From owner-cvs-src@FreeBSD.ORG Mon May 5 16:30:47 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DD2E937B404; Mon, 5 May 2003 16:30:47 -0700 (PDT) Received: from canning.wemm.org (canning.wemm.org [192.203.228.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id D582943F93; Mon, 5 May 2003 16:30:46 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by canning.wemm.org (Postfix) with ESMTP id AE7F82A8AE; Mon, 5 May 2003 16:30:46 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Bruce Evans In-Reply-To: <20030502030109.B20181@gamplex.bde.org> Date: Mon, 05 May 2003 16:30:46 -0700 From: Peter Wemm Message-Id: <20030505233046.AE7F82A8AE@canning.wemm.org> cc: cvs-src@FreeBSD.org cc: Maxim Sobolev cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: David O'Brien Subject: Re: cvs commit: src/lib/libc/amd64/gen fabs.S modf.S X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 May 2003 23:30:48 -0000 Bruce Evans wrote: > On Thu, 1 May 2003, David O'Brien wrote: > > > On Thu, May 01, 2003 at 02:24:23AM +0300, Maxim Sobolev wrote: > > > Does this mean that it is theoretically possible to use those > > > and other similar functions on SSE2-capable ia32 processors, such > > > as p4, instead of x87 FPU ones? > > > > Probably. You'll have to do a little /%r/%e/ action. > > Not to mention changing the i386 calling convention. But you wouldn't > want to use these and other similar functions on SSEn-capable ia32 > processors, since they don't use SSEn except for using SSE1 registers > to pessimize the function call protocol a little for at least the > callee (the callee has to do extra work to move values from wrong > registers via the stack). Perhaps other unsimilar functions get > more benefits from SSE. > > BTW, is it really safe to use negative stack offsets for scratch > variables ? Where is the signal stack? fabs() and some other functions > use negative stack offsets, but modf() uses a normal frame pointer. Yes. There is a 128 byte 'red zone' below the stack pointer that may be used by leaf functions. Signals delivery is supposed to skip that space, but I haven't done that yet. 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