RFR(S): Ensure collection set and cset map are consistent, and a few cleanup

[Aleksey Shipilev]

On 05/31/2017 08:25 PM, Zhengyu Gu wrote:
>>  *) Is removal of this branch meaningful? It was supposed to avoid some stores:
>>
>>  228         if (!r->is_root()) {
>>  229           r->set_root(true);
>>  230         }
> 
> Just a bit awkward. Do those stores matter? It is at a safepoint, and you have
> region in cache anyway.

Yes it does. Trading write for branch is a profitable microoptimization,
especially if you are looking into doing Threshold*NumRegions of writes ;)

-Aleksey