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

[Coleen Phillimore]

On Fri, 11 Sep 2020 21:42:08 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.
>
> Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:
> 
>   coleenp CR - changes to resolve Coleen's comments.

I approve of this without seeing any new changes.

src/hotspot/share/runtime/thread.cpp line 4593:

> 4591:   // are used in om_flush().
> 4592:   BarrierSet::barrier_set()->on_thread_detach(p);
> 4593:

One last question, that doesn't require a comment why it's here, but why was this moved?

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

Marked as reviewed by coleenp (Reviewer).

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