1 files changed, 9 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 9ca646534e2b..996c95bd5f07 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5832,6 +5832,15 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
 
   const Value *SwiftErrorVal = nullptr;
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+
+  // We can't tail call inside a function with a swifterror argument. Lowering
+  // does not support this yet. It would have to move into the swifterror
+  // register before the call.
+  auto *Caller = CS.getInstruction()->getParent()->getParent();
+  if (TLI.supportSwiftError() &&
+      Caller->getAttributes().hasAttrSomewhere(Attribute::SwiftError))
+    isTailCall = false;
+
   for (ImmutableCallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
        i != e; ++i) {
     const Value *V = *i;