[Libre-soc-dev] All div pipe tests pass

[Jacob Lifshay]

On Wed, Oct 7, 2020, 14:38 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
wrote:

> On 10/7/20, Jacob Lifshay <programmerjake at gmail.com> wrote:
>
> > How about instead making a function `undef` that can be used as follows:
> >
> > def undef(v):
> >     """returns a value that is undefined according to the spec, but the
> > hardware returns `v`."""
> >     return v
>
> > that allows saying that part of the result should be undefined while
> still
> > specifying the value our tests should match (which is not always zero).
>
> do you have / know of examples / cases / instructions where
> undefined==0 is not true?
>

modsw has some: the top 32-bits of the result are undefined and power9
sign-extends the lower 32-bits

there are a whole pile in the mul* instructions.