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 Free Software Foundation, Inc.  Written by
   5    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 "output.h"
  37 #include "timevar.h"
  38
  39 /* Some statements, like for-statements or if-statements, require a
  40    condition.  This condition can be a declaration.  If T is such a
  41    declaration it is processed, and an expression appropriate to use
  42    as the condition is returned.  Otherwise, T itself is returned.  */
  43
  44 tree
  45 expand_cond (t)
  46      tree t;
  47 {
  48   if (t && TREE_CODE (t) == TREE_LIST)
  49     {
  50       expand_stmt (TREE_PURPOSE (t));
  51       return TREE_VALUE (t);
  52     }
  53   else
  54     return t;
  55 }
  56
  57 /* Create RTL for the local static variable DECL.  */
  58
  59 void
  60 make_rtl_for_local_static (decl)
  61      tree decl;
  62 {
  63   const char *asmspec = NULL;
  64
  65   /* If we inlined this variable, we could see it's declaration
  66      again.  */
  67   if (DECL_RTL (decl))
  68     return;
  69
  70   if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
  71     {
  72       /* The only way this situaton can occur is if the
  73          user specified a name for this DECL using the
  74          `attribute' syntax.  */
  75       asmspec = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
  76       DECL_ASSEMBLER_NAME (decl) = DECL_NAME (decl);
  77     }
  78
  79   rest_of_decl_compilation (decl, asmspec, /*top_level=*/0, /*at_end=*/0);
  80 }
  81
  82 /* Let the back-end know about DECL.  */
  83
  84 void
  85 emit_local_var (decl)
  86      tree decl;
  87 {
  88   /* Create RTL for this variable.  */
  89   if (!DECL_RTL (decl))
  90     {
  91       if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
  92         /* The user must have specified an assembler name for this
  93            variable.  Set that up now.  */
  94         rest_of_decl_compilation
  95           (decl, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)),
  96            /*top_level=*/0, /*at_end=*/0);
  97       else
  98         expand_decl (decl);
  99     }
 100
 101   /* Actually do the initialization.  */
 102   if (stmts_are_full_exprs_p ())
 103     expand_start_target_temps ();
 104
 105   expand_decl_init (decl);
 106
 107   if (stmts_are_full_exprs_p ())
 108     expand_end_target_temps ();
 109 }
 110
 111 /* Helper for generating the RTL at the beginning of a scope. */
 112
 113 void
 114 genrtl_do_pushlevel ()
 115 {
 116   emit_line_note (input_filename, lineno);
 117   clear_last_expr ();
 118 }
 119
 120 /* Helper for generating the RTL. */
 121
 122 void
 123 genrtl_clear_out_block ()
 124 {
 125   /* If COND wasn't a declaration, clear out the
 126      block we made for it and start a new one here so the
 127      optimization in expand_end_loop will work.  */
 128   if (getdecls () == NULL_TREE)
 129     genrtl_do_pushlevel ();
 130 }
 131
 132 /* Generate the RTL for DESTINATION, which is a GOTO_STMT. */
 133
 134 void
 135 genrtl_goto_stmt (destination)
 136      tree destination;
 137 {
 138   if (TREE_CODE (destination) == IDENTIFIER_NODE)
 139     abort ();
 140
 141   /* We warn about unused labels with -Wunused.  That means we have to
 142      mark the used labels as used.  */
 143   if (TREE_CODE (destination) == LABEL_DECL)
 144     TREE_USED (destination) = 1;
 145
 146   emit_line_note (input_filename, lineno);
 147
 148   if (TREE_CODE (destination) == LABEL_DECL)
 149     {
 150       label_rtx (destination);
 151       expand_goto (destination);
 152     }
 153   else
 154     expand_computed_goto (destination);
 155 }
 156
 157 /* Generate the RTL for EXPR, which is an EXPR_STMT. */
 158
 159 void
 160 genrtl_expr_stmt (expr)
 161      tree expr;
 162 {
 163   if (expr != NULL_TREE)
 164     {
 165       emit_line_note (input_filename, lineno);
 166
 167       if (stmts_are_full_exprs_p ())
 168         expand_start_target_temps ();
 169
 170       lang_expand_expr_stmt (expr);
 171
 172       if (stmts_are_full_exprs_p ())
 173         expand_end_target_temps ();
 174     }
 175 }
 176
 177 /* Generate the RTL for T, which is a DECL_STMT. */
 178
 179 void
 180 genrtl_decl_stmt (t)
 181      tree t;
 182 {
 183   tree decl;
 184   emit_line_note (input_filename, lineno);
 185   decl = DECL_STMT_DECL (t);
 186   /* If this is a declaration for an automatic local
 187      variable, initialize it.  Note that we might also see a
 188      declaration for a namespace-scope object (declared with
 189      `extern').  We don't have to handle the initialization
 190      of those objects here; they can only be declarations,
 191      rather than definitions.  */
 192   if (TREE_CODE (decl) == VAR_DECL
 193       && !TREE_STATIC (decl)
 194       && !DECL_EXTERNAL (decl))
 195     {
 196       /* Let the back-end know about this variable.  */
 197       if (!anon_aggr_type_p (TREE_TYPE (decl)))
 198         emit_local_var (decl);
 199       else
 200         expand_anon_union_decl (decl, NULL_TREE,
 201                                 DECL_ANON_UNION_ELEMS (decl));
 202     }
 203   else if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl))
 204     {
 205       if (DECL_ARTIFICIAL (decl) && ! TREE_USED (decl))
 206         /* Do not emit unused decls. This is not just an
 207            optimization. We really do not want to emit
 208            __PRETTY_FUNCTION__ etc, if they're never used.  */
 209         DECL_IGNORED_P (decl) = 1;
 210       else
 211         make_rtl_for_local_static (decl);
 212     }
 213 }
 214
 215 /* Generate the RTL for T, which is an IF_STMT. */
 216
 217 void
 218 genrtl_if_stmt (t)
 219      tree t;
 220 {
 221   tree cond;
 222   genrtl_do_pushlevel ();
 223   cond = expand_cond (IF_COND (t));
 224   emit_line_note (input_filename, lineno);
 225   expand_start_cond (cond, 0);
 226   if (THEN_CLAUSE (t))
 227     expand_stmt (THEN_CLAUSE (t));
 228   if (ELSE_CLAUSE (t))
 229     {
 230       expand_start_else ();
 231       expand_stmt (ELSE_CLAUSE (t));
 232     }
 233   expand_end_cond ();
 234 }
 235
 236 /* Generate the RTL for T, which is a WHILE_STMT. */
 237
 238 void
 239 genrtl_while_stmt (t)
 240      tree t;
 241 {
 242   tree cond;
 243   emit_nop ();
 244   emit_line_note (input_filename, lineno);
 245   expand_start_loop (1);
 246   genrtl_do_pushlevel ();
 247
 248   cond = expand_cond (WHILE_COND (t));
 249   emit_line_note (input_filename, lineno);
 250   expand_exit_loop_if_false (0, cond);
 251   genrtl_clear_out_block ();
 252
 253   expand_stmt (WHILE_BODY (t));
 254
 255   expand_end_loop ();
 256 }
 257
 258 /* Generate the RTL for T, which is a DO_STMT. */
 259
 260 void
 261 genrtl_do_stmt (t)
 262      tree t;
 263 {
 264   tree cond;
 265   emit_nop ();
 266   emit_line_note (input_filename, lineno);
 267   expand_start_loop_continue_elsewhere (1);
 268
 269   expand_stmt (DO_BODY (t));
 270
 271   expand_loop_continue_here ();
 272
 273   cond = expand_cond (DO_COND (t));
 274   emit_line_note (input_filename, lineno);
 275   expand_exit_loop_if_false (0, cond);
 276   expand_end_loop ();
 277 }
 278
 279 /* Generate the RTL for EXPR, which is a RETURN_STMT. */
 280
 281 void
 282 genrtl_return_stmt (expr)
 283      tree expr;
 284 {
 285   emit_line_note (input_filename, lineno);
 286   c_expand_return (expr);
 287 }
 288
 289 /* Generate the RTL for T, which is a FOR_STMT. */
 290
 291 void
 292 genrtl_for_stmt (t)
 293      tree t;
 294 {
 295   tree tmp;
 296   tree cond;
 297   if (NEW_FOR_SCOPE_P (t))
 298     genrtl_do_pushlevel ();
 299
 300   expand_stmt (FOR_INIT_STMT (t));
 301
 302   emit_nop ();
 303   emit_line_note (input_filename, lineno);
 304   expand_start_loop_continue_elsewhere (1);
 305   genrtl_do_pushlevel ();
 306   cond = expand_cond (FOR_COND (t));
 307   emit_line_note (input_filename, lineno);
 308   if (cond)
 309     expand_exit_loop_if_false (0, cond);
 310   genrtl_clear_out_block ();
 311   tmp = FOR_EXPR (t);
 312
 313   expand_stmt (FOR_BODY (t));
 314
 315   emit_line_note (input_filename, lineno);
 316   expand_loop_continue_here ();
 317   if (tmp)
 318     genrtl_expr_stmt (tmp);
 319   expand_end_loop ();
 320 }
 321
 322 /* Generate the RTL for a BREAK_STMT. */
 323
 324 void
 325 genrtl_break_stmt ()
 326 {
 327   emit_line_note (input_filename, lineno);
 328   if ( ! expand_exit_something ())
 329     error ("break statement not within loop or switch");
 330 }
 331
 332 /* Generate the RTL for a CONTINUE_STMT. */
 333
 334 void
 335 genrtl_continue_stmt ()
 336 {
 337   emit_line_note (input_filename, lineno);
 338   if (! expand_continue_loop (0))
 339     error ("continue statement not within a loop");
 340 }
 341
 342 /* Generate the RTL for T, which is a SCOPE_STMT. */
 343
 344 void
 345 genrtl_scope_stmt (t)
 346      tree t;
 347 {
 348   if (!SCOPE_NO_CLEANUPS_P (t))
 349     {
 350       if (SCOPE_BEGIN_P (t))
 351         expand_start_bindings_and_block (2 * SCOPE_NULLIFIED_P (t),
 352                                          SCOPE_STMT_BLOCK (t));
 353       else if (SCOPE_END_P (t))
 354         expand_end_bindings (NULL_TREE, !SCOPE_NULLIFIED_P (t), 0);
 355     }
 356   else if (!SCOPE_NULLIFIED_P (t))
 357     {
 358       rtx note = emit_note (NULL,
 359                             (SCOPE_BEGIN_P (t)
 360                              ? NOTE_INSN_BLOCK_BEG
 361                              : NOTE_INSN_BLOCK_END));
 362       NOTE_BLOCK (note) = SCOPE_STMT_BLOCK (t);
 363     }
 364 }
 365
 366 /* Generate the RTL for T, which is a SWITCH_STMT. */
 367
 368 void
 369 genrtl_switch_stmt (t)
 370      tree t;
 371 {
 372   tree cond;
 373   genrtl_do_pushlevel ();
 374
 375   cond = expand_cond (SWITCH_COND (t));
 376   if (cond != error_mark_node)
 377     {
 378       emit_line_note (input_filename, lineno);
 379       c_expand_start_case (cond);
 380     }
 381   else
 382     /* The code is in error, but we don't want expand_end_case to
 383        crash. */
 384     c_expand_start_case (boolean_false_node);
 385
 386   expand_stmt (SWITCH_BODY (t));
 387
 388   expand_end_case (cond);
 389 }
 390
 391 /* Generate the RTL for a CASE_LABEL. */
 392
 393 void
 394 genrtl_case_label (low_value, high_value)
 395      tree low_value;
 396      tree high_value;
 397 {
 398   do_case (low_value, high_value);
 399 }
 400
 401 /* Generate the RTL for T, which is a COMPOUND_STMT. */
 402
 403 void
 404 genrtl_compound_stmt (t)
 405     tree t;
 406 {
 407   /* If this is the outermost block of the function, declare the
 408      variables __FUNCTION__, __PRETTY_FUNCTION__, and so forth.  */
 409   if (cfun
 410       && !current_function_name_declared ()
 411       && !COMPOUND_STMT_NO_SCOPE (t))
 412     {
 413       set_current_function_name_declared (1);
 414       declare_function_name ();
 415     }
 416
 417   expand_stmt (COMPOUND_BODY (t));
 418 }
 419
 420 /* Generate the RTL for an ASM_STMT. */
 421
 422 void
 423 genrtl_asm_stmt (cv_qualifier, string, output_operands,
 424                  input_operands, clobbers)
 425      tree cv_qualifier;
 426      tree string;
 427      tree output_operands;
 428      tree input_operands;
 429      tree clobbers;
 430 {
 431   if (TREE_CHAIN (string))
 432     string = combine_strings (string);
 433
 434   if (cv_qualifier != NULL_TREE
 435       && cv_qualifier != ridpointers[(int) RID_VOLATILE])
 436     {
 437       warning ("%s qualifier ignored on asm",
 438                IDENTIFIER_POINTER (cv_qualifier));
 439       cv_qualifier = NULL_TREE;
 440     }
 441
 442   emit_line_note (input_filename, lineno);
 443   if (output_operands != NULL_TREE || input_operands != NULL_TREE
 444       || clobbers != NULL_TREE)
 445       c_expand_asm_operands (string, output_operands,
 446                              input_operands,
 447                              clobbers,
 448                              cv_qualifier != NULL_TREE,
 449                              input_filename, lineno);
 450   else
 451     expand_asm (string);
 452 }
 453
 454 /* Generate the RTL for a DECL_CLEANUP. */
 455
 456 void
 457 genrtl_decl_cleanup (decl, cleanup)
 458      tree decl;
 459      tree cleanup;
 460 {
 461   if (!decl || (DECL_SIZE (decl) && TREE_TYPE (decl) != error_mark_node))
 462     expand_decl_cleanup (decl, cleanup);
 463 }
 464
 465 /* Generate the RTL for the statement T, its substatements, and any
 466    other statements at its nesting level. */
 467
 468 tree
 469 expand_stmt (t)
 470      tree t;
 471 {
 472   tree rval;
 473   rval = lang_expand_stmt (t);
 474   return rval;
 475 }
 476