From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id E48C9DDDDB for ; Wed, 21 Nov 2007 08:01:21 +1100 (EST) Message-Id: From: Kumar Gala To: Scott Wood In-Reply-To: <20071120175416.GA4389@loki.buserror.net> Content-Type: text/plain; charset=US-ASCII; format=flowed Mime-Version: 1.0 (Apple Message framework v915) Subject: Re: [PATCH] [POWERPC] Emulate isel (Integer Select) instruction Date: Tue, 20 Nov 2007 15:01:11 -0600 References: <20071120175416.GA4389@loki.buserror.net> Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Nov 20, 2007, at 11:54 AM, Scott Wood wrote: > On Mon, Nov 19, 2007 at 09:36:57PM -0600, Kumar Gala wrote: >> isel (Integer Select) is a new user space instruction in the >> PowerISA 2.04 spec. Not all processors implement it so lets emulate >> to ensure code built with isel will run everywhere. > > Given that the instruction is meant to be a performance enhancement, > we should probably warn the first few times it's emulated, so the user > knows they should change their toolchain setup if possible. The same is true of mcrxr, popcntb, and possibly string ld/st. Feel free to submit a patch that warns about their usage. - k