This bug tracks the investigation of a crash reported on the hotspot-zgc-dev list:
http://mail.openjdk.java.net/pipermail/zgc-dev/2019-August/000719.html

# SIGSEGV (0xb) at pc=0x00007f2f279f1447, pid=12048, tid=12082
#
# JRE version: OpenJDK Runtime Environment (11.0.3+12) (build 11.0.3+12-b304.10)
# Java VM: OpenJDK 64-Bit Server VM (11.0.3+12-b304.10, mixed mode, tiered, z gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0xdd2447] LoadBarrierNode::has_dominating_barrier(PhaseIdealLoop*, bool, bool)+0x567

Current CompileTask:
C2:28363487 218236 4 com.intellij.psi.impl.source.JavaLightStubBuilder::isCodeBlockWithoutStubs (55 bytes)

Stack: [0x00007f2ed67ff000,0x00007f2ed6900000], sp=0x00007f2ed68fa050, free space=1004k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xdd2447] LoadBarrierNode::has_dominating_barrier(PhaseIdealLoop*, bool, bool)+0x567
V [libjvm.so+0xdd270d] LoadBarrierNode::Ideal(PhaseGVN*, bool)+0x13d
V [libjvm.so+0xbfaa35] PhaseIterGVN::transform_old(Node*)+0xb5
V [libjvm.so+0xbf829c] PhaseIterGVN::optimize()+0x1ac
V [libjvm.so+0xa5e1fc] PhaseIdealLoop::build_and_optimize(bool, bool, bool)+0xe2c
V [libjvm.so+0xdd8c6f] ZBarrierSetC2::find_dominating_barriers(PhaseIterGVN&)+0x19f
V [libjvm.so+0x63d540] Compile::Optimize()+0x15e0
V [libjvm.so+0x63e56c] Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0xfcc
V [libjvm.so+0x568566] C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0xe6
V [libjvm.so+0x6483fb] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x3fb
V [libjvm.so+0x6498b8] CompileBroker::compiler_thread_loop()+0x548
V [libjvm.so+0xd39328] JavaThread::thread_main_inner()+0xf8
V [libjvm.so+0xd395d8] JavaThread::run()+0x268
V [libjvm.so+0xd359b6] Thread::call_run()+0x146
V [libjvm.so+0xba3468] thread_native_entry(Thread*)+0xf8