https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85164
--- Comment #8 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org>
---
(In reply to Jakub Jelinek from comment #7)
> (In reply to rsand...@gcc.gnu.org from comment #6)
>
> Thanks for handling this.
>
> > > template<unsigned int N, typename Ca>
> > > inline POLY_BINARY_COEFF (Ca, Ca)
> > > known_alignment (const poly_int_pod<N, Ca> &a)
> > > {
> > > typedef POLY_BINARY_COEFF (Ca, Ca) C;
> > > C r = a.coeffs[0];
> > > for (unsigned int i = 1; i < N; ++i)
> > > r |= a.coeffs[i];
> > > return r & -r;
> > > }
> > >
> > > The poly_int* stuff makes this much harder to fix, it is unclear if there
> > > is
> > > some way to get the unsigned type for the C type and use that as r &
> > > -(Cuns)
> > > r;
> > > to avoid the UB, and there is no poly_uint_rtx_p or something to request
> > > poly_uint64 from the rtx. Richard?
> >
> > Changing:
> >
> > (unsigned HOST_WIDE_INT) known_alignment (const_op0)
> >
> > to:
> >
> > known_alignment (poly_uint64 (const_op0))
> >
> > should work.
>
> That will handle this specific case, I was just hoping that for
> known_alignment we could fix all the cases that could be called on
> poly_int64. For HOST_WIDE_INT_MIN, do we want known_alignment to return
> HOST_WIDE_INT_MIN or something different? It is maximum alignment
> admittedly only if we are treating the result as unsigned. Or shall we in
> known_alignment assert or compile time assert that it is unsigned and fix
> all the users?
A compile-time assert sounds good. Will try that on top to see how
invasive it ends up being. (Shouldn't be too bad, since there aren't
many callers.)
