SelectionDAG: skip barriers for unordered atomic operations

Unordered is strictly weaker than monotonic, so if the latter doesn't have any
barriers then the former certainly shouldn't.

rdar://problem/16548260

llvm-svn: 209901

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 070e929fce7..8d10a80b4d2 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3570,12 +3570,12 @@ static SDValue InsertFenceForAtomic(SDValue Chain, AtomicOrdering Order,
   if (Before) {
     if (Order == AcquireRelease || Order == SequentiallyConsistent)
       Order = Release;
-    else if (Order == Acquire || Order == Monotonic)
+    else if (Order == Acquire || Order == Monotonic || Order == Unordered)
       return Chain;
   } else {
     if (Order == AcquireRelease)
       Order = Acquire;
-    else if (Order == Release || Order == Monotonic)
+    else if (Order == Release || Order == Monotonic || Order == Unordered)
       return Chain;
   }
   SDValue Ops[3];