RFR: 8342393: Promote commutative vector IR node sharing [v26]

[Jatin Bhateja]

On Mon, 24 Feb 2025 06:31:07 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 20 commits:
>> 
>>  - Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8342393
>>  - Safety assertion added
>>  - Review resolutions
>>  - Lowering feature check to IR annotation level
>>  - Adding missed feature check
>>  - Review comments resolutions.
>>  - Modifed scheme not based over fragile node level flags base solution.
>>  - Updating comments for clarity
>>  - Adding a missed check to skip over commoning of predicated vector operations
>>  - Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8342393
>>  - ... and 10 more: https://git.openjdk.org/jdk/compare/1e87ff01...acb613da
>
> src/hotspot/share/opto/vectornode.cpp line 1101:
> 
>> 1099: 
>> 1100:   // Sort inputs of commutative non-predicated vector operations to help value numbering.
>> 1101:   if (should_swap_inputs_to_help_global_value_numbering()) {
> 
> It reads way too verbose to me.
> 
> I'd just shape it as:
> 
> // Sort inputs of commutative vector operations to help value numbering.
> if (is_commutative()) {
>   if (in(1)->_idx > in(2)->_idx) {
>     swap_edges(1, 2);
>   }
> }

It was modified based on @eme64  suggestion,
https://github.com/openjdk/jdk/pull/22863#discussion_r1942531523

I am inclined to go with what we have to save another approval cycle :-)

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

PR Review Comment: https://git.openjdk.org/jdk/pull/22863#discussion_r1967145676