From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 87732 invoked by alias); 13 Nov 2015 11:32:19 -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 87723 invoked by uid 89); 13 Nov 2015 11:32:19 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.2 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx2.suse.de Received: from mx2.suse.de (HELO mx2.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (CAMELLIA256-SHA encrypted) ESMTPS; Fri, 13 Nov 2015 11:32:18 +0000 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 71A42AD17; Fri, 13 Nov 2015 11:31:52 +0000 (UTC) Date: Fri, 13 Nov 2015 11:32:00 -0000 From: Richard Biener To: VandeVondele Joost cc: "hiraditya@gmail.com" , "sebpop@gmail.com" , "gcc-patches@gcc.gnu.org" Subject: Re: [PATCH] RFC: Enable graphite at -O3 -fprofile_use In-Reply-To: <908103EDB4893A42920B21D3568BFD9339F0AD26@MBX13.d.ethz.ch> Message-ID: References: <908103EDB4893A42920B21D3568BFD9339F0AD26@MBX13.d.ethz.ch> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SW-Source: 2015-11/txt/msg01671.txt.bz2 On Fri, 13 Nov 2015, VandeVondele Joost wrote: > I'm all in favour of requiring isl and enabling graphite by default, but > would suggest to enable it with -Ofast instead. > > One reason is that certainly extracting testcases from a PGO build is > more difficult, and initially there will certainly be miscompiles with > graphite (CP2K is right now). > > Furthermore, unless graphite is particularly effective with PGO (does it > use average loop trip counts already?), I don't see a particular > connection. The reason to choose FDO was so GRAPHITE can concentrate its computing budget on the hot parts of a program (which profile estimation isn't good enough identifying), reducing its compile-time cost. -Ofast isn't supposed to enable passes over -O3 so you're suggesting to enable it with -O3 which I think is a bit premature. But we can try doing that and revert at the end of stage3 if problems are just too big. Richard.