LLVM  4.0.0
Atomic.cpp
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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 
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 
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 }
cas_flag CompareAndSwap(volatile cas_flag *ptr, cas_flag new_value, cas_flag old_value)
void MemoryFence()
Definition: Atomic.cpp:29