RFR: 8347499: C2: Make `PhaseIdealLoop` eliminate more redundant safepoints in loops [v3]

[Roland Westrelin]

On Tue, 16 Sep 2025 05:51:43 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Qizheng Xing has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Improve documentation comments
>
> src/hotspot/share/opto/loopnode.cpp line 3840:
> 
>> 3838: //     inside any nested loop, then that loop is okay
>> 3839: //  E) Otherwise, if an outer loop's ncsfpt on the idom-path is nested in
>> 3840: //     an inner loop, we need to prevent the inner loop from deleting it
> 
> Nice, that's indeed an improvement :)

It would be nice to make sure all cases here have an IR test which is not the case AFAICT. Can you open a JBS issue for that?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/23057#discussion_r2465947623