Run test with:

-Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive -XX:+VerifyOops -Xcomp TestJNIGlobalRefs

Crash with:
# fatal error: DEBUG MESSAGE: verify_oop: rax: broken oop

I chased down a bit, the verify_oop() came from:

src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp#861