Richard Biener <rguent...@suse.de> writes:
> 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:
Ah, yeah, OK. I wrongly thought that the relaxed check for gather/scatter
support might have affected that too.
Should be OK then. :-)
Richard
