We started hitting this a lot in Valhalla but I noticed that it also triggers in the mainline CI:

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/workspace/open/src/hotspot/share/opto/graphKit.cpp:348), pid=6599, tid=6615
# assert(ex_jvms->sp() == phi_map->_jvms->sp()) failed: matching stack sizes
#
# JRE version: Java(TM) SE Runtime Environment (18.0+13) (fastdebug build 18-ea+13-623)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 18-ea+13-623, compiled mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0xd43e36] GraphKit::combine_exception_states(SafePointNode*, SafePointNode*) [clone .part.0]+0xc6
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to /testoutput/test-support/jck_runtime_api_java_util/core.6599)
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
Current CompileTask:
C2: 134735 11496 b javasoft.sqe.tests.api.java.util.concurrent.atomic.AtomicIntegerFieldUpdater.GetAndUpdate::test (65 bytes)

Stack: [0x00007f3dd82fb000,0x00007f3dd83fc000], sp=0x00007f3dd83f6fc0, free space=1007k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xd43e36] GraphKit::combine_exception_states(SafePointNode*, SafePointNode*) [clone .part.0]+0xc6
V [libjvm.so+0xd4f22c] GraphKit::replace_call(CallNode*, Node*, bool)+0x63c
V [libjvm.so+0x825c0b] CallGenerator::do_late_inline_helper()+0xbbb
V [libjvm.so+0xa04b3d] Compile::inline_incrementally_one()+0x33d
V [libjvm.so+0xa05427] Compile::process_late_inline_calls_no_inline(PhaseIterGVN&)+0x117
V [libjvm.so+0xa06d70] Compile::Optimize()+0x1860
V [libjvm.so+0xa084b8] Compile::Compile(ciEnv*, ciMethod*, int, bool, bool, bool, bool, bool, DirectiveSet*)+0x1588
V [libjvm.so+0x81cd56] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x646
V [libjvm.so+0xa18711] CompileBroker::invoke_compiler_on_method(CompileTask*)+0xd31
V [libjvm.so+0xa19448] CompileBroker::compiler_thread_loop()+0x598
V [libjvm.so+0x1886a5c] JavaThread::thread_main_inner()+0x27c
V [libjvm.so+0x188d050] Thread::call_run()+0x100
V [libjvm.so+0x156b244] thread_native_entry(Thread*)+0x104