RFR (XS) JDK-8015272: Make @Contended within the same group to use the same oop map

[David Holmes]

On 11/11/2014 9:38 PM, Aleksey Shipilev wrote:
> Thanks for review, Coleen!
>
> On 11.11.2014 03:37, Coleen Phillimore wrote:
>> Hi, I think this code looks correct.  Was there a test in the test
>> system that exercises this code?  I think it would be hard to test with
>> a dedicated test but was there one already in the test sets?
>
> Yes, there are @Contended tests in vmtestbase that exercise the
> @Contended placed over different fields. I added the targeted test that
> also does walk through new code. There is nothing to check there, except
> for the native assert in the new code.
>
>> Secondly, could you use the word adjacent in the comments, reuse oopmap
>> for adjacent oops in the class or something like that?  That would have
>> saved me some jotting down on notebook.
>
> Sure, see the update. In previous change, I blindly copied the block
> already available for non- at Contended oops. I remember the oop maps code
> was tripping me over, this is why we have an explanation all the way on
> the top how oop maps are supposed to work.
>
>> I'll sponsor it if you get another reviewer.

I'll add my Review. Changes seem okay.

Looks like the style-Police didn't pay enough attention to this section 
of code though as a lot of:

   if( XXX )

have crept in instead of:

   if (XXX)

;-)

Cheers,
David

> Here's the updated webrev:
>   http://cr.openjdk.java.net/~shade/8015272/webrev.02/
>
> I have only tested in builds on Linux x86_64/fastdebug, and passes
> runtime/contended jtregs. There were no changes in product code since
> last webrev, only in comments.
>
> Thanks,
> -Aleksey.
>