RFR: 8367347: Serial: Refactor CLDScanClosure [v4]

[Stefan Karlsson]

On Wed, 10 Sep 2025 19:38:14 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

>> Refactor `CLDScanClosure` so that all CLD logic is encapsulated in the CLD closure, without polluting the oop closure.
>> 
>> Test: tier1-2, running tier3
>
> Francesco Andreuzzi has updated the pull request incrementally with one additional commit since the last revision:
> 
>   inline

Looks good to me. FWIW, in this and in Albert's previous patch I had to check `is_in_young_gen` to see if it was a trivial check and not something complicated. We could make it easier for the readers if this code:

        if (is_in_young_gen(new_obj) && !_has_oops_into_young_gen) {
          _has_oops_into_young_gen = true;
        }

to:

        if (!_has_oops_into_young_gen && is_in_young_gen(new_obj)) {
          _has_oops_into_young_gen = true;
        }

It might also be nicer to the branch predictor.

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Marked as reviewed by stefank (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27199#pullrequestreview-3209146296