| /* |
| * Copyright (C) 2014 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. |
| */ |
| |
| #ifndef ART_RUNTIME_READ_BARRIER_INL_H_ |
| #define ART_RUNTIME_READ_BARRIER_INL_H_ |
| |
| #include "read_barrier.h" |
| |
| #include "gc/accounting/read_barrier_table.h" |
| #include "gc/collector/concurrent_copying-inl.h" |
| #include "gc/heap.h" |
| #include "mirror/object-readbarrier-inl.h" |
| #include "mirror/object_reference.h" |
| #include "mirror/reference.h" |
| #include "runtime.h" |
| |
| namespace art { |
| |
| // Disabled for performance reasons. |
| static constexpr bool kCheckDebugDisallowReadBarrierCount = false; |
| |
| template <typename MirrorType, bool kIsVolatile, ReadBarrierOption kReadBarrierOption, |
| bool kAlwaysUpdateField> |
| inline MirrorType* ReadBarrier::Barrier( |
| mirror::Object* obj, MemberOffset offset, mirror::HeapReference<MirrorType>* ref_addr) { |
| constexpr bool with_read_barrier = kReadBarrierOption == kWithReadBarrier; |
| if (kUseReadBarrier && with_read_barrier) { |
| if (kCheckDebugDisallowReadBarrierCount) { |
| Thread* const self = Thread::Current(); |
| if (self != nullptr) { |
| CHECK_EQ(self->GetDebugDisallowReadBarrierCount(), 0u); |
| } |
| } |
| if (kUseBakerReadBarrier) { |
| // fake_address_dependency (must be zero) is used to create artificial data dependency from |
| // the is_gray load to the ref field (ptr) load to avoid needing a load-load barrier between |
| // the two. |
| uintptr_t fake_address_dependency; |
| bool is_gray = IsGray(obj, &fake_address_dependency); |
| if (kEnableReadBarrierInvariantChecks) { |
| CHECK_EQ(fake_address_dependency, 0U) << obj << " rb_state=" << obj->GetReadBarrierState(); |
| } |
| ref_addr = reinterpret_cast<mirror::HeapReference<MirrorType>*>( |
| fake_address_dependency | reinterpret_cast<uintptr_t>(ref_addr)); |
| MirrorType* ref = ref_addr->template AsMirrorPtr<kIsVolatile>(); |
| MirrorType* old_ref = ref; |
| if (is_gray) { |
| // Slow-path. |
| ref = reinterpret_cast<MirrorType*>(Mark(ref)); |
| // If kAlwaysUpdateField is true, update the field atomically. This may fail if mutator |
| // updates before us, but it's OK. |
| if (kAlwaysUpdateField && ref != old_ref) { |
| obj->CasFieldObjectWithoutWriteBarrier<false, false>(offset, |
| old_ref, |
| ref, |
| CASMode::kStrong, |
| std::memory_order_release); |
| } |
| } |
| AssertToSpaceInvariant(obj, offset, ref); |
| return ref; |
| } else if (kUseBrooksReadBarrier) { |
| // To be implemented. |
| return ref_addr->template AsMirrorPtr<kIsVolatile>(); |
| } else if (kUseTableLookupReadBarrier) { |
| MirrorType* ref = ref_addr->template AsMirrorPtr<kIsVolatile>(); |
| MirrorType* old_ref = ref; |
| // The heap or the collector can be null at startup. TODO: avoid the need for this null check. |
| gc::Heap* heap = Runtime::Current()->GetHeap(); |
| if (heap != nullptr && heap->GetReadBarrierTable()->IsSet(old_ref)) { |
| ref = reinterpret_cast<MirrorType*>(Mark(old_ref)); |
| // Update the field atomically. This may fail if mutator updates before us, but it's ok. |
| if (ref != old_ref) { |
| obj->CasFieldObjectWithoutWriteBarrier<false, false>(offset, |
| old_ref, |
| ref, |
| CASMode::kStrong, |
| std::memory_order_release); |
| } |
| } |
| AssertToSpaceInvariant(obj, offset, ref); |
| return ref; |
| } else { |
| LOG(FATAL) << "Unexpected read barrier type"; |
| UNREACHABLE(); |
| } |
| } else { |
| // No read barrier. |
| return ref_addr->template AsMirrorPtr<kIsVolatile>(); |
| } |
| } |
| |
| template <typename MirrorType, ReadBarrierOption kReadBarrierOption> |
| inline MirrorType* ReadBarrier::BarrierForRoot(MirrorType** root, |
| GcRootSource* gc_root_source) { |
| MirrorType* ref = *root; |
| const bool with_read_barrier = kReadBarrierOption == kWithReadBarrier; |
| if (kUseReadBarrier && with_read_barrier) { |
| if (kIsDebugBuild) { |
| Thread* const self = Thread::Current(); |
| if (self != nullptr) { |
| CHECK_EQ(self->GetDebugDisallowReadBarrierCount(), 0u); |
| } |
| } |
| if (kUseBakerReadBarrier) { |
| // TODO: separate the read barrier code from the collector code more. |
| Thread* self = Thread::Current(); |
| if (self != nullptr && self->GetIsGcMarking()) { |
| ref = reinterpret_cast<MirrorType*>(Mark(ref)); |
| } |
| AssertToSpaceInvariant(gc_root_source, ref); |
| return ref; |
| } else if (kUseBrooksReadBarrier) { |
| // To be implemented. |
| return ref; |
| } else if (kUseTableLookupReadBarrier) { |
| Thread* self = Thread::Current(); |
| if (self != nullptr && |
| self->GetIsGcMarking() && |
| Runtime::Current()->GetHeap()->GetReadBarrierTable()->IsSet(ref)) { |
| MirrorType* old_ref = ref; |
| ref = reinterpret_cast<MirrorType*>(Mark(old_ref)); |
| // Update the field atomically. This may fail if mutator updates before us, but it's ok. |
| if (ref != old_ref) { |
| Atomic<MirrorType*>* atomic_root = reinterpret_cast<Atomic<MirrorType*>*>(root); |
| atomic_root->CompareAndSetStrongRelaxed(old_ref, ref); |
| } |
| } |
| AssertToSpaceInvariant(gc_root_source, ref); |
| return ref; |
| } else { |
| LOG(FATAL) << "Unexpected read barrier type"; |
| UNREACHABLE(); |
| } |
| } else { |
| return ref; |
| } |
| } |
| |
| // TODO: Reduce copy paste |
| template <typename MirrorType, ReadBarrierOption kReadBarrierOption> |
| inline MirrorType* ReadBarrier::BarrierForRoot(mirror::CompressedReference<MirrorType>* root, |
| GcRootSource* gc_root_source) { |
| MirrorType* ref = root->AsMirrorPtr(); |
| const bool with_read_barrier = kReadBarrierOption == kWithReadBarrier; |
| if (with_read_barrier && kUseBakerReadBarrier) { |
| // TODO: separate the read barrier code from the collector code more. |
| Thread* self = Thread::Current(); |
| if (self != nullptr && self->GetIsGcMarking()) { |
| ref = reinterpret_cast<MirrorType*>(Mark(ref)); |
| } |
| AssertToSpaceInvariant(gc_root_source, ref); |
| return ref; |
| } else if (with_read_barrier && kUseBrooksReadBarrier) { |
| // To be implemented. |
| return ref; |
| } else if (with_read_barrier && kUseTableLookupReadBarrier) { |
| Thread* self = Thread::Current(); |
| if (self != nullptr && |
| self->GetIsGcMarking() && |
| Runtime::Current()->GetHeap()->GetReadBarrierTable()->IsSet(ref)) { |
| auto old_ref = mirror::CompressedReference<MirrorType>::FromMirrorPtr(ref); |
| ref = reinterpret_cast<MirrorType*>(Mark(ref)); |
| auto new_ref = mirror::CompressedReference<MirrorType>::FromMirrorPtr(ref); |
| // Update the field atomically. This may fail if mutator updates before us, but it's ok. |
| if (new_ref.AsMirrorPtr() != old_ref.AsMirrorPtr()) { |
| auto* atomic_root = |
| reinterpret_cast<Atomic<mirror::CompressedReference<MirrorType>>*>(root); |
| atomic_root->CompareAndSetStrongRelaxed(old_ref, new_ref); |
| } |
| } |
| AssertToSpaceInvariant(gc_root_source, ref); |
| return ref; |
| } else { |
| return ref; |
| } |
| } |
| |
| template <typename MirrorType> |
| inline MirrorType* ReadBarrier::IsMarked(MirrorType* ref) { |
| // Only read-barrier configurations can have mutators run while |
| // the GC is marking. |
| if (!kUseReadBarrier) { |
| return ref; |
| } |
| // IsMarked does not handle null, so handle it here. |
| if (ref == nullptr) { |
| return nullptr; |
| } |
| // IsMarked should only be called when the GC is marking. |
| if (!Thread::Current()->GetIsGcMarking()) { |
| return ref; |
| } |
| |
| return reinterpret_cast<MirrorType*>( |
| Runtime::Current()->GetHeap()->ConcurrentCopyingCollector()->IsMarked(ref)); |
| } |
| |
| inline bool ReadBarrier::IsDuringStartup() { |
| gc::Heap* heap = Runtime::Current()->GetHeap(); |
| if (heap == nullptr) { |
| // During startup, the heap can be null. |
| return true; |
| } |
| if (heap->CurrentCollectorType() != gc::kCollectorTypeCC) { |
| // CC isn't running. |
| return true; |
| } |
| gc::collector::ConcurrentCopying* collector = heap->ConcurrentCopyingCollector(); |
| if (collector == nullptr) { |
| // During startup, the collector can be null. |
| return true; |
| } |
| return false; |
| } |
| |
| inline void ReadBarrier::AssertToSpaceInvariant(mirror::Object* obj, MemberOffset offset, |
| mirror::Object* ref) { |
| if (kEnableToSpaceInvariantChecks) { |
| if (ref == nullptr || IsDuringStartup()) { |
| return; |
| } |
| Runtime::Current()->GetHeap()->ConcurrentCopyingCollector()-> |
| AssertToSpaceInvariant(obj, offset, ref); |
| } |
| } |
| |
| inline void ReadBarrier::AssertToSpaceInvariant(GcRootSource* gc_root_source, |
| mirror::Object* ref) { |
| if (kEnableToSpaceInvariantChecks) { |
| if (ref == nullptr || IsDuringStartup()) { |
| return; |
| } |
| Runtime::Current()->GetHeap()->ConcurrentCopyingCollector()-> |
| AssertToSpaceInvariant(gc_root_source, ref); |
| } |
| } |
| |
| inline mirror::Object* ReadBarrier::Mark(mirror::Object* obj) { |
| return Runtime::Current()->GetHeap()->ConcurrentCopyingCollector()->MarkFromReadBarrier(obj); |
| } |
| |
| inline bool ReadBarrier::IsGray(mirror::Object* obj, uintptr_t* fake_address_dependency) { |
| return obj->GetReadBarrierState(fake_address_dependency) == kGrayState; |
| } |
| |
| inline bool ReadBarrier::IsGray(mirror::Object* obj) { |
| // Use a load-acquire to load the read barrier bit to avoid reordering with the subsequent load. |
| // GetReadBarrierStateAcquire() has load-acquire semantics. |
| return obj->GetReadBarrierStateAcquire() == kGrayState; |
| } |
| |
| } // namespace art |
| |
| #endif // ART_RUNTIME_READ_BARRIER_INL_H_ |