241 lines
8.3 KiB
C++
241 lines
8.3 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
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#define ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
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#include <array>
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#include <string_view>
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#include "base/atomic.h"
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#include "base/locks.h" // For Locks::mutator_lock_.
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#include "heap_poisoning.h"
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#include "obj_ptr.h"
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#include "runtime_globals.h"
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namespace art {
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namespace mirror {
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class Object;
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// Classes shared with the managed side of the world need to be packed so that they don't have
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// extra platform specific padding.
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#define MANAGED PACKED(4)
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#define MIRROR_CLASS(desc) \
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static_assert(::art::mirror::IsMirroredDescriptor(desc), \
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desc " is not a known mirror class. Please update" \
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" IsMirroredDescriptor to include it!")
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constexpr bool IsMirroredDescriptor(std::string_view desc) {
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if (desc[0] != 'L') {
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// All primitives and arrays are mirrored
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return true;
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}
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#define MIRROR_DESCRIPTORS(vis) \
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vis("Ljava/lang/Class;") \
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vis("Ljava/lang/ClassLoader;") \
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vis("Ljava/lang/ClassNotFoundException;") \
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vis("Ljava/lang/DexCache;") \
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vis("Ljava/lang/Object;") \
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vis("Ljava/lang/StackTraceElement;") \
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vis("Ljava/lang/String;") \
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vis("Ljava/lang/Throwable;") \
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vis("Ljava/lang/invoke/ArrayElementVarHandle;") \
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vis("Ljava/lang/invoke/ByteArrayViewVarHandle;") \
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vis("Ljava/lang/invoke/ByteBufferViewVarHandle;") \
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vis("Ljava/lang/invoke/CallSite;") \
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vis("Ljava/lang/invoke/FieldVarHandle;") \
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vis("Ljava/lang/invoke/StaticFieldVarHandle;") \
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vis("Ljava/lang/invoke/MethodHandle;") \
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vis("Ljava/lang/invoke/MethodHandleImpl;") \
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vis("Ljava/lang/invoke/MethodHandles$Lookup;") \
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vis("Ljava/lang/invoke/MethodType;") \
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vis("Ljava/lang/invoke/VarHandle;") \
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vis("Ljava/lang/ref/FinalizerReference;") \
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vis("Ljava/lang/ref/Reference;") \
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vis("Ljava/lang/reflect/AccessibleObject;") \
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vis("Ljava/lang/reflect/Constructor;") \
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vis("Ljava/lang/reflect/Executable;") \
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vis("Ljava/lang/reflect/Field;") \
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vis("Ljava/lang/reflect/Method;") \
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vis("Ljava/lang/reflect/Proxy;") \
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vis("Ldalvik/system/ClassExt;") \
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vis("Ldalvik/system/EmulatedStackFrame;")
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// TODO: Once we are C++ 20 we can just have a constexpr array and std::find.
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// constexpr std::array<std::string_view, 28> kMirrorTypes{
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// // Fill in
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// };
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// return std::find(kMirrorTypes.begin(), kMirrorTypes.end(), desc) != kMirrorTypes.end();
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#define CHECK_DESCRIPTOR(descriptor) \
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if (std::string_view(descriptor) == desc) { \
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return true; \
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}
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MIRROR_DESCRIPTORS(CHECK_DESCRIPTOR)
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#undef CHECK_DESCRIPTOR
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return false;
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#undef MIRROR_DESCRIPTORS
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}
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template<bool kPoisonReferences, class MirrorType>
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class PtrCompression {
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public:
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// Compress reference to its bit representation.
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static uint32_t Compress(MirrorType* mirror_ptr) {
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uintptr_t as_bits = reinterpret_cast<uintptr_t>(mirror_ptr);
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return static_cast<uint32_t>(kPoisonReferences ? -as_bits : as_bits);
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}
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// Uncompress an encoded reference from its bit representation.
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static MirrorType* Decompress(uint32_t ref) {
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uintptr_t as_bits = kPoisonReferences ? -ref : ref;
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return reinterpret_cast<MirrorType*>(as_bits);
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}
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// Convert an ObjPtr to a compressed reference.
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static uint32_t Compress(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_);
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};
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// Value type representing a reference to a mirror::Object of type MirrorType.
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template<bool kPoisonReferences, class MirrorType>
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class MANAGED ObjectReference {
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private:
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using Compression = PtrCompression<kPoisonReferences, MirrorType>;
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public:
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/*
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* Returns a pointer to the mirror of the managed object this reference is for.
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*
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* This does NOT return the current object (which isn't derived from, and
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* therefor cannot be a mirror::Object) as a mirror pointer. Instead, this
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* returns a pointer to the mirror of the managed object this refers to.
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*
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* TODO (chriswailes): Rename to GetPtr().
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*/
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MirrorType* AsMirrorPtr() const {
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return Compression::Decompress(reference_);
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}
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void Assign(MirrorType* other) {
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reference_ = Compression::Compress(other);
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}
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void Assign(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_);
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void Clear() {
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reference_ = 0;
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DCHECK(IsNull());
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}
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bool IsNull() const {
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return reference_ == 0;
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}
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uint32_t AsVRegValue() const {
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return reference_;
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}
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static ObjectReference<kPoisonReferences, MirrorType> FromMirrorPtr(MirrorType* mirror_ptr)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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return ObjectReference<kPoisonReferences, MirrorType>(mirror_ptr);
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}
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protected:
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explicit ObjectReference(MirrorType* mirror_ptr) REQUIRES_SHARED(Locks::mutator_lock_)
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: reference_(Compression::Compress(mirror_ptr)) {
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}
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// The encoded reference to a mirror::Object.
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uint32_t reference_;
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};
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// References between objects within the managed heap.
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// Similar API to ObjectReference, but not a value type. Supports atomic access.
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template<class MirrorType>
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class MANAGED HeapReference {
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private:
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using Compression = PtrCompression<kPoisonHeapReferences, MirrorType>;
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public:
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HeapReference() REQUIRES_SHARED(Locks::mutator_lock_) : HeapReference(nullptr) {}
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template <bool kIsVolatile = false>
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MirrorType* AsMirrorPtr() const REQUIRES_SHARED(Locks::mutator_lock_) {
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return Compression::Decompress(
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kIsVolatile ? reference_.load(std::memory_order_seq_cst) : reference_.LoadJavaData());
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}
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template <bool kIsVolatile = false>
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void Assign(MirrorType* other) REQUIRES_SHARED(Locks::mutator_lock_) {
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if (kIsVolatile) {
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reference_.store(Compression::Compress(other), std::memory_order_seq_cst);
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} else {
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reference_.StoreJavaData(Compression::Compress(other));
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}
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}
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template <bool kIsVolatile = false>
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void Assign(ObjPtr<MirrorType> ptr) REQUIRES_SHARED(Locks::mutator_lock_);
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void Clear() {
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reference_.StoreJavaData(0);
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DCHECK(IsNull());
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}
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bool IsNull() const {
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return reference_.LoadJavaData() == 0;
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}
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static HeapReference<MirrorType> FromMirrorPtr(MirrorType* mirror_ptr)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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return HeapReference<MirrorType>(mirror_ptr);
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}
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bool CasWeakRelaxed(MirrorType* old_ptr, MirrorType* new_ptr)
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REQUIRES_SHARED(Locks::mutator_lock_);
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private:
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explicit HeapReference(MirrorType* mirror_ptr) REQUIRES_SHARED(Locks::mutator_lock_)
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: reference_(Compression::Compress(mirror_ptr)) {}
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// The encoded reference to a mirror::Object. Atomically updateable.
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Atomic<uint32_t> reference_;
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};
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static_assert(sizeof(mirror::HeapReference<mirror::Object>) == kHeapReferenceSize,
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"heap reference size does not match");
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// Standard compressed reference used in the runtime. Used for StackReference and GC roots.
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template<class MirrorType>
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class MANAGED CompressedReference : public mirror::ObjectReference<false, MirrorType> {
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public:
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CompressedReference<MirrorType>() REQUIRES_SHARED(Locks::mutator_lock_)
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: mirror::ObjectReference<false, MirrorType>(nullptr) {}
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static CompressedReference<MirrorType> FromMirrorPtr(MirrorType* p)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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return CompressedReference<MirrorType>(p);
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}
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private:
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explicit CompressedReference(MirrorType* p) REQUIRES_SHARED(Locks::mutator_lock_)
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: mirror::ObjectReference<false, MirrorType>(p) {}
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};
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} // namespace mirror
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} // namespace art
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#endif // ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
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