Re: [PATCH 4/9] vect: Adjust vectorizable_load costing on VMAT_ELEMENTWISE and VMAT_STRIDED_SLP

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Richard,

on 2023/7/2 16:58, Richard Sandiford wrote:
> Kewen Lin <linkw@linux.ibm.com> writes:
>> @@ -9743,11 +9739,23 @@ vectorizable_load (vec_info *vinfo,
>>        unsigned int n_groups = 0;
>>        for (j = 0; j < ncopies; j++)
>>  	{
>> -	  if (nloads > 1)
>> +	  if (nloads > 1 && !costing_p)
>>  	    vec_alloc (v, nloads);
>>  	  gimple *new_stmt = NULL;
>>  	  for (i = 0; i < nloads; i++)
>>  	    {
>> +	      if (costing_p)
>> +		{
>> +		  if (VECTOR_TYPE_P (ltype))
>> +		    vect_get_load_cost (vinfo, stmt_info, 1,
>> +					alignment_support_scheme, misalignment,
>> +					false, &inside_cost, nullptr, cost_vec,
>> +					cost_vec, true);
>> +		  else
>> +		    inside_cost += record_stmt_cost (cost_vec, 1, scalar_load,
>> +						     stmt_info, 0, vect_body);
>> +		  continue;
>> +		}
> 
> Just a note that this might make life harder for AArch64 costing.
> Strided SLP loads are still equivalent to vector loads for AArch64,
> since they happen on the FPR/vector side even if they have integral
> modes.
> 
> But I agree this is more accurate from a general target-independent POV,
> especially given the relatively coarse-grain costing enum.  So I think
> that's just something AArch64 will need to account for.

Sorry for the inconvenience.  Hope accounting for it with target hook on
vect costing isn't very complicated.

BR,
Kewen