hg: jdk/sandbox: 8251359: Shenandoah: filter null oops before calling enqueue/SATB barrier

[chris.hegarty at oracle.com]

Changeset: 99ce8ecc1e32
Author:    zgu
Date:      2020-08-11 14:41 -0400
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/99ce8ecc1e32

8251359: Shenandoah: filter null oops before calling enqueue/SATB barrier
Reviewed-by: shade

! src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
! src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp