From owner-cvs-all@FreeBSD.ORG Fri Apr 8 16:47:18 2005 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 A8F5516A4CE; Fri, 8 Apr 2005 16:47:18 +0000 (GMT) Received: from cs.rice.edu (cs.rice.edu [128.42.1.30]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3415643D3F; Fri, 8 Apr 2005 16:47:18 +0000 (GMT) (envelope-from alc@cs.rice.edu) Received: from localhost (calypso.cs.rice.edu [128.42.1.127]) by cs.rice.edu (Postfix) with ESMTP id C234D4A9AE; Fri, 8 Apr 2005 11:47:17 -0500 (CDT) Received: from cs.rice.edu ([128.42.1.30]) by localhost (calypso.cs.rice.edu [128.42.1.127]) (amavisd-new, port 10024) with LMTP id 32074-01-58; Fri, 8 Apr 2005 11:47:17 -0500 (CDT) Received: by cs.rice.edu (Postfix, from userid 19572) id F0F7F4A9A8; Fri, 8 Apr 2005 11:47:16 -0500 (CDT) Date: Fri, 8 Apr 2005 11:47:16 -0500 From: Alan Cox To: Alan Cox , src-committers@FreeBSD.ORG, cvs-src@FreeBSD.ORG, cvs-all@FreeBSD.ORG Message-ID: <20050408164716.GI20275@cs.rice.edu> References: <200504080515.j385FtbX016388@repoman.freebsd.org> <20050408061426.GH20275@cs.rice.edu> <20050408160358.GA37897@VARK.MIT.EDU> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050408160358.GA37897@VARK.MIT.EDU> User-Agent: Mutt/1.4.2i X-Virus-Scanned: by amavis-2.2.1 at cs.rice.edu Subject: Re: cvs commit: src/lib/libc/amd64/string Makefile.inc bcmp.S memcmp.S 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: Fri, 08 Apr 2005 16:47:18 -0000 On Fri, Apr 08, 2005 at 12:03:58PM -0400, David Schultz wrote: > On Fri, Apr 08, 2005, Alan Cox wrote: > > On Fri, Apr 08, 2005 at 05:15:55AM +0000, Alan Cox wrote: > > > alc 2005-04-08 05:15:55 UTC > > > > > > FreeBSD src repository > > > > > > Modified files: > > > lib/libc/amd64/string Makefile.inc > > > Added files: > > > lib/libc/amd64/string bcmp.S memcmp.S > > > Log: > > > Add machine-specific, optimized implementations of bcmp and memcmp. > > > > > > PR: 73111 > > > Submitted by: Ville-Pertti Keinonen (taken from NetBSD) > > > MFC after: 3 weeks > > > > > > Revision Changes Path > > > 1.2 +1 -1 src/lib/libc/amd64/string/Makefile.inc > > > 1.1 +25 -0 src/lib/libc/amd64/string/bcmp.S (new) > > > 1.1 +41 -0 src/lib/libc/amd64/string/memcmp.S (new) > > > > It is worth noting that by default the current version of gcc > > automatically inlines its own implementation of these functions. That > > implementation is slower than this new libc implementation for strings > > of non-trivial length. > > IIRC, gcc only inlines these in special cases, e.g. if it knows > the length or contents of one of the strings. But this may have > changed. Yes, however, for bcmp and memcmp the length is given as a parameter and thus is always known. The surprising fact is that the length does not have to be a constant for inlining to occur. Arguably gcc's heuristic for inlining these functions should require the length to be a small constant. Alan