schedule.c

   1 /*
   2  * Copyright 2010-2011 INRIA Saclay
   3  * Copyright 2021      Sven Verdoolaege
   4  *
   5  * Use of this software is governed by the MIT license
   6  *
   7  * Written by Sven Verdoolaege, INRIA Saclay - Ile-de-France,
   8  * Parc Club Orsay Universite, ZAC des vignes, 4 rue Jacques Monod,
   9  * 91893 Orsay, France
  10  */
  11
  12 #include <ctype.h>
  13 #include <stdio.h>
  14 #include <string.h>
  15
  16 #include <isl/aff.h>
  17 #include <isl/set.h>
  18 #include <isl/map.h>
  19 #include <isl/constraint.h>
  20 #include <isl/union_set.h>
  21 #include <isl/union_map.h>
  22
  23 #include "grouping.h"
  24 #include "schedule.h"
  25
  26 /* Add parameters with identifiers "ids" to "set".
  27  */
  28 static __isl_give isl_set *add_params(__isl_take isl_set *set,
  29         __isl_keep isl_id_list *ids)
  30 {
  31         int i, n;
  32         unsigned nparam;
  33
  34         n = isl_id_list_n_id(ids);
  35
  36         nparam = isl_set_dim(set, isl_dim_param);
  37         set = isl_set_add_dims(set, isl_dim_param, n);
  38
  39         for (i = 0; i < n; ++i) {
  40                 isl_id *id;
  41
  42                 id = isl_id_list_get_id(ids, i);
  43                 set = isl_set_set_dim_id(set, isl_dim_param, nparam + i, id);
  44         }
  45
  46         return set;
  47 }
  48
  49 /* Equate the dimensions of "set" starting at "first" to
  50  * freshly created parameters with identifiers "ids".
  51  * The number of equated dimensions is equal to the number of elements in "ids".
  52  */
  53 static __isl_give isl_set *parametrize(__isl_take isl_set *set,
  54         int first, __isl_keep isl_id_list *ids)
  55 {
  56         int i, n;
  57         unsigned nparam;
  58
  59         nparam = isl_set_dim(set, isl_dim_param);
  60
  61         set = add_params(set, ids);
  62
  63         n = isl_id_list_n_id(ids);
  64         for (i = 0; i < n; ++i)
  65                 set = isl_set_equate(set, isl_dim_param, nparam + i,
  66                                         isl_dim_set, first + i);
  67
  68         return set;
  69 }
  70
  71 /* Given a parameter space "space", create a set of dimension "len"
  72  * of which the dimensions starting at "first" are equated to
  73  * freshly created parameters with identifiers "ids".
  74  */
  75 __isl_give isl_set *parametrization(__isl_take isl_space *space,
  76         int len, int first, __isl_keep isl_id_list *ids)
  77 {
  78         isl_set *set;
  79
  80         space = isl_space_set_from_params(space);
  81         space = isl_space_add_dims(space, isl_dim_set, len);
  82         set = isl_set_universe(space);
  83
  84         return parametrize(set, first, ids);
  85 }
  86
  87 /* Load and return a schedule from a file called "filename".
  88  */
  89 static __isl_give isl_schedule *load_schedule(isl_ctx *ctx,
  90         const char *filename)
  91 {
  92         FILE *file;
  93         isl_schedule *schedule;
  94
  95         file = fopen(filename, "r");
  96         if (!file) {
  97                 fprintf(stderr, "Unable to open '%s' for reading\n", filename);
  98                 return NULL;
  99         }
 100         schedule = isl_schedule_read_from_file(ctx, file);
 101         fclose(file);
 102
 103         return schedule;
 104 }
 105
 106 /* Save the schedule "schedule" to a file called "filename".
 107  * The schedule is printed in block style.
 108  */
 109 static void save_schedule(__isl_keep isl_schedule *schedule,
 110         const char *filename)
 111 {
 112         FILE *file;
 113         isl_ctx *ctx;
 114         isl_printer *p;
 115
 116         if (!schedule)
 117                 return;
 118
 119         file = fopen(filename, "w");
 120         if (!file) {
 121                 fprintf(stderr, "Unable to open '%s' for writing\n", filename);
 122                 return;
 123         }
 124         ctx = isl_schedule_get_ctx(schedule);
 125         p = isl_printer_to_file(ctx, file);
 126         p = isl_printer_set_yaml_style(p, ISL_YAML_STYLE_BLOCK);
 127         p = isl_printer_print_schedule(p, schedule);
 128         isl_printer_free(p);
 129         fclose(file);
 130 }
 131
 132 /* Compute a schedule on the domain of "sc" that respects the schedule
 133  * constraints in "sc", without trying to combine groups of statements.
 134  */
 135 __isl_give isl_schedule *ppcg_compute_non_grouping_schedule(
 136         __isl_take isl_schedule_constraints *sc, struct ppcg_options *options)
 137 {
 138         if (options->debug->dump_schedule_constraints)
 139                 isl_schedule_constraints_dump(sc);
 140         return isl_schedule_constraints_compute_schedule(sc);
 141 }
 142
 143 /* Compute a schedule on the domain of "sc" that respects the schedule
 144  * constraints in "sc".
 145  *
 146  * "schedule" is a known correct schedule that is used to combine
 147  * groups of statements if options->group_chains is set.
 148  */
 149 __isl_give isl_schedule *ppcg_compute_schedule(
 150         __isl_take isl_schedule_constraints *sc,
 151         __isl_keep isl_schedule *schedule, struct ppcg_options *options)
 152 {
 153         if (options->group_chains)
 154                 return ppcg_compute_grouping_schedule(sc, schedule, options);
 155         return ppcg_compute_non_grouping_schedule(sc, options);
 156 }
 157
 158 /* Obtain a schedule, either by reading it form a file
 159  * or by computing it using "compute".
 160  * Also take care of saving the computed schedule and/or
 161  * dumping the obtained schedule if requested by the user.
 162  */
 163 __isl_give isl_schedule *ppcg_get_schedule(isl_ctx *ctx,
 164         struct ppcg_options *options,
 165         __isl_give isl_schedule *(*compute)(void *user), void *user)
 166 {
 167         isl_schedule *schedule;
 168
 169         if (options->load_schedule_file) {
 170                 schedule = load_schedule(ctx, options->load_schedule_file);
 171         } else {
 172                 schedule = compute(user);
 173                 if (options->save_schedule_file)
 174                         save_schedule(schedule, options->save_schedule_file);
 175         }
 176         if (options->debug->dump_schedule)
 177                 isl_schedule_dump(schedule);
 178
 179         return schedule;
 180 }
 181
 182 /* Mark all dimensions in the band node "node" to be of "type".
 183  */
 184 __isl_give isl_schedule_node *ppcg_set_schedule_node_type(
 185         __isl_take isl_schedule_node *node, enum isl_ast_loop_type type)
 186 {
 187         int i, n;
 188
 189         n = isl_schedule_node_band_n_member(node);
 190         for (i = 0; i < n; ++i)
 191                 node = isl_schedule_node_band_member_set_ast_loop_type(node, i,
 192                                                         type);
 193
 194         return node;
 195 }
 196
 197 /* Does "tile" represent a trivial lattice tile, i.e.,
 198  * one with size 1 in all directions?
 199  */
 200 static isl_bool lattice_is_trivial(__isl_keep isl_fixed_box *tile)
 201 {
 202         isl_bool trivial;
 203         isl_val *val_one;
 204         isl_multi_val *size;
 205         isl_multi_val *zero, *one;
 206
 207         size = isl_fixed_box_get_size(tile);
 208         zero = isl_multi_val_sub(isl_multi_val_copy(size),
 209                                  isl_multi_val_copy(size));
 210         val_one = isl_val_one(isl_fixed_box_get_ctx(tile));
 211         one = isl_multi_val_add_val(zero, val_one);
 212         trivial = isl_multi_val_plain_is_equal(size, one);
 213         isl_multi_val_free(size);
 214         isl_multi_val_free(one);
 215
 216         return trivial;
 217 }
 218
 219 /* Given that the elements of "set" lie on a (rectangular) lattice
 220  * with tile "tile", scale it down such that the origin of the result
 221  * corresponds to "tile".
 222  *
 223  * The lattice is of the form
 224  *
 225  *      offset + size j
 226  *
 227  * Plug this into "set" to obtain a set in terms of "j"
 228  * with j = 0 corresponding to offset in "set".
 229  */
 230 static __isl_give isl_set *scale_down_set(__isl_keep isl_fixed_box *tile,
 231         __isl_take isl_set *set)
 232 {
 233         isl_space *space;
 234         isl_multi_val *size;
 235         isl_multi_aff *offset;
 236         isl_multi_aff *id;
 237         isl_multi_aff *to_lattice;
 238
 239         size = isl_fixed_box_get_size(tile);
 240         offset = isl_fixed_box_get_offset(tile);
 241         space = isl_multi_aff_get_space(offset);
 242         id = isl_space_identity_multi_aff_on_domain(isl_space_copy(space));
 243         offset = isl_multi_aff_insert_domain(offset, space);
 244         to_lattice = isl_multi_aff_scale_multi_val(id, size);
 245         to_lattice = isl_multi_aff_add(to_lattice, offset);
 246         set = isl_set_preimage_multi_aff(set, to_lattice);
 247
 248         return set;
 249 }
 250
 251 /* Given that the schedule values of the band node "node"
 252  * lie on a (rectangular) lattice with tile "tile",
 253  * scale it down such that the values corresponding to "tile"
 254  * are mapped to the origin.
 255  * "domain" is the (universe) domain reaching "node".
 256  *
 257  * The lattice is of the form
 258  *
 259  *      offset + size j
 260  *
 261  * Subtract offset and scale down by size.
 262  */
 263 static __isl_give isl_schedule_node *scale_down_band(
 264         __isl_keep isl_fixed_box *tile, __isl_take isl_schedule_node *node,
 265         __isl_keep isl_union_set *domain)
 266 {
 267         isl_multi_val *size;
 268         isl_multi_aff *offset;
 269         isl_multi_union_pw_aff *mupa;
 270
 271         size = isl_fixed_box_get_size(tile);
 272         offset = isl_multi_aff_neg(isl_fixed_box_get_offset(tile));
 273         domain = isl_union_set_copy(domain);
 274         mupa = isl_multi_union_pw_aff_multi_aff_on_domain(domain, offset);
 275         node = isl_schedule_node_band_shift(node, mupa);
 276         node = isl_schedule_node_band_scale_down(node, size);
 277
 278         return node;
 279 }
 280
 281 /* Try and shift the given band node to the origin after
 282  * potentially scaling it down first.
 283  *
 284  * In particular, obtain the set of schedule values and
 285  * first check if they lie on a non-trivial (rectangular) lattice.
 286  * If so, scale down both the band node and the set.  Then
 287  * compute the element-wise minimal value, which may
 288  * depend on the parameters.
 289  * If this results in any piecewise expressions,
 290  * then do not perform any shifting as that may
 291  * very well make the resulting code more complicated.
 292  * Otherwise shift the band by the opposite of this minimal value.
 293  */
 294 static __isl_give isl_schedule_node *scale_down_and_shift_to_origin(
 295         __isl_take isl_schedule_node *node)
 296 {
 297         isl_bool is_multi_aff, trivial;
 298         isl_space *space;
 299         isl_union_set *domain, *range;
 300         isl_union_map *partial;
 301         isl_set *min_domain;
 302         isl_set *set;
 303         isl_multi_pw_aff *min;
 304         isl_multi_aff *min_ma, *shift;
 305         isl_multi_union_pw_aff *mupa;
 306         isl_fixed_box *tile;
 307
 308         partial = isl_schedule_node_band_get_partial_schedule_union_map(node);
 309         domain = isl_schedule_node_get_domain(node);
 310         range = isl_union_set_apply(isl_union_set_copy(domain), partial);
 311         space = isl_schedule_node_band_get_space(node);
 312         set = isl_union_set_extract_set(range, space);
 313         isl_union_set_free(range);
 314         domain = isl_union_set_universe(domain);
 315
 316         tile = isl_set_get_lattice_tile(set);
 317         trivial = lattice_is_trivial(tile);
 318         if (trivial < 0) {
 319                 node = isl_schedule_node_free(node);
 320         } else if (!trivial) {
 321                 set = scale_down_set(tile, set);
 322                 node = scale_down_band(tile, node, domain);
 323         }
 324         isl_fixed_box_free(tile);
 325
 326         min = isl_set_min_multi_pw_aff(set);
 327         min_domain = isl_multi_pw_aff_domain(isl_multi_pw_aff_copy(min));
 328         min = isl_multi_pw_aff_gist(min, min_domain);
 329         is_multi_aff = isl_multi_pw_aff_isa_multi_aff(min);
 330         if (is_multi_aff < 0 || !is_multi_aff) {
 331                 isl_union_set_free(domain);
 332                 isl_multi_pw_aff_free(min);
 333                 if (is_multi_aff < 0)
 334                         return isl_schedule_node_free(node);
 335                 return node;
 336         }
 337
 338         min_ma = isl_multi_pw_aff_as_multi_aff(min);
 339         shift = isl_multi_aff_neg(min_ma);
 340         mupa = isl_multi_union_pw_aff_multi_aff_on_domain(domain, shift);
 341         node = isl_schedule_node_band_shift(node, mupa);
 342
 343         return node;
 344 }
 345
 346 /* Tile "node" with tile sizes "sizes", but first try and shift the band
 347  * to the origin.
 348  * Tiling a band that does not start at the origin is likely
 349  * to result in initial partial tiles.
 350  */
 351 __isl_give isl_schedule_node *ppcg_tile(__isl_take isl_schedule_node *node,
 352         __isl_take isl_multi_val *sizes)
 353 {
 354         node = scale_down_and_shift_to_origin(node);
 355         return isl_schedule_node_band_tile(node, sizes);
 356 }