The following test failed in the JDK16 CI:

compiler/loopopts/TestDivZeroWithSplitIf.java

Here's a snippet from the log file:

#section:main
----------messages:(4/476)----------
command: main -Xcomp -XX:-TieredCompilation -XX:CompileOnly=compiler/loopopts/TestDivZeroWithSplitIf::test -XX:+StressGCM -XX:StressSeed=873732072 compiler.loopopts.TestDivZeroWithSplitIf
reason: User specified action: run main/othervm -Xcomp -XX:-TieredCompilation -XX:CompileOnly=compiler/loopopts/TestDivZeroWithSplitIf::test -XX:+StressGCM -XX:StressSeed=873732072 compiler.loopopts.TestDivZeroWithSplitIf 
Mode: othervm [/othervm specified]
elapsed time (seconds): 0.005
----------configuration:(0/0)----------
----------System.out:(0/0)----------
----------System.err:(4/258)----------
Error: VM option 'StressGCM' is diagnostic and must be enabled via -XX:+UnlockDiagnosticVMOptions.
Error: The unlock option must precede 'StressGCM'.
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
----------rerun:(38/5923)*----------