RFR (M) 8249768: Move static oops and NullPointerException oops from Universe into OopStorage

[David Holmes]

Hi Coleen,

cc'ing serviceability due to SA changes.

On 21/07/2020 6:53 am, coleen.phillimore at oracle.com wrote:
> Summary: Move static oops into OopStorage and make NPE oops an objArrayOop.
> 
> I've broken up moving oops in Universe to OopStorage into several 
> parts.  This change moves the global static oops.  These OopHandles are 
> not released.

Overall looks good. But two things ...

1. naming

!   // preallocated error objects (no backtrace)
!   static OopHandle    _out_of_memory_error;

     // array of preallocated error objects with backtrace
!   static OopHandle     _preallocated_out_of_memory_error_array;

Both of these are pre-allocated arrays of OopHandles, differing only in 
whether the underlying OOME has a backtrace or not. I find the newly 
introduced _out_of_memory_error unclear in that regard. At a minimum 
could _out_of_memory_error become _out_of_memory_errors ? But ideally 
can we name these two arrays in a more distinguishable way?

2. SA

You've simply deleted all the SA/vmstructs code that referenced the oops 
that are no longer present. Does the SA not care about these things and 
need access to them? (I don't know hence cc to serviceability folk.)

Thanks,
David
-----

> This has been tested with tier1-3 and on also remote-build -b 
> linux-arm32,linux-ppc64le-debug,linux-s390x-debug,linux-x64-zero.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/2020/8249768.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8249768
> 
> Thanks,
> Coleen