gcc/graphite-dependences.c

   1 /* Data dependence analysis for Graphite.
   2    Copyright (C) 2009 Free Software Foundation, Inc.
   3    Contributed by Sebastian Pop <sebastian.pop@amd.com> and
   4    Konrad Trifunovic <konrad.trifunovic@inria.fr>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "ggc.h"
  27 #include "tree.h"
  28 #include "rtl.h"
  29 #include "basic-block.h"
  30 #include "diagnostic.h"
  31 #include "tree-flow.h"
  32 #include "toplev.h"
  33 #include "tree-dump.h"
  34 #include "timevar.h"
  35 #include "cfgloop.h"
  36 #include "tree-chrec.h"
  37 #include "tree-data-ref.h"
  38 #include "tree-scalar-evolution.h"
  39 #include "tree-pass.h"
  40 #include "domwalk.h"
  41 #include "pointer-set.h"
  42 #include "gimple.h"
  43
  44 #ifdef HAVE_cloog
  45 #include "cloog/cloog.h"
  46 #include "ppl_c.h"
  47 #include "sese.h"
  48 #include "graphite-ppl.h"
  49 #include "graphite.h"
  50 #include "graphite-poly.h"
  51 #include "graphite-dependences.h"
  52
  53 /* Returns a new polyhedral Data Dependence Relation (DDR).  SOURCE is
  54    the source data reference, SINK is the sink data reference.  SOURCE
  55    and SINK define an edge in the Data Dependence Graph (DDG).  */
  56
  57 static poly_ddr_p
  58 new_poly_ddr (poly_dr_p source, poly_dr_p sink,
  59               ppl_Pointset_Powerset_C_Polyhedron_t ddp)
  60 {
  61   poly_ddr_p pddr;
  62
  63   pddr = XNEW (struct poly_ddr);
  64   PDDR_SOURCE (pddr) = source;
  65   PDDR_SINK (pddr) = sink;
  66   PDDR_DDP (pddr) = ddp;
  67   PDDR_KIND (pddr) = unknown_dependence;
  68
  69   return pddr;
  70 }
  71
  72 /* Free the poly_ddr_p P.  */
  73
  74 void
  75 free_poly_ddr (void *p)
  76 {
  77   poly_ddr_p pddr = (poly_ddr_p) p;
  78   ppl_delete_Pointset_Powerset_C_Polyhedron (PDDR_DDP (pddr));
  79   free (pddr);
  80 }
  81
  82 /* Comparison function for poly_ddr hash table.  */
  83
  84 int
  85 eq_poly_ddr_p (const void *pddr1, const void *pddr2)
  86 {
  87   const struct poly_ddr *p1 = (const struct poly_ddr *) pddr1;
  88   const struct poly_ddr *p2 = (const struct poly_ddr *) pddr2;
  89
  90   return (PDDR_SOURCE (p1) == PDDR_SOURCE (p2)
  91           && PDDR_SINK (p1) == PDDR_SINK (p2));
  92 }
  93
  94 /* Hash function for poly_ddr hashtable.  */
  95
  96 hashval_t
  97 hash_poly_ddr_p (const void *pddr)
  98 {
  99   const struct poly_ddr *p = (const struct poly_ddr *) pddr;
 100
 101   return (hashval_t) ((long) PDDR_SOURCE (p) + (long) PDDR_SINK (p));
 102 }
 103
 104 /* Returns true when PDDR has no dependence.  */
 105
 106 static bool
 107 pddr_is_empty (poly_ddr_p pddr)
 108 {
 109   if (PDDR_KIND (pddr) != unknown_dependence)
 110     return PDDR_KIND (pddr) == no_dependence ? true : false;
 111
 112   if (ppl_Pointset_Powerset_C_Polyhedron_is_empty (PDDR_DDP (pddr)))
 113     {
 114       PDDR_KIND (pddr) = no_dependence;
 115       return true;
 116     }
 117
 118   PDDR_KIND (pddr) = has_dependence;
 119   return false;
 120 }
 121
 122 /* Returns a polyhedron of dimension DIM.
 123
 124    Maps the dimensions [0, ..., cut - 1] of polyhedron P to OFFSET0
 125    and the dimensions [cut, ..., nb_dim] to DIM - GDIM.  */
 126
 127 static ppl_Pointset_Powerset_C_Polyhedron_t
 128 map_into_dep_poly (graphite_dim_t dim, graphite_dim_t gdim,
 129                    ppl_Pointset_Powerset_C_Polyhedron_t p,
 130                    graphite_dim_t cut,
 131                    graphite_dim_t offset)
 132 {
 133   ppl_Pointset_Powerset_C_Polyhedron_t res;
 134
 135   ppl_new_Pointset_Powerset_C_Polyhedron_from_Pointset_Powerset_C_Polyhedron
 136     (&res, p);
 137   ppl_insert_dimensions_pointset (res, 0, offset);
 138   ppl_insert_dimensions_pointset (res, offset + cut,
 139                                   dim - offset - cut - gdim);
 140
 141   return res;
 142 }
 143
 144 /* Swap [cut0, ..., cut1] to the end of DR: "a CUT0 b CUT1 c" is
 145    transformed into "a CUT0 c CUT1' b"
 146
 147    Add NB0 zeros before "a":  "00...0 a CUT0 c CUT1' b"
 148    Add NB1 zeros between "a" and "c":  "00...0 a 00...0 c CUT1' b"
 149    Add DIM - NB0 - NB1 - PDIM zeros between "c" and "b":
 150    "00...0 a 00...0 c 00...0 b".  */
 151
 152 static ppl_Pointset_Powerset_C_Polyhedron_t
 153 map_dr_into_dep_poly (graphite_dim_t dim,
 154                       ppl_Pointset_Powerset_C_Polyhedron_t dr,
 155                       graphite_dim_t cut0, graphite_dim_t cut1,
 156                       graphite_dim_t nb0, graphite_dim_t nb1)
 157 {
 158   ppl_dimension_type pdim;
 159   ppl_dimension_type *map;
 160   ppl_Pointset_Powerset_C_Polyhedron_t res;
 161   ppl_dimension_type i;
 162
 163   ppl_new_Pointset_Powerset_C_Polyhedron_from_Pointset_Powerset_C_Polyhedron
 164     (&res, dr);
 165   ppl_Pointset_Powerset_C_Polyhedron_space_dimension (res, &pdim);
 166
 167   map = (ppl_dimension_type *) XNEWVEC (ppl_dimension_type, pdim);
 168
 169   /* First mapping: move 'g' vector to right position.  */
 170   for (i = 0; i < cut0; i++)
 171     map[i] = i;
 172
 173   for (i = cut0; i < cut1; i++)
 174     map[i] = pdim - cut1 + i;
 175
 176   for (i = cut1; i < pdim; i++)
 177     map[i] = cut0 + i - cut1;
 178
 179   ppl_Pointset_Powerset_C_Polyhedron_map_space_dimensions (res, map, pdim);
 180   free (map);
 181
 182   /* After swapping 's' and 'g' vectors, we have to update a new cut.  */
 183   cut1 = pdim - cut1 + cut0;
 184
 185   ppl_insert_dimensions_pointset (res, 0, nb0);
 186   ppl_insert_dimensions_pointset (res, nb0 + cut0, nb1);
 187   ppl_insert_dimensions_pointset (res, nb0 + nb1 + cut1,
 188                                   dim - nb0 - nb1 - pdim);
 189
 190   return res;
 191 }
 192
 193 /* Builds a constraints of the form "POS1 - POS2 CSTR_TYPE C" */
 194
 195 static ppl_Constraint_t
 196 build_pairwise_constraint (graphite_dim_t dim,
 197                            graphite_dim_t pos1, graphite_dim_t pos2,
 198                            int c, enum ppl_enum_Constraint_Type cstr_type)
 199 {
 200   ppl_Linear_Expression_t expr;
 201   ppl_Constraint_t cstr;
 202   ppl_Coefficient_t coef;
 203   Value v, v_op, v_c;
 204
 205   value_init (v);
 206   value_init (v_op);
 207   value_init (v_c);
 208
 209   value_set_si (v, 1);
 210   value_set_si (v_op, -1);
 211   value_set_si (v_c, c);
 212
 213   ppl_new_Coefficient (&coef);
 214   ppl_new_Linear_Expression_with_dimension (&expr, dim);
 215
 216   ppl_assign_Coefficient_from_mpz_t (coef, v);
 217   ppl_Linear_Expression_add_to_coefficient (expr, pos1, coef);
 218   ppl_assign_Coefficient_from_mpz_t (coef, v_op);
 219   ppl_Linear_Expression_add_to_coefficient (expr, pos2, coef);
 220   ppl_assign_Coefficient_from_mpz_t (coef, v_c);
 221   ppl_Linear_Expression_add_to_inhomogeneous (expr, coef);
 222
 223   ppl_new_Constraint (&cstr, expr, cstr_type);
 224
 225   ppl_delete_Linear_Expression (expr);
 226   ppl_delete_Coefficient (coef);
 227   value_clear (v);
 228   value_clear (v_op);
 229   value_clear (v_c);
 230
 231   return cstr;
 232 }
 233
 234 /* Builds subscript equality constraints.  */
 235
 236 static ppl_Pointset_Powerset_C_Polyhedron_t
 237 dr_equality_constraints (graphite_dim_t dim,
 238                          graphite_dim_t pos, graphite_dim_t nb_subscripts)
 239 {
 240   ppl_Polyhedron_t subscript_equalities;
 241   ppl_Pointset_Powerset_C_Polyhedron_t res;
 242   Value v, v_op;
 243   graphite_dim_t i;
 244
 245   value_init (v);
 246   value_init (v_op);
 247   value_set_si (v, 1);
 248   value_set_si (v_op, -1);
 249
 250   ppl_new_C_Polyhedron_from_space_dimension (&subscript_equalities, dim, 0);
 251   for (i = 0; i < nb_subscripts; i++)
 252     {
 253       ppl_Linear_Expression_t expr;
 254       ppl_Constraint_t cstr;
 255       ppl_Coefficient_t coef;
 256
 257       ppl_new_Coefficient (&coef);
 258       ppl_new_Linear_Expression_with_dimension (&expr, dim);
 259
 260       ppl_assign_Coefficient_from_mpz_t (coef, v);
 261       ppl_Linear_Expression_add_to_coefficient (expr, pos + i, coef);
 262       ppl_assign_Coefficient_from_mpz_t (coef, v_op);
 263       ppl_Linear_Expression_add_to_coefficient (expr, pos + i + nb_subscripts,
 264                                                 coef);
 265
 266       ppl_new_Constraint (&cstr, expr, PPL_CONSTRAINT_TYPE_EQUAL);
 267       ppl_Polyhedron_add_constraint (subscript_equalities, cstr);
 268
 269       ppl_delete_Linear_Expression (expr);
 270       ppl_delete_Constraint (cstr);
 271       ppl_delete_Coefficient (coef);
 272     }
 273
 274   ppl_new_Pointset_Powerset_C_Polyhedron_from_C_Polyhedron
 275     (&res, subscript_equalities);
 276   value_clear (v);
 277   value_clear (v_op);
 278   ppl_delete_Polyhedron (subscript_equalities);
 279
 280   return res;
 281 }
 282
 283 /* Builds scheduling equality constraints.  */
 284
 285 static ppl_Pointset_Powerset_C_Polyhedron_t
 286 build_pairwise_scheduling_equality (graphite_dim_t dim,
 287                                     graphite_dim_t pos, graphite_dim_t offset)
 288 {
 289   ppl_Pointset_Powerset_C_Polyhedron_t res;
 290   ppl_Polyhedron_t equalities;
 291   ppl_Constraint_t cstr;
 292
 293   ppl_new_C_Polyhedron_from_space_dimension (&equalities, dim, 0);
 294
 295   cstr = build_pairwise_constraint (dim, pos, pos + offset, 0,
 296                                     PPL_CONSTRAINT_TYPE_EQUAL);
 297   ppl_Polyhedron_add_constraint (equalities, cstr);
 298   ppl_delete_Constraint (cstr);
 299
 300   ppl_new_Pointset_Powerset_C_Polyhedron_from_C_Polyhedron (&res, equalities);
 301   ppl_delete_Polyhedron (equalities);
 302   return res;
 303 }
 304
 305 /* Builds scheduling inequality constraints.  */
 306
 307 static ppl_Pointset_Powerset_C_Polyhedron_t
 308 build_pairwise_scheduling_inequality (graphite_dim_t dim,
 309                                       graphite_dim_t pos,
 310                                       graphite_dim_t offset,
 311                                       bool direction)
 312 {
 313   ppl_Pointset_Powerset_C_Polyhedron_t res;
 314   ppl_Polyhedron_t equalities;
 315   ppl_Constraint_t cstr;
 316
 317   ppl_new_C_Polyhedron_from_space_dimension (&equalities, dim, 0);
 318
 319   if (direction)
 320     cstr = build_pairwise_constraint (dim, pos, pos + offset, -1,
 321                                       PPL_CONSTRAINT_TYPE_GREATER_OR_EQUAL);
 322   else
 323     cstr = build_pairwise_constraint (dim, pos, pos + offset, 1,
 324                                       PPL_CONSTRAINT_TYPE_LESS_OR_EQUAL);
 325
 326   ppl_Polyhedron_add_constraint (equalities, cstr);
 327   ppl_delete_Constraint (cstr);
 328
 329   ppl_new_Pointset_Powerset_C_Polyhedron_from_C_Polyhedron (&res, equalities);
 330   ppl_delete_Polyhedron (equalities);
 331   return res;
 332 }
 333
 334 /* Returns true when adding the lexicographical constraints at level I
 335    to the RES dependence polyhedron returns an empty polyhedron.  */
 336
 337 static bool
 338 lexicographically_gt_p (ppl_Pointset_Powerset_C_Polyhedron_t res,
 339                         graphite_dim_t dim,
 340                         graphite_dim_t offset,
 341                         bool direction, graphite_dim_t i)
 342 {
 343   ppl_Pointset_Powerset_C_Polyhedron_t ineq;
 344   bool empty_p;
 345
 346   ineq = build_pairwise_scheduling_inequality (dim, i, offset,
 347                                                direction);
 348   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (ineq, res);
 349   empty_p = ppl_Pointset_Powerset_C_Polyhedron_is_empty (ineq);
 350   if (!empty_p)
 351     ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, ineq);
 352   ppl_delete_Pointset_Powerset_C_Polyhedron (ineq);
 353
 354   return !empty_p;
 355 }
 356
 357 /* Build the precedence constraints for the lexicographical comparison
 358    of time vectors RES following the lexicographical order.  */
 359
 360 static void
 361 build_lexicographically_gt_constraint (ppl_Pointset_Powerset_C_Polyhedron_t *res,
 362                                        graphite_dim_t dim,
 363                                        graphite_dim_t tdim1,
 364                                        graphite_dim_t offset,
 365                                        bool direction)
 366 {
 367   graphite_dim_t i;
 368
 369   if (lexicographically_gt_p (*res, dim, offset, direction, 0))
 370     return;
 371
 372   for (i = 0; i < tdim1 - 1; i++)
 373     {
 374       ppl_Pointset_Powerset_C_Polyhedron_t sceq;
 375
 376       sceq = build_pairwise_scheduling_equality (dim, i, offset);
 377       ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (*res, sceq);
 378       ppl_delete_Pointset_Powerset_C_Polyhedron (sceq);
 379
 380       if (lexicographically_gt_p (*res, dim, offset, direction, i + 1))
 381         return;
 382     }
 383
 384   if (i == tdim1 - 1)
 385     {
 386       ppl_delete_Pointset_Powerset_C_Polyhedron (*res);
 387       ppl_new_Pointset_Powerset_C_Polyhedron_from_space_dimension (res, dim, 1);
 388     }
 389 }
 390
 391 /* Build the dependence polyhedron for data references PDR1 and PDR2.  */
 392
 393 static poly_ddr_p
 394 dependence_polyhedron_1 (poly_bb_p pbb1, poly_bb_p pbb2,
 395                          ppl_Pointset_Powerset_C_Polyhedron_t d1,
 396                          ppl_Pointset_Powerset_C_Polyhedron_t d2,
 397                          poly_dr_p pdr1, poly_dr_p pdr2,
 398                          ppl_Polyhedron_t s1, ppl_Polyhedron_t s2,
 399                          bool direction,
 400                          bool original_scattering_p)
 401 {
 402   scop_p scop = PBB_SCOP (pbb1);
 403   graphite_dim_t tdim1 = original_scattering_p ?
 404     pbb_nb_scattering_orig (pbb1) : pbb_nb_scattering_transform (pbb1);
 405   graphite_dim_t tdim2 = original_scattering_p ?
 406     pbb_nb_scattering_orig (pbb2) : pbb_nb_scattering_transform (pbb2);
 407   graphite_dim_t ddim1 = pbb_dim_iter_domain (pbb1);
 408   graphite_dim_t ddim2 = pbb_dim_iter_domain (pbb2);
 409   graphite_dim_t sdim1 = PDR_NB_SUBSCRIPTS (pdr1) + 1;
 410   graphite_dim_t gdim = scop_nb_params (scop);
 411   graphite_dim_t dim1 = pdr_dim (pdr1);
 412   graphite_dim_t dim2 = pdr_dim (pdr2);
 413   graphite_dim_t dim = tdim1 + tdim2 + dim1 + dim2;
 414   ppl_Pointset_Powerset_C_Polyhedron_t res;
 415   ppl_Pointset_Powerset_C_Polyhedron_t id1, id2, isc1, isc2, idr1, idr2;
 416   ppl_Pointset_Powerset_C_Polyhedron_t sc1, sc2, dreq;
 417
 418   gcc_assert (PBB_SCOP (pbb1) == PBB_SCOP (pbb2));
 419   ppl_new_Pointset_Powerset_C_Polyhedron_from_C_Polyhedron (&sc1, s1);
 420   ppl_new_Pointset_Powerset_C_Polyhedron_from_C_Polyhedron (&sc2, s2);
 421
 422   id1 = map_into_dep_poly (dim, gdim, d1, ddim1, tdim1);
 423   id2 = map_into_dep_poly (dim, gdim, d2, ddim2, tdim1 + ddim1 + tdim2);
 424   isc1 = map_into_dep_poly (dim, gdim, sc1, ddim1 + tdim1, 0);
 425   isc2 = map_into_dep_poly (dim, gdim, sc2, ddim2 + tdim2, tdim1 + ddim1);
 426
 427   idr1 = map_dr_into_dep_poly (dim, PDR_ACCESSES (pdr1), ddim1, ddim1 + gdim,
 428                                tdim1, tdim2 + ddim2);
 429   idr2 = map_dr_into_dep_poly (dim, PDR_ACCESSES (pdr2), ddim2, ddim2 + gdim,
 430                                tdim1 + ddim1 + tdim2, sdim1);
 431
 432   /* Now add the subscript equalities.  */
 433   dreq = dr_equality_constraints (dim, tdim1 + ddim1 + tdim2 + ddim2, sdim1);
 434
 435   ppl_new_Pointset_Powerset_C_Polyhedron_from_space_dimension (&res, dim, 0);
 436   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, id1);
 437   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, id2);
 438   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, isc1);
 439   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, isc2);
 440   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, idr1);
 441   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, idr2);
 442   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (res, dreq);
 443   ppl_delete_Pointset_Powerset_C_Polyhedron (id1);
 444   ppl_delete_Pointset_Powerset_C_Polyhedron (id2);
 445   ppl_delete_Pointset_Powerset_C_Polyhedron (sc1);
 446   ppl_delete_Pointset_Powerset_C_Polyhedron (sc2);
 447   ppl_delete_Pointset_Powerset_C_Polyhedron (isc1);
 448   ppl_delete_Pointset_Powerset_C_Polyhedron (isc2);
 449   ppl_delete_Pointset_Powerset_C_Polyhedron (idr1);
 450   ppl_delete_Pointset_Powerset_C_Polyhedron (idr2);
 451   ppl_delete_Pointset_Powerset_C_Polyhedron (dreq);
 452
 453   if (!ppl_Pointset_Powerset_C_Polyhedron_is_empty (res))
 454     build_lexicographically_gt_constraint (&res, dim, MIN (tdim1, tdim2),
 455                                            tdim1 + ddim1, direction);
 456
 457   return new_poly_ddr (pdr1, pdr2, res);
 458 }
 459
 460 /* Build the dependence polyhedron for data references PDR1 and PDR2.
 461    If possible use already cached information.  */
 462
 463 static poly_ddr_p
 464 dependence_polyhedron (poly_bb_p pbb1, poly_bb_p pbb2,
 465                        ppl_Pointset_Powerset_C_Polyhedron_t d1,
 466                        ppl_Pointset_Powerset_C_Polyhedron_t d2,
 467                        poly_dr_p pdr1, poly_dr_p pdr2,
 468                        ppl_Polyhedron_t s1, ppl_Polyhedron_t s2,
 469                        bool direction,
 470                        bool original_scattering_p)
 471 {
 472   PTR *x = NULL;
 473   poly_ddr_p res;
 474
 475   if (original_scattering_p)
 476     {
 477       struct poly_ddr tmp;
 478
 479       tmp.source = pdr1;
 480       tmp.sink = pdr2;
 481       x = htab_find_slot (SCOP_ORIGINAL_PDDRS (PBB_SCOP (pbb1)),
 482                           &tmp, INSERT);
 483
 484       if (x && *x)
 485         return (poly_ddr_p) *x;
 486     }
 487
 488   res = dependence_polyhedron_1 (pbb1, pbb2, d1, d2, pdr1, pdr2,
 489                                  s1, s2, direction, original_scattering_p);
 490
 491   if (original_scattering_p)
 492     *x = res;
 493
 494   return res;
 495 }
 496
 497 /* Returns the PDDR corresponding to the original schedule, or NULL if
 498    the dependence relation is empty.  */
 499
 500 static poly_ddr_p
 501 pddr_original_scattering (poly_bb_p pbb1, poly_bb_p pbb2,
 502                           poly_dr_p pdr1, poly_dr_p pdr2)
 503 {
 504   poly_ddr_p pddr;
 505   ppl_Pointset_Powerset_C_Polyhedron_t d1 = PBB_DOMAIN (pbb1);
 506   ppl_Pointset_Powerset_C_Polyhedron_t d2 = PBB_DOMAIN (pbb2);
 507   ppl_Polyhedron_t so1 = PBB_ORIGINAL_SCATTERING (pbb1);
 508   ppl_Polyhedron_t so2 = PBB_ORIGINAL_SCATTERING (pbb2);
 509
 510   if (PDR_NB_SUBSCRIPTS (pdr1) != PDR_NB_SUBSCRIPTS (pdr2))
 511     return NULL;
 512
 513   pddr = dependence_polyhedron (pbb1, pbb2, d1, d2, pdr1, pdr2, so1, so2,
 514                                 true, true);
 515   if (pddr_is_empty (pddr))
 516     return NULL;
 517
 518   return pddr;
 519 }
 520
 521 /* Returns true when the PBB_TRANSFORMED_SCATTERING functions of PBB1
 522    and PBB2 respect the data dependences of PBB_ORIGINAL_SCATTERING
 523    functions.  */
 524
 525 static bool
 526 graphite_legal_transform_dr (poly_bb_p pbb1, poly_bb_p pbb2,
 527                              poly_dr_p pdr1, poly_dr_p pdr2)
 528 {
 529   ppl_Polyhedron_t st1, st2;
 530   ppl_Pointset_Powerset_C_Polyhedron_t po, pt;
 531   graphite_dim_t ddim1, otdim1, otdim2, ttdim1, ttdim2;
 532   ppl_Pointset_Powerset_C_Polyhedron_t temp;
 533   ppl_dimension_type pdim;
 534   bool is_empty_p;
 535   poly_ddr_p pddr;
 536   ppl_Pointset_Powerset_C_Polyhedron_t d1 = PBB_DOMAIN (pbb1);
 537   ppl_Pointset_Powerset_C_Polyhedron_t d2 = PBB_DOMAIN (pbb2);
 538
 539   pddr = pddr_original_scattering (pbb1, pbb2, pdr1, pdr2);
 540   if (!pddr)
 541     return true;
 542
 543   po = PDDR_DDP (pddr);
 544
 545   if (dump_file && (dump_flags & TDF_DETAILS))
 546     fprintf (dump_file, "\nloop carries dependency.\n");
 547
 548   st1 = PBB_TRANSFORMED_SCATTERING (pbb1);
 549   st2 = PBB_TRANSFORMED_SCATTERING (pbb2);
 550   ddim1 = pbb_dim_iter_domain (pbb1);
 551   otdim1 = pbb_nb_scattering_orig (pbb1);
 552   otdim2 = pbb_nb_scattering_orig (pbb2);
 553   ttdim1 = pbb_nb_scattering_transform (pbb1);
 554   ttdim2 = pbb_nb_scattering_transform (pbb2);
 555
 556   /* Copy the PO polyhedron into the TEMP, so it is not destroyed.
 557      Keep in mind, that PO polyhedron might be restored from the cache
 558      and should not be modified!  */
 559   ppl_Pointset_Powerset_C_Polyhedron_space_dimension (po, &pdim);
 560   ppl_new_Pointset_Powerset_C_Polyhedron_from_space_dimension (&temp, pdim, 0);
 561   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (temp, po);
 562
 563   pddr = dependence_polyhedron (pbb1, pbb2, d1, d2, pdr1, pdr2, st1, st2,
 564                                 false, false);
 565   pt = PDDR_DDP (pddr);
 566
 567   /* Extend PO and PT to have the same dimensions.  */
 568   ppl_insert_dimensions_pointset (temp, otdim1, ttdim1);
 569   ppl_insert_dimensions_pointset (temp, otdim1 + ttdim1 + ddim1 + otdim2, ttdim2);
 570   ppl_insert_dimensions_pointset (pt, 0, otdim1);
 571   ppl_insert_dimensions_pointset (pt, otdim1 + ttdim1 + ddim1, otdim2);
 572
 573   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (temp, pt);
 574   is_empty_p = ppl_Pointset_Powerset_C_Polyhedron_is_empty (temp);
 575
 576   ppl_delete_Pointset_Powerset_C_Polyhedron (temp);
 577   free_poly_ddr (pddr);
 578
 579   return is_empty_p;
 580 }
 581
 582 /* Iterates over the data references of PBB1 and PBB2 and detect
 583    whether the transformed schedule is correct.  */
 584
 585 static bool
 586 graphite_legal_transform_bb (poly_bb_p pbb1, poly_bb_p pbb2)
 587 {
 588   int i, j;
 589   poly_dr_p pdr1, pdr2;
 590
 591   for (i = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb1), i, pdr1); i++)
 592     for (j = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb2), j, pdr2); j++)
 593       if (!graphite_legal_transform_dr (pbb1, pbb2, pdr1, pdr2))
 594         return false;
 595
 596   return true;
 597 }
 598
 599 /* Iterates over the SCOP and detect whether the transformed schedule
 600    is correct.  */
 601
 602 bool
 603 graphite_legal_transform (scop_p scop)
 604 {
 605   int i, j;
 606   poly_bb_p pbb1, pbb2;
 607
 608   timevar_push (TV_GRAPHITE_DATA_DEPS);
 609
 610   for (i = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), i, pbb1); i++)
 611     for (j = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), j, pbb2); j++)
 612       if (!graphite_legal_transform_bb (pbb1, pbb2))
 613         {
 614           timevar_pop (TV_GRAPHITE_DATA_DEPS);
 615           return false;
 616         }
 617
 618   timevar_pop (TV_GRAPHITE_DATA_DEPS);
 619   return true;
 620 }
 621
 622 /* Remove all the dimensions except alias information at dimension
 623    ALIAS_DIM.  */
 624
 625 static void
 626 build_alias_set_powerset (ppl_Pointset_Powerset_C_Polyhedron_t alias_powerset,
 627                           ppl_dimension_type alias_dim)
 628 {
 629   ppl_dimension_type *ds;
 630   ppl_dimension_type access_dim;
 631   unsigned i, pos = 0;
 632
 633   ppl_Pointset_Powerset_C_Polyhedron_space_dimension (alias_powerset,
 634                                                       &access_dim);
 635   ds = XNEWVEC (ppl_dimension_type, access_dim-1);
 636   for (i = 0; i < access_dim; i++)
 637     {
 638       if (i == alias_dim)
 639         continue;
 640
 641       ds[pos] = i;
 642       pos++;
 643     }
 644
 645   ppl_Pointset_Powerset_C_Polyhedron_remove_space_dimensions (alias_powerset,
 646                                                               ds,
 647                                                               access_dim - 1);
 648   free (ds);
 649 }
 650
 651 /* Return true when PDR1 and PDR2 may alias.  */
 652
 653 static bool
 654 poly_drs_may_alias_p (poly_dr_p pdr1, poly_dr_p pdr2)
 655 {
 656   ppl_Pointset_Powerset_C_Polyhedron_t alias_powerset1, alias_powerset2;
 657   ppl_Pointset_Powerset_C_Polyhedron_t accesses1 = PDR_ACCESSES (pdr1);
 658   ppl_Pointset_Powerset_C_Polyhedron_t accesses2 = PDR_ACCESSES (pdr2);
 659   ppl_dimension_type alias_dim1 = pdr_alias_set_dim (pdr1);
 660   ppl_dimension_type alias_dim2 = pdr_alias_set_dim (pdr2);
 661   int empty_p;
 662
 663   ppl_new_Pointset_Powerset_C_Polyhedron_from_Pointset_Powerset_C_Polyhedron
 664     (&alias_powerset1, accesses1);
 665   ppl_new_Pointset_Powerset_C_Polyhedron_from_Pointset_Powerset_C_Polyhedron
 666     (&alias_powerset2, accesses2);
 667
 668   build_alias_set_powerset (alias_powerset1, alias_dim1);
 669   build_alias_set_powerset (alias_powerset2, alias_dim2);
 670
 671   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign
 672     (alias_powerset1, alias_powerset2);
 673
 674   empty_p = ppl_Pointset_Powerset_C_Polyhedron_is_empty (alias_powerset1);
 675
 676   ppl_delete_Pointset_Powerset_C_Polyhedron (alias_powerset1);
 677   ppl_delete_Pointset_Powerset_C_Polyhedron (alias_powerset2);
 678
 679   return !empty_p;
 680 }
 681
 682 /* Returns TRUE when the dependence polyhedron between PDR1 and
 683    PDR2 represents a loop carried dependence at level LEVEL.  */
 684
 685 static bool
 686 graphite_carried_dependence_level_k (poly_dr_p pdr1, poly_dr_p pdr2,
 687                                      int level)
 688 {
 689   poly_bb_p pbb1 = PDR_PBB (pdr1);
 690   poly_bb_p pbb2 = PDR_PBB (pdr2);
 691   ppl_Pointset_Powerset_C_Polyhedron_t d1 = PBB_DOMAIN (pbb1);
 692   ppl_Pointset_Powerset_C_Polyhedron_t d2 = PBB_DOMAIN (pbb2);
 693   ppl_Polyhedron_t so1 = PBB_TRANSFORMED_SCATTERING (pbb1);
 694   ppl_Polyhedron_t so2 = PBB_TRANSFORMED_SCATTERING (pbb2);
 695   ppl_Pointset_Powerset_C_Polyhedron_t po;
 696   ppl_Pointset_Powerset_C_Polyhedron_t eqpp;
 697   graphite_dim_t tdim1 = pbb_nb_scattering_transform (pbb1);
 698   graphite_dim_t ddim1 = pbb_dim_iter_domain (pbb1);
 699   ppl_dimension_type dim;
 700   bool empty_p;
 701   poly_ddr_p pddr;
 702
 703   if ((PDR_TYPE (pdr1) == PDR_READ && PDR_TYPE (pdr2) == PDR_READ)
 704       || !poly_drs_may_alias_p (pdr1, pdr2))
 705     return false;
 706
 707   if (PDR_NB_SUBSCRIPTS (pdr1) != PDR_NB_SUBSCRIPTS (pdr2))
 708     return true;
 709
 710   pddr = dependence_polyhedron (pbb1, pbb2, d1, d2, pdr1, pdr2, so1, so2,
 711                                 true, false);
 712
 713   if (pddr_is_empty (pddr))
 714     return false;
 715
 716   po = PDDR_DDP (pddr);
 717   ppl_Pointset_Powerset_C_Polyhedron_space_dimension (po, &dim);
 718   eqpp = build_pairwise_scheduling_inequality (dim, level, tdim1 + ddim1, 1);
 719
 720   ppl_Pointset_Powerset_C_Polyhedron_intersection_assign (eqpp, po);
 721   empty_p = ppl_Pointset_Powerset_C_Polyhedron_is_empty (eqpp);
 722
 723   ppl_delete_Pointset_Powerset_C_Polyhedron (eqpp);
 724   return !empty_p;
 725 }
 726
 727 /* Check data dependency between PBB1 and PBB2 at level LEVEL.  */
 728
 729 bool
 730 dependency_between_pbbs_p (poly_bb_p pbb1, poly_bb_p pbb2, int level)
 731 {
 732   int i, j;
 733   poly_dr_p pdr1, pdr2;
 734
 735   timevar_push (TV_GRAPHITE_DATA_DEPS);
 736
 737   for (i = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb1), i, pdr1); i++)
 738     for (j = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb2), j, pdr2); j++)
 739       if (graphite_carried_dependence_level_k (pdr1, pdr2, level))
 740         {
 741           timevar_pop (TV_GRAPHITE_DATA_DEPS);
 742           return true;
 743         }
 744
 745   timevar_pop (TV_GRAPHITE_DATA_DEPS);
 746   return false;
 747 }
 748
 749 /* Pretty print to FILE all the data dependences of SCoP in DOT
 750    format.  */
 751
 752 static void
 753 dot_deps_1 (FILE *file, scop_p scop)
 754 {
 755   int i, j, k, l;
 756   poly_bb_p pbb1, pbb2;
 757   poly_dr_p pdr1, pdr2;
 758
 759   fputs ("digraph all {\n", file);
 760
 761   for (i = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), i, pbb1); i++)
 762     for (j = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), j, pbb2); j++)
 763       for (k = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb1), k, pdr1); k++)
 764         for (l = 0; VEC_iterate (poly_dr_p, PBB_DRS (pbb2), l, pdr2); l++)
 765           if (pddr_original_scattering (pbb1, pbb2, pdr1, pdr2))
 766             fprintf (file, "S%d_D%d -> S%d_D%d\n",
 767                      pbb_index (pbb1), PDR_ID (pdr1),
 768                      pbb_index (pbb2), PDR_ID (pdr2));
 769
 770   fputs ("}\n\n", file);
 771 }
 772
 773 /* Display all the data dependences in SCoP using dotty.  */
 774
 775 void
 776 dot_deps (scop_p scop)
 777 {
 778   /* When debugging, enable the following code.  This cannot be used
 779      in production compilers because it calls "system".  */
 780 #if 0
 781   int x;
 782   FILE *stream = fopen ("/tmp/scopdeps.dot", "w");
 783   gcc_assert (stream);
 784
 785   dot_deps_1 (stream, scop);
 786   fclose (stream);
 787
 788   x = system ("dotty /tmp/scopdeps.dot");
 789 #else
 790   dot_deps_1 (stderr, scop);
 791 #endif
 792 }
 793
 794
 795 #endif