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From: "stevenb at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/21173] [4.0/4.1 regression] miscompiled pointer subtraction broke Linux kernel
Date: Sun, 24 Apr 2005 09:23:00 -0000 [thread overview]
Message-ID: <20050424092349.30879.qmail@sourceware.org> (raw)
In-Reply-To: <20050423092333.21173.mikpe@csd.uu.se>
------- Additional Comments From stevenb at suse dot de 2005-04-24 09:23 -------
Subject: Re: [4.0/4.1 regression] miscompiled pointer subtraction broke Linux kernel
On Sunday 24 April 2005 05:36, dberlin at dberlin dot org wrote:
> Uh, because it causes things to become non-invariant when they were
> originally invariant (because it will *always* create a new name for
> them).
Well, the comment before force_gimple_operand says it should not:
/* Expands EXPR to list of gimple statements STMTS. If SIMPLE is true,
force the result to be either ssa_name or an invariant, otherwise
just force it to be a rhs expression. If VAR is not NULL, make the
base variable of the final destination be VAR if suitable. */
tree
force_gimple_operand (tree expr, tree *stmts, bool simple, tree var)
{
tree-ssa-pre uses force_gimple_operand with SIMPLE==false, so if
expr is already a valid rhs, force_gimple_operand should do nothing.
If it does, I consider that to be a bug.
Your patch to use unshare_expr is IMHO unnecessarily expensive.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21173
next prev parent reply other threads:[~2005-04-24 9:23 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-23 9:23 [Bug c/21173] New: " mikpe at csd dot uu dot se
2005-04-23 11:56 ` [Bug c/21173] " belyshev at depni dot sinp dot msu dot ru
2005-04-23 12:17 ` azarah at gentoo dot org
2005-04-23 12:30 ` [Bug tree-optimization/21173] [4.0 regression] " belyshev at depni dot sinp dot msu dot ru
2005-04-23 12:52 ` [Bug tree-optimization/21173] [4.0/4.1 " belyshev at depni dot sinp dot msu dot ru
2005-04-23 13:18 ` pinskia at gcc dot gnu dot org
2005-04-23 13:24 ` steven at gcc dot gnu dot org
2005-04-23 13:36 ` steven at gcc dot gnu dot org
2005-04-23 13:39 ` steven at gcc dot gnu dot org
2005-04-23 14:59 ` jakub at gcc dot gnu dot org
2005-04-23 15:09 ` dberlin at dberlin dot org
2005-04-23 15:13 ` dberlin at dberlin dot org
2005-04-23 17:19 ` azarah at gentoo dot org
2005-04-23 19:37 ` steven at gcc dot gnu dot org
2005-04-23 23:01 ` stevenb at suse dot de
2005-04-24 9:23 ` stevenb at suse dot de [this message]
2005-04-24 15:19 ` dberlin at gcc dot gnu dot org
2005-04-24 15:27 ` dberlin at dberlin dot org
2005-04-25 14:00 ` cvs-commit at gcc dot gnu dot org
2005-04-25 14:03 ` cvs-commit at gcc dot gnu dot org
2005-04-25 14:19 ` cvs-commit at gcc dot gnu dot org
2005-04-25 14:47 ` pinskia at gcc dot gnu dot org
2005-04-25 14:50 ` jakub at gcc dot gnu dot org
2005-04-25 15:18 ` dberlin at dberlin dot org
2005-04-26 12:36 ` dberlin at gcc dot gnu dot org
2005-04-28 2:35 ` belyshev at depni dot sinp dot msu dot ru
2005-04-28 23:38 ` cvs-commit at gcc dot gnu dot org
2005-05-10 17:32 ` pinskia at gcc dot gnu dot org
2005-05-10 22:31 ` pinskia at gcc dot gnu dot org
2005-05-11 10:51 ` pinskia at gcc dot gnu dot org
2005-05-17 11:35 ` pinskia at gcc dot gnu dot org
2005-05-18 6:05 ` pinskia at gcc dot gnu dot org
2005-05-22 18:47 ` pinskia at gcc dot gnu dot org
2005-06-12 13:24 ` pinskia at gcc dot gnu dot org
[not found] <bug-21173-7665@http.gcc.gnu.org/bugzilla/>
2006-03-22 20:54 ` pinskia at gcc dot gnu dot org
2006-03-28 17:40 ` pinskia at gcc dot gnu dot org
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