RFR [8], 2018-09-10, Bulk backports to sh/jdk8

[Roman Kennke]

Looks good, thank you!

Roman


> http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20180910/webrev.01/
> 
> This backports recent work to sh/jdk8:
> 
>  [backport] Allocation path should not touch GC barriers for metadata
>  [backport] Soft refs should be purged reliably on allocation failure, or with compact heuristics
>  [backport] shenandoah_assert_correct should verify classes before claiming _safe_oop
>  [backport] Tests should use -XX:+ShenandoahVerify in some OOM-evac configurations
>  [backport] Degenerated evacuation
>  [backport] Soft-refs policy needs reliable heap usage data after the GC cycle
>  [backport] Unreachable assert in ShenandoahCodeRoots::acquire_lock
>  [backport] Prune undefined and unused methods
>  [backport] Passive heuristics should enter degen GC, not full GC
>  [backport] Reshuffle tests: verify STW GC is working first, then verify under aggressive, then the rest
>  [backport] TestHeapDump runs much faster with small heap
>  [backport] Cleanup: remove unused root processor's sub tasks
>  [backport] EvilSyncBug test is too slow
>  [backport] Purge partial heuristics and connection matrix infrastructure
>  [backport] Remove NMethodSizeLimit adjustment for Shenandoah
> 
> Testing: hotspot_tier3_gc_shenandoah {fastdebug|release}
> 
> Thanks,
> -Aleksey
>