From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 41699 invoked by alias); 1 Apr 2016 09:19:15 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 41683 invoked by uid 89); 1 Apr 2016 09:19:14 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=HX-Greylist:Fri, HX-Greylist:Apr 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 (AES256-GCM-SHA384 encrypted) ESMTPS; Fri, 01 Apr 2016 09:19:13 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CED967109D; Fri, 1 Apr 2016 09:19:11 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-113-22.phx2.redhat.com [10.3.113.22]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u319JAkL012334 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 1 Apr 2016 05:19:11 -0400 Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.15.2/8.15.2) with ESMTP id u319J8n3027806; Fri, 1 Apr 2016 11:19:08 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.15.2/8.15.2/Submit) id u319J6DD027805; Fri, 1 Apr 2016 11:19:06 +0200 Date: Fri, 01 Apr 2016 09:19:00 -0000 From: Jakub Jelinek To: Richard Biener Cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH] Fix PR70484, RTL DSE using wrong dependence check Message-ID: <20160401091906.GR3017@tucnak.redhat.com> Reply-To: Jakub Jelinek References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-IsSubscribed: yes X-SW-Source: 2016-04/txt/msg00010.txt.bz2 On Fri, Apr 01, 2016 at 11:08:09AM +0200, Richard Biener wrote: > > RTL DSE uses true_dependence to see whether a store may be killed by > anothe store - that's obviously broken. The following patch makes > it use output_dependence instead (introducing a canon_ variant of that). I think it would be interesting to see some stats on what effect does this have on the optimization RTL DSE is doing (say gather during unpatched bootstrap/regtest number of successfully optimized replace_read calls, and the same with patched bootstrap/regtest). >From quick look at the patch, this wouldn't optimize even the cases that could be optimized (return *pi;) at the RTL level. If the statistics would show this affects it significantly, perhaps we could do both canon_true_dependence and canon_output_dependence, and if the two calls differ, don't clear the rhs, but mark it somehow and then in replace_read check what alias set is used for the read or something similar? Jakub