gcc/cp/cp-gimplify.c

   1 /* C++-specific tree lowering bits; see also c-gimplify.c and tree-gimple.c.
   2
   3    Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
   4    Free Software Foundation, Inc.
   5    Contributed by Jason Merrill <jason@redhat.com>
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it under
  10 the terms of the GNU General Public License as published by the Free
  11 Software Foundation; either version 3, or (at your option) any later
  12 version.
  13
  14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "coretypes.h"
  26 #include "tm.h"
  27 #include "tree.h"
  28 #include "cp-tree.h"
  29 #include "c-common.h"
  30 #include "toplev.h"
  31 #include "tree-iterator.h"
  32 #include "gimple.h"
  33 #include "hashtab.h"
  34 #include "pointer-set.h"
  35 #include "flags.h"
  36
  37 /* Local declarations.  */
  38
  39 enum bc_t { bc_break = 0, bc_continue = 1 };
  40
  41 /* Stack of labels which are targets for "break" or "continue",
  42    linked through TREE_CHAIN.  */
  43 static tree bc_label[2];
  44
  45 /* Begin a scope which can be exited by a break or continue statement.  BC
  46    indicates which.
  47
  48    Just creates a label and pushes it into the current context.  */
  49
  50 static tree
  51 begin_bc_block (enum bc_t bc)
  52 {
  53   tree label = create_artificial_label ();
  54   TREE_CHAIN (label) = bc_label[bc];
  55   bc_label[bc] = label;
  56   return label;
  57 }
  58
  59 /* Finish a scope which can be exited by a break or continue statement.
  60    LABEL was returned from the most recent call to begin_bc_block.  BODY is
  61    an expression for the contents of the scope.
  62
  63    If we saw a break (or continue) in the scope, append a LABEL_EXPR to
  64    body.  Otherwise, just forget the label.  */
  65
  66 static gimple_seq
  67 finish_bc_block (enum bc_t bc, tree label, gimple_seq body)
  68 {
  69   gcc_assert (label == bc_label[bc]);
  70
  71   if (TREE_USED (label))
  72     {
  73       gimple_seq_add_stmt (&body, gimple_build_label (label));
  74     }
  75
  76   bc_label[bc] = TREE_CHAIN (label);
  77   TREE_CHAIN (label) = NULL_TREE;
  78   return body;
  79 }
  80
  81 /* Get the LABEL_EXPR to represent a break or continue statement
  82    in the current block scope.  BC indicates which.  */
  83
  84 static tree
  85 get_bc_label (enum bc_t bc)
  86 {
  87   tree label = bc_label[bc];
  88
  89   if (label == NULL_TREE)
  90     {
  91       if (bc == bc_break)
  92         error ("break statement not within loop or switch");
  93       else
  94         error ("continue statement not within loop or switch");
  95
  96       return NULL_TREE;
  97     }
  98
  99   /* Mark the label used for finish_bc_block.  */
 100   TREE_USED (label) = 1;
 101   return label;
 102 }
 103
 104 /* Genericize a TRY_BLOCK.  */
 105
 106 static void
 107 genericize_try_block (tree *stmt_p)
 108 {
 109   tree body = TRY_STMTS (*stmt_p);
 110   tree cleanup = TRY_HANDLERS (*stmt_p);
 111
 112   *stmt_p = build2 (TRY_CATCH_EXPR, void_type_node, body, cleanup);
 113 }
 114
 115 /* Genericize a HANDLER by converting to a CATCH_EXPR.  */
 116
 117 static void
 118 genericize_catch_block (tree *stmt_p)
 119 {
 120   tree type = HANDLER_TYPE (*stmt_p);
 121   tree body = HANDLER_BODY (*stmt_p);
 122
 123   /* FIXME should the caught type go in TREE_TYPE?  */
 124   *stmt_p = build2 (CATCH_EXPR, void_type_node, type, body);
 125 }
 126
 127 /* A terser interface for building a representation of an exception
 128    specification.  */
 129
 130 static tree
 131 build_gimple_eh_filter_tree (tree body, tree allowed, tree failure)
 132 {
 133   tree t;
 134
 135   /* FIXME should the allowed types go in TREE_TYPE?  */
 136   t = build2 (EH_FILTER_EXPR, void_type_node, allowed, NULL_TREE);
 137   append_to_statement_list (failure, &EH_FILTER_FAILURE (t));
 138
 139   t = build2 (TRY_CATCH_EXPR, void_type_node, NULL_TREE, t);
 140   append_to_statement_list (body, &TREE_OPERAND (t, 0));
 141
 142   return t;
 143 }
 144
 145 /* Genericize an EH_SPEC_BLOCK by converting it to a
 146    TRY_CATCH_EXPR/EH_FILTER_EXPR pair.  */
 147
 148 static void
 149 genericize_eh_spec_block (tree *stmt_p)
 150 {
 151   tree body = EH_SPEC_STMTS (*stmt_p);
 152   tree allowed = EH_SPEC_RAISES (*stmt_p);
 153   tree failure = build_call_n (call_unexpected_node, 1, build_exc_ptr ());
 154
 155   *stmt_p = build_gimple_eh_filter_tree (body, allowed, failure);
 156 }
 157
 158 /* Genericize an IF_STMT by turning it into a COND_EXPR.  */
 159
 160 static void
 161 gimplify_if_stmt (tree *stmt_p)
 162 {
 163   tree stmt, cond, then_, else_;
 164   location_t locus = EXPR_LOCATION (*stmt_p);
 165
 166   stmt = *stmt_p;
 167   cond = IF_COND (stmt);
 168   then_ = THEN_CLAUSE (stmt);
 169   else_ = ELSE_CLAUSE (stmt);
 170
 171   if (!then_)
 172     then_ = build_empty_stmt ();
 173   if (!else_)
 174     else_ = build_empty_stmt ();
 175
 176   if (integer_nonzerop (cond) && !TREE_SIDE_EFFECTS (else_))
 177     stmt = then_;
 178   else if (integer_zerop (cond) && !TREE_SIDE_EFFECTS (then_))
 179     stmt = else_;
 180   else
 181     stmt = build3 (COND_EXPR, void_type_node, cond, then_, else_);
 182   if (CAN_HAVE_LOCATION_P (stmt) && !EXPR_HAS_LOCATION (stmt))
 183     SET_EXPR_LOCATION (stmt, locus);
 184   *stmt_p = stmt;
 185 }
 186
 187 /* Build a generic representation of one of the C loop forms.  COND is the
 188    loop condition or NULL_TREE.  BODY is the (possibly compound) statement
 189    controlled by the loop.  INCR is the increment expression of a for-loop,
 190    or NULL_TREE.  COND_IS_FIRST indicates whether the condition is
 191    evaluated before the loop body as in while and for loops, or after the
 192    loop body as in do-while loops.  */
 193
 194 static gimple_seq
 195 gimplify_cp_loop (tree cond, tree body, tree incr, bool cond_is_first)
 196 {
 197   gimple top, entry, stmt;
 198   gimple_seq stmt_list, body_seq, incr_seq, exit_seq;
 199   tree cont_block, break_block;
 200   location_t stmt_locus;
 201
 202   stmt_locus = input_location;
 203   stmt_list = NULL;
 204   body_seq = NULL;
 205   incr_seq = NULL;
 206   exit_seq = NULL;
 207   entry = NULL;
 208
 209   break_block = begin_bc_block (bc_break);
 210   cont_block = begin_bc_block (bc_continue);
 211
 212   /* If condition is zero don't generate a loop construct.  */
 213   if (cond && integer_zerop (cond))
 214     {
 215       top = NULL;
 216       if (cond_is_first)
 217         {
 218           stmt = gimple_build_goto (get_bc_label (bc_break));
 219           gimple_set_location (stmt, stmt_locus);
 220           gimple_seq_add_stmt (&stmt_list, stmt);
 221         }
 222     }
 223   else
 224     {
 225       /* If we use a LOOP_EXPR here, we have to feed the whole thing
 226          back through the main gimplifier to lower it.  Given that we
 227          have to gimplify the loop body NOW so that we can resolve
 228          break/continue stmts, seems easier to just expand to gotos.  */
 229       top = gimple_build_label (create_artificial_label ());
 230
 231       /* If we have an exit condition, then we build an IF with gotos either
 232          out of the loop, or to the top of it.  If there's no exit condition,
 233          then we just build a jump back to the top.  */
 234       if (cond && !integer_nonzerop (cond))
 235         {
 236           if (cond != error_mark_node)
 237             {
 238               gimplify_expr (&cond, &exit_seq, NULL, is_gimple_val, fb_rvalue);
 239               stmt = gimple_build_cond (NE_EXPR, cond,
 240                                         build_int_cst (TREE_TYPE (cond), 0),
 241                                         gimple_label_label (top),
 242                                         get_bc_label (bc_break));
 243               gimple_seq_add_stmt (&exit_seq, stmt);
 244             }
 245
 246           if (cond_is_first)
 247             {
 248               if (incr)
 249                 {
 250                   entry = gimple_build_label (create_artificial_label ());
 251                   stmt = gimple_build_goto (gimple_label_label (entry));
 252                 }
 253               else
 254                 stmt = gimple_build_goto (get_bc_label (bc_continue));
 255               gimple_set_location (stmt, stmt_locus);
 256               gimple_seq_add_stmt (&stmt_list, stmt);
 257             }
 258         }
 259       else
 260         {
 261           stmt = gimple_build_goto (gimple_label_label (top));
 262           gimple_seq_add_stmt (&exit_seq, stmt);
 263         }
 264     }
 265
 266   gimplify_stmt (&body, &body_seq);
 267   gimplify_stmt (&incr, &incr_seq);
 268
 269   body_seq = finish_bc_block (bc_continue, cont_block, body_seq);
 270
 271   gimple_seq_add_stmt (&stmt_list, top);
 272   gimple_seq_add_seq (&stmt_list, body_seq);
 273   gimple_seq_add_seq (&stmt_list, incr_seq);
 274   gimple_seq_add_stmt (&stmt_list, entry);
 275   gimple_seq_add_seq (&stmt_list, exit_seq);
 276
 277   annotate_all_with_location (stmt_list, stmt_locus);
 278
 279   return finish_bc_block (bc_break, break_block, stmt_list);
 280 }
 281
 282 /* Gimplify a FOR_STMT node.  Move the stuff in the for-init-stmt into the
 283    prequeue and hand off to gimplify_cp_loop.  */
 284
 285 static void
 286 gimplify_for_stmt (tree *stmt_p, gimple_seq *pre_p)
 287 {
 288   tree stmt = *stmt_p;
 289
 290   if (FOR_INIT_STMT (stmt))
 291     gimplify_and_add (FOR_INIT_STMT (stmt), pre_p);
 292
 293   gimple_seq_add_seq (pre_p,
 294                       gimplify_cp_loop (FOR_COND (stmt), FOR_BODY (stmt),
 295                                         FOR_EXPR (stmt), 1));
 296   *stmt_p = NULL_TREE;
 297 }
 298
 299 /* Gimplify a WHILE_STMT node.  */
 300
 301 static void
 302 gimplify_while_stmt (tree *stmt_p, gimple_seq *pre_p)
 303 {
 304   tree stmt = *stmt_p;
 305   gimple_seq_add_seq (pre_p,
 306                       gimplify_cp_loop (WHILE_COND (stmt), WHILE_BODY (stmt),
 307                                         NULL_TREE, 1));
 308   *stmt_p = NULL_TREE;
 309 }
 310
 311 /* Gimplify a DO_STMT node.  */
 312
 313 static void
 314 gimplify_do_stmt (tree *stmt_p, gimple_seq *pre_p)
 315 {
 316   tree stmt = *stmt_p;
 317   gimple_seq_add_seq (pre_p,
 318                       gimplify_cp_loop (DO_COND (stmt), DO_BODY (stmt),
 319                                         NULL_TREE, 0));
 320   *stmt_p = NULL_TREE;
 321 }
 322
 323 /* Genericize a SWITCH_STMT by turning it into a SWITCH_EXPR.  */
 324
 325 static void
 326 gimplify_switch_stmt (tree *stmt_p, gimple_seq *pre_p)
 327 {
 328   tree stmt = *stmt_p;
 329   tree break_block, body, t;
 330   location_t stmt_locus = input_location;
 331   gimple_seq seq = NULL;
 332
 333   break_block = begin_bc_block (bc_break);
 334
 335   body = SWITCH_STMT_BODY (stmt);
 336   if (!body)
 337     body = build_empty_stmt ();
 338
 339   t = build3 (SWITCH_EXPR, SWITCH_STMT_TYPE (stmt),
 340               SWITCH_STMT_COND (stmt), body, NULL_TREE);
 341   SET_EXPR_LOCATION (t, stmt_locus);
 342   gimplify_and_add (t, &seq);
 343
 344   seq = finish_bc_block (bc_break, break_block, seq);
 345   gimple_seq_add_seq (pre_p, seq);
 346   *stmt_p = NULL_TREE;
 347 }
 348
 349 /* Hook into the middle of gimplifying an OMP_FOR node.  This is required
 350    in order to properly gimplify CONTINUE statements.  Here we merely
 351    manage the continue stack; the rest of the job is performed by the
 352    regular gimplifier.  */
 353
 354 static enum gimplify_status
 355 cp_gimplify_omp_for (tree *expr_p, gimple_seq *pre_p)
 356 {
 357   tree for_stmt = *expr_p;
 358   tree cont_block;
 359   gimple stmt;
 360   gimple_seq seq = NULL;
 361
 362   /* Protect ourselves from recursion.  */
 363   if (OMP_FOR_GIMPLIFYING_P (for_stmt))
 364     return GS_UNHANDLED;
 365   OMP_FOR_GIMPLIFYING_P (for_stmt) = 1;
 366
 367   /* Note that while technically the continue label is enabled too soon
 368      here, we should have already diagnosed invalid continues nested within
 369      statement expressions within the INIT, COND, or INCR expressions.  */
 370   cont_block = begin_bc_block (bc_continue);
 371
 372   gimplify_and_add (for_stmt, &seq);
 373   stmt = gimple_seq_last_stmt (seq);
 374   if (gimple_code (stmt) == GIMPLE_OMP_FOR)
 375     gimple_omp_set_body (stmt, finish_bc_block (bc_continue, cont_block,
 376                                                 gimple_omp_body (stmt)));
 377   else
 378     seq = finish_bc_block (bc_continue, cont_block, seq);
 379   gimple_seq_add_seq (pre_p, seq);
 380
 381   OMP_FOR_GIMPLIFYING_P (for_stmt) = 0;
 382
 383   return GS_ALL_DONE;
 384 }
 385
 386 /*  Gimplify an EXPR_STMT node.  */
 387
 388 static void
 389 gimplify_expr_stmt (tree *stmt_p)
 390 {
 391   tree stmt = EXPR_STMT_EXPR (*stmt_p);
 392
 393   if (stmt == error_mark_node)
 394     stmt = NULL;
 395
 396   /* Gimplification of a statement expression will nullify the
 397      statement if all its side effects are moved to *PRE_P and *POST_P.
 398
 399      In this case we will not want to emit the gimplified statement.
 400      However, we may still want to emit a warning, so we do that before
 401      gimplification.  */
 402   if (stmt && warn_unused_value)
 403     {
 404       if (!TREE_SIDE_EFFECTS (stmt))
 405         {
 406           if (!IS_EMPTY_STMT (stmt)
 407               && !VOID_TYPE_P (TREE_TYPE (stmt))
 408               && !TREE_NO_WARNING (stmt))
 409             warning (OPT_Wunused_value, "statement with no effect");
 410         }
 411       else
 412         warn_if_unused_value (stmt, input_location);
 413     }
 414
 415   if (stmt == NULL_TREE)
 416     stmt = alloc_stmt_list ();
 417
 418   *stmt_p = stmt;
 419 }
 420
 421 /* Gimplify initialization from an AGGR_INIT_EXPR.  */
 422
 423 static void
 424 cp_gimplify_init_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
 425 {
 426   tree from = TREE_OPERAND (*expr_p, 1);
 427   tree to = TREE_OPERAND (*expr_p, 0);
 428   tree t;
 429   tree slot = NULL_TREE;
 430
 431   /* What about code that pulls out the temp and uses it elsewhere?  I
 432      think that such code never uses the TARGET_EXPR as an initializer.  If
 433      I'm wrong, we'll abort because the temp won't have any RTL.  In that
 434      case, I guess we'll need to replace references somehow.  */
 435   if (TREE_CODE (from) == TARGET_EXPR)
 436     {
 437       slot = TARGET_EXPR_SLOT (from);
 438       from = TARGET_EXPR_INITIAL (from);
 439     }
 440
 441   /* Look through any COMPOUND_EXPRs, since build_compound_expr pushes them
 442      inside the TARGET_EXPR.  */
 443   for (t = from; t; )
 444     {
 445       tree sub = TREE_CODE (t) == COMPOUND_EXPR ? TREE_OPERAND (t, 0) : t;
 446
 447       /* If we are initializing from an AGGR_INIT_EXPR, drop the INIT_EXPR and
 448          replace the slot operand with our target.
 449
 450          Should we add a target parm to gimplify_expr instead?  No, as in this
 451          case we want to replace the INIT_EXPR.  */
 452       if (TREE_CODE (sub) == AGGR_INIT_EXPR)
 453         {
 454           gimplify_expr (&to, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
 455           AGGR_INIT_EXPR_SLOT (sub) = to;
 456           *expr_p = from;
 457
 458           /* The initialization is now a side-effect, so the container can
 459              become void.  */
 460           if (from != sub)
 461             TREE_TYPE (from) = void_type_node;
 462         }
 463       else if (TREE_CODE (sub) == INIT_EXPR
 464                && TREE_OPERAND (sub, 0) == slot)
 465         {
 466           /* An INIT_EXPR under TARGET_EXPR created by build_value_init,
 467              will be followed by an AGGR_INIT_EXPR.  */
 468           gimplify_expr (&to, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
 469           TREE_OPERAND (sub, 0) = to;
 470         }
 471
 472       if (t == sub)
 473         break;
 474       else
 475         t = TREE_OPERAND (t, 1);
 476     }
 477
 478 }
 479
 480 /* Gimplify a MUST_NOT_THROW_EXPR.  */
 481
 482 static enum gimplify_status
 483 gimplify_must_not_throw_expr (tree *expr_p, gimple_seq *pre_p)
 484 {
 485   tree stmt = *expr_p;
 486   tree temp = voidify_wrapper_expr (stmt, NULL);
 487   tree body = TREE_OPERAND (stmt, 0);
 488
 489   stmt = build_gimple_eh_filter_tree (body, NULL_TREE,
 490                                       build_call_n (terminate_node, 0));
 491
 492   gimplify_and_add (stmt, pre_p);
 493   if (temp)
 494     {
 495       *expr_p = temp;
 496       return GS_OK;
 497     }
 498
 499   *expr_p = NULL;
 500   return GS_ALL_DONE;
 501 }
 502
 503 /* Do C++-specific gimplification.  Args are as for gimplify_expr.  */
 504
 505 int
 506 cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
 507 {
 508   int saved_stmts_are_full_exprs_p = 0;
 509   enum tree_code code = TREE_CODE (*expr_p);
 510   enum gimplify_status ret;
 511   tree block = NULL;
 512   VEC(gimple, heap) *bind_expr_stack = NULL;
 513
 514   if (STATEMENT_CODE_P (code))
 515     {
 516       saved_stmts_are_full_exprs_p = stmts_are_full_exprs_p ();
 517       current_stmt_tree ()->stmts_are_full_exprs_p
 518         = STMT_IS_FULL_EXPR_P (*expr_p);
 519     }
 520
 521   switch (code)
 522     {
 523     case PTRMEM_CST:
 524       *expr_p = cplus_expand_constant (*expr_p);
 525       ret = GS_OK;
 526       break;
 527
 528     case AGGR_INIT_EXPR:
 529       simplify_aggr_init_expr (expr_p);
 530       ret = GS_OK;
 531       break;
 532
 533     case THROW_EXPR:
 534       /* FIXME communicate throw type to back end, probably by moving
 535          THROW_EXPR into ../tree.def.  */
 536       *expr_p = TREE_OPERAND (*expr_p, 0);
 537       ret = GS_OK;
 538       break;
 539
 540     case MUST_NOT_THROW_EXPR:
 541       ret = gimplify_must_not_throw_expr (expr_p, pre_p);
 542       break;
 543
 544       /* We used to do this for MODIFY_EXPR as well, but that's unsafe; the
 545          LHS of an assignment might also be involved in the RHS, as in bug
 546          25979.  */
 547     case INIT_EXPR:
 548       cp_gimplify_init_expr (expr_p, pre_p, post_p);
 549       ret = GS_OK;
 550       break;
 551
 552     case EMPTY_CLASS_EXPR:
 553       /* We create an empty CONSTRUCTOR with RECORD_TYPE.  */
 554       *expr_p = build_constructor (TREE_TYPE (*expr_p), NULL);
 555       ret = GS_OK;
 556       break;
 557
 558     case BASELINK:
 559       *expr_p = BASELINK_FUNCTIONS (*expr_p);
 560       ret = GS_OK;
 561       break;
 562
 563     case TRY_BLOCK:
 564       genericize_try_block (expr_p);
 565       ret = GS_OK;
 566       break;
 567
 568     case HANDLER:
 569       genericize_catch_block (expr_p);
 570       ret = GS_OK;
 571       break;
 572
 573     case EH_SPEC_BLOCK:
 574       genericize_eh_spec_block (expr_p);
 575       ret = GS_OK;
 576       break;
 577
 578     case USING_STMT:
 579       /* Get the innermost inclosing GIMPLE_BIND that has a non NULL
 580          BLOCK, and append an IMPORTED_DECL to its
 581          BLOCK_VARS chained list.  */
 582
 583       bind_expr_stack = gimple_bind_expr_stack ();
 584       if (bind_expr_stack)
 585         {
 586           int i;
 587           for (i = VEC_length (gimple, bind_expr_stack) - 1; i >= 0; i--)
 588             if ((block = gimple_bind_block (VEC_index (gimple,
 589                                                        bind_expr_stack,
 590                                                        i))))
 591               break;
 592         }
 593       if (block)
 594         {
 595           tree using_directive;
 596           gcc_assert (TREE_OPERAND (*expr_p,0)
 597                       && NAMESPACE_DECL_CHECK (TREE_OPERAND (*expr_p, 0)));
 598
 599           using_directive = make_node (IMPORTED_DECL);
 600           TREE_TYPE (using_directive) = void_type_node;
 601
 602           IMPORTED_DECL_ASSOCIATED_DECL (using_directive)
 603             = TREE_OPERAND (*expr_p, 0);
 604           DECL_NAME (using_directive)
 605             = DECL_NAME (TREE_OPERAND (*expr_p, 0));
 606           TREE_CHAIN (using_directive) = BLOCK_VARS (block);
 607           BLOCK_VARS (block) = using_directive;
 608         }
 609       /* The USING_STMT won't appear in GIMPLE.  */
 610       *expr_p = NULL;
 611       ret = GS_ALL_DONE;
 612       break;
 613
 614     case IF_STMT:
 615       gimplify_if_stmt (expr_p);
 616       ret = GS_OK;
 617       break;
 618
 619     case FOR_STMT:
 620       gimplify_for_stmt (expr_p, pre_p);
 621       ret = GS_OK;
 622       break;
 623
 624     case WHILE_STMT:
 625       gimplify_while_stmt (expr_p, pre_p);
 626       ret = GS_OK;
 627       break;
 628
 629     case DO_STMT:
 630       gimplify_do_stmt (expr_p, pre_p);
 631       ret = GS_OK;
 632       break;
 633
 634     case SWITCH_STMT:
 635       gimplify_switch_stmt (expr_p, pre_p);
 636       ret = GS_OK;
 637       break;
 638
 639     case OMP_FOR:
 640       ret = cp_gimplify_omp_for (expr_p, pre_p);
 641       break;
 642
 643     case CONTINUE_STMT:
 644       gimple_seq_add_stmt (pre_p, gimple_build_predict (PRED_CONTINUE, NOT_TAKEN));
 645       gimple_seq_add_stmt (pre_p, gimple_build_goto (get_bc_label (bc_continue)));
 646       *expr_p = NULL_TREE;
 647       ret = GS_ALL_DONE;
 648       break;
 649
 650     case BREAK_STMT:
 651       gimple_seq_add_stmt (pre_p, gimple_build_goto (get_bc_label (bc_break)));
 652       *expr_p = NULL_TREE;
 653       ret = GS_ALL_DONE;
 654       break;
 655
 656     case EXPR_STMT:
 657       gimplify_expr_stmt (expr_p);
 658       ret = GS_OK;
 659       break;
 660
 661     case UNARY_PLUS_EXPR:
 662       {
 663         tree arg = TREE_OPERAND (*expr_p, 0);
 664         tree type = TREE_TYPE (*expr_p);
 665         *expr_p = (TREE_TYPE (arg) != type) ? fold_convert (type, arg)
 666                                             : arg;
 667         ret = GS_OK;
 668       }
 669       break;
 670
 671     default:
 672       ret = c_gimplify_expr (expr_p, pre_p, post_p);
 673       break;
 674     }
 675
 676   /* Restore saved state.  */
 677   if (STATEMENT_CODE_P (code))
 678     current_stmt_tree ()->stmts_are_full_exprs_p
 679       = saved_stmts_are_full_exprs_p;
 680
 681   return ret;
 682 }
 683
 684 static inline bool
 685 is_invisiref_parm (const_tree t)
 686 {
 687   return ((TREE_CODE (t) == PARM_DECL || TREE_CODE (t) == RESULT_DECL)
 688           && DECL_BY_REFERENCE (t));
 689 }
 690
 691 /* Return true if the uid in both int tree maps are equal.  */
 692
 693 int
 694 cxx_int_tree_map_eq (const void *va, const void *vb)
 695 {
 696   const struct cxx_int_tree_map *a = (const struct cxx_int_tree_map *) va;
 697   const struct cxx_int_tree_map *b = (const struct cxx_int_tree_map *) vb;
 698   return (a->uid == b->uid);
 699 }
 700
 701 /* Hash a UID in a cxx_int_tree_map.  */
 702
 703 unsigned int
 704 cxx_int_tree_map_hash (const void *item)
 705 {
 706   return ((const struct cxx_int_tree_map *)item)->uid;
 707 }
 708
 709 /* Perform any pre-gimplification lowering of C++ front end trees to
 710    GENERIC.  */
 711
 712 static tree
 713 cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
 714 {
 715   tree stmt = *stmt_p;
 716   struct pointer_set_t *p_set = (struct pointer_set_t*) data;
 717
 718   if (is_invisiref_parm (stmt)
 719       /* Don't dereference parms in a thunk, pass the references through. */
 720       && !(DECL_THUNK_P (current_function_decl)
 721            && TREE_CODE (stmt) == PARM_DECL))
 722     {
 723       *stmt_p = convert_from_reference (stmt);
 724       *walk_subtrees = 0;
 725       return NULL;
 726     }
 727
 728   /* Map block scope extern declarations to visible declarations with the
 729      same name and type in outer scopes if any.  */
 730   if (cp_function_chain->extern_decl_map
 731       && (TREE_CODE (stmt) == FUNCTION_DECL || TREE_CODE (stmt) == VAR_DECL)
 732       && DECL_EXTERNAL (stmt))
 733     {
 734       struct cxx_int_tree_map *h, in;
 735       in.uid = DECL_UID (stmt);
 736       h = (struct cxx_int_tree_map *)
 737           htab_find_with_hash (cp_function_chain->extern_decl_map,
 738                                &in, in.uid);
 739       if (h)
 740         {
 741           *stmt_p = h->to;
 742           *walk_subtrees = 0;
 743           return NULL;
 744         }
 745     }
 746
 747   /* Other than invisiref parms, don't walk the same tree twice.  */
 748   if (pointer_set_contains (p_set, stmt))
 749     {
 750       *walk_subtrees = 0;
 751       return NULL_TREE;
 752     }
 753
 754   if (TREE_CODE (stmt) == ADDR_EXPR
 755       && is_invisiref_parm (TREE_OPERAND (stmt, 0)))
 756     {
 757       *stmt_p = convert (TREE_TYPE (stmt), TREE_OPERAND (stmt, 0));
 758       *walk_subtrees = 0;
 759     }
 760   else if (TREE_CODE (stmt) == RETURN_EXPR
 761            && TREE_OPERAND (stmt, 0)
 762            && is_invisiref_parm (TREE_OPERAND (stmt, 0)))
 763     /* Don't dereference an invisiref RESULT_DECL inside a RETURN_EXPR.  */
 764     *walk_subtrees = 0;
 765   else if (TREE_CODE (stmt) == OMP_CLAUSE)
 766     switch (OMP_CLAUSE_CODE (stmt))
 767       {
 768       case OMP_CLAUSE_LASTPRIVATE:
 769         /* Don't dereference an invisiref in OpenMP clauses.  */
 770         if (is_invisiref_parm (OMP_CLAUSE_DECL (stmt)))
 771           {
 772             *walk_subtrees = 0;
 773             if (OMP_CLAUSE_LASTPRIVATE_STMT (stmt))
 774               cp_walk_tree (&OMP_CLAUSE_LASTPRIVATE_STMT (stmt),
 775                             cp_genericize_r, p_set, NULL);
 776           }
 777         break;
 778       case OMP_CLAUSE_PRIVATE:
 779       case OMP_CLAUSE_SHARED:
 780       case OMP_CLAUSE_FIRSTPRIVATE:
 781       case OMP_CLAUSE_COPYIN:
 782       case OMP_CLAUSE_COPYPRIVATE:
 783         /* Don't dereference an invisiref in OpenMP clauses.  */
 784         if (is_invisiref_parm (OMP_CLAUSE_DECL (stmt)))
 785           *walk_subtrees = 0;
 786         break;
 787       case OMP_CLAUSE_REDUCTION:
 788         gcc_assert (!is_invisiref_parm (OMP_CLAUSE_DECL (stmt)));
 789         break;
 790       default:
 791         break;
 792       }
 793   else if (IS_TYPE_OR_DECL_P (stmt))
 794     *walk_subtrees = 0;
 795
 796   /* Due to the way voidify_wrapper_expr is written, we don't get a chance
 797      to lower this construct before scanning it, so we need to lower these
 798      before doing anything else.  */
 799   else if (TREE_CODE (stmt) == CLEANUP_STMT)
 800     *stmt_p = build2 (CLEANUP_EH_ONLY (stmt) ? TRY_CATCH_EXPR
 801                                              : TRY_FINALLY_EXPR,
 802                       void_type_node,
 803                       CLEANUP_BODY (stmt),
 804                       CLEANUP_EXPR (stmt));
 805
 806   pointer_set_insert (p_set, *stmt_p);
 807
 808   return NULL;
 809 }
 810
 811 void
 812 cp_genericize (tree fndecl)
 813 {
 814   tree t;
 815   struct pointer_set_t *p_set;
 816
 817   /* Fix up the types of parms passed by invisible reference.  */
 818   for (t = DECL_ARGUMENTS (fndecl); t; t = TREE_CHAIN (t))
 819     if (TREE_ADDRESSABLE (TREE_TYPE (t)))
 820       {
 821         /* If a function's arguments are copied to create a thunk,
 822            then DECL_BY_REFERENCE will be set -- but the type of the
 823            argument will be a pointer type, so we will never get
 824            here.  */
 825         gcc_assert (!DECL_BY_REFERENCE (t));
 826         gcc_assert (DECL_ARG_TYPE (t) != TREE_TYPE (t));
 827         TREE_TYPE (t) = DECL_ARG_TYPE (t);
 828         DECL_BY_REFERENCE (t) = 1;
 829         TREE_ADDRESSABLE (t) = 0;
 830         relayout_decl (t);
 831       }
 832
 833   /* Do the same for the return value.  */
 834   if (TREE_ADDRESSABLE (TREE_TYPE (DECL_RESULT (fndecl))))
 835     {
 836       t = DECL_RESULT (fndecl);
 837       TREE_TYPE (t) = build_reference_type (TREE_TYPE (t));
 838       DECL_BY_REFERENCE (t) = 1;
 839       TREE_ADDRESSABLE (t) = 0;
 840       relayout_decl (t);
 841     }
 842
 843   /* If we're a clone, the body is already GIMPLE.  */
 844   if (DECL_CLONED_FUNCTION_P (fndecl))
 845     return;
 846
 847   /* We do want to see every occurrence of the parms, so we can't just use
 848      walk_tree's hash functionality.  */
 849   p_set = pointer_set_create ();
 850   cp_walk_tree (&DECL_SAVED_TREE (fndecl), cp_genericize_r, p_set, NULL);
 851   pointer_set_destroy (p_set);
 852
 853   /* Do everything else.  */
 854   c_genericize (fndecl);
 855
 856   gcc_assert (bc_label[bc_break] == NULL);
 857   gcc_assert (bc_label[bc_continue] == NULL);
 858 }
 859 \f
 860 /* Build code to apply FN to each member of ARG1 and ARG2.  FN may be
 861    NULL if there is in fact nothing to do.  ARG2 may be null if FN
 862    actually only takes one argument.  */
 863
 864 static tree
 865 cxx_omp_clause_apply_fn (tree fn, tree arg1, tree arg2)
 866 {
 867   tree defparm, parm, t;
 868   int i = 0;
 869   int nargs;
 870   tree *argarray;
 871
 872   if (fn == NULL)
 873     return NULL;
 874
 875   nargs = list_length (DECL_ARGUMENTS (fn));
 876   argarray = (tree *) alloca (nargs * sizeof (tree));
 877
 878   defparm = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (fn)));
 879   if (arg2)
 880     defparm = TREE_CHAIN (defparm);
 881
 882   if (TREE_CODE (TREE_TYPE (arg1)) == ARRAY_TYPE)
 883     {
 884       tree inner_type = TREE_TYPE (arg1);
 885       tree start1, end1, p1;
 886       tree start2 = NULL, p2 = NULL;
 887       tree ret = NULL, lab;
 888
 889       start1 = arg1;
 890       start2 = arg2;
 891       do
 892         {
 893           inner_type = TREE_TYPE (inner_type);
 894           start1 = build4 (ARRAY_REF, inner_type, start1,
 895                            size_zero_node, NULL, NULL);
 896           if (arg2)
 897             start2 = build4 (ARRAY_REF, inner_type, start2,
 898                              size_zero_node, NULL, NULL);
 899         }
 900       while (TREE_CODE (inner_type) == ARRAY_TYPE);
 901       start1 = build_fold_addr_expr (start1);
 902       if (arg2)
 903         start2 = build_fold_addr_expr (start2);
 904
 905       end1 = TYPE_SIZE_UNIT (TREE_TYPE (arg1));
 906       end1 = build2 (POINTER_PLUS_EXPR, TREE_TYPE (start1), start1, end1);
 907
 908       p1 = create_tmp_var (TREE_TYPE (start1), NULL);
 909       t = build2 (MODIFY_EXPR, TREE_TYPE (p1), p1, start1);
 910       append_to_statement_list (t, &ret);
 911
 912       if (arg2)
 913         {
 914           p2 = create_tmp_var (TREE_TYPE (start2), NULL);
 915           t = build2 (MODIFY_EXPR, TREE_TYPE (p2), p2, start2);
 916           append_to_statement_list (t, &ret);
 917         }
 918
 919       lab = create_artificial_label ();
 920       t = build1 (LABEL_EXPR, void_type_node, lab);
 921       append_to_statement_list (t, &ret);
 922
 923       argarray[i++] = p1;
 924       if (arg2)
 925         argarray[i++] = p2;
 926       /* Handle default arguments.  */
 927       for (parm = defparm; parm && parm != void_list_node;
 928            parm = TREE_CHAIN (parm), i++)
 929         argarray[i] = convert_default_arg (TREE_VALUE (parm),
 930                                            TREE_PURPOSE (parm), fn, i);
 931       t = build_call_a (fn, i, argarray);
 932       t = fold_convert (void_type_node, t);
 933       t = fold_build_cleanup_point_expr (TREE_TYPE (t), t);
 934       append_to_statement_list (t, &ret);
 935
 936       t = TYPE_SIZE_UNIT (inner_type);
 937       t = build2 (POINTER_PLUS_EXPR, TREE_TYPE (p1), p1, t);
 938       t = build2 (MODIFY_EXPR, TREE_TYPE (p1), p1, t);
 939       append_to_statement_list (t, &ret);
 940
 941       if (arg2)
 942         {
 943           t = TYPE_SIZE_UNIT (inner_type);
 944           t = build2 (POINTER_PLUS_EXPR, TREE_TYPE (p2), p2, t);
 945           t = build2 (MODIFY_EXPR, TREE_TYPE (p2), p2, t);
 946           append_to_statement_list (t, &ret);
 947         }
 948
 949       t = build2 (NE_EXPR, boolean_type_node, p1, end1);
 950       t = build3 (COND_EXPR, void_type_node, t, build_and_jump (&lab), NULL);
 951       append_to_statement_list (t, &ret);
 952
 953       return ret;
 954     }
 955   else
 956     {
 957       argarray[i++] = build_fold_addr_expr (arg1);
 958       if (arg2)
 959         argarray[i++] = build_fold_addr_expr (arg2);
 960       /* Handle default arguments.  */
 961       for (parm = defparm; parm && parm != void_list_node;
 962            parm = TREE_CHAIN (parm), i++)
 963         argarray[i] = convert_default_arg (TREE_VALUE (parm),
 964                                            TREE_PURPOSE (parm),
 965                                            fn, i);
 966       t = build_call_a (fn, i, argarray);
 967       t = fold_convert (void_type_node, t);
 968       return fold_build_cleanup_point_expr (TREE_TYPE (t), t);
 969     }
 970 }
 971
 972 /* Return code to initialize DECL with its default constructor, or
 973    NULL if there's nothing to do.  */
 974
 975 tree
 976 cxx_omp_clause_default_ctor (tree clause, tree decl,
 977                              tree outer ATTRIBUTE_UNUSED)
 978 {
 979   tree info = CP_OMP_CLAUSE_INFO (clause);
 980   tree ret = NULL;
 981
 982   if (info)
 983     ret = cxx_omp_clause_apply_fn (TREE_VEC_ELT (info, 0), decl, NULL);
 984
 985   return ret;
 986 }
 987
 988 /* Return code to initialize DST with a copy constructor from SRC.  */
 989
 990 tree
 991 cxx_omp_clause_copy_ctor (tree clause, tree dst, tree src)
 992 {
 993   tree info = CP_OMP_CLAUSE_INFO (clause);
 994   tree ret = NULL;
 995
 996   if (info)
 997     ret = cxx_omp_clause_apply_fn (TREE_VEC_ELT (info, 0), dst, src);
 998   if (ret == NULL)
 999     ret = build2 (MODIFY_EXPR, TREE_TYPE (dst), dst, src);
1000
1001   return ret;
1002 }
1003
1004 /* Similarly, except use an assignment operator instead.  */
1005
1006 tree
1007 cxx_omp_clause_assign_op (tree clause, tree dst, tree src)
1008 {
1009   tree info = CP_OMP_CLAUSE_INFO (clause);
1010   tree ret = NULL;
1011
1012   if (info)
1013     ret = cxx_omp_clause_apply_fn (TREE_VEC_ELT (info, 2), dst, src);
1014   if (ret == NULL)
1015     ret = build2 (MODIFY_EXPR, TREE_TYPE (dst), dst, src);
1016
1017   return ret;
1018 }
1019
1020 /* Return code to destroy DECL.  */
1021
1022 tree
1023 cxx_omp_clause_dtor (tree clause, tree decl)
1024 {
1025   tree info = CP_OMP_CLAUSE_INFO (clause);
1026   tree ret = NULL;
1027
1028   if (info)
1029     ret = cxx_omp_clause_apply_fn (TREE_VEC_ELT (info, 1), decl, NULL);
1030
1031   return ret;
1032 }
1033
1034 /* True if OpenMP should privatize what this DECL points to rather
1035    than the DECL itself.  */
1036
1037 bool
1038 cxx_omp_privatize_by_reference (const_tree decl)
1039 {
1040   return is_invisiref_parm (decl);
1041 }
1042
1043 /* True if OpenMP sharing attribute of DECL is predetermined.  */
1044
1045 enum omp_clause_default_kind
1046 cxx_omp_predetermined_sharing (tree decl)
1047 {
1048   tree type;
1049
1050   /* Static data members are predetermined as shared.  */
1051   if (TREE_STATIC (decl))
1052     {
1053       tree ctx = CP_DECL_CONTEXT (decl);
1054       if (TYPE_P (ctx) && MAYBE_CLASS_TYPE_P (ctx))
1055         return OMP_CLAUSE_DEFAULT_SHARED;
1056     }
1057
1058   type = TREE_TYPE (decl);
1059   if (TREE_CODE (type) == REFERENCE_TYPE)
1060     {
1061       if (!is_invisiref_parm (decl))
1062         return OMP_CLAUSE_DEFAULT_UNSPECIFIED;
1063       type = TREE_TYPE (type);
1064
1065       if (TREE_CODE (decl) == RESULT_DECL && DECL_NAME (decl))
1066         {
1067           /* NVR doesn't preserve const qualification of the
1068              variable's type.  */
1069           tree outer = outer_curly_brace_block (current_function_decl);
1070           tree var;
1071
1072           if (outer)
1073             for (var = BLOCK_VARS (outer); var; var = TREE_CHAIN (var))
1074               if (DECL_NAME (decl) == DECL_NAME (var)
1075                   && (TYPE_MAIN_VARIANT (type)
1076                       == TYPE_MAIN_VARIANT (TREE_TYPE (var))))
1077                 {
1078                   if (TYPE_READONLY (TREE_TYPE (var)))
1079                     type = TREE_TYPE (var);
1080                   break;
1081                 }
1082         }
1083     }
1084
1085   if (type == error_mark_node)
1086     return OMP_CLAUSE_DEFAULT_UNSPECIFIED;
1087
1088   /* Variables with const-qualified type having no mutable member
1089      are predetermined shared.  */
1090   if (TYPE_READONLY (type) && !cp_has_mutable_p (type))
1091     return OMP_CLAUSE_DEFAULT_SHARED;
1092
1093   return OMP_CLAUSE_DEFAULT_UNSPECIFIED;
1094 }
1095
1096 /* Finalize an implicitly determined clause.  */
1097
1098 void
1099 cxx_omp_finish_clause (tree c)
1100 {
1101   tree decl, inner_type;
1102   bool make_shared = false;
1103
1104   if (OMP_CLAUSE_CODE (c) != OMP_CLAUSE_FIRSTPRIVATE)
1105     return;
1106
1107   decl = OMP_CLAUSE_DECL (c);
1108   decl = require_complete_type (decl);
1109   inner_type = TREE_TYPE (decl);
1110   if (decl == error_mark_node)
1111     make_shared = true;
1112   else if (TREE_CODE (TREE_TYPE (decl)) == REFERENCE_TYPE)
1113     {
1114       if (is_invisiref_parm (decl))
1115         inner_type = TREE_TYPE (inner_type);
1116       else
1117         {
1118           error ("%qE implicitly determined as %<firstprivate%> has reference type",
1119                  decl);
1120           make_shared = true;
1121         }
1122     }
1123
1124   /* We're interested in the base element, not arrays.  */
1125   while (TREE_CODE (inner_type) == ARRAY_TYPE)
1126     inner_type = TREE_TYPE (inner_type);
1127
1128   /* Check for special function availability by building a call to one.
1129      Save the results, because later we won't be in the right context
1130      for making these queries.  */
1131   if (!make_shared
1132       && CLASS_TYPE_P (inner_type)
1133       && cxx_omp_create_clause_info (c, inner_type, false, true, false))
1134     make_shared = true;
1135
1136   if (make_shared)
1137     OMP_CLAUSE_CODE (c) = OMP_CLAUSE_SHARED;
1138 }