From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE14AC4363D for ; Fri, 25 Sep 2020 09:18:13 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 16324206E5 for ; Fri, 25 Sep 2020 09:18:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="L91FId8N" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16324206E5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45392 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLjrn-0008Pt-TO for qemu-devel@archiver.kernel.org; Fri, 25 Sep 2020 05:18:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57970) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLjrE-00080r-2S for qemu-devel@nongnu.org; Fri, 25 Sep 2020 05:17:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:28512) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kLjrC-00005k-7B for qemu-devel@nongnu.org; Fri, 25 Sep 2020 05:17:35 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601025453; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=KXB3T9Xtk0NwFng/841U/BVwzUN8ft2jsMT5UuUuNa0=; b=L91FId8N1hSHBpyZJc/kA4q/8VgiL/zZKBWghxhMzGo/b2cI7MoOasNTU8IFwO6zR68aGR CsEQD+dqDel10Fj4j96xrnO/BXVysg6MI+vJH7U41N4Ysc5DmJArEZzM1rmvjWxpp3SaQX 36ZGsdu7zeDA7WQ9upt+Nr8FKEQ+quo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-283-AUvyWpouPEmiK2VDTI2Sew-1; Fri, 25 Sep 2020 05:17:31 -0400 X-MC-Unique: AUvyWpouPEmiK2VDTI2Sew-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8A48987A831; Fri, 25 Sep 2020 09:17:30 +0000 (UTC) Received: from [10.36.112.211] (ovpn-112-211.ams2.redhat.com [10.36.112.211]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3D4D87367E; Fri, 25 Sep 2020 09:17:29 +0000 (UTC) Subject: Re: [PATCH 6/8] softfloat: Implement float128_muladd To: Richard Henderson , qemu-devel@nongnu.org References: <20200924012453.659757-1-richard.henderson@linaro.org> <20200924012453.659757-7-richard.henderson@linaro.org> <7045a238-b702-0031-735a-caa6d726e160@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/25 02:48:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.214, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.bennee@linaro.org, bharata@linux.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 24.09.20 15:30, Richard Henderson wrote: > On 9/24/20 12:56 AM, David Hildenbrand wrote: >> I do wonder if a type for Int256 would make sense - instead of > manually passing these arrays. > > I could do that. It does name better, I suppose, in passing. So long as > you're happy having the guts of the type be public, and not wrapping everything > like we do for Int128... We can do that once we have hardware+compiler support for 256bit ;) > > Either is better than the softfloat style, which would pass 12 arguments to > these helpers... ;-) Indeed > >>> +static void shortShift256Left(uint64_t p[4], unsigned count) >>> +{ >>> + int negcount = -count & 63; >> >> That's the same as "64 - count", right? (which I find easier to get) > > In this case, yes. > > Of course, more hosts have a "neg" instruction than they do a > "subtract-from-immediate" instruction. When the shift instruction only > examines the low N bits, the "& 63" is optimized away, so this can result in 1 > fewer instruction in the end. > > Which is why I almost always use this form, and it's already all over the code > inherited from upstream. > >> Wow, that's a beast :) > > But not much worse than muladd_floats(), I'm pleased to say. Definitely! -- Thanks, David / dhildenb