| /* |
| * Copyright (C) 2013 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "semi_space-inl.h" |
| |
| #include <climits> |
| #include <functional> |
| #include <numeric> |
| #include <sstream> |
| #include <vector> |
| |
| #include "base/logging.h" |
| #include "base/macros.h" |
| #include "base/mutex-inl.h" |
| #include "base/timing_logger.h" |
| #include "gc/accounting/heap_bitmap-inl.h" |
| #include "gc/accounting/mod_union_table.h" |
| #include "gc/accounting/remembered_set.h" |
| #include "gc/accounting/space_bitmap-inl.h" |
| #include "gc/heap.h" |
| #include "gc/reference_processor.h" |
| #include "gc/space/bump_pointer_space.h" |
| #include "gc/space/bump_pointer_space-inl.h" |
| #include "gc/space/image_space.h" |
| #include "gc/space/large_object_space.h" |
| #include "gc/space/space-inl.h" |
| #include "indirect_reference_table.h" |
| #include "intern_table.h" |
| #include "jni_internal.h" |
| #include "mark_sweep-inl.h" |
| #include "monitor.h" |
| #include "mirror/reference-inl.h" |
| #include "mirror/object-inl.h" |
| #include "runtime.h" |
| #include "thread-inl.h" |
| #include "thread_list.h" |
| |
| using ::art::mirror::Object; |
| |
| namespace art { |
| namespace gc { |
| namespace collector { |
| |
| static constexpr bool kProtectFromSpace = true; |
| static constexpr bool kStoreStackTraces = false; |
| static constexpr size_t kBytesPromotedThreshold = 4 * MB; |
| static constexpr size_t kLargeObjectBytesAllocatedThreshold = 16 * MB; |
| |
| void SemiSpace::BindBitmaps() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| WriterMutexLock mu(self_, *Locks::heap_bitmap_lock_); |
| // Mark all of the spaces we never collect as immune. |
| for (const auto& space : GetHeap()->GetContinuousSpaces()) { |
| if (space->GetGcRetentionPolicy() == space::kGcRetentionPolicyNeverCollect || |
| space->GetGcRetentionPolicy() == space::kGcRetentionPolicyFullCollect) { |
| immune_spaces_.AddSpace(space); |
| } else if (space->GetLiveBitmap() != nullptr) { |
| // TODO: We can probably also add this space to the immune region. |
| if (space == to_space_ || collect_from_space_only_) { |
| if (collect_from_space_only_) { |
| // Bind the bitmaps of the main free list space and the non-moving space we are doing a |
| // bump pointer space only collection. |
| CHECK(space == GetHeap()->GetPrimaryFreeListSpace() || |
| space == GetHeap()->GetNonMovingSpace()); |
| } |
| CHECK(space->IsContinuousMemMapAllocSpace()); |
| space->AsContinuousMemMapAllocSpace()->BindLiveToMarkBitmap(); |
| } |
| } |
| } |
| if (collect_from_space_only_) { |
| // We won't collect the large object space if a bump pointer space only collection. |
| is_large_object_space_immune_ = true; |
| } |
| } |
| |
| SemiSpace::SemiSpace(Heap* heap, bool generational, const std::string& name_prefix) |
| : GarbageCollector(heap, |
| name_prefix + (name_prefix.empty() ? "" : " ") + "semispace"), |
| mark_stack_(nullptr), |
| is_large_object_space_immune_(false), |
| to_space_(nullptr), |
| to_space_live_bitmap_(nullptr), |
| from_space_(nullptr), |
| mark_bitmap_(nullptr), |
| self_(nullptr), |
| generational_(generational), |
| last_gc_to_space_end_(nullptr), |
| bytes_promoted_(0), |
| bytes_promoted_since_last_whole_heap_collection_(0), |
| large_object_bytes_allocated_at_last_whole_heap_collection_(0), |
| collect_from_space_only_(generational), |
| promo_dest_space_(nullptr), |
| fallback_space_(nullptr), |
| bytes_moved_(0U), |
| objects_moved_(0U), |
| saved_bytes_(0U), |
| collector_name_(name_), |
| swap_semi_spaces_(true) { |
| } |
| |
| void SemiSpace::RunPhases() { |
| Thread* self = Thread::Current(); |
| InitializePhase(); |
| // Semi-space collector is special since it is sometimes called with the mutators suspended |
| // during the zygote creation and collector transitions. If we already exclusively hold the |
| // mutator lock, then we can't lock it again since it will cause a deadlock. |
| if (Locks::mutator_lock_->IsExclusiveHeld(self)) { |
| GetHeap()->PreGcVerificationPaused(this); |
| GetHeap()->PrePauseRosAllocVerification(this); |
| MarkingPhase(); |
| ReclaimPhase(); |
| GetHeap()->PostGcVerificationPaused(this); |
| } else { |
| Locks::mutator_lock_->AssertNotHeld(self); |
| { |
| ScopedPause pause(this); |
| GetHeap()->PreGcVerificationPaused(this); |
| GetHeap()->PrePauseRosAllocVerification(this); |
| MarkingPhase(); |
| } |
| { |
| ReaderMutexLock mu(self, *Locks::mutator_lock_); |
| ReclaimPhase(); |
| } |
| GetHeap()->PostGcVerification(this); |
| } |
| FinishPhase(); |
| } |
| |
| void SemiSpace::InitializePhase() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| mark_stack_ = heap_->GetMarkStack(); |
| DCHECK(mark_stack_ != nullptr); |
| immune_spaces_.Reset(); |
| is_large_object_space_immune_ = false; |
| saved_bytes_ = 0; |
| bytes_moved_ = 0; |
| objects_moved_ = 0; |
| self_ = Thread::Current(); |
| CHECK(from_space_->CanMoveObjects()) << "Attempting to move from " << *from_space_; |
| // Set the initial bitmap. |
| to_space_live_bitmap_ = to_space_->GetLiveBitmap(); |
| { |
| // TODO: I don't think we should need heap bitmap lock to Get the mark bitmap. |
| ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_); |
| mark_bitmap_ = heap_->GetMarkBitmap(); |
| } |
| if (generational_) { |
| promo_dest_space_ = GetHeap()->GetPrimaryFreeListSpace(); |
| } |
| fallback_space_ = GetHeap()->GetNonMovingSpace(); |
| } |
| |
| void SemiSpace::ProcessReferences(Thread* self) { |
| WriterMutexLock mu(self, *Locks::heap_bitmap_lock_); |
| GetHeap()->GetReferenceProcessor()->ProcessReferences( |
| false, GetTimings(), GetCurrentIteration()->GetClearSoftReferences(), this); |
| } |
| |
| void SemiSpace::MarkingPhase() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| CHECK(Locks::mutator_lock_->IsExclusiveHeld(self_)); |
| if (kStoreStackTraces) { |
| Locks::mutator_lock_->AssertExclusiveHeld(self_); |
| // Store the stack traces into the runtime fault string in case we Get a heap corruption |
| // related crash later. |
| ThreadState old_state = self_->SetStateUnsafe(kRunnable); |
| std::ostringstream oss; |
| Runtime* runtime = Runtime::Current(); |
| runtime->GetThreadList()->DumpForSigQuit(oss); |
| runtime->GetThreadList()->DumpNativeStacks(oss); |
| runtime->SetFaultMessage(oss.str()); |
| CHECK_EQ(self_->SetStateUnsafe(old_state), kRunnable); |
| } |
| // Revoke the thread local buffers since the GC may allocate into a RosAllocSpace and this helps |
| // to prevent fragmentation. |
| RevokeAllThreadLocalBuffers(); |
| if (generational_) { |
| if (GetCurrentIteration()->GetGcCause() == kGcCauseExplicit || |
| GetCurrentIteration()->GetGcCause() == kGcCauseForNativeAlloc || |
| GetCurrentIteration()->GetClearSoftReferences()) { |
| // If an explicit, native allocation-triggered, or last attempt |
| // collection, collect the whole heap. |
| collect_from_space_only_ = false; |
| } |
| if (!collect_from_space_only_) { |
| VLOG(heap) << "Whole heap collection"; |
| name_ = collector_name_ + " whole"; |
| } else { |
| VLOG(heap) << "Bump pointer space only collection"; |
| name_ = collector_name_ + " bps"; |
| } |
| } |
| |
| if (!collect_from_space_only_) { |
| // If non-generational, always clear soft references. |
| // If generational, clear soft references if a whole heap collection. |
| GetCurrentIteration()->SetClearSoftReferences(true); |
| } |
| Locks::mutator_lock_->AssertExclusiveHeld(self_); |
| if (generational_) { |
| // If last_gc_to_space_end_ is out of the bounds of the from-space |
| // (the to-space from last GC), then point it to the beginning of |
| // the from-space. For example, the very first GC or the |
| // pre-zygote compaction. |
| if (!from_space_->HasAddress(reinterpret_cast<mirror::Object*>(last_gc_to_space_end_))) { |
| last_gc_to_space_end_ = from_space_->Begin(); |
| } |
| // Reset this before the marking starts below. |
| bytes_promoted_ = 0; |
| } |
| // Assume the cleared space is already empty. |
| BindBitmaps(); |
| // Process dirty cards and add dirty cards to mod-union tables. |
| heap_->ProcessCards(GetTimings(), kUseRememberedSet && generational_, false, true); |
| // Clear the whole card table since we cannot get any additional dirty cards during the |
| // paused GC. This saves memory but only works for pause the world collectors. |
| t.NewTiming("ClearCardTable"); |
| heap_->GetCardTable()->ClearCardTable(); |
| // Need to do this before the checkpoint since we don't want any threads to add references to |
| // the live stack during the recursive mark. |
| if (kUseThreadLocalAllocationStack) { |
| TimingLogger::ScopedTiming t2("RevokeAllThreadLocalAllocationStacks", GetTimings()); |
| heap_->RevokeAllThreadLocalAllocationStacks(self_); |
| } |
| heap_->SwapStacks(); |
| { |
| WriterMutexLock mu(self_, *Locks::heap_bitmap_lock_); |
| MarkRoots(); |
| // Recursively mark remaining objects. |
| MarkReachableObjects(); |
| } |
| ProcessReferences(self_); |
| { |
| ReaderMutexLock mu(self_, *Locks::heap_bitmap_lock_); |
| SweepSystemWeaks(); |
| } |
| Runtime::Current()->GetClassLinker()->CleanupClassLoaders(); |
| // Revoke buffers before measuring how many objects were moved since the TLABs need to be revoked |
| // before they are properly counted. |
| RevokeAllThreadLocalBuffers(); |
| GetHeap()->RecordFreeRevoke(); // this is for the non-moving rosalloc space used by GSS. |
| // Record freed memory. |
| const int64_t from_bytes = from_space_->GetBytesAllocated(); |
| const int64_t to_bytes = bytes_moved_; |
| const uint64_t from_objects = from_space_->GetObjectsAllocated(); |
| const uint64_t to_objects = objects_moved_; |
| CHECK_LE(to_objects, from_objects); |
| // Note: Freed bytes can be negative if we copy form a compacted space to a free-list backed |
| // space. |
| RecordFree(ObjectBytePair(from_objects - to_objects, from_bytes - to_bytes)); |
| // Clear and protect the from space. |
| from_space_->Clear(); |
| // b/31172841. Temporarily disable the from-space protection with host debug build |
| // due to some protection issue in the build server. |
| if (kProtectFromSpace && !(kIsDebugBuild && !kIsTargetBuild)) { |
| if (!from_space_->IsRosAllocSpace()) { |
| // Protect with PROT_NONE. |
| VLOG(heap) << "Protecting from_space_ : " << *from_space_; |
| from_space_->GetMemMap()->Protect(PROT_NONE); |
| } else { |
| // If RosAllocSpace, we'll leave it as PROT_READ here so the |
| // rosaloc verification can read the metadata magic number and |
| // protect it with PROT_NONE later in FinishPhase(). |
| VLOG(heap) << "Protecting from_space_ with PROT_READ : " << *from_space_; |
| from_space_->GetMemMap()->Protect(PROT_READ); |
| } |
| } |
| heap_->PreSweepingGcVerification(this); |
| if (swap_semi_spaces_) { |
| heap_->SwapSemiSpaces(); |
| } |
| } |
| |
| // Used to verify that there's no references to the from-space. |
| class SemiSpace::VerifyNoFromSpaceReferencesVisitor { |
| public: |
| explicit VerifyNoFromSpaceReferencesVisitor(space::ContinuousMemMapAllocSpace* from_space) |
| : from_space_(from_space) {} |
| |
| void operator()(Object* obj, MemberOffset offset, bool /* is_static */) const |
| REQUIRES_SHARED(Locks::mutator_lock_) ALWAYS_INLINE { |
| mirror::Object* ref = obj->GetFieldObject<mirror::Object>(offset); |
| if (from_space_->HasAddress(ref)) { |
| LOG(FATAL) << ref << " found in from space"; |
| } |
| } |
| |
| // TODO: Remove NO_THREAD_SAFETY_ANALYSIS when clang better understands visitors. |
| void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const |
| NO_THREAD_SAFETY_ANALYSIS { |
| if (!root->IsNull()) { |
| VisitRoot(root); |
| } |
| } |
| |
| void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const |
| NO_THREAD_SAFETY_ANALYSIS { |
| if (kIsDebugBuild) { |
| Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current()); |
| Locks::heap_bitmap_lock_->AssertExclusiveHeld(Thread::Current()); |
| } |
| CHECK(!from_space_->HasAddress(root->AsMirrorPtr())); |
| } |
| |
| private: |
| space::ContinuousMemMapAllocSpace* const from_space_; |
| }; |
| |
| void SemiSpace::VerifyNoFromSpaceReferences(Object* obj) { |
| DCHECK(!from_space_->HasAddress(obj)) << "Scanning object " << obj << " in from space"; |
| VerifyNoFromSpaceReferencesVisitor visitor(from_space_); |
| obj->VisitReferences(visitor, VoidFunctor()); |
| } |
| |
| void SemiSpace::MarkReachableObjects() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| { |
| TimingLogger::ScopedTiming t2("MarkStackAsLive", GetTimings()); |
| accounting::ObjectStack* live_stack = heap_->GetLiveStack(); |
| heap_->MarkAllocStackAsLive(live_stack); |
| live_stack->Reset(); |
| } |
| for (auto& space : heap_->GetContinuousSpaces()) { |
| // If the space is immune then we need to mark the references to other spaces. |
| accounting::ModUnionTable* table = heap_->FindModUnionTableFromSpace(space); |
| if (table != nullptr) { |
| // TODO: Improve naming. |
| TimingLogger::ScopedTiming t2( |
| space->IsZygoteSpace() ? "UpdateAndMarkZygoteModUnionTable" : |
| "UpdateAndMarkImageModUnionTable", |
| GetTimings()); |
| table->UpdateAndMarkReferences(this); |
| DCHECK(GetHeap()->FindRememberedSetFromSpace(space) == nullptr); |
| } else if ((space->IsImageSpace() || collect_from_space_only_) && |
| space->GetLiveBitmap() != nullptr) { |
| // If the space has no mod union table (the non-moving space, app image spaces, main spaces |
| // when the bump pointer space only collection is enabled,) then we need to scan its live |
| // bitmap or dirty cards as roots (including the objects on the live stack which have just |
| // marked in the live bitmap above in MarkAllocStackAsLive().) |
| accounting::RememberedSet* rem_set = GetHeap()->FindRememberedSetFromSpace(space); |
| if (!space->IsImageSpace()) { |
| DCHECK(space == heap_->GetNonMovingSpace() || space == heap_->GetPrimaryFreeListSpace()) |
| << "Space " << space->GetName() << " " |
| << "generational_=" << generational_ << " " |
| << "collect_from_space_only_=" << collect_from_space_only_; |
| // App images currently do not have remembered sets. |
| DCHECK_EQ(kUseRememberedSet, rem_set != nullptr); |
| } else { |
| DCHECK(rem_set == nullptr); |
| } |
| if (rem_set != nullptr) { |
| TimingLogger::ScopedTiming t2("UpdateAndMarkRememberedSet", GetTimings()); |
| rem_set->UpdateAndMarkReferences(from_space_, this); |
| } else { |
| TimingLogger::ScopedTiming t2("VisitLiveBits", GetTimings()); |
| accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap(); |
| live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()), |
| reinterpret_cast<uintptr_t>(space->End()), |
| [this](mirror::Object* obj) |
| REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_) { |
| ScanObject(obj); |
| }); |
| } |
| if (kIsDebugBuild) { |
| // Verify that there are no from-space references that |
| // remain in the space, that is, the remembered set (and the |
| // card table) didn't miss any from-space references in the |
| // space. |
| accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap(); |
| live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()), |
| reinterpret_cast<uintptr_t>(space->End()), |
| [this](Object* obj) |
| REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) { |
| DCHECK(obj != nullptr); |
| VerifyNoFromSpaceReferences(obj); |
| }); |
| } |
| } |
| } |
| |
| CHECK_EQ(is_large_object_space_immune_, collect_from_space_only_); |
| space::LargeObjectSpace* los = GetHeap()->GetLargeObjectsSpace(); |
| if (is_large_object_space_immune_ && los != nullptr) { |
| TimingLogger::ScopedTiming t2("VisitLargeObjects", GetTimings()); |
| DCHECK(collect_from_space_only_); |
| // Delay copying the live set to the marked set until here from |
| // BindBitmaps() as the large objects on the allocation stack may |
| // be newly added to the live set above in MarkAllocStackAsLive(). |
| los->CopyLiveToMarked(); |
| |
| // When the large object space is immune, we need to scan the |
| // large object space as roots as they contain references to their |
| // classes (primitive array classes) that could move though they |
| // don't contain any other references. |
| accounting::LargeObjectBitmap* large_live_bitmap = los->GetLiveBitmap(); |
| std::pair<uint8_t*, uint8_t*> range = los->GetBeginEndAtomic(); |
| large_live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(range.first), |
| reinterpret_cast<uintptr_t>(range.second), |
| [this](mirror::Object* obj) |
| REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_) { |
| ScanObject(obj); |
| }); |
| } |
| // Recursively process the mark stack. |
| ProcessMarkStack(); |
| } |
| |
| void SemiSpace::ReclaimPhase() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| WriterMutexLock mu(self_, *Locks::heap_bitmap_lock_); |
| // Reclaim unmarked objects. |
| Sweep(false); |
| // Swap the live and mark bitmaps for each space which we modified space. This is an |
| // optimization that enables us to not clear live bits inside of the sweep. Only swaps unbound |
| // bitmaps. |
| SwapBitmaps(); |
| // Unbind the live and mark bitmaps. |
| GetHeap()->UnBindBitmaps(); |
| if (saved_bytes_ > 0) { |
| VLOG(heap) << "Avoided dirtying " << PrettySize(saved_bytes_); |
| } |
| if (generational_) { |
| // Record the end (top) of the to space so we can distinguish |
| // between objects that were allocated since the last GC and the |
| // older objects. |
| last_gc_to_space_end_ = to_space_->End(); |
| } |
| } |
| |
| void SemiSpace::ResizeMarkStack(size_t new_size) { |
| std::vector<StackReference<Object>> temp(mark_stack_->Begin(), mark_stack_->End()); |
| CHECK_LE(mark_stack_->Size(), new_size); |
| mark_stack_->Resize(new_size); |
| for (auto& obj : temp) { |
| mark_stack_->PushBack(obj.AsMirrorPtr()); |
| } |
| } |
| |
| inline void SemiSpace::MarkStackPush(Object* obj) { |
| if (UNLIKELY(mark_stack_->Size() >= mark_stack_->Capacity())) { |
| ResizeMarkStack(mark_stack_->Capacity() * 2); |
| } |
| // The object must be pushed on to the mark stack. |
| mark_stack_->PushBack(obj); |
| } |
| |
| static inline size_t CopyAvoidingDirtyingPages(void* dest, const void* src, size_t size) { |
| if (LIKELY(size <= static_cast<size_t>(kPageSize))) { |
| // We will dirty the current page and somewhere in the middle of the next page. This means |
| // that the next object copied will also dirty that page. |
| // TODO: Worth considering the last object copied? We may end up dirtying one page which is |
| // not necessary per GC. |
| memcpy(dest, src, size); |
| return 0; |
| } |
| size_t saved_bytes = 0; |
| uint8_t* byte_dest = reinterpret_cast<uint8_t*>(dest); |
| if (kIsDebugBuild) { |
| for (size_t i = 0; i < size; ++i) { |
| CHECK_EQ(byte_dest[i], 0U); |
| } |
| } |
| // Process the start of the page. The page must already be dirty, don't bother with checking. |
| const uint8_t* byte_src = reinterpret_cast<const uint8_t*>(src); |
| const uint8_t* limit = byte_src + size; |
| size_t page_remain = AlignUp(byte_dest, kPageSize) - byte_dest; |
| // Copy the bytes until the start of the next page. |
| memcpy(dest, src, page_remain); |
| byte_src += page_remain; |
| byte_dest += page_remain; |
| DCHECK_ALIGNED(reinterpret_cast<uintptr_t>(byte_dest), kPageSize); |
| DCHECK_ALIGNED(reinterpret_cast<uintptr_t>(byte_dest), sizeof(uintptr_t)); |
| DCHECK_ALIGNED(reinterpret_cast<uintptr_t>(byte_src), sizeof(uintptr_t)); |
| while (byte_src + kPageSize < limit) { |
| bool all_zero = true; |
| uintptr_t* word_dest = reinterpret_cast<uintptr_t*>(byte_dest); |
| const uintptr_t* word_src = reinterpret_cast<const uintptr_t*>(byte_src); |
| for (size_t i = 0; i < kPageSize / sizeof(*word_src); ++i) { |
| // Assumes the destination of the copy is all zeros. |
| if (word_src[i] != 0) { |
| all_zero = false; |
| word_dest[i] = word_src[i]; |
| } |
| } |
| if (all_zero) { |
| // Avoided copying into the page since it was all zeros. |
| saved_bytes += kPageSize; |
| } |
| byte_src += kPageSize; |
| byte_dest += kPageSize; |
| } |
| // Handle the part of the page at the end. |
| memcpy(byte_dest, byte_src, limit - byte_src); |
| return saved_bytes; |
| } |
| |
| mirror::Object* SemiSpace::MarkNonForwardedObject(mirror::Object* obj) { |
| const size_t object_size = obj->SizeOf(); |
| size_t bytes_allocated, dummy; |
| mirror::Object* forward_address = nullptr; |
| if (generational_ && reinterpret_cast<uint8_t*>(obj) < last_gc_to_space_end_) { |
| // If it's allocated before the last GC (older), move |
| // (pseudo-promote) it to the main free list space (as sort |
| // of an old generation.) |
| forward_address = promo_dest_space_->AllocThreadUnsafe(self_, object_size, &bytes_allocated, |
| nullptr, &dummy); |
| if (UNLIKELY(forward_address == nullptr)) { |
| // If out of space, fall back to the to-space. |
| forward_address = to_space_->AllocThreadUnsafe(self_, object_size, &bytes_allocated, nullptr, |
| &dummy); |
| // No logic for marking the bitmap, so it must be null. |
| DCHECK(to_space_live_bitmap_ == nullptr); |
| } else { |
| bytes_promoted_ += bytes_allocated; |
| // Dirty the card at the destionation as it may contain |
| // references (including the class pointer) to the bump pointer |
| // space. |
| GetHeap()->WriteBarrierEveryFieldOf(forward_address); |
| // Handle the bitmaps marking. |
| accounting::ContinuousSpaceBitmap* live_bitmap = promo_dest_space_->GetLiveBitmap(); |
| DCHECK(live_bitmap != nullptr); |
| accounting::ContinuousSpaceBitmap* mark_bitmap = promo_dest_space_->GetMarkBitmap(); |
| DCHECK(mark_bitmap != nullptr); |
| DCHECK(!live_bitmap->Test(forward_address)); |
| if (collect_from_space_only_) { |
| // If collecting the bump pointer spaces only, live_bitmap == mark_bitmap. |
| DCHECK_EQ(live_bitmap, mark_bitmap); |
| |
| // If a bump pointer space only collection, delay the live |
| // bitmap marking of the promoted object until it's popped off |
| // the mark stack (ProcessMarkStack()). The rationale: we may |
| // be in the middle of scanning the objects in the promo |
| // destination space for |
| // non-moving-space-to-bump-pointer-space references by |
| // iterating over the marked bits of the live bitmap |
| // (MarkReachableObjects()). If we don't delay it (and instead |
| // mark the promoted object here), the above promo destination |
| // space scan could encounter the just-promoted object and |
| // forward the references in the promoted object's fields even |
| // through it is pushed onto the mark stack. If this happens, |
| // the promoted object would be in an inconsistent state, that |
| // is, it's on the mark stack (gray) but its fields are |
| // already forwarded (black), which would cause a |
| // DCHECK(!to_space_->HasAddress(obj)) failure below. |
| } else { |
| // Mark forward_address on the live bit map. |
| live_bitmap->Set(forward_address); |
| // Mark forward_address on the mark bit map. |
| DCHECK(!mark_bitmap->Test(forward_address)); |
| mark_bitmap->Set(forward_address); |
| } |
| } |
| } else { |
| // If it's allocated after the last GC (younger), copy it to the to-space. |
| forward_address = to_space_->AllocThreadUnsafe(self_, object_size, &bytes_allocated, nullptr, |
| &dummy); |
| if (forward_address != nullptr && to_space_live_bitmap_ != nullptr) { |
| to_space_live_bitmap_->Set(forward_address); |
| } |
| } |
| // If it's still null, attempt to use the fallback space. |
| if (UNLIKELY(forward_address == nullptr)) { |
| forward_address = fallback_space_->AllocThreadUnsafe(self_, object_size, &bytes_allocated, |
| nullptr, &dummy); |
| CHECK(forward_address != nullptr) << "Out of memory in the to-space and fallback space."; |
| accounting::ContinuousSpaceBitmap* bitmap = fallback_space_->GetLiveBitmap(); |
| if (bitmap != nullptr) { |
| bitmap->Set(forward_address); |
| } |
| } |
| ++objects_moved_; |
| bytes_moved_ += bytes_allocated; |
| // Copy over the object and add it to the mark stack since we still need to update its |
| // references. |
| saved_bytes_ += |
| CopyAvoidingDirtyingPages(reinterpret_cast<void*>(forward_address), obj, object_size); |
| if (kUseBakerReadBarrier) { |
| obj->AssertReadBarrierState(); |
| forward_address->AssertReadBarrierState(); |
| } |
| DCHECK(to_space_->HasAddress(forward_address) || |
| fallback_space_->HasAddress(forward_address) || |
| (generational_ && promo_dest_space_->HasAddress(forward_address))) |
| << forward_address << "\n" << GetHeap()->DumpSpaces(); |
| return forward_address; |
| } |
| |
| mirror::Object* SemiSpace::MarkObject(mirror::Object* root) { |
| auto ref = StackReference<mirror::Object>::FromMirrorPtr(root); |
| MarkObjectIfNotInToSpace(&ref); |
| return ref.AsMirrorPtr(); |
| } |
| |
| void SemiSpace::MarkHeapReference(mirror::HeapReference<mirror::Object>* obj_ptr, |
| bool do_atomic_update ATTRIBUTE_UNUSED) { |
| MarkObject(obj_ptr); |
| } |
| |
| void SemiSpace::VisitRoots(mirror::Object*** roots, size_t count, |
| const RootInfo& info ATTRIBUTE_UNUSED) { |
| for (size_t i = 0; i < count; ++i) { |
| auto* root = roots[i]; |
| auto ref = StackReference<mirror::Object>::FromMirrorPtr(*root); |
| // The root can be in the to-space since we may visit the declaring class of an ArtMethod |
| // multiple times if it is on the call stack. |
| MarkObjectIfNotInToSpace(&ref); |
| if (*root != ref.AsMirrorPtr()) { |
| *root = ref.AsMirrorPtr(); |
| } |
| } |
| } |
| |
| void SemiSpace::VisitRoots(mirror::CompressedReference<mirror::Object>** roots, size_t count, |
| const RootInfo& info ATTRIBUTE_UNUSED) { |
| for (size_t i = 0; i < count; ++i) { |
| MarkObjectIfNotInToSpace(roots[i]); |
| } |
| } |
| |
| // Marks all objects in the root set. |
| void SemiSpace::MarkRoots() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| Runtime::Current()->VisitRoots(this); |
| } |
| |
| void SemiSpace::SweepSystemWeaks() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| Runtime::Current()->SweepSystemWeaks(this); |
| } |
| |
| bool SemiSpace::ShouldSweepSpace(space::ContinuousSpace* space) const { |
| return space != from_space_ && space != to_space_; |
| } |
| |
| void SemiSpace::Sweep(bool swap_bitmaps) { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| DCHECK(mark_stack_->IsEmpty()); |
| for (const auto& space : GetHeap()->GetContinuousSpaces()) { |
| if (space->IsContinuousMemMapAllocSpace()) { |
| space::ContinuousMemMapAllocSpace* alloc_space = space->AsContinuousMemMapAllocSpace(); |
| if (!ShouldSweepSpace(alloc_space)) { |
| continue; |
| } |
| TimingLogger::ScopedTiming split( |
| alloc_space->IsZygoteSpace() ? "SweepZygoteSpace" : "SweepAllocSpace", GetTimings()); |
| RecordFree(alloc_space->Sweep(swap_bitmaps)); |
| } |
| } |
| if (!is_large_object_space_immune_) { |
| SweepLargeObjects(swap_bitmaps); |
| } |
| } |
| |
| void SemiSpace::SweepLargeObjects(bool swap_bitmaps) { |
| DCHECK(!is_large_object_space_immune_); |
| space::LargeObjectSpace* los = heap_->GetLargeObjectsSpace(); |
| if (los != nullptr) { |
| TimingLogger::ScopedTiming split("SweepLargeObjects", GetTimings()); |
| RecordFreeLOS(los->Sweep(swap_bitmaps)); |
| } |
| } |
| |
| // Process the "referent" field in a java.lang.ref.Reference. If the referent has not yet been |
| // marked, put it on the appropriate list in the heap for later processing. |
| void SemiSpace::DelayReferenceReferent(ObjPtr<mirror::Class> klass, |
| ObjPtr<mirror::Reference> reference) { |
| heap_->GetReferenceProcessor()->DelayReferenceReferent(klass, reference, this); |
| } |
| |
| class SemiSpace::MarkObjectVisitor { |
| public: |
| explicit MarkObjectVisitor(SemiSpace* collector) : collector_(collector) {} |
| |
| void operator()(ObjPtr<Object> obj, MemberOffset offset, bool /* is_static */) const ALWAYS_INLINE |
| REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_) { |
| // Object was already verified when we scanned it. |
| collector_->MarkObject(obj->GetFieldObjectReferenceAddr<kVerifyNone>(offset)); |
| } |
| |
| void operator()(ObjPtr<mirror::Class> klass, ObjPtr<mirror::Reference> ref) const |
| REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_) { |
| collector_->DelayReferenceReferent(klass, ref); |
| } |
| |
| // TODO: Remove NO_THREAD_SAFETY_ANALYSIS when clang better understands visitors. |
| void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const |
| NO_THREAD_SAFETY_ANALYSIS { |
| if (!root->IsNull()) { |
| VisitRoot(root); |
| } |
| } |
| |
| void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const |
| NO_THREAD_SAFETY_ANALYSIS { |
| if (kIsDebugBuild) { |
| Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current()); |
| Locks::heap_bitmap_lock_->AssertExclusiveHeld(Thread::Current()); |
| } |
| // We may visit the same root multiple times, so avoid marking things in the to-space since |
| // this is not handled by the GC. |
| collector_->MarkObjectIfNotInToSpace(root); |
| } |
| |
| private: |
| SemiSpace* const collector_; |
| }; |
| |
| // Visit all of the references of an object and update. |
| void SemiSpace::ScanObject(Object* obj) { |
| DCHECK(!from_space_->HasAddress(obj)) << "Scanning object " << obj << " in from space"; |
| MarkObjectVisitor visitor(this); |
| // Turn off read barrier. ZygoteCompactingCollector doesn't use it (even in the CC build.) |
| obj->VisitReferences</*kVisitNativeRoots*/true, kDefaultVerifyFlags, kWithoutReadBarrier>( |
| visitor, visitor); |
| } |
| |
| // Scan anything that's on the mark stack. |
| void SemiSpace::ProcessMarkStack() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| accounting::ContinuousSpaceBitmap* live_bitmap = nullptr; |
| if (collect_from_space_only_) { |
| // If a bump pointer space only collection (and the promotion is |
| // enabled,) we delay the live-bitmap marking of promoted objects |
| // from MarkObject() until this function. |
| live_bitmap = promo_dest_space_->GetLiveBitmap(); |
| DCHECK(live_bitmap != nullptr); |
| accounting::ContinuousSpaceBitmap* mark_bitmap = promo_dest_space_->GetMarkBitmap(); |
| DCHECK(mark_bitmap != nullptr); |
| DCHECK_EQ(live_bitmap, mark_bitmap); |
| } |
| while (!mark_stack_->IsEmpty()) { |
| Object* obj = mark_stack_->PopBack(); |
| if (collect_from_space_only_ && promo_dest_space_->HasAddress(obj)) { |
| // obj has just been promoted. Mark the live bitmap for it, |
| // which is delayed from MarkObject(). |
| DCHECK(!live_bitmap->Test(obj)); |
| live_bitmap->Set(obj); |
| } |
| ScanObject(obj); |
| } |
| } |
| |
| mirror::Object* SemiSpace::IsMarked(mirror::Object* obj) { |
| // All immune objects are assumed marked. |
| if (from_space_->HasAddress(obj)) { |
| // Returns either the forwarding address or null. |
| return GetForwardingAddressInFromSpace(obj); |
| } else if (collect_from_space_only_ || |
| immune_spaces_.IsInImmuneRegion(obj) || |
| to_space_->HasAddress(obj)) { |
| return obj; // Already forwarded, must be marked. |
| } |
| return mark_bitmap_->Test(obj) ? obj : nullptr; |
| } |
| |
| bool SemiSpace::IsNullOrMarkedHeapReference(mirror::HeapReference<mirror::Object>* object, |
| // SemiSpace does the GC in a pause. No CAS needed. |
| bool do_atomic_update ATTRIBUTE_UNUSED) { |
| mirror::Object* obj = object->AsMirrorPtr(); |
| if (obj == nullptr) { |
| return true; |
| } |
| mirror::Object* new_obj = IsMarked(obj); |
| if (new_obj == nullptr) { |
| return false; |
| } |
| if (new_obj != obj) { |
| // Write barrier is not necessary since it still points to the same object, just at a different |
| // address. |
| object->Assign(new_obj); |
| } |
| return true; |
| } |
| |
| void SemiSpace::SetToSpace(space::ContinuousMemMapAllocSpace* to_space) { |
| DCHECK(to_space != nullptr); |
| to_space_ = to_space; |
| } |
| |
| void SemiSpace::SetFromSpace(space::ContinuousMemMapAllocSpace* from_space) { |
| DCHECK(from_space != nullptr); |
| from_space_ = from_space; |
| } |
| |
| void SemiSpace::FinishPhase() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| // b/31172841. Temporarily disable the from-space protection with host debug build |
| // due to some protection issue in the build server. |
| if (kProtectFromSpace && !(kIsDebugBuild && !kIsTargetBuild)) { |
| if (from_space_->IsRosAllocSpace()) { |
| VLOG(heap) << "Protecting from_space_ with PROT_NONE : " << *from_space_; |
| from_space_->GetMemMap()->Protect(PROT_NONE); |
| } |
| } |
| // Null the "to" and "from" spaces since compacting from one to the other isn't valid until |
| // further action is done by the heap. |
| to_space_ = nullptr; |
| from_space_ = nullptr; |
| CHECK(mark_stack_->IsEmpty()); |
| mark_stack_->Reset(); |
| space::LargeObjectSpace* los = GetHeap()->GetLargeObjectsSpace(); |
| if (generational_) { |
| // Decide whether to do a whole heap collection or a bump pointer |
| // only space collection at the next collection by updating |
| // collect_from_space_only_. |
| if (collect_from_space_only_) { |
| // Disable collect_from_space_only_ if the bytes promoted since the |
| // last whole heap collection or the large object bytes |
| // allocated exceeds a threshold. |
| bytes_promoted_since_last_whole_heap_collection_ += bytes_promoted_; |
| bool bytes_promoted_threshold_exceeded = |
| bytes_promoted_since_last_whole_heap_collection_ >= kBytesPromotedThreshold; |
| uint64_t current_los_bytes_allocated = los != nullptr ? los->GetBytesAllocated() : 0U; |
| uint64_t last_los_bytes_allocated = |
| large_object_bytes_allocated_at_last_whole_heap_collection_; |
| bool large_object_bytes_threshold_exceeded = |
| current_los_bytes_allocated >= |
| last_los_bytes_allocated + kLargeObjectBytesAllocatedThreshold; |
| if (bytes_promoted_threshold_exceeded || large_object_bytes_threshold_exceeded) { |
| collect_from_space_only_ = false; |
| } |
| } else { |
| // Reset the counters. |
| bytes_promoted_since_last_whole_heap_collection_ = bytes_promoted_; |
| large_object_bytes_allocated_at_last_whole_heap_collection_ = |
| los != nullptr ? los->GetBytesAllocated() : 0U; |
| collect_from_space_only_ = true; |
| } |
| } |
| // Clear all of the spaces' mark bitmaps. |
| WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_); |
| heap_->ClearMarkedObjects(); |
| } |
| |
| void SemiSpace::RevokeAllThreadLocalBuffers() { |
| TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings()); |
| GetHeap()->RevokeAllThreadLocalBuffers(); |
| } |
| |
| } // namespace collector |
| } // namespace gc |
| } // namespace art |