257 lines
9.6 KiB
C++
257 lines
9.6 KiB
C++
/*
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* Copyright (C) 2011 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_READBARRIER_INL_H_
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#define ART_RUNTIME_MIRROR_OBJECT_READBARRIER_INL_H_
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#include "object.h"
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#include "atomic.h"
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#include "lock_word-inl.h"
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#include "object_reference-inl.h"
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#include "read_barrier.h"
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#include "runtime.h"
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namespace art {
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namespace mirror {
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template<VerifyObjectFlags kVerifyFlags>
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inline LockWord Object::GetLockWord(bool as_volatile) {
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if (as_volatile) {
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return LockWord(GetField32Volatile<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Object, monitor_)));
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}
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return LockWord(GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Object, monitor_)));
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}
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template<bool kTransactionActive, bool kCheckTransaction, VerifyObjectFlags kVerifyFlags>
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inline bool Object::CasFieldWeakRelaxed32(MemberOffset field_offset,
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int32_t old_value, int32_t new_value) {
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if (kCheckTransaction) {
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DCHECK_EQ(kTransactionActive, Runtime::Current()->IsActiveTransaction());
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}
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if (kTransactionActive) {
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Runtime::Current()->RecordWriteField32(this, field_offset, old_value, true);
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}
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if (kVerifyFlags & kVerifyThis) {
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VerifyObject(this);
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}
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uint8_t* raw_addr = reinterpret_cast<uint8_t*>(this) + field_offset.Int32Value();
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AtomicInteger* atomic_addr = reinterpret_cast<AtomicInteger*>(raw_addr);
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return atomic_addr->CompareExchangeWeakRelaxed(old_value, new_value);
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}
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inline bool Object::CasLockWordWeakRelaxed(LockWord old_val, LockWord new_val) {
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// Force use of non-transactional mode and do not check.
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return CasFieldWeakRelaxed32<false, false>(
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OFFSET_OF_OBJECT_MEMBER(Object, monitor_), old_val.GetValue(), new_val.GetValue());
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}
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inline bool Object::CasLockWordWeakRelease(LockWord old_val, LockWord new_val) {
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// Force use of non-transactional mode and do not check.
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return CasFieldWeakRelease32<false, false>(
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OFFSET_OF_OBJECT_MEMBER(Object, monitor_), old_val.GetValue(), new_val.GetValue());
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}
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inline uint32_t Object::GetReadBarrierState(uintptr_t* fake_address_dependency) {
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if (!kUseBakerReadBarrier) {
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LOG(FATAL) << "Unreachable";
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UNREACHABLE();
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}
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#if defined(__arm__)
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uintptr_t obj = reinterpret_cast<uintptr_t>(this);
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uintptr_t result;
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DCHECK_EQ(OFFSETOF_MEMBER(Object, monitor_), 4U);
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// Use inline assembly to prevent the compiler from optimizing away the false dependency.
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__asm__ __volatile__(
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"ldr %[result], [%[obj], #4]\n\t"
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// This instruction is enough to "fool the compiler and the CPU" by having `fad` always be
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// null, without them being able to assume that fact.
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"eor %[fad], %[result], %[result]\n\t"
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: [result] "+r" (result), [fad] "=r" (*fake_address_dependency)
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: [obj] "r" (obj));
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DCHECK_EQ(*fake_address_dependency, 0U);
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LockWord lw(static_cast<uint32_t>(result));
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uint32_t rb_state = lw.ReadBarrierState();
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return rb_state;
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#elif defined(__aarch64__)
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uintptr_t obj = reinterpret_cast<uintptr_t>(this);
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uintptr_t result;
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DCHECK_EQ(OFFSETOF_MEMBER(Object, monitor_), 4U);
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// Use inline assembly to prevent the compiler from optimizing away the false dependency.
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__asm__ __volatile__(
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"ldr %w[result], [%[obj], #4]\n\t"
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// This instruction is enough to "fool the compiler and the CPU" by having `fad` always be
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// null, without them being able to assume that fact.
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"eor %[fad], %[result], %[result]\n\t"
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: [result] "+r" (result), [fad] "=r" (*fake_address_dependency)
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: [obj] "r" (obj));
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DCHECK_EQ(*fake_address_dependency, 0U);
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LockWord lw(static_cast<uint32_t>(result));
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uint32_t rb_state = lw.ReadBarrierState();
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return rb_state;
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#elif defined(__i386__) || defined(__x86_64__)
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LockWord lw = GetLockWord(false);
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// i386/x86_64 don't need fake address dependency. Use a compiler fence to avoid compiler
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// reordering.
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*fake_address_dependency = 0;
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std::atomic_signal_fence(std::memory_order_acquire);
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uint32_t rb_state = lw.ReadBarrierState();
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return rb_state;
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#else
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// MIPS32/MIPS64: use a memory barrier to prevent load-load reordering.
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LockWord lw = GetLockWord(false);
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*fake_address_dependency = 0;
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std::atomic_thread_fence(std::memory_order_acquire);
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uint32_t rb_state = lw.ReadBarrierState();
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return rb_state;
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#endif
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}
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inline uint32_t Object::GetReadBarrierState() {
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if (!kUseBakerReadBarrier) {
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LOG(FATAL) << "Unreachable";
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UNREACHABLE();
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}
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DCHECK(kUseBakerReadBarrier);
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LockWord lw(GetField<uint32_t, /*kIsVolatile*/false>(OFFSET_OF_OBJECT_MEMBER(Object, monitor_)));
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uint32_t rb_state = lw.ReadBarrierState();
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DCHECK(ReadBarrier::IsValidReadBarrierState(rb_state)) << rb_state;
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return rb_state;
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}
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inline uint32_t Object::GetReadBarrierStateAcquire() {
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if (!kUseBakerReadBarrier) {
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LOG(FATAL) << "Unreachable";
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UNREACHABLE();
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}
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LockWord lw(GetFieldAcquire<uint32_t>(OFFSET_OF_OBJECT_MEMBER(Object, monitor_)));
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uint32_t rb_state = lw.ReadBarrierState();
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DCHECK(ReadBarrier::IsValidReadBarrierState(rb_state)) << rb_state;
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return rb_state;
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}
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template<bool kCasRelease>
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inline bool Object::AtomicSetReadBarrierState(uint32_t expected_rb_state, uint32_t rb_state) {
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if (!kUseBakerReadBarrier) {
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LOG(FATAL) << "Unreachable";
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UNREACHABLE();
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}
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DCHECK(ReadBarrier::IsValidReadBarrierState(expected_rb_state)) << expected_rb_state;
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DCHECK(ReadBarrier::IsValidReadBarrierState(rb_state)) << rb_state;
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LockWord expected_lw;
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LockWord new_lw;
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do {
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LockWord lw = GetLockWord(false);
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if (UNLIKELY(lw.ReadBarrierState() != expected_rb_state)) {
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// Lost the race.
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return false;
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}
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expected_lw = lw;
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expected_lw.SetReadBarrierState(expected_rb_state);
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new_lw = lw;
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new_lw.SetReadBarrierState(rb_state);
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// ConcurrentCopying::ProcessMarkStackRef uses this with kCasRelease == true.
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// If kCasRelease == true, use a CAS release so that when GC updates all the fields of
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// an object and then changes the object from gray to black, the field updates (stores) will be
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// visible (won't be reordered after this CAS.)
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} while (!(kCasRelease ?
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CasLockWordWeakRelease(expected_lw, new_lw) :
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CasLockWordWeakRelaxed(expected_lw, new_lw)));
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return true;
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}
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inline bool Object::AtomicSetMarkBit(uint32_t expected_mark_bit, uint32_t mark_bit) {
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LockWord expected_lw;
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LockWord new_lw;
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do {
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LockWord lw = GetLockWord(false);
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if (UNLIKELY(lw.MarkBitState() != expected_mark_bit)) {
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// Lost the race.
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return false;
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}
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expected_lw = lw;
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new_lw = lw;
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new_lw.SetMarkBitState(mark_bit);
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// Since this is only set from the mutator, we can use the non release Cas.
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} while (!CasLockWordWeakRelaxed(expected_lw, new_lw));
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return true;
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}
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template<bool kTransactionActive, bool kCheckTransaction, VerifyObjectFlags kVerifyFlags>
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inline bool Object::CasFieldStrongRelaxedObjectWithoutWriteBarrier(
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MemberOffset field_offset,
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ObjPtr<Object> old_value,
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ObjPtr<Object> new_value) {
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if (kCheckTransaction) {
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DCHECK_EQ(kTransactionActive, Runtime::Current()->IsActiveTransaction());
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}
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if (kVerifyFlags & kVerifyThis) {
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VerifyObject(this);
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}
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if (kVerifyFlags & kVerifyWrites) {
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VerifyObject(new_value);
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}
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if (kVerifyFlags & kVerifyReads) {
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VerifyObject(old_value);
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}
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if (kTransactionActive) {
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Runtime::Current()->RecordWriteFieldReference(this, field_offset, old_value, true);
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}
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HeapReference<Object> old_ref(HeapReference<Object>::FromObjPtr(old_value));
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HeapReference<Object> new_ref(HeapReference<Object>::FromObjPtr(new_value));
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uint8_t* raw_addr = reinterpret_cast<uint8_t*>(this) + field_offset.Int32Value();
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Atomic<uint32_t>* atomic_addr = reinterpret_cast<Atomic<uint32_t>*>(raw_addr);
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bool success = atomic_addr->CompareExchangeStrongRelaxed(old_ref.reference_,
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new_ref.reference_);
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return success;
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}
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template<bool kTransactionActive, bool kCheckTransaction, VerifyObjectFlags kVerifyFlags>
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inline bool Object::CasFieldStrongReleaseObjectWithoutWriteBarrier(
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MemberOffset field_offset,
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ObjPtr<Object> old_value,
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ObjPtr<Object> new_value) {
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if (kCheckTransaction) {
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DCHECK_EQ(kTransactionActive, Runtime::Current()->IsActiveTransaction());
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}
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if (kVerifyFlags & kVerifyThis) {
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VerifyObject(this);
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}
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if (kVerifyFlags & kVerifyWrites) {
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VerifyObject(new_value);
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}
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if (kVerifyFlags & kVerifyReads) {
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VerifyObject(old_value);
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}
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if (kTransactionActive) {
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Runtime::Current()->RecordWriteFieldReference(this, field_offset, old_value, true);
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}
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HeapReference<Object> old_ref(HeapReference<Object>::FromObjPtr(old_value));
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HeapReference<Object> new_ref(HeapReference<Object>::FromObjPtr(new_value));
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uint8_t* raw_addr = reinterpret_cast<uint8_t*>(this) + field_offset.Int32Value();
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Atomic<uint32_t>* atomic_addr = reinterpret_cast<Atomic<uint32_t>*>(raw_addr);
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bool success = atomic_addr->CompareExchangeStrongRelease(old_ref.reference_,
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new_ref.reference_);
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return success;
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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_READBARRIER_INL_H_
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