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Re: expand and truncate and 387
>
> In message <Pine.LNX.4.03.9811091738520.15420-100000@moshier.ne.mediaone.net>
> you write:
> >
> > > I don't think the x86 backend worries about rounding and truncation on
> > > fp->fp conversions.
> >
> > Assuming the usual long-double precision control setting,
> > converting from lower to higher precision is a no-op.
> Is that something we can safely assume? I don't think so.
Current implementation of i386.md assumes this. And there is IMO
no way to do another..
>
> So it seems to me that it really is not safe to ignore extensions & truncations
> on the x86, at least it it is not safe to do by default.
We can IMO ignore extensions, since there is no way to do them anyway (it is
not neccesary, since all values are already extended).
Truncations done by writing to memory should be IMO ignored with some switch,
(math is sitll inexact as it is and truncations costs a lot and don't fix
the problem) but it is not so significant now.
Honza
>
> jeff
--
OK. Lets make a signature file.
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| Jan Hubicka (Jan Hubi\v{c}ka in TeX) hubicka@freesoft.cz |
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