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Current File : //usr/include/boost/atomic/detail/ops_gcc_sync.hpp
/*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* Copyright (c) 2011 Helge Bahmann
* Copyright (c) 2013 Tim Blechmann
* Copyright (c) 2014 Andrey Semashev
*/
/*!
* \file atomic/detail/ops_gcc_sync.hpp
*
* This header contains implementation of the \c operations template.
*/
#ifndef BOOST_ATOMIC_DETAIL_OPS_GCC_SYNC_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_OPS_GCC_SYNC_HPP_INCLUDED_
#include <cstddef>
#include <boost/memory_order.hpp>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/storage_type.hpp>
#include <boost/atomic/detail/operations_fwd.hpp>
#include <boost/atomic/detail/ops_extending_cas_based.hpp>
#include <boost/atomic/capabilities.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
namespace atomics {
namespace detail {
struct gcc_sync_operations_base
{
static BOOST_CONSTEXPR_OR_CONST bool full_cas_based = false;
static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;
static BOOST_FORCEINLINE void fence_before_store(memory_order order) BOOST_NOEXCEPT
{
if ((static_cast< unsigned int >(order) & static_cast< unsigned int >(memory_order_release)) != 0u)
__sync_synchronize();
}
static BOOST_FORCEINLINE void fence_after_store(memory_order order) BOOST_NOEXCEPT
{
if (order == memory_order_seq_cst)
__sync_synchronize();
}
static BOOST_FORCEINLINE void fence_after_load(memory_order order) BOOST_NOEXCEPT
{
if ((static_cast< unsigned int >(order) & (static_cast< unsigned int >(memory_order_acquire) | static_cast< unsigned int >(memory_order_consume))) != 0u)
__sync_synchronize();
}
};
template< std::size_t Size, bool Signed >
struct gcc_sync_operations :
public gcc_sync_operations_base
{
typedef typename make_storage_type< Size >::type storage_type;
typedef typename make_storage_type< Size >::aligned aligned_storage_type;
static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = Size;
static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;
static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
{
fence_before_store(order);
storage = v;
fence_after_store(order);
}
static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT
{
storage_type v = storage;
fence_after_load(order);
return v;
}
static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
{
return __sync_fetch_and_add(&storage, v);
}
static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
{
return __sync_fetch_and_sub(&storage, v);
}
static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
{
// GCC docs mention that not all architectures may support full exchange semantics for this intrinsic. However, GCC's implementation of
// std::atomic<> uses this intrinsic unconditionally. We do so as well. In case if some architectures actually don't support this, we can always
// add a check here and fall back to a CAS loop.
if ((static_cast< unsigned int >(order) & static_cast< unsigned int >(memory_order_release)) != 0u)
__sync_synchronize();
return __sync_lock_test_and_set(&storage, v);
}
static BOOST_FORCEINLINE bool compare_exchange_strong(
storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order, memory_order) BOOST_NOEXCEPT
{
storage_type expected2 = expected;
storage_type old_val = __sync_val_compare_and_swap(&storage, expected2, desired);
if (old_val == expected2)
{
return true;
}
else
{
expected = old_val;
return false;
}
}
static BOOST_FORCEINLINE bool compare_exchange_weak(
storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
{
return compare_exchange_strong(storage, expected, desired, success_order, failure_order);
}
static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
{
return __sync_fetch_and_and(&storage, v);
}
static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
{
return __sync_fetch_and_or(&storage, v);
}
static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order) BOOST_NOEXCEPT
{
return __sync_fetch_and_xor(&storage, v);
}
static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
{
if ((static_cast< unsigned int >(order) & static_cast< unsigned int >(memory_order_release)) != 0u)
__sync_synchronize();
return !!__sync_lock_test_and_set(&storage, 1);
}
static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
{
__sync_lock_release(&storage);
if (order == memory_order_seq_cst)
__sync_synchronize();
}
};
#if BOOST_ATOMIC_INT8_LOCK_FREE > 0
template< bool Signed >
struct operations< 1u, Signed > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1)
public gcc_sync_operations< 1u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)
public extending_cas_based_operations< gcc_sync_operations< 2u, Signed >, 1u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public extending_cas_based_operations< gcc_sync_operations< 4u, Signed >, 1u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_operations< gcc_sync_operations< 8u, Signed >, 1u, Signed >
#else
public extending_cas_based_operations< gcc_sync_operations< 16u, Signed >, 1u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT16_LOCK_FREE > 0
template< bool Signed >
struct operations< 2u, Signed > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)
public gcc_sync_operations< 2u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public extending_cas_based_operations< gcc_sync_operations< 4u, Signed >, 2u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_operations< gcc_sync_operations< 8u, Signed >, 2u, Signed >
#else
public extending_cas_based_operations< gcc_sync_operations< 16u, Signed >, 2u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT32_LOCK_FREE > 0
template< bool Signed >
struct operations< 4u, Signed > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public gcc_sync_operations< 4u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_operations< gcc_sync_operations< 8u, Signed >, 4u, Signed >
#else
public extending_cas_based_operations< gcc_sync_operations< 16u, Signed >, 4u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT64_LOCK_FREE > 0
template< bool Signed >
struct operations< 8u, Signed > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public gcc_sync_operations< 8u, Signed >
#else
public extending_cas_based_operations< gcc_sync_operations< 16u, Signed >, 8u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT128_LOCK_FREE > 0
template< bool Signed >
struct operations< 16u, Signed > :
public gcc_sync_operations< 16u, Signed >
{
};
#endif
BOOST_FORCEINLINE void thread_fence(memory_order order) BOOST_NOEXCEPT
{
if (order != memory_order_relaxed)
__sync_synchronize();
}
BOOST_FORCEINLINE void signal_fence(memory_order order) BOOST_NOEXCEPT
{
if (order != memory_order_relaxed)
__asm__ __volatile__ ("" ::: "memory");
}
} // namespace detail
} // namespace atomics
} // namespace boost
#endif // BOOST_ATOMIC_DETAIL_OPS_GCC_SYNC_HPP_INCLUDED_
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