src/hotspot/os_cpu/linux_zero/atomic_linux_zero.hpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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#ifndef OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP
#define OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP

#include "orderAccess_linux_zero.hpp"

// Implementation of class atomic

template<size_t byte_size>
struct Atomic::PlatformAdd {
  template<typename D, typename I>
  D add_then_fetch(D volatile* dest, I add_value, atomic_memory_order order) const;

  template<typename D, typename I>
  D fetch_then_add(D volatile* dest, I add_value, atomic_memory_order order) const {
    return add_then_fetch(dest, add_value, order) - add_value;
  }
};

template<>
template<typename D, typename I>
inline D Atomic::PlatformAdd<4>::add_then_fetch(D volatile* dest, I add_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(I));
  STATIC_ASSERT(4 == sizeof(D));

  D res = __atomic_add_fetch(dest, add_value, __ATOMIC_RELEASE);
  FULL_MEM_BARRIER;
  return res;
}

template<>
template<typename D, typename I>
inline D Atomic::PlatformAdd<8>::add_then_fetch(D volatile* dest, I add_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(I));
  STATIC_ASSERT(8 == sizeof(D));

  D res = __atomic_add_fetch(dest, add_value, __ATOMIC_RELEASE);
  FULL_MEM_BARRIER;
  return res;
}

template<>
template<typename T>
inline T Atomic::PlatformXchg<4>::operator()(T volatile* dest,
                                             T exchange_value,
                                             atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(T));
  FULL_MEM_BARRIER;
  T result = __atomic_exchange_n(dest, exchange_value, __ATOMIC_RELAXED);
  FULL_MEM_BARRIER;
  return result;
}

template<>
template<typename T>
inline T Atomic::PlatformXchg<8>::operator()(T volatile* dest,
                                             T exchange_value,
                                             atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(T));
  FULL_MEM_BARRIER;
  T result = __atomic_exchange_n(dest, exchange_value, __ATOMIC_RELAXED);
  FULL_MEM_BARRIER;
  return result;
}

// No direct support for cmpxchg of bytes; emulate using int.
template<>
struct Atomic::PlatformCmpxchg<1> : Atomic::CmpxchgByteUsingInt {};

template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<4>::operator()(T volatile* dest,
                                                T compare_value,
                                                T exchange_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(T));

  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<>
template<typename T>
inline T Atomic::PlatformCmpxchg<8>::operator()(T volatile* dest,
                                                T compare_value,
                                                T exchange_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(T));

  FULL_MEM_BARRIER;
  T value = compare_value;
  __atomic_compare_exchange(dest, &value, &exchange_value, /*weak*/false,
                            __ATOMIC_RELAXED, __ATOMIC_RELAXED);
  FULL_MEM_BARRIER;
  return value;
}

// Atomically copy 64 bits of data
inline void atomic_copy64(const volatile void *src, volatile void *dst) {
  int64_t tmp;
  __atomic_load(reinterpret_cast<const volatile int64_t*>(src), &tmp, __ATOMIC_RELAXED);
  __atomic_store(reinterpret_cast<volatile int64_t*>(dst), &tmp, __ATOMIC_RELAXED);
}

template<>
template<typename T>
inline T Atomic::PlatformLoad<8>::operator()(T const volatile* src) const {
  STATIC_ASSERT(8 == sizeof(T));
  T dest;
  __atomic_load(const_cast<T*>(src), &dest, __ATOMIC_RELAXED);
  return dest;
}

template<>
template<typename T>
inline void Atomic::PlatformStore<8>::operator()(T volatile* dest,
                                                 T store_value) const {
  STATIC_ASSERT(8 == sizeof(T));
  __atomic_store(dest, &store_value, __ATOMIC_RELAXED);
}

#endif // OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP