RFR: 8333457: GenShen: Move remembered set into new generational code [v2]

[William Kemper]

On Tue, 4 Jun 2024 01:19:08 GMT, Y. Srinivas Ramakrishna <ysr at openjdk.org> wrote:

>> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix typo in comment
>
> src/hotspot/share/gc/shenandoah/shenandoahMark.inline.hpp line 330:
> 
>> 328:       // Old mark, found a young pointer.
>> 329:       // TODO:  Rethink this: may be redundant with dirtying of cards identified during young-gen remembered set scanning
>> 330:       // and by mutator write barriers.  Assert
> 
> I assume "Assert" here meant: "Assert card is dirty, instead of marking it."
> Would be worth doing that. It makes sense that this card dirtying is redundant, since no old card mark has been cleared that needs to be remarked, nor is a new cross-gen pointer being created here.
> 
> May be we need a ticket to get rid of this separately.

This assert passes tier1. I'll run it through the full pipeline and see if it pops. If this code turns out to be redundant, I'd remove it on a different PR.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/443#discussion_r1626479801