Re-apply r211287: Remove support for LLVM runtime multi-threading.

I'll fix the problems in libclang and other projects in ways that don't
require <mutex> until we sort out the cygwin situation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211900 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 9 insertions, 28 deletions

diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
index 0e78ed71fa..8693a3020a 100644
--- a/include/llvm-c/Core.h
+++ b/include/llvm-c/Core.h
@@ -2848,16 +2848,13 @@ void LLVMDisposePassManager(LLVMPassManagerRef PM);
  * @{
  */
 
-/** Allocate and initialize structures needed to make LLVM safe for
-    multithreading. The return value indicates whether multithreaded
-    initialization succeeded. Must be executed in isolation from all
-    other LLVM api calls.
-    @see llvm::llvm_start_multithreaded */
+/** Deprecated: Multi-threading can only be enabled/disabled with the compile
+    time define LLVM_ENABLE_THREADS.  This function always returns
+    LLVMIsMultithreaded(). */
 LLVMBool LLVMStartMultithreaded(void);
 
-/** Deallocate structures necessary to make LLVM safe for multithreading.
-    Must be executed in isolation from all other LLVM api calls.
-    @see llvm::llvm_stop_multithreaded */
+/** Deprecated: Multi-threading can only be enabled/disabled with the compile
+    time define LLVM_ENABLE_THREADS. */
 void LLVMStopMultithreaded(void);
 
 /** Check whether LLVM is executing in thread-safe mode or not.
diff --git a/include/llvm/Support/ManagedStatic.h b/include/llvm/Support/ManagedStatic.h
index 1bb8cea092..d8fbfeb8e2 100644
--- a/include/llvm/Support/ManagedStatic.h
+++ b/include/llvm/Support/ManagedStatic.h
@@ -103,9 +103,6 @@ void llvm_shutdown();
 /// llvm_shutdown() when it is destroyed.
 struct llvm_shutdown_obj {
   llvm_shutdown_obj() { }
-  explicit llvm_shutdown_obj(bool multithreaded) {
-    if (multithreaded) llvm_start_multithreaded();
-  }
   ~llvm_shutdown_obj() { llvm_shutdown(); }
 };
 
diff --git a/include/llvm/Support/Threading.h b/include/llvm/Support/Threading.h
index d84d118679..7e8758407c 100644
--- a/include/llvm/Support/Threading.h
+++ b/include/llvm/Support/Threading.h
@@ -7,7 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// TThis file defines llvm_start_multithreaded() and friends.
+// This file declares helper functions for running LLVM in a multi-threaded
+// environment.
 //
 //===----------------------------------------------------------------------===//
 
@@ -15,22 +16,8 @@
 #define LLVM_SUPPORT_THREADING_H
 
 namespace llvm {
-  /// 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.
+  /// Returns true if LLVM is compiled with support for multi-threading, and
+  /// false otherwise.
   bool llvm_is_multithreaded();
 
   /// llvm_execute_on_thread - Execute the given \p UserFn on a separate