From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qv1-xf34.google.com (mail-qv1-xf34.google.com [IPv6:2607:f8b0:4864:20::f34]) by sourceware.org (Postfix) with ESMTPS id 6BF0A3858D37 for ; Thu, 6 Oct 2022 18:42:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6BF0A3858D37 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-qv1-xf34.google.com with SMTP id z18so1735837qvn.6 for ; Thu, 06 Oct 2022 11:42:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=QIpokF/w2AIBwO2F9UwDnSeBzNQuCWA3AkeitMX/p6U=; b=FF/yl0r1AHQPV44oBw2gPxeNWDTHsIYdmqOWtD/mRKOCcTnEOmdb6Ec06yYi5V8tNy pju+FVbLYeoTY05h40W4R2emf+U+x4m5BxaKbA6o9qBsM30k1D3IZxYMcbdNFHLxe6J0 FogXci17+4o+qUjyCVcEXF+aIFi7b++WEhXa8nx7yAHSWXoCSkMPtDQHFXF8dIlNkGfA hcQZT33o8aDI/p1oN9Q31GTo5TMreTneA2+0uVxC0wI5xUOCKvAt/rphaj8FHcUZCcnR ttUm7DWQ346wY4yrpg9JMUQdmRN3QwvcupnmX/bccMsJ8XVI4u/2F+j1u0O7hXedTiWb 8E8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=QIpokF/w2AIBwO2F9UwDnSeBzNQuCWA3AkeitMX/p6U=; b=KqXIskTkqUWLGJZNNDLZrqb8ezm4NHumqOOz0Nk3gwgzhtNxmEysv6lC3Uv6c7vFAK HvlsGL7wxy81scGC/2KPTTYYUmZeVmbvI7XFmZ2hBnbyqAaYsfKkZ8vSN7VX9VJfrgCF RjR+XLBNIXDsXIvi10Ltg6LjLckPGMeblr5cX7U0sr7juWvos7ANlnw3To1ZCS8DsGiX AiWueM8G4wnPSJCsoQG02caUCBZl/llRgDPchoX5Rl3QOBm7AenxelAeDwGRTUsDvSmE cNvfT3KyrOtwIlRgdnavVwXY8DDmK1jLORuwtax2s/Nu6CJ8mZJjpyNJkyd9I5Pc5Upx CVVA== X-Gm-Message-State: ACrzQf2ZGYVe9L4UTPHgX5xgE16GeBYlMe7gCnRWC89eUJNkP/Jb9czd xx8VfMDdziMv+MkV1GoTZSd5SrXuwvtzR4tKG8g= X-Google-Smtp-Source: AMsMyM6C8qK+E90esZeW/vWHCX3zC+ogVdvmjAofF55gKCsFQ3G+7D8M8nAiBCpHS1L1cxCzfZuB6+RaMIan4sA2DOU= X-Received: by 2002:ad4:4ee4:0:b0:4b1:d60b:c830 with SMTP id dv4-20020ad44ee4000000b004b1d60bc830mr1315819qvb.84.1665081726677; Thu, 06 Oct 2022 11:42:06 -0700 (PDT) MIME-Version: 1.0 References: <20e2773a-2e47-869b-1900-709f8ad4cd6b@suse.com> <9f97da22-8125-ed4e-6def-ef14ca170b51@suse.com> <2c52318b-c398-9f3a-ccbe-135caa6b3e2d@suse.com> In-Reply-To: From: "H.J. Lu" Date: Thu, 6 Oct 2022 11:41:30 -0700 Message-ID: Subject: Re: [PATCH v3 3/7] x86: re-work insn/suffix recognition To: Jan Beulich Cc: Binutils Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3018.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Thu, Oct 6, 2022 at 9:12 AM Jan Beulich wrote: > > On 06.10.2022 17:28, H.J. Lu wrote: > > On Wed, Oct 5, 2022 at 11:58 PM Jan Beulich wrote: > >> > >> On 06.10.2022 08:15, Jan Beulich via Binutils wrote: > >>> On 06.10.2022 01:52, H.J. Lu wrote: > >>>> Does the new assembler work on Linux kernel which has "rep movsd"? > >>> > >>> No. And it shouldn't, as they should never have used MOVSD. The only valid > >>> mnemonic (in AT&T syntax) is MOVSL. If you're meaning to suggest that we > >>> continue to support MOVSD in AT&T mode, then this will - once again for > >>> consistency - need extending to _all_ other D-suffixable insns the SDM > >>> specifies. I can only repeat what I've said before: Consistency is a > >>> requirement such that users can predict assembler behavior. > >> > >> Note how Clang's integrated assembler doesn't even support CMPSD as a > >> string instruction - that's imo yet more odd behavior, and likely > >> attributed _solely_ to the goal of wanting to work around code wrongly > >> using such. > > > > I think we should avoid changing assembly sources if possible. Should we keep > > CMPSD/MOVSD without any operands? This won't cause any confusion. > > Since Clang doesn't support CMPSD, I'd be (hesitantly) okay with keeping > just the single MOVSD template having no operands. I'm still be inclined > to warn if it ends up being used, so that people can correct their code. > If you can explain why you think CMPSD also needs retaining in a similar > way, I might be talked into keeping the operand-less form there as well. > But anything going beyond that would have me fall back to requiring > consistency throughout the mnemonics a D suffix might be used with as > per vendor documentation. Warning is fine with me. We should accept MOVSD and CMPSD without operands. -- H.J.