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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/61034] Optimizing takes too many passes
Date: Wed, 07 May 2014 11:08:00 -0000	[thread overview]
Message-ID: <bug-61034-4-HP49vMw8Uh@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-61034-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61034

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #7)
> (In reply to rguenther@suse.de from comment #6)
> > that's a conditional assignment AFAICS
> 
> Ah, you are right of course. It shouldn't be conditional, but it will take a
> VRP pass to notice that. If I schedule another FRE right after VRP1, things
> optimize nicely, and after some cleanup by DOM+DSE, DCE2 can remove all
> malloc+free. However, if I don't add this extra FRE pass, we somehow don't
> manage. Note that in the PRE dump, with just your patch (no extra pass), I
> see:
> 
>   pretmp_92 = 1;
>   _235 = pretmp_92;
>   if (_235 == 0)
> 
> and these conditions seem to be what prevents us from finishing the job.

Yeah.  Looks somewhat tricky, but I'll play with it.  Meanwhile testing
a proper patch for the first issue.


  parent reply	other threads:[~2014-05-07 11:08 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-02 10:52 [Bug tree-optimization/61034] New: " glisse at gcc dot gnu.org
2014-05-05 10:25 ` [Bug tree-optimization/61034] " rguenth at gcc dot gnu.org
2014-05-05 10:33 ` rguenth at gcc dot gnu.org
2014-05-05 10:48 ` rguenth at gcc dot gnu.org
2014-05-05 11:56 ` glisse at gcc dot gnu.org
2014-05-05 12:19 ` rguenther at suse dot de
2014-05-05 13:41 ` glisse at gcc dot gnu.org
2014-05-07 11:08 ` rguenth at gcc dot gnu.org [this message]
2014-05-07 11:50 ` rguenth at gcc dot gnu.org
2014-05-07 14:19 ` rguenth at gcc dot gnu.org
2014-05-07 15:14 ` glisse at gcc dot gnu.org
2014-05-08 10:00 ` rguenther at suse dot de

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