Revert "Revert "Revert 220932.": "Removing the static initializer in ManagedStatic.cpp by using llvm_call_once to initialize the ManagedStatic mutex""

This reverts commit r269577.
Broke NetBSD, waiting for Kamil to investigate

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 269584

1 files changed, 4 insertions, 11 deletions

diff --git a/llvm/lib/Support/ManagedStatic.cpp b/llvm/lib/Support/ManagedStatic.cpp
index b1feddc09ec..b8fb2841e52 100644
--- a/llvm/lib/Support/ManagedStatic.cpp
+++ b/llvm/lib/Support/ManagedStatic.cpp
@@ -16,23 +16,16 @@
 #include "llvm/Support/Atomic.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/MutexGuard.h"
-#include "llvm/Support/Threading.h"
 #include <cassert>
 using namespace llvm;
 
 static const ManagedStaticBase *StaticList = nullptr;
-static sys::Mutex *ManagedStaticMutex = nullptr;
-LLVM_DEFINE_ONCE_FLAG(mutex_init_flag);
 
-static void initializeMutex() {
-  ManagedStaticMutex = new sys::Mutex();
-}
-
-static sys::Mutex* getManagedStaticMutex() {
+static sys::Mutex& getManagedStaticMutex() {
   // We need to use a function local static here, since this can get called
   // during a static constructor and we need to guarantee that it's initialized
   // correctly.
-  call_once(mutex_init_flag, initializeMutex);
+  static sys::Mutex ManagedStaticMutex;
   return ManagedStaticMutex;
 }
 
@@ -40,7 +33,7 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
                                               void (*Deleter)(void*)) const {
   assert(Creator);
   if (llvm_is_multithreaded()) {
-    MutexGuard Lock(*getManagedStaticMutex());
+    MutexGuard Lock(getManagedStaticMutex());
 
     if (!Ptr) {
       void* tmp = Creator();
@@ -90,7 +83,7 @@ void ManagedStaticBase::destroy() const {
 
 /// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
 void llvm::llvm_shutdown() {
-  MutexGuard Lock(*getManagedStaticMutex());
+  MutexGuard Lock(getManagedStaticMutex());
 
   while (StaticList)
     StaticList->destroy();