Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261188AbTIKJl4 (ORCPT ); Thu, 11 Sep 2003 05:41:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261195AbTIKJlz (ORCPT ); Thu, 11 Sep 2003 05:41:55 -0400 Received: from 168.imtp.Ilyichevsk.Odessa.UA ([195.66.192.168]:60944 "HELO 127.0.0.1") by vger.kernel.org with SMTP id S261188AbTIKJlw (ORCPT ); Thu, 11 Sep 2003 05:41:52 -0400 Content-Type: text/plain; charset=US-ASCII From: insecure Reply-To: insecure@mail.od.ua To: Jamie Lokier , "Eric W. Biederman" Subject: Re: nasm over gas? Date: Wed, 10 Sep 2003 00:37:59 +0300 X-Mailer: KMail [version 1.4] Cc: Michael Frank , Yann Droneaud , fruhwirth clemens , linux-kernel@vger.kernel.org, =?iso-8859-1?q?J=F6rn=20Engel?= References: <20030904104245.GA1823@leto2.endorphin.org> <20030907193030.GA21936@mail.jlokier.co.uk> In-Reply-To: <20030907193030.GA21936@mail.jlokier.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <200309100037.59953.insecure@mail.od.ua> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1360 Lines: 31 On Sunday 07 September 2003 22:30, Jamie Lokier wrote: > Eric W. Biederman wrote: > > Actually it is no as simple as that. With the instruction that uses > > %edi following immediately after the instruction that populates it you > > cannot execute those two instructions in parallel. So the code may be > > slower. The exact rules depend on the architecture of the cpu. > > I remember inserting a "nop" into a loop and it went significantly > faster on a Pentium Pro :) My example in _not_ a loop, far from it. That's the point. GCC thinks everything is a loop. > > If you concentrate on those handful of places where you need to > > optimize that is reasonable. Beyond that there simply are not the > > developer resources to do good assembly. And things like algorithmic > > transformations in assembly are an absolute nightmare. Where they are > > quite simple in C. > > If we had enough developer resources to write the whole thing in good > assembly, then for _sure_ we'd have enough to write a perfect compiler! Peace, Jamie. I do _not_ advocate using asm anywhere except speed critical code. -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/