RFR: 8325541: C2 SuperWord: refactor filter / split [v2]

[Emanuel Peter]

On Fri, 9 Feb 2024 15:18:52 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/superword.cpp line 582:
>> 
>>> 580: 
>>> 581:   // Now we only remove packs:
>>> 582:   construct_my_pack_map();
>> 
>> `construct_my_pack_map()` also asserts that each node is only in one pack after `combine_packs()`. Maybe we should move this code directly to `combine_packs()` as a post-condition. 
>> 
>> This was already like this before, but it seems like "my" in `_my_pack` in `SWNodeInfo` is redundant and could just be renamed to `_pack`. Then we could also rename this method to something like `map_nodes_to_packs()`. But this exceeds the scope of this PR and could also be done separately if you agree with this suggestion.
>
> I can do that in a future RFE. I hope that the `_packset` and `_my_pack` eventually can become its own class. Then I can rename things everywhere.

[JDK-8325252](https://bugs.openjdk.org/browse/JDK-8325252) C2 SuperWord: refactor the packset

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PR Review Comment: https://git.openjdk.org/jdk/pull/17785#discussion_r1484463748