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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/56415] [4.8 Regression] Performance regression after fix for 56273
Date: Thu, 21 Feb 2013 10:45:00 -0000 [thread overview]
Message-ID: <bug-56415-4-26hLcxdLsY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-56415-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56415
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |4.8.0
Summary|Performance regression |[4.8 Regression]
|after fix for 56273 |Performance regression
| |after fix for 56273
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2013-02-21 10:44:38 UTC ---
Ok, the fact is that with changes like
@@ -917,7 +839,7 @@
_201 = *_111[_200];
t[6] = _201;
_206 = _108;
- if (_108 == 8)
+ if (_108 > 7)
goto <bb 18>;
@@ -906,7 +828,7 @@
_187 = *_111[_186];
t[5] = _187;
_192 = _108;
- if (_108 != 6)
+ if (_108 > 6)
goto <bb 17>;
else
goto <bb 7>;
we weaken range information on one code-path but improve it on another.
We should be still able to figure out the original ranges though, so
this change probably only papered over the other PR.
I'll revert that change.
next prev parent reply other threads:[~2013-02-21 10:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-21 8:55 [Bug tree-optimization/56415] New: " ysrumyan at gmail dot com
2013-02-21 8:59 ` [Bug tree-optimization/56415] " ysrumyan at gmail dot com
2013-02-21 9:11 ` ysrumyan at gmail dot com
2013-02-21 9:46 ` rguenth at gcc dot gnu.org
2013-02-21 10:45 ` rguenth at gcc dot gnu.org [this message]
2013-02-21 10:53 ` [Bug tree-optimization/56415] [4.8 Regression] " rguenth at gcc dot gnu.org
2013-02-21 10:53 ` rguenth at gcc dot gnu.org
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