From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19002 invoked by alias); 6 May 2014 08:24:56 -0000 Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org Received: (qmail 18991 invoked by uid 89); 6 May 2014 08:24:55 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.9 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 06 May 2014 08:24:54 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s468Orkh010347 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 6 May 2014 04:24:53 -0400 Received: from oldenburg.str.redhat.com (oldenburg.str.redhat.com [10.33.200.60]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s468OqkW017407 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 6 May 2014 04:24:53 -0400 Message-ID: <53689C53.2050603@redhat.com> Date: Tue, 06 May 2014 08:24:00 -0000 From: Florian Weimer User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Jeff Law , "gcc-help@gcc.gnu.org" Subject: Re: Target dependence of conditional expression gimplification References: <53146FAA.8090802@redhat.com> <5367A8BF.5010805@redhat.com> <5367B81F.9020401@redhat.com> In-Reply-To: <5367B81F.9020401@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2014-05/txt/msg00020.txt.bz2 On 05/05/2014 06:11 PM, Jeff Law wrote: > Yes, this is a known issue. There's places where the costing models > change the gimple we initially generate and what transformations we > apply later. Well, "known issue" is very subjective. Our developers run into this quite regularly because you get more -Wstrict-overflow warnings on ppc64 and s390x than on x86_64. The GIMPLE on x86_64 contains fewer conditional statements, so the warning does not fire. > Long term we want to push this stuff to a later point in the pipeline, > but there's some disagreement over exactly how/when to do that. Would it be feasible (for someone like me who is not really familiar with GCC internals) to move the BRANCH_COST-dependent bits of fold to an early GIMPLE pass? There's another target dependence related to function pointers which could receive similar treatment. This wouldn't help with the -Wstrict-overflow issue that prompted my original message, but it would benefit warnings and other analyses performed on early not-fully-optimized GIMPLE. -- Florian Weimer / Red Hat Product Security Team