| /* |
| * 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_MIRROR_OBJECT_REFERENCE_H_ |
| #define ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_ |
| |
| #include "atomic.h" |
| #include "base/mutex.h" // For Locks::mutator_lock_. |
| #include "globals.h" |
| #include "heap_poisoning.h" |
| #include "obj_ptr.h" |
| |
| namespace art { |
| namespace mirror { |
| |
| class Object; |
| |
| // Classes shared with the managed side of the world need to be packed so that they don't have |
| // extra platform specific padding. |
| #define MANAGED PACKED(4) |
| |
| template<bool kPoisonReferences, class MirrorType> |
| class PtrCompression { |
| public: |
| // Compress reference to its bit representation. |
| static uint32_t Compress(MirrorType* mirror_ptr) { |
| uintptr_t as_bits = reinterpret_cast<uintptr_t>(mirror_ptr); |
| return static_cast<uint32_t>(kPoisonReferences ? -as_bits : as_bits); |
| } |
| |
| // Uncompress an encoded reference from its bit representation. |
| static MirrorType* Decompress(uint32_t ref) { |
| uintptr_t as_bits = kPoisonReferences ? -ref : ref; |
| return reinterpret_cast<MirrorType*>(as_bits); |
| } |
| |
| // Convert an ObjPtr to a compressed reference. |
| static uint32_t Compress(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_) { |
| return Compress(ptr.Ptr()); |
| } |
| }; |
| |
| // Value type representing a reference to a mirror::Object of type MirrorType. |
| template<bool kPoisonReferences, class MirrorType> |
| class MANAGED ObjectReference { |
| private: |
| using Compression = PtrCompression<kPoisonReferences, MirrorType>; |
| |
| public: |
| MirrorType* AsMirrorPtr() const { |
| return Compression::Decompress(reference_); |
| } |
| |
| void Assign(MirrorType* other) { |
| reference_ = Compression::Compress(other); |
| } |
| |
| void Assign(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| void Clear() { |
| reference_ = 0; |
| DCHECK(IsNull()); |
| } |
| |
| bool IsNull() const { |
| return reference_ == 0; |
| } |
| |
| uint32_t AsVRegValue() const { |
| return reference_; |
| } |
| |
| static ObjectReference<kPoisonReferences, MirrorType> FromMirrorPtr(MirrorType* mirror_ptr) |
| REQUIRES_SHARED(Locks::mutator_lock_) { |
| return ObjectReference<kPoisonReferences, MirrorType>(mirror_ptr); |
| } |
| |
| protected: |
| explicit ObjectReference(MirrorType* mirror_ptr) REQUIRES_SHARED(Locks::mutator_lock_) |
| : reference_(Compression::Compress(mirror_ptr)) { |
| } |
| |
| // The encoded reference to a mirror::Object. |
| uint32_t reference_; |
| }; |
| |
| // References between objects within the managed heap. |
| // Similar API to ObjectReference, but not a value type. Supports atomic access. |
| template<class MirrorType> |
| class MANAGED HeapReference { |
| private: |
| using Compression = PtrCompression<kPoisonHeapReferences, MirrorType>; |
| |
| public: |
| HeapReference() REQUIRES_SHARED(Locks::mutator_lock_) : HeapReference(nullptr) {} |
| |
| template <bool kIsVolatile = false> |
| MirrorType* AsMirrorPtr() const REQUIRES_SHARED(Locks::mutator_lock_) { |
| return Compression::Decompress( |
| kIsVolatile ? reference_.LoadSequentiallyConsistent() : reference_.LoadJavaData()); |
| } |
| |
| template <bool kIsVolatile = false> |
| void Assign(MirrorType* other) REQUIRES_SHARED(Locks::mutator_lock_) { |
| if (kIsVolatile) { |
| reference_.StoreSequentiallyConsistent(Compression::Compress(other)); |
| } else { |
| reference_.StoreJavaData(Compression::Compress(other)); |
| } |
| } |
| |
| template <bool kIsVolatile = false> |
| void Assign(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| void Clear() { |
| reference_.StoreJavaData(0); |
| DCHECK(IsNull()); |
| } |
| |
| bool IsNull() const { |
| return reference_.LoadJavaData() == 0; |
| } |
| |
| static HeapReference<MirrorType> FromMirrorPtr(MirrorType* mirror_ptr) |
| REQUIRES_SHARED(Locks::mutator_lock_) { |
| return HeapReference<MirrorType>(mirror_ptr); |
| } |
| |
| bool CasWeakRelaxed(MirrorType* old_ptr, MirrorType* new_ptr) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| private: |
| explicit HeapReference(MirrorType* mirror_ptr) REQUIRES_SHARED(Locks::mutator_lock_) |
| : reference_(Compression::Compress(mirror_ptr)) {} |
| |
| // The encoded reference to a mirror::Object. Atomically updateable. |
| Atomic<uint32_t> reference_; |
| }; |
| |
| static_assert(sizeof(mirror::HeapReference<mirror::Object>) == kHeapReferenceSize, |
| "heap reference size does not match"); |
| |
| // Standard compressed reference used in the runtime. Used for StackReference and GC roots. |
| template<class MirrorType> |
| class MANAGED CompressedReference : public mirror::ObjectReference<false, MirrorType> { |
| public: |
| CompressedReference<MirrorType>() REQUIRES_SHARED(Locks::mutator_lock_) |
| : mirror::ObjectReference<false, MirrorType>(nullptr) {} |
| |
| static CompressedReference<MirrorType> FromMirrorPtr(MirrorType* p) |
| REQUIRES_SHARED(Locks::mutator_lock_) { |
| return CompressedReference<MirrorType>(p); |
| } |
| |
| private: |
| explicit CompressedReference(MirrorType* p) REQUIRES_SHARED(Locks::mutator_lock_) |
| : mirror::ObjectReference<false, MirrorType>(p) {} |
| }; |
| |
| } // namespace mirror |
| } // namespace art |
| |
| #endif // ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_ |