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      1 //===- llvm/Support/Atomic.h - 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 declares the llvm::sys atomic operations.
     11 //
     12 // DO NOT USE IN NEW CODE!
     13 //
     14 // New code should always rely on the std::atomic facilities in C++11.
     15 //
     16 //===----------------------------------------------------------------------===//
     17 
     18 #ifndef LLVM_SUPPORT_ATOMIC_H
     19 #define LLVM_SUPPORT_ATOMIC_H
     20 
     21 #include "llvm/Support/DataTypes.h"
     22 
     23 // Windows will at times define MemoryFence.
     24 #ifdef MemoryFence
     25 #undef MemoryFence
     26 #endif
     27 
     28 namespace llvm {
     29   namespace sys {
     30     void MemoryFence();
     31 
     32 #ifdef _MSC_VER
     33     typedef long cas_flag;
     34 #else
     35     typedef uint32_t cas_flag;
     36 #endif
     37     cas_flag CompareAndSwap(volatile cas_flag* ptr,
     38                             cas_flag new_value,
     39                             cas_flag old_value);
     40   }
     41 }
     42 
     43 #endif
     44