lib/Support/Threading.cpp

   1 //===-- llvm/Support/Threading.cpp- Control multithreading mode --*- 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 llvm_start_multithreaded() and friends.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/Threading.h"
  15 #include "llvm/System/Atomic.h"
  16 #include "llvm/System/Mutex.h"
  17 #include <cassert>
  18
  19 using namespace llvm;
  20
  21 static bool multithreaded_mode = false;
  22
  23 static sys::Mutex* global_lock = 0;
  24
  25 bool llvm::llvm_start_multithreaded() {
  26 #ifdef LLVM_MULTITHREADED
  27   assert(!multithreaded_mode && "Already multithreaded!");
  28   multithreaded_mode = true;
  29   global_lock = new sys::Mutex(true);
  30
  31   // We fence here to ensure that all initialization is complete BEFORE we
  32   // return from llvm_start_multithreaded().
  33   sys::MemoryFence();
  34   return true;
  35 #else
  36   return false;
  37 #endif
  38 }
  39
  40 void llvm::llvm_stop_multithreaded() {
  41 #ifdef LLVM_MULTITHREADED
  42   assert(multithreaded_mode && "Not currently multithreaded!");
  43
  44   // We fence here to insure that all threaded operations are complete BEFORE we
  45   // return from llvm_stop_multithreaded().
  46   sys::MemoryFence();
  47
  48   multithreaded_mode = false;
  49   delete global_lock;
  50 #endif
  51 }
  52
  53 bool llvm::llvm_is_multithreaded() {
  54   return multithreaded_mode;
  55 }
  56
  57 void llvm::llvm_acquire_global_lock() {
  58   if (multithreaded_mode) global_lock->acquire();
  59 }
  60
  61 void llvm::llvm_release_global_lock() {
  62   if (multithreaded_mode) global_lock->release();
  63 }