RFR(S) Contended Locking cleanup bucket (8062851)

[Daniel D. Daugherty]

Greetings,

I have a Contended Locking cleanup bucket fix ready for review.

This fix was spun off from the Contended Locking fast enter bucket
which was sent out for review late last week. This fix cleans up
the computation of ObjectMonitor field pointers and gets rid of
the use of literal '-2' in appropriate places. For example:

-         ld_ptr(Rmark, ObjectMonitor::owner_offset_in_bytes() - 2, 
Rscratch);
+         ld_ptr(Rmark, OM_OFFSET_NO_MONITOR_VALUE(owner), Rscratch);

The OM_OFFSET_NO_MONITOR_VALUE macro computes the offset to the
specified field and subtracts markOopDesc:monitor_value (2).
There's a nice comment in src/share/vm/runtime/objectMonitor.hpp.

Thanks to David Holmes for his comments on JDK-8061553 that
motivated this (long overdue) cleanup.

This work is being tracked by the following bug ID:

     JDK-8062851 cleanup ObjectMonitor offset adjustments
     https://bugs.openjdk.java.net/browse/JDK-8062851

Here is the webrev URL:

http://cr.openjdk.java.net/~dcubed/8062851-webrev/0-jdk9-hs-rt/

Here is the JEP link:

     https://bugs.openjdk.java.net/browse/JDK-8046133

Testing:

- JPRT test jobs (since this is only syntax and comment cleanup)

Thanks, in advance, for any comments, questions or suggestions.

Dan