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 5DD3BC4727F for ; Fri, 25 Sep 2020 22:08:19 +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 E02D720759 for ; Fri, 25 Sep 2020 22:08:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="WoBkB9yJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E02D720759 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50884 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLvt3-0002xR-UA for qemu-devel@archiver.kernel.org; Fri, 25 Sep 2020 18:08:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37536) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLvrP-0001u2-Mt for qemu-devel@nongnu.org; Fri, 25 Sep 2020 18:06:35 -0400 Received: from mail-pj1-x1043.google.com ([2607:f8b0:4864:20::1043]:35031) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kLvrN-0007Dm-0v for qemu-devel@nongnu.org; Fri, 25 Sep 2020 18:06:35 -0400 Received: by mail-pj1-x1043.google.com with SMTP id jw11so203097pjb.0 for ; Fri, 25 Sep 2020 15:06:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Gm0hfYjHC+YoNFn4Qc8b8DDBPaPC/MFe4xUHN2MuYVk=; b=WoBkB9yJ97l5zdIAURCPoKBLpjiTOgC62RJuhxhTugYYFTRCZbxZZyvLis+1e5Rv4t bx/SkEqAlN77LCpQRG0hLbgGPmGBB43u8gYJv/Zbzv3MTs5cA+YoVc2fDkGOa3R4+7aI vu18LOP2A0Q+mZ78HVgBjl8Pb+pRJ84JUqT7cFaBx0yFFB9AhtA0aTZ4hbeUp/ZLmRcT J5QML5FcE5hFZvERVo1y2ruckeBj7ZDOO26IeTQGHP8298ObCVdTTPLj+KqYps9/fgjM kHYWo6Nw8VoechE+AJe9olRxKxSDyjHPXmKj04gF4AdhZQ28xkCKCJXndny9Lf5SyFtU YY1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Gm0hfYjHC+YoNFn4Qc8b8DDBPaPC/MFe4xUHN2MuYVk=; b=kR8QGvccTE7lyBnXw5zfy6Eylmdvj7BHVJRR33xBsRBmM3OWuiIJbIF39iHAcHVy76 7Yajif1jo/gSTpfecwSENWu4U/phdBccpdByeUhnpLJG35UjP/z3IRAlbnTA6CU0pyMt 3t3ZSE8h9dPHeJgH7gOpLOwb7CW2fwGcm2651cut2ReccjBr2ooCIyU2BujxmACe7T5k BEWKMH/s3jK0NHpFtbE9OR/QXhrx7c/QVzsHK4uqN6cViJKDEEGObSytG+/ijvm+9NxN FuvbMKBJYORXhtPUdBZPxy16GP4yO/aQzSRH6HE5DhvP1oVD7FtdjmZ0q3kTvnX7Hitp 2TRg== X-Gm-Message-State: AOAM531yqXTdvBA1cLHm0wVVcesrfvBXgEMao+OJYc3c4wFyfLYVymCp VfXgAc5GINOQgDkQkvuAY8TYgw== X-Google-Smtp-Source: ABdhPJwPJrJRC76sHcHVeo1+lNywPDqw3mQIay+5H5pG2HcpUl9PXVFeEIhgRwNW0WhMW2YgybKcDg== X-Received: by 2002:a17:90a:6e45:: with SMTP id s5mr572468pjm.12.1601071591144; Fri, 25 Sep 2020 15:06:31 -0700 (PDT) Received: from [192.168.1.11] ([71.212.141.89]) by smtp.gmail.com with ESMTPSA id p11sm3536211pfq.130.2020.09.25.15.06.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Sep 2020 15:06:30 -0700 (PDT) Subject: Re: [PATCH v1 6/8] s390x/tcg: Implement MULTIPLY SINGLE (MSC, MSGC, MSGRKC, MSRKC) To: David Hildenbrand , qemu-devel@nongnu.org References: <20200922103129.12824-1-david@redhat.com> <20200922103129.12824-7-david@redhat.com> From: Richard Henderson Message-ID: <371cb429-a7e2-819e-a016-08bd7adff54e@linaro.org> Date: Fri, 25 Sep 2020 15:06:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200922103129.12824-7-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1043; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1043.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.238, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: qemu-s390x@nongnu.org, Cornelia Huck , Thomas Huth Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/22/20 3:31 AM, David Hildenbrand wrote: > +static uint32_t cc_calc_muls_32(int64_t res) > +{ > + /* Arithmetic shift with sign extension so we can compare against -1ull. */ > + const uint64_t tmp = res >> 31; > + > + if (!res) { > + return 0; > + } else if (!(!tmp || tmp == -1ull)) { Comparing signed vs unsigned. Use -1 without suffix. > +static uint64_t cc_calc_muls_64(int64_t res_high, uint64_t res_low) > +{ > + const uint8_t tmp = res_low >> 63; > + > + if (!res_high && !res_low) { > + return 0; > + } else if (!(!res_high && !tmp) || !(res_high == -1ull && tmp)) { This simplifies to res_high + tmp != 0. Probably better to keep tmp as uint64_t; otherwise we're likely to have an unnecessary zero-extension from uint8_t to uint64_t. Or, drop 'tmp' altogether and use if (res_high + (res_low >> 63) != 0) Otherwise, looks good. r~