Re: Matching regex case-sensitively in C strings?

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Wed, 9 Nov 2022 11:33:09 +0100
> Cc: Yuan Fu <casouri@gmail.com>, emacs-devel@gnu.org
> 
> 8 nov. 2022 kl. 20.37 skrev Eli Zaretskii <eliz@gnu.org>:
> 
> >> fast_c_string_match_ignore_case (Lisp_Object regexp,
> >>                             const char *string, ptrdiff_t len)
> >> {
> >> +  return fast_c_string_match (regexp, string, len, true);
> >> +}
> > 
> > I'm bothered that this function, which is supposed to be fast, will
> > now be slower due to an extra function call.
> 
> You are right to worry about it, but there is actually no need for
> concern here: it's a tail call (and the extra argument is last) so
> it should compile to an unconditional jump (and setting a register).

That's not what I see here, even with -O2.