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Vector peeling cost model 6/6 

gcc/ChangeLog:

2017-05-24  Robin Dapp  <rdapp@linux.vnet.ibm.com>

	* tree-vect-data-refs.c (vect_get_peeling_costs_all_drs):
	Introduce unknown_misalignment parameter and remove vf.
	(vect_peeling_hash_get_lowest_cost):
	Pass unknown_misalignment parameter.
	(vect_enhance_data_refs_alignment):
	Fix unsupportable data ref treatment.

From-SVN: r248680
This commit is contained in:
Robin Dapp 2017-05-30 11:02:14 +00:00 committed by Andreas Krebbel
parent 4bfb347c02
commit 4d3d23fb7d
2 changed files with 80 additions and 42 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2017-05-24 Robin Dapp <rdapp@linux.vnet.ibm.com>
* tree-vect-data-refs.c (vect_get_peeling_costs_all_drs):
Introduce unknown_misalignment parameter and remove vf.
(vect_peeling_hash_get_lowest_cost):
Pass unknown_misalignment parameter.
(vect_enhance_data_refs_alignment):
Fix unsupportable data ref treatment.
2017-05-30 Robin Dapp <rdapp@linux.vnet.ibm.com>
* tree-vect-data-refs.c (vect_get_data_access_cost):

113
gcc/tree-vect-data-refs.c
View File

@ -1239,14 +1239,16 @@ vect_peeling_hash_get_most_frequent (_vect_peel_info **slot,
}
/* Get the costs of peeling NPEEL iterations checking data access costs
for all data refs. */
for all data refs. If UNKNOWN_MISALIGNMENT is true, we assume DR0's
misalignment will be zero after peeling. */
static void
vect_get_peeling_costs_all_drs (struct data_reference *dr0,
unsigned int *inside_cost,
unsigned int *outside_cost,
stmt_vector_for_cost *body_cost_vec,
unsigned int npeel, unsigned int vf)
unsigned int npeel,
bool unknown_misalignment)
{
gimple *stmt = DR_STMT (dr0);
stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
@ -1274,7 +1276,7 @@ vect_get_peeling_costs_all_drs (struct data_reference *dr0,
int save_misalignment;
save_misalignment = DR_MISALIGNMENT (dr);
if (dr == dr0 && npeel == vf / 2)
if (unknown_misalignment && dr == dr0)
SET_DR_MISALIGNMENT (dr, 0);
else
vect_update_misalignment_for_peel (dr, dr0, npeel);
@ -1305,7 +1307,7 @@ vect_peeling_hash_get_lowest_cost (_vect_peel_info **slot,
epilogue_cost_vec.create (2);
vect_get_peeling_costs_all_drs (elem->dr, &inside_cost, &outside_cost,
&body_cost_vec, elem->npeel, 0);
&body_cost_vec, elem->npeel, false);
outside_cost += vect_get_known_peeling_cost
(loop_vinfo, elem->npeel, &dummy,
@ -1517,6 +1519,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
{
vec<data_reference_p> datarefs = LOOP_VINFO_DATAREFS (loop_vinfo);
struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
enum dr_alignment_support supportable_dr_alignment;
struct data_reference *dr0 = NULL, *first_store = NULL;
struct data_reference *dr;
unsigned int i, j;
@ -1528,6 +1531,8 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
unsigned int npeel = 0;
bool one_misalignment_known = false;
bool one_misalignment_unknown = false;
bool one_dr_unsupportable = false;
struct data_reference *unsupportable_dr = NULL;
unsigned int vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
unsigned possible_npeel_number = 1;
tree vectype;
@ -1599,6 +1604,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
&& !STMT_VINFO_GROUPED_ACCESS (stmt_info))
continue;
supportable_dr_alignment = vect_supportable_dr_alignment (dr, true);
do_peeling = vector_alignment_reachable_p (dr);
if (do_peeling)
{
@ -1637,8 +1643,8 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
else
possible_npeel_number = vf / nelements;
/* NPEEL_TMP is 0 when there is no misalignment, increment
the peeling amount by one in order to ... */
/* NPEEL_TMP is 0 when there is no misalignment, but also
allow peeling NELEMENTS. */
if (DR_MISALIGNMENT (dr) == 0)
possible_npeel_number++;
}
@ -1684,10 +1690,18 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
dr0 = dr;
}
one_misalignment_unknown = true;
/* Check for data refs with unsupportable alignment that
can be peeled. */
if (!supportable_dr_alignment)
{
one_dr_unsupportable = true;
unsupportable_dr = dr;
}
if (!first_store && DR_IS_WRITE (dr))
first_store = dr;
one_misalignment_unknown = true;
}
}
else
@ -1732,7 +1746,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
vect_get_peeling_costs_all_drs (dr0,
&load_inside_cost,
&load_outside_cost,
&dummy, vf / 2, vf);
&dummy, vf / 2, true);
dummy.release ();
if (first_store)
@ -1741,7 +1755,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
vect_get_peeling_costs_all_drs (first_store,
&store_inside_cost,
&store_outside_cost,
&dummy, vf / 2, vf);
&dummy, vf / 2, true);
dummy.release ();
}
else
@ -1805,43 +1819,59 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
if (peel_for_known_alignment.peel_info.dr != NULL
&& peel_for_unknown_alignment.inside_cost
>= peel_for_known_alignment.inside_cost)
best_peel = peel_for_known_alignment;
{
best_peel = peel_for_known_alignment;
/* Calculate the penalty for no peeling, i.e. leaving everything
unaligned.
TODO: use something like an adapted vect_get_peeling_costs_all_drs. */
unsigned nopeel_inside_cost = 0;
unsigned nopeel_outside_cost = 0;
/* If the best peeling for known alignment has NPEEL == 0, perform no
peeling at all except if there is an unsupportable dr that we can
align. */
if (best_peel.peel_info.npeel == 0 && !one_dr_unsupportable)
do_peeling = false;
}
stmt_vector_for_cost dummy;
dummy.create (2);
FOR_EACH_VEC_ELT (datarefs, i, dr)
vect_get_data_access_cost (dr, &nopeel_inside_cost,
&nopeel_outside_cost, &dummy);
dummy.release ();
/* If there is an unsupportable data ref, prefer this over all choices so far
since we'd have to discard a chosen peeling except when it accidentally
aligned the unsupportable data ref. */
if (one_dr_unsupportable)
dr0 = unsupportable_dr;
else if (do_peeling)
{
/* Calculate the penalty for no peeling, i.e. leaving everything
unaligned.
TODO: Adapt vect_get_peeling_costs_all_drs and use here. */
unsigned nopeel_inside_cost = 0;
unsigned nopeel_outside_cost = 0;
/* Add epilogue costs. As we do not peel for alignment here, no prologue
costs will be recorded. */
stmt_vector_for_cost prologue_cost_vec, epilogue_cost_vec;
prologue_cost_vec.create (2);
epilogue_cost_vec.create (2);
stmt_vector_for_cost dummy;
dummy.create (2);
FOR_EACH_VEC_ELT (datarefs, i, dr)
vect_get_data_access_cost (dr, &nopeel_inside_cost,
&nopeel_outside_cost, &dummy);
dummy.release ();
int dummy2;
nopeel_outside_cost += vect_get_known_peeling_cost
(loop_vinfo, 0, &dummy2,
&LOOP_VINFO_SCALAR_ITERATION_COST (loop_vinfo),
&prologue_cost_vec, &epilogue_cost_vec);
/* Add epilogue costs. As we do not peel for alignment here, no prologue
costs will be recorded. */
stmt_vector_for_cost prologue_cost_vec, epilogue_cost_vec;
prologue_cost_vec.create (2);
epilogue_cost_vec.create (2);
prologue_cost_vec.release ();
epilogue_cost_vec.release ();
int dummy2;
nopeel_outside_cost += vect_get_known_peeling_cost
(loop_vinfo, 0, &dummy2,
&LOOP_VINFO_SCALAR_ITERATION_COST (loop_vinfo),
&prologue_cost_vec, &epilogue_cost_vec);
npeel = best_peel.peel_info.npeel;
dr0 = best_peel.peel_info.dr;
prologue_cost_vec.release ();
epilogue_cost_vec.release ();
/* If no peeling is not more expensive than the best peeling we
have so far, don't perform any peeling. */
if (nopeel_inside_cost <= best_peel.inside_cost)
do_peeling = false;
npeel = best_peel.peel_info.npeel;
dr0 = best_peel.peel_info.dr;
/* If no peeling is not more expensive than the best peeling we
have so far, don't perform any peeling. */
if (nopeel_inside_cost <= best_peel.inside_cost)
do_peeling = false;
}
if (do_peeling)
{
@ -2019,8 +2049,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
break;
}
enum dr_alignment_support supportable_dr_alignment =
vect_supportable_dr_alignment (dr, false);
supportable_dr_alignment = vect_supportable_dr_alignment (dr, false);
if (!supportable_dr_alignment)
{