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Re: patch: rs6000 specific
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- To: Geoff Keating <geoffk at redhat dot com>
- Cc: Dale Johannesen <dalej at apple dot com>, <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 4 Dec 2001 23:50:25 +0000 (GMT)
- Subject: Re: patch: rs6000 specific
On 4 Dec 2001, Geoff Keating wrote:
> Dale Johannesen <firstname.lastname@example.org> writes:
> > This adds some additional patterns for multiply-add instructions.
> > Bootstrapped and tested on Darwin. (The !POWERPC variants are
> > included, analogous to what was already there, but I was unable
> > to test them.)
> I think that some of these are cases that should never occur.
> Perhaps the generic code is not canonifing them properly?
> It might be that some of these are not strictly IEEE compliant, in
> which case the generic code should still fold them... but only when
> -ffast-math is specified.
Use of multiply-add - apart from to provide built-in functions for the C99
fma family, which we ought to where machine instructions are available -
should be governed by #pragra STDC FP_CONTRACT (default
implementation-defined), which however we don't yet implement.
Joseph S. Myers