Re: m4_defn overhead

[Ralf Wildenhues]

Hello Eric,

* Eric Blake wrote on Thu, Oct 11, 2007 at 01:04:51AM CEST:
> 2007-10-10  Eric Blake  <address@hidden>
> 
>       Avoid some overhead from m4_defn and m4_popdef.
>       * lib/m4sugar/m4sugar.m4 (m4_defn, m4_popdef, m4_undefine): Only
>       pass on first argument, since we are documented that way.
>       (m4_for, m4_append_uniq, m4_text_wrap): Optimize out defined-ness
>       check where it is safe to do so.
>       (m4_append): Likewise, and quote the separator.
>       (m4_text_box): Likewise, and avoid regex, also be robust to
>       expansion and quadrigraphs.

This patch causes a regression with CVS Libtool: its configure script is
unusably botched with this.  More specifically, when I revert the hunk
below, things look better, but I haven't analysed this further.  I can't
even tell whether it's Libtool to blame (but even if it is, we may want
to be a bit careful anyway).  If it's not, then some Autoconf testsuite
addition would seem to be in order.

Cheers,
Ralf

> diff --git a/lib/m4sugar/m4sugar.m4 b/lib/m4sugar/m4sugar.m4
> index 952794a..85f2c72 100644
> --- a/lib/m4sugar/m4sugar.m4
> +++ b/lib/m4sugar/m4sugar.m4
[...]
> @@ -1680,9 +1681,11 @@ m4_defun([m4_join],
>  #    => act1
>  #    =>
>  #    => active
> +#
> +# Use m4_builtin to avoid overhead of m4_defn.
>  m4_define([m4_append],
>  [m4_define([$1],
> -        m4_ifdef([$1], [m4_defn([$1])$3])[$2])])
> +        m4_ifdef([$1], [m4_builtin([defn], [$1])[$3]])[$2])])
>  
>  
>  # m4_append_uniq(MACRO-NAME, STRING, [SEPARATOR])