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       if (TREE_CODE (x) != INTEGER_CST)
 164         GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");
 165       align = TREE_INT_CST_LOW (x);
 166       action = set;
 167       if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 168         GCC_BAD ("malformed %<#pragma pack%> - ignored");
 169     }
 170   else if (token == CPP_NAME)
 171     {
 172 #define GCC_BAD_ACTION do { if (action != pop) \
 173           GCC_BAD ("malformed %<#pragma pack(push[, id][, <n>])%> - ignored"); \
 174         else \
 175           GCC_BAD ("malformed %<#pragma pack(pop[, id])%> - ignored"); \
 176         } while (0)
 177
 178       const char *op = IDENTIFIER_POINTER (x);
 179       if (!strcmp (op, "push"))
 180         action = push;
 181       else if (!strcmp (op, "pop"))
 182         action = pop;
 183       else
 184         GCC_BAD2 ("unknown action %qs for %<#pragma pack%> - ignored", op);
 185
 186       while ((token = pragma_lex (&x)) == CPP_COMMA)
 187         {
 188           token = pragma_lex (&x);
 189           if (token == CPP_NAME && id == 0)
 190             {
 191               id = x;
 192             }
 193           else if (token == CPP_NUMBER && action == push && align == -1)
 194             {
 195               if (TREE_CODE (x) != INTEGER_CST)
 196                 GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");
 197               align = TREE_INT_CST_LOW (x);
 198               if (align == -1)
 199                 action = set;
 200             }
 201           else
 202             GCC_BAD_ACTION;
 203         }
 204
 205       if (token != CPP_CLOSE_PAREN)
 206         GCC_BAD_ACTION;
 207 #undef GCC_BAD_ACTION
 208     }
 209   else
 210     GCC_BAD ("malformed %<#pragma pack%> - ignored");
 211
 212   if (pragma_lex (&x) != CPP_EOF)
 213     warning (OPT_Wpragmas, "junk at end of %<#pragma pack%>");
 214
 215   if (flag_pack_struct)
 216     GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored");
 217
 218   if (action != pop)
 219     switch (align)
 220       {
 221       case 0:
 222       case 1:
 223       case 2:
 224       case 4:
 225       case 8:
 226       case 16:
 227         align *= BITS_PER_UNIT;
 228         break;
 229       case -1:
 230         if (action == push)
 231           {
 232             align = maximum_field_alignment;
 233             break;
 234           }
 235       default:
 236         GCC_BAD2 ("alignment must be a small power of two, not %d", align);
 237       }
 238
 239   switch (action)
 240     {
 241     case set:   SET_GLOBAL_ALIGNMENT (align);  break;
 242     case push:  push_alignment (align, id);    break;
 243     case pop:   pop_alignment (id);            break;
 244     }
 245 }
 246 #endif  /* HANDLE_PRAGMA_PACK */
 247
 248 static GTY(()) tree pending_weaks;
 249
 250 #ifdef HANDLE_PRAGMA_WEAK
 251 static void apply_pragma_weak (tree, tree);
 252 static void handle_pragma_weak (cpp_reader *);
 253
 254 static void
 255 apply_pragma_weak (tree decl, tree value)
 256 {
 257   if (value)
 258     {
 259       value = build_string (IDENTIFIER_LENGTH (value),
 260                             IDENTIFIER_POINTER (value));
 261       decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
 262                                                build_tree_list (NULL, value)),
 263                        0);
 264     }
 265
 266   if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
 267       && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma.  */
 268       && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
 269     warning (OPT_Wpragmas, "applying #pragma weak %q+D after first use "
 270              "results in unspecified behavior", decl);
 271
 272   declare_weak (decl);
 273 }
 274
 275 void
 276 maybe_apply_pragma_weak (tree decl)
 277 {
 278   tree *p, t, id;
 279
 280   /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed.  */
 281
 282   /* No weak symbols pending, take the short-cut.  */
 283   if (!pending_weaks)
 284     return;
 285   /* If it's not visible outside this file, it doesn't matter whether
 286      it's weak.  */
 287   if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
 288     return;
 289   /* If it's not a function or a variable, it can't be weak.
 290      FIXME: what kinds of things are visible outside this file but
 291      aren't functions or variables?   Should this be an assert instead?  */
 292   if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 293     return;
 294
 295   id = DECL_ASSEMBLER_NAME (decl);
 296
 297   for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
 298     if (id == TREE_PURPOSE (t))
 299       {
 300         apply_pragma_weak (decl, TREE_VALUE (t));
 301         *p = TREE_CHAIN (t);
 302         break;
 303       }
 304 }
 305
 306 /* Process all "#pragma weak A = B" directives where we have not seen
 307    a decl for A.  */
 308 void
 309 maybe_apply_pending_pragma_weaks (void)
 310 {
 311   tree *p, t, alias_id, id, decl, *next;
 312
 313   for (p = &pending_weaks; (t = *p) ; p = next)
 314     {
 315       next = &TREE_CHAIN (t);
 316       alias_id = TREE_PURPOSE (t);
 317       id = TREE_VALUE (t);
 318
 319       if (TREE_VALUE (t) == NULL)
 320         continue;
 321
 322       decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
 323
 324       DECL_ARTIFICIAL (decl) = 1;
 325       TREE_PUBLIC (decl) = 1;
 326       DECL_EXTERNAL (decl) = 1;
 327       DECL_WEAK (decl) = 1;
 328
 329       assemble_alias (decl, id);
 330     }
 331 }
 332
 333 /* #pragma weak name [= value] */
 334 static void
 335 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
 336 {
 337   tree name, value, x, decl;
 338   enum cpp_ttype t;
 339
 340   value = 0;
 341
 342   if (pragma_lex (&name) != CPP_NAME)
 343     GCC_BAD ("malformed #pragma weak, ignored");
 344   t = pragma_lex (&x);
 345   if (t == CPP_EQ)
 346     {
 347       if (pragma_lex (&value) != CPP_NAME)
 348         GCC_BAD ("malformed #pragma weak, ignored");
 349       t = pragma_lex (&x);
 350     }
 351   if (t != CPP_EOF)
 352     warning (OPT_Wpragmas, "junk at end of %<#pragma weak%>");
 353
 354   decl = identifier_global_value (name);
 355   if (decl && DECL_P (decl))
 356     {
 357       apply_pragma_weak (decl, value);
 358       if (value)
 359         assemble_alias (decl, value);
 360     }
 361   else
 362     pending_weaks = tree_cons (name, value, pending_weaks);
 363 }
 364 #else
 365 void
 366 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
 367 {
 368 }
 369
 370 void
 371 maybe_apply_pending_pragma_weaks (void)
 372 {
 373 }
 374 #endif /* HANDLE_PRAGMA_WEAK */
 375
 376 /* GCC supports two #pragma directives for renaming the external
 377    symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
 378    compatibility with the Solaris and Tru64 system headers.  GCC also
 379    has its own notation for this, __asm__("name") annotations.
 380
 381    Corner cases of these features and their interaction:
 382
 383    1) Both pragmas silently apply only to declarations with external
 384       linkage (that is, TREE_PUBLIC || DECL_EXTERNAL).  Asm labels
 385       do not have this restriction.
 386
 387    2) In C++, both #pragmas silently apply only to extern "C" declarations.
 388       Asm labels do not have this restriction.
 389
 390    3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
 391       applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
 392       new name is different, a warning issues and the name does not change.
 393
 394    4) The "source name" for #pragma redefine_extname is the DECL_NAME,
 395       *not* the DECL_ASSEMBLER_NAME.
 396
 397    5) If #pragma extern_prefix is in effect and a declaration occurs
 398       with an __asm__ name, the #pragma extern_prefix is silently
 399       ignored for that declaration.
 400
 401    6) If #pragma extern_prefix and #pragma redefine_extname apply to
 402       the same declaration, whichever triggered first wins, and a warning
 403       is issued.  (We would like to have #pragma redefine_extname always
 404       win, but it can appear either before or after the declaration, and
 405       if it appears afterward, we have no way of knowing whether a modified
 406       DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.)  */
 407
 408 static GTY(()) tree pending_redefine_extname;
 409
 410 static void handle_pragma_redefine_extname (cpp_reader *);
 411
 412 /* #pragma redefine_extname oldname newname */
 413 static void
 414 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
 415 {
 416   tree oldname, newname, decl, x;
 417   enum cpp_ttype t;
 418
 419   if (pragma_lex (&oldname) != CPP_NAME)
 420     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 421   if (pragma_lex (&newname) != CPP_NAME)
 422     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 423   t = pragma_lex (&x);
 424   if (t != CPP_EOF)
 425     warning (OPT_Wpragmas, "junk at end of %<#pragma redefine_extname%>");
 426
 427   if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
 428     {
 429       if (warn_unknown_pragmas > in_system_header)
 430         warning (OPT_Wunknown_pragmas,
 431                  "#pragma redefine_extname not supported on this target");
 432       return;
 433     }
 434
 435   decl = identifier_global_value (oldname);
 436   if (decl
 437       && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
 438       && (TREE_CODE (decl) == FUNCTION_DECL
 439           || TREE_CODE (decl) == VAR_DECL)
 440       && has_c_linkage (decl))
 441     {
 442       if (DECL_ASSEMBLER_NAME_SET_P (decl))
 443         {
 444           const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 445           name = targetm.strip_name_encoding (name);
 446
 447           if (strcmp (name, IDENTIFIER_POINTER (newname)))
 448             warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 449                      "conflict with previous rename");
 450         }
 451       else
 452         change_decl_assembler_name (decl, newname);
 453     }
 454   else
 455     /* We have to add this to the rename list even if there's already
 456        a global value that doesn't meet the above criteria, because in
 457        C++ "struct foo {...};" puts "foo" in the current namespace but
 458        does *not* conflict with a subsequent declaration of a function
 459        or variable foo.  See g++.dg/other/pragma-re-2.C.  */
 460     add_to_renaming_pragma_list (oldname, newname);
 461 }
 462
 463 /* This is called from here and from ia64.c.  */
 464 void
 465 add_to_renaming_pragma_list (tree oldname, tree newname)
 466 {
 467   tree previous = purpose_member (oldname, pending_redefine_extname);
 468   if (previous)
 469     {
 470       if (TREE_VALUE (previous) != newname)
 471         warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 472                  "conflict with previous #pragma redefine_extname");
 473       return;
 474     }
 475
 476   pending_redefine_extname
 477     = tree_cons (oldname, newname, pending_redefine_extname);
 478 }
 479
 480 static GTY(()) tree pragma_extern_prefix;
 481
 482 /* #pragma extern_prefix "prefix" */
 483 static void
 484 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
 485 {
 486   tree prefix, x;
 487   enum cpp_ttype t;
 488
 489   if (pragma_lex (&prefix) != CPP_STRING)
 490     GCC_BAD ("malformed #pragma extern_prefix, ignored");
 491   t = pragma_lex (&x);
 492   if (t != CPP_EOF)
 493     warning (OPT_Wpragmas, "junk at end of %<#pragma extern_prefix%>");
 494
 495   if (targetm.handle_pragma_extern_prefix)
 496     /* Note that the length includes the null terminator.  */
 497     pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
 498   else if (warn_unknown_pragmas > in_system_header)
 499     warning (OPT_Wunknown_pragmas,
 500              "#pragma extern_prefix not supported on this target");
 501 }
 502
 503 /* Hook from the front ends to apply the results of one of the preceding
 504    pragmas that rename variables.  */
 505
 506 tree
 507 maybe_apply_renaming_pragma (tree decl, tree asmname)
 508 {
 509   tree *p, t;
 510
 511   /* The renaming pragmas are only applied to declarations with
 512      external linkage.  */
 513   if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 514       || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
 515       || !has_c_linkage (decl))
 516     return asmname;
 517
 518   /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
 519      but we may warn about a rename that conflicts.  */
 520   if (DECL_ASSEMBLER_NAME_SET_P (decl))
 521     {
 522       const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 523       oldname = targetm.strip_name_encoding (oldname);
 524
 525       if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
 526           warning (OPT_Wpragmas, "asm declaration ignored due to "
 527                    "conflict with previous rename");
 528
 529       /* Take any pending redefine_extname off the list.  */
 530       for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 531         if (DECL_NAME (decl) == TREE_PURPOSE (t))
 532           {
 533             /* Only warn if there is a conflict.  */
 534             if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
 535               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 536                        "conflict with previous rename");
 537
 538             *p = TREE_CHAIN (t);
 539             break;
 540           }
 541       return 0;
 542     }
 543
 544   /* Find out if we have a pending #pragma redefine_extname.  */
 545   for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 546     if (DECL_NAME (decl) == TREE_PURPOSE (t))
 547       {
 548         tree newname = TREE_VALUE (t);
 549         *p = TREE_CHAIN (t);
 550
 551         /* If we already have an asmname, #pragma redefine_extname is
 552            ignored (with a warning if it conflicts).  */
 553         if (asmname)
 554           {
 555             if (strcmp (TREE_STRING_POINTER (asmname),
 556                         IDENTIFIER_POINTER (newname)) != 0)
 557               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 558                        "conflict with __asm__ declaration");
 559             return asmname;
 560           }
 561
 562         /* Otherwise we use what we've got; #pragma extern_prefix is
 563            silently ignored.  */
 564         return build_string (IDENTIFIER_LENGTH (newname),
 565                              IDENTIFIER_POINTER (newname));
 566       }
 567
 568   /* If we've got an asmname, #pragma extern_prefix is silently ignored.  */
 569   if (asmname)
 570     return asmname;
 571
 572   /* If #pragma extern_prefix is in effect, apply it.  */
 573   if (pragma_extern_prefix)
 574     {
 575       const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
 576       size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
 577
 578       const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
 579       size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
 580
 581       char *newname = (char *) alloca (plen + ilen + 1);
 582
 583       memcpy (newname,        prefix, plen);
 584       memcpy (newname + plen, id, ilen + 1);
 585
 586       return build_string (plen + ilen, newname);
 587     }
 588
 589   /* Nada.  */
 590   return 0;
 591 }
 592
 593
 594 #ifdef HANDLE_PRAGMA_VISIBILITY
 595 static void handle_pragma_visibility (cpp_reader *);
 596
 597 typedef enum symbol_visibility visibility;
 598 DEF_VEC_I (visibility);
 599 DEF_VEC_ALLOC_I (visibility, heap);
 600 static VEC (visibility, heap) *visstack;
 601
 602 /* Push the visibility indicated by STR onto the top of the #pragma
 603    visibility stack.  */
 604
 605 void
 606 push_visibility (const char *str)
 607 {
 608   VEC_safe_push (visibility, heap, visstack,
 609                  default_visibility);
 610   if (!strcmp (str, "default"))
 611     default_visibility = VISIBILITY_DEFAULT;
 612   else if (!strcmp (str, "internal"))
 613     default_visibility = VISIBILITY_INTERNAL;
 614   else if (!strcmp (str, "hidden"))
 615     default_visibility = VISIBILITY_HIDDEN;
 616   else if (!strcmp (str, "protected"))
 617     default_visibility = VISIBILITY_PROTECTED;
 618   else
 619     GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
 620   visibility_options.inpragma = 1;
 621 }
 622
 623 /* Pop a level of the #pragma visibility stack.  */
 624
 625 void
 626 pop_visibility (void)
 627 {
 628   default_visibility = VEC_pop (visibility, visstack);
 629   visibility_options.inpragma
 630     = VEC_length (visibility, visstack) != 0;
 631 }
 632
 633 /* Sets the default visibility for symbols to something other than that
 634    specified on the command line.  */
 635
 636 static void
 637 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
 638 {
 639   /* Form is #pragma GCC visibility push(hidden)|pop */
 640   tree x;
 641   enum cpp_ttype token;
 642   enum { bad, push, pop } action = bad;
 643
 644   token = pragma_lex (&x);
 645   if (token == CPP_NAME)
 646     {
 647       const char *op = IDENTIFIER_POINTER (x);
 648       if (!strcmp (op, "push"))
 649         action = push;
 650       else if (!strcmp (op, "pop"))
 651         action = pop;
 652     }
 653   if (bad == action)
 654     GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
 655   else
 656     {
 657       if (pop == action)
 658         {
 659           if (!VEC_length (visibility, visstack))
 660             GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>");
 661           else
 662             pop_visibility ();
 663         }
 664       else
 665         {
 666           if (pragma_lex (&x) != CPP_OPEN_PAREN)
 667             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 668           token = pragma_lex (&x);
 669           if (token != CPP_NAME)
 670             GCC_BAD ("malformed #pragma GCC visibility push");
 671           else
 672             push_visibility (IDENTIFIER_POINTER (x));
 673           if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 674             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 675         }
 676     }
 677   if (pragma_lex (&x) != CPP_EOF)
 678     warning (OPT_Wpragmas, "junk at end of %<#pragma GCC visibility%>");
 679 }
 680
 681 #endif
 682
 683 static void
 684 handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))
 685 {
 686   const char *kind_string, *option_string;
 687   unsigned int option_index;
 688   enum cpp_ttype token;
 689   diagnostic_t kind;
 690   tree x;
 691
 692   if (cfun)
 693     {
 694       error ("#pragma GCC diagnostic not allowed inside functions");
 695       return;
 696     }
 697
 698   token = pragma_lex (&x);
 699   if (token != CPP_NAME)
 700     GCC_BAD ("missing [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 701   kind_string = IDENTIFIER_POINTER (x);
 702   if (strcmp (kind_string, "error") == 0)
 703     kind = DK_ERROR;
 704   else if (strcmp (kind_string, "warning") == 0)
 705     kind = DK_WARNING;
 706   else if (strcmp (kind_string, "ignored") == 0)
 707     kind = DK_IGNORED;
 708   else
 709     GCC_BAD ("expected [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 710
 711   token = pragma_lex (&x);
 712   if (token != CPP_STRING)
 713     GCC_BAD ("missing option after %<#pragma GCC diagnostic%> kind");
 714   option_string = TREE_STRING_POINTER (x);
 715   for (option_index = 0; option_index < cl_options_count; option_index++)
 716     if (strcmp (cl_options[option_index].opt_text, option_string) == 0)
 717       {
 718         /* This overrides -Werror, for example.  */
 719         diagnostic_classify_diagnostic (global_dc, option_index, kind);
 720         /* This makes sure the option is enabled, like -Wfoo would do.  */
 721         if (cl_options[option_index].var_type == CLVC_BOOLEAN
 722             && cl_options[option_index].flag_var
 723             && kind != DK_IGNORED)
 724             *(int *) cl_options[option_index].flag_var = 1;
 725         return;
 726       }
 727   GCC_BAD ("unknown option after %<#pragma GCC diagnostic%> kind");
 728 }
 729
 730 /* A vector of registered pragma callbacks.  */
 731
 732 DEF_VEC_O (pragma_handler);
 733 DEF_VEC_ALLOC_O (pragma_handler, heap);
 734
 735 static VEC(pragma_handler, heap) *registered_pragmas;
 736
 737 /* Front-end wrappers for pragma registration to avoid dragging
 738    cpplib.h in almost everywhere.  */
 739
 740 static void
 741 c_register_pragma_1 (const char *space, const char *name,
 742                      pragma_handler handler, bool allow_expansion)
 743 {
 744   unsigned id;
 745
 746   VEC_safe_push (pragma_handler, heap, registered_pragmas, &handler);
 747   id = VEC_length (pragma_handler, registered_pragmas);
 748   id += PRAGMA_FIRST_EXTERNAL - 1;
 749
 750   /* The C++ front end allocates 6 bits in cp_token; the C front end
 751      allocates 7 bits in c_token.  At present this is sufficient.  */
 752   gcc_assert (id < 64);
 753
 754   cpp_register_deferred_pragma (parse_in, space, name, id,
 755                                 allow_expansion, false);
 756 }
 757
 758 void
 759 c_register_pragma (const char *space, const char *name, pragma_handler handler)
 760 {
 761   c_register_pragma_1 (space, name, handler, false);
 762 }
 763
 764 void
 765 c_register_pragma_with_expansion (const char *space, const char *name,
 766                                   pragma_handler handler)
 767 {
 768   c_register_pragma_1 (space, name, handler, true);
 769 }
 770
 771 void
 772 c_invoke_pragma_handler (unsigned int id)
 773 {
 774   pragma_handler handler;
 775
 776   id -= PRAGMA_FIRST_EXTERNAL;
 777   handler = *VEC_index (pragma_handler, registered_pragmas, id);
 778
 779   handler (parse_in);
 780 }
 781
 782 /* Set up front-end pragmas.  */
 783 void
 784 init_pragma (void)
 785 {
 786   if (flag_openmp && !flag_preprocess_only)
 787     {
 788       struct omp_pragma_def { const char *name; unsigned int id; };
 789       static const struct omp_pragma_def omp_pragmas[] = {
 790         { "atomic", PRAGMA_OMP_ATOMIC },
 791         { "barrier", PRAGMA_OMP_BARRIER },
 792         { "critical", PRAGMA_OMP_CRITICAL },
 793         { "flush", PRAGMA_OMP_FLUSH },
 794         { "for", PRAGMA_OMP_FOR },
 795         { "master", PRAGMA_OMP_MASTER },
 796         { "ordered", PRAGMA_OMP_ORDERED },
 797         { "parallel", PRAGMA_OMP_PARALLEL },
 798         { "section", PRAGMA_OMP_SECTION },
 799         { "sections", PRAGMA_OMP_SECTIONS },
 800         { "single", PRAGMA_OMP_SINGLE },
 801         { "threadprivate", PRAGMA_OMP_THREADPRIVATE }
 802       };
 803
 804       const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
 805       int i;
 806
 807       for (i = 0; i < n_omp_pragmas; ++i)
 808         cpp_register_deferred_pragma (parse_in, "omp", omp_pragmas[i].name,
 809                                       omp_pragmas[i].id, true, true);
 810     }
 811
 812   cpp_register_deferred_pragma (parse_in, "GCC", "pch_preprocess",
 813                                 PRAGMA_GCC_PCH_PREPROCESS, false, false);
 814
 815 #ifdef HANDLE_PRAGMA_PACK
 816 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
 817   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 818 #else
 819   c_register_pragma (0, "pack", handle_pragma_pack);
 820 #endif
 821 #endif
 822 #ifdef HANDLE_PRAGMA_WEAK
 823   c_register_pragma (0, "weak", handle_pragma_weak);
 824 #endif
 825 #ifdef HANDLE_PRAGMA_VISIBILITY
 826   c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
 827 #endif
 828
 829   c_register_pragma ("GCC", "diagnostic", handle_pragma_diagnostic);
 830
 831   c_register_pragma_with_expansion (0, "redefine_extname", handle_pragma_redefine_extname);
 832   c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
 833
 834 #ifdef REGISTER_TARGET_PRAGMAS
 835   REGISTER_TARGET_PRAGMAS ();
 836 #endif
 837 }
 838
 839 #include "gt-c-pragma.h"