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 struct def_pragma_macro_value GTY(())
 249 {
 250   struct def_pragma_macro_value *prev;
 251   cpp_macro *value;
 252 };
 253
 254 struct def_pragma_macro GTY(())
 255 {
 256   hashval_t hash;
 257   const char *name;
 258   struct def_pragma_macro_value value;
 259 };
 260
 261 static GTY((param_is (struct def_pragma_macro))) htab_t pushed_macro_table;
 262
 263 #ifdef HANDLE_PRAGMA_PUSH_POP_MACRO
 264 /* Hash table control functions for pushed_macro_table.  */
 265 static hashval_t
 266 dpm_hash (const void *p)
 267 {
 268   return ((const struct def_pragma_macro *)p)->hash;
 269 }
 270
 271 static int
 272 dpm_eq (const void *pa, const void *pb)
 273 {
 274   const struct def_pragma_macro *a = pa, *b = pb;
 275   return a->hash == b->hash && strcmp (a->name, b->name) == 0;
 276 }
 277
 278 /* #pragma push_macro("MACRO_NAME")
 279    #pragma pop_macro("MACRO_NAME") */
 280
 281 static void
 282 handle_pragma_push_macro (cpp_reader *reader)
 283 {
 284   tree x, id = 0;
 285   enum cpp_ttype token;
 286   struct def_pragma_macro dummy, *c;
 287   const char *macroname;
 288   void **slot;
 289
 290   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 291     GCC_BAD ("missing %<(%> after %<#pragma push_macro%> - ignored");
 292
 293   token = pragma_lex (&id);
 294
 295   /* Silently ignore */
 296   if (token == CPP_CLOSE_PAREN)
 297     return;
 298   if (token != CPP_STRING)
 299     GCC_BAD ("invalid constant in %<#pragma push_macro%> - ignored");
 300
 301   if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 302     GCC_BAD ("missing %<)%> after %<#pragma push_macro%> - ignored");
 303
 304   if (pragma_lex (&x) != CPP_EOF)
 305     warning (OPT_Wpragmas, "junk at end of %<#pragma push_macro%>");
 306
 307   /* Check for empty string, and silently ignore.  */
 308   if (TREE_STRING_LENGTH (id) < 1)
 309     return;
 310   macroname = TREE_STRING_POINTER (id);
 311
 312   if (pushed_macro_table == NULL)
 313     pushed_macro_table = htab_create_ggc (15, dpm_hash, dpm_eq, 0);
 314
 315   dummy.hash = htab_hash_string (macroname);
 316   dummy.name = macroname;
 317   slot = htab_find_slot_with_hash (pushed_macro_table, &dummy,
 318                                    dummy.hash, INSERT);
 319   c = *slot;
 320   if (c == NULL)
 321     {
 322       *slot = c = ggc_alloc (sizeof (struct def_pragma_macro));
 323       c->hash = dummy.hash;
 324       c->name = ggc_alloc_string (macroname, TREE_STRING_LENGTH (id) - 1);
 325       c->value.prev = NULL;
 326     }
 327   else
 328     {
 329       struct def_pragma_macro_value *v;
 330       v = ggc_alloc (sizeof (struct def_pragma_macro_value));
 331       *v = c->value;
 332       c->value.prev = v;
 333     }
 334
 335   c->value.value = cpp_push_definition (reader, macroname);
 336 }
 337
 338 static void
 339 handle_pragma_pop_macro (cpp_reader *reader)
 340 {
 341   tree x, id = 0;
 342   enum cpp_ttype token;
 343   struct def_pragma_macro dummy, *c;
 344   const char *macroname;
 345   void **slot;
 346
 347   if (pragma_lex (&x) != CPP_OPEN_PAREN)
 348     GCC_BAD ("missing %<(%> after %<#pragma pop_macro%> - ignored");
 349
 350   token = pragma_lex (&id);
 351
 352   /* Silently ignore */
 353   if (token == CPP_CLOSE_PAREN)
 354     return;
 355   if (token != CPP_STRING)
 356     GCC_BAD ("invalid constant in %<#pragma pop_macro%> - ignored");
 357
 358   if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 359     GCC_BAD ("missing %<)%> after %<#pragma pop_macro%> - ignored");
 360
 361   if (pragma_lex (&x) != CPP_EOF)
 362     warning (OPT_Wpragmas, "junk at end of %<#pragma pop_macro%>");
 363
 364   /* Check for empty string, and silently ignore.  */
 365   if (TREE_STRING_LENGTH (id) < 1)
 366     return;
 367   macroname = TREE_STRING_POINTER (id);
 368
 369   dummy.hash = htab_hash_string (macroname);
 370   dummy.name = macroname;
 371   slot = htab_find_slot_with_hash (pushed_macro_table, &dummy,
 372                                    dummy.hash, NO_INSERT);
 373   if (slot == NULL)
 374     return;
 375   c = *slot;
 376
 377   cpp_pop_definition (reader, c->name, c->value.value);
 378
 379   if (c->value.prev)
 380     c->value = *c->value.prev;
 381   else
 382     htab_clear_slot (pushed_macro_table, slot);
 383 }
 384 #endif /* HANDLE_PRAGMA_PUSH_POP_MACRO */
 385
 386 static GTY(()) tree pending_weaks;
 387
 388 #ifdef HANDLE_PRAGMA_WEAK
 389 static void apply_pragma_weak (tree, tree);
 390 static void handle_pragma_weak (cpp_reader *);
 391
 392 static void
 393 apply_pragma_weak (tree decl, tree value)
 394 {
 395   if (value)
 396     {
 397       value = build_string (IDENTIFIER_LENGTH (value),
 398                             IDENTIFIER_POINTER (value));
 399       decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
 400                                                build_tree_list (NULL, value)),
 401                        0);
 402     }
 403
 404   if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
 405       && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma.  */
 406       && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
 407     warning (OPT_Wpragmas, "applying #pragma weak %q+D after first use "
 408              "results in unspecified behavior", decl);
 409
 410   declare_weak (decl);
 411 }
 412
 413 void
 414 maybe_apply_pragma_weak (tree decl)
 415 {
 416   tree *p, t, id;
 417
 418   /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed.  */
 419
 420   /* No weak symbols pending, take the short-cut.  */
 421   if (!pending_weaks)
 422     return;
 423   /* If it's not visible outside this file, it doesn't matter whether
 424      it's weak.  */
 425   if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
 426     return;
 427   /* If it's not a function or a variable, it can't be weak.
 428      FIXME: what kinds of things are visible outside this file but
 429      aren't functions or variables?   Should this be an assert instead?  */
 430   if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 431     return;
 432
 433   id = DECL_ASSEMBLER_NAME (decl);
 434
 435   for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
 436     if (id == TREE_PURPOSE (t))
 437       {
 438         apply_pragma_weak (decl, TREE_VALUE (t));
 439         *p = TREE_CHAIN (t);
 440         break;
 441       }
 442 }
 443
 444 /* Process all "#pragma weak A = B" directives where we have not seen
 445    a decl for A.  */
 446 void
 447 maybe_apply_pending_pragma_weaks (void)
 448 {
 449   tree *p, t, alias_id, id, decl, *next;
 450
 451   for (p = &pending_weaks; (t = *p) ; p = next)
 452     {
 453       next = &TREE_CHAIN (t);
 454       alias_id = TREE_PURPOSE (t);
 455       id = TREE_VALUE (t);
 456
 457       if (TREE_VALUE (t) == NULL)
 458         continue;
 459
 460       decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
 461
 462       DECL_ARTIFICIAL (decl) = 1;
 463       TREE_PUBLIC (decl) = 1;
 464       DECL_EXTERNAL (decl) = 1;
 465       DECL_WEAK (decl) = 1;
 466
 467       assemble_alias (decl, id);
 468     }
 469 }
 470
 471 /* #pragma weak name [= value] */
 472 static void
 473 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
 474 {
 475   tree name, value, x, decl;
 476   enum cpp_ttype t;
 477
 478   value = 0;
 479
 480   if (pragma_lex (&name) != CPP_NAME)
 481     GCC_BAD ("malformed #pragma weak, ignored");
 482   t = pragma_lex (&x);
 483   if (t == CPP_EQ)
 484     {
 485       if (pragma_lex (&value) != CPP_NAME)
 486         GCC_BAD ("malformed #pragma weak, ignored");
 487       t = pragma_lex (&x);
 488     }
 489   if (t != CPP_EOF)
 490     warning (OPT_Wpragmas, "junk at end of %<#pragma weak%>");
 491
 492   decl = identifier_global_value (name);
 493   if (decl && DECL_P (decl))
 494     {
 495       apply_pragma_weak (decl, value);
 496       if (value)
 497         assemble_alias (decl, value);
 498     }
 499   else
 500     pending_weaks = tree_cons (name, value, pending_weaks);
 501 }
 502 #else
 503 void
 504 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
 505 {
 506 }
 507
 508 void
 509 maybe_apply_pending_pragma_weaks (void)
 510 {
 511 }
 512 #endif /* HANDLE_PRAGMA_WEAK */
 513
 514 /* GCC supports two #pragma directives for renaming the external
 515    symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
 516    compatibility with the Solaris and Tru64 system headers.  GCC also
 517    has its own notation for this, __asm__("name") annotations.
 518
 519    Corner cases of these features and their interaction:
 520
 521    1) Both pragmas silently apply only to declarations with external
 522       linkage (that is, TREE_PUBLIC || DECL_EXTERNAL).  Asm labels
 523       do not have this restriction.
 524
 525    2) In C++, both #pragmas silently apply only to extern "C" declarations.
 526       Asm labels do not have this restriction.
 527
 528    3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
 529       applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
 530       new name is different, a warning issues and the name does not change.
 531
 532    4) The "source name" for #pragma redefine_extname is the DECL_NAME,
 533       *not* the DECL_ASSEMBLER_NAME.
 534
 535    5) If #pragma extern_prefix is in effect and a declaration occurs
 536       with an __asm__ name, the #pragma extern_prefix is silently
 537       ignored for that declaration.
 538
 539    6) If #pragma extern_prefix and #pragma redefine_extname apply to
 540       the same declaration, whichever triggered first wins, and a warning
 541       is issued.  (We would like to have #pragma redefine_extname always
 542       win, but it can appear either before or after the declaration, and
 543       if it appears afterward, we have no way of knowing whether a modified
 544       DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.)  */
 545
 546 static GTY(()) tree pending_redefine_extname;
 547
 548 static void handle_pragma_redefine_extname (cpp_reader *);
 549
 550 /* #pragma redefine_extname oldname newname */
 551 static void
 552 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
 553 {
 554   tree oldname, newname, decl, x;
 555   enum cpp_ttype t;
 556
 557   if (pragma_lex (&oldname) != CPP_NAME)
 558     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 559   if (pragma_lex (&newname) != CPP_NAME)
 560     GCC_BAD ("malformed #pragma redefine_extname, ignored");
 561   t = pragma_lex (&x);
 562   if (t != CPP_EOF)
 563     warning (OPT_Wpragmas, "junk at end of %<#pragma redefine_extname%>");
 564
 565   if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
 566     {
 567       if (warn_unknown_pragmas > in_system_header)
 568         warning (OPT_Wunknown_pragmas,
 569                  "#pragma redefine_extname not supported on this target");
 570       return;
 571     }
 572
 573   decl = identifier_global_value (oldname);
 574   if (decl
 575       && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
 576       && (TREE_CODE (decl) == FUNCTION_DECL
 577           || TREE_CODE (decl) == VAR_DECL)
 578       && has_c_linkage (decl))
 579     {
 580       if (DECL_ASSEMBLER_NAME_SET_P (decl))
 581         {
 582           const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 583           name = targetm.strip_name_encoding (name);
 584
 585           if (strcmp (name, IDENTIFIER_POINTER (newname)))
 586             warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 587                      "conflict with previous rename");
 588         }
 589       else
 590         change_decl_assembler_name (decl, newname);
 591     }
 592   else
 593     /* We have to add this to the rename list even if there's already
 594        a global value that doesn't meet the above criteria, because in
 595        C++ "struct foo {...};" puts "foo" in the current namespace but
 596        does *not* conflict with a subsequent declaration of a function
 597        or variable foo.  See g++.dg/other/pragma-re-2.C.  */
 598     add_to_renaming_pragma_list (oldname, newname);
 599 }
 600
 601 /* This is called from here and from ia64.c.  */
 602 void
 603 add_to_renaming_pragma_list (tree oldname, tree newname)
 604 {
 605   tree previous = purpose_member (oldname, pending_redefine_extname);
 606   if (previous)
 607     {
 608       if (TREE_VALUE (previous) != newname)
 609         warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 610                  "conflict with previous #pragma redefine_extname");
 611       return;
 612     }
 613
 614   pending_redefine_extname
 615     = tree_cons (oldname, newname, pending_redefine_extname);
 616 }
 617
 618 static GTY(()) tree pragma_extern_prefix;
 619
 620 /* #pragma extern_prefix "prefix" */
 621 static void
 622 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
 623 {
 624   tree prefix, x;
 625   enum cpp_ttype t;
 626
 627   if (pragma_lex (&prefix) != CPP_STRING)
 628     GCC_BAD ("malformed #pragma extern_prefix, ignored");
 629   t = pragma_lex (&x);
 630   if (t != CPP_EOF)
 631     warning (OPT_Wpragmas, "junk at end of %<#pragma extern_prefix%>");
 632
 633   if (targetm.handle_pragma_extern_prefix)
 634     /* Note that the length includes the null terminator.  */
 635     pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
 636   else if (warn_unknown_pragmas > in_system_header)
 637     warning (OPT_Wunknown_pragmas,
 638              "#pragma extern_prefix not supported on this target");
 639 }
 640
 641 /* Hook from the front ends to apply the results of one of the preceding
 642    pragmas that rename variables.  */
 643
 644 tree
 645 maybe_apply_renaming_pragma (tree decl, tree asmname)
 646 {
 647   tree *p, t;
 648
 649   /* The renaming pragmas are only applied to declarations with
 650      external linkage.  */
 651   if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
 652       || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
 653       || !has_c_linkage (decl))
 654     return asmname;
 655
 656   /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
 657      but we may warn about a rename that conflicts.  */
 658   if (DECL_ASSEMBLER_NAME_SET_P (decl))
 659     {
 660       const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 661       oldname = targetm.strip_name_encoding (oldname);
 662
 663       if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
 664           warning (OPT_Wpragmas, "asm declaration ignored due to "
 665                    "conflict with previous rename");
 666
 667       /* Take any pending redefine_extname off the list.  */
 668       for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 669         if (DECL_NAME (decl) == TREE_PURPOSE (t))
 670           {
 671             /* Only warn if there is a conflict.  */
 672             if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
 673               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 674                        "conflict with previous rename");
 675
 676             *p = TREE_CHAIN (t);
 677             break;
 678           }
 679       return 0;
 680     }
 681
 682   /* Find out if we have a pending #pragma redefine_extname.  */
 683   for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
 684     if (DECL_NAME (decl) == TREE_PURPOSE (t))
 685       {
 686         tree newname = TREE_VALUE (t);
 687         *p = TREE_CHAIN (t);
 688
 689         /* If we already have an asmname, #pragma redefine_extname is
 690            ignored (with a warning if it conflicts).  */
 691         if (asmname)
 692           {
 693             if (strcmp (TREE_STRING_POINTER (asmname),
 694                         IDENTIFIER_POINTER (newname)) != 0)
 695               warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
 696                        "conflict with __asm__ declaration");
 697             return asmname;
 698           }
 699
 700         /* Otherwise we use what we've got; #pragma extern_prefix is
 701            silently ignored.  */
 702         return build_string (IDENTIFIER_LENGTH (newname),
 703                              IDENTIFIER_POINTER (newname));
 704       }
 705
 706   /* If we've got an asmname, #pragma extern_prefix is silently ignored.  */
 707   if (asmname)
 708     return asmname;
 709
 710   /* If #pragma extern_prefix is in effect, apply it.  */
 711   if (pragma_extern_prefix)
 712     {
 713       const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
 714       size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
 715
 716       const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
 717       size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
 718
 719       char *newname = (char *) alloca (plen + ilen + 1);
 720
 721       memcpy (newname,        prefix, plen);
 722       memcpy (newname + plen, id, ilen + 1);
 723
 724       return build_string (plen + ilen, newname);
 725     }
 726
 727   /* Nada.  */
 728   return 0;
 729 }
 730
 731
 732 #ifdef HANDLE_PRAGMA_VISIBILITY
 733 static void handle_pragma_visibility (cpp_reader *);
 734
 735 typedef enum symbol_visibility visibility;
 736 DEF_VEC_I (visibility);
 737 DEF_VEC_ALLOC_I (visibility, heap);
 738 static VEC (visibility, heap) *visstack;
 739
 740 /* Push the visibility indicated by STR onto the top of the #pragma
 741    visibility stack.  */
 742
 743 void
 744 push_visibility (const char *str)
 745 {
 746   VEC_safe_push (visibility, heap, visstack,
 747                  default_visibility);
 748   if (!strcmp (str, "default"))
 749     default_visibility = VISIBILITY_DEFAULT;
 750   else if (!strcmp (str, "internal"))
 751     default_visibility = VISIBILITY_INTERNAL;
 752   else if (!strcmp (str, "hidden"))
 753     default_visibility = VISIBILITY_HIDDEN;
 754   else if (!strcmp (str, "protected"))
 755     default_visibility = VISIBILITY_PROTECTED;
 756   else
 757     GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
 758   visibility_options.inpragma = 1;
 759 }
 760
 761 /* Pop a level of the #pragma visibility stack.  */
 762
 763 void
 764 pop_visibility (void)
 765 {
 766   default_visibility = VEC_pop (visibility, visstack);
 767   visibility_options.inpragma
 768     = VEC_length (visibility, visstack) != 0;
 769 }
 770
 771 /* Sets the default visibility for symbols to something other than that
 772    specified on the command line.  */
 773
 774 static void
 775 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
 776 {
 777   /* Form is #pragma GCC visibility push(hidden)|pop */
 778   tree x;
 779   enum cpp_ttype token;
 780   enum { bad, push, pop } action = bad;
 781
 782   token = pragma_lex (&x);
 783   if (token == CPP_NAME)
 784     {
 785       const char *op = IDENTIFIER_POINTER (x);
 786       if (!strcmp (op, "push"))
 787         action = push;
 788       else if (!strcmp (op, "pop"))
 789         action = pop;
 790     }
 791   if (bad == action)
 792     GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
 793   else
 794     {
 795       if (pop == action)
 796         {
 797           if (!VEC_length (visibility, visstack))
 798             GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>");
 799           else
 800             pop_visibility ();
 801         }
 802       else
 803         {
 804           if (pragma_lex (&x) != CPP_OPEN_PAREN)
 805             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 806           token = pragma_lex (&x);
 807           if (token != CPP_NAME)
 808             GCC_BAD ("malformed #pragma GCC visibility push");
 809           else
 810             push_visibility (IDENTIFIER_POINTER (x));
 811           if (pragma_lex (&x) != CPP_CLOSE_PAREN)
 812             GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
 813         }
 814     }
 815   if (pragma_lex (&x) != CPP_EOF)
 816     warning (OPT_Wpragmas, "junk at end of %<#pragma GCC visibility%>");
 817 }
 818
 819 #endif
 820
 821 static void
 822 handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))
 823 {
 824   const char *kind_string, *option_string;
 825   unsigned int option_index;
 826   enum cpp_ttype token;
 827   diagnostic_t kind;
 828   tree x;
 829
 830   if (cfun)
 831     {
 832       error ("#pragma GCC diagnostic not allowed inside functions");
 833       return;
 834     }
 835
 836   token = pragma_lex (&x);
 837   if (token != CPP_NAME)
 838     GCC_BAD ("missing [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 839   kind_string = IDENTIFIER_POINTER (x);
 840   if (strcmp (kind_string, "error") == 0)
 841     kind = DK_ERROR;
 842   else if (strcmp (kind_string, "warning") == 0)
 843     kind = DK_WARNING;
 844   else if (strcmp (kind_string, "ignored") == 0)
 845     kind = DK_IGNORED;
 846   else
 847     GCC_BAD ("expected [error|warning|ignored] after %<#pragma GCC diagnostic%>");
 848
 849   token = pragma_lex (&x);
 850   if (token != CPP_STRING)
 851     GCC_BAD ("missing option after %<#pragma GCC diagnostic%> kind");
 852   option_string = TREE_STRING_POINTER (x);
 853   for (option_index = 0; option_index < cl_options_count; option_index++)
 854     if (strcmp (cl_options[option_index].opt_text, option_string) == 0)
 855       {
 856         /* This overrides -Werror, for example.  */
 857         diagnostic_classify_diagnostic (global_dc, option_index, kind);
 858         /* This makes sure the option is enabled, like -Wfoo would do.  */
 859         if (cl_options[option_index].var_type == CLVC_BOOLEAN
 860             && cl_options[option_index].flag_var
 861             && kind != DK_IGNORED)
 862             *(int *) cl_options[option_index].flag_var = 1;
 863         return;
 864       }
 865   GCC_BAD ("unknown option after %<#pragma GCC diagnostic%> kind");
 866 }
 867
 868 /* A vector of registered pragma callbacks.  */
 869
 870 DEF_VEC_O (pragma_handler);
 871 DEF_VEC_ALLOC_O (pragma_handler, heap);
 872
 873 static VEC(pragma_handler, heap) *registered_pragmas;
 874
 875 /* Front-end wrappers for pragma registration to avoid dragging
 876    cpplib.h in almost everywhere.  */
 877
 878 static void
 879 c_register_pragma_1 (const char *space, const char *name,
 880                      pragma_handler handler, bool allow_expansion)
 881 {
 882   unsigned id;
 883
 884   VEC_safe_push (pragma_handler, heap, registered_pragmas, &handler);
 885   id = VEC_length (pragma_handler, registered_pragmas);
 886   id += PRAGMA_FIRST_EXTERNAL - 1;
 887
 888   /* The C++ front end allocates 6 bits in cp_token; the C front end
 889      allocates 7 bits in c_token.  At present this is sufficient.  */
 890   gcc_assert (id < 64);
 891
 892   cpp_register_deferred_pragma (parse_in, space, name, id,
 893                                 allow_expansion, false);
 894 }
 895
 896 void
 897 c_register_pragma (const char *space, const char *name, pragma_handler handler)
 898 {
 899   c_register_pragma_1 (space, name, handler, false);
 900 }
 901
 902 void
 903 c_register_pragma_with_expansion (const char *space, const char *name,
 904                                   pragma_handler handler)
 905 {
 906   c_register_pragma_1 (space, name, handler, true);
 907 }
 908
 909 void
 910 c_invoke_pragma_handler (unsigned int id)
 911 {
 912   pragma_handler handler;
 913
 914   id -= PRAGMA_FIRST_EXTERNAL;
 915   handler = *VEC_index (pragma_handler, registered_pragmas, id);
 916
 917   handler (parse_in);
 918 }
 919
 920 /* Set up front-end pragmas.  */
 921 void
 922 init_pragma (void)
 923 {
 924   if (flag_openmp && !flag_preprocess_only)
 925     {
 926       struct omp_pragma_def { const char *name; unsigned int id; };
 927       static const struct omp_pragma_def omp_pragmas[] = {
 928         { "atomic", PRAGMA_OMP_ATOMIC },
 929         { "barrier", PRAGMA_OMP_BARRIER },
 930         { "critical", PRAGMA_OMP_CRITICAL },
 931         { "flush", PRAGMA_OMP_FLUSH },
 932         { "for", PRAGMA_OMP_FOR },
 933         { "master", PRAGMA_OMP_MASTER },
 934         { "ordered", PRAGMA_OMP_ORDERED },
 935         { "parallel", PRAGMA_OMP_PARALLEL },
 936         { "section", PRAGMA_OMP_SECTION },
 937         { "sections", PRAGMA_OMP_SECTIONS },
 938         { "single", PRAGMA_OMP_SINGLE },
 939         { "threadprivate", PRAGMA_OMP_THREADPRIVATE }
 940       };
 941
 942       const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
 943       int i;
 944
 945       for (i = 0; i < n_omp_pragmas; ++i)
 946         cpp_register_deferred_pragma (parse_in, "omp", omp_pragmas[i].name,
 947                                       omp_pragmas[i].id, true, true);
 948     }
 949
 950   cpp_register_deferred_pragma (parse_in, "GCC", "pch_preprocess",
 951                                 PRAGMA_GCC_PCH_PREPROCESS, false, false);
 952
 953 #ifdef HANDLE_PRAGMA_PACK
 954 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
 955   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 956 #else
 957   c_register_pragma (0, "pack", handle_pragma_pack);
 958 #endif
 959 #endif
 960 #ifdef HANDLE_PRAGMA_PUSH_POP_MACRO
 961   c_register_pragma (0 ,"push_macro", handle_pragma_push_macro);
 962   c_register_pragma (0 ,"pop_macro", handle_pragma_pop_macro);
 963 #endif
 964 #ifdef HANDLE_PRAGMA_WEAK
 965   c_register_pragma (0, "weak", handle_pragma_weak);
 966 #endif
 967 #ifdef HANDLE_PRAGMA_VISIBILITY
 968   c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
 969 #endif
 970
 971   c_register_pragma ("GCC", "diagnostic", handle_pragma_diagnostic);
 972
 973   c_register_pragma_with_expansion (0, "redefine_extname", handle_pragma_redefine_extname);
 974   c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
 975
 976 #ifdef REGISTER_TARGET_PRAGMAS
 977   REGISTER_TARGET_PRAGMAS ();
 978 #endif
 979 }
 980
 981 #include "gt-c-pragma.h"