Running into the following assert while testing some changes

# Internal Error (/home/albatem/ws/jdk/open/src/hotspot/share/opto/loopnode.cpp:5523), pid=2082704, tid=2082731
# assert(!in->is_CFG()) failed: CFG Node with no controlling input?

Current CompileTask:
C2: 1878 2115 4 java.lang.VirtualThread$VThreadContinuation$1::run (12 bytes)

Stack: [0x00007fde6d5f1000,0x00007fde6d6f1000], sp=0x00007fde6d6ebd30, free space=1003k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x12970c6] PhaseIdealLoop::build_loop_early(VectorSet&, Node_List&, Node_Stack&)+0x766 (loopnode.cpp:5523)
V [libjvm.so+0x12a2d10] PhaseIdealLoop::build_and_optimize()+0x5b0 (loopnode.cpp:4446)
V [libjvm.so+0x9f0209] PhaseIdealLoop::optimize(PhaseIterGVN&, LoopOptsMode)+0x3b9 (loopnode.hpp:1110)
V [libjvm.so+0x9eb1c0] Compile::Optimize()+0x820 (compile.cpp:2307)
V [libjvm.so+0x9eefd0] Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x1bb0 (compile.cpp:854)
V [libjvm.so+0x849feb] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x13b (c2compiler.cpp:119)
V [libjvm.so+0x9faf40] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x980 (compileBroker.cpp:2285)
V [libjvm.so+0x9fbd78] CompileBroker::compiler_thread_loop()+0x5f8 (compileBroker.cpp:1946)
V [libjvm.so+0xeb784c] JavaThread::thread_main_inner()+0xcc (javaThread.cpp:720)
V [libjvm.so+0x17a2fea] Thread::call_run()+0xba (thread.cpp:220)
V [libjvm.so+0x14a1bda] thread_native_entry(Thread*)+0x12a (os_linux.cpp:785)

The issue is duplicated by editing src/java.base/share/classes/java/lang/VirtualThread.java and remove @ChangesCurrentThread from the run(Runnable) method. This annotation is not needed on this method as it doesn't change the current thread.

With that change, run Skynet like this:

cd test/jdk/java/lang/Thread/virtual/stress
java -XX:NativeMemoryTracking=summary -XX:FlightRecorderOptions=preserve-repository=false -XX:StartFlightRecording=dumponexit=true,settings=profile Skynet.java 100

The assert goes away if the method is changed to have DontInline so this is something to do with the inlining of run(Runnable) into its caller.