JDK14/Java14源码在线阅读

/*
 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2014, 2019, Red Hat Inc. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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#ifndef OS_CPU_LINUX_AARCH64_ATOMIC_LINUX_AARCH64_HPP
#define OS_CPU_LINUX_AARCH64_ATOMIC_LINUX_AARCH64_HPP

#include "runtime/vm_version.hpp"

// Implementation of class atomic
// Note that memory_order_conservative requires a full barrier after atomic stores.
// See https://patchwork.kernel.org/patch/3575821/

template<size_t byte_size>
struct Atomic::PlatformAdd
  : Atomic::AddAndFetch<Atomic::PlatformAdd<byte_size> >
{
  template<typename D, typename I>
  D add_and_fetch(D volatile* dest, I add_value, atomic_memory_order order) const {
    D res = __atomic_add_fetch(dest, add_value, __ATOMIC_RELEASE);
    FULL_MEM_BARRIER;
    return res;
  }
};

template<size_t byte_size>
template<typename T>
inline T Atomic::PlatformXchg<byte_size>::operator()(T volatile* dest,
                                                     T exchange_value,
                                                     atomic_memory_order order) const {
  STATIC_ASSERT(byte_size == sizeof(T));
  T res = __atomic_exchange_n(dest, exchange_value, __ATOMIC_RELEASE);
  FULL_MEM_BARRIER;
  return res;
}

template<size_t byte_size>
template<typename T>
inline T Atomic::PlatformCmpxchg<byte_size>::operator()(T volatile* dest,
                                                        T compare_value,
                                                        T exchange_value,
                                                        atomic_memory_order order) const {
  STATIC_ASSERT(byte_size == sizeof(T));
  if (order == memory_order_relaxed) {
    T value = compare_value;
    __atomic_compare_exchange(dest, &value, &exchange_value, /*weak*/false,
                              __ATOMIC_RELAXED, __ATOMIC_RELAXED);
    return value;
  } else {
    T value = compare_value;
    FULL_MEM_BARRIER;
    __atomic_compare_exchange(dest, &value, &exchange_value, /*weak*/false,
                              __ATOMIC_RELAXED, __ATOMIC_RELAXED);
    FULL_MEM_BARRIER;
    return value;
  }
}

template<size_t byte_size>
struct Atomic::PlatformOrderedLoad<byte_size, X_ACQUIRE>
{
  template <typename T>
  T operator()(const volatile T* p) const { T data; __atomic_load(const_cast<T*>(p), &data, __ATOMIC_ACQUIRE); return data; }
};

template<size_t byte_size>
struct Atomic::PlatformOrderedStore<byte_size, RELEASE_X>
{

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