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Re: [PATCH] Re: Bignum performance


From: Gerd Möllmann
Subject: Re: [PATCH] Re: Bignum performance
Date: Wed, 16 Aug 2023 10:05:36 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0

On 16.08.23 08:42, Po Lu wrote:
Gerd Möllmann <gerd.moellmann@gmail.com> writes:

I don't know about SBCL, but as for Emacs, refer to the definition of
VALBITS in lisp.h (maybe also the right files among m/*.h and s/*.h, but
I have no idea where they've disappeared to.)

The SBCL I have here, a Homebrew installation, uses the scheme where

....0   -> fixnum
....1   -> other objects (discriminated by additional tag bits)

I had the same for Emacs in the branch gerd_int in the 2000s, if
memory serves me.

In today's Emacs, 0 is Lisp_Symbol; this facilitates representing Qnil
as C NULL.

Yes, and I don't see a need to change anything in this regard in Emacs. IMHO, the fixnum range is more than sufficient nowadays, in general.



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