Re: [PATCH] Re: Bignum performance

[Gerd Möllmann]

> 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.