RFR (S): 8242036: G1 HeapRegionRemSet::_n_coarse_entries could be a bool

[Kim Barrett]

> On Jul 24, 2020, at 6:59 AM, Albert Yang <albert.m.yang at oracle.com> wrote:
> 
> I don't think calling `at_put` unconditionally is clearer, since `_coarse_map.at_put` needs be after `_coarse_map.reinitialize`, which only happens when `_has_coarse_entries` is false.
> 
> Maybe I misunderstood what you meant.

I meant drop the conditional on line 267 (see below):

> On 2020-07-24 10:23, Kim Barrett wrote:
>> src/hotspot/share/gc/g1/heapRegionRemSet.cpp
>> 267     if (!_coarse_map.at(max_hrm_index)) {
>> 268       _coarse_map.at_put(max_hrm_index, true);
>> 269     }
>> 
>> The old code conditionalized on !_course_map.at() to avoid
>> incrementing _n_coarse_entries if the entry was already set.  That's
>> no longer needed.  It seems like it might be clearer to just do the
>> at_put unconditionally.  If so, also change the comment on line 264 to
>> say something like "Ensure the corresponding coarse bit is set."