From: Robin Dapp Date: Tue, 30 May 2017 10:59:07 +0000 (+0000) Subject: Vector peeling cost model 4/6 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=64812d33ac6c0f23a3f4c25bc5497d7bb00e0f24;p=gcc.git Vector peeling cost model 4/6 gcc/ChangeLog: 2017-05-30 Robin Dapp * tree-vect-data-refs.c (vect_get_data_access_cost): Workaround for SLP handling. (vect_enhance_data_refs_alignment): Compute costs for doing no peeling at all, compare to the best peeling costs so far and avoid peeling if cheaper. From-SVN: r248678 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a5af5a44203..3d9fc12ad5c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2017-05-30 Robin Dapp + + * tree-vect-data-refs.c (vect_get_data_access_cost): + Workaround for SLP handling. + (vect_enhance_data_refs_alignment): + Compute costs for doing no peeling at all, compare to the best + peeling costs so far and avoid peeling if cheaper. + 2017-05-30 Robin Dapp * tree-vect-data-refs.c (vect_peeling_hash_choose_best_peeling): diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c index 1ae71cc6c04..1fa0386def6 100644 --- a/gcc/tree-vect-data-refs.c +++ b/gcc/tree-vect-data-refs.c @@ -1134,7 +1134,7 @@ vect_get_data_access_cost (struct data_reference *dr, int nunits = TYPE_VECTOR_SUBPARTS (STMT_VINFO_VECTYPE (stmt_info)); loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info); int vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo); - int ncopies = vf / nunits; + int ncopies = MAX (1, vf / nunits); /* TODO: Handle SLP properly */ if (DR_IS_READ (dr)) vect_get_load_cost (dr, ncopies, true, inside_cost, outside_cost, @@ -1517,10 +1517,8 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo) { vec 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; - struct data_reference *dr0_known_align = NULL; unsigned int i, j; bool do_peeling = false; bool do_versioning = false; @@ -1601,7 +1599,6 @@ 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) { @@ -1690,16 +1687,6 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo) if (!first_store && DR_IS_WRITE (dr)) first_store = dr; - /* If there are both known and unknown misaligned accesses in the - loop, we choose peeling amount according to the known - accesses. */ - if (!supportable_dr_alignment) - { - dr0 = dr; - if (!first_store && DR_IS_WRITE (dr)) - first_store = dr; - } - one_misalignment_unknown = true; } } @@ -1721,81 +1708,85 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo) || loop->inner) do_peeling = false; - unsigned int unknown_align_inside_cost = INT_MAX; - unsigned int unknown_align_outside_cost = INT_MAX; + struct _vect_peel_extended_info peel_for_known_alignment; + struct _vect_peel_extended_info peel_for_unknown_alignment; + struct _vect_peel_extended_info best_peel; + + peel_for_unknown_alignment.inside_cost = INT_MAX; + peel_for_unknown_alignment.outside_cost = INT_MAX; + peel_for_unknown_alignment.peel_info.count = 0; if (do_peeling - && one_misalignment_unknown - && vect_supportable_dr_alignment (dr0, false)) + && one_misalignment_unknown) { /* Check if the target requires to prefer stores over loads, i.e., if misaligned stores are more expensive than misaligned loads (taking drs with same alignment into account). */ - if (first_store && DR_IS_READ (dr0)) - { - unsigned int load_inside_cost = 0; - unsigned int load_outside_cost = 0; - unsigned int store_inside_cost = 0; - unsigned int store_outside_cost = 0; - stmt_vector_for_cost dummy; - dummy.create (2); - vect_get_peeling_costs_all_drs (dr0, - &load_inside_cost, - &load_outside_cost, - &dummy, vf / 2, vf); - dummy.release (); - + unsigned int load_inside_cost = 0; + unsigned int load_outside_cost = 0; + unsigned int store_inside_cost = 0; + unsigned int store_outside_cost = 0; + + stmt_vector_for_cost dummy; + dummy.create (2); + vect_get_peeling_costs_all_drs (dr0, + &load_inside_cost, + &load_outside_cost, + &dummy, vf / 2, vf); + dummy.release (); + + if (first_store) + { dummy.create (2); vect_get_peeling_costs_all_drs (first_store, &store_inside_cost, &store_outside_cost, &dummy, vf / 2, vf); dummy.release (); + } + else + { + store_inside_cost = INT_MAX; + store_outside_cost = INT_MAX; + } - if (load_inside_cost > store_inside_cost - || (load_inside_cost == store_inside_cost - && load_outside_cost > store_outside_cost)) - { - dr0 = first_store; - unknown_align_inside_cost = store_inside_cost; - unknown_align_outside_cost = store_outside_cost; - } - else - { - unknown_align_inside_cost = load_inside_cost; - unknown_align_outside_cost = load_outside_cost; - } + if (load_inside_cost > store_inside_cost + || (load_inside_cost == store_inside_cost + && load_outside_cost > store_outside_cost)) + { + dr0 = first_store; + peel_for_unknown_alignment.inside_cost = store_inside_cost; + peel_for_unknown_alignment.outside_cost = store_outside_cost; + } + else + { + peel_for_unknown_alignment.inside_cost = load_inside_cost; + peel_for_unknown_alignment.outside_cost = load_outside_cost; + } - stmt_vector_for_cost prologue_cost_vec, epilogue_cost_vec; - prologue_cost_vec.create (2); - epilogue_cost_vec.create (2); + stmt_vector_for_cost prologue_cost_vec, epilogue_cost_vec; + prologue_cost_vec.create (2); + epilogue_cost_vec.create (2); - int dummy2; - unknown_align_outside_cost += vect_get_known_peeling_cost - (loop_vinfo, vf / 2, &dummy2, - &LOOP_VINFO_SCALAR_ITERATION_COST (loop_vinfo), - &prologue_cost_vec, &epilogue_cost_vec); + int dummy2; + peel_for_unknown_alignment.outside_cost += vect_get_known_peeling_cost + (loop_vinfo, vf / 2, &dummy2, + &LOOP_VINFO_SCALAR_ITERATION_COST (loop_vinfo), + &prologue_cost_vec, &epilogue_cost_vec); - prologue_cost_vec.release (); - epilogue_cost_vec.release (); - } + prologue_cost_vec.release (); + epilogue_cost_vec.release (); - /* Use peeling only if it may help to align other accesses in the loop or - if it may help improving load bandwith when we'd end up using - unaligned loads. */ - tree dr0_vt = STMT_VINFO_VECTYPE (vinfo_for_stmt (DR_STMT (dr0))); - if (STMT_VINFO_SAME_ALIGN_REFS - (vinfo_for_stmt (DR_STMT (dr0))).length () == 0 - && (vect_supportable_dr_alignment (dr0, false) - != dr_unaligned_supported - || (DR_IS_READ (dr0) - && (builtin_vectorization_cost (vector_load, dr0_vt, 0) - == builtin_vectorization_cost (unaligned_load, - dr0_vt, -1))))) - do_peeling = false; + peel_for_unknown_alignment.peel_info.count = 1 + + STMT_VINFO_SAME_ALIGN_REFS + (vinfo_for_stmt (DR_STMT (dr0))).length (); } - struct _vect_peel_extended_info peel_for_known_alignment; + peel_for_unknown_alignment.peel_info.npeel = 0; + peel_for_unknown_alignment.peel_info.dr = dr0; + + best_peel = peel_for_unknown_alignment; + peel_for_known_alignment.inside_cost = INT_MAX; peel_for_known_alignment.outside_cost = INT_MAX; peel_for_known_alignment.peel_info.count = 0; @@ -1804,24 +1795,52 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo) if (do_peeling && one_misalignment_known) { /* Peeling is possible, but there is no data access that is not supported - unless aligned. So we try to choose the best possible peeling. */ - - /* Choose the best peeling from the hash table. */ + unless aligned. So we try to choose the best possible peeling from + the hash table. */ peel_for_known_alignment = vect_peeling_hash_choose_best_peeling (&peeling_htab, loop_vinfo, &npeel, &body_cost_vec); - dr0_known_align = peel_for_known_alignment.peel_info.dr; } /* Compare costs of peeling for known and unknown alignment. */ - if (dr0_known_align != NULL - && unknown_align_inside_cost >= peel_for_known_alignment.inside_cost) - { - dr0 = dr0_known_align; - if (!npeel) - do_peeling = false; - } + 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; + + /* 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; + + 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 (); + + /* 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); + + 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); + + prologue_cost_vec.release (); + epilogue_cost_vec.release (); + + npeel = best_peel.peel_info.npeel; + dr0 = best_peel.peel_info.dr; - if (dr0 == NULL) + /* 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) @@ -2000,7 +2019,8 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo) break; } - supportable_dr_alignment = vect_supportable_dr_alignment (dr, false); + enum dr_alignment_support supportable_dr_alignment = + vect_supportable_dr_alignment (dr, false); if (!supportable_dr_alignment) {