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
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
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
24 #include "coretypes.h"
39 #define GCC_BAD(gmsgid) do { warning (gmsgid); return; } while (0)
40 #define GCC_BAD2(gmsgid, arg) \
41 do { warning (gmsgid, arg); return; } while (0)
43 typedef struct align_stack GTY(())
47 struct align_stack * prev;
50 static GTY(()) struct align_stack * alignment_stack;
52 #ifdef HANDLE_PRAGMA_PACK
53 static void handle_pragma_pack (cpp_reader *);
55 #ifdef HANDLE_PRAGMA_PACK_PUSH_POP
56 /* If we have a "global" #pragma pack(<n>) in effect when the first
57 #pragma pack(push,<n>) is encountered, this stores the value of
58 maximum_field_alignment in effect. When the final pop_alignment()
59 happens, we restore the value to this, not to a value of 0 for
60 maximum_field_alignment. Value is in bits. */
61 static int default_alignment;
62 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = *(alignment_stack == NULL \
63 ? &default_alignment \
64 : &alignment_stack->alignment) = (ALIGN))
66 static void push_alignment (int, tree);
67 static void pop_alignment (tree);
69 /* Push an alignment value onto the stack. */
71 push_alignment (int alignment, tree id)
75 entry = ggc_alloc (sizeof (* entry));
77 entry->alignment = alignment;
79 entry->prev = alignment_stack;
81 /* The current value of maximum_field_alignment is not necessarily
82 0 since there may be a #pragma pack(<n>) in effect; remember it
83 so that we can restore it after the final #pragma pop(). */
84 if (alignment_stack == NULL)
85 default_alignment = maximum_field_alignment;
87 alignment_stack = entry;
89 maximum_field_alignment = alignment;
92 /* Undo a push of an alignment onto the stack. */
94 pop_alignment (tree id)
98 if (alignment_stack == NULL)
99 GCC_BAD ("#pragma pack (pop) encountered without matching #pragma pack (push)");
101 /* If we got an identifier, strip away everything above the target
102 entry so that the next step will restore the state just below it. */
105 for (entry = alignment_stack; entry; entry = entry->prev)
108 alignment_stack = entry;
113 #pragma pack(pop, %s) encountered without matching #pragma pack(push, %s)"
114 , IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
117 entry = alignment_stack->prev;
119 maximum_field_alignment = entry ? entry->alignment : default_alignment;
121 alignment_stack = entry;
123 #else /* not HANDLE_PRAGMA_PACK_PUSH_POP */
124 #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = (ALIGN))
125 #define push_alignment(ID, N) \
126 GCC_BAD ("#pragma pack(push[, id], <n>) is not supported on this target")
127 #define pop_alignment(ID) \
128 GCC_BAD ("#pragma pack(pop[, id], <n>) is not supported on this target")
129 #endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
135 #pragma pack (push, N)
136 #pragma pack (push, ID)
137 #pragma pack (push, ID, N)
139 #pragma pack (pop, ID) */
141 handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy))
145 enum cpp_ttype token;
146 enum { set, push, pop } action;
148 if (c_lex (&x) != CPP_OPEN_PAREN)
149 GCC_BAD ("missing %<(%> after %<#pragma pack%> - ignored");
152 if (token == CPP_CLOSE_PAREN)
155 align = initial_max_fld_align;
157 else if (token == CPP_NUMBER)
159 align = TREE_INT_CST_LOW (x);
161 if (c_lex (&x) != CPP_CLOSE_PAREN)
162 GCC_BAD ("malformed %<#pragma pack%> - ignored");
164 else if (token == CPP_NAME)
166 #define GCC_BAD_ACTION do { if (action != pop) \
167 GCC_BAD ("malformed %<#pragma pack(push[, id][, <n>])%> - ignored"); \
169 GCC_BAD ("malformed %<#pragma pack(pop[, id])%> - ignored"); \
172 const char *op = IDENTIFIER_POINTER (x);
173 if (!strcmp (op, "push"))
175 else if (!strcmp (op, "pop"))
178 GCC_BAD2 ("unknown action %qs for %<#pragma pack%> - ignored", op);
180 while ((token = c_lex (&x)) == CPP_COMMA)
183 if (token == CPP_NAME && id == 0)
187 else if (token == CPP_NUMBER && action == push && align == -1)
189 align = TREE_INT_CST_LOW (x);
197 if (token != CPP_CLOSE_PAREN)
199 #undef GCC_BAD_ACTION
202 GCC_BAD ("malformed %<#pragma pack%> - ignored");
204 if (c_lex (&x) != CPP_EOF)
205 warning ("junk at end of %<#pragma pack%>");
207 if (flag_pack_struct)
208 GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored");
219 align *= BITS_PER_UNIT;
224 align = maximum_field_alignment;
228 GCC_BAD2 ("alignment must be a small power of two, not %d", align);
233 case set: SET_GLOBAL_ALIGNMENT (align); break;
234 case push: push_alignment (align, id); break;
235 case pop: pop_alignment (id); break;
238 #endif /* HANDLE_PRAGMA_PACK */
240 static GTY(()) tree pending_weaks;
242 #ifdef HANDLE_PRAGMA_WEAK
243 static void apply_pragma_weak (tree, tree);
244 static void handle_pragma_weak (cpp_reader *);
247 apply_pragma_weak (tree decl, tree value)
251 value = build_string (IDENTIFIER_LENGTH (value),
252 IDENTIFIER_POINTER (value));
253 decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
254 build_tree_list (NULL, value)),
258 if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl)
259 && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma. */
260 && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
261 warning ("%Japplying #pragma weak %qD after first use results "
262 "in unspecified behavior", decl, decl);
268 maybe_apply_pragma_weak (tree decl)
272 /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed. */
274 /* No weak symbols pending, take the short-cut. */
277 /* If it's not visible outside this file, it doesn't matter whether
279 if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl))
281 /* If it's not a function or a variable, it can't be weak.
282 FIXME: what kinds of things are visible outside this file but
283 aren't functions or variables? Should this be an assert instead? */
284 if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
287 id = DECL_ASSEMBLER_NAME (decl);
289 for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t))
290 if (id == TREE_PURPOSE (t))
292 apply_pragma_weak (decl, TREE_VALUE (t));
298 /* Process all "#pragma weak A = B" directives where we have not seen
301 maybe_apply_pending_pragma_weaks (void)
303 tree *p, t, alias_id, id, decl, *next;
305 for (p = &pending_weaks; (t = *p) ; p = next)
307 next = &TREE_CHAIN (t);
308 alias_id = TREE_PURPOSE (t);
311 if (TREE_VALUE (t) == NULL)
314 decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
316 DECL_ARTIFICIAL (decl) = 1;
317 TREE_PUBLIC (decl) = 1;
318 DECL_EXTERNAL (decl) = 1;
319 DECL_WEAK (decl) = 1;
321 assemble_alias (decl, id);
325 /* #pragma weak name [= value] */
327 handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy))
329 tree name, value, x, decl;
334 if (c_lex (&name) != CPP_NAME)
335 GCC_BAD ("malformed #pragma weak, ignored");
339 if (c_lex (&value) != CPP_NAME)
340 GCC_BAD ("malformed #pragma weak, ignored");
344 warning ("junk at end of #pragma weak");
346 decl = identifier_global_value (name);
347 if (decl && DECL_P (decl))
349 apply_pragma_weak (decl, value);
351 assemble_alias (decl, value);
354 pending_weaks = tree_cons (name, value, pending_weaks);
358 maybe_apply_pragma_weak (tree ARG_UNUSED (decl))
363 maybe_apply_pending_pragma_weaks (void)
366 #endif /* HANDLE_PRAGMA_WEAK */
368 /* GCC supports two #pragma directives for renaming the external
369 symbol associated with a declaration (DECL_ASSEMBLER_NAME), for
370 compatibility with the Solaris and Tru64 system headers. GCC also
371 has its own notation for this, __asm__("name") annotations.
373 Corner cases of these features and their interaction:
375 1) Both pragmas silently apply only to declarations with external
376 linkage (that is, TREE_PUBLIC || DECL_EXTERNAL). Asm labels
377 do not have this restriction.
379 2) In C++, both #pragmas silently apply only to extern "C" declarations.
380 Asm labels do not have this restriction.
382 3) If any of the three ways of changing DECL_ASSEMBLER_NAME is
383 applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the
384 new name is different, a warning issues and the name does not change.
386 4) The "source name" for #pragma redefine_extname is the DECL_NAME,
387 *not* the DECL_ASSEMBLER_NAME.
389 5) If #pragma extern_prefix is in effect and a declaration occurs
390 with an __asm__ name, the #pragma extern_prefix is silently
391 ignored for that declaration.
393 6) If #pragma extern_prefix and #pragma redefine_extname apply to
394 the same declaration, whichever triggered first wins, and a warning
395 is issued. (We would like to have #pragma redefine_extname always
396 win, but it can appear either before or after the declaration, and
397 if it appears afterward, we have no way of knowing whether a modified
398 DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.) */
400 static GTY(()) tree pending_redefine_extname;
402 static void handle_pragma_redefine_extname (cpp_reader *);
404 /* #pragma redefine_extname oldname newname */
406 handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy))
408 tree oldname, newname, decl, x;
411 if (c_lex (&oldname) != CPP_NAME)
412 GCC_BAD ("malformed #pragma redefine_extname, ignored");
413 if (c_lex (&newname) != CPP_NAME)
414 GCC_BAD ("malformed #pragma redefine_extname, ignored");
417 warning ("junk at end of #pragma redefine_extname");
419 if (!flag_mudflap && !targetm.handle_pragma_redefine_extname)
421 if (warn_unknown_pragmas > in_system_header)
422 warning ("#pragma redefine_extname not supported on this target");
426 decl = identifier_global_value (oldname);
428 && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
429 && (TREE_CODE (decl) == FUNCTION_DECL
430 || TREE_CODE (decl) == VAR_DECL)
431 && has_c_linkage (decl))
433 if (DECL_ASSEMBLER_NAME_SET_P (decl))
435 const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
436 name = targetm.strip_name_encoding (name);
438 if (strcmp (name, IDENTIFIER_POINTER (newname)))
439 warning ("#pragma redefine_extname ignored due to conflict with "
443 change_decl_assembler_name (decl, newname);
446 /* We have to add this to the rename list even if there's already
447 a global value that doesn't meet the above criteria, because in
448 C++ "struct foo {...};" puts "foo" in the current namespace but
449 does *not* conflict with a subsequent declaration of a function
450 or variable foo. See g++.dg/other/pragma-re-2.C. */
451 add_to_renaming_pragma_list (oldname, newname);
454 /* This is called from here and from ia64.c. */
456 add_to_renaming_pragma_list (tree oldname, tree newname)
458 tree previous = purpose_member (oldname, pending_redefine_extname);
461 if (TREE_VALUE (previous) != newname)
462 warning ("#pragma redefine_extname ignored due to conflict with "
463 "previous #pragma redefine_extname");
467 pending_redefine_extname
468 = tree_cons (oldname, newname, pending_redefine_extname);
471 static GTY(()) tree pragma_extern_prefix;
473 /* #pragma extern_prefix "prefix" */
475 handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
480 if (c_lex (&prefix) != CPP_STRING)
481 GCC_BAD ("malformed #pragma extern_prefix, ignored");
484 warning ("junk at end of #pragma extern_prefix");
486 if (targetm.handle_pragma_extern_prefix)
487 /* Note that the length includes the null terminator. */
488 pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL);
489 else if (warn_unknown_pragmas > in_system_header)
490 warning ("#pragma extern_prefix not supported on this target");
493 /* Hook from the front ends to apply the results of one of the preceding
494 pragmas that rename variables. */
497 maybe_apply_renaming_pragma (tree decl, tree asmname)
501 /* The renaming pragmas are only applied to declarations with
503 if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL)
504 || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl))
505 || !has_c_linkage (decl))
508 /* If the DECL_ASSEMBLER_NAME is already set, it does not change,
509 but we may warn about a rename that conflicts. */
510 if (DECL_ASSEMBLER_NAME_SET_P (decl))
512 const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
513 oldname = targetm.strip_name_encoding (oldname);
515 if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname))
516 warning ("asm declaration ignored due to "
517 "conflict with previous rename");
519 /* Take any pending redefine_extname off the list. */
520 for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
521 if (DECL_NAME (decl) == TREE_PURPOSE (t))
523 /* Only warn if there is a conflict. */
524 if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname))
525 warning ("#pragma redefine_extname ignored due to "
526 "conflict with previous rename");
534 /* Find out if we have a pending #pragma redefine_extname. */
535 for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t))
536 if (DECL_NAME (decl) == TREE_PURPOSE (t))
538 tree newname = TREE_VALUE (t);
541 /* If we already have an asmname, #pragma redefine_extname is
542 ignored (with a warning if it conflicts). */
545 if (strcmp (TREE_STRING_POINTER (asmname),
546 IDENTIFIER_POINTER (newname)) != 0)
547 warning ("#pragma redefine_extname ignored due to "
548 "conflict with __asm__ declaration");
552 /* Otherwise we use what we've got; #pragma extern_prefix is
554 return build_string (IDENTIFIER_LENGTH (newname),
555 IDENTIFIER_POINTER (newname));
558 /* If we've got an asmname, #pragma extern_prefix is silently ignored. */
562 /* If #pragma extern_prefix is in effect, apply it. */
563 if (pragma_extern_prefix)
565 const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix);
566 size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1;
568 const char *id = IDENTIFIER_POINTER (DECL_NAME (decl));
569 size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl));
571 char *newname = (char *) alloca (plen + ilen + 1);
573 memcpy (newname, prefix, plen);
574 memcpy (newname + plen, id, ilen + 1);
576 return build_string (plen + ilen, newname);
584 #ifdef HANDLE_PRAGMA_VISIBILITY
585 static void handle_pragma_visibility (cpp_reader *);
587 /* Sets the default visibility for symbols to something other than that
588 specified on the command line. */
590 handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED)
591 { /* Form is #pragma GCC visibility push(hidden)|pop */
592 static int visstack [16], visidx;
594 enum cpp_ttype token;
595 enum { bad, push, pop } action = bad;
598 if (token == CPP_NAME)
600 const char *op = IDENTIFIER_POINTER (x);
601 if (!strcmp (op, "push"))
603 else if (!strcmp (op, "pop"))
607 GCC_BAD ("#pragma GCC visibility must be followed by push or pop");
614 GCC_BAD ("No matching push for %<#pragma GCC visibility pop%>");
618 default_visibility = visstack[--visidx];
619 visibility_options.inpragma = (visidx>0);
624 if (c_lex (&x) != CPP_OPEN_PAREN)
625 GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
627 if (token != CPP_NAME)
629 GCC_BAD ("malformed #pragma GCC visibility push");
631 else if (visidx >= 16)
633 GCC_BAD ("No more than sixteen #pragma GCC visibility pushes allowed at once");
637 const char *str = IDENTIFIER_POINTER (x);
638 visstack[visidx++] = default_visibility;
639 if (!strcmp (str, "default"))
640 default_visibility = VISIBILITY_DEFAULT;
641 else if (!strcmp (str, "internal"))
642 default_visibility = VISIBILITY_INTERNAL;
643 else if (!strcmp (str, "hidden"))
644 default_visibility = VISIBILITY_HIDDEN;
645 else if (!strcmp (str, "protected"))
646 default_visibility = VISIBILITY_PROTECTED;
649 GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected");
651 visibility_options.inpragma = 1;
653 if (c_lex (&x) != CPP_CLOSE_PAREN)
654 GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");
657 if (c_lex (&x) != CPP_EOF)
658 warning ("junk at end of %<#pragma GCC visibility%>");
663 /* Front-end wrappers for pragma registration to avoid dragging
664 cpplib.h in almost everywhere. */
666 c_register_pragma (const char *space, const char *name,
667 void (*handler) (struct cpp_reader *))
669 cpp_register_pragma (parse_in, space, name, handler, 0);
673 c_register_pragma_with_expansion (const char *space, const char *name,
674 void (*handler) (struct cpp_reader *))
676 cpp_register_pragma (parse_in, space, name, handler, 1);
679 /* Set up front-end pragmas. */
683 #ifdef HANDLE_PRAGMA_PACK
684 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
685 c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
687 c_register_pragma (0, "pack", handle_pragma_pack);
690 #ifdef HANDLE_PRAGMA_WEAK
691 c_register_pragma (0, "weak", handle_pragma_weak);
693 #ifdef HANDLE_PRAGMA_VISIBILITY
694 c_register_pragma ("GCC", "visibility", handle_pragma_visibility);
697 c_register_pragma (0, "redefine_extname", handle_pragma_redefine_extname);
698 c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
700 c_register_pragma ("GCC", "pch_preprocess", c_common_pch_pragma);
702 #ifdef REGISTER_TARGET_PRAGMAS
703 REGISTER_TARGET_PRAGMAS ();
707 #include "gt-c-pragma.h"