ecency-mobile/ios/Pods/Folly/folly/portability/Asm.h
2019-05-29 14:32:35 +03:00

65 lines
1.7 KiB
C++

/*
* Copyright 2016-present Facebook, Inc.
*
* 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.
*/
#pragma once
#include <folly/Portability.h>
#include <chrono>
#include <cstdint>
#ifdef _MSC_VER
#include <intrin.h>
#endif
namespace folly {
inline void asm_volatile_memory() {
#if defined(__clang__) || defined(__GNUC__)
asm volatile("" : : : "memory");
#elif defined(_MSC_VER)
::_ReadWriteBarrier();
#endif
}
inline void asm_volatile_pause() {
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
::_mm_pause();
#elif defined(__i386__) || FOLLY_X64
asm volatile("pause");
#elif FOLLY_AARCH64 || defined(__arm__)
asm volatile("yield");
#elif FOLLY_PPC64
asm volatile("or 27,27,27");
#endif
}
inline std::uint64_t asm_rdtsc() {
#if _MSC_VER
return (uint64_t)__rdtsc();
#elif defined(__i386__) || FOLLY_X64
// read the timestamp counter on x86
auto hi = std::uint32_t{};
auto lo = std::uint32_t{};
asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
return (((std::uint64_t)lo) + (((std::uint64_t)hi) << 32));
#else
// use steady_clock::now() as an approximation for the timestamp counter on
// non-x86 systems
return std::chrono::steady_clock::now().time_since_epoch().count();
#endif
}
} // namespace folly