[LegalizeTypes][NFC] Use dyn_cast instead of isa and cast.

[Jimerlife]

Summary

Use dyn_cast<> instead of isa<> and cast<>

[craig.topper]

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

3036–3037

There shouldn't be a space before Index

[Jimerlife]

address comment

[Jimerlife]

update and add const keyword

[craig.topper]

LGTM

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

SDValue DAGTypeLegalizer::SplitVecOp_EXTRACT_SUBVECTOR(SDNode *N) {
   }
 }
 
 SDValue DAGTypeLegalizer::SplitVecOp_EXTRACT_VECTOR_ELT(SDNode *N) {
   SDValue Vec = N->getOperand(0);
   SDValue Idx = N->getOperand(1);
   EVT VecVT = Vec.getValueType();
 
-  if (isa<ConstantSDNode>(Idx)) {
-    uint64_t IdxVal = cast<ConstantSDNode>(Idx)->getZExtValue();
+  if (const ConstantSDNode *Index = dyn_cast<ConstantSDNode>(Idx)) {
+    uint64_t IdxVal = Index->getZExtValue();
 
     SDValue Lo, Hi;
     GetSplitVector(Vec, Lo, Hi);
 
     uint64_t LoElts = Lo.getValueType().getVectorMinNumElements();
 
     if (IdxVal < LoElts)
       return SDValue(DAG.UpdateNodeOperands(N, Lo, Idx), 0);