diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3458,7 +3458,6 @@
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   EVT VT = TLI.getValueType(DAG.getDataLayout(), I.getType());
   EVT SrcVT = Src1.getValueType();
-  unsigned SrcNumElts = SrcVT.getVectorNumElements();
 
   if (all_of(Mask, [](int Elem) { return Elem == 0; }) &&
       VT.isScalableVector()) {
@@ -3475,6 +3474,7 @@
   // for targets that support a SPLAT_VECTOR for non-scalable vector types.
   assert(!VT.isScalableVector() && "Unsupported scalable vector shuffle");
 
+  unsigned SrcNumElts = SrcVT.getVectorNumElements();
   unsigned MaskNumElts = Mask.size();
 
   if (SrcNumElts == MaskNumElts) {