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c6ece6bf3b
libstdc++ (or in compilers, or somewhere, I can't track it down) that causes unittests that use INITIALIZE_PASS to crash. The analysis I've been able to do is that inside libstdc++'s implementation of std::call_once, it uses pthread_once, and when that returns an error code it throws std::system_error which then eventually calls std::terminate. Hopefully some of the folks who work on PPC can try to sort out what's going on here. Until then, they'll have to use the fallback implementation. llvm-svn: 271821
121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
//===-- llvm/Support/Threading.h - Control multithreading mode --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares helper functions for running LLVM in a multi-threaded
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// environment.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_THREADING_H
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#define LLVM_SUPPORT_THREADING_H
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#include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
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#include "llvm/Support/Compiler.h"
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#include <ciso646> // So we can check the C++ standard lib macros.
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#include <functional>
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// We use std::call_once on all Unix platforms except for NetBSD with
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// libstdc++. That platform has a bug they are working to fix, and they'll
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// remove the NetBSD checks once fixed.
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#if defined(LLVM_ON_UNIX) && \
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!(defined(__NetBSD__) && !defined(_LIBCPP_VERSION)) && !defined(__ppc__)
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#define LLVM_THREADING_USE_STD_CALL_ONCE 1
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#else
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#define LLVM_THREADING_USE_STD_CALL_ONCE 0
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#endif
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#if LLVM_THREADING_USE_STD_CALL_ONCE
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#include <mutex>
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#else
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#include "llvm/Support/Atomic.h"
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#endif
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namespace llvm {
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/// Returns true if LLVM is compiled with support for multi-threading, and
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/// false otherwise.
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bool llvm_is_multithreaded();
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/// llvm_execute_on_thread - Execute the given \p UserFn on a separate
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/// thread, passing it the provided \p UserData and waits for thread
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/// completion.
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///
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/// This function does not guarantee that the code will actually be executed
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/// on a separate thread or honoring the requested stack size, but tries to do
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/// so where system support is available.
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///
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/// \param UserFn - The callback to execute.
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/// \param UserData - An argument to pass to the callback function.
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/// \param RequestedStackSize - If non-zero, a requested size (in bytes) for
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/// the thread stack.
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void llvm_execute_on_thread(void (*UserFn)(void*), void *UserData,
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unsigned RequestedStackSize = 0);
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#if LLVM_THREADING_USE_STD_CALL_ONCE
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typedef std::once_flag once_flag;
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/// This macro is the only way you should define your once flag for LLVM's
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/// call_once.
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#define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag
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#else
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enum InitStatus { Uninitialized = 0, Wait = 1, Done = 2 };
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typedef volatile sys::cas_flag once_flag;
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/// This macro is the only way you should define your once flag for LLVM's
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/// call_once.
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#define LLVM_DEFINE_ONCE_FLAG(flag) static once_flag flag = Uninitialized
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#endif
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/// \brief Execute the function specified as a parameter once.
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///
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/// Typical usage:
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/// \code
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/// void foo() {...};
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/// ...
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/// LLVM_DEFINE_ONCE_FLAG(flag);
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/// call_once(flag, foo);
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/// \endcode
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///
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/// \param flag Flag used for tracking whether or not this has run.
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/// \param F Function to call once.
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template <typename Function, typename... Args>
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void call_once(once_flag &flag, Function &&F, Args &&... ArgList) {
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#if LLVM_THREADING_USE_STD_CALL_ONCE
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std::call_once(flag, std::forward<Function>(F),
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std::forward<Args>(ArgList)...);
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#else
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// For other platforms we use a generic (if brittle) version based on our
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// atomics.
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sys::cas_flag old_val = sys::CompareAndSwap(&flag, Wait, Uninitialized);
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if (old_val == Uninitialized) {
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std::forward<Function>(F)(std::forward<Args>(ArgList)...);
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sys::MemoryFence();
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TsanIgnoreWritesBegin();
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TsanHappensBefore(&flag);
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flag = Done;
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TsanIgnoreWritesEnd();
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} else {
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// Wait until any thread doing the call has finished.
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sys::cas_flag tmp = flag;
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sys::MemoryFence();
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while (tmp != Done) {
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tmp = flag;
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sys::MemoryFence();
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}
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}
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TsanHappensAfter(&flag);
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#endif
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}
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}
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#endif
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