RFR(s): 8178363: Incorrect check for nmethod re-registration in C1

Rickard Bäckman rickard.backman at oracle.com
Wed Apr 12 06:40:31 UTC 2017


Looks good.

On 04/10, Per Liden wrote:
> Hi Stefan,
> 
> On 2017-04-10 09:31, Stefan Karlsson wrote:
> >On 2017-04-10 09:05, Per Liden wrote:
> >>Hi,
> >>
> >>When an nmethod is compiled, it's registered with the heap if
> >>ScavengeRootsInCode is non-zero (which it always is). However, during
> >>code patching in C1 we re-register the nmethod with the heap only if it
> >>also has scavengable oops. This additional requirement is only valid for
> >>calls to CodeCache::add_scavenge_root_nmethod(), and not for
> >>CollectedHeap::register_nmethod(). This happens to work today since G1's
> >>is_scavengable() basically always returns true.
> >>
> >>Bug: https://bugs.openjdk.java.net/browse/JDK-8178363
> >>Webrev: http://cr.openjdk.java.net/~pliden/8178363/webrev.0/
> >>Testing: jprt
> >
> >Looks good, from a GC perspective.
> 
> Thanks for reviewing!
> 
> >
> >For non-G1 GCs, we now, unnecessarily, take the CodCache lock and call
> >find_nmethod even when mirror and appendix are non-scavengable. Maybe
> >this should be reviewed on hotspot-comp-dev as well?
> 
> Sure, adding comp-dev.
> 
> thanks,
> Per
> 
> >
> >Thanks,
> >StefanK
> >
> >>
> >>cheers,
> >>Per

/R


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