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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/26944] [4.1/4.2 Regression] -ftree-ch generates worse code
Date: Thu, 04 May 2006 21:25:00 -0000	[thread overview]
Message-ID: <20060504212551.14489.qmail@sourceware.org> (raw)
In-Reply-To: <bug-26944-1008@http.gcc.gnu.org/bugzilla/>



------- Comment #9 from pinskia at gcc dot gnu dot org  2006-05-04 21:25 -------
(In reply to comment #8)
> WRT this code generated by tree-ch:
>   D.1305_41 = Int_Loc_3 + 1;
>   if (Int_Loc_3 <= D.1305_41) goto <L0>; else goto <L2>;
> 
> AFAICT there's exactly one value for which the comparison can be false, IMO it
> would be better to test directly that value instead of generating a new SSA
> name and another expression.

Well CH should not do this as it never sees two expressions together, only the
one COND_EXPR.  If we do a VRP after CH, it will not fix it currently either
because VRP does not record that many symbolic ranges (I forgot that PR number,
it was filed by me). If VRP did that and we added a VRP after CH but before
IV-OPTS, maybe this wil fix itself.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26944


  parent reply	other threads:[~2006-05-04 21:25 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-30 16:15 [Bug tree-optimization/26944] New: " dann at godzilla dot ics dot uci dot edu
2006-03-30 16:25 ` [Bug tree-optimization/26944] [4.1/4.2 Regression] " rguenth at gcc dot gnu dot org
2006-03-30 16:43 ` dann at godzilla dot ics dot uci dot edu
2006-03-31 22:41   ` Daniel Berlin
2006-03-31 22:41 ` dberlin at dberlin dot org
2006-04-02  8:12 ` pinskia at gcc dot gnu dot org
2006-04-16 19:13 ` mmitchel at gcc dot gnu dot org
2006-05-02 17:38 ` steven at gcc dot gnu dot org
2006-05-03 18:55 ` dann at godzilla dot ics dot uci dot edu
2006-05-03 19:00   ` Andrew Pinski
2006-05-03 19:00 ` pinskia at physics dot uc dot edu
2006-05-03 21:33 ` steven at gcc dot gnu dot org
2006-05-03 21:53 ` dann at godzilla dot ics dot uci dot edu
2006-05-04 21:25 ` pinskia at gcc dot gnu dot org [this message]
2006-05-25  2:39 ` mmitchel at gcc dot gnu dot org
2007-02-14  9:10 ` [Bug tree-optimization/26944] [4.1/4.2/4.3 " mmitchel at gcc dot gnu dot org
2007-06-18  5:28 ` [Bug tree-optimization/26944] [4.1/4.2 " pinskia at gcc dot gnu dot org
2008-07-04 20:22 ` [Bug tree-optimization/26944] [4.2 " jsm28 at gcc dot gnu dot org
2009-03-30 15:51 ` jsm28 at gcc dot gnu dot org

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