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From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: Floating point problem
Date: 1997/04/01
Message-ID: <1997Apr1.151216.1@eisner>#1/1
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References: <199703271518_MC2-1360-15BE@compuserve.com> <dewar.859526944@merv>
 <1997Mar28.095005.1@eisner> <dewar.859583580@merv> <333E18D8.1F84@bix.com>
 <1997Mar30.113716.1@eisner> <dewar.859869032@merv>
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Organization: LJK Software
Newsgroups: comp.lang.ada
Date: 1997-04-01T00:00:00+00:00
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In article <dewar.859869032@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) writes:

> That seems to be getting a little absurd to me. Larry, do you think the
> compiler should be careful to generate code that detects that it is running
> on an 8080 and aborts if so (it is definitely possible to write such
> discriminating code, in fact you can find it in Intel manuals).

If there is an operating system which will start up the program on
the "wrong" chip, yes.

> Larry if you are really interested in running GNAT on an x86 with no
> floating-point and an OS that does not support fpt, why not investigate
> how to fix the problem, I doubt it is that hard. The reason we don't
> spend any effort on this problem is that we don't really have an interest
> in running GNAT on such platforms!

I have no interest in running the output of Ada compilers on such
platforms either.  My interest, again, is sure-fire detection of
such situations.  Ignoring issues of how much time I have to pursue
a solution for a compiler, I fear the same problem would arise with
the difference between SPARC-2 and SPARC-1 (if there is such a thing)
if compiler developers take the attitude that any issue of machine
incompatibility is to be detected solely by humans reading the box
before purchasing the output of the Ada compiler.

It is certainly the case that operating-system level approaches
would solve this for all compilers, but sometimes one wants to
sell software to those with least-common-denominator taste in
operating systems.

I say "compiler developers" since although this has talked about
GNAT I have not noticed any of the other Ada compiler developers
speaking up to say "our compiler handles that" :-)

Larry Kilgallen