From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46689) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpm4j-0006i7-Po for qemu-devel@nongnu.org; Thu, 29 Sep 2016 20:53:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpm4h-0001pI-Py for qemu-devel@nongnu.org; Thu, 29 Sep 2016 20:53:16 -0400 Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: Programmingkid In-Reply-To: <20160930003957.GO30519@umbus.fritz.box> Date: Thu, 29 Sep 2016 20:44:28 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: 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> <20160930003957.GO30519@umbus.fritz.box> 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: David Gibson Cc: Peter Maydell , "list@suse.de:PowerPC list:PowerPC" , Eric Blake , qemu-devel qemu-devel On Sep 29, 2016, at 8:39 PM, David Gibson wrote: > 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. >=20 > TBH, I think this is rather bigger than a GSoC project. If it is really big, then it should be broken down into easier steps. Any idea what those steps could be?=