java -XX:CompileCommand=quiet -XX:CompileCommand=compileonly,Test::mainTest -XX:-TieredCompilation -Xbatch -XX:+StressIGVN -XX:RepeatCompilation=100 Test.java

Or with -XX:StressSeed=821213477 instead of RepeatCompilation

Error mixing types: vectory<I,8> and int:0

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/workspace/open/src/hotspot/share/opto/type.cpp:1331), pid=715923, tid=715942
# Error: ShouldNotReachHere()
#
# JRE version: Java(TM) SE Runtime Environment (26.0+21) (fastdebug build 26-ea+21-2147)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 26-ea+21-2147, mixed mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x1b977d9] Type::typerr(Type const*) const+0x79

Current CompileTask:
C2:16564 4 !b Test::mainTest (750 bytes)

Stack: [0x000000ec90300000,0x000000ec90400000], sp=0x000000ec903fb390, free space=1004k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [jvm.dll+0x108afae] Type::typerr+0x6e (type.cpp:1331)
V [jvm.dll+0x108f272] TypeVect::xmeet+0x1b2 (type.cpp:2469)
V [jvm.dll+0x1089b7f] Type::meet_helper+0x2af (type.cpp:1027)
V [jvm.dll+0x273a3a] AddNode::add_of_identity+0x8a (addnode.cpp:240)
V [jvm.dll+0x2732da] AddNode::Value+0xda (addnode.cpp:228)
V [jvm.dll+0xe4f836] PhaseIterGVN::transform_old+0x2a6 (phaseX.cpp:2151)
V [jvm.dll+0xe4b13d] PhaseIterGVN::optimize+0x2ad (phaseX.cpp:1055)
V [jvm.dll+0x5c2b2f] Compile::Optimize+0xbaf (compile.cpp:2511)
V [jvm.dll+0x5bf819] Compile::Compile+0x10f9 (compile.cpp:861)
V [jvm.dll+0x4c3db9] C2Compiler::compile_method+0x179 (c2compiler.cpp:150)
V [jvm.dll+0x5ddad3] CompileBroker::invoke_compiler_on_method+0x843 (compileBroker.cpp:2355)
V [jvm.dll+0x5daebc] CompileBroker::compiler_thread_loop+0x27c (compileBroker.cpp:1990)
V [jvm.dll+0x927171] JavaThread::thread_main_inner+0x251 (javaThread.cpp:772)
V [jvm.dll+0x105934e] Thread::call_run+0x1be (thread.cpp:248)
V [jvm.dll+0xe001e4] thread_native_entry+0xc4 (os_windows.cpp:555)
C [ucrtbase.dll+0x14ea0] (no source info available)
C [KERNEL32.DLL+0x2dbe7] (no source info available)
C [ntdll.dll+0x85a6c] (no source info available)