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()29 void 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)43 sys::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 
AtomicIncrement(volatile sys::cas_flag * ptr)60 sys::cas_flag sys::AtomicIncrement(volatile sys::cas_flag* ptr) {
61 #if LLVM_HAS_ATOMICS == 0
62   ++(*ptr);
63   return *ptr;
64 #elif defined(GNU_ATOMICS)
65   return __sync_add_and_fetch(ptr, 1);
66 #elif defined(_MSC_VER)
67   return InterlockedIncrement(ptr);
68 #else
69 #  error No atomic increment implementation for your platform!
70 #endif
71 }
72 
AtomicDecrement(volatile sys::cas_flag * ptr)73 sys::cas_flag sys::AtomicDecrement(volatile sys::cas_flag* ptr) {
74 #if LLVM_HAS_ATOMICS == 0
75   --(*ptr);
76   return *ptr;
77 #elif defined(GNU_ATOMICS)
78   return __sync_sub_and_fetch(ptr, 1);
79 #elif defined(_MSC_VER)
80   return InterlockedDecrement(ptr);
81 #else
82 #  error No atomic decrement implementation for your platform!
83 #endif
84 }
85 
AtomicAdd(volatile sys::cas_flag * ptr,sys::cas_flag val)86 sys::cas_flag sys::AtomicAdd(volatile sys::cas_flag* ptr, sys::cas_flag val) {
87 #if LLVM_HAS_ATOMICS == 0
88   *ptr += val;
89   return *ptr;
90 #elif defined(GNU_ATOMICS)
91   return __sync_add_and_fetch(ptr, val);
92 #elif defined(_MSC_VER)
93   return InterlockedExchangeAdd(ptr, val) + val;
94 #else
95 #  error No atomic add implementation for your platform!
96 #endif
97 }
98 
AtomicMul(volatile sys::cas_flag * ptr,sys::cas_flag val)99 sys::cas_flag sys::AtomicMul(volatile sys::cas_flag* ptr, sys::cas_flag val) {
100   sys::cas_flag original, result;
101   do {
102     original = *ptr;
103     result = original * val;
104   } while (sys::CompareAndSwap(ptr, result, original) != original);
105 
106   return result;
107 }
108 
AtomicDiv(volatile sys::cas_flag * ptr,sys::cas_flag val)109 sys::cas_flag sys::AtomicDiv(volatile sys::cas_flag* ptr, sys::cas_flag val) {
110   sys::cas_flag original, result;
111   do {
112     original = *ptr;
113     result = original / val;
114   } while (sys::CompareAndSwap(ptr, result, original) != original);
115 
116   return result;
117 }
118