[LegalizeTypes] Use GetSplitVector in SplitVec(Res/Op)_PARTIAL_REDUCE_MLA (#162513)

Using DAG.getSplitVector creates new nodes that need to be legalized. We
should use GetSplitVector to get the already legalized copy of the
inputs.

Author: topperc

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

@@ -3416,7 +3416,7 @@ void DAGTypeLegalizer::SplitVecRes_PARTIAL_REDUCE_MLA(SDNode *N, SDValue &Lo,
   SDValue Input2 = N->getOperand(2);
 
   SDValue AccLo, AccHi;
-  std::tie(AccLo, AccHi) = DAG.SplitVector(Acc, DL);
+  GetSplitVector(Acc, AccLo, AccHi);
   unsigned Opcode = N->getOpcode();
 
   // If the input types don't need splitting, just accumulate into the
@@ -3429,8 +3429,8 @@ void DAGTypeLegalizer::SplitVecRes_PARTIAL_REDUCE_MLA(SDNode *N, SDValue &Lo,
 
   SDValue Input1Lo, Input1Hi;
   SDValue Input2Lo, Input2Hi;
-  std::tie(Input1Lo, Input1Hi) = DAG.SplitVector(Input1, DL);
-  std::tie(Input2Lo, Input2Hi) = DAG.SplitVector(Input2, DL);
+  GetSplitVector(Input1, Input1Lo, Input1Hi);
+  GetSplitVector(Input2, Input2Lo, Input2Hi);
   EVT ResultVT = AccLo.getValueType();
 
   Lo = DAG.getNode(Opcode, DL, ResultVT, AccLo, Input1Lo, Input2Lo);
@@ -4761,8 +4761,8 @@ SDValue DAGTypeLegalizer::SplitVecOp_PARTIAL_REDUCE_MLA(SDNode *N) {
 
   SDLoc DL(N);
   SDValue Input1Lo, Input1Hi, Input2Lo, Input2Hi;
-  std::tie(Input1Lo, Input1Hi) = DAG.SplitVector(N->getOperand(1), DL);
-  std::tie(Input2Lo, Input2Hi) = DAG.SplitVector(N->getOperand(2), DL);
+  GetSplitVector(N->getOperand(1), Input1Lo, Input1Hi);
+  GetSplitVector(N->getOperand(2), Input2Lo, Input2Hi);
   unsigned Opcode = N->getOpcode();
   EVT ResultVT = Acc.getValueType();