RFR: Mixed evacuation [v2]

[earthling-amzn]

On Mon, 12 Apr 2021 19:47:37 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Chasing bug during prepare_for_old_collection
>>   
>>   One bug fix, a few cosmetic improvements, a change in loop structure to possibly avoid a gcc
>>   optimization error.
>
> src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeuristics.cpp line 475:
> 
>> 473: 
>> 474:   // This loop is written as while rather than for because of
>> 475:   // suspected gcc error in translating/optimizing for-loop
> 
> WTF, really? Do we have any indication of this?

We will remove this comment. We saw some pretty strange behavior while debugging, but it turned out to be a bug in `rr`.

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PR: https://git.openjdk.java.net/shenandoah/pull/29