Revert r254592 (virtual dtor in SCEVPredicate).

[oota-llvm.git] / lib / Support / ManagedStatic.cpp

diff --git a/lib/Support/ManagedStatic.cpp b/lib/Support/ManagedStatic.cpp
index ced2b13b3a14ed14f65e9c7fa897a2e787665d82..9868207b14ff2733ba7c8ea75b81ec6a98b7abe4 100644 (file)
--- a/lib/Support/ManagedStatic.cpp
+++ b/lib/Support/ManagedStatic.cpp
@@ -14,36 +14,28 @@
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Atomic.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Mutex.h"
 #include "llvm/Support/MutexGuard.h"
 #include <cassert>
-#include <mutex>
 using namespace llvm;
 
 static const ManagedStaticBase *StaticList = nullptr;
 
-// ManagedStatics can get created during execution of static constructors.  As a
-// result, we cannot use a global static std::mutex object for the lock since it
-// may not have been constructed.  Instead, we do a call-once initialization of
-// a pointer to a mutex.  This also means that we must not "initialize" the
-// mutex with nullptr, otherwise it might get reset to nullptr after being
-// initialized by std::call_once.
-static std::once_flag MutexInitializationFlag;
-static std::recursive_mutex *ManagedStaticMutex;
-
-namespace {
-  void InitializeManagedStaticMutex() {
-    std::call_once(MutexInitializationFlag,
-        []() { ManagedStaticMutex = new std::recursive_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;
+  return ManagedStaticMutex;
 }
 
 void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
                                               void (*Deleter)(void*)) const {
   assert(Creator);
   if (llvm_is_multithreaded()) {
-    InitializeManagedStaticMutex();
+    MutexGuard Lock(getManagedStaticMutex());
 
-    std::lock_guard<std::recursive_mutex> Lock(*ManagedStaticMutex);
     if (!Ptr) {
       void* tmp = Creator();
 
@@ -92,8 +84,7 @@ void ManagedStaticBase::destroy() const {
 
 /// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
 void llvm::llvm_shutdown() {
-  InitializeManagedStaticMutex();
-  std::lock_guard<std::recursive_mutex> Lock(*ManagedStaticMutex);
+  MutexGuard Lock(getManagedStaticMutex());
 
   while (StaticList)
     StaticList->destroy();