RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v8]

[Stefan Karlsson]

On Fri, 13 Sep 2024 12:47:09 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Which ones are remaining? JDK-8337709 implemented the same change for G1 GC before JDK-8311163.
>> 
>> The full collectors/g1 marking do not modify the length fields but have multiple separate queues which is a different issue. It will also be handled by the new `PartialArrayTaskStepper`, but should be of no concern here.
>> 
>> If I am not missing some case, this whole method is unnecessary now.
>
> If you've already fixed this for GC then I agree that we could remove this.

This seems like something that should be done as a separate patch that gets pushed before this PR.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1758808115