/usr/include/boost/atomic/detail
Edit: /usr/include/boost/atomic/detail/gcc_atomic_memory_order_utils.hpp (2804B)
/*
* 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) 2020 Andrey Semashev
*/
/*!
* \file atomic/detail/gcc_atomic_memory_order_utils.hpp
*
* This header contains utilities for working with gcc atomic memory order constants.
*/
#ifndef BOOST_ATOMIC_DETAIL_GCC_ATOMIC_MEMORY_ORDER_UTILS_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_GCC_ATOMIC_MEMORY_ORDER_UTILS_HPP_INCLUDED_
#include
#include
#include
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
namespace atomics {
namespace detail {
/*!
* The function converts \c boost::memory_order values to the compiler-specific constants.
*
* NOTE: The intention is that the function is optimized away by the compiler, and the
* compiler-specific constants are passed to the intrinsics. Unfortunately, constexpr doesn't
* work in this case because the standard atomics interface require memory ordering
* constants to be passed as function arguments, at which point they stop being constexpr.
* However, it is crucial that the compiler sees constants and not runtime values,
* because otherwise it just ignores the ordering value and always uses seq_cst.
* This is the case with Intel C++ Compiler 14.0.3 (Composer XE 2013 SP1, update 3) and
* gcc 4.8.2. Intel Compiler issues a warning in this case:
*
* warning #32013: Invalid memory order specified. Defaulting to seq_cst memory order.
*
* while gcc acts silently.
*
* To mitigate the problem ALL functions, including the atomic<> members must be
* declared with BOOST_FORCEINLINE. In this case the compilers are able to see that
* all functions are called with constant orderings and call intrinstcts properly.
*
* Unfortunately, this still doesn't work in debug mode as the compiler doesn't
* propagate constants even when functions are marked with BOOST_FORCEINLINE. In this case
* all atomic operaions will be executed with seq_cst semantics.
*/
BOOST_FORCEINLINE BOOST_CONSTEXPR int convert_memory_order_to_gcc(memory_order order) BOOST_NOEXCEPT
{
return (order == memory_order_relaxed ? __ATOMIC_RELAXED : (order == memory_order_consume ? __ATOMIC_CONSUME :
(order == memory_order_acquire ? __ATOMIC_ACQUIRE : (order == memory_order_release ? __ATOMIC_RELEASE :
(order == memory_order_acq_rel ? __ATOMIC_ACQ_REL : __ATOMIC_SEQ_CST)))));
}
} // namespace detail
} // namespace atomics
} // namespace boost
#include
#endif // BOOST_ATOMIC_DETAIL_GCC_ATOMIC_MEMORY_ORDER_UTILS_HPP_INCLUDED_