use_pointer.cpp

Go to the documentation of this file.

/*
 * Copyright 2021 MusicScience37 (Kenta Kabashima)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "stat_bench/do_not_optimize.h"
 
#if defined(__GNUC__) || defined(__clang__)
 
/* *****************************************************************
 * For GCC and Clang with inline assembly.
 * *****************************************************************/
 
namespace stat_bench {
namespace impl {
 
void use_pointer(void* ptr) noexcept {
    // NOLINTNEXTLINE
    asm volatile("" : : "g"(ptr) : "memory");
}
 
}  // namespace impl
}  // namespace stat_bench
 
#else
 
/* *****************************************************************
 * Fallback implementation using volatile.
 * *****************************************************************/
 
#include <atomic>
 
namespace stat_bench {
namespace impl {
 
void use_pointer(void* ptr) noexcept {
    std::atomic_signal_fence(std::memory_order_acq_rel);
    *reinterpret_cast<char volatile*>(ptr) =
        *reinterpret_cast<char volatile*>(ptr);
    std::atomic_signal_fence(std::memory_order_acq_rel);
}
 
}  // namespace impl
}  // namespace stat_bench
 
#endif