RFR: 8305896: Alternative full GC forwarding [v29]

[Roman Kennke]

On Thu, 4 May 2023 12:53:23 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add usual header include guards
>
> src/hotspot/share/gc/shared/slidingForwarding.inline.hpp line 60:
> 
>> 58:   } else if (_bases_table[base_idx] == UNUSED_BASE) {
>> 59:     // Primary is free
>> 60:     _bases_table[base_idx] = to_region_base;
> 
> Since the else branch is probably much more common, would it make sense to swap the conditions? Same below.

I just swapped that around to what it is now: I think the UNUSED_BASE would be taken exactly once per region, then every other call would find a 'good' target. Which means the if-branch would be much more common and else only taken rarely.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13582#discussion_r1185251911