| /* |
| * 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 <array> |
| #include <string_view> |
| |
| #include "base/atomic.h" |
| #include "base/locks.h" // For Locks::mutator_lock_. |
| #include "heap_poisoning.h" |
| #include "obj_ptr.h" |
| #include "runtime_globals.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) |
| #define MIRROR_CLASS(desc) \ |
| static_assert(::art::mirror::IsMirroredDescriptor(desc), \ |
| desc " is not a known mirror class. Please update" \ |
| " IsMirroredDescriptor to include it!") |
| |
| constexpr bool IsMirroredDescriptor(std::string_view desc) { |
| if (desc[0] != 'L') { |
| // All primitives and arrays are mirrored |
| return true; |
| } |
| #define MIRROR_DESCRIPTORS(vis) \ |
| vis("Ljava/lang/Class;") \ |
| vis("Ljava/lang/ClassLoader;") \ |
| vis("Ljava/lang/ClassNotFoundException;") \ |
| vis("Ljava/lang/DexCache;") \ |
| vis("Ljava/lang/Object;") \ |
| vis("Ljava/lang/StackTraceElement;") \ |
| vis("Ljava/lang/String;") \ |
| vis("Ljava/lang/Throwable;") \ |
| vis("Ljava/lang/invoke/ArrayElementVarHandle;") \ |
| vis("Ljava/lang/invoke/ByteArrayViewVarHandle;") \ |
| vis("Ljava/lang/invoke/ByteBufferViewVarHandle;") \ |
| vis("Ljava/lang/invoke/CallSite;") \ |
| vis("Ljava/lang/invoke/FieldVarHandle;") \ |
| vis("Ljava/lang/invoke/MethodHandle;") \ |
| vis("Ljava/lang/invoke/MethodHandleImpl;") \ |
| vis("Ljava/lang/invoke/MethodHandles$Lookup;") \ |
| vis("Ljava/lang/invoke/MethodType;") \ |
| vis("Ljava/lang/invoke/VarHandle;") \ |
| vis("Ljava/lang/ref/FinalizerReference;") \ |
| vis("Ljava/lang/ref/Reference;") \ |
| vis("Ljava/lang/reflect/AccessibleObject;") \ |
| vis("Ljava/lang/reflect/Constructor;") \ |
| vis("Ljava/lang/reflect/Executable;") \ |
| vis("Ljava/lang/reflect/Field;") \ |
| vis("Ljava/lang/reflect/Method;") \ |
| vis("Ljava/lang/reflect/Proxy;") \ |
| vis("Ldalvik/system/ClassExt;") \ |
| vis("Ldalvik/system/EmulatedStackFrame;") |
| // TODO: Once we are C++ 20 we can just have a constexpr array and std::find. |
| // constexpr std::array<std::string_view, 28> kMirrorTypes{ |
| // // Fill in |
| // }; |
| // return std::find(kMirrorTypes.begin(), kMirrorTypes.end(), desc) != kMirrorTypes.end(); |
| #define CHECK_DESCRIPTOR(descriptor) \ |
| if (std::string_view(descriptor) == desc) { \ |
| return true; \ |
| } |
| MIRROR_DESCRIPTORS(CHECK_DESCRIPTOR) |
| #undef CHECK_DESCRIPTOR |
| return false; |
| #undef MIRROR_DESCRIPTORS |
| } |
| |
| 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_); |
| }; |
| |
| // 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: |
| /* |
| * Returns a pointer to the mirror of the managed object this reference is for. |
| * |
| * This does NOT return the current object (which isn't derived from, and |
| * therefor cannot be a mirror::Object) as a mirror pointer. Instead, this |
| * returns a pointer to the mirror of the managed object this refers to. |
| * |
| * TODO (chriswailes): Rename to GetPtr(). |
| */ |
| 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_.load(std::memory_order_seq_cst) : reference_.LoadJavaData()); |
| } |
| |
| template <bool kIsVolatile = false> |
| void Assign(MirrorType* other) REQUIRES_SHARED(Locks::mutator_lock_) { |
| if (kIsVolatile) { |
| reference_.store(Compression::Compress(other), std::memory_order_seq_cst); |
| } 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_ |