From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 64001 invoked by alias); 18 Aug 2016 10:05:11 -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 63990 invoked by uid 89); 18 Aug 2016 10:05:10 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 spammy=theoretical, loosemore, Loosemore, HTo:U*sandra X-HELO: foss.arm.com Received: from foss.arm.com (HELO foss.arm.com) (217.140.101.70) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 18 Aug 2016 10:05:09 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 588E030C; Thu, 18 Aug 2016 03:06:41 -0700 (PDT) Received: from e105689-lin.cambridge.arm.com (e105689-lin.cambridge.arm.com [10.2.207.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 293C03F215; Thu, 18 Aug 2016 03:05:06 -0700 (PDT) Subject: Re: Fwd: [PATCH, doc/ARM] Remove false affirmation that Thumb cannot use an FPU To: Sandra Loosemore , Thomas Preudhomme , gcc-patches@gcc.gnu.org References: <4052511d-541d-9b8b-3000-ba09dc314f7f@foss.arm.com> <57ABEC64.3080104@codesourcery.com> <513df5b0-afba-bd3c-b2bb-ef7d67e1023b@foss.arm.com> <57B54F16.8080304@codesourcery.com> From: "Richard Earnshaw (lists)" Message-ID: <2210dcfd-6256-d62c-a782-f794238a55bf@arm.com> Date: Thu, 18 Aug 2016 10:05:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <57B54F16.8080304@codesourcery.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-SW-Source: 2016-08/txt/msg01321.txt.bz2 On 18/08/16 07:00, Sandra Loosemore wrote: > On 08/11/2016 04:31 AM, Thomas Preudhomme wrote: > >> diff --git a/gcc/doc/fragments.texi b/gcc/doc/fragments.texi >> index >> b6d8541c8ca820fa732363a05221e2cd4d1251c2..abf4e128671bb4751d21f24bb69625593d3c839e >> 100644 >> --- a/gcc/doc/fragments.texi >> +++ b/gcc/doc/fragments.texi >> @@ -117,12 +117,15 @@ specified, there are combinations that should >> not be built. In that >> case, set @code{MULTILIB_EXCEPTIONS} to be all of the switch exceptions >> in shell case syntax that should not be built. >> >> -For example the ARM processor cannot execute both hardware floating >> -point instructions and the reduced size THUMB instructions at the same >> -time, so there is no need to build libraries with both of these >> -options enabled. Therefore @code{MULTILIB_EXCEPTIONS} is set to: >> +For example on ARM targets @option{-mfloat-abi=soft} requests to use a >> +softfloat implementation for floating-point operations. Therefore, it >> +does not make sense to find both @option{-mfloat-abi=soft} and an >> +@option{mfpu} option on the command line so @code{MULTILIB_EXCEPTIONS} >> +could contain the following exception (assuming that >> +@option{-mfloat-abi} comes after in @code{MULTILIB_OPTIONS} and given >> +that @option{-mfloat-abi=soft} is the default value): >> @smallexample >> -*mthumb/*mhard-float* >> +*mfpu=* >> @end smallexample >> >> @findex MULTILIB_REQUIRED > > This version still has a lot of copy-editing issues. I suggest > rewriting as: > > For example, on ARM targets @option{-mfloat-abi=soft} requests use of > software floating-point operations, so it > does not make sense to build libraries with both > @option{-mfloat-abi=soft} and an @option{-mfpu} option. > @code{MULTILIB_EXCEPTIONS} could contain the following exception > > but here I get stuck in suggesting a rewrite, because I can't parse this > part at all to figure out what you're trying to say: > > (assuming that > @option{-mfloat-abi} comes after in @code{MULTILIB_OPTIONS} and given > that @option{-mfloat-abi=soft} is the default value): > > "comes after in"? Comes after what? If the order is important here, > the documentation should explain why instead of just "assuming" things > about it. > > -Sandra the confused > I think it's probably best to just drop the entire parenthetical subcluase. This is documentation of how to use MULTILIB_EXCEPTIONS not precise documentation on what needs to be done on ARM. In fact, it might be better to just rewrite the whole section based on a theoretical machine that has two ISAs, one which can support floating-point and one which can't. You then get back to essentially the same text as we had originally but anonymised and future proofed. R.