C1 clone intrinsic needs memory barriers

==== Symptoms ====
The JTReg test wrapper 'applications/jcstress/copy.java' failed.
The failure has been caused by the inner JCStress test 'org.openjdk.jcstress.tests.copy.clone.arrays.small.plain.FloatTest'
The failure message:

                  RESULT SAMPLES FREQ EXPECT DESCRIPTION
            true, 1, 0.0 2 <0.01% Acceptable Seeing array, but not its contents.
        true, 1, 1.4E-45 1 <0.01% Forbidden No default case provided, assume Forbidden <<<< ERROR
  true, 1, 2.3509528E-38 3,306,688,528 100.00% Acceptable Seeing the complete update.

==== Root cause ====
Missing memory barrier in C1

==== Original Description ====
Hard to decipher:

Observed forbidden state: true, 1, -17730 (No default case provided, assume Forbidden)

at org.openjdk.jcstress.infra.grading.ExceptionReportPrinter.work(ExceptionReportPrinter.java:63)
at org.openjdk.jcstress.JCStress.parseResults(JCStress.java:140)
at org.openjdk.jcstress.JCStress.run(JCStress.java:107)
at org.openjdk.jcstress.Main.main(Main.java:60)
]cout/cerr
java.lang.Error: jctress test finished with nonzero exitcode 1
at applications.jcstress.JcstressRunner.main(JcstressRunner.java:89)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:333)
at java.base/java.lang.Thread.run(Thread.java:1575)