/usr/include/boost/atomic/detail
Edit: /usr/include/boost/atomic/detail/core_ops_gcc_sync.hpp (10690B)
/*
* 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/core_ops_gcc_sync.hpp
*
* This header contains implementation of the \c core_operations template.
*/
#ifndef BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_SYNC_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_SYNC_HPP_INCLUDED_
#include
#include
#include
#include
#include
#include
#include
#include
#include
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
namespace atomics {
namespace detail {
struct core_operations_gcc_sync_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, bool Interprocess >
struct core_operations_gcc_sync :
public core_operations_gcc_sync_base
{
typedef typename storage_traits< Size >::type storage_type;
static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = Size;
static BOOST_CONSTEXPR_OR_CONST std::size_t storage_alignment = storage_traits< storage_size >::alignment;
static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;
static BOOST_CONSTEXPR_OR_CONST bool is_interprocess = Interprocess;
// In general, we cannot guarantee atomicity of plain loads and stores of anything larger than a single byte on
// an arbitrary CPU architecture. However, all modern architectures seem to guarantee atomic loads and stores of
// suitably aligned objects of up to a pointer size. For larger objects we should probably use intrinsics to guarantee
// atomicity. If there appears an architecture where this doesn't hold, this threshold needs to be updated (patches are welcome).
typedef atomics::detail::integral_constant< bool, storage_size <= sizeof(void*) > plain_stores_loads_are_atomic;
static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
{
store(storage, v, order, plain_stores_loads_are_atomic());
}
static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order, atomics::detail::true_type) BOOST_NOEXCEPT
{
fence_before_store(order);
storage = v;
fence_after_store(order);
}
static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order, atomics::detail::false_type) BOOST_NOEXCEPT
{
exchange(storage, v, order);
}
static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT
{
return load(storage, order, plain_stores_loads_are_atomic());
}
static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order, atomics::detail::true_type) BOOST_NOEXCEPT
{
storage_type v = storage;
fence_after_load(order);
return v;
}
static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order, atomics::detail::false_type) BOOST_NOEXCEPT
{
// Note: don't use fetch_add or other arithmetics here since storage_type may not be an arithmetic type.
storage_type expected = storage_type();
storage_type desired = expected;
// We don't care if CAS succeeds or not. If it does, it will just write the same value there was before.
return __sync_val_compare_and_swap(const_cast< storage_type volatile* >(&storage), expected, desired);
}
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, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1)
public core_operations_gcc_sync< 1u, Signed, Interprocess >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 2u, Signed, Interprocess >, 1u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 4u, Signed, Interprocess >, 1u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 8u, Signed, Interprocess >, 1u, Signed >
#else
public extending_cas_based_arithmetic< core_operations_gcc_sync< 16u, Signed, Interprocess >, 1u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT16_LOCK_FREE > 0
template< bool Signed, bool Interprocess >
struct core_operations< 2u, Signed, Interprocess > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)
public core_operations_gcc_sync< 2u, Signed, Interprocess >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 4u, Signed, Interprocess >, 2u, Signed >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 8u, Signed, Interprocess >, 2u, Signed >
#else
public extending_cas_based_arithmetic< core_operations_gcc_sync< 16u, Signed, Interprocess >, 2u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT32_LOCK_FREE > 0
template< bool Signed, bool Interprocess >
struct core_operations< 4u, Signed, Interprocess > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
public core_operations_gcc_sync< 4u, Signed, Interprocess >
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public extending_cas_based_arithmetic< core_operations_gcc_sync< 8u, Signed, Interprocess >, 4u, Signed >
#else
public extending_cas_based_arithmetic< core_operations_gcc_sync< 16u, Signed, Interprocess >, 4u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT64_LOCK_FREE > 0
template< bool Signed, bool Interprocess >
struct core_operations< 8u, Signed, Interprocess > :
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
public core_operations_gcc_sync< 8u, Signed, Interprocess >
#else
public extending_cas_based_arithmetic< core_operations_gcc_sync< 16u, Signed, Interprocess >, 8u, Signed >
#endif
{
};
#endif
#if BOOST_ATOMIC_INT128_LOCK_FREE > 0
template< bool Signed, bool Interprocess >
struct core_operations< 16u, Signed, Interprocess > :
public core_operations_gcc_sync< 16u, Signed, Interprocess >
{
};
#endif
} // namespace detail
} // namespace atomics
} // namespace boost
#include
#endif // BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_SYNC_HPP_INCLUDED_