[C++11] Replace LLVM atomics with std::atomic.

With C++11 we finally have a standardized way to specify atomic operations. Use
them to replace the existing custom implemention. Sadly the translation is not
entirely trivial as std::atomic allows more fine-grained control over the
atomicity. I tried to preserve the old semantics as well as possible.

Differential Revision: http://llvm-reviews.chandlerc.com/D2915

llvm-svn: 202730

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Support/Statistic.cpp b/llvm/lib/Support/Statistic.cpp
index 56c3b0f5659..9d075736b30 100644
--- a/llvm/lib/Support/Statistic.cpp
+++ b/llvm/lib/Support/Statistic.cpp
@@ -76,7 +76,7 @@ void Statistic::RegisterStatistic() {
       StatInfo->addStatistic(this);
 
     TsanHappensBefore(this);
-    sys::MemoryFence();
+    std::atomic_thread_fence(std::memory_order_seq_cst);
     // Remember we have been registered.
     TsanIgnoreWritesBegin();
     Initialized = true;