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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 EAD29C433EF for ; Fri, 10 Sep 2021 09:32:35 +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 555046101A for ; Fri, 10 Sep 2021 09:32:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 555046101A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:45932 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mOcte-0006B6-E4 for qemu-devel@archiver.kernel.org; Fri, 10 Sep 2021 05:32:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54892) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mOcsZ-0005HQ-8N for qemu-devel@nongnu.org; Fri, 10 Sep 2021 05:31:28 -0400 Received: from mail-wr1-x42d.google.com ([2a00:1450:4864:20::42d]:36535) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mOcsV-0003Wh-OG for qemu-devel@nongnu.org; Fri, 10 Sep 2021 05:31:27 -0400 Received: by mail-wr1-x42d.google.com with SMTP id g16so1702694wrb.3 for ; Fri, 10 Sep 2021 02:31:22 -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=RpAQ7vNrv0bASmLyuLZvnjH8wlkQv7MQ5QwSC9XkwA4=; b=UOSBZBxMMQ+p1jJPRw60jIJjumaIQmhqU0H7fMXMP3+qRUxs+NebOb5CurflMCI2n9 bZPeBK3X5O0DLEkgMwqEVpkKnZmXZf0jPQc6NkmvMFi0FA6oArLTdQqphhMkGQCmuIYM jn6v+3dsM+KvQPvDSWDzKhtFb3l/2r7kt2vQZWpnUO7nVDIS5o1S5RUxFYGfNa+g/rtD wW2di7IOZkAggjl5JkVyK2NrQTVf2iYI4MulrqVkVTaVeSYIKaQAMNtsQHFMe6JFWjsf 8Vo9C0BPsfNWvTBBtbTsgQkKYoW4M3hXti7jkYTwB8unKybadR/zOmVC2vVuD2eRIcLs h3HA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=RpAQ7vNrv0bASmLyuLZvnjH8wlkQv7MQ5QwSC9XkwA4=; b=jQViW1rbspJ4bSEBgR5hb6urZPE/8zbtVGxU67rTCZmbPKeFGJqb6rJ2K+gVCjWnb6 3JBCQ++CDq7YA+ZWDJ6UTEI0xRM7sj+ktZwB1guuPLuhcLyW58ks35QfeXMGEkl1bLOT fMtaJV6stb+CcblPQ8UlxkXGuJW7w+tDp26fJ2099PJI7PTsbpJJY75VJ5D0lsFclmnk MRHJ+pU0E1PibdqRmUTIA4nA1m2SG7ovcgQlkI504AXNwNnxgyvljssxYlvZytHVTgCb K5mj6n583OIRWY5nxCYvM0o4TEwzpd0K8PN/GTX1Rx1wqsvwJzYZtH/MV3Vh4BUaOsTw 3LTA== X-Gm-Message-State: AOAM531JJWcuvIi7hS1us3Hx+Oh+LWebrR+e1ycTFVSIoPrbWKW+XK0x bk/jt02V1nvNgo19bLf7blGsZ1G7hPjhORNjxJEqmQ== X-Google-Smtp-Source: ABdhPJyrs4JSDKPBR2IwFzsjv6cO8UrwexQEZ3Dy34CgS7SiiboHYRsTu/DFV7i2Nu+b7nDyfOpNOqEWVlSN6UoEu5E= X-Received: by 2002:a5d:4a08:: with SMTP id m8mr8470457wrq.263.1631266281438; Fri, 10 Sep 2021 02:31:21 -0700 (PDT) MIME-Version: 1.0 References: <20210902150910.15748-1-peter.maydell@linaro.org> <20210902150910.15748-2-peter.maydell@linaro.org> <76cd3594-f864-232c-8687-19a1d44ff07e@linaro.org> In-Reply-To: From: Peter Maydell Date: Fri, 10 Sep 2021 10:30:31 +0100 Message-ID: Subject: Re: [PATCH 1/4] target/arm: Add TB flag for "MVE insns not predicated" To: Richard Henderson Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2a00:1450:4864:20::42d; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x42d.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=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-arm , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 10 Sept 2021 at 07:46, Richard Henderson wrote: > > On 9/9/21 3:46 PM, Peter Maydell wrote: > > On Fri, 3 Sept 2021 at 14:58, Richard Henderson > > wrote: > >> I think you need to go ahead and end the TB and resync immediately. > >> Just set dc->base.is_jmp = DISAS_UPDATE_NOCHAIN instead. > > > > Is there a rule for when we should set is_jmp to DISAS_UPDATE_NOCHAIN, > > when we should set it to DISAS_UPDATE_EXIT, and when we should call > > gen_lookup_tb() ? We seem to use all three methods at various points > > for "I changed some CPU state and want to end the TB"... > > UPDATE_EXIT is for when you need to return to the main loop; UPDATE_NOCHAIN merely avoids > goto_tb. Direct use of gen_goto_ptr should be reserved for branches (which I think is > already the case). And what about gen_lookup_tb() ? As far as I can tell the semantics of this are the same as setting is_jmp to DISAS_UPDATE_EXIT: the "set PC to s->base.pc_next" happens immediately rather than being done later in arm_tr_tb_stop(), but I don't think that should make a difference. Or is there a case where it matters? If gen_lookup_tb() and DISAS_UPDATE_EXIT are the same, maybe we should get rid of gen_lookup_tb() entirely ? -- PMM