RFR: 8344640: GenShen: Reuse existing card mark barrier function when dropping references

[Y. Srinivas Ramakrishna]

On Wed, 20 Nov 2024 19:24:56 GMT, William Kemper <wkemper at openjdk.org> wrote:

> When GenShen drops references during concurrent weak reference processing, it manipulates pointers in a list that is threaded through java objects and so must go through the card mark barrier. This change has it reuse an existing function for this purpose.
> 
> ## Testing
> 
> Ran this through internal pipelines: Dacapo, Extremem, SpecJBB2015, SpecJVM2008, Heapothesys (with and without GC stress flags).

good catch and cleanup.

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Marked as reviewed by ysr (Committer).

PR Review: https://git.openjdk.org/shenandoah/pull/547#pullrequestreview-2449947029