[7u4] Request for approval for 7030453: JSR 292 ClassValue.get method is too slow

[John Rose]

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7030453

The change will be in JDK 8 with the next integration from HSX, where it presently resides:

http://hg.openjdk.java.net/hsx/hotspot-main/jdk/rev/92d2cba30f08

This change set has also been active in the mlvm repository from 8/2011 to (final form) 12/2011:
 http://hg.openjdk.java.net/mlvm/mlvm/jdk/file/ea20028ecbf4/cval-tune-7030453.patch

Although this is a low-priority bug and primarily a performance issue, replacing the table-based implementation with a direct-linked implementation removed at least one race condition.  Therefore, I recommend that we back port this, for correctness.

Technical discussion is here:
  http://mail.openjdk.java.net/pipermail/mlvm-dev/2011-September/003930.html

-- John