From 1fc08f5e9ef733ef1ce6f363fecedc2260e78974 Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Sat, 14 Apr 2012 13:54:10 +0000
Subject: Vendor import of llvm trunk r154661:
 http://llvm.org/svn/llvm-project/llvm/trunk@r154661

---
 lib/Support/ManagedStatic.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'lib/Support/ManagedStatic.cpp')

diff --git a/lib/Support/ManagedStatic.cpp b/lib/Support/ManagedStatic.cpp
index c767c15..098cccb 100644
--- a/lib/Support/ManagedStatic.cpp
+++ b/lib/Support/ManagedStatic.cpp
@@ -27,8 +27,15 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(),
     if (Ptr == 0) {
       void* tmp = Creator ? Creator() : 0;
 
+      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.
@@ -72,4 +79,3 @@ void llvm::llvm_shutdown() {
 
   if (llvm_is_multithreaded()) llvm_stop_multithreaded();
 }
-
-- 
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