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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D17F1C433DF for ; Tue, 13 Oct 2020 22:33:33 +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 6603C218AC for ; Tue, 13 Oct 2020 22:33:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="soWFH3Mr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6603C218AC 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]:54794 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kSSrM-0000xh-Au for qemu-devel@archiver.kernel.org; Tue, 13 Oct 2020 18:33:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59920) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kSSpW-0000EO-QW for qemu-devel@nongnu.org; Tue, 13 Oct 2020 18:31:39 -0400 Received: from mail-pf1-x442.google.com ([2607:f8b0:4864:20::442]:40310) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kSSpU-000051-2n for qemu-devel@nongnu.org; Tue, 13 Oct 2020 18:31:37 -0400 Received: by mail-pf1-x442.google.com with SMTP id w21so717205pfc.7 for ; Tue, 13 Oct 2020 15:31:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=Xct8EB2JXJGbJ3zKytAaLNNDCzXsSOE2AkEo2n5lLUc=; b=soWFH3Mr/4mmAuLL6ZtplFJY/h9isZh2f5fqwNZFtrhH+0aQA5paKpn1c+iWBENExf jzuTkHbyg29lHM8GbUS2dTbkh+5iU3wWa7jE4D6pU7IGnY53b3SAW+X2RwSG95PlYLid Oknkd5+9Hj1X2c/XioRVGnHtaZtYBUe7rAzMcev5iyXLjWxJaqXYTqLiFpBpU0351lJU v7yiuimsvPUMBdyCgYS0MFuDxBr+j7bLWATgbR/V6Fiqyn6Zje3zk95NITZoCMXnIwDW /EY74w62f0yq6JuZWw3izEiewJfRwcGbCD18O4+JywzIsOCoiv8i1k23mXC5ugoQgHw5 Jzlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Xct8EB2JXJGbJ3zKytAaLNNDCzXsSOE2AkEo2n5lLUc=; b=g0TSmHr+ZZ9N7i3pZRpmpakTLJrTlsh0jTkrFJfVszP5AfYZdxAk/9lS86M6dSDpIU GNV5T2cLiqi9uYn6faY+Y1qelc0c89RBBXgTUqkb7rrutf++JiVoswN2UGOxL5UpZT8u XUKgpY8qsikolbu8EAnzaHME/BI71JcquBegCvL6j1aLdDrwiEB9Y5QPMk90o7oLYB1r WWw0RgETevYWDRuoZ8eAoZL9v8onjRxdMTkSYHA4QXA8fhdq7q+PcUxqCHLCtrKa9Re/ /awnDa758sbwMUVEODhh+NEK2lHG4I+fb/tCJYYub9ASgeSFX1hJzs229HttokL5b1NX b57g== X-Gm-Message-State: AOAM5320nFGcycMUfor7JCciRecC6dStUlcDRNpBB0hwaQUdVCoN3xvK ijMU9zd8kHsgxdtXoyYfHKSzYpbCA5k9Ig== X-Google-Smtp-Source: ABdhPJyBBbq1caDu2kVOpDIacGYUb29bI34USsu9N25IxM2qH05UvbQCHDEq38dxXcyTy9L4ilBT5Q== X-Received: by 2002:a63:5f97:: with SMTP id t145mr1397852pgb.115.1602628292207; Tue, 13 Oct 2020 15:31:32 -0700 (PDT) Received: from [192.168.1.11] ([71.212.141.89]) by smtp.gmail.com with ESMTPSA id a4sm731440pgl.51.2020.10.13.15.31.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Oct 2020 15:31:31 -0700 (PDT) Subject: Re: [PATCH 07/10] target/arm: Implement v8.1M low-overhead-loop instructions To: Peter Maydell , qemu-arm@nongnu.org, qemu-devel@nongnu.org References: <20201012153746.9996-1-peter.maydell@linaro.org> <20201012153746.9996-8-peter.maydell@linaro.org> From: Richard Henderson Message-ID: Date: Tue, 13 Oct 2020 15:31:29 -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: <20201012153746.9996-8-peter.maydell@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::442; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x442.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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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=-0.001, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/12/20 8:37 AM, Peter Maydell wrote: > + nextlabel = gen_new_label(); > + tcg_gen_brcondi_i32(TCG_COND_NE, cpu_R[a->rn], 0, nextlabel); > + gen_jmp(s, read_pc(s) + a->imm); > + > + gen_set_label(nextlabel); > + tmp = load_reg(s, a->rn); > + store_reg(s, 14, tmp); > + gen_jmp(s, s->base.pc_next); > + return true; Oh, fwiw, with the tcg optimization patches just posted, this branch is better inverted. That way the load of rn can be reused on the non-taken branch path. Maybe sometime I'll try to propagate the data to the taken path, but that automatically requires extra memory allocation, so it'll be difficult to do that without a tcg slowdown. r~