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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/99339] Poor codegen with simple varargs
Date: Wed, 03 Mar 2021 08:41:07 +0000	[thread overview]
Message-ID: <bug-99339-4-6SJ53MSz0o@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99339-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99339

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The stdarg pass already performs similar analysis, see e.g.
reachable_at_most_once function, because if those aren't used in loops and
escape, it computes not just whether the function uses some fp or gpr args, but
also how many (though, upper bound for that).
For the optimization discussed here, it would need to punt also on cases like:
va_start
if (cond)
  va_arg
va_arg
(well, could assign the first va_arg a particular register, but not to the
other one).

      parent reply	other threads:[~2021-03-03  8:41 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-02 11:49 [Bug c/99339] New: " redbeard0531 at gmail dot com
2021-03-02 12:44 ` [Bug middle-end/99339] " rguenth at gcc dot gnu.org
2021-03-02 12:46 ` rguenth at gcc dot gnu.org
2021-03-02 12:53 ` rguenth at gcc dot gnu.org
2021-03-02 13:11 ` jakub at gcc dot gnu.org
2021-03-02 13:28 ` redbeard0531 at gmail dot com
2021-03-02 15:30 ` redbeard0531 at gmail dot com
2021-03-03  7:28 ` rguenth at gcc dot gnu.org
2021-03-03  8:41 ` jakub at gcc dot gnu.org [this message]

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