GNU bug report logs - #18410
Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.

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Package: emacs;

Reported by: Paul Eggert <eggert <at> cs.ucla.edu>

Date: Fri, 5 Sep 2014 06:10:02 UTC

Severity: wishlist

Tags: patch

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

Full log

Message #20 received at 18410 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Dmitry Antipov <dmantipov <at> yandex.ru>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, 18410 <at> debbugs.gnu.org
Subject: Re: bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack
 allocation.
Date: Fri, 05 Sep 2014 11:44:25 -0400

> USE_SAFE_ALLOCA;                                                    |-
> ptrdiff_t count = SPECPDL_INDEX ();                    |-           |
> ...                                                    | inner bind | outer bind
> Lisp_Object result = unbind_to (count, Fsome_func ()); |-           |
> SAFE_FREE ();                                                       |-
> return result;
>
> looks suboptimal because it calls unbind_to twice.

Only if the object is "too large" and requires heap allocation.

BTW, AFAIK

   Lisp_Object result = unbind_to (count, Fsome_func ());

can always be written

   Lisp_Object result = Fsome_func ();
   unbind_to (count, Qnil);

which I find more readable (if it were me, unbind_to would take
a single arg and return void).


        Stefan
This bug report was last modified 10 years and 258 days ago.

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