From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 123320 invoked by alias); 13 Feb 2020 16:45:36 -0000 Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org Received: (qmail 123178 invoked by uid 89); 13 Feb 2020 16:45:30 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.1 spammy=H*i:sk:be9f444, H*f:sk:be9f444, H*RU:209.85.167.193, HX-Spam-Relays-External:209.85.167.193 X-HELO: mail-oi1-f193.google.com Received: from mail-oi1-f193.google.com (HELO mail-oi1-f193.google.com) (209.85.167.193) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 13 Feb 2020 16:45:27 +0000 Received: by mail-oi1-f193.google.com with SMTP id a142so6407053oii.7 for ; Thu, 13 Feb 2020 08:45:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=L2ua39eGVeR6Xr+f+cZ121PDjJH9MIeEJE/0kh1gV/s=; b=LloiNHHWmOHh4R0qPeoGbgYq+Rys1Idj4F1IojqvBjJD+TphmxPdiyuTnp4EbduS5c XGQnEp80gTMDpfxLxTkO8wLL2c9xAVGFMQQu84Gyi2SZp03+34iYnXmjLtbu3WJitm8U gdTGw8K/0lDzv7OCgfmIvG6hcYv7OhF9khT6IgJWMvBlDOc1NNlnxhxnfr4JDWGtPKCr zK7PkfSFi800np7ERpDbpin5cZx/3/qPEEv1UL0KoMI4qB3eArvYW/wdyNjszgJlr1KL ENTJXCxW2wtz1VimdAzgLtCm8dnLKSiddd2S+ywc/XWyg0ViLEfpVd7Y8UUNxEVXxUgv 0P3g== MIME-Version: 1.0 References: <20d349db-7e31-294b-cefb-f22265d8bff2@suse.com> <5a4cb285-3d1a-8842-8b4b-94423a37e8d0@suse.com> <801b535a-f10f-c99a-9c0e-ea88561a5c71@suse.com> <524774f0-21e3-857a-55b1-69d4d4334d80@suse.com> In-Reply-To: From: "H.J. Lu" Date: Thu, 13 Feb 2020 16:45:00 -0000 Message-ID: Subject: Re: [PATCH 1/3] x86: extend LEA's segment override warning To: Jan Beulich Cc: "binutils@sourceware.org" Content-Type: text/plain; charset="UTF-8" X-IsSubscribed: yes X-SW-Source: 2020-02/txt/msg00293.txt.bz2 On Thu, Feb 13, 2020 at 8:38 AM Jan Beulich wrote: > > On 13.02.2020 17:31, H.J. Lu wrote: > > On Thu, Feb 13, 2020 at 8:00 AM Jan Beulich wrote: > >> > >> On 13.02.2020 16:51, H.J. Lu wrote: > >>> On Thu, Feb 13, 2020 at 6:48 AM Jan Beulich wrote: > >>>> > >>>> On 13.02.2020 15:11, H.J. Lu wrote: > >>>>> On Thu, Feb 13, 2020 at 6:05 AM Jan Beulich wrote: > >>>>>> > >>>>>> For one both possible forms should be warned about. And then there are > >>>>>> a couple of MPX insns behaving LEA-like, which should be warned about in > >>>>>> the same way. Finally, to guard against future surprises, qualify the > >>>>>> original opcode check by excluding VEX/EVEX-like templates. > >>>>>> > >>>>>> gas/ > >>>>>> 2020-02-XX Jan Beulich > >>>>>> > >>>>>> * config/tc-i386.c (process_operands): Also check insn prefix > >>>>>> for ineffectual segment override warning. Also cover BNDC* and > >>>>>> BNDMK there. Don't cover possible VEX/EVEX encoded insns there. > >>>>>> * testsuite/gas/i386/lea.s, testsuite/gas/i386/lea.d, > >>>>>> testsuite/gas/i386/lea.e: New. > >>>>>> * testsuite/gas/i386/i386.exp: Run new test. > >>>>>> > >>>>> > >>>>> Why should it be warning, not error? > >>>> > >>>> Because the code isn't wrong, just inefficient. I also don't think > >>>> converting from warning to error should be done in the same patch > >>>> as extending the coverage of what gets a diagnostic emitted. > >>> > >>> What do we gain to allow it? > >> > >> It has always been allowed, and in one of the two cases even silently. > >> We're liable to break people's working code if we changed this. > > > > Given that MPX has been deprecated, MPX codes are very unlikely to > > change. Assembler shouldn't bother with this. > > What a strange position to take. Anyway, are you saying the change is > going to be okay if I remove the MPX aspects from it? (It is only > this 3rd reply of yours where you mention MPX, so I'm a little > puzzled.) > Yes. -- H.J.