Re: Shrinking the C core

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: Emanuel Berg <incal@dataswamp.org>, emacs-devel@gnu.org
> Date: Sun, 20 Aug 2023 15:36:34 +0000
> 
> I am asking genuinely because `car' (1) has dedicated opt code and thus
> should be one of the best-optimized function calls on Elisp side; (2)
> Fcar is nothing but
> 
> /* Take the car or cdr of something whose type is not known.  */
> INLINE Lisp_Object
> CAR (Lisp_Object c)
> {
>   if (CONSP (c))
>     return XCAR (c); // <- XCONS (c)->u.s.car
>   if (!NILP (c))
>     wrong_type_argument (Qlistp, c);
>   return Qnil;
> }

'car' does have a dedicated bytecode op-code, but that op-code simply
calls XCAR, exactly like Fcar and CAR above do:

        CASE (Bcar):
          if (CONSP (TOP))
            TOP = XCAR (TOP);
          else if (!NILP (TOP))
            wrong_type_argument (Qlistp, TOP);
          NEXT;