RFR (M): 8071278: Fix the closure mess in G1RemSet::refine_card()

[Kim Barrett]

> On Feb 23, 2017, at 6:23 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>   one line:
> 
> "188 lines changed: 23 ins; 143 del; 22 mod; 3097 unchg"
> 
> This is a rip-out and manual collapsing of needlessly complex code in
> the update rs algorithm.
> 
> There are more improvements obvious now in that area (JDK-8071280, JDK-
> 8162928, JDK-8175554 at least), so I kept this one to the minimum.
> 
> The change makes the code a bit faster too due to avoiding repeated
> null-checks, region-crossing checks etc. etc.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8071278
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8071278/webrev/
> Testing:
> jprt, tier2+3 testing, some benchmarks
> 
> Thanks,
>   Thomas

Looks good.