RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v11]

[Paul Hohensee]

On Tue, 26 Nov 2024 00:37:32 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> This PR merges JEP 404, a generational mode for the Shenandoah garbage collector. The JEP can be viewed here: https://openjdk.org/jeps/404. We would like to target JDK24 with this PR.
>
> William Kemper has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'shenandoah/master' into great-genshen-pr-redux
>  - 8344985: GenShen: Refactor arraycopy barrier for generational mode
>    
>    Reviewed-by: shade

Marked as reviewed by phh (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/21273#pullrequestreview-2466068316