RFR(S): 7133038: G1: Some small profile based optimizations

[John Cuthbertson]

Hi There,

Can I have a couple of volunteers review the changes for this CR? The 
webrev can be found at: http://cr.openjdk.java.net/~johnc/7133038/webrev.0/

Summary:
While going through hardware profiles of various G1 workloads we were 
seeing some high data cache miss rates, and a high number of branches 
and branch mispredicts in some routines. These routines help to reduce 
those by adding prefetching and some minor code refactoring.

Testing: GC test suite; jprt; specjbb2005 (to verify the profiling).

Thanks,

JohnC