RFR: 8324649: Shenandoah: refactor implementation of free set [v4]

[Y. Srinivas Ramakrishna]

On Wed, 31 Jan 2024 00:45:20 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp line 401:
>> 
>>> 399: 
>>> 400: HeapWord* ShenandoahFreeSet::allocate_single(ShenandoahAllocRequest& req, bool& in_new_region) {
>>> 401:   shenandoah_assert_heaplocked();
>> 
>> In addition, another precondition for this method appears to be that req.size() <= humongous size threshold. Perhaps that check should also be disposed of here. (Based on the documentation at the previous review comment above.)
>
> Added similar documentation here.  Thanks.

I meant something like:

assert(req.size() <= ShenandoahHeapRegion::humongous_threshold_words(), "Can't exceed humongous size");


Unless the precondition is that it shouldn't exceed a region's worth in size, in which case: `<= ShenandoahHeapRegion::region_size_words().`

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PR Review Comment: https://git.openjdk.org/jdk/pull/17561#discussion_r1476987025