From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54616) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VJ4dK-000144-EX for qemu-devel@nongnu.org; Mon, 09 Sep 2013 12:48:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VJ4dF-0005FH-MA for qemu-devel@nongnu.org; Mon, 09 Sep 2013 12:48:14 -0400 Date: Mon, 9 Sep 2013 18:47:51 +0200 From: Aurelien Jarno Message-ID: <20130909164750.GA32430@ohm.aurel32.net> References: <1378327754-8415-1-git-send-email-sw@weilnetz.de> <52279D6A.6040302@weilnetz.de> <20130909145302.GB4966@ohm.aurel32.net> <522DF3EA.6060606@weilnetz.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <522DF3EA.6060606@weilnetz.de> Subject: Re: [Qemu-devel] [PATCH] tci: Add implementation of rotl_i64, rotr_i64 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Weil Cc: Richard Henderson , qemu-stable@nongnu.org, qemu-devel On Mon, Sep 09, 2013 at 06:14:34PM +0200, Stefan Weil wrote: > Am 09.09.2013 16:53, schrieb Aurelien Jarno: > > On Wed, Sep 04, 2013 at 10:51:54PM +0200, Stefan Weil wrote: > >> Am 04.09.2013 22:49, schrieb Stefan Weil: > >>> It is used by qemu-ppc64 when running Debian's busybox-static. > >>> > >>> Signed-off-by: Stefan Weil > >>> --- > >>> > >>> This patch is also useful for QEMU 1.6. > >> ... so I should have added qemu-stable. Done now. > >> > > Why is it needed for qemu-stable? It should only improve performance, as > > these two ops are not mandatory ops. In general I don't think we should > > have performance improvements in a stable minor release (unless of course > > it's a big regression from previous). > > Hi Aurelien, > > tci has always set TCG_TARGET_HAS_rot_i64, and target-ppc64 uses the > rotl_i64 and rotr_i64 TCG opcodes. > > The old implementation just triggered a TODO assertion. That's how I > implemented TCI: I started with TODO assertions for all opcodes and > replaced them by real code as soon as I got a test case which used them. > Now I have a test case :-) Ok, so it might be a good idea to review the remaining non-implemented optional ops and to disable them to avoid that in the future. > => It's not a performance issue, but fixes a fatal assertion. > => It should be used in 1.6. > It should probably also be used in older versions, as rotl and rotr have been used by various targets for a few years (at least since version 0.10.0, probably even before). -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net