[llvm] [SelectionDAG] Add PARTIAL_REDUCE_U/SMLA ISD Nodes (PR #125207)

[Paul Walker via llvm-commits]

================
@@ -4435,6 +4448,12 @@ SDValue DAGTypeLegalizer::SplitVecOp_VECTOR_HISTOGRAM(SDNode *N) {
                                 MMO, IndexType);
 }
 
+SDValue DAGTypeLegalizer::SplitVecOp_PARTIAL_REDUCE_MLA(SDNode *N) {
+  SDValue Res = TLI.expandPartialReduceMLA(N, DAG);
+  ReplaceValueWith(SDValue(N, 0), Res);
+  return SDValue();
----------------
paulwalker-arm wrote:

Does just `return TLI.expandPartialReduceMLA(N, DAG)` work here?

https://github.com/llvm/llvm-project/pull/125207