X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FSupport%2FManagedStatic.cpp;h=b1feddc09ec63ea611b78aa690831f7b03bb83e2;hb=153cd65fd46ffdcd416b64f7ec51dff808fc453f;hp=8de8ecd69f14dcbea4829eb9987ac790320241b5;hpb=d283566319a5bec8bfa2223580d92c86e01af13b;p=oota-llvm.git

diff --git a/lib/Support/ManagedStatic.cpp b/lib/Support/ManagedStatic.cpp
index 8de8ecd69f1..b1feddc09ec 100644
--- a/lib/Support/ManagedStatic.cpp
+++ b/lib/Support/ManagedStatic.cpp
@@ -2,8 +2,8 @@
 //
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by Chris Lattner and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
@@ -12,21 +12,64 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/ManagedStatic.h"
+#include "llvm/Config/config.h"
+#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 = 0;
+static const ManagedStaticBase *StaticList = nullptr;
+static sys::Mutex *ManagedStaticMutex = nullptr;
+LLVM_DEFINE_ONCE_FLAG(mutex_init_flag);
 
-void ManagedStaticBase::RegisterManagedStatic(void *ObjPtr,
+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.
+  call_once(mutex_init_flag, initializeMutex);
+  return ManagedStaticMutex;
+}
+
+void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
                                               void (*Deleter)(void*)) const {
-  assert(Ptr == 0 && DeleterFn == 0 && Next == 0 &&
-         "Partially init static?");
-  Ptr = ObjPtr;
-  DeleterFn = Deleter;
+  assert(Creator);
+  if (llvm_is_multithreaded()) {
+    MutexGuard Lock(*getManagedStaticMutex());
+
+    if (!Ptr) {
+      void* tmp = Creator();
+
+      TsanHappensBefore(this);
+      sys::MemoryFence();
+
+      // This write is racy against the first read in the ManagedStatic
+      // accessors. The race is benign because it does a second read after a
+      // memory fence, at which point it isn't possible to get a partial value.
+      TsanIgnoreWritesBegin();
+      Ptr = tmp;
+      TsanIgnoreWritesEnd();
+      DeleterFn = Deleter;
+      
+      // Add to list of managed statics.
+      Next = StaticList;
+      StaticList = this;
+    }
+  } else {
+    assert(!Ptr && !DeleterFn && !Next &&
+           "Partially initialized ManagedStatic!?");
+    Ptr = Creator();
+    DeleterFn = Deleter;
   
-  // Add to list of managed statics.
-  Next = StaticList;
-  StaticList = this;
+    // Add to list of managed statics.
+    Next = StaticList;
+    StaticList = this;
+  }
 }
 
 void ManagedStaticBase::destroy() const {
@@ -35,19 +78,20 @@ void ManagedStaticBase::destroy() const {
          "Not destroyed in reverse order of construction?");
   // Unlink from list.
   StaticList = Next;
-  Next = 0;
+  Next = nullptr;
 
   // Destroy memory.
   DeleterFn(Ptr);
   
   // Cleanup.
-  Ptr = 0;
-  DeleterFn = 0;
+  Ptr = nullptr;
+  DeleterFn = nullptr;
 }
 
 /// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
 void llvm::llvm_shutdown() {
+  MutexGuard Lock(*getManagedStaticMutex());
+
   while (StaticList)
     StaticList->destroy();
 }
-