gcc/omp-general.c

   1 /* General types and functions that are uselful for processing of OpenMP,
   2    OpenACC and similar directivers at various stages of compilation.
   3
   4    Copyright (C) 2005-2018 Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 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 /* Find an OMP clause of type KIND within CLAUSES.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "backend.h"
  28 #include "target.h"
  29 #include "tree.h"
  30 #include "gimple.h"
  31 #include "ssa.h"
  32 #include "diagnostic-core.h"
  33 #include "fold-const.h"
  34 #include "langhooks.h"
  35 #include "omp-general.h"
  36 #include "stringpool.h"
  37 #include "attribs.h"
  38
  39 tree
  40 omp_find_clause (tree clauses, enum omp_clause_code kind)
  41 {
  42   for (; clauses ; clauses = OMP_CLAUSE_CHAIN (clauses))
  43     if (OMP_CLAUSE_CODE (clauses) == kind)
  44       return clauses;
  45
  46   return NULL_TREE;
  47 }
  48
  49 /* Return true if DECL is a reference type.  */
  50
  51 bool
  52 omp_is_reference (tree decl)
  53 {
  54   return lang_hooks.decls.omp_privatize_by_reference (decl);
  55 }
  56
  57 /* Adjust *COND_CODE and *N2 so that the former is either LT_EXPR or
  58    GT_EXPR.  */
  59
  60 void
  61 omp_adjust_for_condition (location_t loc, enum tree_code *cond_code, tree *n2)
  62 {
  63   switch (*cond_code)
  64     {
  65     case LT_EXPR:
  66     case GT_EXPR:
  67     case NE_EXPR:
  68       break;
  69     case LE_EXPR:
  70       if (POINTER_TYPE_P (TREE_TYPE (*n2)))
  71         *n2 = fold_build_pointer_plus_hwi_loc (loc, *n2, 1);
  72       else
  73         *n2 = fold_build2_loc (loc, PLUS_EXPR, TREE_TYPE (*n2), *n2,
  74                                build_int_cst (TREE_TYPE (*n2), 1));
  75       *cond_code = LT_EXPR;
  76       break;
  77     case GE_EXPR:
  78       if (POINTER_TYPE_P (TREE_TYPE (*n2)))
  79         *n2 = fold_build_pointer_plus_hwi_loc (loc, *n2, -1);
  80       else
  81         *n2 = fold_build2_loc (loc, MINUS_EXPR, TREE_TYPE (*n2), *n2,
  82                                build_int_cst (TREE_TYPE (*n2), 1));
  83       *cond_code = GT_EXPR;
  84       break;
  85     default:
  86       gcc_unreachable ();
  87     }
  88 }
  89
  90 /* Return the looping step from INCR, extracted from the step of a gimple omp
  91    for statement.  */
  92
  93 tree
  94 omp_get_for_step_from_incr (location_t loc, tree incr)
  95 {
  96   tree step;
  97   switch (TREE_CODE (incr))
  98     {
  99     case PLUS_EXPR:
 100       step = TREE_OPERAND (incr, 1);
 101       break;
 102     case POINTER_PLUS_EXPR:
 103       step = fold_convert (ssizetype, TREE_OPERAND (incr, 1));
 104       break;
 105     case MINUS_EXPR:
 106       step = TREE_OPERAND (incr, 1);
 107       step = fold_build1_loc (loc, NEGATE_EXPR, TREE_TYPE (step), step);
 108       break;
 109     default:
 110       gcc_unreachable ();
 111     }
 112   return step;
 113 }
 114
 115 /* Extract the header elements of parallel loop FOR_STMT and store
 116    them into *FD.  */
 117
 118 void
 119 omp_extract_for_data (gomp_for *for_stmt, struct omp_for_data *fd,
 120                       struct omp_for_data_loop *loops)
 121 {
 122   tree t, var, *collapse_iter, *collapse_count;
 123   tree count = NULL_TREE, iter_type = long_integer_type_node;
 124   struct omp_for_data_loop *loop;
 125   int i;
 126   struct omp_for_data_loop dummy_loop;
 127   location_t loc = gimple_location (for_stmt);
 128   bool simd = gimple_omp_for_kind (for_stmt) & GF_OMP_FOR_SIMD;
 129   bool distribute = gimple_omp_for_kind (for_stmt)
 130                     == GF_OMP_FOR_KIND_DISTRIBUTE;
 131   bool taskloop = gimple_omp_for_kind (for_stmt)
 132                   == GF_OMP_FOR_KIND_TASKLOOP;
 133   tree iterv, countv;
 134
 135   fd->for_stmt = for_stmt;
 136   fd->pre = NULL;
 137   fd->have_nowait = distribute || simd;
 138   fd->have_ordered = false;
 139   fd->tiling = NULL_TREE;
 140   fd->collapse = 1;
 141   fd->ordered = 0;
 142   fd->sched_kind = OMP_CLAUSE_SCHEDULE_STATIC;
 143   fd->sched_modifiers = 0;
 144   fd->chunk_size = NULL_TREE;
 145   fd->simd_schedule = false;
 146   collapse_iter = NULL;
 147   collapse_count = NULL;
 148
 149   for (t = gimple_omp_for_clauses (for_stmt); t ; t = OMP_CLAUSE_CHAIN (t))
 150     switch (OMP_CLAUSE_CODE (t))
 151       {
 152       case OMP_CLAUSE_NOWAIT:
 153         fd->have_nowait = true;
 154         break;
 155       case OMP_CLAUSE_ORDERED:
 156         fd->have_ordered = true;
 157         if (OMP_CLAUSE_ORDERED_EXPR (t))
 158           fd->ordered = tree_to_shwi (OMP_CLAUSE_ORDERED_EXPR (t));
 159         break;
 160       case OMP_CLAUSE_SCHEDULE:
 161         gcc_assert (!distribute && !taskloop);
 162         fd->sched_kind
 163           = (enum omp_clause_schedule_kind)
 164             (OMP_CLAUSE_SCHEDULE_KIND (t) & OMP_CLAUSE_SCHEDULE_MASK);
 165         fd->sched_modifiers = (OMP_CLAUSE_SCHEDULE_KIND (t)
 166                                & ~OMP_CLAUSE_SCHEDULE_MASK);
 167         fd->chunk_size = OMP_CLAUSE_SCHEDULE_CHUNK_EXPR (t);
 168         fd->simd_schedule = OMP_CLAUSE_SCHEDULE_SIMD (t);
 169         break;
 170       case OMP_CLAUSE_DIST_SCHEDULE:
 171         gcc_assert (distribute);
 172         fd->chunk_size = OMP_CLAUSE_DIST_SCHEDULE_CHUNK_EXPR (t);
 173         break;
 174       case OMP_CLAUSE_COLLAPSE:
 175         fd->collapse = tree_to_shwi (OMP_CLAUSE_COLLAPSE_EXPR (t));
 176         if (fd->collapse > 1)
 177           {
 178             collapse_iter = &OMP_CLAUSE_COLLAPSE_ITERVAR (t);
 179             collapse_count = &OMP_CLAUSE_COLLAPSE_COUNT (t);
 180           }
 181         break;
 182       case OMP_CLAUSE_TILE:
 183         fd->tiling = OMP_CLAUSE_TILE_LIST (t);
 184         fd->collapse = list_length (fd->tiling);
 185         gcc_assert (fd->collapse);
 186         collapse_iter = &OMP_CLAUSE_TILE_ITERVAR (t);
 187         collapse_count = &OMP_CLAUSE_TILE_COUNT (t);
 188         break;
 189       default:
 190         break;
 191       }
 192
 193   if (fd->collapse > 1 || fd->tiling)
 194     fd->loops = loops;
 195   else
 196     fd->loops = &fd->loop;
 197
 198   if (fd->ordered && fd->collapse == 1 && loops != NULL)
 199     {
 200       fd->loops = loops;
 201       iterv = NULL_TREE;
 202       countv = NULL_TREE;
 203       collapse_iter = &iterv;
 204       collapse_count = &countv;
 205     }
 206
 207   /* FIXME: for now map schedule(auto) to schedule(static).
 208      There should be analysis to determine whether all iterations
 209      are approximately the same amount of work (then schedule(static)
 210      is best) or if it varies (then schedule(dynamic,N) is better).  */
 211   if (fd->sched_kind == OMP_CLAUSE_SCHEDULE_AUTO)
 212     {
 213       fd->sched_kind = OMP_CLAUSE_SCHEDULE_STATIC;
 214       gcc_assert (fd->chunk_size == NULL);
 215     }
 216   gcc_assert ((fd->collapse == 1 && !fd->tiling) || collapse_iter != NULL);
 217   if (taskloop)
 218     fd->sched_kind = OMP_CLAUSE_SCHEDULE_RUNTIME;
 219   if (fd->sched_kind == OMP_CLAUSE_SCHEDULE_RUNTIME)
 220     gcc_assert (fd->chunk_size == NULL);
 221   else if (fd->chunk_size == NULL)
 222     {
 223       /* We only need to compute a default chunk size for ordered
 224          static loops and dynamic loops.  */
 225       if (fd->sched_kind != OMP_CLAUSE_SCHEDULE_STATIC
 226           || fd->have_ordered)
 227         fd->chunk_size = (fd->sched_kind == OMP_CLAUSE_SCHEDULE_STATIC)
 228                          ? integer_zero_node : integer_one_node;
 229     }
 230
 231   int cnt = fd->ordered ? fd->ordered : fd->collapse;
 232   for (i = 0; i < cnt; i++)
 233     {
 234       if (i == 0
 235           && fd->collapse == 1
 236           && !fd->tiling
 237           && (fd->ordered == 0 || loops == NULL))
 238         loop = &fd->loop;
 239       else if (loops != NULL)
 240         loop = loops + i;
 241       else
 242         loop = &dummy_loop;
 243
 244       loop->v = gimple_omp_for_index (for_stmt, i);
 245       gcc_assert (SSA_VAR_P (loop->v));
 246       gcc_assert (TREE_CODE (TREE_TYPE (loop->v)) == INTEGER_TYPE
 247                   || TREE_CODE (TREE_TYPE (loop->v)) == POINTER_TYPE);
 248       var = TREE_CODE (loop->v) == SSA_NAME ? SSA_NAME_VAR (loop->v) : loop->v;
 249       loop->n1 = gimple_omp_for_initial (for_stmt, i);
 250
 251       loop->cond_code = gimple_omp_for_cond (for_stmt, i);
 252       loop->n2 = gimple_omp_for_final (for_stmt, i);
 253       gcc_assert (loop->cond_code != NE_EXPR);
 254       omp_adjust_for_condition (loc, &loop->cond_code, &loop->n2);
 255
 256       t = gimple_omp_for_incr (for_stmt, i);
 257       gcc_assert (TREE_OPERAND (t, 0) == var);
 258       loop->step = omp_get_for_step_from_incr (loc, t);
 259
 260       if (simd
 261           || (fd->sched_kind == OMP_CLAUSE_SCHEDULE_STATIC
 262               && !fd->have_ordered))
 263         {
 264           if (fd->collapse == 1 && !fd->tiling)
 265             iter_type = TREE_TYPE (loop->v);
 266           else if (i == 0
 267                    || TYPE_PRECISION (iter_type)
 268                       < TYPE_PRECISION (TREE_TYPE (loop->v)))
 269             iter_type
 270               = build_nonstandard_integer_type
 271                   (TYPE_PRECISION (TREE_TYPE (loop->v)), 1);
 272         }
 273       else if (iter_type != long_long_unsigned_type_node)
 274         {
 275           if (POINTER_TYPE_P (TREE_TYPE (loop->v)))
 276             iter_type = long_long_unsigned_type_node;
 277           else if (TYPE_UNSIGNED (TREE_TYPE (loop->v))
 278                    && TYPE_PRECISION (TREE_TYPE (loop->v))
 279                       >= TYPE_PRECISION (iter_type))
 280             {
 281               tree n;
 282
 283               if (loop->cond_code == LT_EXPR)
 284                 n = fold_build2_loc (loc,
 285                                  PLUS_EXPR, TREE_TYPE (loop->v),
 286                                  loop->n2, loop->step);
 287               else
 288                 n = loop->n1;
 289               if (TREE_CODE (n) != INTEGER_CST
 290                   || tree_int_cst_lt (TYPE_MAX_VALUE (iter_type), n))
 291                 iter_type = long_long_unsigned_type_node;
 292             }
 293           else if (TYPE_PRECISION (TREE_TYPE (loop->v))
 294                    > TYPE_PRECISION (iter_type))
 295             {
 296               tree n1, n2;
 297
 298               if (loop->cond_code == LT_EXPR)
 299                 {
 300                   n1 = loop->n1;
 301                   n2 = fold_build2_loc (loc,
 302                                     PLUS_EXPR, TREE_TYPE (loop->v),
 303                                     loop->n2, loop->step);
 304                 }
 305               else
 306                 {
 307                   n1 = fold_build2_loc (loc,
 308                                     MINUS_EXPR, TREE_TYPE (loop->v),
 309                                     loop->n2, loop->step);
 310                   n2 = loop->n1;
 311                 }
 312               if (TREE_CODE (n1) != INTEGER_CST
 313                   || TREE_CODE (n2) != INTEGER_CST
 314                   || !tree_int_cst_lt (TYPE_MIN_VALUE (iter_type), n1)
 315                   || !tree_int_cst_lt (n2, TYPE_MAX_VALUE (iter_type)))
 316                 iter_type = long_long_unsigned_type_node;
 317             }
 318         }
 319
 320       if (i >= fd->collapse)
 321         continue;
 322
 323       if (collapse_count && *collapse_count == NULL)
 324         {
 325           t = fold_binary (loop->cond_code, boolean_type_node,
 326                            fold_convert (TREE_TYPE (loop->v), loop->n1),
 327                            fold_convert (TREE_TYPE (loop->v), loop->n2));
 328           if (t && integer_zerop (t))
 329             count = build_zero_cst (long_long_unsigned_type_node);
 330           else if ((i == 0 || count != NULL_TREE)
 331                    && TREE_CODE (TREE_TYPE (loop->v)) == INTEGER_TYPE
 332                    && TREE_CONSTANT (loop->n1)
 333                    && TREE_CONSTANT (loop->n2)
 334                    && TREE_CODE (loop->step) == INTEGER_CST)
 335             {
 336               tree itype = TREE_TYPE (loop->v);
 337
 338               if (POINTER_TYPE_P (itype))
 339                 itype = signed_type_for (itype);
 340               t = build_int_cst (itype, (loop->cond_code == LT_EXPR ? -1 : 1));
 341               t = fold_build2_loc (loc,
 342                                PLUS_EXPR, itype,
 343                                fold_convert_loc (loc, itype, loop->step), t);
 344               t = fold_build2_loc (loc, PLUS_EXPR, itype, t,
 345                                fold_convert_loc (loc, itype, loop->n2));
 346               t = fold_build2_loc (loc, MINUS_EXPR, itype, t,
 347                                fold_convert_loc (loc, itype, loop->n1));
 348               if (TYPE_UNSIGNED (itype) && loop->cond_code == GT_EXPR)
 349                 t = fold_build2_loc (loc, TRUNC_DIV_EXPR, itype,
 350                                  fold_build1_loc (loc, NEGATE_EXPR, itype, t),
 351                                  fold_build1_loc (loc, NEGATE_EXPR, itype,
 352                                               fold_convert_loc (loc, itype,
 353                                                                 loop->step)));
 354               else
 355                 t = fold_build2_loc (loc, TRUNC_DIV_EXPR, itype, t,
 356                                  fold_convert_loc (loc, itype, loop->step));
 357               t = fold_convert_loc (loc, long_long_unsigned_type_node, t);
 358               if (count != NULL_TREE)
 359                 count = fold_build2_loc (loc,
 360                                      MULT_EXPR, long_long_unsigned_type_node,
 361                                      count, t);
 362               else
 363                 count = t;
 364               if (TREE_CODE (count) != INTEGER_CST)
 365                 count = NULL_TREE;
 366             }
 367           else if (count && !integer_zerop (count))
 368             count = NULL_TREE;
 369         }
 370     }
 371
 372   if (count
 373       && !simd
 374       && (fd->sched_kind != OMP_CLAUSE_SCHEDULE_STATIC
 375           || fd->have_ordered))
 376     {
 377       if (!tree_int_cst_lt (count, TYPE_MAX_VALUE (long_integer_type_node)))
 378         iter_type = long_long_unsigned_type_node;
 379       else
 380         iter_type = long_integer_type_node;
 381     }
 382   else if (collapse_iter && *collapse_iter != NULL)
 383     iter_type = TREE_TYPE (*collapse_iter);
 384   fd->iter_type = iter_type;
 385   if (collapse_iter && *collapse_iter == NULL)
 386     *collapse_iter = create_tmp_var (iter_type, ".iter");
 387   if (collapse_count && *collapse_count == NULL)
 388     {
 389       if (count)
 390         *collapse_count = fold_convert_loc (loc, iter_type, count);
 391       else
 392         *collapse_count = create_tmp_var (iter_type, ".count");
 393     }
 394
 395   if (fd->collapse > 1 || fd->tiling || (fd->ordered && loops))
 396     {
 397       fd->loop.v = *collapse_iter;
 398       fd->loop.n1 = build_int_cst (TREE_TYPE (fd->loop.v), 0);
 399       fd->loop.n2 = *collapse_count;
 400       fd->loop.step = build_int_cst (TREE_TYPE (fd->loop.v), 1);
 401       fd->loop.cond_code = LT_EXPR;
 402     }
 403   else if (loops)
 404     loops[0] = fd->loop;
 405 }
 406
 407 /* Build a call to GOMP_barrier.  */
 408
 409 gimple *
 410 omp_build_barrier (tree lhs)
 411 {
 412   tree fndecl = builtin_decl_explicit (lhs ? BUILT_IN_GOMP_BARRIER_CANCEL
 413                                            : BUILT_IN_GOMP_BARRIER);
 414   gcall *g = gimple_build_call (fndecl, 0);
 415   if (lhs)
 416     gimple_call_set_lhs (g, lhs);
 417   return g;
 418 }
 419
 420 /* Return maximum possible vectorization factor for the target.  */
 421
 422 poly_uint64
 423 omp_max_vf (void)
 424 {
 425   if (!optimize
 426       || optimize_debug
 427       || !flag_tree_loop_optimize
 428       || (!flag_tree_loop_vectorize
 429           && global_options_set.x_flag_tree_loop_vectorize))
 430     return 1;
 431
 432   auto_vector_sizes sizes;
 433   targetm.vectorize.autovectorize_vector_sizes (&sizes);
 434   if (!sizes.is_empty ())
 435     {
 436       poly_uint64 vf = 0;
 437       for (unsigned int i = 0; i < sizes.length (); ++i)
 438         vf = ordered_max (vf, sizes[i]);
 439       return vf;
 440     }
 441
 442   machine_mode vqimode = targetm.vectorize.preferred_simd_mode (QImode);
 443   if (GET_MODE_CLASS (vqimode) == MODE_VECTOR_INT)
 444     return GET_MODE_NUNITS (vqimode);
 445
 446   return 1;
 447 }
 448
 449 /* Return maximum SIMT width if offloading may target SIMT hardware.  */
 450
 451 int
 452 omp_max_simt_vf (void)
 453 {
 454   if (!optimize)
 455     return 0;
 456   if (ENABLE_OFFLOADING)
 457     for (const char *c = getenv ("OFFLOAD_TARGET_NAMES"); c;)
 458       {
 459         if (!strncmp (c, "nvptx", strlen ("nvptx")))
 460           return 32;
 461         else if ((c = strchr (c, ',')))
 462           c++;
 463       }
 464   return 0;
 465 }
 466
 467 /* Encode an oacc launch argument.  This matches the GOMP_LAUNCH_PACK
 468    macro on gomp-constants.h.  We do not check for overflow.  */
 469
 470 tree
 471 oacc_launch_pack (unsigned code, tree device, unsigned op)
 472 {
 473   tree res;
 474
 475   res = build_int_cst (unsigned_type_node, GOMP_LAUNCH_PACK (code, 0, op));
 476   if (device)
 477     {
 478       device = fold_build2 (LSHIFT_EXPR, unsigned_type_node,
 479                             device, build_int_cst (unsigned_type_node,
 480                                                    GOMP_LAUNCH_DEVICE_SHIFT));
 481       res = fold_build2 (BIT_IOR_EXPR, unsigned_type_node, res, device);
 482     }
 483   return res;
 484 }
 485
 486 /* FIXME: What is the following comment for? */
 487 /* Look for compute grid dimension clauses and convert to an attribute
 488    attached to FN.  This permits the target-side code to (a) massage
 489    the dimensions, (b) emit that data and (c) optimize.  Non-constant
 490    dimensions are pushed onto ARGS.
 491
 492    The attribute value is a TREE_LIST.  A set of dimensions is
 493    represented as a list of INTEGER_CST.  Those that are runtime
 494    exprs are represented as an INTEGER_CST of zero.
 495
 496    TODO: Normally the attribute will just contain a single such list.  If
 497    however it contains a list of lists, this will represent the use of
 498    device_type.  Each member of the outer list is an assoc list of
 499    dimensions, keyed by the device type.  The first entry will be the
 500    default.  Well, that's the plan.  */
 501
 502 /* Replace any existing oacc fn attribute with updated dimensions.  */
 503
 504 void
 505 oacc_replace_fn_attrib (tree fn, tree dims)
 506 {
 507   tree ident = get_identifier (OACC_FN_ATTRIB);
 508   tree attribs = DECL_ATTRIBUTES (fn);
 509
 510   /* If we happen to be present as the first attrib, drop it.  */
 511   if (attribs && TREE_PURPOSE (attribs) == ident)
 512     attribs = TREE_CHAIN (attribs);
 513   DECL_ATTRIBUTES (fn) = tree_cons (ident, dims, attribs);
 514 }
 515
 516 /* Scan CLAUSES for launch dimensions and attach them to the oacc
 517    function attribute.  Push any that are non-constant onto the ARGS
 518    list, along with an appropriate GOMP_LAUNCH_DIM tag.  */
 519
 520 void
 521 oacc_set_fn_attrib (tree fn, tree clauses, vec<tree> *args)
 522 {
 523   /* Must match GOMP_DIM ordering.  */
 524   static const omp_clause_code ids[]
 525     = { OMP_CLAUSE_NUM_GANGS, OMP_CLAUSE_NUM_WORKERS,
 526         OMP_CLAUSE_VECTOR_LENGTH };
 527   unsigned ix;
 528   tree dims[GOMP_DIM_MAX];
 529
 530   tree attr = NULL_TREE;
 531   unsigned non_const = 0;
 532
 533   for (ix = GOMP_DIM_MAX; ix--;)
 534     {
 535       tree clause = omp_find_clause (clauses, ids[ix]);
 536       tree dim = NULL_TREE;
 537
 538       if (clause)
 539         dim = OMP_CLAUSE_EXPR (clause, ids[ix]);
 540       dims[ix] = dim;
 541       if (dim && TREE_CODE (dim) != INTEGER_CST)
 542         {
 543           dim = integer_zero_node;
 544           non_const |= GOMP_DIM_MASK (ix);
 545         }
 546       attr = tree_cons (NULL_TREE, dim, attr);
 547     }
 548
 549   oacc_replace_fn_attrib (fn, attr);
 550
 551   if (non_const)
 552     {
 553       /* Push a dynamic argument set.  */
 554       args->safe_push (oacc_launch_pack (GOMP_LAUNCH_DIM,
 555                                          NULL_TREE, non_const));
 556       for (unsigned ix = 0; ix != GOMP_DIM_MAX; ix++)
 557         if (non_const & GOMP_DIM_MASK (ix))
 558           args->safe_push (dims[ix]);
 559     }
 560 }
 561
 562 /*  Process the routine's dimension clauess to generate an attribute
 563     value.  Issue diagnostics as appropriate.  We default to SEQ
 564     (OpenACC 2.5 clarifies this). All dimensions have a size of zero
 565     (dynamic).  TREE_PURPOSE is set to indicate whether that dimension
 566     can have a loop partitioned on it.  non-zero indicates
 567     yes, zero indicates no.  By construction once a non-zero has been
 568     reached, further inner dimensions must also be non-zero.  We set
 569     TREE_VALUE to zero for the dimensions that may be partitioned and
 570     1 for the other ones -- if a loop is (erroneously) spawned at
 571     an outer level, we don't want to try and partition it.  */
 572
 573 tree
 574 oacc_build_routine_dims (tree clauses)
 575 {
 576   /* Must match GOMP_DIM ordering.  */
 577   static const omp_clause_code ids[]
 578     = {OMP_CLAUSE_GANG, OMP_CLAUSE_WORKER, OMP_CLAUSE_VECTOR, OMP_CLAUSE_SEQ};
 579   int ix;
 580   int level = -1;
 581
 582   for (; clauses; clauses = OMP_CLAUSE_CHAIN (clauses))
 583     for (ix = GOMP_DIM_MAX + 1; ix--;)
 584       if (OMP_CLAUSE_CODE (clauses) == ids[ix])
 585         {
 586           if (level >= 0)
 587             error_at (OMP_CLAUSE_LOCATION (clauses),
 588                       "multiple loop axes specified for routine");
 589           level = ix;
 590           break;
 591         }
 592
 593   /* Default to SEQ.  */
 594   if (level < 0)
 595     level = GOMP_DIM_MAX;
 596
 597   tree dims = NULL_TREE;
 598
 599   for (ix = GOMP_DIM_MAX; ix--;)
 600     dims = tree_cons (build_int_cst (boolean_type_node, ix >= level),
 601                       build_int_cst (integer_type_node, ix < level), dims);
 602
 603   return dims;
 604 }
 605
 606 /* Retrieve the oacc function attrib and return it.  Non-oacc
 607    functions will return NULL.  */
 608
 609 tree
 610 oacc_get_fn_attrib (tree fn)
 611 {
 612   return lookup_attribute (OACC_FN_ATTRIB, DECL_ATTRIBUTES (fn));
 613 }
 614
 615 /* Extract an oacc execution dimension from FN.  FN must be an
 616    offloaded function or routine that has already had its execution
 617    dimensions lowered to the target-specific values.  */
 618
 619 int
 620 oacc_get_fn_dim_size (tree fn, int axis)
 621 {
 622   tree attrs = oacc_get_fn_attrib (fn);
 623
 624   gcc_assert (axis < GOMP_DIM_MAX);
 625
 626   tree dims = TREE_VALUE (attrs);
 627   while (axis--)
 628     dims = TREE_CHAIN (dims);
 629
 630   int size = TREE_INT_CST_LOW (TREE_VALUE (dims));
 631
 632   return size;
 633 }
 634
 635 /* Extract the dimension axis from an IFN_GOACC_DIM_POS or
 636    IFN_GOACC_DIM_SIZE call.  */
 637
 638 int
 639 oacc_get_ifn_dim_arg (const gimple *stmt)
 640 {
 641   gcc_checking_assert (gimple_call_internal_fn (stmt) == IFN_GOACC_DIM_SIZE
 642                        || gimple_call_internal_fn (stmt) == IFN_GOACC_DIM_POS);
 643   tree arg = gimple_call_arg (stmt, 0);
 644   HOST_WIDE_INT axis = TREE_INT_CST_LOW (arg);
 645
 646   gcc_checking_assert (axis >= 0 && axis < GOMP_DIM_MAX);
 647   return (int) axis;
 648 }