RFR: 8373116: Genshen: arraycopy_work should be always done for arrays in old gen during young concurrent marking [v7]

[Kelvin Nilsen]

On Mon, 8 Dec 2025 22:32:49 GMT, Xiaolong Peng <xpeng at openjdk.org> wrote:

>> There is one case, I think we may not want to make the test here overly complicated so I didn't add it:
>> (!A && B && C && !D) 
>> 
>> It could happen after final-mark in bootstrap young GC, the young marking has done, old marking is in progress.
>
> I have updated PR, now is_generational is passed to the method as template parameter.

When marking OLD and not marking YOUNG, there is no need to enforce SATB on array_copy if the destination resides in young.  That is because such an array would essentially reside above the old-generation marking TAMS.

I understand that we may choose to be a bit less aggressive in how much we optimize for improved code clarity.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28669#discussion_r2600717666