gcc/c-omp.c

   1 /* This file contains routines to construct GNU OpenMP constructs,
   2    called from parsing in the C and C++ front ends.
   3
   4    Copyright (C) 2005, 2007, 2008 Free Software Foundation, Inc.
   5    Contributed by Richard Henderson <rth@redhat.com>,
   6                   Diego Novillo <dnovillo@redhat.com>.
   7
   8 This file is part of GCC.
   9
  10 GCC is free software; you can redistribute it and/or modify it under
  11 the terms of the GNU General Public License as published by the Free
  12 Software Foundation; either version 3, or (at your option) any later
  13 version.
  14
  15 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  16 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18 for more details.
  19
  20 You should have received a copy of the GNU General Public License
  21 along with GCC; see the file COPYING3.  If not see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "tm.h"
  28 #include "tree.h"
  29 #include "function.h"
  30 #include "c-common.h"
  31 #include "toplev.h"
  32 #include "gimple.h"
  33 #include "bitmap.h"
  34 #include "langhooks.h"
  35
  36
  37 /* Complete a #pragma omp master construct.  STMT is the structured-block
  38    that follows the pragma.  */
  39
  40 tree
  41 c_finish_omp_master (tree stmt)
  42 {
  43   return add_stmt (build1 (OMP_MASTER, void_type_node, stmt));
  44 }
  45
  46 /* Complete a #pragma omp critical construct.  STMT is the structured-block
  47    that follows the pragma, NAME is the identifier in the pragma, or null
  48    if it was omitted.  */
  49
  50 tree
  51 c_finish_omp_critical (tree body, tree name)
  52 {
  53   tree stmt = make_node (OMP_CRITICAL);
  54   TREE_TYPE (stmt) = void_type_node;
  55   OMP_CRITICAL_BODY (stmt) = body;
  56   OMP_CRITICAL_NAME (stmt) = name;
  57   return add_stmt (stmt);
  58 }
  59
  60 /* Complete a #pragma omp ordered construct.  STMT is the structured-block
  61    that follows the pragma.  */
  62
  63 tree
  64 c_finish_omp_ordered (tree stmt)
  65 {
  66   return add_stmt (build1 (OMP_ORDERED, void_type_node, stmt));
  67 }
  68
  69
  70 /* Complete a #pragma omp barrier construct.  */
  71
  72 void
  73 c_finish_omp_barrier (void)
  74 {
  75   tree x;
  76
  77   x = built_in_decls[BUILT_IN_GOMP_BARRIER];
  78   x = build_call_expr (x, 0);
  79   add_stmt (x);
  80 }
  81
  82
  83 /* Complete a #pragma omp taskwait construct.  */
  84
  85 void
  86 c_finish_omp_taskwait (void)
  87 {
  88   tree x;
  89
  90   x = built_in_decls[BUILT_IN_GOMP_TASKWAIT];
  91   x = build_call_expr (x, 0);
  92   add_stmt (x);
  93 }
  94
  95
  96 /* Complete a #pragma omp atomic construct.  The expression to be
  97    implemented atomically is LHS code= RHS.  The value returned is
  98    either error_mark_node (if the construct was erroneous) or an
  99    OMP_ATOMIC node which should be added to the current statement tree
 100    with add_stmt.  */
 101
 102 tree
 103 c_finish_omp_atomic (enum tree_code code, tree lhs, tree rhs)
 104 {
 105   tree x, type, addr;
 106
 107   if (lhs == error_mark_node || rhs == error_mark_node)
 108     return error_mark_node;
 109
 110   /* ??? According to one reading of the OpenMP spec, complex type are
 111      supported, but there are no atomic stores for any architecture.
 112      But at least icc 9.0 doesn't support complex types here either.
 113      And lets not even talk about vector types...  */
 114   type = TREE_TYPE (lhs);
 115   if (!INTEGRAL_TYPE_P (type)
 116       && !POINTER_TYPE_P (type)
 117       && !SCALAR_FLOAT_TYPE_P (type))
 118     {
 119       error ("invalid expression type for %<#pragma omp atomic%>");
 120       return error_mark_node;
 121     }
 122
 123   /* ??? Validate that rhs does not overlap lhs.  */
 124
 125   /* Take and save the address of the lhs.  From then on we'll reference it
 126      via indirection.  */
 127   addr = build_unary_op (input_location, ADDR_EXPR, lhs, 0);
 128   if (addr == error_mark_node)
 129     return error_mark_node;
 130   addr = save_expr (addr);
 131   if (TREE_CODE (addr) != SAVE_EXPR
 132       && (TREE_CODE (addr) != ADDR_EXPR
 133           || TREE_CODE (TREE_OPERAND (addr, 0)) != VAR_DECL))
 134     {
 135       /* Make sure LHS is simple enough so that goa_lhs_expr_p can recognize
 136          it even after unsharing function body.  */
 137       tree var = create_tmp_var_raw (TREE_TYPE (addr), NULL);
 138       addr = build4 (TARGET_EXPR, TREE_TYPE (addr), var, addr, NULL, NULL);
 139     }
 140   lhs = build_indirect_ref (input_location, addr, NULL);
 141
 142   /* There are lots of warnings, errors, and conversions that need to happen
 143      in the course of interpreting a statement.  Use the normal mechanisms
 144      to do this, and then take it apart again.  */
 145   x = build_modify_expr (input_location, lhs, code, rhs);
 146   if (x == error_mark_node)
 147     return error_mark_node;
 148   gcc_assert (TREE_CODE (x) == MODIFY_EXPR);
 149   rhs = TREE_OPERAND (x, 1);
 150
 151   /* Punt the actual generation of atomic operations to common code.  */
 152   return build2 (OMP_ATOMIC, void_type_node, addr, rhs);
 153 }
 154
 155
 156 /* Complete a #pragma omp flush construct.  We don't do anything with the
 157    variable list that the syntax allows.  */
 158
 159 void
 160 c_finish_omp_flush (void)
 161 {
 162   tree x;
 163
 164   x = built_in_decls[BUILT_IN_SYNCHRONIZE];
 165   x = build_call_expr (x, 0);
 166   add_stmt (x);
 167 }
 168
 169
 170 /* Check and canonicalize #pragma omp for increment expression.
 171    Helper function for c_finish_omp_for.  */
 172
 173 static tree
 174 check_omp_for_incr_expr (tree exp, tree decl)
 175 {
 176   tree t;
 177
 178   if (!INTEGRAL_TYPE_P (TREE_TYPE (exp))
 179       || TYPE_PRECISION (TREE_TYPE (exp)) < TYPE_PRECISION (TREE_TYPE (decl)))
 180     return error_mark_node;
 181
 182   if (exp == decl)
 183     return build_int_cst (TREE_TYPE (exp), 0);
 184
 185   switch (TREE_CODE (exp))
 186     {
 187     CASE_CONVERT:
 188       t = check_omp_for_incr_expr (TREE_OPERAND (exp, 0), decl);
 189       if (t != error_mark_node)
 190         return fold_convert (TREE_TYPE (exp), t);
 191       break;
 192     case MINUS_EXPR:
 193       t = check_omp_for_incr_expr (TREE_OPERAND (exp, 0), decl);
 194       if (t != error_mark_node)
 195         return fold_build2 (MINUS_EXPR, TREE_TYPE (exp), t, TREE_OPERAND (exp, 1));
 196       break;
 197     case PLUS_EXPR:
 198       t = check_omp_for_incr_expr (TREE_OPERAND (exp, 0), decl);
 199       if (t != error_mark_node)
 200         return fold_build2 (PLUS_EXPR, TREE_TYPE (exp), t, TREE_OPERAND (exp, 1));
 201       t = check_omp_for_incr_expr (TREE_OPERAND (exp, 1), decl);
 202       if (t != error_mark_node)
 203         return fold_build2 (PLUS_EXPR, TREE_TYPE (exp), TREE_OPERAND (exp, 0), t);
 204       break;
 205     default:
 206       break;
 207     }
 208
 209   return error_mark_node;
 210 }
 211
 212 /* Validate and emit code for the OpenMP directive #pragma omp for.
 213    DECLV is a vector of iteration variables, for each collapsed loop.
 214    INITV, CONDV and INCRV are vectors containing initialization
 215    expressions, controlling predicates and increment expressions.
 216    BODY is the body of the loop and PRE_BODY statements that go before
 217    the loop.  */
 218
 219 tree
 220 c_finish_omp_for (location_t locus, tree declv, tree initv, tree condv,
 221                   tree incrv, tree body, tree pre_body)
 222 {
 223   location_t elocus;
 224   bool fail = false;
 225   int i;
 226
 227   gcc_assert (TREE_VEC_LENGTH (declv) == TREE_VEC_LENGTH (initv));
 228   gcc_assert (TREE_VEC_LENGTH (declv) == TREE_VEC_LENGTH (condv));
 229   gcc_assert (TREE_VEC_LENGTH (declv) == TREE_VEC_LENGTH (incrv));
 230   for (i = 0; i < TREE_VEC_LENGTH (declv); i++)
 231     {
 232       tree decl = TREE_VEC_ELT (declv, i);
 233       tree init = TREE_VEC_ELT (initv, i);
 234       tree cond = TREE_VEC_ELT (condv, i);
 235       tree incr = TREE_VEC_ELT (incrv, i);
 236
 237       elocus = locus;
 238       if (EXPR_HAS_LOCATION (init))
 239         elocus = EXPR_LOCATION (init);
 240
 241       /* Validate the iteration variable.  */
 242       if (!INTEGRAL_TYPE_P (TREE_TYPE (decl))
 243           && TREE_CODE (TREE_TYPE (decl)) != POINTER_TYPE)
 244         {
 245           error_at (elocus, "invalid type for iteration variable %qE", decl);
 246           fail = true;
 247         }
 248
 249       /* In the case of "for (int i = 0...)", init will be a decl.  It should
 250          have a DECL_INITIAL that we can turn into an assignment.  */
 251       if (init == decl)
 252         {
 253           elocus = DECL_SOURCE_LOCATION (decl);
 254
 255           init = DECL_INITIAL (decl);
 256           if (init == NULL)
 257             {
 258               error_at (elocus, "%qE is not initialized", decl);
 259               init = integer_zero_node;
 260               fail = true;
 261             }
 262
 263           init = build_modify_expr (elocus, decl, NOP_EXPR, init);
 264         }
 265       gcc_assert (TREE_CODE (init) == MODIFY_EXPR);
 266       gcc_assert (TREE_OPERAND (init, 0) == decl);
 267
 268       if (cond == NULL_TREE)
 269         {
 270           error_at (elocus, "missing controlling predicate");
 271           fail = true;
 272         }
 273       else
 274         {
 275           bool cond_ok = false;
 276
 277           if (EXPR_HAS_LOCATION (cond))
 278             elocus = EXPR_LOCATION (cond);
 279
 280           if (TREE_CODE (cond) == LT_EXPR
 281               || TREE_CODE (cond) == LE_EXPR
 282               || TREE_CODE (cond) == GT_EXPR
 283               || TREE_CODE (cond) == GE_EXPR)
 284             {
 285               tree op0 = TREE_OPERAND (cond, 0);
 286               tree op1 = TREE_OPERAND (cond, 1);
 287
 288               /* 2.5.1.  The comparison in the condition is computed in
 289                  the type of DECL, otherwise the behavior is undefined.
 290
 291                  For example:
 292                  long n; int i;
 293                  i < n;
 294
 295                  according to ISO will be evaluated as:
 296                  (long)i < n;
 297
 298                  We want to force:
 299                  i < (int)n;  */
 300               if (TREE_CODE (op0) == NOP_EXPR
 301                   && decl == TREE_OPERAND (op0, 0))
 302                 {
 303                   TREE_OPERAND (cond, 0) = TREE_OPERAND (op0, 0);
 304                   TREE_OPERAND (cond, 1)
 305                     = fold_build1 (NOP_EXPR, TREE_TYPE (decl),
 306                                    TREE_OPERAND (cond, 1));
 307                 }
 308               else if (TREE_CODE (op1) == NOP_EXPR
 309                        && decl == TREE_OPERAND (op1, 0))
 310                 {
 311                   TREE_OPERAND (cond, 1) = TREE_OPERAND (op1, 0);
 312                   TREE_OPERAND (cond, 0)
 313                     = fold_build1 (NOP_EXPR, TREE_TYPE (decl),
 314                                    TREE_OPERAND (cond, 0));
 315                 }
 316
 317               if (decl == TREE_OPERAND (cond, 0))
 318                 cond_ok = true;
 319               else if (decl == TREE_OPERAND (cond, 1))
 320                 {
 321                   TREE_SET_CODE (cond,
 322                                  swap_tree_comparison (TREE_CODE (cond)));
 323                   TREE_OPERAND (cond, 1) = TREE_OPERAND (cond, 0);
 324                   TREE_OPERAND (cond, 0) = decl;
 325                   cond_ok = true;
 326                 }
 327             }
 328
 329           if (!cond_ok)
 330             {
 331               error_at (elocus, "invalid controlling predicate");
 332               fail = true;
 333             }
 334         }
 335
 336       if (incr == NULL_TREE)
 337         {
 338           error_at (elocus, "missing increment expression");
 339           fail = true;
 340         }
 341       else
 342         {
 343           bool incr_ok = false;
 344
 345           if (EXPR_HAS_LOCATION (incr))
 346             elocus = EXPR_LOCATION (incr);
 347
 348           /* Check all the valid increment expressions: v++, v--, ++v, --v,
 349              v = v + incr, v = incr + v and v = v - incr.  */
 350           switch (TREE_CODE (incr))
 351             {
 352             case POSTINCREMENT_EXPR:
 353             case PREINCREMENT_EXPR:
 354             case POSTDECREMENT_EXPR:
 355             case PREDECREMENT_EXPR:
 356               if (TREE_OPERAND (incr, 0) != decl)
 357                 break;
 358
 359               incr_ok = true;
 360               if (POINTER_TYPE_P (TREE_TYPE (decl))
 361                   && TREE_OPERAND (incr, 1))
 362                 {
 363                   tree t = fold_convert (sizetype, TREE_OPERAND (incr, 1));
 364
 365                   if (TREE_CODE (incr) == POSTDECREMENT_EXPR
 366                       || TREE_CODE (incr) == PREDECREMENT_EXPR)
 367                     t = fold_build1 (NEGATE_EXPR, sizetype, t);
 368                   t = build2 (POINTER_PLUS_EXPR, TREE_TYPE (decl), decl, t);
 369                   incr = build2 (MODIFY_EXPR, void_type_node, decl, t);
 370                 }
 371               break;
 372
 373             case MODIFY_EXPR:
 374               if (TREE_OPERAND (incr, 0) != decl)
 375                 break;
 376               if (TREE_OPERAND (incr, 1) == decl)
 377                 break;
 378               if (TREE_CODE (TREE_OPERAND (incr, 1)) == PLUS_EXPR
 379                   && (TREE_OPERAND (TREE_OPERAND (incr, 1), 0) == decl
 380                       || TREE_OPERAND (TREE_OPERAND (incr, 1), 1) == decl))
 381                 incr_ok = true;
 382               else if ((TREE_CODE (TREE_OPERAND (incr, 1)) == MINUS_EXPR
 383                         || (TREE_CODE (TREE_OPERAND (incr, 1))
 384                             == POINTER_PLUS_EXPR))
 385                        && TREE_OPERAND (TREE_OPERAND (incr, 1), 0) == decl)
 386                 incr_ok = true;
 387               else
 388                 {
 389                   tree t = check_omp_for_incr_expr (TREE_OPERAND (incr, 1),
 390                                                     decl);
 391                   if (t != error_mark_node)
 392                     {
 393                       incr_ok = true;
 394                       t = build2 (PLUS_EXPR, TREE_TYPE (decl), decl, t);
 395                       incr = build2 (MODIFY_EXPR, void_type_node, decl, t);
 396                     }
 397                 }
 398               break;
 399
 400             default:
 401               break;
 402             }
 403           if (!incr_ok)
 404             {
 405               error_at (elocus, "invalid increment expression");
 406               fail = true;
 407             }
 408         }
 409
 410       TREE_VEC_ELT (initv, i) = init;
 411       TREE_VEC_ELT (incrv, i) = incr;
 412     }
 413
 414   if (fail)
 415     return NULL;
 416   else
 417     {
 418       tree t = make_node (OMP_FOR);
 419
 420       TREE_TYPE (t) = void_type_node;
 421       OMP_FOR_INIT (t) = initv;
 422       OMP_FOR_COND (t) = condv;
 423       OMP_FOR_INCR (t) = incrv;
 424       OMP_FOR_BODY (t) = body;
 425       OMP_FOR_PRE_BODY (t) = pre_body;
 426
 427       SET_EXPR_LOCATION (t, locus);
 428       return add_stmt (t);
 429     }
 430 }
 431
 432
 433 /* Divide CLAUSES into two lists: those that apply to a parallel construct,
 434    and those that apply to a work-sharing construct.  Place the results in
 435    *PAR_CLAUSES and *WS_CLAUSES respectively.  In addition, add a nowait
 436    clause to the work-sharing list.  */
 437
 438 void
 439 c_split_parallel_clauses (tree clauses, tree *par_clauses, tree *ws_clauses)
 440 {
 441   tree next;
 442
 443   *par_clauses = NULL;
 444   *ws_clauses = build_omp_clause (OMP_CLAUSE_NOWAIT);
 445
 446   for (; clauses ; clauses = next)
 447     {
 448       next = OMP_CLAUSE_CHAIN (clauses);
 449
 450       switch (OMP_CLAUSE_CODE (clauses))
 451         {
 452         case OMP_CLAUSE_PRIVATE:
 453         case OMP_CLAUSE_SHARED:
 454         case OMP_CLAUSE_FIRSTPRIVATE:
 455         case OMP_CLAUSE_LASTPRIVATE:
 456         case OMP_CLAUSE_REDUCTION:
 457         case OMP_CLAUSE_COPYIN:
 458         case OMP_CLAUSE_IF:
 459         case OMP_CLAUSE_NUM_THREADS:
 460         case OMP_CLAUSE_DEFAULT:
 461           OMP_CLAUSE_CHAIN (clauses) = *par_clauses;
 462           *par_clauses = clauses;
 463           break;
 464
 465         case OMP_CLAUSE_SCHEDULE:
 466         case OMP_CLAUSE_ORDERED:
 467         case OMP_CLAUSE_COLLAPSE:
 468           OMP_CLAUSE_CHAIN (clauses) = *ws_clauses;
 469           *ws_clauses = clauses;
 470           break;
 471
 472         default:
 473           gcc_unreachable ();
 474         }
 475     }
 476 }
 477
 478 /* True if OpenMP sharing attribute of DECL is predetermined.  */
 479
 480 enum omp_clause_default_kind
 481 c_omp_predetermined_sharing (tree decl)
 482 {
 483   /* Variables with const-qualified type having no mutable member
 484      are predetermined shared.  */
 485   if (TREE_READONLY (decl))
 486     return OMP_CLAUSE_DEFAULT_SHARED;
 487
 488   return OMP_CLAUSE_DEFAULT_UNSPECIFIED;
 489 }