Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/lib/Support/RWMutex.cpp

@@ -0,0 +1,124 @@
+//===- RWMutex.cpp - Reader/Writer Mutual Exclusion Lock --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the llvm::sys::RWMutex class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/RWMutex.h"
+#include "llvm/Config/config.h"
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
+#if !defined(LLVM_ENABLE_THREADS) || LLVM_ENABLE_THREADS == 0
+// Define all methods as no-ops if threading is explicitly disabled
+
+using namespace llvm;
+using namespace sys;
+
+RWMutexImpl::RWMutexImpl() = default;
+RWMutexImpl::~RWMutexImpl() = default;
+
+bool RWMutexImpl::reader_acquire() { return true; }
+bool RWMutexImpl::reader_release() { return true; }
+bool RWMutexImpl::writer_acquire() { return true; }
+bool RWMutexImpl::writer_release() { return true; }
+
+#else
+
+#if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_RWLOCK_INIT)
+
+#include <cassert>
+#include <cstdlib>
+#include <pthread.h>
+
+using namespace llvm;
+using namespace sys;
+
+// Construct a RWMutex using pthread calls
+RWMutexImpl::RWMutexImpl()
+{
+  // Declare the pthread_rwlock data structures
+  pthread_rwlock_t* rwlock =
+    static_cast<pthread_rwlock_t*>(malloc(sizeof(pthread_rwlock_t)));
+
+#ifdef __APPLE__
+  // Workaround a bug/mis-feature in Darwin's pthread_rwlock_init.
+  bzero(rwlock, sizeof(pthread_rwlock_t));
+#endif
+
+  // Initialize the rwlock
+  int errorcode = pthread_rwlock_init(rwlock, nullptr);
+  (void)errorcode;
+  assert(errorcode == 0);
+
+  // Assign the data member
+  data_ = rwlock;
+}
+
+// Destruct a RWMutex
+RWMutexImpl::~RWMutexImpl()
+{
+  pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+  assert(rwlock != nullptr);
+  pthread_rwlock_destroy(rwlock);
+  free(rwlock);
+}
+
+bool
+RWMutexImpl::reader_acquire()
+{
+  pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+  assert(rwlock != nullptr);
+
+  int errorcode = pthread_rwlock_rdlock(rwlock);
+  return errorcode == 0;
+}
+
+bool
+RWMutexImpl::reader_release()
+{
+  pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+  assert(rwlock != nullptr);
+
+  int errorcode = pthread_rwlock_unlock(rwlock);
+  return errorcode == 0;
+}
+
+bool
+RWMutexImpl::writer_acquire()
+{
+  pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+  assert(rwlock != nullptr);
+
+  int errorcode = pthread_rwlock_wrlock(rwlock);
+  return errorcode == 0;
+}
+
+bool
+RWMutexImpl::writer_release()
+{
+  pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+  assert(rwlock != nullptr);
+
+  int errorcode = pthread_rwlock_unlock(rwlock);
+  return errorcode == 0;
+}
+
+#elif defined(LLVM_ON_UNIX)
+#include "Unix/RWMutex.inc"
+#elif defined( LLVM_ON_WIN32)
+#include "Windows/RWMutex.inc"
+#else
+#warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in Support/Mutex.cpp
+#endif
+#endif