1 //===- llvm/Support/Atomic.h - 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-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file declares the llvm::sys atomic operations.
10 //
11 // DO NOT USE IN NEW CODE!
12 //
13 // New code should always rely on the std::atomic facilities in C++11.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_SUPPORT_ATOMIC_H
18 #define LLVM_SUPPORT_ATOMIC_H
19 
20 #include "llvm/Support/DataTypes.h"
21 
22 // Windows will at times define MemoryFence.
23 #ifdef MemoryFence
24 #undef MemoryFence
25 #endif
26 
27 namespace llvm {
28   namespace sys {
29     void MemoryFence();
30 
31 #ifdef _MSC_VER
32     typedef long cas_flag;
33 #else
34     typedef uint32_t cas_flag;
35 #endif
36     cas_flag CompareAndSwap(volatile cas_flag* ptr,
37                             cas_flag new_value,
38                             cas_flag old_value);
39   }
40 }
41 
42 #endif
43