RFR: 8247281: migrate ObjectMonitor::_object to OopStorage

[Erik Österlund]

On Fri, 11 Sep 2020 18:45:28 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> This RFE is to migrate the following field to OopStorage:
> 
> class ObjectMonitor {
> <snip>
>   void* volatile _object; // backward object pointer - strong root
> 
> Unlike the previous patches in this series, there are a lot of collateral
> changes so this is not a trivial review. Sorry for the tedious parts of
> the review. Since Erik and I are both contributors to this patch, we
> would like at least 1 GC team reviewer and 1 Runtime team reviewer.
> 
> This changeset was tested with Mach5 Tier[1-3],4,5,6,7,8 testing
> along with JDK-8252980 and JDK-8252981. I also ran it through my
> inflation stress kit for 48 hours on my Linux-X64 machine.

This looks great Dan. I like your addition of is_chainmarker() - it makes this step a lot better, without having any
special oops that are not oops. Thanks for sorting this out!

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

Marked as reviewed by eosterlund (Reviewer).

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