Revert "Remove support for runtime multi-threading."

This reverts revision r210600.

llvm-svn: 210603

1 files changed, 2 insertions, 6 deletions

diff --git a/llvm/lib/Support/ErrorHandling.cpp b/llvm/lib/Support/ErrorHandling.cpp
index b9e4eabe926..342c4f05cc9 100644
--- a/llvm/lib/Support/ErrorHandling.cpp
+++ b/llvm/lib/Support/ErrorHandling.cpp
@@ -23,7 +23,6 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstdlib>
-#include <mutex>
 
 #if defined(HAVE_UNISTD_H)
 # include <unistd.h>
@@ -38,18 +37,16 @@ using namespace llvm;
 static fatal_error_handler_t ErrorHandler = nullptr;
 static void *ErrorHandlerUserData = nullptr;
 
-static llvm::recursive_mutex ErrorHandlerMutex;
-
 void llvm::install_fatal_error_handler(fatal_error_handler_t handler,
                                        void *user_data) {
-  std::lock_guard<llvm::recursive_mutex> Lock(ErrorHandlerMutex);
+  assert(!llvm_is_multithreaded() &&
+         "Cannot register error handlers after starting multithreaded mode!\n");
   assert(!ErrorHandler && "Error handler already registered!\n");
   ErrorHandler = handler;
   ErrorHandlerUserData = user_data;
 }
 
 void llvm::remove_fatal_error_handler() {
-  std::lock_guard<llvm::recursive_mutex> Lock(ErrorHandlerMutex);
   ErrorHandler = nullptr;
 }
 
@@ -66,7 +63,6 @@ void llvm::report_fatal_error(StringRef Reason, bool GenCrashDiag) {
 }
 
 void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
-  std::lock_guard<llvm::recursive_mutex> Lock(ErrorHandlerMutex);
   if (ErrorHandler) {
     ErrorHandler(ErrorHandlerUserData, Reason.str(), GenCrashDiag);
   } else {