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 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 2, 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 COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "rtl.h"
  27 #include "tree.h"
  28 #include "function.h"
  29 #include "cpplib.h"
  30 #include "c-pragma.h"
  31 #include "flags.h"
  32 #include "toplev.h"
  33 #include "ggc.h"
  34 #include "c-common.h"
  35 #include "output.h"
  36 #include "tm_p.h"
  37 #include "vec.h"
  38 #include "target.h"
  39 #include "diagnostic.h"
  40 #include "opts.h"
  41
  42 #define GCC_BAD(gmsgid) \
  43   do { warning (OPT_Wpragmas, gmsgid); return; } while (0)
  44 #define GCC_BAD2(gmsgid, arg) \
  45   do { warning (OPT_Wpragmas, gmsgid, arg); return; } while (0)
  46
  47 typedef struct align_stack GTY(())
  48 {
  49   int                  alignment;
  50   tree                 id;
  51   struct align_stack * prev;
  52 } align_stack;
  53
  54 static GTY(()) struct align_stack * alignment_stack;
  55
  56 #ifdef HANDLE_PRAGMA_PACK
  57 static void handle_pragma_pack (cpp_reader *);
  58
  59 #ifdef HANDLE_PRAGMA_PACK_PUSH_POP
  60 /* If we have a "global" #pragma pack(<n>) in effect when the first
  61    #pragma pack(push,<n>) is encountered, this stores the value of
  62    maximum_field_alignment in effect.  When the final pop_alignment()
  63    happens, we restore the value to this, not to a value of 0 for
  64    maximum_field_alignment.  Value is in bits.  */
  65 static int default_alignment;
  66 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = *(alignment_stack == NULL \
  67         ? &default_alignment \
  68         : &alignment_stack->alignment) = (ALIGN))
  69
  70 static void push_alignment (int, tree);
  71 static void pop_alignment (tree);
  72
  73 /* Push an alignment value onto the stack.  */
  74 static void
  75 push_alignment (int alignment, tree id)
  76 {
  77   align_stack * entry;
  78
  79   entry = GGC_NEW (align_stack);
  80
  81   entry->alignment  = alignment;
  82   entry->id         = id;
  83   entry->prev       = alignment_stack;
  84
  85   /* The current value of maximum_field_alignment is not necessarily
  86      0 since there may be a #pragma pack(<n>) in effect; remember it
  87      so that we can restore it after the final #pragma pop().  */
  88   if (alignment_stack == NULL)
  89     default_alignment = maximum_field_alignment;
  90
  91   alignment_stack = entry;
  92
  93   maximum_field_alignment = alignment;
  94 }
  95
  96 /* Undo a push of an alignment onto the stack.  */
  97 static void
  98 pop_alignment (tree id)
  99 {
 100   align_stack * entry;
 101
 102   if (alignment_stack == NULL)
 103     GCC_BAD ("#pragma pack (pop) encountered without matching #pragma pack (push)");
 104
 105   /* If we got an identifier, strip away everything above the target
 106      entry so that the next step will restore the state just below it.  */
 107   if (id)
 108     {
 109       for (entry = alignment_stack; entry; entry = entry->prev)
 110         if (entry->id == id)
 111           {
 112             alignment_stack = entry;
 113             break;
 114           }
 115       if (entry == NULL)
 116         warning (OPT_Wpragmas, "\
 117 #pragma pack(pop, %s) encountered without matching #pragma pack(push, %s)"
 118                  , IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
 119     }
 120
 121   entry = alignment_stack->prev;
 122
 123   maximum_field_alignment = entry ? entry->alignment : default_alignment;
 124
 125   alignment_stack = entry;
 126 }
 127 #else  /* not HANDLE_PRAGMA_PACK_PUSH_POP */
 128 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = (ALIGN))
 129 #define push_alignment(ID, N) \
 130     GCC_BAD ("#pragma pack(push[, id], <n>) is not supported on this target")
 131 #define pop_alignment(ID) \
 132     GCC_BAD ("#pragma pack(pop[, id], <n>) is not supported on this target")
 133 #endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
 134
 135 /* #pragma pack ()
 136    #pragma pack (N)
 137
 138    #pragma pack (push)
 139    #pragma pack (push, N)
 140    #pragma pack (push, ID)
 141    #pragma pack (push, ID, N)
 142    #pragma pack (pop)
 143    #pragma pack (pop, ID) */
 144 static void
 145 handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy))
 146 {
 147   tree x, id = 0;
 148   int align = -1;
 149   enum cpp_ttype token;
 150   enum { set, push, pop } action;
 151
 152   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 153     GCC_BAD ("missing %<(%> after %<#pragma pack%> - ignored");
 154
 155   token = pragma_lex (&x);
 156   if (token == CPP_CLOSE_PAREN)
 157     {
 158       action = set;
 159       align = initial_max_fld_align;
 160     }
 161   else if (token == CPP_NUMBER)
 162     {
 163       align = TREE_INT_CST_LOW (x);
 164       action = set;
 165       if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 166         GCC_BAD ("malformed %<#pragma pack%> - ignored");
 167     }
 168   else if (token == CPP_NAME)
 169     {
 170 #define GCC_BAD_ACTION do { if (action != pop) \
 171           GCC_BAD ("malformed %<#pragma pack(push[, id][, <n>])%> - ignored"); \
 172         else \
 173           GCC_BAD ("malformed %<#pragma pack(pop[, id])%> - ignored"); \
 174         } while (0)
 175
 176       const char *op = IDENTIFIER_POINTER (x);
 177       if (!strcmp (op, "push"))
 178         action = push;
 179       else if (!strcmp (op, "pop"))
 180         action = pop;
 181       else
 182         GCC_BAD2 ("unknown action %qs for %<#pragma pack%> - ignored", op);
 183
 184       while ((token = pragma_lex (&x)) == CPP_COMMA)
 185         {
 186           token = pragma_lex (&x);
 187           if (token == CPP_NAME && id == 0)
 188             {
 189               id = x;
 190             }
 191           else if (token == CPP_NUMBER && action == push && align == -1)
 192             {
 193               align = TREE_INT_CST_LOW (x);
 194               if (align == -1)
 195                 action = set;
 196             }
 197           else
 198             GCC_BAD_ACTION;
 199         }
 200
 201       if (token != CPP_CLOSE_PAREN)
 202         GCC_BAD_ACTION;
 203 #undef GCC_BAD_ACTION
 204     }
 205   else
 206     GCC_BAD ("malformed %<#pragma pack%> - ignored");
 207
 208   if (pragma_lex (&x) != CPP_EOF)
 209     warning (OPT_Wpragmas, "junk at end of %<#pragma pack%>");
 210
 211   if (flag_pack_struct)
 212     GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored");
 213
 214   if (action != pop)
 215     switch (align)
 216       {
 217       case 0:
 218       case 1:
 219       case 2:
 220       case 4:
 221       case 8:
 222       case 16:
 223         align *= BITS_PER_UNIT;
 224         break;
 225       case -1:
 226         if (action == push)
 227           {
 228             align = maximum_field_alignment;
 229             break;
 230           }
 231       default:
 232         GCC_BAD2 ("alignment must be a small power of two, not %d", align);
 233       }
 234
 235   switch (action)
 236     {
 237     case set:   SET_GLOBAL_ALIGNMENT (align);  break;
 238     case push:  push_alignment (align, id);    break;
 239     case pop:   pop_alignment (id);            break;
 240     }
 241 }
 242 #endif  /* HANDLE_PRAGMA_PACK */
 243
 244 static GTY(()) tree pending_weaks;
 245
 246 #ifdef HANDLE_PRAGMA_WEAK
 247 static void apply_pragma_weak (tree, tree);
 248 static void handle_pragma_weak (cpp_reader *);
 249
 250 static void
 251 apply_pragma_weak (tree decl, tree value)
 252 {
 253   if (value)
 254     {
 255       value = build_string (IDENTIFIER_LENGTH (value),
 256                             IDENTIFIER_POINTER (value));
 257       decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
 258                                                build_tree_list (NULL, value)),
 259                        0);
 260     }
 261
 262   if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
 263       && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma.  */
 264       && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
 265     warning (OPT_Wpragmas, "applying #pragma weak %q+D after first use "
 266              "results in unspecified behavior", decl);
 267
 268   declare_weak (decl);
 269 }
 270
 271 void
 272 maybe_apply_pragma_weak (tree decl)
 273 {
 274   tree *p, t, id;
 275
 276   /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed.  */
 277
 278   /* No weak symbols pending, take the short-cut.  */
 279   if (!pending_weaks)
 280     return;
 281   /* If it's not visible outside this file, it doesn't matter whether
 282      it's weak.  */
 283   if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
 284     return;
 285   /* If it's not a function or a variable, it can't be weak.
 286      FIXME: what kinds of things are visible outside this file but
 287      aren't functions or variables?   Should this be an assert instead?  */
 288   if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 289     return;
 290
 291   id = DECL_ASSEMBLER_NAME (decl);
 292
 293   for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
 294     if (id == TREE_PURPOSE (t))
 295       {
 296         apply_pragma_weak (decl, TREE_VALUE (t));
 297         *p = TREE_CHAIN (t);
 298         break;
 299       }
 300 }
 301
 302 /* Process all "#pragma weak A = B" directives where we have not seen
 303    a decl for A.  */
 304 void
 305 maybe_apply_pending_pragma_weaks (void)
 306 {
 307   tree *p, t, alias_id, id, decl, *next;
 308
 309   for (p = &pending_weaks; (t = *p) ; p = next)
 310     {
 311       next = &TREE_CHAIN (t);
 312       alias_id = TREE_PURPOSE (t);
 313       id = TREE_VALUE (t);
 314
 315       if (TREE_VALUE (t) == NULL)
 316         continue;
 317
 318       decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
 319
 320       DECL_ARTIFICIAL (decl) = 1;
 321       TREE_PUBLIC (decl) = 1;
 322       DECL_EXTERNAL (decl) = 1;
 323       DECL_WEAK (decl) = 1;
 324
 325       assemble_alias (decl, id);
 326     }
 327 }
 328
 329 /* #pragma weak name [= value] */
 330 static void
 331 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
 332 {
 333   tree name, value, x, decl;
 334   enum cpp_ttype t;
 335
 336   value = 0;
 337
 338   if (pragma_lex (&name) != CPP_NAME)
 339     GCC_BAD ("malformed #pragma weak, ignored");
 340   t = pragma_lex (&x);
 341   if (t == CPP_EQ)
 342     {
 343       if (pragma_lex (&value) != CPP_NAME)
 344         GCC_BAD ("malformed #pragma weak, ignored");
 345       t = pragma_lex (&x);
 346     }
 347   if (t != CPP_EOF)
 348     warning (OPT_Wpragmas, "junk at end of %<#pragma weak%>");
 349
 350   decl = identifier_global_value (name);
 351   if (decl && DECL_P (decl))
 352     {
 353       apply_pragma_weak (decl, value);
 354       if (value)
 355         assemble_alias (decl, value);
 356     }
 357   else
 358     pending_weaks = tree_cons (name, value, pending_weaks);
 359 }
 360 #else
 361 void
 362 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
 363 {
 364 }
 365
 366 void
 367 maybe_apply_pending_pragma_weaks (void)
 368 {
 369 }
 370 #endif /* HANDLE_PRAGMA_WEAK */
 371
 372 /* GCC supports two #pragma directives for renaming the external
 373    symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
 374    compatibility with the Solaris and Tru64 system headers.  GCC also
 375    has its own notation for this, __asm__("name") annotations.
 376
 377    Corner cases of these features and their interaction:
 378
 379    1) Both pragmas silently apply only to declarations with external
 380       linkage (that is, TREE_PUBLIC || DECL_EXTERNAL).  Asm labels
 381       do not have this restriction.
 382
 383    2) In C++, both #pragmas silently apply only to extern "C" declarations.
 384       Asm labels do not have this restriction.
 385
 386    3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
 387       applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
 388       new name is different, a warning issues and the name does not change.
 389
 390    4) The "source name" for #pragma redefine_extname is the DECL_NAME,
 391       *not* the DECL_ASSEMBLER_NAME.
 392
 393    5) If #pragma extern_prefix is in effect and a declaration occurs
 394       with an __asm__ name, the #pragma extern_prefix is silently
 395       ignored for that declaration.
 396
 397    6) If #pragma extern_prefix and #pragma redefine_extname apply to
 398       the same declaration, whichever triggered first wins, and a warning
 399       is issued.  (We would like to have #pragma redefine_extname always
 400       win, but it can appear either before or after the declaration, and
 401       if it appears afterward, we have no way of knowing whether a modified
 402       DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.)  */
 403
 404 static GTY(()) tree pending_redefine_extname;
 405
 406 static void handle_pragma_redefine_extname (cpp_reader *);
 407
 408 /* #pragma redefine_extname oldname newname */
 409 static void
 410 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
 411 {
 412   tree oldname, newname, decl, x;
 413   enum cpp_ttype t;
 414
 415   if (pragma_lex (&oldname) != CPP_NAME)
 416     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 417   if (pragma_lex (&newname) != CPP_NAME)
 418     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 419   t = pragma_lex (&x);
 420   if (t != CPP_EOF)
 421     warning (OPT_Wpragmas, "junk at end of %<#pragma redefine_extname%>");
 422
 423   if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
 424     {
 425       if (warn_unknown_pragmas > in_system_header)
 426         warning (OPT_Wunknown_pragmas,
 427                  "#pragma redefine_extname not supported on this target");
 428       return;
 429     }
 430
 431   decl = identifier_global_value (oldname);
 432   if (decl
 433       && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
 434       && (TREE_CODE (decl) == FUNCTION_DECL
 435           || TREE_CODE (decl) == VAR_DECL)
 436       && has_c_linkage (decl))
 437     {
 438       if (DECL_ASSEMBLER_NAME_SET_P (decl))
 439         {
 440           const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 441           name = targetm.strip_name_encoding (name);
 442
 443           if (strcmp (name, IDENTIFIER_POINTER (newname)))
 444             warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 445                      "conflict with previous rename");
 446         }
 447       else
 448         change_decl_assembler_name (decl, newname);
 449     }
 450   else
 451     /* We have to add this to the rename list even if there's already
 452        a global value that doesn't meet the above criteria, because in
 453        C++ "struct foo {...};" puts "foo" in the current namespace but
 454        does *not* conflict with a subsequent declaration of a function
 455        or variable foo.  See g++.dg/other/pragma-re-2.C.  */
 456     add_to_renaming_pragma_list (oldname, newname);
 457 }
 458
 459 /* This is called from here and from ia64.c.  */
 460 void
 461 add_to_renaming_pragma_list (tree oldname, tree newname)
 462 {
 463   tree previous = purpose_member (oldname, pending_redefine_extname);
 464   if (previous)
 465     {
 466       if (TREE_VALUE (previous) != newname)
 467         warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 468                  "conflict with previous #pragma redefine_extname");
 469       return;
 470     }
 471
 472   pending_redefine_extname
 473     = tree_cons (oldname, newname, pending_redefine_extname);
 474 }
 475
 476 static GTY(()) tree pragma_extern_prefix;
 477
 478 /* #pragma extern_prefix "prefix" */
 479 static void
 480 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
 481 {
 482   tree prefix, x;
 483   enum cpp_ttype t;
 484
 485   if (pragma_lex (&prefix) != CPP_STRING)
 486     GCC_BAD ("malformed #pragma extern_prefix, ignored");
 487   t = pragma_lex (&x);
 488   if (t != CPP_EOF)
 489     warning (OPT_Wpragmas, "junk at end of %<#pragma extern_prefix%>");
 490
 491   if (targetm.handle_pragma_extern_prefix)
 492     /* Note that the length includes the null terminator.  */
 493     pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
 494   else if (warn_unknown_pragmas > in_system_header)
 495     warning (OPT_Wunknown_pragmas,
 496              "#pragma extern_prefix not supported on this target");
 497 }
 498
 499 /* Hook from the front ends to apply the results of one of the preceding
 500    pragmas that rename variables.  */
 501
 502 tree
 503 maybe_apply_renaming_pragma (tree decl, tree asmname)
 504 {
 505   tree *p, t;
 506
 507   /* The renaming pragmas are only applied to declarations with
 508      external linkage.  */
 509   if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 510       || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
 511       || !has_c_linkage (decl))
 512     return asmname;
 513
 514   /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
 515      but we may warn about a rename that conflicts.  */
 516   if (DECL_ASSEMBLER_NAME_SET_P (decl))
 517     {
 518       const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 519       oldname = targetm.strip_name_encoding (oldname);
 520
 521       if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
 522           warning (OPT_Wpragmas, "asm declaration ignored due to "
 523                    "conflict with previous rename");
 524
 525       /* Take any pending redefine_extname off the list.  */
 526       for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 527         if (DECL_NAME (decl) == TREE_PURPOSE (t))
 528           {
 529             /* Only warn if there is a conflict.  */
 530             if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
 531               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 532                        "conflict with previous rename");
 533
 534             *p = TREE_CHAIN (t);
 535             break;
 536           }
 537       return 0;
 538     }
 539
 540   /* Find out if we have a pending #pragma redefine_extname.  */
 541   for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 542     if (DECL_NAME (decl) == TREE_PURPOSE (t))
 543       {
 544         tree newname = TREE_VALUE (t);
 545         *p = TREE_CHAIN (t);
 546
 547         /* If we already have an asmname, #pragma redefine_extname is
 548            ignored (with a warning if it conflicts).  */
 549         if (asmname)
 550           {
 551             if (strcmp (TREE_STRING_POINTER (asmname),
 552                         IDENTIFIER_POINTER (newname)) != 0)
 553               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 554                        "conflict with __asm__ declaration");
 555             return asmname;
 556           }
 557
 558         /* Otherwise we use what we've got; #pragma extern_prefix is
 559            silently ignored.  */
 560         return build_string (IDENTIFIER_LENGTH (newname),
 561                              IDENTIFIER_POINTER (newname));
 562       }
 563
 564   /* If we've got an asmname, #pragma extern_prefix is silently ignored.  */
 565   if (asmname)
 566     return asmname;
 567
 568   /* If #pragma extern_prefix is in effect, apply it.  */
 569   if (pragma_extern_prefix)
 570     {
 571       const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
 572       size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
 573
 574       const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
 575       size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
 576
 577       char *newname = (char *) alloca (plen + ilen + 1);
 578
 579       memcpy (newname,        prefix, plen);
 580       memcpy (newname + plen, id, ilen + 1);
 581
 582       return build_string (plen + ilen, newname);
 583     }
 584
 585   /* Nada.  */
 586   return 0;
 587 }
 588
 589
 590 #ifdef HANDLE_PRAGMA_VISIBILITY
 591 static void handle_pragma_visibility (cpp_reader *);
 592
 593 typedef enum symbol_visibility visibility;
 594 DEF_VEC_I (visibility);
 595 DEF_VEC_ALLOC_I (visibility, heap);
 596
 597 /* Sets the default visibility for symbols to something other than that
 598    specified on the command line.  */
 599 static void
 600 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
 601 {
 602   /* Form is #pragma GCC visibility push(hidden)|pop */
 603   tree x;
 604   enum cpp_ttype token;
 605   enum { bad, push, pop } action = bad;
 606   static VEC (visibility, heap) *visstack;
 607
 608   token = pragma_lex (&x);
 609   if (token == CPP_NAME)
 610     {
 611       const char *op = IDENTIFIER_POINTER (x);
 612       if (!strcmp (op, "push"))
 613         action = push;
 614       else if (!strcmp (op, "pop"))
 615         action = pop;
 616     }
 617   if (bad == action)
 618     GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
 619   else
 620     {
 621       if (pop == action)
 622         {
 623           if (!VEC_length (visibility, visstack))
 624             {
 625               GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>");
 626             }
 627           else
 628             {
 629               default_visibility = VEC_pop (visibility, visstack);
 630               visibility_options.inpragma
 631                 = VEC_length (visibility, visstack) != 0;
 632             }
 633         }
 634       else
 635         {
 636           if (pragma_lex (&x) != CPP_OPEN_PAREN)
 637             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 638           token = pragma_lex (&x);
 639           if (token != CPP_NAME)
 640             {
 641               GCC_BAD ("malformed #pragma GCC visibility push");
 642             }
 643           else
 644             {
 645               const char *str = IDENTIFIER_POINTER (x);
 646               VEC_safe_push (visibility, heap, visstack,
 647                              default_visibility);
 648               if (!strcmp (str, "default"))
 649                 default_visibility = VISIBILITY_DEFAULT;
 650               else if (!strcmp (str, "internal"))
 651                 default_visibility = VISIBILITY_INTERNAL;
 652               else if (!strcmp (str, "hidden"))
 653                 default_visibility = VISIBILITY_HIDDEN;
 654               else if (!strcmp (str, "protected"))
 655                 default_visibility = VISIBILITY_PROTECTED;
 656               else
 657                 {
 658                   GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
 659                 }
 660               visibility_options.inpragma = 1;
 661             }
 662           if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 663             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 664         }
 665     }
 666   if (pragma_lex (&x) != CPP_EOF)
 667     warning (OPT_Wpragmas, "junk at end of %<#pragma GCC visibility%>");
 668 }
 669
 670 #endif
 671
 672 static void
 673 handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))
 674 {
 675   const char *kind_string, *option_string;
 676   unsigned int option_index;
 677   enum cpp_ttype token;
 678   diagnostic_t kind;
 679   tree x;
 680
 681   if (cfun)
 682     {
 683       error ("#pragma GCC diagnostic not allowed inside functions");
 684       return;
 685     }
 686
 687   token = pragma_lex (&x);
 688   if (token != CPP_NAME)
 689     GCC_BAD ("missing [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 690   kind_string = IDENTIFIER_POINTER (x);
 691   if (strcmp (kind_string, "error") == 0)
 692     kind = DK_ERROR;
 693   else if (strcmp (kind_string, "warning") == 0)
 694     kind = DK_WARNING;
 695   else if (strcmp (kind_string, "ignored") == 0)
 696     kind = DK_IGNORED;
 697   else
 698     GCC_BAD ("expected [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 699
 700   token = pragma_lex (&x);
 701   if (token != CPP_STRING)
 702     GCC_BAD ("missing option after %<#pragma GCC diagnostic%> kind");
 703   option_string = TREE_STRING_POINTER (x);
 704   for (option_index = 0; option_index < cl_options_count; option_index++)
 705     if (strcmp (cl_options[option_index].opt_text, option_string) == 0)
 706       {
 707         /* This overrides -Werror, for example.  */
 708         diagnostic_classify_diagnostic (global_dc, option_index, kind);
 709         /* This makes sure the option is enabled, like -Wfoo would do.  */
 710         if (cl_options[option_index].var_type == CLVC_BOOLEAN
 711             && cl_options[option_index].flag_var
 712             && kind != DK_IGNORED)
 713             *(int *) cl_options[option_index].flag_var = 1;
 714         return;
 715       }
 716   GCC_BAD ("unknown option after %<#pragma GCC diagnostic%> kind");
 717 }
 718
 719 /* A vector of registered pragma callbacks.  */
 720
 721 DEF_VEC_O (pragma_handler);
 722 DEF_VEC_ALLOC_O (pragma_handler, heap);
 723
 724 static VEC(pragma_handler, heap) *registered_pragmas;
 725
 726 /* Front-end wrappers for pragma registration to avoid dragging
 727    cpplib.h in almost everywhere.  */
 728
 729 static void
 730 c_register_pragma_1 (const char *space, const char *name,
 731                      pragma_handler handler, bool allow_expansion)
 732 {
 733   unsigned id;
 734
 735   VEC_safe_push (pragma_handler, heap, registered_pragmas, &handler);
 736   id = VEC_length (pragma_handler, registered_pragmas);
 737   id += PRAGMA_FIRST_EXTERNAL - 1;
 738
 739   /* The C++ front end allocates 6 bits in cp_token; the C front end
 740      allocates 7 bits in c_token.  At present this is sufficient.  */
 741   gcc_assert (id < 64);
 742
 743   cpp_register_deferred_pragma (parse_in, space, name, id,
 744                                 allow_expansion, false);
 745 }
 746
 747 void
 748 c_register_pragma (const char *space, const char *name, pragma_handler handler)
 749 {
 750   c_register_pragma_1 (space, name, handler, false);
 751 }
 752
 753 void
 754 c_register_pragma_with_expansion (const char *space, const char *name,
 755                                   pragma_handler handler)
 756 {
 757   c_register_pragma_1 (space, name, handler, true);
 758 }
 759
 760 void
 761 c_invoke_pragma_handler (unsigned int id)
 762 {
 763   pragma_handler handler;
 764
 765   id -= PRAGMA_FIRST_EXTERNAL;
 766   handler = *VEC_index (pragma_handler, registered_pragmas, id);
 767
 768   handler (parse_in);
 769 }
 770
 771 /* Set up front-end pragmas.  */
 772 void
 773 init_pragma (void)
 774 {
 775   if (flag_openmp && !flag_preprocess_only)
 776     {
 777       struct omp_pragma_def { const char *name; unsigned int id; };
 778       static const struct omp_pragma_def omp_pragmas[] = {
 779         { "atomic", PRAGMA_OMP_ATOMIC },
 780         { "barrier", PRAGMA_OMP_BARRIER },
 781         { "critical", PRAGMA_OMP_CRITICAL },
 782         { "flush", PRAGMA_OMP_FLUSH },
 783         { "for", PRAGMA_OMP_FOR },
 784         { "master", PRAGMA_OMP_MASTER },
 785         { "ordered", PRAGMA_OMP_ORDERED },
 786         { "parallel", PRAGMA_OMP_PARALLEL },
 787         { "section", PRAGMA_OMP_SECTION },
 788         { "sections", PRAGMA_OMP_SECTIONS },
 789         { "single", PRAGMA_OMP_SINGLE },
 790         { "threadprivate", PRAGMA_OMP_THREADPRIVATE }
 791       };
 792
 793       const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
 794       int i;
 795
 796       for (i = 0; i < n_omp_pragmas; ++i)
 797         cpp_register_deferred_pragma (parse_in, "omp", omp_pragmas[i].name,
 798                                       omp_pragmas[i].id, true, true);
 799     }
 800
 801   cpp_register_deferred_pragma (parse_in, "GCC", "pch_preprocess",
 802                                 PRAGMA_GCC_PCH_PREPROCESS, false, false);
 803
 804 #ifdef HANDLE_PRAGMA_PACK
 805 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
 806   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 807 #else
 808   c_register_pragma (0, "pack", handle_pragma_pack);
 809 #endif
 810 #endif
 811 #ifdef HANDLE_PRAGMA_WEAK
 812   c_register_pragma (0, "weak", handle_pragma_weak);
 813 #endif
 814 #ifdef HANDLE_PRAGMA_VISIBILITY
 815   c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
 816 #endif
 817
 818   c_register_pragma ("GCC", "diagnostic", handle_pragma_diagnostic);
 819
 820   c_register_pragma_with_expansion (0, "redefine_extname", handle_pragma_redefine_extname);
 821   c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
 822
 823 #ifdef REGISTER_TARGET_PRAGMAS
 824   REGISTER_TARGET_PRAGMAS ();
 825 #endif
 826 }
 827
 828 #include "gt-c-pragma.h"