lib/System/Atomic.cpp

//===-- Atomic.cpp - Atomic Operations --------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This header file implements atomic operations.
//
//===----------------------------------------------------------------------===//

#include "llvm/System/Atomic.h"
#include "llvm/Config/config.h"

using namespace llvm;

#if defined(_MSC_VER)
#include <windows.h>
#undef MemoryFence
#endif

void sys::MemoryFence() {
#if LLVM_MULTITHREADED==0
  return;
#else
#  if defined(__GNUC__)
  __sync_synchronize();
#  elif defined(_MSC_VER)
  MemoryBarrier();
#  else
# error No memory fence implementation for your platform!
#  endif
#endif
}

uint32_t sys::CompareAndSwap32(volatile uint32_t* ptr,
                               uint32_t new_value,
                               uint32_t old_value) {
#if LLVM_MULTITHREADED==0
  uint32_t result = *ptr;
  if (result == old_value)
    *ptr = new_value;
  return result;
#elif defined(__GNUC__)
  return __sync_val_compare_and_swap(ptr, old_value, new_value);
#elif defined(_MSC_VER)
  return InterlockedCompareExchange(ptr, new_value, old_value);
#else
#  error No compare-and-swap implementation for your platform!
#endif
}

int32_t sys::AtomicIncrement32(volatile int32_t* ptr) {
#if LLVM_MULTITHREADED==0
  ++(*ptr);
  return *ptr;
#elif defined(__GNUC__)
  return __sync_add_and_fetch(ptr, 1);
#elif defined(_MSC_VER)
  return InterlockedIncrement(ptr);
#else
#  error No atomic increment implementation for your platform!
#endif
}

int32_t sys::AtomicDecrement32(volatile int32_t* ptr) {
#if LLVM_MULTITHREADED==0
  --(*ptr);
  return *ptr;
#elif defined(__GNUC__)
  return __sync_sub_and_fetch(ptr, 1);
#elif defined(_MSC_VER)
  return InterlockedDecrement(ptr);
#else
#  error No atomic decrement implementation for your platform!
#endif
}

int32_t sys::AtomicAdd32(volatile int32_t* ptr, int32_t val) {
#if LLVM_MULTITHREADED==0
  *ptr += val;
  return *ptr;
#elif defined(__GNUC__)
  return __sync_add_and_fetch(ptr, val);
#elif defined(_MSC_VER)
  return InterlockedAdd(ptr, val);
#else
#  error No atomic add implementation for your platform!
#endif
}

int64_t sys::AtomicAdd64(volatile int64_t* ptr, int64_t val) {
#if LLVM_MULTITHREADED==0
  *ptr += val;
  return *ptr;
#elif defined(__GNUC__)
  return __sync_add_and_fetch(ptr, val);
#elif defined(_MSC_VER)
  return InterlockedAdd64(ptr, val);
#else
#  error No atomic add implementation for your platform!
#endif
}