Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site gitpyr.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!gatech!gitpyr!robert From: robert@gitpyr.UUCP (Robert Viduya) Newsgroups: net.micro.att Subject: Re: What's wrong with this program (3b2)? Message-ID: <493@gitpyr.UUCP> Date: Tue, 25-Jun-85 03:08:00 EDT Article-I.D.: gitpyr.493 Posted: Tue Jun 25 03:08:00 1985 Date-Received: Wed, 26-Jun-85 06:25:10 EDT References: <104@gwsd.UUCP> <476@gitpyr.UUCP> <339@cuae2.UUCP> <199@hadron.UUCP> Organization: Georgia Tech, Atlanta Lines: 36 > > I think a major point is, if the 3B2 n e e d s the '-f' flag, it > should automagically be included at compile time. We did this for > PDP-11's without floating point: there was a compile-time option > (when compiling the C compiler!) to determine whether -f was a > compiler option or requirement. (We == the UNIX community; > reference == V5/V6 ff -- pre-COFF days.) > > Joe Yao hadron!jsdy@seismo.{ARPA,UUCP} I disagree with this, since using the -f increases the size of the program, *regardless* of whether you use floating point numbers in the program or not. I was doing some futzing around earlier this evening with the 3B2 and discovered that a (non-floating point) program compiled with -f can sometimes be up to 10K larger than it would be compiled without (I used ls(1) to get my numbers, not size(1)). From what I understand, floating point simulation is done by trapping the "illegal instructions" as the program executes and calling a subroutine to handle the instruction. The assembler does not generate calls to the floating point subroutines. This means that the loader cannot tell if the floating point library is needed or not (unless it examines each instruction, looking for a floating point one) and because of that it will always load in the floating point library if the -f option was given. I've heard rumors that AT&T is coming out with, or already sells, a new 3B2 with the WE32100 (did I get that number right?) processor which *does* support hardware floating point. robert -- Robert Viduya 01111000 Georgia Institute of Technology ...!{akgua,allegra,amd,hplabs,ihnp4,masscomp,ut-ngp}!gatech!gitpyr!robert ...!{rlgvax,sb1,uf-cgrl,unmvax,ut-sally}!gatech!gitpyr!robert