From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 96154 invoked by alias); 5 Nov 2015 17:09:51 -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 96145 invoked by uid 89); 5 Nov 2015 17:09:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: gate.crashing.org Received: from gate.crashing.org (HELO gate.crashing.org) (63.228.1.57) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Thu, 05 Nov 2015 17:09:49 +0000 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.13.8) with ESMTP id tA5H9ZRY030384; Thu, 5 Nov 2015 11:09:36 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id tA5H9XSK030377; Thu, 5 Nov 2015 11:09:33 -0600 Date: Thu, 05 Nov 2015 17:09:00 -0000 From: Segher Boessenkool To: Martin Sebor Cc: Alexander Monakov , Joseph Myers , Gcc Patch List Subject: Re: [PATCH] clarify documentation of -Q --help=optimizers Message-ID: <20151105170929.GA22951@gate.crashing.org> References: <56299713.6040204@gmail.com> <562997A9.3090203@gmail.com> <563A9A31.5060306@gmail.com> <563B7CA1.6080801@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <563B7CA1.6080801@gmail.com> User-Agent: Mutt/1.4.2.3i X-IsSubscribed: yes X-SW-Source: 2015-11/txt/msg00495.txt.bz2 On Thu, Nov 05, 2015 at 08:58:25AM -0700, Martin Sebor wrote: > I don't think that reiterating in a condensed form what the manual > doesn't make clear in many more words will help. First, even users > who do find the relevant text in the manual often misunderstand it. > Others are misled by the "[enabled]" output into expecting the > optimizations to take place at -O0. The -Q --help* output is primarily aimed at GCC developers, just like plain -Q is. The main problem here seems to be that the documentation pushes beginner GCC users to use this. Perhaps we should have a higher-level, more easy to use way to query what flags will do what, possibly integrated with the pass manager. > Those who are in doubt and > ask on gcc-help are then told by GCC experts that -O0 disables > all optimizations without exception, And it does, for the plain meaning of "optimization"; anything else is arguably a bug. But people have many different understandings of what a "compiler optimization" is, all the way to "anything the compiler does". Segher