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From: "dberlin at dberlin dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/28778] [4.0/4.1/4.2 Regression] alias bug with cast and call clobbered
Date: Sun, 27 Aug 2006 04:12:00 -0000 [thread overview]
Message-ID: <20060827041210.10283.qmail@sourceware.org> (raw)
In-Reply-To: <bug-28778-1447@http.gcc.gnu.org/bugzilla/>
------- Comment #19 from dberlin at gcc dot gnu dot org 2006-08-27 04:12 -------
Subject: Re: [4.0/4.1/4.2 Regression] alias
bug with cast and call clobbered
rguenth at gcc dot gnu dot org wrote:
> ------- Comment #17 from rguenth at gcc dot gnu dot org 2006-08-26 20:42 -------
> So, making pointer arguments effectively using alias-set zero for alias and
> call clobbering computation would fix this.
>
Yes, if you change it so *everything passed to calls* is assumed to be
aliasing every variable with it's address taken, you will get the right
result in this case.
So what do you think will happen when you add one level of indirection
to the mess, and TBAA now prunes out *that* alias instead, so you miss
it again? (IE break the chain of clobber transitivity one link in the
other direcftion).
IMHO, i'd rather just see this bug, which has been in our compiler for 3
releases now, fixed properly in the next one, than hacked around.
It's relatively easy to fix this testcase in some hacky way, but i'm not
sure why we'd want to, when we know it will only fix this testcase, and
not the underlying problem.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28778
next prev parent reply other threads:[~2006-08-27 4:12 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-18 21:07 [Bug tree-optimization/28778] New: strict-aliasing bug mrs at apple dot com
2006-08-18 21:11 ` [Bug tree-optimization/28778] " pinskia at gcc dot gnu dot org
2006-08-18 21:12 ` mrs at apple dot com
2006-08-18 21:15 ` pinskia at gcc dot gnu dot org
2006-08-18 21:18 ` [Bug tree-optimization/28778] [4.0/4.1/4.2 Regression] alias bug with cast and call clobbered pinskia at gcc dot gnu dot org
2006-08-19 10:15 ` rguenth at gcc dot gnu dot org
2006-08-19 10:44 ` rguenth at gcc dot gnu dot org
2006-08-19 14:10 ` dberlin at gcc dot gnu dot org
2006-08-19 14:27 ` rguenth at gcc dot gnu dot org
2006-08-20 22:53 ` mmitchel at gcc dot gnu dot org
2006-08-21 1:34 ` dberlin at dberlin dot org
2006-08-21 16:34 ` janis at gcc dot gnu dot org
2006-08-25 19:57 ` drow at gcc dot gnu dot org
2006-08-25 20:51 ` drow at gcc dot gnu dot org
2006-08-25 20:57 ` drow at gcc dot gnu dot org
2006-08-25 22:12 ` drow at gcc dot gnu dot org
2006-08-26 15:15 ` drow at gcc dot gnu dot org
2006-08-26 20:30 ` rguenth at gcc dot gnu dot org
2006-08-26 20:42 ` rguenth at gcc dot gnu dot org
2006-08-26 23:25 ` drow at gcc dot gnu dot org
2006-08-27 4:12 ` dberlin at dberlin dot org [this message]
2006-08-27 14:20 ` rguenth at gcc dot gnu dot org
2006-08-27 15:41 ` dberlin at dberlin dot org
2006-08-27 15:50 ` rguenth at gcc dot gnu dot org
2006-08-27 16:00 ` dberlin at dberlin dot org
2006-08-27 17:56 ` drow at gcc dot gnu dot org
2006-08-27 20:25 ` mmitchel at gcc dot gnu dot org
2006-08-27 20:28 ` mmitchel at gcc dot gnu dot org
2006-08-27 20:51 ` dberlin at dberlin dot org
2006-08-27 21:09 ` dberlin at dberlin dot org
2006-08-28 8:43 ` rguenth at gcc dot gnu dot org
2006-09-09 17:55 ` dberlin at dberlin dot org
2006-09-16 18:09 ` steven at gcc dot gnu dot org
2006-09-16 20:03 ` dberlin at dberlin dot org
2006-09-26 4:44 ` acahalan at gmail dot com
2006-09-26 4:56 ` Andrew Pinski
2006-09-26 4:56 ` pinskia at physics dot uc dot edu
2006-09-26 14:17 ` acahalan at gmail dot com
2006-09-26 14:32 ` pinskia at gcc dot gnu dot org
2006-09-26 15:33 ` acahalan at gmail dot com
2006-09-26 15:47 ` dberlin at dberlin dot org
2006-09-26 15:49 ` pinskia at gcc dot gnu dot org
2006-09-26 15:57 ` pcarlini at suse dot de
2006-09-27 2:12 ` dberlin at dberlin dot org
2006-10-13 17:50 ` dberlin at gcc dot gnu dot org
2006-10-19 23:06 ` dberlin at gcc dot gnu dot org
2006-10-19 23:07 ` dberlin at gcc dot gnu dot org
2006-10-20 8:25 ` [Bug tree-optimization/28778] [4.0/4.1 " rguenth at gcc dot gnu dot org
2006-11-05 22:17 ` chuck at vertica dot com
2006-11-05 22:26 ` pinskia at gcc dot gnu dot org
2006-11-05 22:26 ` drow at gcc dot gnu dot org
2006-11-05 23:39 ` chuck at vertica dot com
2007-01-25 15:51 ` gdr at gcc dot gnu dot org
2007-02-07 22:52 ` pinskia at gcc dot gnu dot org
2007-02-14 9:09 ` mmitchel at gcc dot gnu dot org
2008-07-04 15:51 ` [Bug tree-optimization/28778] [4.1 " jsm28 at gcc dot gnu dot org
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