is in a non-moving space. 1544 DCHECK(!region_space_->HasAddress(from_ref)) << from_ref; 1545 if (immune_region_.ContainsObject(from_ref)) { 1546 accounting::ContinuousSpaceBitmap* cc_bitmap = 1547 cc_heap_bitmap_->GetContinuousSpaceBitmap(from_ref); 1548 DCHECK(cc_bitmap != nullptr) 1549 << "An immune space object must have a bitmap"; 1550 if (kIsDebugBuild) { 1551 DCHECK(heap_mark_bitmap_->GetContinuousSpaceBitmap(from_ref)->Test(from_ref)) 1552 << "Immune space object must be already marked"; 1553 } 1554 // This may or may not succeed, which is ok. 1555 if (kUseBakerReadBarrier) { 1556 from_ref->AtomicSetReadBarrierPointer(ReadBarrier::WhitePtr(), ReadBarrier::GrayPtr()); 1557 } 1558 if (cc_bitmap->AtomicTestAndSet(from_ref)) { 1559 // Already marked. 1560 to_ref = from_ref; 1561 } else { 1562 // Newly marked. 1563 to_ref = from_ref; 1564 if (kUseBakerReadBarrier) { 1565 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()); 1566 } 1567 PushOntoMarkStack<true>(to_ref); 1568 } 1569 } else { 1570 // Use the mark bitmap. 1571 accounting::ContinuousSpaceBitmap* mark_bitmap = 1572 heap_mark_bitmap_->GetContinuousSpaceBitmap(from_ref); 1573 accounting::LargeObjectBitmap* los_bitmap = 1574 heap_mark_bitmap_->GetLargeObjectBitmap(from_ref); 1575 CHECK(los_bitmap != nullptr) << "LOS bitmap covers the entire address range"; 1576 bool is_los = mark_bitmap == nullptr; 1577 if (!is_los && mark_bitmap->Test(from_ref)) { 1578 // Already marked. 1579 to_ref = from_ref; 1580 if (kUseBakerReadBarrier) { 1581 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr() || 1582 to_ref->GetReadBarrierPointer() == ReadBarrier::BlackPtr()); 1583 } 1584 } else if (is_los && los_bitmap->Test(from_ref)) { 1585 // Already marked in LOS. 1586 to_ref = from_ref; 1587 if (kUseBakerReadBarrier) { 1588 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr() || 1589 to_ref->GetReadBarrierPointer() == ReadBarrier::BlackPtr()); 1590 } 1591 } else { 1592 // Not marked. 1593 if (IsOnAllocStack(from_ref)) { 1594 // If it's on the allocation stack, it's considered marked. Keep it white. 1595 to_ref = from_ref; 1596 // Objects on the allocation stack need not be marked. 1597 if (!is_los) { 1598 DCHECK(!mark_bitmap->Test(to_ref)); 1599 } else { 1600 DCHECK(!los_bitmap->Test(to_ref)); 1601 } 1602 if (kUseBakerReadBarrier) { 1603 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::WhitePtr()); 1604 } 1605 } else { 1606 // Not marked or on the allocation stack. Try to mark it. 1607 // This may or may not succeed, which is ok. 1608 if (kUseBakerReadBarrier) { 1609 from_ref->AtomicSetReadBarrierPointer(ReadBarrier::WhitePtr(), ReadBarrier::GrayPtr()); 1610 } 1611 if (!is_los && mark_bitmap->AtomicTestAndSet(from_ref)) { 1612 // Already marked. 1613 to_ref = from_ref; 1614 } else if (is_los && los_bitmap->AtomicTestAndSet(from_ref)) { 1615 // Already marked in LOS. 1616 to_ref = from_ref; 1617 } else { 1618 // Newly marked. 1619 to_ref = from_ref; 1620 if (kUseBakerReadBarrier) { 1621 DCHECK(to_ref->GetReadBarrierPointer() == ReadBarrier::GrayPtr()); 1622 } 1623 PushOntoMarkStack<true>(to_ref); 1624 } 1625 } 1626 } 1627 } 1628 } 1629 return to_ref; 1630 } 1631 1632 void ConcurrentCopying::FinishPhase() { 1633 region_space_ = nullptr; 1634 CHECK(mark_queue_.IsEmpty()); 1635 mark_queue_.Clear(); 1636 { 1637 MutexLock mu(Thread::Current(), skipped_blocks_lock_); 1638 skipped_blocks_map_.clear(); 1639 } 1640 WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_); 1641 heap_->ClearMarkedObjects(); 1642 } 1643 1644 mirror::Object* ConcurrentCopying::IsMarkedCallback(mirror::Object* from_ref, void* arg) { 1645 return reinterpret_cast<ConcurrentCopying*>(arg)->IsMarked(from_ref); 1646 } 1647 1648 bool ConcurrentCopying::IsHeapReferenceMarkedCallback( 1649 mirror::HeapReference<mirror::Object>* field, void* arg) { 1650 mirror::Object* from_ref = field->AsMirrorPtr(); 1651 mirror::Object* to_ref = reinterpret_cast<ConcurrentCopying*>(arg)->IsMarked(from_ref); 1652 if (to_ref == nullptr) { 1653 return false; 1654 } 1655 if (from_ref != to_ref) { 1656 QuasiAtomic::ThreadFenceRelease(); 1657 field->Assign(to_ref); 1658 QuasiAtomic::ThreadFenceSequentiallyConsistent(); 1659 } 1660 return true; 1661 } 1662 1663 mirror::Object* ConcurrentCopying::MarkCallback(mirror::Object* from_ref, void* arg) { 1664 return reinterpret_cast<ConcurrentCopying*>(arg)->Mark(from_ref); 1665 } 1666 1667 void ConcurrentCopying::ProcessMarkStackCallback(void* arg) { 1668 reinterpret_cast<ConcurrentCopying*>(arg)->ProcessMarkStack(); 1669 } 1670 1671 void ConcurrentCopying::DelayReferenceReferent(mirror::Class* klass, mirror::Reference* reference) { 1672 heap_->GetReferenceProcessor()->DelayReferenceReferent( 1673 klass, reference, &IsHeapReferenceMarkedCallback, this); 1674 } 1675 1676 void ConcurrentCopying::ProcessReferences(Thread* self, bool concurrent) { 1677 TimingLogger::ScopedTiming split("ProcessReferences", GetTimings()); 1678 WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); 1679 GetHeap()->GetReferenceProcessor()->ProcessReferences( 1680 concurrent, GetTimings(), GetCurrentIteration()->GetClearSoftReferences(), 1681 &IsHeapReferenceMarkedCallback, &MarkCallback, &ProcessMarkStackCallback, this); 1682 } 1683 1684 void ConcurrentCopying::RevokeAllThreadLocalBuffers() { 1685 TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); 1686 region_space_->RevokeAllThreadLocalBuffers(); 1687 } 1688 1689 } // namespace collector 1690 } // namespace gc 1691 } // namespace art 1692