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Re: GCC floating point usage
- From: Richard Henderson <rth at redhat dot com>
- To: Mark Mitchell <mark at codesourcery dot com>
- Cc: Mike Stump <mrs at apple dot com>, Geoff Keating <geoffk at geoffk dot org>, "steby at enea dot se" <steby at enea dot se>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Wed, 16 Oct 2002 15:27:24 -0700
- Subject: Re: GCC floating point usage
- References: <20021016201445.GC22988@redhat.com> <360570000.1034800416@warlock.codesourcery.com>
On Wed, Oct 16, 2002 at 01:33:36PM -0700, Mark Mitchell wrote:
> >Anything less is asking for trouble.
>
> Yes, programmers have to be very careful not to accidentally let FP
> slip into no-FP tasks.
No, what I mean is that I'm with Geoff: you won't be able to
guarantee that the compiler does the right thing without a
completely different approach.
You're going to need the front/middle-end to indicate whether
"floating point has been used", and if not, hide *all* existance
of the fp registers from the register allocators. Nothing less
gives you assurance they won't be used.
r~