From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17723 invoked by alias); 13 Dec 2002 14:56:07 -0000 Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-prs-owner@gcc.gnu.org Received: (qmail 17660 invoked by uid 71); 13 Dec 2002 14:56:07 -0000 Date: Fri, 13 Dec 2002 06:56:00 -0000 Message-ID: <20021213145607.17655.qmail@sources.redhat.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, From: "Christian Ehrhardt" Subject: Re: optimization/7799: [3.2/3.3 regression] Loop bug with optimization flag -Os in gcc Reply-To: "Christian Ehrhardt" X-SW-Source: 2002-12/txt/msg00754.txt.bz2 List-Id: The following reply was made to PR optimization/7799; it has been noted by GNATS. From: "Christian Ehrhardt" To: Eric Botcazou 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 15:52:49 +0100 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!