I'm seeing a number tests hanging or misbehaving on solaris-sparcv9 since jdk7-b27 was promoted. jdk7-b27 has HotSpot 13.0-b01. Problems go away if I run with -Xint or exclude specific methods from compilation. I pulled in HotSpot 12.0-b03 from jdk7-b26 and don't observe any problems so this looks like a regression.

Here's an example of a regression test in the JDK repository where compareAndSet seems to be broken:
  test/java/nio/channels/SelectionKey/AtomicAttachTest.java

Works okay when this method is excluded:
exclude java/util/concurrent/atomic/AtomicReferenceFieldUpdater getAndSet

The following is another small test which is hacked from a much larger test that hangs with jdk7-b27. In this case, the test works when java.util.concurrent.locks.AbstractQueuedSynchronizer.enq is excluded from compilation.

import java.util.concurrent.*;

public class Test {
    public static void main(String[] args) throws Exception {
        Executor executor = Executors.newFixedThreadPool(1,
            new ThreadFactory() {
                public Thread newThread(Runnable r) {
                    Thread t = new Thread(r);
                    t.setDaemon(true);
                    return t;
                }
            });

        int i = 0;
        while (i<10000) {
            final CountDownLatch latch =  new CountDownLatch(1);
            executor.execute(new Runnable() {
                public void run() {
                    latch.countDown();
                }
            });
            latch.await();
            i++;
        }
    }
}