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Re: patch: rs6000 specific


On 4 Dec 2001, Geoff Keating wrote:

> Dale Johannesen <dalej@apple.com> 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
jsm28@cam.ac.uk


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