[GR-45919] Generational ZGC Support for Graal JIT

[PhantomG27249]

Feature request
With release of jdk 21 came support for generational zgc. It offers substantial performance improvements over single generation zgc. The graal jit currently supports single generation zgc. It would be a very welcome performance enhancement if generational zgc was supported. It offers extreme resistance to high pause times along with excellent allocation performance and lower overhead.

Is your feature request related to a problem? Please describe.
Single generation zgc has comparable high overhead relative to generational collectors but has desirable performance characteristics.

Describe the solution you'd like.
Support for generational zgc with the graalvm jit. Enables low overhead high allocation low pause time garbage collection with the performance gains of graal jit.

Describe who do you think will benefit the most.
GraalVM users.

Describe alternatives you've considered.
-Continue to only support single generation zgc
-Support for generational Shenandoah

Additional context.
JEP 439: https://openjdk.org/jeps/439

Express whether you'd like to help contributing this feature
I am not familiar enough with graalvm's internals to be useful with this but would be happy to help test builds if there are any.

[fniephaus]

Thanks for raising this feature request, @PhantomG27249 . We've added #8117 to our roadmap. Feel free to subscribe to the ticket to stay updated on support for Generational ZGC in Graal.