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

[David Holmes]

On Fri, 11 Sep 2020 21:45:08 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.

Overall cleanup looks good. More complicated than I had expected, but then this changes the GC races with the deflation
code.

Not sure about the JVM TI changes!

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