1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Transforms/IPO/ArgumentPromotion.cpp b/lib/Transforms/IPO/ArgumentPromotion.cpp
index b25cbcad3b9d0..76c4a8fbc16e9 100644
--- a/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -847,10 +847,20 @@ promoteArguments(Function *F, function_ref<AAResults &(Function &F)> AARGetter,
     if (CS.getInstruction() == nullptr || !CS.isCallee(&U))
       return nullptr;
 
+    // Can't change signature of musttail callee
+    if (CS.isMustTailCall())
+      return nullptr;
+
     if (CS.getInstruction()->getParent()->getParent() == F)
       isSelfRecursive = true;
   }
 
+  // Can't change signature of musttail caller
+  // FIXME: Support promoting whole chain of musttail functions
+  for (BasicBlock &BB : *F)
+    if (BB.getTerminatingMustTailCall())
+      return nullptr;
+
   const DataLayout &DL = F->getParent()->getDataLayout();
 
   AAResults &AAR = AARGetter(*F);