On 1/10/24 15:40, 钟居哲 wrote:
> I need to add these costs for segment load/stores:
>
> /* Generic costs for VLA vector operations. */
> static const scalable_vector_cost generic_vla_vector_cost = {
> {
> 1,/* int_stmt_cost */
> 1,/* fp_stmt_cost */
> 1,/* gather_load_cost */
> 1,/* scatter_store_cost */
> 1,/* vec_to_scalar_cost */
> 1,/* scalar_to_vec_cost */
> 1,/* permute_cost */
> 1,/* align_load_cost */
> 1,/* align_store_cost */
> 2,/* unalign_load_cost */
> 2,/* unalign_store_cost */
> },
> 2,/* vlseg2_vsseg2_permute_cost */
> 2,/* vlseg3_vsseg3_permute_cost */
> 3,/* vlseg4_vsseg4_permute_cost */
> 3,/* vlseg5_vsseg5_permute_cost */
> 4,/* vlseg6_vsseg6_permute_cost */
> 4,/* vlseg7_vsseg7_permute_cost */
> 4,/* vlseg8_vsseg8_permute_cost */
> };
>
> to fix the SLP issues in the following patches.
>
> If you don't allow me to switch to generic vector cost model and tune it.
> How can I fix the FAILs of slp-*.c cases ?
>
> Currently, l let all slp-*.c tests all XFAIL which definitely incorrect.
Of course we don't want those XFAILs. It's not a matter of "allowing"
or not but rather that I'd like to understand the reasoning. The patch
itself seems reasonable to me apart from not really getting the
intention.
Your main point seems to be
> + const cpu_vector_cost *costs = tune_param->vec_costs;
> + if (!costs)
> + return &generic_vector_cost
and that is fine. What's not clear is whether changing the actual
costs is a temporary thing or whether it is supposed to be another
fallback. If they are going to be changed anyway, why do we need
to revert to the default model now? As discussed yesterday
increased permute costs and vec_to_scalar costs make sense, to first
order. Is that because of dynamic-lmul2-7.c?
Generally we need to make the costs dependent on the
type or mode of course, just as we started to do with the latencies.
Permute is particularly sensitive as you already gathered.
Regards
Robin
