RFR: 8353290: C2: Refactor PhaseIdealLoop::is_counted_loop() [v28]

[Kangcheng Xu]

On Fri, 16 Jan 2026 16:16:04 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> @chhagedorn Sorry I made a mistake with safepoint detection. Upon inspecting the original code, `_safepoint` should be set to `null` if `.opcode() != Op_SafePoint`. This logic is missing from my refactored code. How the test only fails with `-XX:+UseSerialGC` is beyond me.
>> 
>>> I will check next week if I can extract a reproducer to share.
>> Yes it is curious regarding the diff assert. I'll appreciate if you can share more information. Thank you very much!
>
> Thanks for addressing the issue @tabjy! Unfortunately, the closed test triggering the DIFF assert uses a closed jar that cannot be shared and does not provide source information. I will try to have a look myself at the failure and report back what I found next week.

Understood. Thank you for looking into it @chhagedorn! I really appreciate it!

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PR Comment: https://git.openjdk.org/jdk/pull/24458#issuecomment-3761710121