From 1c0f6ed45a3e4040c827ce0b49aa4c6c90ad5e25 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Thu, 13 Jul 2017 16:56:24 +0000
Subject: [PATCH] Put std::mutex usage behind #ifdefs to pacify the sanitizer
 buildbot

llvm-svn: 307925
---
 llvm/lib/Support/ErrorHandling.cpp | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/llvm/lib/Support/ErrorHandling.cpp b/llvm/lib/Support/ErrorHandling.cpp
index fe69151665c6..2fd4f3ea0d45 100644
--- a/llvm/lib/Support/ErrorHandling.cpp
+++ b/llvm/lib/Support/ErrorHandling.cpp
@@ -45,22 +45,36 @@ static void *ErrorHandlerUserData = nullptr;
 static fatal_error_handler_t BadAllocErrorHandler = nullptr;
 static void *BadAllocErrorHandlerUserData = nullptr;
 
+#if LLVM_ENABLE_THREADS == 1
 // Mutexes to synchronize installing error handlers and calling error handlers.
 // Do not use ManagedStatic, or that may allocate memory while attempting to
 // report an OOM.
+//
+// This usage of std::mutex has to be conditionalized behind ifdefs because
+// of this script:
+//   compiler-rt/lib/sanitizer_common/symbolizer/scripts/build_symbolizer.sh
+// That script attempts to statically link the LLVM symbolizer library with the
+// STL and hide all of its symbols with 'opt -internalize'. To reduce size, it
+// cuts out the threading portions of the hermetic copy of libc++ that it
+// builds. We can remove these ifdefs if that script goes away.
 static std::mutex ErrorHandlerMutex;
 static std::mutex BadAllocErrorHandlerMutex;
+#endif
 
 void llvm::install_fatal_error_handler(fatal_error_handler_t handler,
                                        void *user_data) {
+#if LLVM_ENABLE_THREADS == 1
   std::lock_guard<std::mutex> Lock(ErrorHandlerMutex);
+#endif
   assert(!ErrorHandler && "Error handler already registered!\n");
   ErrorHandler = handler;
   ErrorHandlerUserData = user_data;
 }
 
 void llvm::remove_fatal_error_handler() {
+#if LLVM_ENABLE_THREADS == 1
   std::lock_guard<std::mutex> Lock(ErrorHandlerMutex);
+#endif
   ErrorHandler = nullptr;
   ErrorHandlerUserData = nullptr;
 }
@@ -83,7 +97,9 @@ void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
   {
     // Only acquire the mutex while reading the handler, so as not to invoke a
     // user-supplied callback under a lock.
+#if LLVM_ENABLE_THREADS == 1
     std::lock_guard<std::mutex> Lock(ErrorHandlerMutex);
+#endif
     handler = ErrorHandler;
     handlerData = ErrorHandlerUserData;
   }
@@ -112,14 +128,18 @@ void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
 
 void llvm::install_bad_alloc_error_handler(fatal_error_handler_t handler,
                                            void *user_data) {
+#if LLVM_ENABLE_THREADS == 1
   std::lock_guard<std::mutex> Lock(BadAllocErrorHandlerMutex);
+#endif
   assert(!ErrorHandler && "Bad alloc error handler already registered!\n");
   BadAllocErrorHandler = handler;
   BadAllocErrorHandlerUserData = user_data;
 }
 
 void llvm::remove_bad_alloc_error_handler() {
+#if LLVM_ENABLE_THREADS == 1
   std::lock_guard<std::mutex> Lock(BadAllocErrorHandlerMutex);
+#endif
   BadAllocErrorHandler = nullptr;
   BadAllocErrorHandlerUserData = nullptr;
 }
@@ -130,7 +150,9 @@ void llvm::report_bad_alloc_error(const char *Reason, bool GenCrashDiag) {
   {
     // Only acquire the mutex while reading the handler, so as not to invoke a
     // user-supplied callback under a lock.
+#if LLVM_ENABLE_THREADS == 1
     std::lock_guard<std::mutex> Lock(BadAllocErrorHandlerMutex);
+#endif
     Handler = BadAllocErrorHandler;
     HandlerData = BadAllocErrorHandlerUserData;
   }