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.
2019-11-05 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 2019-11-05 11:08:12.521631453 +0000
+++ gcc/tree-vect-stmts.c 2019-11-05 14:17:43.330141911 +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. */
@@ -4981,7 +4982,7 @@ 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,
@@ -4990,14 +4991,17 @@ 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. */
+ vect_model_promotion_demotion_cost (stmt_info, dt, ncopies,
+ 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. */
+ vect_model_promotion_demotion_cost (stmt_info, dt, ncopies * 2,
+ multi_step_cvt, cost_vec);
}
interm_types.release ();
return true;
