From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44750) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpls5-0004xU-Al for qemu-devel@nongnu.org; Thu, 29 Sep 2016 20:40:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpls3-0007Pg-Vw for qemu-devel@nongnu.org; Thu, 29 Sep 2016 20:40:13 -0400 Date: Fri, 30 Sep 2016 10:39:57 +1000 From: David Gibson Message-ID: <20160930003957.GO30519@umbus.fritz.box> References: <34249C6D-327A-4ED4-BB2D-8E2F532A5720@gmail.com> <7e2274fa-f649-887c-c78e-7f5b09749450@redhat.com> <73DBF468-DE5E-4EF0-A54E-91AD38C74C1D@gmail.com> <20160929041750.GN8390@umbus.fritz.box> <06358F28-FC0A-4BA7-82C4-61A059EDF42E@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bAr+fMtvBxbbbkvl" Content-Disposition: inline In-Reply-To: <06358F28-FC0A-4BA7-82C4-61A059EDF42E@gmail.com> Subject: Re: [Qemu-devel] [Qemu-ppc] How to add my implementation of the fmadds instruction to QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Programmingkid Cc: Peter Maydell , "list@suse.de:PowerPC list:PowerPC" , Eric Blake , qemu-devel qemu-devel --bAr+fMtvBxbbbkvl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 29, 2016 at 12:55:23PM -0400, Programmingkid wrote: >=20 > On Sep 29, 2016, at 11:41 AM, Peter Maydell wrote: >=20 > > On 28 September 2016 at 21:17, David Gibson wrote: > >> I think there is a way you could get both speed and accuracy, but it's > >> a huge project: > >>=20 > >> You'd need to add full float awareness to TCG - so floating point TCG > >> values and floating point operations as tcp micro-ops, defined > >> according to IEEE semantics. Then you'd need to rewrite the TCG > >> frontends in terms of those new ops, at least for target CPUs close > >> enough to IEEE semantics for that to work. And you'd need to rewrite > >> the TCG backends to implement those fp ops in terms of host cpu fp > >> instructions .. at least when the host has fp behaviour close enough > >> to IEEE to make that work, with a fallback to soft float when that's > >> not the case. > >=20 > > Also even if you have float support in both frontend and backend > > you still need to fall back to fully-emulated for the runtime > > corner cases (like where tininess before/after rounding makes a > > difference or where you need to care about minutiae of the > > floating point exception flags, etc). It's not impossible > > but it is a very large amount of technically complicated work. >=20 >=20 > This project sounds like it should have its own web page. Maybe even > its own Google Summer of Code entry. I created a mindmap of > this project. The picture is attached to this email. This is > just a start. Please let me know what should be added or changed. TBH, I think this is rather bigger than a GSoC project. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --bAr+fMtvBxbbbkvl Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJX7bRNAAoJEGw4ysog2bOSXcEQAINJp3vRerVLNMlQjOwYtb0x POGik38bFUxPi4B4p/W5idg2zY/zs5SldMdN2A9XD/jEW2a0FWnwOa1H/GqOsqdG DQODoTGMID7wIumnAMy5jMzzF1sLxXQv76613I7zZ4hLLog3zzFDoFhKhn0I7Bx8 GiMBw+Fz99liZCV+Z45dcsyvJIiNKW9rctQIUQaQheLTtst1yE7t5lpPJavmRLJ8 FY0epeGu9MqhUl0MBxv8kcTXXzjKqeKWJoY5sOCDQnLrXRl9QaP9+TztmYh46QsJ ro+acg4QxEc4MhuwdU4wQQpxBDNIn5cpDncAGzQ6IRV8FVFHCTe3W6GGva7MN6bi n5BLsPnDxoBhFwacFcQfsNrs3oYDr7oMY0LuSD/gfGCdDMpDrtvDXyV9Jm6yuFKA Qz+P8QCR73wM8skPwIoKmQE6o8uh0XWBsCK5J4fG8YPZApQNns4rdvPHvg1rGJ2m S0AKtg9gtd29RQhW5j3Y6rIbwWk+yDspwTR+A7xBv335ju2S2N3O6hAhDPrN1A9D F62b3HQa75EuzGZ3lBnw9VXfCF7PLPphKuwsUyVfilDnqtIz69e2Vndcdss2DR8S x/EbV2mQwZQxayyGxJaheWwr9gJXCE+uyobmCgo2rNxsA1nnlfd3msmTw0AiLJ3h U6SjGhoY2J9Sb/btTKvk =97O3 -----END PGP SIGNATURE----- --bAr+fMtvBxbbbkvl--