1 files changed, 6 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index f21c1bf4e914..ad51bab8f30b 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -515,9 +515,14 @@ void AtomicExpand::expandAtomicStore(StoreInst *SI) {
   // It is the responsibility of the target to only signal expansion via
   // shouldExpandAtomicRMW in cases where this is required and possible.
   IRBuilder<> Builder(SI);
+  AtomicOrdering Ordering = SI->getOrdering();
+  assert(Ordering != AtomicOrdering::NotAtomic);
+  AtomicOrdering RMWOrdering = Ordering == AtomicOrdering::Unordered
+                                   ? AtomicOrdering::Monotonic
+                                   : Ordering;
   AtomicRMWInst *AI = Builder.CreateAtomicRMW(
       AtomicRMWInst::Xchg, SI->getPointerOperand(), SI->getValueOperand(),
-      SI->getAlign(), SI->getOrdering());
+      SI->getAlign(), RMWOrdering);
   SI->eraseFromParent();
 
   // Now we have an appropriate swap instruction, lower it as usual.