llvm-mirror/lib/System/Threading.cpp

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//===-- llvm/System/Threading.cpp- Control multithreading mode --*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements llvm_start_multithreaded() and friends.
//
//===----------------------------------------------------------------------===//
#include "llvm/System/Threading.h"
#include "llvm/System/Atomic.h"
#include "llvm/System/Mutex.h"
#include <cassert>
using namespace llvm;
static bool multithreaded_mode = false;
static sys::Mutex* global_lock = 0;
bool llvm::llvm_start_multithreaded() {
#ifdef LLVM_MULTITHREADED
assert(!multithreaded_mode && "Already multithreaded!");
multithreaded_mode = true;
global_lock = new sys::Mutex(true);
// We fence here to ensure that all initialization is complete BEFORE we
// return from llvm_start_multithreaded().
sys::MemoryFence();
return true;
#else
return false;
#endif
}
void llvm::llvm_stop_multithreaded() {
#ifdef LLVM_MULTITHREADED
assert(multithreaded_mode && "Not currently multithreaded!");
// We fence here to insure that all threaded operations are complete BEFORE we
// return from llvm_stop_multithreaded().
sys::MemoryFence();
multithreaded_mode = false;
delete global_lock;
#endif
}
bool llvm::llvm_is_multithreaded() {
return multithreaded_mode;
}
void llvm::llvm_acquire_global_lock() {
if (multithreaded_mode) global_lock->acquire();
}
void llvm::llvm_release_global_lock() {
if (multithreaded_mode) global_lock->release();
}