The tests I've seen fail are:

TEST: java/util/concurrent/BlockingQueue/CancelledProducerConsumerLoops.java
TEST: java/util/concurrent/BlockingQueue/MultipleProducersSingleConsumerLoops.java
TEST: java/util/concurrent/BlockingQueue/ProducerConsumerLoops.java
TEST: java/util/concurrent/ConcurrentQueues/ConcurrentQueueLoops.java
TEST: java/util/concurrent/Exchanger/ExchangeLoops.java
TEST: java/util/concurrent/ExecutorCompletionService/ExecutorCompletionServiceLoops.java
TEST: java/util/concurrent/FutureTask/CancelledFutureLoops.java
TEST: java/util/concurrent/locks/ReentrantLock/LockOncePerThreadLoops.java
TEST: java/util/concurrent/locks/ReentrantLock/SimpleReentrantLockLoops.java
TEST: java/util/concurrent/locks/ReentrantLock/TimeoutLockLoops.java
TEST: java/util/concurrent/locks/ReentrantReadWriteLock/MapLoops.java

This bug is easily reproducible with:

jtreg -verbose:all -noreport -jdk:$PWD/build/macosx-x86_64-normal-server-release/images/jdk -vmoptions:"-XX:+UnlockExperimentalVMOptions -XX:+EnableJVMCI -XX:+UseJVMCICompiler" jdk/test/java/util/concurrent/BlockingQueue/CancelledProducerConsumerLoops.java

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (c1_LIRAssembler_x86.cpp:2032), pid=21760, tid=28419
# Error: ShouldNotReachHere()
#
# JRE version: OpenJDK Runtime Environment (10.0) (build 10-internal+0-adhoc.cthalinger.hs)
# Java VM: OpenJDK 64-Bit Server VM (10-internal+0-adhoc.cthalinger.hs, mixed mode, tiered, jvmci, jvmci compiler, compressed oops, g1 gc, bsd-amd64)
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /Users/cthalinger/jdk10/hs/JTwork/scratch/hs_err_pid21760.log
#
# Compiler replay data is saved as:
# /Users/cthalinger/jdk10/hs/JTwork/scratch/replay_pid21760.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

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

Current thread (0x00007fcaf58e5800): JavaThread "C1 CompilerThread3" daemon [_thread_in_native, id=28419, stack(0x000070000ba8a000,0x000070000bb8a000)]


Current CompileTask:
C1: 128 274 3 LoopHelpers::compute2 (28 bytes)

Stack: [0x000070000ba8a000,0x000070000bb8a000], sp=0x000070000bb88e90, free space=1019k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.dylib+0x6e665a] VMError::report_and_die(int, char const*, char const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x4ca
V [libjvm.dylib+0x6e6cce] VMError::report_and_die(Thread*, char const*, int, char const*, char const*, __va_list_tag*)+0x3c
V [libjvm.dylib+0x26e1e6] report_vm_error(char const*, int, char const*, char const*, ...)+0xa2
V [libjvm.dylib+0x17cec4] LIR_Assembler::arith_op(LIR_Code, LIR_OprDesc*, LIR_OprDesc*, LIR_OprDesc*, CodeEmitInfo*, bool)+0x1134
V [libjvm.dylib+0x172f7f] LIR_Assembler::emit_op2(LIR_Op2*)+0x61
V [libjvm.dylib+0x171ff3] LIR_Assembler::emit_lir_list(LIR_List*)+0x4b
V [libjvm.dylib+0x17204f] LIR_Assembler::emit_code(BlockList*)+0x2b
V [libjvm.dylib+0x153163] Compilation::emit_code_body()+0x127
V [libjvm.dylib+0x153498] Compilation::compile_java_method()+0x10a
V [libjvm.dylib+0x153647] Compilation::compile_method()+0x71
V [libjvm.dylib+0x15383e] Compilation::Compilation(AbstractCompiler*, ciEnv*, ciMethod*, int, BufferBlob*, DirectiveSet*)+0x184
V [libjvm.dylib+0x154c31] Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x61
V [libjvm.dylib+0x2425fb] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x539
V [libjvm.dylib+0x241ebf] CompileBroker::compiler_thread_loop()+0x1b3
V [libjvm.dylib+0x6a6fe0] JavaThread::thread_main_inner()+0x82
V [libjvm.dylib+0x6a6e53] JavaThread::run()+0x18b
V [libjvm.dylib+0x5ae8ac] thread_native_entry(Thread*)+0x135
C [libsystem_pthread.dylib+0x393b] _pthread_body+0xb4
C [libsystem_pthread.dylib+0x3887] _pthread_body+0x0
C [libsystem_pthread.dylib+0x308d] thread_start+0xd
C 0x0000000000000000