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0a262ba7c3
These patches make threading optional in LLVM. The configuration scripts are now modified to accept a --disable-threads switch. If this is used, the Mutex class will be implemented with all functions as no-op. Furthermore, linking against libpthread will not be done. Finally, the ParallelJIT example needs libpthread so its makefile was changed to always add -lpthread to the link line. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23003 91177308-0d34-0410-b5e6-96231b3b80d8
160 lines
4.4 KiB
C++
160 lines
4.4 KiB
C++
//===- Mutex.cpp - Mutual Exclusion Lock ------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Reid Spencer and is distributed under the
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// University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the llvm::sys::Mutex class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Config/config.h"
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#include "llvm/System/Mutex.h"
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//===----------------------------------------------------------------------===//
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//=== WARNING: Implementation here must contain only TRULY operating system
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//=== independent code.
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//===----------------------------------------------------------------------===//
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#if !defined(ENABLE_THREADS) || ENABLE_THREADS == 0
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// Define all methods as no-ops if threading is explicitly disabled
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namespace llvm {
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using namespace sys;
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Mutex::Mutex( bool recursive) { }
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Mutex::~Mutex() { }
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bool Mutex::acquire() { return true; }
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bool Mutex::release() { return true; }
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bool Mutex::tryacquire() { return true; }
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}
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#else
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#if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_MUTEX_LOCK)
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#include <cassert>
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#include <pthread.h>
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#include <stdlib.h>
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namespace llvm {
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using namespace sys;
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// This variable is useful for situations where the pthread library has been
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// compiled with weak linkage for its interface symbols. This allows the
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// threading support to be turned off by simply not linking against -lpthread.
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// In that situation, the value of pthread_mutex_init will be 0 and
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// consequently pthread_enabled will be false. In such situations, all the
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// pthread operations become no-ops and the functions all return false. If
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// pthread_mutex_init does have an address, then mutex support is enabled.
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// Note: all LLVM tools will link against -lpthread if its available since it
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// is configured into the LIBS variable.
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// Note: this line of code generates a warning if pthread_mutex_init is not
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// declared with weak linkage. It's safe to ignore the warning.
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static const bool pthread_enabled = static_cast<bool>(pthread_mutex_init);
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// Construct a Mutex using pthread calls
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Mutex::Mutex( bool recursive)
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: data_(0)
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{
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if (pthread_enabled)
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{
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// Declare the pthread_mutex data structures
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pthread_mutex_t* mutex =
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static_cast<pthread_mutex_t*>(malloc(sizeof(pthread_mutex_t)));
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pthread_mutexattr_t attr;
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// Initialize the mutex attributes
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int errorcode = pthread_mutexattr_init(&attr);
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assert(errorcode == 0);
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// Initialize the mutex as a recursive mutex, if requested, or normal
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// otherwise.
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int kind = ( recursive ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL );
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errorcode = pthread_mutexattr_settype(&attr, kind);
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assert(errorcode == 0);
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#ifndef __FreeBSD__
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// Make it a process local mutex
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errorcode = pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_PRIVATE);
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#endif
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// Initialize the mutex
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errorcode = pthread_mutex_init(mutex, &attr);
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assert(errorcode == 0);
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// Destroy the attributes
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errorcode = pthread_mutexattr_destroy(&attr);
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assert(errorcode == 0);
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// Assign the data member
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data_ = mutex;
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}
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}
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// Destruct a Mutex
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Mutex::~Mutex()
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{
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if (pthread_enabled)
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{
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pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
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assert(mutex != 0);
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int errorcode = pthread_mutex_destroy(mutex);
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assert(mutex != 0);
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}
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}
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bool
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Mutex::acquire()
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{
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if (pthread_enabled)
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{
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pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
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assert(mutex != 0);
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int errorcode = pthread_mutex_lock(mutex);
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return errorcode == 0;
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}
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return false;
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}
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bool
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Mutex::release()
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{
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if (pthread_enabled)
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{
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pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
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assert(mutex != 0);
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int errorcode = pthread_mutex_unlock(mutex);
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return errorcode == 0;
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}
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return false;
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}
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bool
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Mutex::tryacquire()
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{
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if (pthread_enabled)
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{
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pthread_mutex_t* mutex = reinterpret_cast<pthread_mutex_t*>(data_);
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assert(mutex != 0);
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int errorcode = pthread_mutex_trylock(mutex);
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return errorcode == 0;
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}
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return false;
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}
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}
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#elif defined(LLVM_ON_UNIX)
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#include "Unix/Mutex.inc"
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#elif defined( LLVM_ON_WIN32)
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#include "Win32/Mutex.inc"
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#else
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#warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in System/Mutex.cpp
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#endif
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#endif
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