On Mon, 2 Aug 2021, Richard Sandiford wrote:
> Richard Biener <rguent...@suse.de> writes:
> > On Fri, 30 Jul 2021, Richard Sandiford wrote:
> >> > @@ -9456,6 +9499,51 @@ vectorizable_load (vec_info *vinfo,
> >> > data_ref = NULL_TREE;
> >> > break;
> >> > }
> >> > + else if (memory_access_type == VMAT_GATHER_SCATTER)
> >> > + {
> >> > + /* Emulated gather-scatter. */
> >> > + gcc_assert (!final_mask);
> >>
> >> For this to be safe, we need to make sure that
> >> check_load_store_for_partial_vectors clears
> >> LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P. Is that already guaranteed?
> >> (Maybe yes, I didn't look closely. :-))
> >
> > I've made sure to fail earlier:
> >
> > @@ -8692,6 +8725,15 @@ vectorizable_load (vec_info *vinfo,
> > "unsupported access type for masked
> > load.\n");
> > return false;
> > }
> > + else if (memory_access_type == VMAT_GATHER_SCATTER
> > + && gs_info.ifn == IFN_LAST
> > + && !gs_info.decl)
> > + {
> > + if (dump_enabled_p ())
> > + dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> > + "unsupported masked emulated gather.\n");
> > + return false;
> > + }
> > }
> >
> > at least I don't see a way to emulate masked gathers ;)
>
> Yeah, that handles masked loads created by ifcvt. But we also need to
> protect against an unconditional load being converted into a predicated
> load for partial loop vectorisation. I think we still need a check in
> check_load_store_for_partial_vectors to handle that. The check wouldn't
> prevent vectorisation, it would just prevent using fully-predicated loops.
But that seems to check for availability of the masked gather IFN which
of course isn't available and then sets
LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P to false:
if (memory_access_type == VMAT_LOAD_STORE_LANES)
{
if (is_load
? !vect_load_lanes_supported (vectype, group_size, true)
: !vect_store_lanes_supported (vectype, group_size, true))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"can't operate on partial vectors because"
" the target doesn't have an appropriate"
" load/store-lanes instruction.\n");
LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
return;
Richard.
> Thanks,
> Richard
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
