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

[Richard Sandiford <richard.sandiford@arm.com>]

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.

Thanks,
Richard