1 files changed, 63 insertions, 0 deletions
diff --git a/lib/Support/Threading.cpp b/lib/Support/Threading.cpp
new file mode 100644
index 0000000000..a5876487e0
--- /dev/null
+++ b/lib/Support/Threading.cpp
@@ -0,0 +1,63 @@
+//===-- llvm/Support/Threading.cpp- Control multithreading mode --*- 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 llvm_start_multithreaded() and friends.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Threading.h"
+#include "llvm/System/Atomic.h"
+#include "llvm/System/Mutex.h"
+#include <cassert>
+
+using namespace llvm;
+
+static bool multithreaded_mode = false;
+
+static sys::Mutex* global_lock = 0;
+
+bool llvm::llvm_start_multithreaded() {
+#ifdef LLVM_MULTITHREADED
+  assert(!multithreaded_mode && "Already multithreaded!");
+  multithreaded_mode = true;
+  global_lock = new sys::Mutex(true);
+  
+  // We fence here to ensure that all initialization is complete BEFORE we
+  // return from llvm_start_multithreaded().
+  sys::MemoryFence();
+  return true;
+#else
+  return false;
+#endif
+}
+
+void llvm::llvm_stop_multithreaded() {
+#ifdef LLVM_MULTITHREADED
+  assert(multithreaded_mode && "Not currently multithreaded!");
+  
+  // We fence here to insure that all threaded operations are complete BEFORE we
+  // return from llvm_stop_multithreaded().
+  sys::MemoryFence();
+  
+  multithreaded_mode = false;
+  delete global_lock;
+#endif
+}
+
+bool llvm::llvm_is_multithreaded() {
+  return multithreaded_mode;
+}
+
+void llvm::llvm_acquire_global_lock() {
+  if (multithreaded_mode) global_lock->acquire();
+}
+
+void llvm::llvm_release_global_lock() {
+  if (multithreaded_mode) global_lock->release();
+}
+\ No newline at end of file