On November 7, 2019 4:14:14 PM GMT+01:00, Richard Sandiford
<richard.sandif...@arm.com> wrote:
>Richard Biener <richard.guent...@gmail.com> writes:
>> On Tue, Nov 5, 2019 at 3:25 PM Richard Sandiford
>> <richard.sandif...@arm.com> wrote:
>>>
>>> This patch makes two tweaks to vectorizable_conversion. The first
>>> is to use "modifier" to distinguish between promotion, demotion,
>>> and neither promotion nor demotion, rather than using a code for
>>> some cases and "modifier" for others. The second is to take ncopies
>>> into account for the promotion and demotion costs; previously we
>gave
>>> multiple copies the same cost as a single copy.
>>>
>>> Later patches test this, but it seemed worth splitting out.
>>
>> OK, but does ncopies properly handle unrolling with SLP?
>
>Bah, thanks for catching that. Here's a fixed version, tested as
>before.
OK.
Thanks,
Richard.
>Richard
>
>
>2019-11-07 Richard Sandiford <richard.sandif...@arm.com>
>
>gcc/
> * tree-vect-stmts.c (vect_model_promotion_demotion_cost): Take the
> number of ncopies as an additional argument.
> (vectorizable_conversion): Update call accordingly. Use "modifier"
> to check whether a conversion is between vectors with the same
> numbers of units.
>
>Index: gcc/tree-vect-stmts.c
>===================================================================
>--- gcc/tree-vect-stmts.c 2019-11-07 15:11:49.000000000 +0000
>+++ gcc/tree-vect-stmts.c 2019-11-07 15:11:50.134775028 +0000
>@@ -917,26 +917,27 @@ vect_model_simple_cost (stmt_vec_info st
> }
>
>
>-/* Model cost for type demotion and promotion operations. PWR is
>normally
>- zero for single-step promotions and demotions. It will be one if
>- two-step promotion/demotion is required, and so on. Each
>additional
>+/* Model cost for type demotion and promotion operations. PWR is
>+ normally zero for single-step promotions and demotions. It will be
>+ one if two-step promotion/demotion is required, and so on. NCOPIES
>+ is the number of vector results (and thus number of instructions)
>+ for the narrowest end of the operation chain. Each additional
> step doubles the number of instructions required. */
>
> static void
> vect_model_promotion_demotion_cost (stmt_vec_info stmt_info,
>- enum vect_def_type *dt, int pwr,
>+ enum vect_def_type *dt,
>+ unsigned int ncopies, int pwr,
> stmt_vector_for_cost *cost_vec)
> {
>- int i, tmp;
>+ int i;
> int inside_cost = 0, prologue_cost = 0;
>
> for (i = 0; i < pwr + 1; i++)
> {
>- tmp = (STMT_VINFO_TYPE (stmt_info) ==
>type_promotion_vec_info_type) ?
>- (i + 1) : i;
>- inside_cost += record_stmt_cost (cost_vec, vect_pow2 (tmp),
>- vec_promote_demote, stmt_info, 0,
>- vect_body);
>+ inside_cost += record_stmt_cost (cost_vec, ncopies,
>vec_promote_demote,
>+ stmt_info, 0, vect_body);
>+ ncopies *= 2;
> }
>
> /* FORNOW: Assuming maximum 2 args per stmts. */
>@@ -4964,7 +4965,7 @@ vectorizable_conversion (stmt_vec_info s
> if (!vec_stmt) /* transformation not required. */
> {
> DUMP_VECT_SCOPE ("vectorizable_conversion");
>- if (code == FIX_TRUNC_EXPR || code == FLOAT_EXPR)
>+ if (modifier == NONE)
> {
> STMT_VINFO_TYPE (stmt_info) = type_conversion_vec_info_type;
> vect_model_simple_cost (stmt_info, ncopies, dt, ndts, slp_node,
>@@ -4973,14 +4974,24 @@ vectorizable_conversion (stmt_vec_info s
> else if (modifier == NARROW)
> {
> STMT_VINFO_TYPE (stmt_info) = type_demotion_vec_info_type;
>- vect_model_promotion_demotion_cost (stmt_info, dt, multi_step_cvt,
>- cost_vec);
>+ /* The final packing step produces one vector result per copy. */
>+ unsigned int nvectors
>+ = (slp_node ? SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node) : ncopies);
>+ vect_model_promotion_demotion_cost (stmt_info, dt, nvectors,
>+ multi_step_cvt, cost_vec);
> }
> else
> {
> STMT_VINFO_TYPE (stmt_info) = type_promotion_vec_info_type;
>- vect_model_promotion_demotion_cost (stmt_info, dt, multi_step_cvt,
>- cost_vec);
>+ /* The initial unpacking step produces two vector results
>+ per copy. MULTI_STEP_CVT is 0 for a single conversion,
>+ so >> MULTI_STEP_CVT divides by 2^(number of steps - 1). */
>+ unsigned int nvectors
>+ = (slp_node
>+ ? SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node) >> multi_step_cvt
>+ : ncopies * 2);
>+ vect_model_promotion_demotion_cost (stmt_info, dt, nvectors,
>+ multi_step_cvt, cost_vec);
> }
> interm_types.release ();
> return true;
