1 //===-- Atomic.cpp - Atomic Operations --------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements atomic operations. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Support/Atomic.h" 15 #include "llvm/Config/llvm-config.h" 16 17 using namespace llvm; 18 19 #if defined(_MSC_VER) 20 #include <Intrin.h> 21 #include <windows.h> 22 #undef MemoryFence 23 #endif 24 25 #if defined(__GNUC__) || (defined(__IBMCPP__) && __IBMCPP__ >= 1210) 26 #define GNU_ATOMICS 27 #endif 28 MemoryFence()29void sys::MemoryFence() { 30 #if LLVM_HAS_ATOMICS == 0 31 return; 32 #else 33 # if defined(GNU_ATOMICS) 34 __sync_synchronize(); 35 # elif defined(_MSC_VER) 36 MemoryBarrier(); 37 # else 38 # error No memory fence implementation for your platform! 39 # endif 40 #endif 41 } 42 CompareAndSwap(volatile sys::cas_flag * ptr,sys::cas_flag new_value,sys::cas_flag old_value)43sys::cas_flag sys::CompareAndSwap(volatile sys::cas_flag* ptr, 44 sys::cas_flag new_value, 45 sys::cas_flag old_value) { 46 #if LLVM_HAS_ATOMICS == 0 47 sys::cas_flag result = *ptr; 48 if (result == old_value) 49 *ptr = new_value; 50 return result; 51 #elif defined(GNU_ATOMICS) 52 return __sync_val_compare_and_swap(ptr, old_value, new_value); 53 #elif defined(_MSC_VER) 54 return InterlockedCompareExchange(ptr, new_value, old_value); 55 #else 56 # error No compare-and-swap implementation for your platform! 57 #endif 58 } 59