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=-5.1 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 C9587C4361B for ; Wed, 16 Dec 2020 14:46:50 +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 47D00233CF for ; Wed, 16 Dec 2020 14:46:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47D00233CF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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bh=Hjm/kA/sFZcms4+61kGKjeRy8wiBSmgtr1BZ+9qS3V8=; b=KaZ79IbiVzZyerW+SXlProhvJOpweO4nXuV6GLdVChFoQEuVjMGcitzqkYSAynZzoK7DTs tRbadECob3HoGqnbPecMkeDxdY1hhlGnVlxSUM3hlamtHwPV/v+gE3ef573/5cSxa9YF6W o/v+RAye0rcTfC/42h0Quk8vLXgOwAk= 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-208-3ata3QCUNpCqV3tKm6cMuw-1; Wed, 16 Dec 2020 09:44:35 -0500 X-MC-Unique: 3ata3QCUNpCqV3tKm6cMuw-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 8CF04107AD4B; Wed, 16 Dec 2020 14:44:33 +0000 (UTC) Received: from [10.36.115.49] (ovpn-115-49.ams2.redhat.com [10.36.115.49]) by smtp.corp.redhat.com (Postfix) with ESMTP id A8E9960CCC; Wed, 16 Dec 2020 14:44:32 +0000 (UTC) Subject: Re: [PATCH v3 0/4] target/s390x: Improve carry computation To: Richard Henderson , qemu-devel@nongnu.org References: <20201214221356.68039-1-richard.henderson@linaro.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Wed, 16 Dec 2020 15:44:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201214221356.68039-1-richard.henderson@linaro.org> 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=63.128.21.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.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, DKIMWL_WL_HIGH=-0.001, 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, RCVD_IN_MSPIKE_H4=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: Thomas Huth , Cornelia Huck Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 14.12.20 23:13, Richard Henderson wrote: > While testing the float128_muladd changes for s390x host, > emulating under x86_64 of course, I noticed that the code > we generate for strings of ALCGR and SLBGR is pretty awful. > > I realized that we were missing a trick: the output cc is > based only on the output (result and carry) and so we don't > need to save the inputs. And once we do that, we can use > the output carry as a direct input to the next insn. > LGTM, @Conny, can you pick these? -- Thanks, David / dhildenb