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5202bf068f
This is the second part of recommit of r325224. The previous part was committed in r325426, which deals with C++ memory allocation. Solution for C memory allocation involved functions `llvm::malloc` and similar. This was a fragile solution because it caused ambiguity errors in some cases. In this commit the new functions have names like `llvm::safe_malloc`. The relevant part of original comment is below, updated for new function names. Analysis of fails in the case of out of memory errors can be tricky on Windows. Such error emerges at the point where memory allocation function fails, but manifests itself when null pointer is used. These two points may be distant from each other. Besides, next runs may not exhibit allocation error. In some cases memory is allocated by a call to some of C allocation functions, malloc, calloc and realloc. They are used for interoperability with C code, when allocated object has variable size and when it is necessary to avoid call of constructors. In many calls the result is not checked for null pointer. To simplify checks, new functions are defined in the namespace 'llvm': `safe_malloc`, `safe_calloc` and `safe_realloc`. They behave as corresponding standard functions but produce fatal error if allocation fails. This change replaces the standard functions like 'malloc' in the cases when the result of the allocation function is not checked for null pointer. Finally, there are plain C code, that uses malloc and similar functions. If the result is not checked, assert statement is added. Differential Revision: https://reviews.llvm.org/D43010 llvm-svn: 325551
126 lines
3.2 KiB
C++
126 lines
3.2 KiB
C++
//===- RWMutex.cpp - Reader/Writer 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 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 implements the llvm::sys::RWMutex class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/RWMutex.h"
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#include "llvm/Config/config.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(LLVM_ENABLE_THREADS) || LLVM_ENABLE_THREADS == 0
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// Define all methods as no-ops if threading is explicitly disabled
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using namespace llvm;
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using namespace sys;
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RWMutexImpl::RWMutexImpl() = default;
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RWMutexImpl::~RWMutexImpl() = default;
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bool RWMutexImpl::reader_acquire() { return true; }
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bool RWMutexImpl::reader_release() { return true; }
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bool RWMutexImpl::writer_acquire() { return true; }
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bool RWMutexImpl::writer_release() { return true; }
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#else
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#if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_RWLOCK_INIT)
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#include <cassert>
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#include <cstdlib>
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#include <pthread.h>
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using namespace llvm;
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using namespace sys;
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// Construct a RWMutex using pthread calls
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RWMutexImpl::RWMutexImpl()
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{
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// Declare the pthread_rwlock data structures
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pthread_rwlock_t* rwlock =
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static_cast<pthread_rwlock_t*>(safe_malloc(sizeof(pthread_rwlock_t)));
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#ifdef __APPLE__
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// Workaround a bug/mis-feature in Darwin's pthread_rwlock_init.
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bzero(rwlock, sizeof(pthread_rwlock_t));
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#endif
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// Initialize the rwlock
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int errorcode = pthread_rwlock_init(rwlock, nullptr);
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(void)errorcode;
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assert(errorcode == 0);
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// Assign the data member
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data_ = rwlock;
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}
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// Destruct a RWMutex
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RWMutexImpl::~RWMutexImpl()
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{
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pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
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assert(rwlock != nullptr);
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pthread_rwlock_destroy(rwlock);
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free(rwlock);
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}
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bool
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RWMutexImpl::reader_acquire()
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{
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pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
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assert(rwlock != nullptr);
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int errorcode = pthread_rwlock_rdlock(rwlock);
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return errorcode == 0;
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}
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bool
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RWMutexImpl::reader_release()
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{
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pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
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assert(rwlock != nullptr);
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int errorcode = pthread_rwlock_unlock(rwlock);
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return errorcode == 0;
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}
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bool
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RWMutexImpl::writer_acquire()
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{
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pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
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assert(rwlock != nullptr);
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int errorcode = pthread_rwlock_wrlock(rwlock);
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return errorcode == 0;
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}
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bool
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RWMutexImpl::writer_release()
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{
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pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
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assert(rwlock != nullptr);
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int errorcode = pthread_rwlock_unlock(rwlock);
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return errorcode == 0;
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}
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#elif defined(LLVM_ON_UNIX)
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#include "Unix/RWMutex.inc"
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#elif defined( LLVM_ON_WIN32)
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#include "Windows/RWMutex.inc"
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#else
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#warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in Support/Mutex.cpp
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#endif
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#endif
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