From owner-cvs-all@FreeBSD.ORG Tue Sep 23 09:45:32 2003 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 55EC616A4B3; Tue, 23 Sep 2003 09:45:32 -0700 (PDT) Received: from canning.wemm.org (canning.wemm.org [192.203.228.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id A3EBB43FF9; Tue, 23 Sep 2003 09:45:31 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by canning.wemm.org (Postfix) with ESMTP id 6AC882A8DA; Tue, 23 Sep 2003 09:45:31 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Robert Watson In-Reply-To: Date: Tue, 23 Sep 2003 09:45:31 -0700 From: Peter Wemm Message-Id: <20030923164531.6AC882A8DA@canning.wemm.org> cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/include endian.h X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Sep 2003 16:45:32 -0000 Robert Watson wrote: > > On Mon, 22 Sep 2003, Peter Wemm wrote: > > > Microoptimization to allow the compiler to evaluate ntohl() etc on > > known constants at compile time rather than at run time. We have a numbe r > > of nasty hacks around the place to cache ntohl() of constants (eg: nfs). > > This change allows the compiler to compile-time evaluate ntohl(1) as > > 0x01000000 rather than having to emit assembler code to do it. This > > has other smaller flow-on effects because the compiler can see that > > ntohl(constant) itself has a constant value now and can propagate the > > compile time evaluation. > > So should we now be doing a sweep through the tree to remove instances of > this? I.e.: > > /* > * To avoid byte-swapping the same value over and over again. > */ > igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP); > igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP); > > Etc? It is probably premature to do that just yet (only 2 of 5 or so platforms handled), but that was the kind of "optimization" that prompted this. NFS is also riddled with this. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5