1 //===-- llvm/Support/Threading.h - Control multithreading mode --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares helper functions for running LLVM in a multi-threaded
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_THREADING_H
16 #define LLVM_SUPPORT_THREADING_H
18 #include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
20 #if defined(LLVM_ON_UNIX)
23 #include "llvm/Support/Atomic.h"
27 /// Returns true if LLVM is compiled with support for multi-threading, and
29 bool llvm_is_multithreaded();
31 /// llvm_execute_on_thread - Execute the given \p UserFn on a separate
32 /// thread, passing it the provided \p UserData.
34 /// This function does not guarantee that the code will actually be executed
35 /// on a separate thread or honoring the requested stack size, but tries to do
36 /// so where system support is available.
38 /// \param UserFn - The callback to execute.
39 /// \param UserData - An argument to pass to the callback function.
40 /// \param RequestedStackSize - If non-zero, a requested size (in bytes) for
42 void llvm_execute_on_thread(void (*UserFn)(void*), void *UserData,
43 unsigned RequestedStackSize = 0);
45 #if defined(LLVM_ON_UNIX)
46 typedef std::once_flag once_flag;
47 #define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag
54 typedef volatile sys::cas_flag once_flag;
56 #define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag = Uninitialized
59 /// \brief Execute the function specified as a parameter once.
65 /// LLVM_DEFINE_ONCE_FLAG(flag);
66 /// call_once(flag, foo);
69 /// \param flag Flag used for tracking whether or not this has run.
70 /// \param UserFn Function to call once.
71 void call_once(once_flag &flag, void (*UserFn)(void));