Re: [patch] Fix PR tree-optimization/46049 and tree-optimization/46052

[Richard Guenther <rguenther at suse dot de>]

On Tue, 19 Oct 2010, Ira Rosen wrote:

> 
> 
> Richard Guenther <rguenther@suse.de> wrote on 18/10/2010 12:48:15 PM:
> 
> >
> > Hm, but then this is a problem of the caller, and likely non-SLP mode
> > has the same issue (looking at vectorizable_operation I don't see
> > any special casing handling it for non-SLP, it'll just call
> > vect_get_vec_defs and then vect_get_vec_def_for_operand).
> 
> vect_get_vec_def_for_operand actually treats constants and invariants
> differently, using number of units of the stmt's vectype for constants and
> the type of the operand for invariants.

Well, as far as I can see vect_is_simple_use will assign the operands
defining statement definition to *def (which will be always op itself).
So,

    case vect_constant_def:
      {
        vector_type = get_vectype_for_scalar_type (TREE_TYPE (op));

and

    case vect_external_def:
      {
        vector_type = get_vectype_for_scalar_type (TREE_TYPE (def));

are the same.

> > I think that vectorizable_operation has to special case shifts
> > (it already does for the vectorization test but not for code generation),
> > which also means that it really asks for being separated out
> > into a vectorizable_shift function ...
> >
> > Basically the
> >
> >           if (op_type == binary_op && scalar_shift_arg)
> >             {
> >
> > case should also handle the variant where we need to extend
> > the scalar shift arg to a vector.
> 
> But scalar_shift_arg indicates whether the shift argument is a scalar or a
> vector. How can we treat it as "we need to extend the scalar shift arg to a
> vector" as well?

If the target doesn't support a non-vector shift amount then we always
need to promote it to a vector (and we know how many elements that
will have from the other operands element count).

> vectorizable_shift sounds good to me, I hope there are no other operations
> like that, allowing operands of different types.

I don't think so.

Thanks,
Richard.

> Thanks,
> Ira
> 
> >
> > Richard.
> >
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
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