Use atomic operations when accessing statistics, and make the lazy initialization of statistics actually threadsafe.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74005 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/Support/Statistic.cpp b/lib/Support/Statistic.cpp
index 6c652f8d3f..33570b0ee5 100644
--- a/lib/Support/Statistic.cpp
+++ b/lib/Support/Statistic.cpp
@@ -66,10 +66,14 @@ void Statistic::RegisterStatistic() {
   // If stats are enabled, inform StatInfo that this statistic should be
   // printed.
   sys::ScopedLock Writer(&*StatLock);
-  if (Enabled)
-    StatInfo->addStatistic(this);
-  // Remember we have been registered.
-  Initialized = true;
+  if (!Initialized) {
+    if (Enabled)
+      StatInfo->addStatistic(this);
+    
+    sys::MemoryFence();
+    // Remember we have been registered.
+    Initialized = true;
+  }
 }
 
 namespace {