[LegalizeTypes] Use getShiftAmountConstant in SplitInteger. (llvm#158392)

This function contained old code for handling the case that the type
returned getScalarShiftAmountTy can't hold the shift amount.

These days this is handled by getShiftAmountTy which is used by
getShiftAmountConstant.

Author: topperc

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp

@@ -1026,14 +1026,9 @@ void DAGTypeLegalizer::SplitInteger(SDValue Op,
   assert(LoVT.getSizeInBits() + HiVT.getSizeInBits() ==
          Op.getValueSizeInBits() && "Invalid integer splitting!");
   Lo = DAG.getNode(ISD::TRUNCATE, dl, LoVT, Op);
-  unsigned ReqShiftAmountInBits =
-      Log2_32_Ceil(Op.getValueType().getSizeInBits());
-  MVT ShiftAmountTy =
-      TLI.getScalarShiftAmountTy(DAG.getDataLayout(), Op.getValueType());
-  if (ReqShiftAmountInBits > ShiftAmountTy.getSizeInBits())
-    ShiftAmountTy = MVT::getIntegerVT(NextPowerOf2(ReqShiftAmountInBits));
-  Hi = DAG.getNode(ISD::SRL, dl, Op.getValueType(), Op,
-                   DAG.getConstant(LoVT.getSizeInBits(), dl, ShiftAmountTy));
+  Hi = DAG.getNode(
+      ISD::SRL, dl, Op.getValueType(), Op,
+      DAG.getShiftAmountConstant(LoVT.getSizeInBits(), Op.getValueType(), dl));
   Hi = DAG.getNode(ISD::TRUNCATE, dl, HiVT, Hi);
 }