RFR 8210856: Move InstanceKlass DependencyContext cleaning to SystemDictionary::do_unloading()

[Erik Osterlund]

Hi Coleen,

Thank you for sorting this out. Looks good.

Thanks,
/Erik

> On 21 Sep 2018, at 11:45, coleen.phillimore at oracle.com wrote:
> 
> Summary: Already walk classes in ClassLoaderData::unload so generalize to also clean nmethod dependencies.
> 
> The nmethod dependencies should be cleaned before metadata is purged.  See bug for more details.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/8210856.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8210856
> 
> Tested with hs tier1-7, modified gtest, and compiler/codecache/stress/RandomAllocationTest.java from bug https://bugs.openjdk.java.net/browse/JDK-8143408.
> 
> Thanks,
> Coleen
> 
>