RFR: 8339960: GenShen: Fix inconsistencies in generational Shenandoah behavior

[Kelvin Nilsen]

On Wed, 11 Sep 2024 16:33:08 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> This fixes some bugs found in recent code review and playback of an assertion failure.
>
> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp line 1428:
> 
>> 1426:                 old_collector_regions, old_collector_used);
>> 1427: 
>> 1428:   idx_t rightmost_idx = (mutator_leftmost == max_regions)? -1: (idx_t) mutator_rightmost;
> 
> Does this also affect upstream? Should we have a non-genshen patch too?

We should do this upstream as well.  (or it will go upstream when we merge, but that might take a while). I wanted to test and integrate "quickly" into our internal test distribution.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/497#discussion_r1755147308