diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -15853,11 +15853,10 @@
 SDValue DAGCombiner::visitFP_ROUND(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
-  ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
   EVT VT = N->getValueType(0);
 
   // fold (fp_round c1fp) -> c1fp
-  if (N0CFP)
+  if (isa<ConstantFPSDNode>(N0))
     return DAG.getNode(ISD::FP_ROUND, SDLoc(N), VT, N0, N1);
 
   // fold (fp_round (fp_extend x)) -> x