Cherry-picks from jdk/jdk to shenandoah/jdk

[Roman Kennke]

Looks ok. Tomorrow I would have picked it up anyway.

Roman


> Hi,
> 
> I would like to cherry pick following changes from jdk/jdk to
> shenandoah/jdk, as they are needed for x86_32 nmethod barrier and
> concurrent class unloading work.
> 
> Cherry-pick 8231250: Shenandoah: Traversal GC should keep alive weak
> load from heap
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/JDK-8231250/webrev.00/
> 
> Cherry-pick 8231410: Shenandoah: clone barrier should use base pointer
> Cherry-pick 8231447: Shenandoah: Compilation-time regression after
>                      JDK-8231086
> Cherry-pick 8231499: Shenandoah: compiler/arraycopy
>                      /TestDefaultMethodArrayCloneDeoptC2 fails
> http://cr.openjdk.java.net/~zgu/shenandoah/JDK-8231499/webrev.00/
> 
> Test:
>   hotspot_gc_shenandoah Linux x86_64 and x86_32
> 
> Thanks,
> 
> -Zhengyu
> 
> 
> 
>