RFR: 8247281: migrate ObjectMonitor::_object to OopStorage [v2]

[Roman Kennke]

On Mon, 14 Sep 2020 13:48:25 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> @rkennke - Thanks for the review. I believe @fisk is going to address
> your comments.

Actually, if I understand it correctly, OopStorage already gives us full barriers, so we should be covered, and we can
simply revert JDK-8251451: http://cr.openjdk.java.net/~rkennke/8247281-shenandoah.patch
(Is there a better way to propose amendments to a PR?!)

I believe this probably also means that we don't need to scan object monitor lists during thread-scans, and let SATB
(or whatever concurrent marking) take care of it. @fisk WDYT?

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

PR: https://git.openjdk.java.net/jdk/pull/135