RFR: Add generations to freeset [v21]

[Kelvin Nilsen]

On Mon, 1 May 2023 16:43:49 GMT, Y. Srinivas Ramakrishna <ysr at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Respond to reviewer feedback
>
> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp line 272:
> 
>> 270:   // request.  Regions become sparsely distributed following a Full GC, which tends to slide all regions to the front of the
>> 271:   // heap rather than allowing survivor regions to remain at the high end of the heap where we intend for them to congregate.
>> 272:   // In the future, we may modify Full GC so that it slides old objects to the end of the heap and young objects to the start
> 
> Mark with a `TODO:` ?

Thanks.  Done.

> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.hpp line 92:
> 
>> 90:   // In other words:
>> 91:   //   if the requested which_set is empty:
>> 92:   //     left_most() and left_most_empty() return _max, right_most() and right_most_empty() return 0
> 
> I think you an elide the "_" underscore in left_most (leftmost is an English word). It also makes `leftmost_empty` easier to read.
> 
> Would be great if you can make that global substitution in your comments etc. as well before checking in. (Or make it all have the underscore consistently in comments too if you prefer the variant with the underscore.)

Thanks.  Done.

> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.hpp line 124:
> 
>> 122: 
>> 123:   // Assure leftmost, rightmost, leftmost_empty, and rightmost_empty bounds are valid for all free sets.
>> 124:   // valid bounds honor all of the following (where max is the number of heap regions):
> 
> Valid (upper-case V).

Thanks.  Done.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/250#discussion_r1181926504
PR Review Comment: https://git.openjdk.org/shenandoah/pull/250#discussion_r1181927354
PR Review Comment: https://git.openjdk.org/shenandoah/pull/250#discussion_r1181927451