RFR (S): 8185141: Generalize scavengeable nmethod root handling

[Thomas Schatzl]

Hi Erik,

On Fri, 2017-10-13 at 14:23 +0200, Erik Österlund wrote:
> Hi Thomas,
> 
> Thank you for having a look at this change.
> 
[...]
> > While I agree what you are saying here, given a constraint that
> > CodeCache::_scavenge_root_nmethods needs to stay where it is, the
> > alternative would be the suggestion to move out
> > CodeCache::_scavenge_root_nmethods to GenCollectedHeap.
> > 
> > (Yeah, I know that G1 inherits from GenCollectedHeap right now...)
> 
> It would be unfortunate for collectors that do not want to be part of
> the GenCollectedHeap framework to be unable to use the normal
> scavenge root list I think.
> 
> Eventually, the list probably ought to be completely moved out to its
> own class, possibly with a new better data structure.
> 
> Would you be okay with leaving the actual list in CodeCache for now?
> For this change, my only intention was cleaning up the interface so
> that GC-specific code is not scattered in the shared code, and a GC
> may choose strategy for its scavengeable roots.

Sure, I already indicated so. Ship it.

Thanks,
  Thomas