jdk11.0.2+9 G1BarrierSetC2::eliminate_gc_barrier JVM crash

[Lee Harland]

Hi - i'd encountered this error while running Adopt Java9+ and posted it on
the adopt github and they suggested I post it here. Link to the specific
test case i made
https://github.com/AdoptOpenJDK/openjdk-build/issues/967#issuecomment-514122684

apologies if wrong list or not enough info etc, just doing what i was told
:)

cheers