C2: assert(!in->is_CFG()) failed: CFG Node with no controlling input?

The attached Java Fuzzer test starts to fail after JDK-8264649 (but seems to just reveal an existing issue) with the following assertion failure:

To reproduce:
$ java -Xcomp -XX:-TieredCompilation -XX:CompileOnly=Test Test.java
$ java -Xcomp -XX:-TieredCompilation -XX:CompileOnly=Reduced Reduced.java

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/mach5/mesos/work_dir/slaves/35546316-ed70-4084-8244-d672e7734fd1-S57035/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/41fc080c-d2db-43a6-87b0-daa1149175bc/runs/ea6bcc43-d159-4998-ab37-df1970ab9b47/workspace/open/src/hotspot/share/opto/loopnode.cpp:4763), pid=18026, tid=18040
# assert(!in->is_CFG()) failed: CFG Node with no controlling input?
#
# JRE version: Java(TM) SE Runtime Environment (17.0+28) (fastdebug build 17-ea+28-LTS-2534)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 17-ea+28-LTS-2534, compiled mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x12fef24] PhaseIdealLoop::build_loop_early(VectorSet&, Node_List&, Node_Stack&)+0x6d4
............
Command Line: -Xmx1G -Xcomp -Xbatch -XX:-TieredCompilation -XX:CompileOnly=Test -XX:CompileCommand=quiet Test
............
Current thread (0x00007fd65047fc40): JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=18040, stack(0x00007fd6443cb000,0x00007fd6444cc000)]


Current CompileTask:
C2: 309 8 % b Test::mainTest @ 229 (669 bytes)

Stack: [0x00007fd6443cb000,0x00007fd6444cc000], sp=0x00007fd6444c6320, free space=1004k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x12fef24] PhaseIdealLoop::build_loop_early(VectorSet&, Node_List&, Node_Stack&)+0x6d4
V [libjvm.so+0x130841a] PhaseIdealLoop::build_and_optimize(LoopOptsMode)+0x49a
V [libjvm.so+0xa2b300] PhaseIdealLoop::verify(PhaseIterGVN&)+0x2f0
V [libjvm.so+0xa261a8] Compile::Optimize()+0x6d8
V [libjvm.so+0xa28b48] Compile::Compile(ciEnv*, ciMethod*, int, bool, bool, bool, bool, bool, DirectiveSet*)+0x1618
V [libjvm.so+0x849aa6] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x646
V [libjvm.so+0xa397a9] CompileBroker::invoke_compiler_on_method(CompileTask*)+0xfb9
V [libjvm.so+0xa3a518] CompileBroker::compiler_thread_loop()+0x5a8
V [libjvm.so+0x18b8251] JavaThread::thread_main_inner()+0x271
V [libjvm.so+0x18bff70] Thread::call_run()+0x100
V [libjvm.so+0x158c7c4] thread_native_entry(Thread*)+0x104