RFR: Upstream merge to jdk-12+19

[Roman Kennke]

And of course, the obligatory list of changes:

http://cr.openjdk.java.net/~rkennke/upstream-jdk12-merge-2018-11-08/outgoing.txt

The new baseline would be:

changeset:   53243:dc1f9dec2018
user:        rkennke
date:        Wed Nov 07 20:24:44 2018 +0100
summary:     8213469: Remove/fix leftovers from JDK-8213384: Move G1/C2
barrier verification into G1BarrierSetC2

Ok?

> Lots of good stuff from upstream:
> 
> - 8212610: Fix handling of memory in PhaseIdealLoop::clone_loop_predicates()
> - 8212243: More gc interface tweaks for arraycopy
> - 8213384: Move G1/C2 barrier verification into G1BarrierSetC2
> - 8213381: Hook to allow GC to inject Node::Ideal() calls
> - 8213371: GC/C2 abstraction and cleanup to handle custom offset for GC
> memory accesses
> - 8213469: Remove/fix leftovers from JDK-8213384: Move G1/C2 barrier
> verification into G1BarrierSetC2
> 
> all of which amounts to much-reduced upstream diff in C2 land.
> 
> Testing: tier3_gc_shenandoah fastdebug/release (x86)
> (might need extra testing on aarch64 because we had some conflicts there
> in the various CAS matchers in C2)
> 
> I needed to add this to shenandoahCodeRoots.cpp:
> diff --git a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
> b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
> @@ -205,6 +205,7 @@
>        break;
>      }
>      case 2: {
> +      ResourceMark rm;
>        ShenandoahNMethodOopDetector detector;
>        nm->oops_do(&detector, /* allow_zombie = */ true);
> 
> 
> 
> Because of ShenandoahNMethodOopDetector allocating a GrowableArray as
> resource. Not sure why this started failing now, and not earlier and if
> needs backporting.
> 
> Ok?
> 
> Roman
>