The following test failed in the JDK21 CI:

java/util/concurrent/tck/JSR166TestCase.java

Here's a snippet from the log file:

#section:junit
----------messages:(7/375)----------
command: junit -Djava.security.manager=allow JSR166TestCase
reason: User specified action: run junit/othervm/timeout=1000 -Djava.security.manager=allow JSR166TestCase
started: Thu May 18 19:35:28 UTC 2023
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules java.management
finished: Thu May 18 19:38:09 UTC 2023
elapsed time (seconds): 161.27
----------configuration:(3/43)----------
Boot Layer
  add modules: java.management

----------System.out:(30/2324)----------
dist dump
---------------------------------------------
   0 748 If === 886 980 [[ 559 ]] P=0.008410, C=-1.000000 !orig=[2622] !jvms: AbstractPipeline::copyInto @ bci:38 (line 510) ForEachOps$ForEachTask::compute @ bci:103 (line 291)
   1 559 IfTrue === 748 [[ 361 ]] #1 !orig=[2624] !jvms: AbstractPipeline::copyInto @ bci:38 (line 510) ForEachOps$ForEachTask::compute @ bci:103 (line 291)
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/mach5/mesos/work_dir/slaves/741e9afd-8c02-45c3-b2e2-9db1450d0832-S108520/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/c494988c-691e-438f-8e14-974f1464b984/runs/dd4c8f6a-ee38-4f06-9174-5a88e6525123/workspace/open/src/hotspot/share/opto/compile.cpp:4003), pid=406338, tid=406353
# assert(false) failed: malformed control flow
#
# JRE version: Java(TM) SE Runtime Environment (21.0+24) (fastdebug build 21-ea+24-LTS-2001)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-ea+24-LTS-2001, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
# Problematic frame:
# V [libjvm.so+0x9092b8] Compile::final_graph_reshaping()+0x11a8
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to /opt/mach5/mesos/work_dir/slaves/741e9afd-8c02-45c3-b2e2-9db1450d0832-S108190/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/3abccbf0-b279-4e04-883e-dcf3bac90689/runs/ddf03d8d-dfe3-4a3e-91bb-bcdf6b5267b9/testoutput/test-support/jtreg_open_test_jdk_tier1/scratch/0_1/core.406338)
#
# An error report file with more information is saved as:
# /opt/mach5/mesos/work_dir/slaves/741e9afd-8c02-45c3-b2e2-9db1450d0832-S108190/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/3abccbf0-b279-4e04-883e-dcf3bac90689/runs/ddf03d8d-dfe3-4a3e-91bb-bcdf6b5267b9/testoutput/test-support/jtreg_open_test_jdk_tier1/scratch/0_1/hs_err_pid406338.log
[thread 407902 also had an error][thread 407824 also had an error][thread 407219 also had an error]


[thread 407823 also had an error]
[thread 407446 also had an error]
[thread 406359 also had an error]
[thread 409107 also had an error]
[thread 407411 also had an error]

------ Timeout during error reporting after 120 s. ------
# [ timer expired, abort... ]
----------System.err:(1085/85321)----------


Here's the crashing thread's stack:

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

Current thread (0x0000ffffb43250f0): JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=406353, stack(0x0000ffff9c5da000,0x0000ffff9c7da000) (2048K)]


Current CompileTask:
C2: 30775 5948 4 java.util.stream.ForEachOps$ForEachTask::compute (183 bytes)

Stack: [0x0000ffff9c5da000,0x0000ffff9c7da000], sp=0x0000ffff9c7d4a50, free space=2026k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x9092b8] Compile::final_graph_reshaping()+0x11a8 (compile.cpp:4003)
V [libjvm.so+0x90a804] Compile::Optimize()+0x14f0 (compile.cpp:2450)
V [libjvm.so+0x90bddc] Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x1488 (compile.cpp:839)
V [libjvm.so+0x762c48] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x328 (c2compiler.cpp:118)
V [libjvm.so+0x917f44] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x974 (compileBroker.cpp:2265)
V [libjvm.so+0x918a64] CompileBroker::compiler_thread_loop()+0x590 (compileBroker.cpp:1944)
V [libjvm.so+0xdacf7c] JavaThread::thread_main_inner()+0xec (javaThread.cpp:719)
V [libjvm.so+0x15f9f94] Thread::call_run()+0xb0 (thread.cpp:217)
V [libjvm.so+0x1353fd0] thread_native_entry(Thread*)+0x130 (os_linux.cpp:775)
C [libpthread.so.0+0x7908] start_thread+0x188