Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -291,12 +291,13 @@
   int Index = Offset;
   if (const auto *IE = dyn_cast<InsertElementInst>(InsertInst)) {
     if (const auto *CI = dyn_cast<ConstantInt>(IE->getOperand(2))) {
-      auto *VT = cast<FixedVectorType>(IE->getType());
-      if (CI->getValue().uge(VT->getNumElements()))
-        return None;
-      Index *= VT->getNumElements();
-      Index += CI->getZExtValue();
-      return Index;
+      if (const auto *VT = dyn_cast<FixedVectorType>(IE->getType())) {
+        if (CI->getValue().uge(VT->getNumElements()))
+          return None;
+        Index *= VT->getNumElements();
+        Index += CI->getZExtValue();
+        return Index;
+      }
     }
     return None;
   }