LLVM  6.0.0svn
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 
22 // We must include windows.h after intrin.h.
23 #include <windows.h>
24 #undef MemoryFence
25 #endif
26 
27 #if defined(__GNUC__) || (defined(__IBMCPP__) && __IBMCPP__ >= 1210)
28 #define GNU_ATOMICS
29 #endif
30 
32 #if LLVM_HAS_ATOMICS == 0
33  return;
34 #else
35 # if defined(GNU_ATOMICS)
36  __sync_synchronize();
37 # elif defined(_MSC_VER)
38  MemoryBarrier();
39 # else
40 # error No memory fence implementation for your platform!
41 # endif
42 #endif
43 }
44 
46  sys::cas_flag new_value,
47  sys::cas_flag old_value) {
48 #if LLVM_HAS_ATOMICS == 0
49  sys::cas_flag result = *ptr;
50  if (result == old_value)
51  *ptr = new_value;
52  return result;
53 #elif defined(GNU_ATOMICS)
54  return __sync_val_compare_and_swap(ptr, old_value, new_value);
55 #elif defined(_MSC_VER)
56  return InterlockedCompareExchange(ptr, new_value, old_value);
57 #else
58 # error No compare-and-swap implementation for your platform!
59 #endif
60 }
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
cas_flag CompareAndSwap(volatile cas_flag *ptr, cas_flag new_value, cas_flag old_value)
Definition: Atomic.cpp:45
void MemoryFence()
Definition: Atomic.cpp:31