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

[James Chesterman via llvm-commits]

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@@ -3182,6 +3186,11 @@ void DAGTypeLegalizer::SplitVecRes_VP_REVERSE(SDNode *N, SDValue &Lo,
   std::tie(Lo, Hi) = DAG.SplitVector(Load, DL);
 }
 
+void DAGTypeLegalizer::SplitVecRes_PARTIAL_REDUCE_MLA(SDNode *N) {
+  SDValue Res = TLI.expandPartialReduceMLA(N, DAG);
+  ReplaceValueWith(SDValue(N, 0), Res);
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JamesChesterman wrote:

Doing it this way did not change the result of any tests in the end. But I have changed it to doing it this way to make it more similar to what is already done. Thank you for pointing it out.

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