Removing the static destructor from ManagedStatic.cpp by controlling the allocation and de-allocation of the mutex.

This patch adds a new llvm_call_once function which is used by the ManagedStatic implementation to safely initialize a global to avoid static construction and destruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219638 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/ManagedStatic.cpp

@@ -16,16 +16,22 @@
 #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;
 
-static sys::Mutex& getManagedStaticMutex() {
+static void initializeMutex() {
+  ManagedStaticMutex = new sys::Mutex();
+}
+
+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.
-  static sys::Mutex ManagedStaticMutex;
+  llvm_call_once<initializeMutex>();
   return ManagedStaticMutex;
 }
 
@@ -33,7 +39,7 @@ 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();
@@ -83,8 +89,13 @@ 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();
+    while (StaticList)
+      StaticList->destroy();
+  }
+
+  delete ManagedStaticMutex;
+  ManagedStaticMutex = nullptr;
 }