[master] RFR: Smaller class pointers [v2]

[Thomas Stuefe]

On Tue, 7 Dec 2021 07:35:23 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove include add in chunklevel.hpp
>
> src/hotspot/share/cds/archiveBuilder.cpp line 222:
> 
>> 220:     }
>> 221:     // See RunTimeClassInfo::get_for()
>> 222:     _estimated_metaspaceobj_bytes += align_up(BytesPerWord, KlassAlignmentInBytes);
> 
> Small nit here: The original code was intended to reserve space for an extra pointer that's placed immediately below each Klass. I think we should do this so that the intention is clear.
> 
> 
> // Reserve a slot to store a RunTimeClassInfo pointer immediately below each Klass.
> // See RunTimeClassInfo::get_for()
> _estimated_metaspaceobj_bytes += BytesPerWord;
> // Extra padding for make sure each Klass is aligned.
> _estimated_metaspaceobj_bytes += KlassAlignmentInBytes;

Okay, I fixed it and modified the comments in both gather_klass_and_symbol and make_shallow_copy to be clearer to non-CDS people. Could you take a look at them?

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PR: https://git.openjdk.java.net/lilliput/pull/13