From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 5A86A13832E for ; Fri, 19 Aug 2016 18:02:59 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id C6BE7E0B86; Fri, 19 Aug 2016 18:02:46 +0000 (UTC) Received: from omr-a013e.mx.aol.com (omr-a013e.mx.aol.com [204.29.186.60]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id D9544E0B7E for ; Fri, 19 Aug 2016 18:02:45 +0000 (UTC) Received: from mtaout-aad01.mx.aol.com (mtaout-aad01.mx.aol.com [172.26.127.225]) by omr-a013e.mx.aol.com (Outbound Mail Relay) with ESMTP id 8F04538000A8 for ; Fri, 19 Aug 2016 14:02:44 -0400 (EDT) Received: from [192.168.1.52] (0x5b3139322e3136382e312e35325d [71.122.242.106]) by mtaout-aad01.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id A8ED63800009A; Fri, 19 Aug 2016 14:02:43 -0400 (EDT) Subject: Re: [gentoo-dev] New project: LLVM To: gentoo-dev@lists.gentoo.org References: <20160816182204.61c27681.mgorny@gentoo.org> <20160819020737.5419083.98443.119986@pathscale.com> <36efd7a3-ce51-43ed-8aef-e1d6d79a4e5d@gentoo.org> From: james Message-ID: <1b9f33d3-3807-bf55-f021-3ecfb0654c7d@verizon.net> Date: Fri, 19 Aug 2016 14:02:43 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit x-aol-global-disposition: G x-aol-sid: 3039ac1a7fe157b749c3558d X-AOL-IP: 71.122.242.106 X-Archives-Salt: 938199f5-226b-434a-9dbe-c50fd15a41f4 X-Archives-Hash: 057882b8f0150f7626009f56f9a799af On 08/19/2016 11:15 AM, C Bergström wrote: > On Fri, Aug 19, 2016 at 11:01 PM, Luca Barbato wrote: >> BTW is pathscale ready to be used as system compiler as well? > > I wish, but no. We have known issues when building grub2, glibc and > the Linux kernel at the very least. Someone* did report a long time > ago that with their unofficial port, were able to build/boot the > NetBSD kernel. > (*A community dev we trusted with our sources and was helping us with > portability across platforms) > > The stuff with grub2 may potentially be fixed in the "near" future... > the others are more tricky. In general if clang can do it, we have a > strong chance as well. > > As a philosophy - "we" aren't really trying to be the best generic > compiler in the world. We aim more on optimizing as much for known > targets. So if by system you mean, a compiler that would produce an > "OS" which only runs on a single class of hardware, then yeah it could > work at some point in the future. Specifically, on x86 we default on > host CPU optimizations. So on newer Intel hardware it's easy to get a > binary that won't run on AMD or older 64bit Intel. > > More recently on ARMv8 - we turn on processor specific tuning. So > while it may "run", the difference between APM's mustang and Cavium > ThunderX is pretty big and running binaries intended for A and ran on > B would certainly take a hit.. (this is just the tip of the iceberg) > > For general scalar OS code it isn't likely to matter... the real > impact being like 1-10% difference (being very general.. it could be > less or more in the real world..) > > For HPC codes or anything where you get loops or computationally > complex - the gloves are off and I could see big differences... (again > being general and maybe a bit dramatic for fun) OK (actually fantastic!). Looking at the pathscale site pages and github, perhaps a cheap arm embedded board where llvm is the centerpiece of compiling a minimal system to entice gentoo-llvm testers, would be possible in the near future?. I have a 96boards, HiKey arm64v8 that I could dedicate to gentoo+armv8-llvm testing, if that'd help. [1] Perhaps a baseline bootstrap iso (or such) version targeted at llvm-centric testers on x86-64 or armv8 ? Skip grub2 and use grub-legacy or lilo or (?), since there seems to be issues with llvm-grub2. [1] http://dev.gentoo.org/~tgall/ No matter how you slice it, from someone who is focused on building minimized and embedded (bare metal) systems that are customized and coalesced into a heterogeneous gentoo cluster for HPC, this is wonderful news. Finally a vendor in the cluster space, with some vision and common-sense, imho. Heterogeneous and open HPC is where is at, imho. If there is a forum where the community and pathscale folks discuss issues, point that out as I could not find one for deeper reading.... hth, James