Revert r211121 (and r211285), "Change libclang initialization to use std::call_once...

It broke mingw builder and cygwin-clang stage2, possibly lack of tls in <mutex>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211593 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 45e578609599ac6df7d98f62b9dce580887e0c06..787c28b21e25b240b050e4909c47e0a4d4ceb998 100644 (file)
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -51,7 +51,6 @@
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
-#include <mutex>
 
 #ifdef __APPLE__
 #include <pthread.h>
@@ -2573,8 +2572,8 @@ buildPieces(unsigned NameFlags, bool IsMemberRefExpr,
 // Misc. API hooks.
 //===----------------------------------------------------------------------===//               
 
-static llvm::sys::Mutex LoggingMutex;
-static std::once_flag LibclangGlobalInitFlag;
+static llvm::sys::Mutex EnableMultithreadingMutex;
+static bool EnabledMultithreading;
 
 static void fatal_error_handler(void *user_data, const std::string& reason,
                                 bool gen_crash_diag) {
@@ -2584,10 +2583,6 @@ static void fatal_error_handler(void *user_data, const std::string& reason,
   ::abort();
 }
 
-static void initializeLibClang() {
-  llvm::install_fatal_error_handler(fatal_error_handler, nullptr);
-}
-
 extern "C" {
 CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
                           int displayDiagnostics) {
@@ -2596,7 +2591,15 @@ CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
   if (!getenv("LIBCLANG_DISABLE_CRASH_RECOVERY"))
     llvm::CrashRecoveryContext::Enable();
 
-  std::call_once(LibclangGlobalInitFlag, initializeLibClang);
+  // Enable support for multithreading in LLVM.
+  {
+    llvm::sys::ScopedLock L(EnableMultithreadingMutex);
+    if (!EnabledMultithreading) {
+      llvm::install_fatal_error_handler(fatal_error_handler, nullptr);
+      llvm::llvm_start_multithreaded();
+      EnabledMultithreading = true;
+    }
+  }
 
   CIndexer *CIdxr = new CIndexer();
   if (excludeDeclarationsFromPCH)
@@ -6974,7 +6977,7 @@ Logger &cxindex::Logger::operator<<(const llvm::format_object_base &Fmt) {
 cxindex::Logger::~Logger() {
   LogOS.flush();
 
-  llvm::sys::ScopedLock L(LoggingMutex);
+  llvm::sys::ScopedLock L(EnableMultithreadingMutex);
 
   static llvm::TimeRecord sBeginTR = llvm::TimeRecord::getCurrentTime();