From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id B34F039888B2 for ; Fri, 30 Apr 2021 15:30:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org B34F039888B2 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-120-heVctxiuOF6xAi_edQcnbg-1; Fri, 30 Apr 2021 11:30:14 -0400 X-MC-Unique: heVctxiuOF6xAi_edQcnbg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 789BD801AC9; Fri, 30 Apr 2021 15:30:13 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-115-124.ams2.redhat.com [10.36.115.124]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 744CA60C04; Fri, 30 Apr 2021 15:30:12 +0000 (UTC) From: Florian Weimer To: Wilco Dijkstra via Libc-alpha Cc: Szabolcs Nagy , Wilco Dijkstra Subject: Re: [PATCH 0/5] Added optimized memcpy/memmove/memset for A64FX References: <20210430150127.GV9028@arm.com> Date: Fri, 30 Apr 2021 17:30:25 +0200 In-Reply-To: (Wilco Dijkstra via Libc-alpha's message of "Fri, 30 Apr 2021 15:23:09 +0000") Message-ID: <87eeer4woe.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Apr 2021 15:30:17 -0000 * Wilco Dijkstra via Libc-alpha: > Hi Szabolcs, > >>> I meant using an actual NOP in the #else case so that existing string functions >>> won't change. Also note the #defines in the #if and #else need to be indented. >> >> is that really useful? >> 'bti c' is already a nop if it's unsupported. > > Well it doesn't seem to behave like a NOP. So to avoid slowing down > all string functions, bti c must be removed completely, not just from > A64FX memcpy. Using a real NOP is fine in all cases as long as > HAVE_AARCH64_BTI is not defined. I'm probably confused, but: If BTI is active, many more glibc functions will have BTI markers. What makes the string functions special? Thanks, Florian