RFR: 8333840: C2 SuperWord: wrong result for MulAddS2I when inputs permuted [v5]

[Emanuel Peter]

On Thu, 13 Jun 2024 14:31:25 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/superword.cpp line 2851:
>> 
>>> 2849: }
>>> 2850: 
>>> 2851: Node_List* PackSet::strided_pack_input_at_index_or_null(const Node_List* pack, const int index, const int stride, const int offset) const {
>> 
>> Do you plan to use this method at other places as well? Otherwise, you could hardcode `stride = 2` in the context of `MulAddS2I`.
>
> Yes, I plan to use it with `stride = 1` and `offset = 0`. That would be a normal input pack. I will refactor in a future RFE.

This would be it:

  Node_List* pack_input_at_index_or_null(const Node_List* pack, const int index) const {
    return strided_pack_input_at_index_or_null(pack, index, 1, 0);
  }

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PR Review Comment: https://git.openjdk.org/jdk/pull/19619#discussion_r1638334774