RFR: 8366888: C2: incorrect assertion predicate with short running long counted loop [v4]

[Benoît Maillard]

On Thu, 13 Nov 2025 16:28:43 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> src/hotspot/share/opto/loopnode.cpp line 1196:
>> 
>>> 1194: //     for (int = 0; i < stop - start; i+= stride) { ... }
>>> 1195: // Template Assertion Predicates added so far were with an init value of start. They need to be updated with the new
>>> 1196: // init value of 0:
>> 
>> Not being super familiar with assertion predicates, I was a little bit confused at first. I would maybe add something along the lines of:
>> 
>> Suggestion:
>> 
>> // init value of 0. We want the OpaqueLoopInit node on the zero in order to be able to replace it when cloning the predicate.
>> 
>> 
>> But feel free to ignore if you think this is obvious.
>
> Thanks for having a look at this. Does the updated comment look good to you?

Yes, this works for me, thanks!

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

PR Review Comment: https://git.openjdk.org/jdk/pull/27250#discussion_r2527437488