gcc/c-semantics.c

   1 /* This file contains the definitions and documentation for the common
   2    tree codes used in the GNU C and C++ compilers (see c-common.def
   3    for the standard codes).
   4    Copyright (C) 2000, 2001 Free Software Foundation, Inc.
   5    Written by Benjamin Chelf (chelf@codesourcery.com).
   6
   7 This file is part of GNU CC.
   8
   9 GNU CC is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 2, or (at your option)
  12 any later version.
  13
  14 GNU CC is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GNU CC; see the file COPYING.  If not, write to
  21 the Free Software Foundation, 59 Temple Place - Suite 330,
  22 Boston, MA 02111-1307, USA.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "tree.h"
  27 #include "function.h"
  28 #include "splay-tree.h"
  29 #include "varray.h"
  30 #include "c-common.h"
  31 #include "except.h"
  32 #include "toplev.h"
  33 #include "flags.h"
  34 #include "ggc.h"
  35 #include "rtl.h"
  36 #include "expr.h"
  37 #include "output.h"
  38 #include "timevar.h"
  39
  40 /* If non-NULL, the address of a language-specific function for
  41    expanding statements.  */
  42 void (*lang_expand_stmt) PARAMS ((tree));
  43
  44 /* If non-NULL, the address of a language-specific function for
  45    expanding a DECL_STMT.  After the language-independent cases are
  46    handled, this function will be called.  If this function is not
  47    defined, it is assumed that declarations other than those for
  48    variables and labels do not require any RTL generation.  */
  49 void (*lang_expand_decl_stmt) PARAMS ((tree));
  50
  51 /* Create an empty statement tree rooted at T.  */
  52
  53 void
  54 begin_stmt_tree (t)
  55      tree *t;
  56 {
  57   /* We create a trivial EXPR_STMT so that last_tree is never NULL in
  58      what follows.  We remove the extraneous statement in
  59      finish_stmt_tree.  */
  60   *t = build_nt (EXPR_STMT, void_zero_node);
  61   last_tree = *t;
  62   last_expr_type = NULL_TREE;
  63 }
  64
  65 /* T is a statement.  Add it to the statement-tree.  */
  66
  67 tree
  68 add_stmt (t)
  69      tree t;
  70 {
  71   /* Add T to the statement-tree.  */
  72   TREE_CHAIN (last_tree) = t;
  73   last_tree = t;
  74
  75   /* When we expand a statement-tree, we must know whether or not the
  76      statements are full-expressions.  We record that fact here.  */
  77   STMT_IS_FULL_EXPR_P (last_tree) = stmts_are_full_exprs_p ();
  78
  79   /* Keep track of the number of statements in this function.  */
  80   if (current_function_decl)
  81     ++DECL_NUM_STMTS (current_function_decl);
  82
  83   return t;
  84 }
  85
  86 /* Create a declaration statement for the declaration given by the
  87    DECL.  */
  88
  89 void
  90 add_decl_stmt (decl)
  91      tree decl;
  92 {
  93   tree decl_stmt;
  94
  95   /* We need the type to last until instantiation time.  */
  96   decl_stmt = build_stmt (DECL_STMT, decl);
  97   add_stmt (decl_stmt);
  98 }
  99
 100 /* Add a scope-statement to the statement-tree.  BEGIN_P indicates
 101    whether this statements opens or closes a scope.  PARTIAL_P is true
 102    for a partial scope, i.e, the scope that begins after a label when
 103    an object that needs a cleanup is created.  If BEGIN_P is nonzero,
 104    returns a new TREE_LIST representing the top of the SCOPE_STMT
 105    stack.  The TREE_PURPOSE is the new SCOPE_STMT.  If BEGIN_P is
 106    zero, returns a TREE_LIST whose TREE_VALUE is the new SCOPE_STMT,
 107    and whose TREE_PURPOSE is the matching SCOPE_STMT with
 108    SCOPE_BEGIN_P set.  */
 109
 110 tree
 111 add_scope_stmt (begin_p, partial_p)
 112      int begin_p;
 113      int partial_p;
 114 {
 115   tree *stack_ptr = current_scope_stmt_stack ();
 116   tree ss;
 117   tree top = *stack_ptr;
 118
 119   /* Build the statement.  */
 120   ss = build_stmt (SCOPE_STMT, NULL_TREE);
 121   SCOPE_BEGIN_P (ss) = begin_p;
 122   SCOPE_PARTIAL_P (ss) = partial_p;
 123
 124   /* Keep the scope stack up to date.  */
 125   if (begin_p)
 126     {
 127       top = tree_cons (ss, NULL_TREE, top);
 128       *stack_ptr = top;
 129     }
 130   else
 131     {
 132       TREE_VALUE (top) = ss;
 133       *stack_ptr = TREE_CHAIN (top);
 134     }
 135
 136   /* Add the new statement to the statement-tree.  */
 137   add_stmt (ss);
 138
 139   return top;
 140 }
 141
 142 /* Finish the statement tree rooted at T.  */
 143
 144 void
 145 finish_stmt_tree (t)
 146      tree *t;
 147 {
 148   tree stmt;
 149
 150   /* Remove the fake extra statement added in begin_stmt_tree.  */
 151   stmt = TREE_CHAIN (*t);
 152   *t = stmt;
 153   last_tree = NULL_TREE;
 154
 155   if (cfun && stmt)
 156     {
 157       /* The line-number recorded in the outermost statement in a function
 158          is the line number of the end of the function.  */
 159       STMT_LINENO (stmt) = lineno;
 160       STMT_LINENO_FOR_FN_P (stmt) = 1;
 161     }
 162 }
 163
 164 /* Build a generic statement based on the given type of node and
 165    arguments. Similar to `build_nt', except that we set
 166    STMT_LINENO to be the current line number.  */
 167 /* ??? This should be obsolete with the lineno_stmt productions
 168    in the grammar.  */
 169
 170 tree
 171 build_stmt VPARAMS ((enum tree_code code, ...))
 172 {
 173 #ifndef ANSI_PROTOTYPES
 174   enum tree_code code;
 175 #endif
 176   va_list p;
 177   register tree t;
 178   register int length;
 179   register int i;
 180
 181   VA_START (p, code);
 182
 183 #ifndef ANSI_PROTOTYPES
 184   code = va_arg (p, enum tree_code);
 185 #endif
 186
 187   t = make_node (code);
 188   length = TREE_CODE_LENGTH (code);
 189   STMT_LINENO (t) = lineno;
 190
 191   for (i = 0; i < length; i++)
 192     TREE_OPERAND (t, i) = va_arg (p, tree);
 193
 194   va_end (p);
 195   return t;
 196 }
 197
 198 /* Some statements, like for-statements or if-statements, require a
 199    condition.  This condition can be a declaration.  If T is such a
 200    declaration it is processed, and an expression appropriate to use
 201    as the condition is returned.  Otherwise, T itself is returned.  */
 202
 203 tree
 204 expand_cond (t)
 205      tree t;
 206 {
 207   if (t && TREE_CODE (t) == TREE_LIST)
 208     {
 209       expand_stmt (TREE_PURPOSE (t));
 210       return TREE_VALUE (t);
 211     }
 212   else
 213     return t;
 214 }
 215
 216 /* Create RTL for the local static variable DECL.  */
 217
 218 void
 219 make_rtl_for_local_static (decl)
 220      tree decl;
 221 {
 222   const char *asmspec = NULL;
 223
 224   /* If we inlined this variable, we could see it's declaration
 225      again.  */
 226   if (TREE_ASM_WRITTEN (decl))
 227     return;
 228
 229   /* If the DECL_ASSEMBLER_NAME is not the same as the DECL_NAME, then
 230      either we already created RTL for this DECL (and since it was a
 231      local variable, its DECL_ASSEMBLER_NAME got hacked up to prevent
 232      clashes with other local statics with the same name by a previous
 233      call to make_decl_rtl), or the user explicitly requested a
 234      particular assembly name for this variable, using the GNU
 235      extension for this purpose:
 236
 237        int i asm ("j");
 238
 239      There's no way to know which case we're in, here.  But, it turns
 240      out we're safe.  If there's already RTL, then
 241      rest_of_decl_compilation ignores the ASMSPEC parameter, so we
 242      may as well not pass it in.  If there isn't RTL, then we didn't
 243      already create RTL, which means that the modification to
 244      DECL_ASSEMBLER_NAME came only via the explicit extension.  */
 245   if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl)
 246       && !DECL_RTL (decl))
 247     asmspec = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 248
 249   rest_of_decl_compilation (decl, asmspec, /*top_level=*/0, /*at_end=*/0);
 250 }
 251
 252 /* Let the back-end know about DECL.  */
 253
 254 void
 255 emit_local_var (decl)
 256      tree decl;
 257 {
 258   /* Create RTL for this variable.  */
 259   if (!DECL_RTL_SET_P (decl))
 260     {
 261       if (DECL_C_HARD_REGISTER (decl))
 262         /* The user specified an assembler name for this variable.
 263            Set that up now.  */
 264         rest_of_decl_compilation
 265           (decl, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)),
 266            /*top_level=*/0, /*at_end=*/0);
 267       else
 268         expand_decl (decl);
 269     }
 270
 271   /* Actually do the initialization.  */
 272   if (stmts_are_full_exprs_p ())
 273     expand_start_target_temps ();
 274
 275   expand_decl_init (decl);
 276
 277   if (stmts_are_full_exprs_p ())
 278     expand_end_target_temps ();
 279 }
 280
 281 /* Helper for generating the RTL at the beginning of a scope. */
 282
 283 void
 284 genrtl_do_pushlevel ()
 285 {
 286   emit_line_note (input_filename, lineno);
 287   clear_last_expr ();
 288 }
 289
 290 /* Generate the RTL for DESTINATION, which is a GOTO_STMT. */
 291
 292 void
 293 genrtl_goto_stmt (destination)
 294      tree destination;
 295 {
 296   if (TREE_CODE (destination) == IDENTIFIER_NODE)
 297     abort ();
 298
 299   /* We warn about unused labels with -Wunused.  That means we have to
 300      mark the used labels as used.  */
 301   if (TREE_CODE (destination) == LABEL_DECL)
 302     TREE_USED (destination) = 1;
 303
 304   emit_line_note (input_filename, lineno);
 305
 306   if (TREE_CODE (destination) == LABEL_DECL)
 307     {
 308       label_rtx (destination);
 309       expand_goto (destination);
 310     }
 311   else
 312     expand_computed_goto (destination);
 313 }
 314
 315 /* Generate the RTL for EXPR, which is an EXPR_STMT. */
 316
 317 void
 318 genrtl_expr_stmt (expr)
 319      tree expr;
 320 {
 321   if (expr != NULL_TREE)
 322     {
 323       emit_line_note (input_filename, lineno);
 324
 325       if (stmts_are_full_exprs_p ())
 326         expand_start_target_temps ();
 327
 328       if (expr != error_mark_node)
 329         expand_expr_stmt (expr);
 330
 331       if (stmts_are_full_exprs_p ())
 332         expand_end_target_temps ();
 333     }
 334 }
 335
 336 /* Generate the RTL for T, which is a DECL_STMT. */
 337
 338 void
 339 genrtl_decl_stmt (t)
 340      tree t;
 341 {
 342   tree decl;
 343   emit_line_note (input_filename, lineno);
 344   decl = DECL_STMT_DECL (t);
 345   /* If this is a declaration for an automatic local
 346      variable, initialize it.  Note that we might also see a
 347      declaration for a namespace-scope object (declared with
 348      `extern').  We don't have to handle the initialization
 349      of those objects here; they can only be declarations,
 350      rather than definitions.  */
 351   if (TREE_CODE (decl) == VAR_DECL
 352       && !TREE_STATIC (decl)
 353       && !DECL_EXTERNAL (decl))
 354     {
 355       /* Let the back-end know about this variable.  */
 356       if (!anon_aggr_type_p (TREE_TYPE (decl)))
 357         emit_local_var (decl);
 358       else
 359         expand_anon_union_decl (decl, NULL_TREE,
 360                                 DECL_ANON_UNION_ELEMS (decl));
 361     }
 362   else if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl))
 363     make_rtl_for_local_static (decl);
 364   else if (TREE_CODE (decl) == LABEL_DECL
 365            && C_DECLARED_LABEL_FLAG (decl))
 366     declare_nonlocal_label (decl);
 367   else if (lang_expand_decl_stmt)
 368     (*lang_expand_decl_stmt) (t);
 369 }
 370
 371 /* Generate the RTL for T, which is an IF_STMT. */
 372
 373 void
 374 genrtl_if_stmt (t)
 375      tree t;
 376 {
 377   tree cond;
 378   genrtl_do_pushlevel ();
 379   cond = expand_cond (IF_COND (t));
 380   emit_line_note (input_filename, lineno);
 381   expand_start_cond (cond, 0);
 382   if (THEN_CLAUSE (t))
 383     expand_stmt (THEN_CLAUSE (t));
 384   if (ELSE_CLAUSE (t))
 385     {
 386       expand_start_else ();
 387       expand_stmt (ELSE_CLAUSE (t));
 388     }
 389   expand_end_cond ();
 390 }
 391
 392 /* Generate the RTL for T, which is a WHILE_STMT. */
 393
 394 void
 395 genrtl_while_stmt (t)
 396      tree t;
 397 {
 398   tree cond;
 399   emit_nop ();
 400   emit_line_note (input_filename, lineno);
 401   expand_start_loop (1);
 402   genrtl_do_pushlevel ();
 403
 404   cond = expand_cond (WHILE_COND (t));
 405   emit_line_note (input_filename, lineno);
 406   expand_exit_loop_if_false (0, cond);
 407   genrtl_do_pushlevel ();
 408
 409   expand_stmt (WHILE_BODY (t));
 410
 411   expand_end_loop ();
 412 }
 413
 414 /* Generate the RTL for T, which is a DO_STMT. */
 415
 416 void
 417 genrtl_do_stmt (t)
 418      tree t;
 419 {
 420   tree cond = DO_COND (t);
 421
 422   /* Recognize the common special-case of do { ... } while (0) and do
 423      not emit the loop widgetry in this case.  In particular this
 424      avoids cluttering the rtl with dummy loop notes, which can affect
 425      alignment of adjacent labels.  */
 426   if (integer_zerop (cond))
 427     {
 428       expand_start_null_loop ();
 429       expand_stmt (DO_BODY (t));
 430       expand_end_null_loop ();
 431     }
 432   else
 433     {
 434       emit_nop ();
 435       emit_line_note (input_filename, lineno);
 436       expand_start_loop_continue_elsewhere (1);
 437
 438       expand_stmt (DO_BODY (t));
 439
 440       expand_loop_continue_here ();
 441       cond = expand_cond (cond);
 442       emit_line_note (input_filename, lineno);
 443       expand_exit_loop_if_false (0, cond);
 444       expand_end_loop ();
 445     }
 446 }
 447
 448 /* Build the node for a return statement and return it. */
 449
 450 tree
 451 build_return_stmt (expr)
 452      tree expr;
 453 {
 454   return (build_stmt (RETURN_STMT, expr));
 455 }
 456
 457 /* Generate the RTL for STMT, which is a RETURN_STMT. */
 458
 459 void
 460 genrtl_return_stmt (stmt)
 461      tree stmt;
 462 {
 463   tree expr = RETURN_EXPR (stmt);
 464
 465   emit_line_note (input_filename, lineno);
 466   if (!expr)
 467     expand_null_return ();
 468   else
 469     {
 470       expand_start_target_temps ();
 471       expand_return (expr);
 472       expand_end_target_temps ();
 473     }
 474 }
 475
 476 /* Generate the RTL for T, which is a FOR_STMT. */
 477
 478 void
 479 genrtl_for_stmt (t)
 480      tree t;
 481 {
 482   tree cond;
 483   const char *saved_filename;
 484   int saved_lineno;
 485
 486   if (NEW_FOR_SCOPE_P (t))
 487     genrtl_do_pushlevel ();
 488
 489   expand_stmt (FOR_INIT_STMT (t));
 490
 491   /* Expand the initialization.  */
 492   emit_nop ();
 493   emit_line_note (input_filename, lineno);
 494   expand_start_loop_continue_elsewhere (1);
 495   genrtl_do_pushlevel ();
 496   cond = expand_cond (FOR_COND (t));
 497
 498   /* Save the filename and line number so that we expand the FOR_EXPR
 499      we can reset them back to the saved values.  */
 500   saved_filename = input_filename;
 501   saved_lineno = lineno;
 502
 503   /* Expand the condition.  */
 504   emit_line_note (input_filename, lineno);
 505   if (cond)
 506     expand_exit_loop_if_false (0, cond);
 507
 508   /* Expand the body.  */
 509   genrtl_do_pushlevel ();
 510   expand_stmt (FOR_BODY (t));
 511
 512   /* Expand the increment expression.  */
 513   input_filename = saved_filename;
 514   lineno = saved_lineno;
 515   emit_line_note (input_filename, lineno);
 516   expand_loop_continue_here ();
 517   if (FOR_EXPR (t))
 518     genrtl_expr_stmt (FOR_EXPR (t));
 519   expand_end_loop ();
 520 }
 521
 522 /* Build a break statement node and return it. */
 523
 524 tree
 525 build_break_stmt ()
 526 {
 527   return (build_stmt (BREAK_STMT));
 528 }
 529
 530 /* Generate the RTL for a BREAK_STMT. */
 531
 532 void
 533 genrtl_break_stmt ()
 534 {
 535   emit_line_note (input_filename, lineno);
 536   if ( ! expand_exit_something ())
 537     error ("break statement not within loop or switch");
 538 }
 539
 540 /* Build a continue statement node and return it. */
 541
 542 tree
 543 build_continue_stmt ()
 544 {
 545   return (build_stmt (CONTINUE_STMT));
 546 }
 547
 548 /* Generate the RTL for a CONTINUE_STMT. */
 549
 550 void
 551 genrtl_continue_stmt ()
 552 {
 553   emit_line_note (input_filename, lineno);
 554   if (! expand_continue_loop (0))
 555     error ("continue statement not within a loop");
 556 }
 557
 558 /* Generate the RTL for T, which is a SCOPE_STMT. */
 559
 560 void
 561 genrtl_scope_stmt (t)
 562      tree t;
 563 {
 564   tree block = SCOPE_STMT_BLOCK (t);
 565
 566   if (!SCOPE_NO_CLEANUPS_P (t))
 567     {
 568       if (SCOPE_BEGIN_P (t))
 569         expand_start_bindings_and_block (2 * SCOPE_NULLIFIED_P (t), block);
 570       else if (SCOPE_END_P (t))
 571         expand_end_bindings (NULL_TREE, !SCOPE_NULLIFIED_P (t), 0);
 572     }
 573   else if (!SCOPE_NULLIFIED_P (t))
 574     {
 575       rtx note = emit_note (NULL,
 576                             (SCOPE_BEGIN_P (t)
 577                              ? NOTE_INSN_BLOCK_BEG
 578                              : NOTE_INSN_BLOCK_END));
 579       NOTE_BLOCK (note) = block;
 580     }
 581
 582   /* If we're at the end of a scope that contains inlined nested
 583      functions, we have to decide whether or not to write them out.  */
 584   if (block && SCOPE_END_P (t))
 585     {
 586       tree fn;
 587
 588       for (fn = BLOCK_VARS (block); fn; fn = TREE_CHAIN (fn))
 589         {
 590           if (TREE_CODE (fn) == FUNCTION_DECL
 591               && DECL_CONTEXT (fn) == current_function_decl
 592               && !TREE_ASM_WRITTEN (fn)
 593               && TREE_ADDRESSABLE (fn))
 594             {
 595               push_function_context ();
 596               output_inline_function (fn);
 597               pop_function_context ();
 598             }
 599         }
 600     }
 601 }
 602
 603 /* Generate the RTL for T, which is a SWITCH_STMT. */
 604
 605 void
 606 genrtl_switch_stmt (t)
 607      tree t;
 608 {
 609   tree cond;
 610   genrtl_do_pushlevel ();
 611
 612   cond = expand_cond (SWITCH_COND (t));
 613   if (cond == error_mark_node)
 614     /* The code is in error, but we don't want expand_end_case to
 615        crash. */
 616     cond = boolean_false_node;
 617
 618   emit_line_note (input_filename, lineno);
 619   expand_start_case (1, cond, TREE_TYPE (cond), "switch statement");
 620   expand_stmt (SWITCH_BODY (t));
 621   expand_end_case (cond);
 622 }
 623
 624 /* Create a CASE_LABEL tree node and return it. */
 625
 626 tree
 627 build_case_label (low_value, high_value, label_decl)
 628      tree low_value;
 629      tree high_value;
 630      tree label_decl;
 631 {
 632   return build_stmt (CASE_LABEL, low_value, high_value, label_decl);
 633 }
 634
 635
 636 /* Generate the RTL for a CASE_LABEL. */
 637
 638 void
 639 genrtl_case_label (case_label)
 640      tree case_label;
 641 {
 642   tree duplicate;
 643   tree cleanup;
 644
 645   cleanup = last_cleanup_this_contour ();
 646   if (cleanup)
 647     {
 648       static int explained = 0;
 649       warning_with_decl (TREE_PURPOSE (cleanup),
 650                          "destructor needed for `%#D'");
 651       warning ("where case label appears here");
 652       if (!explained)
 653         {
 654           warning ("(enclose actions of previous case statements requiring destructors in their own scope.)");
 655           explained = 1;
 656         }
 657     }
 658
 659   add_case_node (CASE_LOW (case_label), CASE_HIGH (case_label),
 660                  CASE_LABEL_DECL (case_label), &duplicate);
 661 }
 662
 663 /* Generate the RTL for T, which is a COMPOUND_STMT. */
 664
 665 void
 666 genrtl_compound_stmt (t)
 667     tree t;
 668 {
 669   expand_stmt (COMPOUND_BODY (t));
 670 }
 671
 672 /* Generate the RTL for an ASM_STMT. */
 673
 674 void
 675 genrtl_asm_stmt (cv_qualifier, string, output_operands,
 676                  input_operands, clobbers, asm_input_p)
 677      tree cv_qualifier;
 678      tree string;
 679      tree output_operands;
 680      tree input_operands;
 681      tree clobbers;
 682      int asm_input_p;
 683 {
 684   if (cv_qualifier != NULL_TREE
 685       && cv_qualifier != ridpointers[(int) RID_VOLATILE])
 686     {
 687       warning ("%s qualifier ignored on asm",
 688                IDENTIFIER_POINTER (cv_qualifier));
 689       cv_qualifier = NULL_TREE;
 690     }
 691
 692   emit_line_note (input_filename, lineno);
 693   if (asm_input_p)
 694     expand_asm (string);
 695   else
 696     c_expand_asm_operands (string, output_operands, input_operands,
 697                            clobbers, cv_qualifier != NULL_TREE,
 698                            input_filename, lineno);
 699 }
 700
 701 /* Generate the RTL for a DECL_CLEANUP. */
 702
 703 void
 704 genrtl_decl_cleanup (decl, cleanup)
 705      tree decl;
 706      tree cleanup;
 707 {
 708   if (!decl || (DECL_SIZE (decl) && TREE_TYPE (decl) != error_mark_node))
 709     expand_decl_cleanup (decl, cleanup);
 710 }
 711
 712 /* We're about to expand T, a statement.  Set up appropriate context
 713    for the substitution.  */
 714
 715 void
 716 prep_stmt (t)
 717      tree t;
 718 {
 719   if (!STMT_LINENO_FOR_FN_P (t))
 720     lineno = STMT_LINENO (t);
 721   current_stmt_tree ()->stmts_are_full_exprs_p = STMT_IS_FULL_EXPR_P (t);
 722 }
 723
 724 /* Generate the RTL for the statement T, its substatements, and any
 725    other statements at its nesting level. */
 726
 727 void
 728 expand_stmt (t)
 729      tree t;
 730 {
 731   while (t && t != error_mark_node)
 732     {
 733       int saved_stmts_are_full_exprs_p;
 734
 735       /* Set up context appropriately for handling this statement.  */
 736       saved_stmts_are_full_exprs_p = stmts_are_full_exprs_p ();
 737       prep_stmt (t);
 738
 739       switch (TREE_CODE (t))
 740         {
 741         case RETURN_STMT:
 742           genrtl_return_stmt (t);
 743           break;
 744
 745         case EXPR_STMT:
 746           genrtl_expr_stmt (EXPR_STMT_EXPR (t));
 747           break;
 748
 749         case DECL_STMT:
 750           genrtl_decl_stmt (t);
 751           break;
 752
 753         case FOR_STMT:
 754           genrtl_for_stmt (t);
 755           break;
 756
 757         case WHILE_STMT:
 758           genrtl_while_stmt (t);
 759           break;
 760
 761         case DO_STMT:
 762           genrtl_do_stmt (t);
 763           break;
 764
 765         case IF_STMT:
 766           genrtl_if_stmt (t);
 767           break;
 768
 769         case COMPOUND_STMT:
 770           genrtl_compound_stmt (t);
 771           break;
 772
 773         case BREAK_STMT:
 774           genrtl_break_stmt ();
 775           break;
 776
 777         case CONTINUE_STMT:
 778           genrtl_continue_stmt ();
 779           break;
 780
 781         case SWITCH_STMT:
 782           genrtl_switch_stmt (t);
 783           break;
 784
 785         case CASE_LABEL:
 786           genrtl_case_label (t);
 787           break;
 788
 789         case LABEL_STMT:
 790           expand_label (LABEL_STMT_LABEL (t));
 791           break;
 792
 793         case GOTO_STMT:
 794           genrtl_goto_stmt (GOTO_DESTINATION (t));
 795           break;
 796
 797         case ASM_STMT:
 798           genrtl_asm_stmt (ASM_CV_QUAL (t), ASM_STRING (t),
 799                            ASM_OUTPUTS (t), ASM_INPUTS (t),
 800                            ASM_CLOBBERS (t), ASM_INPUT_P (t));
 801           break;
 802
 803         case SCOPE_STMT:
 804           genrtl_scope_stmt (t);
 805           break;
 806
 807         default:
 808           if (lang_expand_stmt)
 809             (*lang_expand_stmt) (t);
 810           else
 811             abort ();
 812           break;
 813         }
 814
 815       /* Restore saved state.  */
 816       current_stmt_tree ()->stmts_are_full_exprs_p
 817         = saved_stmts_are_full_exprs_p;
 818
 819       /* Go on to the next statement in this scope.  */
 820       t = TREE_CHAIN (t);
 821     }
 822 }
 823