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

[Sander de Smalen via llvm-commits]

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@@ -2881,6 +2890,13 @@ SDValue DAGTypeLegalizer::PromoteIntOp_VECTOR_FIND_LAST_ACTIVE(SDNode *N,
   return SDValue(DAG.UpdateNodeOperands(N, NewOps), 0);
 }
 
+SDValue DAGTypeLegalizer::PromoteIntOp_PARTIAL_REDUCE_MLA(SDNode *N,
+                                                          unsigned OpNo) {
+  SmallVector<SDValue, 1> NewOps(N->ops());
+  NewOps[OpNo] = GetPromotedInteger(N->getOperand(OpNo));
+  return SDValue(DAG.UpdateNodeOperands(N, NewOps), 0);
+}
+
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sdesmalen-arm wrote:

I actually forgot to leave a comment about that, because I added an assert to test that OpNo > 1 when I checked out this patch locally, and found no failures, so OpNo = 0 should indeed be promoted as part of the result lowering.

Are you suggesting both operands need updating at the same time? (this function is otherwise called for both OpNo=1 and OpNo=2)

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