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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EA617C43334 for ; Fri, 10 Jun 2022 14:08:30 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LKN992lSKz3fDv for ; Sat, 11 Jun 2022 00:08:29 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4LKN8g6rmDz2yjS for ; Sat, 11 Jun 2022 00:08:02 +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 25AE5n6C008179; Fri, 10 Jun 2022 09:05:49 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 25AE5nmO008178; Fri, 10 Jun 2022 09:05:49 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 10 Jun 2022 09:05:48 -0500 From: Segher Boessenkool To: Rohan McLure Subject: Re: [PATCH 1/6] powerpc: Add ZERO_GPRS macros for register clears Message-ID: <20220610140548.GQ25951@gate.crashing.org> References: <20220601054850.250287-1-rmclure@linux.ibm.com> <20220601160023.GV25951@gate.crashing.org> <88BD925A-D6A8-4983-A573-7D9CEE51CDE7@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <88BD925A-D6A8-4983-A573-7D9CEE51CDE7@linux.ibm.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: linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi! On Fri, Jun 10, 2022 at 01:32:58PM +1000, Rohan McLure wrote: > > On 2 Jun 2022, at 2:00 am, Segher Boessenkool wrote: > > This is for unary operations, not binary operations (there is only one > > item on the RHS). You can in principle put a string "a,b" in the rhs > > parameter, but in practice you need a or b to depend on the loop counter > > as well, so even such trickiness won't do. Make the naming less > > confusing, maybe? Or don't have an unused extra level of abstraction in > > the first place :-) > Yep I see how having a macro to perform rX = rX <> Y for arbitrary infix <> and operand > is unlikely to find much use outside of ZERO_GPRS. Aha. On PowerPC (like on most RISC-like architectures) all the normal instructions are rD := rA OP rB, not rD := rD OP rA. It looks like that is our disconnect :-) Segher