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Re: Lisp_Marker size on 32bit systems

From: Stefan Monnier
Subject: Re: Lisp_Marker size on 32bit systems
Date: Thu, 06 Sep 2018 08:17:40 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)

>> used to be 24 (bytes) when we used Lisp_Misc, but it is now 32
>> (bytes) instead!
> I'll take a look at it.

Thanks.  AFAICT the only solution is to use the GCALIGNED_UNION trick in
each and every "real Lisp_Object struct" rather than once and forall in

Maybe we should use a LISP_STRUCT macro like

    #define LISP_STRUCT(name, fields) \
      struct name { union { struct { fields } s; GCALIGNED_UNION; } u; }

> I was hoping those 8 bytes wouldn't make enough
> difference to worry about, but evidently not....

It's really the 4 extra padding bytes incurred by all vectorlikes that
annoy me.  The resulting extra 8 bytes in markers is just a symptom ;-)


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