RFR (S) 8249938: Move mirror oops from Universe into OopStorage

[coleen.phillimore at oracle.com]

Thank you for reviewing, Ioi.

On 7/23/20 4:41 PM, Ioi Lam wrote:
>
>
> On 7/23/20 10:05 AM, coleen.phillimore at oracle.com wrote:
>> Summary: Save and restore mirror oops to temporary array for CDS, and 
>> move them to OopStorage once restored.
>>
>> This is a subtask of moving oops out of Universe.  I ran performance 
>> tested of this and there is no performance change. Some slight 
>> decrease in number of instructions (improvement!) in Perfstartup-Noop 
>> that were flagged as significant - 0.10%
>>
>> Tested with mach5 tier1-3.
>>
>> open webrev at 
>> http://cr.openjdk.java.net/~coleenp/2020/8249938.01/webrev
>> bug link https://bugs.openjdk.java.net/browse/JDK-8249938
>>
>> Thanks,
>> Coleen
>
> Hi Coleen,
>
> The changes looks good. I think Universe::serialize() can be 
> simplified as (not tested):
>
> void Universe::serialize(SerializeClosure* f) {
>
> #if INCLUDE_CDS_JAVA_HEAP
>   {
>     oop mirror_oop;
>     for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
>       if (f->is_reading()) {   // f->reading() ...
>         f->do_oop(&mirror_oop); // read from archive
>         _mirrors[i] = OopHandle(vm_global(), mirror_oop);
>       } else {
>         mirror_oop = _mirrors[i].resolve();
>         f->do_oop(&mirror_oop); // write to archive
>       }
>       if (mirror_oop != NULL) { // may be null if archived heap is 
> disabled
> java_lang_Class::update_archived_primitive_mirror_native_pointers(mirror_oop); 
>
>       }
>     }
>   }
> #endif

Yes that works and is better.  I think GC hates when the location of 
mirror_oop is the same, but serializing doesn't care.  I've rerun tier1 
tests on it and it all passes.
Thanks!
Coleen
>
> Thanks
> - Ioi