[LegalizeTypes][VP] Fix OpNo in WidenVecOp_VP_SCATTER

[Jimerlife]

Summary

Fix OpNo in WidenVecOp_VP_SCATTER. When widen index, the OpNo should be 3.
VPScatterSDNode (Chain, value, base, index, scale, mask, vlen)

[craig.topper]

LGTM

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

SDValue DAGTypeLegalizer::WidenVecOp_VP_SCATTER(SDNode *N, unsigned OpNo) {
 
   if (OpNo == 1) {
     DataOp = GetWidenedVector(DataOp);
     Index = GetWidenedVector(Index);
     const auto WideEC = DataOp.getValueType().getVectorElementCount();
     Mask = GetWidenedMask(Mask, WideEC);
     WideMemVT = EVT::getVectorVT(*DAG.getContext(),
                                  VPSC->getMemoryVT().getScalarType(), WideEC);
-  } else if (OpNo == 4) {
+  } else if (OpNo == 3) {
     // Just widen the index. It's allowed to have extra elements.
     Index = GetWidenedVector(Index);
   } else
     llvm_unreachable("Can't widen this operand of mscatter");
 
   SDValue Ops[] = {
       VPSC->getChain(),       DataOp, VPSC->getBasePtr(), Index, Scale, Mask,
       VPSC->getVectorLength()};