60 lines · cpp
1//===-- Atomic.cpp - Atomic Operations --------------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements atomic operations.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/Support/Atomic.h"14#include "llvm/Config/llvm-config.h"15 16using namespace llvm;17 18#if defined(_MSC_VER)19#include <intrin.h>20 21// We must include windows.h after intrin.h.22#include <windows.h>23#undef MemoryFence24#endif25 26#if defined(__GNUC__) || (defined(__IBMCPP__) && __IBMCPP__ >= 1210)27#define GNU_ATOMICS28#endif29 30void sys::MemoryFence() {31#if LLVM_HAS_ATOMICS == 032 return;33#else34# if defined(GNU_ATOMICS)35 __sync_synchronize();36# elif defined(_MSC_VER)37 MemoryBarrier();38# else39# error No memory fence implementation for your platform!40# endif41#endif42}43 44sys::cas_flag sys::CompareAndSwap(volatile sys::cas_flag* ptr,45 sys::cas_flag new_value,46 sys::cas_flag old_value) {47#if LLVM_HAS_ATOMICS == 048 sys::cas_flag result = *ptr;49 if (result == old_value)50 *ptr = new_value;51 return result;52#elif defined(GNU_ATOMICS)53 return __sync_val_compare_and_swap(ptr, old_value, new_value);54#elif defined(_MSC_VER)55 return InterlockedCompareExchange(ptr, new_value, old_value);56#else57# error No compare-and-swap implementation for your platform!58#endif59}60