RFR: Update remembered set during old generation mark

[Zhengyu Gu]

On Wed, 14 Apr 2021 21:15:10 GMT, earthling-amzn <github.com+71722661+earthling-amzn at openjdk.org> wrote:

> This change is to support the concurrent remembered set scanning work which is in progress.

src/hotspot/share/gc/shenandoah/shenandoahMark.inline.hpp line 278:

> 276:       // Old mark, found a young pointer.
> 277:       assert(ShenandoahHeap::heap()->is_in_young(obj), "Expected young object.");
> 278:       ShenandoahHeap::heap()->mark_card_as_dirty((HeapWord*)p);

Just a nit, please use cast_from_oop<HeapWord*>(p) instead.

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

PR: https://git.openjdk.java.net/shenandoah/pull/31