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/*
* 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_H_
#define ART_RUNTIME_READ_BARRIER_H_
#include "base/mutex.h"
#include "base/macros.h"
#include "gc_root.h"
#include "jni.h"
#include "mirror/object_reference.h"
#include "offsets.h"
#include "read_barrier_c.h"
// This is a C++ (not C) header file, separate from read_barrier_c.h
// which needs to be a C header file for asm_support.h.
namespace art {
namespace mirror {
class Object;
template<typename MirrorType> class HeapReference;
} // namespace mirror
class ArtMethod;
class ReadBarrier {
public:
// Enable the to-space invariant checks.
static constexpr bool kEnableToSpaceInvariantChecks = kIsDebugBuild;
// Enable the read barrier checks.
static constexpr bool kEnableReadBarrierInvariantChecks = kIsDebugBuild;
// It's up to the implementation whether the given field gets updated whereas the return value
// must be an updated reference unless kAlwaysUpdateField is true.
template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier,
bool kAlwaysUpdateField = false>
ALWAYS_INLINE static MirrorType* Barrier(
mirror::Object* obj, MemberOffset offset, mirror::HeapReference<MirrorType>* ref_addr)
SHARED_REQUIRES(Locks::mutator_lock_);
// It's up to the implementation whether the given root gets updated
// whereas the return value must be an updated reference.
template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
ALWAYS_INLINE static MirrorType* BarrierForRoot(MirrorType** root,
GcRootSource* gc_root_source = nullptr)
SHARED_REQUIRES(Locks::mutator_lock_);
// It's up to the implementation whether the given root gets updated
// whereas the return value must be an updated reference.
template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
ALWAYS_INLINE static MirrorType* BarrierForRoot(mirror::CompressedReference<MirrorType>* root,
GcRootSource* gc_root_source = nullptr)
SHARED_REQUIRES(Locks::mutator_lock_);
static bool IsDuringStartup();
// Without the holder object.
static void AssertToSpaceInvariant(mirror::Object* ref)
SHARED_REQUIRES(Locks::mutator_lock_) {
AssertToSpaceInvariant(nullptr, MemberOffset(0), ref);
}
// With the holder object.
static void AssertToSpaceInvariant(mirror::Object* obj, MemberOffset offset,
mirror::Object* ref)
SHARED_REQUIRES(Locks::mutator_lock_);
// With GcRootSource.
static void AssertToSpaceInvariant(GcRootSource* gc_root_source, mirror::Object* ref)
SHARED_REQUIRES(Locks::mutator_lock_);
// ALWAYS_INLINE on this caused a performance regression b/26744236.
static mirror::Object* Mark(mirror::Object* obj) SHARED_REQUIRES(Locks::mutator_lock_);
static mirror::Object* WhitePtr() {
return reinterpret_cast<mirror::Object*>(white_ptr_);
}
static mirror::Object* GrayPtr() {
return reinterpret_cast<mirror::Object*>(gray_ptr_);
}
static mirror::Object* BlackPtr() {
return reinterpret_cast<mirror::Object*>(black_ptr_);
}
ALWAYS_INLINE static bool HasGrayReadBarrierPointer(mirror::Object* obj,
uintptr_t* out_rb_ptr_high_bits)
SHARED_REQUIRES(Locks::mutator_lock_);
// Note: These couldn't be constexpr pointers as reinterpret_cast isn't compatible with them.
static constexpr uintptr_t white_ptr_ = 0x0; // Not marked.
static constexpr uintptr_t gray_ptr_ = 0x1; // Marked, but not marked through. On mark stack.
// TODO: black_ptr_ is unused, we should remove it.
static constexpr uintptr_t black_ptr_ = 0x2; // Marked through. Used for non-moving objects.
static constexpr uintptr_t rb_ptr_mask_ = 0x1; // The low bits for white|gray.
};
} // namespace art
#endif // ART_RUNTIME_READ_BARRIER_H_