On Sun, Jun 10, 2012 at 5:58 PM, William J. Schmidt
<wschm...@linux.vnet.ibm.com> wrote:
> The fix for PR53331 caused a degradation to 187.facerec on
> powerpc64-unknown-linux-gnu. The following simple patch reverses the
> degradation without otherwise affecting SPEC cpu2000 or cpu2006.
> Bootstrapped and regtested on that platform with no new regressions. Ok
> for trunk?
Well, would the real cost not be subparts * scalar_to_vec plus
subparts * vec_perm?
At least vec_perm isn't the cost for building up a vector from N scalar elements
either (it might be close enough if subparts == 2). What's the case
with facerec
here? Does it have subparts == 2? I really wanted to pessimize this case
for say AVX and char elements, thus building up a vector from 32 scalars which
certainly does not cost a mere vec_perm. So, maybe special-case the
subparts == 2 case and assume vec_perm would match the cost only in that
case.
Thanks,
Richard.
> Thanks,
> Bill
>
>
> 2012-06-10 Bill Schmidt <wschm...@linux.ibm.com>
>
> * tree-vect-stmts.c (vect_model_load_cost): Change cost model
> for strided loads.
>
>
> Index: gcc/tree-vect-stmts.c
> ===================================================================
> --- gcc/tree-vect-stmts.c (revision 188341)
> +++ gcc/tree-vect-stmts.c (working copy)
> @@ -1031,11 +1031,10 @@ vect_model_load_cost (stmt_vec_info stmt_info, int
> /* The loads themselves. */
> if (STMT_VINFO_STRIDE_LOAD_P (stmt_info))
> {
> - /* N scalar loads plus gathering them into a vector.
> - ??? scalar_to_vec isn't the cost for that. */
> + /* N scalar loads plus gathering them into a vector. */
> inside_cost += (vect_get_stmt_cost (scalar_load) * ncopies
> * TYPE_VECTOR_SUBPARTS (STMT_VINFO_VECTYPE (stmt_info)));
> - inside_cost += ncopies * vect_get_stmt_cost (scalar_to_vec);
> + inside_cost += ncopies * vect_get_stmt_cost (vec_perm);
> }
> else
> vect_get_load_cost (first_dr, ncopies,
>
>
