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From: "bonzini at gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/30521] "if (i == n) ++i;" or "i += i == n;"?
Date: Sat, 22 Nov 2008 10:17:00 -0000 [thread overview]
Message-ID: <20081122101542.22202.qmail@sourceware.org> (raw)
In-Reply-To: <bug-30521-315@http.gcc.gnu.org/bugzilla/>
------- Comment #7 from bonzini at gnu dot org 2008-11-22 10:15 -------
Subject: Re: "if (i == n) ++i;" or "i += i == n;"?
> The form of the code before CSE is caught in noce_try_addcc. The second form
> obviously not (because we don't know that the value of i.20 is "i + 1").
>
> So this comes down to a pass ordering problem.
I'll just point out that the df merge allowed much better freedom in
pass ordering. Ifconv1 could be anticipated before CSE and fwprop.
Paolo
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30521
next prev parent reply other threads:[~2008-11-22 10:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-21 0:32 [Bug c++/30521] New: " sigra at home dot se
2007-01-21 8:54 ` [Bug middle-end/30521] " pinskia at gcc dot gnu dot org
2007-01-22 0:29 ` pinskia at gcc dot gnu dot org
2008-08-27 4:40 ` bonzini at gnu dot org
2008-08-27 4:40 ` bonzini at gnu dot org
2008-11-22 9:53 ` steven at gcc dot gnu dot org
2008-11-22 10:05 ` steven at gcc dot gnu dot org
2008-11-22 10:17 ` bonzini at gnu dot org [this message]
[not found] <bug-30521-4@http.gcc.gnu.org/bugzilla/>
2012-03-04 1:45 ` pinskia at gcc dot gnu.org
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