From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 46442 invoked by alias); 25 Sep 2015 14:34:55 -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 46431 invoked by uid 89); 25 Sep 2015 14:34:54 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.3 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD autolearn=no version=3.3.2 X-HELO: nikam.ms.mff.cuni.cz Received: from nikam.ms.mff.cuni.cz (HELO nikam.ms.mff.cuni.cz) (195.113.20.16) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Fri, 25 Sep 2015 14:34:53 +0000 Received: by nikam.ms.mff.cuni.cz (Postfix, from userid 16202) id F3E0D542C51; Fri, 25 Sep 2015 16:34:48 +0200 (CEST) Date: Fri, 25 Sep 2015 14:54:00 -0000 From: Jan Hubicka To: Teresa Johnson Cc: Bernd Schmidt , "gcc-patches@gcc.gnu.org" , Jan Hubicka , Xinliang David Li Subject: Re: [PATCH] Disable -fno-reorder-blocks-and-partition if no -fprofile-use to avoid unnecessary overhead Message-ID: <20150925143447.GI59241@kam.mff.cuni.cz> References: <56055316.6080901@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-SW-Source: 2015-09/txt/msg01968.txt.bz2 > > What has changed between then and now? Also, do we not use > > estimates/heuristics when not using a profile? > > Nothing has changed - splitting effectively never kicked in without a > profile. Honza and I had discussed the idea that static profile > heuristics could eventually be used to distinguish hot vs cold bbs, Yep, the basic idea was to move EH clenaups to the cold section for start. The cleanup code can get surprisingly large for some C++ apps. > but that hasn't happened. What I didn't notice until recently was the > size increase in the .o files from varasm adding in unnecessary > sections and labels when this option was on. Unless and until static Perhaps we also may just teach varasm to not output those when function is not split. I am happy with the patch as it is because it is pointless to run the code when no splitting happens. Honza > heuristics are used to distinguish cold bbs in > probably_never_executed_bb_p, I don't think it makes sense to do > anything finer grained that just disabling the option. > > Teresa > > > > > > > Bernd > > > > -- > Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413