From: "John \(Eljay\) Love-Jensen" <eljay@adobe.com>
To: "Terry Frankcombe" <terry@chem.gu.se>, <gcc-help@gcc.gnu.org>
Subject: RE: Internal representation of double variables - 3.4.6 vs 4.1.0
Date: Sat, 10 Mar 2007 18:37:00 -0000 [thread overview]
Message-ID: <EDC8DDD212FEB34C884CBB0EE8EC2D9103B25B71@namailgen.corp.adobe.com> (raw)
In-Reply-To: <1173467304.5215.19.camel@fkpc167>
Hi Terry,
> Is there any sensible reason that these options seem to buried in processor-specific sections?
My guess is because they are processor-specific options.
> Surely the hardware floating point model varies on more than just the x86 family and friends.
Yes. For example, not all 680x0 machines has a FPU.
> Why isn't there a simple, global option to get a portable floating point model?
Because there are different FPU facilities on different platforms that may have a different, non-portable floating-point model.
> Particularly now that gfortran is becoming more popular!
If the Fortran users express a desire for some Fortran level floating-point compliance to a portable floating-point model, perhaps the maintainer of the gfortran front-end tool-chain driver will add a flag to that effect.
I imagine such a flag would have these guarantees:
+ behind the scenes, specifies the processor-specific option to insure floating-point portability
+ may impose severe performance penalties (one-to-two orders of magnitude) on some platforms
+ may cause the compile to fail if the floating-point constraint cannot be fulfilled (which is probably a good thing)
> Tying the floating point model to a particular hardware feature/instruction set (SSE) seems absolutely absurd to me. It should be abstracted to a much higher level.
It's a trade-off, without a doubt.
Java has a facility that allows strong guarantees on floating-point fidelity. And Mathematica allows very powerful expression of symbolic and mathematical manipulation and expression. And there's always Lisp.
Sincerely,
--Eljay
prev parent reply other threads:[~2007-03-09 19:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <f7bda7fe0703090927s589149c3yeeaf992c3b6c26b5@mail.gmail.com>
2007-03-09 18:00 ` max
2007-03-09 18:33 ` Terry Frankcombe
2007-03-09 18:47 ` Brian Dessent
2007-03-09 18:55 ` Terry Frankcombe
2007-03-09 19:08 ` Brian Dessent
2007-03-09 19:27 ` Terry Frankcombe
2007-03-10 18:37 ` John (Eljay) Love-Jensen [this message]
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