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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 5F803C433E0 for ; Thu, 9 Jul 2020 17:39:50 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 164622078B for ; Thu, 9 Jul 2020 17:39:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 164622078B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4B2k2W5gKKzDrC0 for ; Fri, 10 Jul 2020 03:39:47 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4B2jzg0StczDqxk for ; Fri, 10 Jul 2020 03:37:18 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 069HbDTo006123; Thu, 9 Jul 2020 12:37:13 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 069HbCBu006122; Thu, 9 Jul 2020 12:37:12 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Thu, 9 Jul 2020 12:37:12 -0500 From: Segher Boessenkool To: Mathieu Desnoyers Subject: Re: Failure to build librseq on ppc Message-ID: <20200709173712.GL3598@gate.crashing.org> References: <972420887.755.1594149430308.JavaMail.zimbra@efficios.com> <20200708005922.GW3598@gate.crashing.org> <87k0ze2nv4.fsf@mpe.ellerman.id.au> <20200708235331.GA3598@gate.crashing.org> <1968953502.5815.1594252883512.JavaMail.zimbra@efficios.com> <20200709001837.GD3598@gate.crashing.org> <1769596686.6365.1594302227962.JavaMail.zimbra@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1769596686.6365.1594302227962.JavaMail.zimbra@efficios.com> User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Boqun Feng , linuxppc-dev , Michael Jeanson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jul 09, 2020 at 09:43:47AM -0400, Mathieu Desnoyers wrote: > > What protects r17 *after* this asm statement? > > As discussed in the other leg of the thread (with the code example), > r17 is in the clobber list of all asm statements using this macro, and > is used as a temporary register within each inline asm. That works fine then, for a testcase. Using r17 is not a great idea for performance (it increases the active register footprint, and causes more registers to be saved in the prologue of the functions, esp. on older compilers), and it is easier to just let the compiler choose a good register to use. But maybe you want to see r17 in the generated testcases, as eyecatcher or something, dunno :-) Segher