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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 D96E2C433B4 for ; Tue, 11 May 2021 16:02:01 +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 7B2D9611CA for ; Tue, 11 May 2021 16:02:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B2D9611CA 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]:46012 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lgUpc-0006dK-8C for qemu-devel@archiver.kernel.org; Tue, 11 May 2021 12:02:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38960) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgUlG-0001fa-TY for qemu-devel@nongnu.org; Tue, 11 May 2021 11:57:32 -0400 Received: from mail-ej1-x629.google.com ([2a00:1450:4864:20::629]:36421) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lgUlA-0002zo-B7 for qemu-devel@nongnu.org; Tue, 11 May 2021 11:57:30 -0400 Received: by mail-ej1-x629.google.com with SMTP id j10so3465815ejb.3 for ; Tue, 11 May 2021 08:57:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=p2rJ0zoo8G2DJw8BhlBTljLEehJKUUHaIUJln9zB0Oo=; b=tVKLeLOjIAbNuYC/UKdFt7maKQ4YbwfrXH0ONNBPE4TAFPuAa7lYdEU6AYqCSzzn6y 2qqj+/N77mHQAxFBLA2ngqgvq8F0tc/UsYtQZm1WT5t+aB1cerUptwTjjHMAUb5GbJcn ezpeHLkIRZFaXHl74f4/DE/eRe0EJweC5j+mEbnd7xEzzdcbeOUv8KwSE+pS+mcnPLes AyGfpI38uoJ5czZqulsV88dankQ85kbISVyJoO37Xgjb00GsK9tNgUnsIHmDBozDEBus uVQidaVzoBG5LFYuVVVYqnXAZ38fTn1ICwzH8gceEs+Z2bt4VoA9BOb+JFYIpc6B/5ny 02yw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=p2rJ0zoo8G2DJw8BhlBTljLEehJKUUHaIUJln9zB0Oo=; b=UYQNQTXMIcqW9MyI+occnfLn17PMpepqNccaCb8io0KxmJJSpSGfCdLiJppCR3IRwN nFlpamRxWta4L+gbVN94t2yt1nxC5VcnntmgSqealx6oDkf6Zdc00eiip5c70RFqZzsm NqZEVXC+2Q67cmjzV0+HXC6T1cBAh9B9FluCe8VIReXI3oJCQfm1qe3PfhcTGbpDlBNq YAZvHJEzA3km0sV9Mt6V+T+0Q6LPqlLs4VhD9iG8F9D0CPbJtjBP6emAgkyUB1aFVkSa yWLwRYNIQqvyDbIOEkcAXZ+9CY2DXGORiYLVcPy9TlP8VUuxxIgbHxKAVvSWKRjKpcXr 1NNw== X-Gm-Message-State: AOAM532IjCdt5CyOWR7WimeutONdRzznRGgjQwkD7qIaxp3809XlfJa0 FnKzzWf9Cl48/nPbMYgYIDp3ayBDCKgFyNMkRH6BYg== X-Google-Smtp-Source: ABdhPJy3vNoc72bYTM8vQe2RIOu9qAQu5KZHlMJLRI138bZf29PDBqqumLPRGdGPHRK84oipKNPcPR/YEf6a0j7TLwE= X-Received: by 2002:a17:906:b1cc:: with SMTP id bv12mr32174913ejb.407.1620748642233; Tue, 11 May 2021 08:57:22 -0700 (PDT) MIME-Version: 1.0 References: <20210430202610.1136687-1-richard.henderson@linaro.org> <20210430202610.1136687-7-richard.henderson@linaro.org> In-Reply-To: From: Peter Maydell Date: Tue, 11 May 2021 16:56:09 +0100 Message-ID: Subject: Re: [PATCH v6 06/82] target/arm: Implement SVE2 saturating/rounding bitwise shift left (predicated) To: Richard Henderson Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2a00:1450:4864:20::629; envelope-from=peter.maydell@linaro.org; helo=mail-ej1-x629.google.com 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, RCVD_IN_DNSWL_NONE=-0.0001, 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: qemu-arm , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 11 May 2021 at 16:40, Richard Henderson wrote: > > On 5/11/21 3:43 AM, Peter Maydell wrote: > >> +#define do_sqshl_d(n, m) \ > >> + ({ uint32_t discard; do_sqrshl_d(n, m, false, &discard); }) > > Why pass in &discard rather than just NULL ? (Similarly below.) > > sat != NULL means enable saturation. > > Discard the results because unlike NEON, there is no architectural SVE flag to > indicate that saturation has occurred. Aha. Might be useful to expand the comment a little: /* * Unlike the NEON and AdvSIMD versions, there is no QC bit to set. * We pass in a pointer to a dummy saturation field to trigger * the saturating arithmetic but discard the information about * whether it has occurred. */ -- PMM