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Filename : core_ops_gcc_atomic.hpp
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/*
 * 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) 2014, 2020 Andrey Semashev
 */
/*!
 * \file   atomic/detail/core_ops_gcc_atomic.hpp
 *
 * This header contains implementation of the \c core_operations template.
 */

#ifndef BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_ATOMIC_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_ATOMIC_HPP_INCLUDED_

#include <cstddef>
#include <boost/memory_order.hpp>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/storage_traits.hpp>
#include <boost/atomic/detail/core_operations_fwd.hpp>
#include <boost/atomic/detail/core_arch_operations.hpp>
#include <boost/atomic/detail/capabilities.hpp>
#include <boost/atomic/detail/gcc_atomic_memory_order_utils.hpp>

#if BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT8_LOCK_FREE < BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT16_LOCK_FREE || BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT16_LOCK_FREE < BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT32_LOCK_FREE ||\
    BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT32_LOCK_FREE < BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE || BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE < BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE
// There are platforms where we need to use larger storage types
#include <boost/atomic/detail/int_sizes.hpp>
#include <boost/atomic/detail/extending_cas_based_arithmetic.hpp>
#endif
#include <boost/atomic/detail/header.hpp>

#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif

#if defined(__INTEL_COMPILER)
// This is used to suppress warning #32013 described in gcc_atomic_memory_order_utils.hpp
// for Intel Compiler.
// In debug builds the compiler does not inline any functions, so basically
// every atomic function call results in this warning. I don't know any other
// way to selectively disable just this one warning.
#pragma system_header
#endif

namespace boost {
namespace atomics {
namespace detail {

template< std::size_t Size, bool Signed, bool Interprocess >
struct core_operations_gcc_atomic
{
    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< Size >::alignment;
    static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;
    static BOOST_CONSTEXPR_OR_CONST bool is_interprocess = Interprocess;
    static BOOST_CONSTEXPR_OR_CONST bool full_cas_based = false;

    // Note: In the current implementation, core_operations_gcc_atomic are used only when the particularly sized __atomic
    // intrinsics are always lock-free (i.e. the corresponding LOCK_FREE macro is 2). Therefore it is safe to
    // always set is_always_lock_free to true here.
    static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;

    static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
#if defined(BOOST_GCC) && BOOST_GCC < 100100 && (defined(__x86_64__) || defined(__i386__))
        // gcc up to 10.1 generates mov + mfence for seq_cst stores, which is slower than xchg
        if (order != memory_order_seq_cst)
            __atomic_store_n(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
        else
            __atomic_exchange_n(&storage, v, __ATOMIC_SEQ_CST);
#else
        __atomic_store_n(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
#endif
    }

    static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
#if defined(BOOST_ATOMIC_DETAIL_AARCH64_HAS_RCPC)
        // At least gcc 9.3 and clang 10 do not generate relaxed ldapr instructions that are available in ARMv8.3-RCPC extension.
        // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95751
        typedef atomics::detail::core_arch_operations< storage_size, is_signed, is_interprocess > core_arch_operations;
        return core_arch_operations::load(storage, order);
#else
        return __atomic_load_n(&storage, atomics::detail::convert_memory_order_to_gcc(order));
#endif
    }

    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_fetch_add(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_fetch_sub(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_exchange_n(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE bool compare_exchange_strong(
        storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
    {
        return __atomic_compare_exchange_n
        (
            &storage, &expected, desired, false,
            atomics::detail::convert_memory_order_to_gcc(success_order),
            atomics::detail::convert_memory_order_to_gcc(failure_order)
        );
    }

    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 __atomic_compare_exchange_n
        (
            &storage, &expected, desired, true,
            atomics::detail::convert_memory_order_to_gcc(success_order),
            atomics::detail::convert_memory_order_to_gcc(failure_order)
        );
    }

    static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_fetch_and(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_fetch_or(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_fetch_xor(&storage, v, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
        return __atomic_test_and_set(&storage, atomics::detail::convert_memory_order_to_gcc(order));
    }

    static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
    {
        __atomic_clear(const_cast< storage_type* >(&storage), atomics::detail::convert_memory_order_to_gcc(order));
    }
};

// We want to only enable __atomic* intrinsics when the corresponding BOOST_ATOMIC_DETAIL_GCC_ATOMIC_*_LOCK_FREE macro indicates
// the same or better lock-free guarantees as the BOOST_ATOMIC_*_LOCK_FREE macro. Otherwise, we want to leave core_operations
// unspecialized, so that core_arch_operations is used instead.

#if BOOST_ATOMIC_INT128_LOCK_FREE > 0 && BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE >= BOOST_ATOMIC_INT128_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 16u, Signed, Interprocess > :
    public core_operations_gcc_atomic< 16u, Signed, Interprocess >
{
};

#endif

#if BOOST_ATOMIC_INT64_LOCK_FREE > 0
#if BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE >= BOOST_ATOMIC_INT64_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 8u, Signed, Interprocess > :
    public core_operations_gcc_atomic< 8u, Signed, Interprocess >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE >= BOOST_ATOMIC_INT64_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 8u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 16u, Signed, Interprocess >, 8u, Signed >
{
};

#endif
#endif // BOOST_ATOMIC_INT64_LOCK_FREE > 0


#if BOOST_ATOMIC_INT32_LOCK_FREE > 0
#if BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT32_LOCK_FREE >= BOOST_ATOMIC_INT32_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 4u, Signed, Interprocess > :
    public core_operations_gcc_atomic< 4u, Signed, Interprocess >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE >= BOOST_ATOMIC_INT32_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 4u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 8u, Signed, Interprocess >, 4u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE >= BOOST_ATOMIC_INT32_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 8u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 16u, Signed, Interprocess >, 4u, Signed >
{
};

#endif
#endif // BOOST_ATOMIC_INT32_LOCK_FREE > 0


#if BOOST_ATOMIC_INT16_LOCK_FREE > 0
#if BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT16_LOCK_FREE >= BOOST_ATOMIC_INT16_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 2u, Signed, Interprocess > :
    public core_operations_gcc_atomic< 2u, Signed, Interprocess >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT32_LOCK_FREE >= BOOST_ATOMIC_INT16_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 2u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 4u, Signed, Interprocess >, 2u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE >= BOOST_ATOMIC_INT16_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 2u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 8u, Signed, Interprocess >, 2u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE >= BOOST_ATOMIC_INT16_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 2u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 16u, Signed, Interprocess >, 2u, Signed >
{
};

#endif
#endif // BOOST_ATOMIC_INT16_LOCK_FREE > 0


#if BOOST_ATOMIC_INT8_LOCK_FREE > 0
#if BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT8_LOCK_FREE >= BOOST_ATOMIC_INT8_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
    public core_operations_gcc_atomic< 1u, Signed, Interprocess >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT16_LOCK_FREE >= BOOST_ATOMIC_INT8_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 2u, Signed, Interprocess >, 1u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT32_LOCK_FREE >= BOOST_ATOMIC_INT8_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 4u, Signed, Interprocess >, 1u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT64_LOCK_FREE >= BOOST_ATOMIC_INT8_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 8u, Signed, Interprocess >, 1u, Signed >
{
};

#elif BOOST_ATOMIC_DETAIL_GCC_ATOMIC_INT128_LOCK_FREE >= BOOST_ATOMIC_INT8_LOCK_FREE

template< bool Signed, bool Interprocess >
struct core_operations< 1u, Signed, Interprocess > :
    public extending_cas_based_arithmetic< core_operations_gcc_atomic< 16u, Signed, Interprocess >, 1u, Signed >
{
};

#endif
#endif // BOOST_ATOMIC_INT8_LOCK_FREE > 0

} // namespace detail
} // namespace atomics
} // namespace boost

#include <boost/atomic/detail/footer.hpp>

#endif // BOOST_ATOMIC_DETAIL_CORE_OPS_GCC_ATOMIC_HPP_INCLUDED_