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.
Thanks,
Richard
