RFR: 8325155: C2 SuperWord: remove alignment boundaries [v2]

[Emanuel Peter]

On Mon, 27 May 2024 14:31:48 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 25 commits:
>> 
>>  - Merge branch 'master' into JDK-8325155-rm-alignment-boundaries
>>  - rm TODO
>>  - manual merge
>>  - revert a line, need to fix it different
>>  - improve comments
>>  - fix alignment
>>  - fix reductions
>>  - MaxI reduction over chars
>>  - Merge branch 'master' into JDK-8325155-rm-alignment-boundaries
>>  - Merge branch 'master' into JDK-8325155-rm-alignment-boundaries
>>  - ... and 15 more: https://git.openjdk.org/jdk/compare/c4867c62...82c9a77a
>
> src/hotspot/share/opto/superword.cpp line 2790:
> 
>> 2788:   }
>> 2789: 
>> 2790:   if (!is_velt_basic_type_compatible_use_def(use, u_idx)) {
> 
> Might be easier to directly put in `def` as defined on L2764 instead of passing the index to the def.

Good point. I think I used to require `idx` in a previous iteration, but not any more!

> src/hotspot/share/opto/superword.cpp line 2816:
> 
>> 2814: }
>> 2815: 
>> 2816: bool SuperWord::is_velt_basic_type_compatible_use_def(Node* use, int idx) const {
> 
> Maybe add a comment here to quickly explain that compatible means "output size of the def node matches the input size of the use node".

Good idea!

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/18822#discussion_r1617626973
PR Review Comment: https://git.openjdk.org/jdk/pull/18822#discussion_r1617628690