The VM crashes during heap dump because of lack of support for flat arrays.

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home.local/fred/WORK/Valhalla/GitRepos/valhalla/open/src/hotspot/share/services/heapDumper
.cpp:735), pid=1833891, tid=1833898
# Error: ShouldNotReachHere()
#
# JRE version: Java(TM) SE Runtime Environment (17.0) (fastdebug build 17-lworld3ea+0-2021-05-07-1433318.fred.
..)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 17-lworld3ea+0-2021-05-07-1433318.fred..., mixed mode,
 sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0xe060ee] DumperSupport::sig2size(Symbol*)+0x7e
#
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimite
d" before starting Java again
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: PressEnter

Host: dalk, Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz, 16 cores, 31G, Ubuntu 20.04.2 LTS
Time: Tue May 25 10:22:10 2021 EDT elapsed time: 26.314957 seconds (0d 0h 0m 26s)

--------------- T H R E A D ---------------

Current thread (0x00007f9280248010): VMThread "VM Thread" [stack: 0x00007f9246700000,0x00007f9246800000] [id=
1833898]

Stack: [0x00007f9246700000,0x00007f9246800000], sp=0x00007f92467fe5f0, free space=1017k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xe060ee] DumperSupport::sig2size(Symbol*)+0x7e
V [libjvm.so+0xe0631a] DumperSupport::instance_size(Klass*) [clone .constprop.0]+0x1da
V [libjvm.so+0xe0d335] DumperSupport::dump_class_and_array_classes(DumpWriter*, Klass*)+0x205
V [libjvm.so+0x9f1e0d] ClassLoaderData::classes_do(KlassClosure*)+0x3d
V [libjvm.so+0x9fd35d] ClassLoaderDataGraph::classes_do(KlassClosure*)+0x1bd
V [libjvm.so+0xe0ac5f] VM_HeapDumper::work(unsigned int) [clone .part.0]+0xdf
V [libjvm.so+0x1afbcaf] WorkGang::run_task(AbstractGangTask*, unsigned int, bool)+0x13f
V [libjvm.so+0xe04b9c] VM_HeapDumper::doit()+0x16c
V [libjvm.so+0x1a8cfaa] VM_Operation::evaluate()+0x18a
V [libjvm.so+0x1ab02a3] VMThread::evaluate_operation(VM_Operation*)+0x183
V [libjvm.so+0x1ab0f18] VMThread::inner_execute(VM_Operation*)+0x1f8
V [libjvm.so+0x1ab1155] VMThread::loop()+0xb5
V [libjvm.so+0x1ab1287] VMThread::run()+0xc7
V [libjvm.so+0x1997520] Thread::call_run()+0x100
V [libjvm.so+0x164349e] thread_native_entry(Thread*)+0x10e