From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32644 invoked by alias); 24 Aug 2018 19:15:04 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 32588 invoked by uid 89); 24 Aug 2018 19:15:02 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy=go, aggressively, Hx-languages-length:1792 X-HELO: smtp.polymtl.ca Received: from smtp.polymtl.ca (HELO smtp.polymtl.ca) (132.207.4.11) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 24 Aug 2018 19:15:00 +0000 Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id w7OJEsV7017255 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 24 Aug 2018 15:14:59 -0400 Received: by simark.ca (Postfix, from userid 112) id 1750C1EB43; Fri, 24 Aug 2018 15:14:54 -0400 (EDT) Received: from simark.ca (localhost [127.0.0.1]) by simark.ca (Postfix) with ESMTP id 3CEFA1E012; Fri, 24 Aug 2018 15:14:50 -0400 (EDT) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 24 Aug 2018 19:15:00 -0000 From: Simon Marchi To: Pedro Alves Cc: Kevin Buettner , gdb-patches@sourceware.org, Joel Brobecker Subject: Re: GDB 8.2 release 2018-08-21 status update In-Reply-To: References: <20180821175136.GA3365@adacore.com> <0e24ffbeb9706f75c53d3fdcfea3decb@polymtl.ca> <20180823154138.66be5572@pinnacle.lan> Message-ID: X-Sender: simon.marchi@polymtl.ca User-Agent: Roundcube Webmail/1.3.6 X-IsSubscribed: yes X-SW-Source: 2018-08/txt/msg00599.txt.bz2 On 2018-08-24 14:35, Pedro Alves wrote: > On 08/23/2018 11:41 PM, Kevin Buettner wrote: >> Simon Marchi wrote: > >>> So from my point of view, it would be fine to include it in 8.2. I'm >>> just wondering though why this was considered as a blocker for 8.2 in >>> the first place. It's not really a regression, it's more like a new >>> feature. Was it to make sure we get the feature to users faster, >>> before >>> the new gcc that emits code like this by default starts to spread too >>> much? > > Yeah, the main issue here is that nowadays > -freorder-blocks-and-partition > is on by default in GCC (I believe the switch was flipped in GCC 8?), > which > means users will run into this problem more frequently going forward. > While > technically it's not a GDB regression (you can always run into this if > you > build your program with -freorder-blocks-and-partition explicitly), > from > the perspective of end users looking at the toolchain as whole black > box, > it's a toolchain regression (defaults no longer work). > I'd support putting the series in GDB 8.2. Seems nobody is against it. Go! > Unless I'm wrong that > -freorder-blocks-and-partition is on by default in GCC 8 already? Looking at gcc/doc/invoke.texi, apparently it's been enabled for -O2/-O3 for some time and more recently -Os. You can check whether it is enabled with: gcc -Q -v --help 2>/dev/null | grep reorder-blocks-and-partition I see it as disabled by default and enabled if I add -O2, with different gcc versions between 5.4.0 and 8.2.0. So it doesn't seem to have changed recently. Maybe what changed is that gcc 8 partitions more aggressively? Or it's just that gcc developers tend to debug -O2 builds? I have no idea. Simon