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

[Sander de Smalen via llvm-commits]

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@@ -6139,6 +6154,12 @@ SDValue DAGTypeLegalizer::PromoteIntRes_VECTOR_FIND_LAST_ACTIVE(SDNode *N) {
   return DAG.getNode(ISD::VECTOR_FIND_LAST_ACTIVE, SDLoc(N), NVT, N->ops());
 }
 
+SDValue DAGTypeLegalizer::PromoteIntRes_PARTIAL_REDUCE_MLA(SDNode *N) {
+  SDValue Res = DAG.expandPartialReduceMLA(N);
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sdesmalen-arm wrote:

I'm actually a bit surprised that this works, because I would have expected some error to be emitted if the returned node wouldn't have a legal return type. Like with `PromoteIntOp_PARTIAL_REDUCE_MLA`, I think this should just promote the result type (and with that, also the first operand of the node).

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