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From: "davidxl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/46200] [4.6 Regression] optimization regression in simple pointer loop
Date: Thu, 28 Oct 2010 19:01:00 -0000	[thread overview]
Message-ID: <20101028190100.cB0dVYX6JLLSvTAbnRCsG589CgpIwsMszZMC_3aIviE@z> (raw)
In-Reply-To: <bug-46200-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46200

davidxl <davidxl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |davidxl at gcc dot gnu.org

--- Comment #5 from davidxl <davidxl at gcc dot gnu.org> 2010-10-28 19:01:16 UTC ---
Confirmed.

The problem seems to be in the cost computation for loop exit tests -- the cost
associated with iv update seem to be double counted (already considered as iv
cost, but included again in testing cost). If this is the root cause, it is
there since day-1, but exposed by the ivopt enhancement patch.

David


  parent reply	other threads:[~2010-10-28 19:01 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-27 16:57 [Bug rtl-optimization/46200] New: " miles at gnu dot org
2010-10-28 14:53 ` [Bug target/46200] [4.6 Regression] " rguenth at gcc dot gnu.org
2010-10-28 17:14 ` hjl.tools at gmail dot com
2010-10-28 17:43 ` pinskia at gcc dot gnu.org
2010-10-28 17:54 ` hjl.tools at gmail dot com
2010-10-28 19:01 ` davidxl at gcc dot gnu.org [this message]
2010-11-03 22:41 ` davidxl at gcc dot gnu.org

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