From: "Christian Ehrhardt" <ehrhardt@mathematik.uni-ulm.de>
To: Eric Botcazou <ebotcazou@libertysurf.fr>
Cc: nejataydin@superonline.com, gcc-gnats@gcc.gnu.org,
gcc@gcc.gnu.org, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org
Subject: Re: optimization/7799: [3.2/3.3 regression] Loop bug with optimization flag -Os in gcc
Date: Fri, 13 Dec 2002 07:34:00 -0000 [thread overview]
Message-ID: <20021213145249.20337.qmail@thales.mathematik.uni-ulm.de> (raw)
In-Reply-To: <200212131449.01528.ebotcazou@libertysurf.fr>
On Fri, Dec 13, 2002 at 02:49:01PM +0100, Eric Botcazou wrote:
> > This transformation is IMHO illegal because there is no way to make the
> > comparison in general equivialent to that in the original for loop.
> > If p is initially 0x7ffffffc the comparison must be treated as unsigned,
> > however, if p is initially 0xfffffffc the comparison must be treated as
> > signed.
>
> Well-known deficiency of the strength reduction pass (see the testcase
> testsuite/gcc.c-torture/execute/loop-2e.c which is XFAILed on x86 at -Os).
Thanks for the clarification. This means that we can close the report?
I can confirm that using -fno-strength-reduce fixes the problem.
regards Christian
--
THAT'S ALL FOLKS!
next prev parent reply other threads:[~2002-12-13 14:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-13 5:57 Christian Ehrhardt
2002-12-13 6:13 ` Eric Botcazou
2002-12-13 7:34 ` Christian Ehrhardt [this message]
2002-12-13 10:28 ` Eric Botcazou
2002-12-13 6:52 ` Andrew Haley
2002-12-13 7:35 ` Christian Ehrhardt
2002-12-13 7:44 ` Andreas Schwab
2002-12-19 22:52 ` Segher Boessenkool
2002-12-20 5:46 ` Christian Ehrhardt
2002-12-20 1:24 Joern Rennecke
2002-12-20 21:08 Robert Dewar
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