gcc/c-pragma.c

   1 /* Handle #pragma, system V.4 style.  Supports #pragma weak and #pragma pack.
   2    Copyright (C) 1992, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   3    2006, 2007 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "rtl.h"
  26 #include "tree.h"
  27 #include "function.h"
  28 #include "cpplib.h"
  29 #include "c-pragma.h"
  30 #include "flags.h"
  31 #include "toplev.h"
  32 #include "ggc.h"
  33 #include "c-common.h"
  34 #include "output.h"
  35 #include "tm_p.h"
  36 #include "vec.h"
  37 #include "target.h"
  38 #include "diagnostic.h"
  39 #include "opts.h"
  40
  41 #define GCC_BAD(gmsgid) \
  42   do { warning (OPT_Wpragmas, gmsgid); return; } while (0)
  43 #define GCC_BAD2(gmsgid, arg) \
  44   do { warning (OPT_Wpragmas, gmsgid, arg); return; } while (0)
  45
  46 typedef struct align_stack GTY(())
  47 {
  48   int                  alignment;
  49   tree                 id;
  50   struct align_stack * prev;
  51 } align_stack;
  52
  53 static GTY(()) struct align_stack * alignment_stack;
  54
  55 #ifdef HANDLE_PRAGMA_PACK
  56 static void handle_pragma_pack (cpp_reader *);
  57
  58 #ifdef HANDLE_PRAGMA_PACK_PUSH_POP
  59 /* If we have a "global" #pragma pack(<n>) in effect when the first
  60    #pragma pack(push,<n>) is encountered, this stores the value of
  61    maximum_field_alignment in effect.  When the final pop_alignment()
  62    happens, we restore the value to this, not to a value of 0 for
  63    maximum_field_alignment.  Value is in bits.  */
  64 static int default_alignment;
  65 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = *(alignment_stack == NULL \
  66         ? &default_alignment \
  67         : &alignment_stack->alignment) = (ALIGN))
  68
  69 static void push_alignment (int, tree);
  70 static void pop_alignment (tree);
  71
  72 /* Push an alignment value onto the stack.  */
  73 static void
  74 push_alignment (int alignment, tree id)
  75 {
  76   align_stack * entry;
  77
  78   entry = GGC_NEW (align_stack);
  79
  80   entry->alignment  = alignment;
  81   entry->id         = id;
  82   entry->prev       = alignment_stack;
  83
  84   /* The current value of maximum_field_alignment is not necessarily
  85      0 since there may be a #pragma pack(<n>) in effect; remember it
  86      so that we can restore it after the final #pragma pop().  */
  87   if (alignment_stack == NULL)
  88     default_alignment = maximum_field_alignment;
  89
  90   alignment_stack = entry;
  91
  92   maximum_field_alignment = alignment;
  93 }
  94
  95 /* Undo a push of an alignment onto the stack.  */
  96 static void
  97 pop_alignment (tree id)
  98 {
  99   align_stack * entry;
 100
 101   if (alignment_stack == NULL)
 102     GCC_BAD ("#pragma pack (pop) encountered without matching #pragma pack (push)");
 103
 104   /* If we got an identifier, strip away everything above the target
 105      entry so that the next step will restore the state just below it.  */
 106   if (id)
 107     {
 108       for (entry = alignment_stack; entry; entry = entry->prev)
 109         if (entry->id == id)
 110           {
 111             alignment_stack = entry;
 112             break;
 113           }
 114       if (entry == NULL)
 115         warning (OPT_Wpragmas, "\
 116 #pragma pack(pop, %s) encountered without matching #pragma pack(push, %s)"
 117                  , IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
 118     }
 119
 120   entry = alignment_stack->prev;
 121
 122   maximum_field_alignment = entry ? entry->alignment : default_alignment;
 123
 124   alignment_stack = entry;
 125 }
 126 #else  /* not HANDLE_PRAGMA_PACK_PUSH_POP */
 127 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = (ALIGN))
 128 #define push_alignment(ID, N) \
 129     GCC_BAD ("#pragma pack(push[, id], <n>) is not supported on this target")
 130 #define pop_alignment(ID) \
 131     GCC_BAD ("#pragma pack(pop[, id], <n>) is not supported on this target")
 132 #endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
 133
 134 /* #pragma pack ()
 135    #pragma pack (N)
 136
 137    #pragma pack (push)
 138    #pragma pack (push, N)
 139    #pragma pack (push, ID)
 140    #pragma pack (push, ID, N)
 141    #pragma pack (pop)
 142    #pragma pack (pop, ID) */
 143 static void
 144 handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy))
 145 {
 146   tree x, id = 0;
 147   int align = -1;
 148   enum cpp_ttype token;
 149   enum { set, push, pop } action;
 150
 151   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 152     GCC_BAD ("missing %<(%> after %<#pragma pack%> - ignored");
 153
 154   token = pragma_lex (&x);
 155   if (token == CPP_CLOSE_PAREN)
 156     {
 157       action = set;
 158       align = initial_max_fld_align;
 159     }
 160   else if (token == CPP_NUMBER)
 161     {
 162       if (TREE_CODE (x) != INTEGER_CST)
 163         GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");
 164       align = TREE_INT_CST_LOW (x);
 165       action = set;
 166       if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 167         GCC_BAD ("malformed %<#pragma pack%> - ignored");
 168     }
 169   else if (token == CPP_NAME)
 170     {
 171 #define GCC_BAD_ACTION do { if (action != pop) \
 172           GCC_BAD ("malformed %<#pragma pack(push[, id][, <n>])%> - ignored"); \
 173         else \
 174           GCC_BAD ("malformed %<#pragma pack(pop[, id])%> - ignored"); \
 175         } while (0)
 176
 177       const char *op = IDENTIFIER_POINTER (x);
 178       if (!strcmp (op, "push"))
 179         action = push;
 180       else if (!strcmp (op, "pop"))
 181         action = pop;
 182       else
 183         GCC_BAD2 ("unknown action %qs for %<#pragma pack%> - ignored", op);
 184
 185       while ((token = pragma_lex (&x)) == CPP_COMMA)
 186         {
 187           token = pragma_lex (&x);
 188           if (token == CPP_NAME && id == 0)
 189             {
 190               id = x;
 191             }
 192           else if (token == CPP_NUMBER && action == push && align == -1)
 193             {
 194               if (TREE_CODE (x) != INTEGER_CST)
 195                 GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");
 196               align = TREE_INT_CST_LOW (x);
 197               if (align == -1)
 198                 action = set;
 199             }
 200           else
 201             GCC_BAD_ACTION;
 202         }
 203
 204       if (token != CPP_CLOSE_PAREN)
 205         GCC_BAD_ACTION;
 206 #undef GCC_BAD_ACTION
 207     }
 208   else
 209     GCC_BAD ("malformed %<#pragma pack%> - ignored");
 210
 211   if (pragma_lex (&x) != CPP_EOF)
 212     warning (OPT_Wpragmas, "junk at end of %<#pragma pack%>");
 213
 214   if (flag_pack_struct)
 215     GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored");
 216
 217   if (action != pop)
 218     switch (align)
 219       {
 220       case 0:
 221       case 1:
 222       case 2:
 223       case 4:
 224       case 8:
 225       case 16:
 226         align *= BITS_PER_UNIT;
 227         break;
 228       case -1:
 229         if (action == push)
 230           {
 231             align = maximum_field_alignment;
 232             break;
 233           }
 234       default:
 235         GCC_BAD2 ("alignment must be a small power of two, not %d", align);
 236       }
 237
 238   switch (action)
 239     {
 240     case set:   SET_GLOBAL_ALIGNMENT (align);  break;
 241     case push:  push_alignment (align, id);    break;
 242     case pop:   pop_alignment (id);            break;
 243     }
 244 }
 245 #endif  /* HANDLE_PRAGMA_PACK */
 246
 247 struct def_pragma_macro_value GTY(())
 248 {
 249   struct def_pragma_macro_value *prev;
 250   cpp_macro *value;
 251 };
 252
 253 struct def_pragma_macro GTY(())
 254 {
 255   hashval_t hash;
 256   const char *name;
 257   struct def_pragma_macro_value value;
 258 };
 259
 260 static GTY((param_is (struct def_pragma_macro))) htab_t pushed_macro_table;
 261
 262 #ifdef HANDLE_PRAGMA_PUSH_POP_MACRO
 263 /* Hash table control functions for pushed_macro_table.  */
 264 static hashval_t
 265 dpm_hash (const void *p)
 266 {
 267   return ((const struct def_pragma_macro *)p)->hash;
 268 }
 269
 270 static int
 271 dpm_eq (const void *pa, const void *pb)
 272 {
 273   const struct def_pragma_macro *a = pa, *b = pb;
 274   return a->hash == b->hash && strcmp (a->name, b->name) == 0;
 275 }
 276
 277 /* #pragma push_macro("MACRO_NAME")
 278    #pragma pop_macro("MACRO_NAME") */
 279
 280 static void
 281 handle_pragma_push_macro (cpp_reader *reader)
 282 {
 283   tree x, id = 0;
 284   enum cpp_ttype token;
 285   struct def_pragma_macro dummy, *c;
 286   const char *macroname;
 287   void **slot;
 288
 289   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 290     GCC_BAD ("missing %<(%> after %<#pragma push_macro%> - ignored");
 291
 292   token = pragma_lex (&id);
 293
 294   /* Silently ignore */
 295   if (token == CPP_CLOSE_PAREN)
 296     return;
 297   if (token != CPP_STRING)
 298     GCC_BAD ("invalid constant in %<#pragma push_macro%> - ignored");
 299
 300   if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 301     GCC_BAD ("missing %<)%> after %<#pragma push_macro%> - ignored");
 302
 303   if (pragma_lex (&x) != CPP_EOF)
 304     warning (OPT_Wpragmas, "junk at end of %<#pragma push_macro%>");
 305
 306   /* Check for empty string, and silently ignore.  */
 307   if (TREE_STRING_LENGTH (id) < 1)
 308     return;
 309   macroname = TREE_STRING_POINTER (id);
 310
 311   if (pushed_macro_table == NULL)
 312     pushed_macro_table = htab_create_ggc (15, dpm_hash, dpm_eq, 0);
 313
 314   dummy.hash = htab_hash_string (macroname);
 315   dummy.name = macroname;
 316   slot = htab_find_slot_with_hash (pushed_macro_table, &dummy,
 317                                    dummy.hash, INSERT);
 318   c = *slot;
 319   if (c == NULL)
 320     {
 321       *slot = c = ggc_alloc (sizeof (struct def_pragma_macro));
 322       c->hash = dummy.hash;
 323       c->name = ggc_alloc_string (macroname, TREE_STRING_LENGTH (id) - 1);
 324       c->value.prev = NULL;
 325     }
 326   else
 327     {
 328       struct def_pragma_macro_value *v;
 329       v = ggc_alloc (sizeof (struct def_pragma_macro_value));
 330       *v = c->value;
 331       c->value.prev = v;
 332     }
 333
 334   c->value.value = cpp_push_definition (reader, macroname);
 335 }
 336
 337 static void
 338 handle_pragma_pop_macro (cpp_reader *reader)
 339 {
 340   tree x, id = 0;
 341   enum cpp_ttype token;
 342   struct def_pragma_macro dummy, *c;
 343   const char *macroname;
 344   void **slot;
 345
 346   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 347     GCC_BAD ("missing %<(%> after %<#pragma pop_macro%> - ignored");
 348
 349   token = pragma_lex (&id);
 350
 351   /* Silently ignore */
 352   if (token == CPP_CLOSE_PAREN)
 353     return;
 354   if (token != CPP_STRING)
 355     GCC_BAD ("invalid constant in %<#pragma pop_macro%> - ignored");
 356
 357   if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 358     GCC_BAD ("missing %<)%> after %<#pragma pop_macro%> - ignored");
 359
 360   if (pragma_lex (&x) != CPP_EOF)
 361     warning (OPT_Wpragmas, "junk at end of %<#pragma pop_macro%>");
 362
 363   /* Check for empty string, and silently ignore.  */
 364   if (TREE_STRING_LENGTH (id) < 1)
 365     return;
 366   macroname = TREE_STRING_POINTER (id);
 367
 368   dummy.hash = htab_hash_string (macroname);
 369   dummy.name = macroname;
 370   slot = htab_find_slot_with_hash (pushed_macro_table, &dummy,
 371                                    dummy.hash, NO_INSERT);
 372   if (slot == NULL)
 373     return;
 374   c = *slot;
 375
 376   cpp_pop_definition (reader, c->name, c->value.value);
 377
 378   if (c->value.prev)
 379     c->value = *c->value.prev;
 380   else
 381     htab_clear_slot (pushed_macro_table, slot);
 382 }
 383 #endif /* HANDLE_PRAGMA_PUSH_POP_MACRO */
 384
 385 static GTY(()) tree pending_weaks;
 386
 387 #ifdef HANDLE_PRAGMA_WEAK
 388 static void apply_pragma_weak (tree, tree);
 389 static void handle_pragma_weak (cpp_reader *);
 390
 391 static void
 392 apply_pragma_weak (tree decl, tree value)
 393 {
 394   if (value)
 395     {
 396       value = build_string (IDENTIFIER_LENGTH (value),
 397                             IDENTIFIER_POINTER (value));
 398       decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
 399                                                build_tree_list (NULL, value)),
 400                        0);
 401     }
 402
 403   if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
 404       && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma.  */
 405       && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
 406     warning (OPT_Wpragmas, "applying #pragma weak %q+D after first use "
 407              "results in unspecified behavior", decl);
 408
 409   declare_weak (decl);
 410 }
 411
 412 void
 413 maybe_apply_pragma_weak (tree decl)
 414 {
 415   tree *p, t, id;
 416
 417   /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed.  */
 418
 419   /* No weak symbols pending, take the short-cut.  */
 420   if (!pending_weaks)
 421     return;
 422   /* If it's not visible outside this file, it doesn't matter whether
 423      it's weak.  */
 424   if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
 425     return;
 426   /* If it's not a function or a variable, it can't be weak.
 427      FIXME: what kinds of things are visible outside this file but
 428      aren't functions or variables?   Should this be an assert instead?  */
 429   if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 430     return;
 431
 432   id = DECL_ASSEMBLER_NAME (decl);
 433
 434   for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
 435     if (id == TREE_PURPOSE (t))
 436       {
 437         apply_pragma_weak (decl, TREE_VALUE (t));
 438         *p = TREE_CHAIN (t);
 439         break;
 440       }
 441 }
 442
 443 /* Process all "#pragma weak A = B" directives where we have not seen
 444    a decl for A.  */
 445 void
 446 maybe_apply_pending_pragma_weaks (void)
 447 {
 448   tree *p, t, alias_id, id, decl, *next;
 449
 450   for (p = &pending_weaks; (t = *p) ; p = next)
 451     {
 452       next = &TREE_CHAIN (t);
 453       alias_id = TREE_PURPOSE (t);
 454       id = TREE_VALUE (t);
 455
 456       if (TREE_VALUE (t) == NULL)
 457         continue;
 458
 459       decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
 460
 461       DECL_ARTIFICIAL (decl) = 1;
 462       TREE_PUBLIC (decl) = 1;
 463       DECL_EXTERNAL (decl) = 1;
 464       DECL_WEAK (decl) = 1;
 465
 466       assemble_alias (decl, id);
 467     }
 468 }
 469
 470 /* #pragma weak name [= value] */
 471 static void
 472 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
 473 {
 474   tree name, value, x, decl;
 475   enum cpp_ttype t;
 476
 477   value = 0;
 478
 479   if (pragma_lex (&name) != CPP_NAME)
 480     GCC_BAD ("malformed #pragma weak, ignored");
 481   t = pragma_lex (&x);
 482   if (t == CPP_EQ)
 483     {
 484       if (pragma_lex (&value) != CPP_NAME)
 485         GCC_BAD ("malformed #pragma weak, ignored");
 486       t = pragma_lex (&x);
 487     }
 488   if (t != CPP_EOF)
 489     warning (OPT_Wpragmas, "junk at end of %<#pragma weak%>");
 490
 491   decl = identifier_global_value (name);
 492   if (decl && DECL_P (decl))
 493     {
 494       apply_pragma_weak (decl, value);
 495       if (value)
 496         assemble_alias (decl, value);
 497     }
 498   else
 499     pending_weaks = tree_cons (name, value, pending_weaks);
 500 }
 501 #else
 502 void
 503 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
 504 {
 505 }
 506
 507 void
 508 maybe_apply_pending_pragma_weaks (void)
 509 {
 510 }
 511 #endif /* HANDLE_PRAGMA_WEAK */
 512
 513 /* GCC supports two #pragma directives for renaming the external
 514    symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
 515    compatibility with the Solaris and Tru64 system headers.  GCC also
 516    has its own notation for this, __asm__("name") annotations.
 517
 518    Corner cases of these features and their interaction:
 519
 520    1) Both pragmas silently apply only to declarations with external
 521       linkage (that is, TREE_PUBLIC || DECL_EXTERNAL).  Asm labels
 522       do not have this restriction.
 523
 524    2) In C++, both #pragmas silently apply only to extern "C" declarations.
 525       Asm labels do not have this restriction.
 526
 527    3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
 528       applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
 529       new name is different, a warning issues and the name does not change.
 530
 531    4) The "source name" for #pragma redefine_extname is the DECL_NAME,
 532       *not* the DECL_ASSEMBLER_NAME.
 533
 534    5) If #pragma extern_prefix is in effect and a declaration occurs
 535       with an __asm__ name, the #pragma extern_prefix is silently
 536       ignored for that declaration.
 537
 538    6) If #pragma extern_prefix and #pragma redefine_extname apply to
 539       the same declaration, whichever triggered first wins, and a warning
 540       is issued.  (We would like to have #pragma redefine_extname always
 541       win, but it can appear either before or after the declaration, and
 542       if it appears afterward, we have no way of knowing whether a modified
 543       DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.)  */
 544
 545 static GTY(()) tree pending_redefine_extname;
 546
 547 static void handle_pragma_redefine_extname (cpp_reader *);
 548
 549 /* #pragma redefine_extname oldname newname */
 550 static void
 551 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
 552 {
 553   tree oldname, newname, decl, x;
 554   enum cpp_ttype t;
 555
 556   if (pragma_lex (&oldname) != CPP_NAME)
 557     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 558   if (pragma_lex (&newname) != CPP_NAME)
 559     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 560   t = pragma_lex (&x);
 561   if (t != CPP_EOF)
 562     warning (OPT_Wpragmas, "junk at end of %<#pragma redefine_extname%>");
 563
 564   if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
 565     {
 566       if (warn_unknown_pragmas > in_system_header)
 567         warning (OPT_Wunknown_pragmas,
 568                  "#pragma redefine_extname not supported on this target");
 569       return;
 570     }
 571
 572   decl = identifier_global_value (oldname);
 573   if (decl
 574       && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
 575       && (TREE_CODE (decl) == FUNCTION_DECL
 576           || TREE_CODE (decl) == VAR_DECL)
 577       && has_c_linkage (decl))
 578     {
 579       if (DECL_ASSEMBLER_NAME_SET_P (decl))
 580         {
 581           const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 582           name = targetm.strip_name_encoding (name);
 583
 584           if (strcmp (name, IDENTIFIER_POINTER (newname)))
 585             warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 586                      "conflict with previous rename");
 587         }
 588       else
 589         change_decl_assembler_name (decl, newname);
 590     }
 591   else
 592     /* We have to add this to the rename list even if there's already
 593        a global value that doesn't meet the above criteria, because in
 594        C++ "struct foo {...};" puts "foo" in the current namespace but
 595        does *not* conflict with a subsequent declaration of a function
 596        or variable foo.  See g++.dg/other/pragma-re-2.C.  */
 597     add_to_renaming_pragma_list (oldname, newname);
 598 }
 599
 600 /* This is called from here and from ia64.c.  */
 601 void
 602 add_to_renaming_pragma_list (tree oldname, tree newname)
 603 {
 604   tree previous = purpose_member (oldname, pending_redefine_extname);
 605   if (previous)
 606     {
 607       if (TREE_VALUE (previous) != newname)
 608         warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 609                  "conflict with previous #pragma redefine_extname");
 610       return;
 611     }
 612
 613   pending_redefine_extname
 614     = tree_cons (oldname, newname, pending_redefine_extname);
 615 }
 616
 617 static GTY(()) tree pragma_extern_prefix;
 618
 619 /* #pragma extern_prefix "prefix" */
 620 static void
 621 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
 622 {
 623   tree prefix, x;
 624   enum cpp_ttype t;
 625
 626   if (pragma_lex (&prefix) != CPP_STRING)
 627     GCC_BAD ("malformed #pragma extern_prefix, ignored");
 628   t = pragma_lex (&x);
 629   if (t != CPP_EOF)
 630     warning (OPT_Wpragmas, "junk at end of %<#pragma extern_prefix%>");
 631
 632   if (targetm.handle_pragma_extern_prefix)
 633     /* Note that the length includes the null terminator.  */
 634     pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
 635   else if (warn_unknown_pragmas > in_system_header)
 636     warning (OPT_Wunknown_pragmas,
 637              "#pragma extern_prefix not supported on this target");
 638 }
 639
 640 /* Hook from the front ends to apply the results of one of the preceding
 641    pragmas that rename variables.  */
 642
 643 tree
 644 maybe_apply_renaming_pragma (tree decl, tree asmname)
 645 {
 646   tree *p, t;
 647
 648   /* The renaming pragmas are only applied to declarations with
 649      external linkage.  */
 650   if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 651       || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
 652       || !has_c_linkage (decl))
 653     return asmname;
 654
 655   /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
 656      but we may warn about a rename that conflicts.  */
 657   if (DECL_ASSEMBLER_NAME_SET_P (decl))
 658     {
 659       const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 660       oldname = targetm.strip_name_encoding (oldname);
 661
 662       if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
 663           warning (OPT_Wpragmas, "asm declaration ignored due to "
 664                    "conflict with previous rename");
 665
 666       /* Take any pending redefine_extname off the list.  */
 667       for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 668         if (DECL_NAME (decl) == TREE_PURPOSE (t))
 669           {
 670             /* Only warn if there is a conflict.  */
 671             if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
 672               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 673                        "conflict with previous rename");
 674
 675             *p = TREE_CHAIN (t);
 676             break;
 677           }
 678       return 0;
 679     }
 680
 681   /* Find out if we have a pending #pragma redefine_extname.  */
 682   for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 683     if (DECL_NAME (decl) == TREE_PURPOSE (t))
 684       {
 685         tree newname = TREE_VALUE (t);
 686         *p = TREE_CHAIN (t);
 687
 688         /* If we already have an asmname, #pragma redefine_extname is
 689            ignored (with a warning if it conflicts).  */
 690         if (asmname)
 691           {
 692             if (strcmp (TREE_STRING_POINTER (asmname),
 693                         IDENTIFIER_POINTER (newname)) != 0)
 694               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 695                        "conflict with __asm__ declaration");
 696             return asmname;
 697           }
 698
 699         /* Otherwise we use what we've got; #pragma extern_prefix is
 700            silently ignored.  */
 701         return build_string (IDENTIFIER_LENGTH (newname),
 702                              IDENTIFIER_POINTER (newname));
 703       }
 704
 705   /* If we've got an asmname, #pragma extern_prefix is silently ignored.  */
 706   if (asmname)
 707     return asmname;
 708
 709   /* If #pragma extern_prefix is in effect, apply it.  */
 710   if (pragma_extern_prefix)
 711     {
 712       const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
 713       size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
 714
 715       const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
 716       size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
 717
 718       char *newname = (char *) alloca (plen + ilen + 1);
 719
 720       memcpy (newname,        prefix, plen);
 721       memcpy (newname + plen, id, ilen + 1);
 722
 723       return build_string (plen + ilen, newname);
 724     }
 725
 726   /* Nada.  */
 727   return 0;
 728 }
 729
 730
 731 #ifdef HANDLE_PRAGMA_VISIBILITY
 732 static void handle_pragma_visibility (cpp_reader *);
 733
 734 typedef enum symbol_visibility visibility;
 735 DEF_VEC_I (visibility);
 736 DEF_VEC_ALLOC_I (visibility, heap);
 737 static VEC (visibility, heap) *visstack;
 738
 739 /* Push the visibility indicated by STR onto the top of the #pragma
 740    visibility stack.  */
 741
 742 void
 743 push_visibility (const char *str)
 744 {
 745   VEC_safe_push (visibility, heap, visstack,
 746                  default_visibility);
 747   if (!strcmp (str, "default"))
 748     default_visibility = VISIBILITY_DEFAULT;
 749   else if (!strcmp (str, "internal"))
 750     default_visibility = VISIBILITY_INTERNAL;
 751   else if (!strcmp (str, "hidden"))
 752     default_visibility = VISIBILITY_HIDDEN;
 753   else if (!strcmp (str, "protected"))
 754     default_visibility = VISIBILITY_PROTECTED;
 755   else
 756     GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
 757   visibility_options.inpragma = 1;
 758 }
 759
 760 /* Pop a level of the #pragma visibility stack.  */
 761
 762 void
 763 pop_visibility (void)
 764 {
 765   default_visibility = VEC_pop (visibility, visstack);
 766   visibility_options.inpragma
 767     = VEC_length (visibility, visstack) != 0;
 768 }
 769
 770 /* Sets the default visibility for symbols to something other than that
 771    specified on the command line.  */
 772
 773 static void
 774 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
 775 {
 776   /* Form is #pragma GCC visibility push(hidden)|pop */
 777   tree x;
 778   enum cpp_ttype token;
 779   enum { bad, push, pop } action = bad;
 780
 781   token = pragma_lex (&x);
 782   if (token == CPP_NAME)
 783     {
 784       const char *op = IDENTIFIER_POINTER (x);
 785       if (!strcmp (op, "push"))
 786         action = push;
 787       else if (!strcmp (op, "pop"))
 788         action = pop;
 789     }
 790   if (bad == action)
 791     GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
 792   else
 793     {
 794       if (pop == action)
 795         {
 796           if (!VEC_length (visibility, visstack))
 797             GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>");
 798           else
 799             pop_visibility ();
 800         }
 801       else
 802         {
 803           if (pragma_lex (&x) != CPP_OPEN_PAREN)
 804             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 805           token = pragma_lex (&x);
 806           if (token != CPP_NAME)
 807             GCC_BAD ("malformed #pragma GCC visibility push");
 808           else
 809             push_visibility (IDENTIFIER_POINTER (x));
 810           if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 811             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 812         }
 813     }
 814   if (pragma_lex (&x) != CPP_EOF)
 815     warning (OPT_Wpragmas, "junk at end of %<#pragma GCC visibility%>");
 816 }
 817
 818 #endif
 819
 820 static void
 821 handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))
 822 {
 823   const char *kind_string, *option_string;
 824   unsigned int option_index;
 825   enum cpp_ttype token;
 826   diagnostic_t kind;
 827   tree x;
 828
 829   if (cfun)
 830     {
 831       error ("#pragma GCC diagnostic not allowed inside functions");
 832       return;
 833     }
 834
 835   token = pragma_lex (&x);
 836   if (token != CPP_NAME)
 837     GCC_BAD ("missing [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 838   kind_string = IDENTIFIER_POINTER (x);
 839   if (strcmp (kind_string, "error") == 0)
 840     kind = DK_ERROR;
 841   else if (strcmp (kind_string, "warning") == 0)
 842     kind = DK_WARNING;
 843   else if (strcmp (kind_string, "ignored") == 0)
 844     kind = DK_IGNORED;
 845   else
 846     GCC_BAD ("expected [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 847
 848   token = pragma_lex (&x);
 849   if (token != CPP_STRING)
 850     GCC_BAD ("missing option after %<#pragma GCC diagnostic%> kind");
 851   option_string = TREE_STRING_POINTER (x);
 852   for (option_index = 0; option_index < cl_options_count; option_index++)
 853     if (strcmp (cl_options[option_index].opt_text, option_string) == 0)
 854       {
 855         /* This overrides -Werror, for example.  */
 856         diagnostic_classify_diagnostic (global_dc, option_index, kind);
 857         /* This makes sure the option is enabled, like -Wfoo would do.  */
 858         if (cl_options[option_index].var_type == CLVC_BOOLEAN
 859             && cl_options[option_index].flag_var
 860             && kind != DK_IGNORED)
 861             *(int *) cl_options[option_index].flag_var = 1;
 862         return;
 863       }
 864   GCC_BAD ("unknown option after %<#pragma GCC diagnostic%> kind");
 865 }
 866
 867 /* A vector of registered pragma callbacks.  */
 868
 869 DEF_VEC_O (pragma_handler);
 870 DEF_VEC_ALLOC_O (pragma_handler, heap);
 871
 872 static VEC(pragma_handler, heap) *registered_pragmas;
 873
 874 /* Front-end wrappers for pragma registration to avoid dragging
 875    cpplib.h in almost everywhere.  */
 876
 877 static void
 878 c_register_pragma_1 (const char *space, const char *name,
 879                      pragma_handler handler, bool allow_expansion)
 880 {
 881   unsigned id;
 882
 883   VEC_safe_push (pragma_handler, heap, registered_pragmas, &handler);
 884   id = VEC_length (pragma_handler, registered_pragmas);
 885   id += PRAGMA_FIRST_EXTERNAL - 1;
 886
 887   /* The C++ front end allocates 6 bits in cp_token; the C front end
 888      allocates 7 bits in c_token.  At present this is sufficient.  */
 889   gcc_assert (id < 64);
 890
 891   cpp_register_deferred_pragma (parse_in, space, name, id,
 892                                 allow_expansion, false);
 893 }
 894
 895 void
 896 c_register_pragma (const char *space, const char *name, pragma_handler handler)
 897 {
 898   c_register_pragma_1 (space, name, handler, false);
 899 }
 900
 901 void
 902 c_register_pragma_with_expansion (const char *space, const char *name,
 903                                   pragma_handler handler)
 904 {
 905   c_register_pragma_1 (space, name, handler, true);
 906 }
 907
 908 void
 909 c_invoke_pragma_handler (unsigned int id)
 910 {
 911   pragma_handler handler;
 912
 913   id -= PRAGMA_FIRST_EXTERNAL;
 914   handler = *VEC_index (pragma_handler, registered_pragmas, id);
 915
 916   handler (parse_in);
 917 }
 918
 919 /* Set up front-end pragmas.  */
 920 void
 921 init_pragma (void)
 922 {
 923   if (flag_openmp && !flag_preprocess_only)
 924     {
 925       struct omp_pragma_def { const char *name; unsigned int id; };
 926       static const struct omp_pragma_def omp_pragmas[] = {
 927         { "atomic", PRAGMA_OMP_ATOMIC },
 928         { "barrier", PRAGMA_OMP_BARRIER },
 929         { "critical", PRAGMA_OMP_CRITICAL },
 930         { "flush", PRAGMA_OMP_FLUSH },
 931         { "for", PRAGMA_OMP_FOR },
 932         { "master", PRAGMA_OMP_MASTER },
 933         { "ordered", PRAGMA_OMP_ORDERED },
 934         { "parallel", PRAGMA_OMP_PARALLEL },
 935         { "section", PRAGMA_OMP_SECTION },
 936         { "sections", PRAGMA_OMP_SECTIONS },
 937         { "single", PRAGMA_OMP_SINGLE },
 938         { "threadprivate", PRAGMA_OMP_THREADPRIVATE }
 939       };
 940
 941       const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
 942       int i;
 943
 944       for (i = 0; i < n_omp_pragmas; ++i)
 945         cpp_register_deferred_pragma (parse_in, "omp", omp_pragmas[i].name,
 946                                       omp_pragmas[i].id, true, true);
 947     }
 948
 949   cpp_register_deferred_pragma (parse_in, "GCC", "pch_preprocess",
 950                                 PRAGMA_GCC_PCH_PREPROCESS, false, false);
 951
 952 #ifdef HANDLE_PRAGMA_PACK
 953 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
 954   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 955 #else
 956   c_register_pragma (0, "pack", handle_pragma_pack);
 957 #endif
 958 #endif
 959 #ifdef HANDLE_PRAGMA_PUSH_POP_MACRO
 960   c_register_pragma (0 ,"push_macro", handle_pragma_push_macro);
 961   c_register_pragma (0 ,"pop_macro", handle_pragma_pop_macro);
 962 #endif
 963 #ifdef HANDLE_PRAGMA_WEAK
 964   c_register_pragma (0, "weak", handle_pragma_weak);
 965 #endif
 966 #ifdef HANDLE_PRAGMA_VISIBILITY
 967   c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
 968 #endif
 969
 970   c_register_pragma ("GCC", "diagnostic", handle_pragma_diagnostic);
 971
 972   c_register_pragma_with_expansion (0, "redefine_extname", handle_pragma_redefine_extname);
 973   c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
 974
 975 #ifdef REGISTER_TARGET_PRAGMAS
 976   REGISTER_TARGET_PRAGMAS ();
 977 #endif
 978 }
 979
 980 #include "gt-c-pragma.h"