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

[Sander de Smalen via llvm-commits]

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@@ -1607,6 +1607,13 @@ class SelectionDAG {
   /// the target's desired shift amount type.
   SDValue getShiftAmountOperand(EVT LHSTy, SDValue Op);
 
+  // Expands PARTIAL_REDUCE_S/UMLA nodes
+  // \p Acc Accumulator for where the result is stored for the partial reduction
+  // operation.
+  // \p Input1 First input for the partial reduction operation
+  // \p Input2 Second input for the partial reduction operation
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sdesmalen-arm wrote:

remove (`Acc`, `Input1` and `Input2` are not parameters to this function).

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