Revert r211066, 211067, 211068, 211069, 211070.

These were committed accidentally from the wrong branch before having
a review sign-off.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211072 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Threading.h

@@ -7,21 +7,40 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines helper functions for running LLVM in a multi-threaded
-// environment.
+// TThis file defines llvm_start_multithreaded() and friends.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_SUPPORT_THREADING_H
 #define LLVM_SUPPORT_THREADING_H
 
-#include "llvm/Support/Mutex.h"
-
 namespace llvm {
-  /// llvm_is_multithreaded - returns true if LLVM is compiled with support
-  /// for multiple threads, and false otherwise.
+  /// llvm_start_multithreaded - Allocate and initialize structures needed to
+  /// make LLVM safe for multithreading.  The return value indicates whether
+  /// multithreaded initialization succeeded.  LLVM will still be operational
+  /// on "failed" return, and will still be safe for hosting threading
+  /// applications in the JIT, but will not be safe for concurrent calls to the
+  /// LLVM APIs.
+  /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
+  bool llvm_start_multithreaded();
+
+  /// llvm_stop_multithreaded - Deallocate structures necessary to make LLVM
+  /// safe for multithreading.
+  /// THIS MUST EXECUTE IN ISOLATION FROM ALL OTHER LLVM API CALLS.
+  void llvm_stop_multithreaded();
+
+  /// llvm_is_multithreaded - Check whether LLVM is executing in thread-safe
+  /// mode or not.
   bool llvm_is_multithreaded();
 
+  /// acquire_global_lock - Acquire the global lock.  This is a no-op if called
+  /// before llvm_start_multithreaded().
+  void llvm_acquire_global_lock();
+
+  /// release_global_lock - Release the global lock.  This is a no-op if called
+  /// before llvm_start_multithreaded().
+  void llvm_release_global_lock();
+
   /// llvm_execute_on_thread - Execute the given \p UserFn on a separate
   /// thread, passing it the provided \p UserData.
   ///