RFR(S) Contended Locking cleanup bucket (8062851)

[David Holmes]

Hi Dan,

Reviewed.

I find the name OM_OFFSET_NO_MONITOR_VALUE somewhat awkward but have no 
better suggestion. In fact I have to ask what _is_ the object monitor 
tagging mechanism? I can't see it defined in the objectMonitor.* files. ??

Thanks,
David

On 5/11/2014 2:34 PM, Daniel D. Daugherty wrote:
> 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