[master] Withdrawn: Unconditionally preserve all marks during GC

[Roman Kennke]

On Tue, 18 May 2021 20:54:54 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> When storing the Klass* in the object header, we need to preserve all marks during GC, because otherwise we'd be loosing the Klass*.
> 
> This means that the PreservedMarks structure is repurposed as a full (reverse) forwarding table. Reverse because instead of mapping object->forwardee, and leaving the mark alone, it maps object->mark and stores the forwardee in the header, which might be a better idea because it means we can have a most compact table.
> 
> Shenandoah doesn't have this problem, except during full-GC, and ZGC has its own forwarding table.
> 
> This change will likely affect performance, but I haven't checked by how much, yet. It's probably more useful to see this in the context of actually reduced header.
> Testing:
>  - [x] tier1
>  - [x] tier2

This pull request has been closed without being integrated.

-------------

PR: https://git.openjdk.java.net/lilliput/pull/6