* final.c (output_asm_insn): Correct problem with -fverbose-asm.
[official-gcc.git] / gcc / c-pragma.c
blobfe9f17ab569f7e6448ec014c64fab7e40e7b6151
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
3 Free Software Foundation, Inc.
5 This file is part of GCC.
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.
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.
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, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
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 "target.h"
39 #define GCC_BAD(msgid) do { warning (msgid); return; } while (0)
40 #define GCC_BAD2(msgid, arg) do { warning (msgid, arg); return; } while (0)
42 typedef struct align_stack GTY(())
44 int alignment;
45 tree id;
46 struct align_stack * prev;
47 } align_stack;
49 static GTY(()) struct align_stack * alignment_stack;
51 #ifdef HANDLE_PRAGMA_PACK
52 static void handle_pragma_pack (cpp_reader *);
54 #ifdef HANDLE_PRAGMA_PACK_PUSH_POP
55 /* If we have a "global" #pragma pack(<n>) in effect when the first
56 #pragma pack(push,<n>) is encountered, this stores the value of
57 maximum_field_alignment in effect. When the final pop_alignment()
58 happens, we restore the value to this, not to a value of 0 for
59 maximum_field_alignment. Value is in bits. */
60 static int default_alignment;
61 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = *(alignment_stack == NULL \
62 ? &default_alignment \
63 : &alignment_stack->alignment) = (ALIGN))
65 static void push_alignment (int, tree);
66 static void pop_alignment (tree);
68 /* Push an alignment value onto the stack. */
69 static void
70 push_alignment (int alignment, tree id)
72 align_stack * entry;
74 entry = ggc_alloc (sizeof (* entry));
76 entry->alignment = alignment;
77 entry->id = id;
78 entry->prev = alignment_stack;
80 /* The current value of maximum_field_alignment is not necessarily
81 0 since there may be a #pragma pack(<n>) in effect; remember it
82 so that we can restore it after the final #pragma pop(). */
83 if (alignment_stack == NULL)
84 default_alignment = maximum_field_alignment;
86 alignment_stack = entry;
88 maximum_field_alignment = alignment;
91 /* Undo a push of an alignment onto the stack. */
92 static void
93 pop_alignment (tree id)
95 align_stack * entry;
97 if (alignment_stack == NULL)
98 GCC_BAD("#pragma pack (pop) encountered without matching #pragma pack (push)");
100 /* If we got an identifier, strip away everything above the target
101 entry so that the next step will restore the state just below it. */
102 if (id)
104 for (entry = alignment_stack; entry; entry = entry->prev)
105 if (entry->id == id)
107 alignment_stack = entry;
108 break;
110 if (entry == NULL)
111 warning ("\
112 #pragma pack(pop, %s) encountered without matching #pragma pack(push, %s)"
113 , IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
116 entry = alignment_stack->prev;
118 maximum_field_alignment = entry ? entry->alignment : default_alignment;
120 alignment_stack = entry;
122 #else /* not HANDLE_PRAGMA_PACK_PUSH_POP */
123 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = (ALIGN))
124 #define push_alignment(ID, N) \
125 GCC_BAD("#pragma pack(push[, id], <n>) is not supported on this target")
126 #define pop_alignment(ID) \
127 GCC_BAD("#pragma pack(pop[, id], <n>) is not supported on this target")
128 #endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
130 /* #pragma pack ()
131 #pragma pack (N)
133 #pragma pack (push)
134 #pragma pack (push, N)
135 #pragma pack (push, ID)
136 #pragma pack (push, ID, N)
137 #pragma pack (pop)
138 #pragma pack (pop, ID) */
139 static void
140 handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy))
142 tree x, id = 0;
143 int align = -1;
144 enum cpp_ttype token;
145 enum { set, push, pop } action;
147 if (c_lex (&x) != CPP_OPEN_PAREN)
148 GCC_BAD ("missing '(' after '#pragma pack' - ignored");
150 token = c_lex (&x);
151 if (token == CPP_CLOSE_PAREN)
153 action = set;
154 align = initial_max_fld_align;
156 else if (token == CPP_NUMBER)
158 align = TREE_INT_CST_LOW (x);
159 action = set;
160 if (c_lex (&x) != CPP_CLOSE_PAREN)
161 GCC_BAD ("malformed '#pragma pack' - ignored");
163 else if (token == CPP_NAME)
165 #define GCC_BAD_ACTION do { if (action != pop) \
166 GCC_BAD ("malformed '#pragma pack(push[, id][, <n>])' - ignored"); \
167 else \
168 GCC_BAD ("malformed '#pragma pack(pop[, id])' - ignored"); \
169 } while (0)
171 const char *op = IDENTIFIER_POINTER (x);
172 if (!strcmp (op, "push"))
173 action = push;
174 else if (!strcmp (op, "pop"))
175 action = pop;
176 else
177 GCC_BAD2 ("unknown action '%s' for '#pragma pack' - ignored", op);
179 while ((token = c_lex (&x)) == CPP_COMMA)
181 token = c_lex (&x);
182 if (token == CPP_NAME && id == 0)
184 id = x;
186 else if (token == CPP_NUMBER && action == push && align == -1)
188 align = TREE_INT_CST_LOW (x);
189 if (align == -1)
190 action = set;
192 else
193 GCC_BAD_ACTION;
196 if (token != CPP_CLOSE_PAREN)
197 GCC_BAD_ACTION;
198 #undef GCC_BAD_ACTION
200 else
201 GCC_BAD ("malformed '#pragma pack' - ignored");
203 if (c_lex (&x) != CPP_EOF)
204 warning ("junk at end of '#pragma pack'");
206 if (flag_pack_struct)
207 GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored");
209 if (action != pop)
210 switch (align)
212 case 0:
213 case 1:
214 case 2:
215 case 4:
216 case 8:
217 case 16:
218 align *= BITS_PER_UNIT;
219 break;
220 case -1:
221 if (action == push)
223 align = maximum_field_alignment;
224 break;
226 default:
227 GCC_BAD2 ("alignment must be a small power of two, not %d", align);
230 switch (action)
232 case set: SET_GLOBAL_ALIGNMENT (align); break;
233 case push: push_alignment (align, id); break;
234 case pop: pop_alignment (id); break;
237 #endif /* HANDLE_PRAGMA_PACK */
239 static GTY(()) tree pending_weaks;
241 #ifdef HANDLE_PRAGMA_WEAK
242 static void apply_pragma_weak (tree, tree);
243 static void handle_pragma_weak (cpp_reader *);
245 static void
246 apply_pragma_weak (tree decl, tree value)
248 if (value)
250 value = build_string (IDENTIFIER_LENGTH (value),
251 IDENTIFIER_POINTER (value));
252 decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
253 build_tree_list (NULL, value)),
257 if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
258 && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma. */
259 && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
260 warning ("%Japplying #pragma weak '%D' after first use results "
261 "in unspecified behavior", decl, decl);
263 declare_weak (decl);
266 void
267 maybe_apply_pragma_weak (tree decl)
269 tree *p, t, id;
271 /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed. */
273 /* No weak symbols pending, take the short-cut. */
274 if (!pending_weaks)
275 return;
276 /* If it's not visible outside this file, it doesn't matter whether
277 it's weak. */
278 if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
279 return;
280 /* If it's not a function or a variable, it can't be weak.
281 FIXME: what kinds of things are visible outside this file but
282 aren't functions or variables? Should this be an assert instead? */
283 if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
284 return;
286 id = DECL_ASSEMBLER_NAME (decl);
288 for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
289 if (id == TREE_PURPOSE (t))
291 apply_pragma_weak (decl, TREE_VALUE (t));
292 *p = TREE_CHAIN (t);
293 break;
297 /* #pragma weak name [= value] */
298 static void
299 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
301 tree name, value, x, decl;
302 enum cpp_ttype t;
304 value = 0;
306 if (c_lex (&name) != CPP_NAME)
307 GCC_BAD ("malformed #pragma weak, ignored");
308 t = c_lex (&x);
309 if (t == CPP_EQ)
311 if (c_lex (&value) != CPP_NAME)
312 GCC_BAD ("malformed #pragma weak, ignored");
313 t = c_lex (&x);
315 if (t != CPP_EOF)
316 warning ("junk at end of #pragma weak");
318 decl = identifier_global_value (name);
319 if (decl && TREE_CODE_CLASS (TREE_CODE (decl)) == 'd')
321 apply_pragma_weak (decl, value);
322 if (value)
323 assemble_alias (decl, value);
325 else
326 pending_weaks = tree_cons (name, value, pending_weaks);
328 #else
329 void
330 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
333 #endif /* HANDLE_PRAGMA_WEAK */
335 /* GCC supports two #pragma directives for renaming the external
336 symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
337 compatibility with the Solaris and Tru64 system headers. GCC also
338 has its own notation for this, __asm__("name") annotations.
340 Corner cases of these features and their interaction:
342 1) Both pragmas silently apply only to declarations with external
343 linkage (that is, TREE_PUBLIC || DECL_EXTERNAL). Asm labels
344 do not have this restriction.
346 2) In C++, both #pragmas silently apply only to extern "C" declarations.
347 Asm labels do not have this restriction.
349 3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
350 applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
351 new name is different, a warning issues and the name does not change.
353 4) The "source name" for #pragma redefine_extname is the DECL_NAME,
354 *not* the DECL_ASSEMBLER_NAME.
356 5) If #pragma extern_prefix is in effect and a declaration occurs
357 with an __asm__ name, the #pragma extern_prefix is silently
358 ignored for that declaration.
360 6) If #pragma extern_prefix and #pragma redefine_extname apply to
361 the same declaration, whichever triggered first wins, and a warning
362 is issued. (We would like to have #pragma redefine_extname always
363 win, but it can appear either before or after the declaration, and
364 if it appears afterward, we have no way of knowing whether a modified
365 DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.) */
367 static GTY(()) tree pending_redefine_extname;
369 static void handle_pragma_redefine_extname (cpp_reader *);
371 /* #pragma redefine_extname oldname newname */
372 static void
373 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
375 tree oldname, newname, decl, x;
376 enum cpp_ttype t;
378 if (c_lex (&oldname) != CPP_NAME)
379 GCC_BAD ("malformed #pragma redefine_extname, ignored");
380 if (c_lex (&newname) != CPP_NAME)
381 GCC_BAD ("malformed #pragma redefine_extname, ignored");
382 t = c_lex (&x);
383 if (t != CPP_EOF)
384 warning ("junk at end of #pragma redefine_extname");
386 if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
388 if (warn_unknown_pragmas > in_system_header)
389 warning ("#pragma redefine_extname not supported on this target");
390 return;
393 decl = identifier_global_value (oldname);
394 if (decl
395 && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
396 && (TREE_CODE (decl) == FUNCTION_DECL
397 || TREE_CODE (decl) == VAR_DECL)
398 && has_c_linkage (decl))
400 if (DECL_ASSEMBLER_NAME_SET_P (decl))
402 const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
403 name = targetm.strip_name_encoding (name);
405 if (strcmp (name, IDENTIFIER_POINTER (newname)))
406 warning ("#pragma redefine_extname ignored due to conflict with "
407 "previous rename");
409 else
410 change_decl_assembler_name (decl, newname);
412 else
413 /* We have to add this to the rename list even if there's already
414 a global value that doesn't meet the above criteria, because in
415 C++ "struct foo {...};" puts "foo" in the current namespace but
416 does *not* conflict with a subsequent declaration of a function
417 or variable foo. See g++.dg/other/pragma-re-2.C. */
418 add_to_renaming_pragma_list (oldname, newname);
421 /* This is called from here and from ia64.c. */
422 void
423 add_to_renaming_pragma_list (tree oldname, tree newname)
425 tree previous = purpose_member (oldname, pending_redefine_extname);
426 if (previous)
428 if (TREE_VALUE (previous) != newname)
429 warning ("#pragma redefine_extname ignored due to conflict with "
430 "previous #pragma redefine_extname");
431 return;
434 pending_redefine_extname
435 = tree_cons (oldname, newname, pending_redefine_extname);
438 static GTY(()) tree pragma_extern_prefix;
440 /* #pragma extern_prefix "prefix" */
441 static void
442 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
444 tree prefix, x;
445 enum cpp_ttype t;
447 if (c_lex (&prefix) != CPP_STRING)
448 GCC_BAD ("malformed #pragma extern_prefix, ignored");
449 t = c_lex (&x);
450 if (t != CPP_EOF)
451 warning ("junk at end of #pragma extern_prefix");
453 if (targetm.handle_pragma_extern_prefix)
454 /* Note that the length includes the null terminator. */
455 pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
456 else if (warn_unknown_pragmas > in_system_header)
457 warning ("#pragma extern_prefix not supported on this target");
460 /* Hook from the front ends to apply the results of one of the preceding
461 pragmas that rename variables. */
463 tree
464 maybe_apply_renaming_pragma (tree decl, tree asmname)
466 tree *p, t;
468 /* The renaming pragmas are only applied to declarations with
469 external linkage. */
470 if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
471 || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
472 || !has_c_linkage (decl))
473 return asmname;
475 /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
476 but we may warn about a rename that conflicts. */
477 if (DECL_ASSEMBLER_NAME_SET_P (decl))
479 const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
480 oldname = targetm.strip_name_encoding (oldname);
482 if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
483 warning ("asm declaration ignored due to "
484 "conflict with previous rename");
486 /* Take any pending redefine_extname off the list. */
487 for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
488 if (DECL_NAME (decl) == TREE_PURPOSE (t))
490 /* Only warn if there is a conflict. */
491 if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
492 warning ("#pragma redefine_extname ignored due to "
493 "conflict with previous rename");
495 *p = TREE_CHAIN (t);
496 break;
498 return 0;
501 /* Find out if we have a pending #pragma redefine_extname. */
502 for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
503 if (DECL_NAME (decl) == TREE_PURPOSE (t))
505 tree newname = TREE_VALUE (t);
506 *p = TREE_CHAIN (t);
508 /* If we already have an asmname, #pragma redefine_extname is
509 ignored (with a warning if it conflicts). */
510 if (asmname)
512 if (strcmp (TREE_STRING_POINTER (asmname),
513 IDENTIFIER_POINTER (newname)) != 0)
514 warning ("#pragma redefine_extname ignored due to "
515 "conflict with __asm__ declaration");
516 return asmname;
519 /* Otherwise we use what we've got; #pragma extern_prefix is
520 silently ignored. */
521 return build_string (IDENTIFIER_LENGTH (newname),
522 IDENTIFIER_POINTER (newname));
525 /* If we've got an asmname, #pragma extern_prefix is silently ignored. */
526 if (asmname)
527 return asmname;
529 /* If #pragma extern_prefix is in effect, apply it. */
530 if (pragma_extern_prefix)
532 const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
533 size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
535 const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
536 size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
538 char *newname = (char *) alloca (plen + ilen + 1);
540 memcpy (newname, prefix, plen);
541 memcpy (newname + plen, id, ilen + 1);
543 return build_string (plen + ilen, newname);
546 /* Nada. */
547 return 0;
551 #ifdef HANDLE_PRAGMA_VISIBILITY
552 static void handle_pragma_visibility (cpp_reader *);
554 /* Sets the default visibility for symbols to something other than that
555 specified on the command line. */
556 static void
557 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
558 { /* Form is #pragma GCC visibility push(hidden)|pop */
559 static int visstack [16], visidx;
560 tree x;
561 enum cpp_ttype token;
562 enum { bad, push, pop } action = bad;
564 token = c_lex (&x);
565 if (token == CPP_NAME)
567 const char *op = IDENTIFIER_POINTER (x);
568 if (!strcmp (op, "push"))
569 action = push;
570 else if (!strcmp (op, "pop"))
571 action = pop;
573 if (bad == action)
574 GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
575 else
577 if (pop == action)
579 if (!visidx)
581 GCC_BAD ("No matching push for '#pragma GCC visibility pop'");
583 else
585 default_visibility = visstack[--visidx];
586 visibility_options.inpragma = (visidx>0);
589 else
591 if (c_lex (&x) != CPP_OPEN_PAREN)
592 GCC_BAD ("missing '(' after '#pragma GCC visibility push' - ignored");
593 token = c_lex (&x);
594 if (token != CPP_NAME)
596 GCC_BAD ("malformed #pragma GCC visibility push");
598 else if (visidx >= 16)
600 GCC_BAD ("No more than sixteen #pragma GCC visibility pushes allowed at once");
602 else
604 const char *str = IDENTIFIER_POINTER (x);
605 visstack[visidx++] = default_visibility;
606 if (!strcmp (str, "default"))
607 default_visibility = VISIBILITY_DEFAULT;
608 else if (!strcmp (str, "internal"))
609 default_visibility = VISIBILITY_INTERNAL;
610 else if (!strcmp (str, "hidden"))
611 default_visibility = VISIBILITY_HIDDEN;
612 else if (!strcmp (str, "protected"))
613 default_visibility = VISIBILITY_PROTECTED;
614 else
616 GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
618 visibility_options.inpragma = 1;
620 if (c_lex (&x) != CPP_CLOSE_PAREN)
621 GCC_BAD ("missing '(' after '#pragma GCC visibility push' - ignored");
624 if (c_lex (&x) != CPP_EOF)
625 warning ("junk at end of '#pragma GCC visibility'");
628 #endif
630 /* Front-end wrapper for pragma registration to avoid dragging
631 cpplib.h in almost everywhere. */
632 void
633 c_register_pragma (const char *space, const char *name,
634 void (*handler) (struct cpp_reader *))
636 cpp_register_pragma (parse_in, space, name, handler);
639 /* Set up front-end pragmas. */
640 void
641 init_pragma (void)
643 #ifdef HANDLE_PRAGMA_PACK
644 c_register_pragma (0, "pack", handle_pragma_pack);
645 #endif
646 #ifdef HANDLE_PRAGMA_WEAK
647 c_register_pragma (0, "weak", handle_pragma_weak);
648 #endif
649 #ifdef HANDLE_PRAGMA_VISIBILITY
650 c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
651 #endif
653 c_register_pragma (0, "redefine_extname", handle_pragma_redefine_extname);
654 c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
656 c_register_pragma ("GCC", "pch_preprocess", c_common_pch_pragma);
658 #ifdef REGISTER_TARGET_PRAGMAS
659 REGISTER_TARGET_PRAGMAS ();
660 #endif
663 #include "gt-c-pragma.h"