Richard Biener <rguent...@suse.de> writes:
> On Fri, 11 Aug 2023, juzhe.zh...@rivai.ai wrote:
>
>> Hi, Richi.
>>
>> > 1. Target is using loop MASK as the partial vector loop control.
>> >> I don't think it checks for this?
>>
>> I am not sure whether I understand EXTRACT_LAST correctly.
>> But if target doesn't use loop MASK for partial vector loop control, how
>> does target use EXTRACT_LAST?
>> Since EXTRACT_LAST is always extracting the last element of the vector
>> according to MASK operand.
>>
>> > But we don't really know this at this point? The only thing we know
>> > is that nothing set LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P to false.
>>
>> Yes. So I am try to use 'get_len_load_store' to check whether target support
>> LEN loop control.
>>
>> Well, I admit it's not a good idea.
>>
>>
>> > I think it should work to change the direct_internal_fn_supported_p
>> > check for IFN_EXTRACT_LAST to a "poitive" one guarding
>>
>> > gcc_assert (ncopies == 1 && !slp_node);
>> > vect_record_loop_mask (loop_vinfo,
>> > &LOOP_VINFO_MASKS (loop_vinfo),
>> > 1, vectype, NULL);
>>
>> > and in the else branch check for VEC_EXTRACT support and if present
>> > record a loop len. Just in this case this particular order would
>> > be important.
>>
>> Do you mean change the codes as follows :?
>>
>> - if (!direct_internal_fn_supported_p (IFN_EXTRACT_LAST, vectype,
>> - OPTIMIZE_FOR_SPEED))
>> - {
>> - if (dump_enabled_p ())
>> - dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> - "can't operate on partial vectors "
>> - "because the target doesn't support extract
>> "
>> - "last reduction.\n");
>> - LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
>> - }
>> - else if (slp_node)
>> if (slp_node)
>> {
>> if (dump_enabled_p ())
>> dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> "can't operate on partial vectors "
>> "because an SLP statement is live after "
>> "the loop.\n");
>> LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
>> }
>> else if (ncopies > 1)
>> {
>> if (dump_enabled_p ())
>> dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> "can't operate on partial vectors "
>> "because ncopies is greater than 1.\n");
>> LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
>> }
>> else
>> {
>> gcc_assert (ncopies == 1 && !slp_node);
>> if (direct_internal_fn_supported_p (IFN_EXTRACT_LAST, vectype,
>> OPTIMIZE_FOR_SPEED))
>> vect_record_loop_mask (loop_vinfo,
>> &LOOP_VINFO_MASKS (loop_vinfo),
>> 1, vectype, NULL);
>> else
>
> check here the target supports VEC_EXTRACT
>
>> vect_record_loop_len (loop_vinfo,
>> &LOOP_VINFO_LENS (loop_vinfo),
>> 1, vectype, 1);
>
> else set LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P to false with a
> diagnostic.
I agree with all this FWIW. That is, the check should be based on
.VEC_EXTRACT alone, but .EXTRACT_LAST should take priority (not least
because SVE provides both .VEC_EXTRACT and .EXTRACT_LAST).
Thanks,
Richard
