lib/System/Atomic.cpp

   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 header file implements atomic operations.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/System/Atomic.h"
  15 #include "llvm/Config/config.h"
  16
  17 using namespace llvm;
  18
  19 #if defined(_MSC_VER)
  20 #include <windows.h>
  21 #undef MemoryFence
  22 #endif
  23
  24 void sys::MemoryFence() {
  25 #if LLVM_MULTITHREADED==0
  26   return;
  27 #else
  28 #  if defined(__GNUC__)
  29   __sync_synchronize();
  30 #  elif defined(_MSC_VER)
  31   MemoryBarrier();
  32 #  else
  33 # error No memory fence implementation for your platform!
  34 #  endif
  35 #endif
  36 }
  37
  38 sys::cas_flag sys::CompareAndSwap(volatile sys::cas_flag* ptr,
  39                                   sys::cas_flag new_value,
  40                                   sys::cas_flag old_value) {
  41 #if LLVM_MULTITHREADED==0
  42   sys::cas_flag result = *ptr;
  43   if (result == old_value)
  44     *ptr = new_value;
  45   return result;
  46 #elif defined(__GNUC__)
  47   return __sync_val_compare_and_swap(ptr, old_value, new_value);
  48 #elif defined(_MSC_VER)
  49   return InterlockedCompareExchange(ptr, new_value, old_value);
  50 #else
  51 #  error No compare-and-swap implementation for your platform!
  52 #endif
  53 }
  54
  55 sys::cas_flag sys::AtomicIncrement(volatile sys::cas_flag* ptr) {
  56 #if LLVM_MULTITHREADED==0
  57   ++(*ptr);
  58   return *ptr;
  59 #elif defined(__GNUC__)
  60   return __sync_add_and_fetch(ptr, 1);
  61 #elif defined(_MSC_VER)
  62   return InterlockedIncrement(ptr);
  63 #else
  64 #  error No atomic increment implementation for your platform!
  65 #endif
  66 }
  67
  68 sys::cas_flag sys::AtomicDecrement(volatile sys::cas_flag* ptr) {
  69 #if LLVM_MULTITHREADED==0
  70   --(*ptr);
  71   return *ptr;
  72 #elif defined(__GNUC__)
  73   return __sync_sub_and_fetch(ptr, 1);
  74 #elif defined(_MSC_VER)
  75   return InterlockedDecrement(ptr);
  76 #else
  77 #  error No atomic decrement implementation for your platform!
  78 #endif
  79 }
  80
  81 sys::cas_flag sys::AtomicAdd(volatile sys::cas_flag* ptr, sys::cas_flag val) {
  82 #if LLVM_MULTITHREADED==0
  83   *ptr += val;
  84   return *ptr;
  85 #elif defined(__GNUC__)
  86   return __sync_add_and_fetch(ptr, val);
  87 #elif defined(_MSC_VER)
  88   return InterlockedExchangeAdd(ptr, val) + val;
  89 #else
  90 #  error No atomic add implementation for your platform!
  91 #endif
  92 }
  93
  94 sys::cas_flag sys::AtomicMul(volatile sys::cas_flag* ptr, sys::cas_flag val) {
  95   sys::cas_flag original, result;
  96   do {
  97     original = *ptr;
  98     result = original * val;
  99   } while (sys::CompareAndSwap(ptr, result, original) != original);
 100
 101   return result;
 102 }
 103
 104 sys::cas_flag sys::AtomicDiv(volatile sys::cas_flag* ptr, sys::cas_flag val) {
 105   sys::cas_flag original, result;
 106   do {
 107     original = *ptr;
 108     result = original / val;
 109   } while (sys::CompareAndSwap(ptr, result, original) != original);
 110
 111   return result;
 112 }