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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) 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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