RFR: 8376839: GenShen: Improve performance of evacuations into the old generation [v4]

[Kelvin Nilsen]

On Mon, 9 Feb 2026 22:43:06 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> When GenShen evacuates an object into the old generation, it also dirties the card for that object and updates the offsets of the first and last object in the card. In many cases, the same card may dirtied repeatedly and the object starts updated unnecessarily. We can reduce the total amount of work by moving these operations into a separate phase of the cycle which allows them to be batched.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Avoid update call when there is no work to be done

Thanks for pulling this together.  I think it is a very valuable improvement.

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Marked as reviewed by kdnilsen (Committer).

PR Review: https://git.openjdk.org/jdk/pull/29511#pullrequestreview-3776290826