/* Handle #pragma, system V.4 style. Supports #pragma weak and #pragma pack. Copyright (C) 1992, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "rtl.h" #include "tree.h" #include "function.h" #include "cpplib.h" #include "c-pragma.h" #include "flags.h" #include "toplev.h" #include "ggc.h" #include "c-common.h" #include "output.h" #include "tm_p.h" #include "vec.h" #include "target.h" #define GCC_BAD(gmsgid) do { warning (0, gmsgid); return; } while (0) #define GCC_BAD2(gmsgid, arg) \ do { warning (0, gmsgid, arg); return; } while (0) typedef struct align_stack GTY(()) { int alignment; tree id; struct align_stack * prev; } align_stack; static GTY(()) struct align_stack * alignment_stack; #ifdef HANDLE_PRAGMA_PACK static void handle_pragma_pack (cpp_reader *); #ifdef HANDLE_PRAGMA_PACK_PUSH_POP /* If we have a "global" #pragma pack() in effect when the first #pragma pack(push,) is encountered, this stores the value of maximum_field_alignment in effect. When the final pop_alignment() happens, we restore the value to this, not to a value of 0 for maximum_field_alignment. Value is in bits. */ static int default_alignment; #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = *(alignment_stack == NULL \ ? &default_alignment \ : &alignment_stack->alignment) = (ALIGN)) static void push_alignment (int, tree); static void pop_alignment (tree); /* Push an alignment value onto the stack. */ static void push_alignment (int alignment, tree id) { align_stack * entry; entry = ggc_alloc (sizeof (* entry)); entry->alignment = alignment; entry->id = id; entry->prev = alignment_stack; /* The current value of maximum_field_alignment is not necessarily 0 since there may be a #pragma pack() in effect; remember it so that we can restore it after the final #pragma pop(). */ if (alignment_stack == NULL) default_alignment = maximum_field_alignment; alignment_stack = entry; maximum_field_alignment = alignment; } /* Undo a push of an alignment onto the stack. */ static void pop_alignment (tree id) { align_stack * entry; if (alignment_stack == NULL) GCC_BAD ("#pragma pack (pop) encountered without matching #pragma pack (push)"); /* If we got an identifier, strip away everything above the target entry so that the next step will restore the state just below it. */ if (id) { for (entry = alignment_stack; entry; entry = entry->prev) if (entry->id == id) { alignment_stack = entry; break; } if (entry == NULL) warning (0, "\ #pragma pack(pop, %s) encountered without matching #pragma pack(push, %s)" , IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id)); } entry = alignment_stack->prev; maximum_field_alignment = entry ? entry->alignment : default_alignment; alignment_stack = entry; } #else /* not HANDLE_PRAGMA_PACK_PUSH_POP */ #define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment = (ALIGN)) #define push_alignment(ID, N) \ GCC_BAD ("#pragma pack(push[, id], ) is not supported on this target") #define pop_alignment(ID) \ GCC_BAD ("#pragma pack(pop[, id], ) is not supported on this target") #endif /* HANDLE_PRAGMA_PACK_PUSH_POP */ /* #pragma pack () #pragma pack (N) #pragma pack (push) #pragma pack (push, N) #pragma pack (push, ID) #pragma pack (push, ID, N) #pragma pack (pop) #pragma pack (pop, ID) */ static void handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy)) { tree x, id = 0; int align = -1; enum cpp_ttype token; enum { set, push, pop } action; if (c_lex (&x) != CPP_OPEN_PAREN) GCC_BAD ("missing %<(%> after %<#pragma pack%> - ignored"); token = c_lex (&x); if (token == CPP_CLOSE_PAREN) { action = set; align = initial_max_fld_align; } else if (token == CPP_NUMBER) { align = TREE_INT_CST_LOW (x); action = set; if (c_lex (&x) != CPP_CLOSE_PAREN) GCC_BAD ("malformed %<#pragma pack%> - ignored"); } else if (token == CPP_NAME) { #define GCC_BAD_ACTION do { if (action != pop) \ GCC_BAD ("malformed %<#pragma pack(push[, id][, ])%> - ignored"); \ else \ GCC_BAD ("malformed %<#pragma pack(pop[, id])%> - ignored"); \ } while (0) const char *op = IDENTIFIER_POINTER (x); if (!strcmp (op, "push")) action = push; else if (!strcmp (op, "pop")) action = pop; else GCC_BAD2 ("unknown action %qs for %<#pragma pack%> - ignored", op); while ((token = c_lex (&x)) == CPP_COMMA) { token = c_lex (&x); if (token == CPP_NAME && id == 0) { id = x; } else if (token == CPP_NUMBER && action == push && align == -1) { align = TREE_INT_CST_LOW (x); if (align == -1) action = set; } else GCC_BAD_ACTION; } if (token != CPP_CLOSE_PAREN) GCC_BAD_ACTION; #undef GCC_BAD_ACTION } else GCC_BAD ("malformed %<#pragma pack%> - ignored"); if (c_lex (&x) != CPP_EOF) warning (0, "junk at end of %<#pragma pack%>"); if (flag_pack_struct) GCC_BAD ("#pragma pack has no effect with -fpack-struct - ignored"); if (action != pop) switch (align) { case 0: case 1: case 2: case 4: case 8: case 16: align *= BITS_PER_UNIT; break; case -1: if (action == push) { align = maximum_field_alignment; break; } default: GCC_BAD2 ("alignment must be a small power of two, not %d", align); } switch (action) { case set: SET_GLOBAL_ALIGNMENT (align); break; case push: push_alignment (align, id); break; case pop: pop_alignment (id); break; } } #endif /* HANDLE_PRAGMA_PACK */ static GTY(()) tree pending_weaks; #ifdef HANDLE_PRAGMA_WEAK static void apply_pragma_weak (tree, tree); static void handle_pragma_weak (cpp_reader *); static void apply_pragma_weak (tree decl, tree value) { if (value) { value = build_string (IDENTIFIER_LENGTH (value), IDENTIFIER_POINTER (value)); decl_attributes (&decl, build_tree_list (get_identifier ("alias"), build_tree_list (NULL, value)), 0); } if (SUPPORTS_WEAK && DECL_EXTERNAL (decl) && TREE_USED (decl) && !DECL_WEAK (decl) /* Don't complain about a redundant #pragma. */ && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))) warning (0, "applying #pragma weak %q+D after first use results " "in unspecified behavior", decl); declare_weak (decl); } void maybe_apply_pragma_weak (tree decl) { tree *p, t, id; /* Avoid asking for DECL_ASSEMBLER_NAME when it's not needed. */ /* No weak symbols pending, take the short-cut. */ if (!pending_weaks) return; /* If it's not visible outside this file, it doesn't matter whether it's weak. */ if (!DECL_EXTERNAL (decl) && !TREE_PUBLIC (decl)) return; /* If it's not a function or a variable, it can't be weak. FIXME: what kinds of things are visible outside this file but aren't functions or variables? Should this be an assert instead? */ if (TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL) return; id = DECL_ASSEMBLER_NAME (decl); for (p = &pending_weaks; (t = *p) ; p = &TREE_CHAIN (t)) if (id == TREE_PURPOSE (t)) { apply_pragma_weak (decl, TREE_VALUE (t)); *p = TREE_CHAIN (t); break; } } /* Process all "#pragma weak A = B" directives where we have not seen a decl for A. */ void maybe_apply_pending_pragma_weaks (void) { tree *p, t, alias_id, id, decl, *next; for (p = &pending_weaks; (t = *p) ; p = next) { next = &TREE_CHAIN (t); alias_id = TREE_PURPOSE (t); id = TREE_VALUE (t); if (TREE_VALUE (t) == NULL) continue; decl = build_decl (FUNCTION_DECL, alias_id, default_function_type); DECL_ARTIFICIAL (decl) = 1; TREE_PUBLIC (decl) = 1; DECL_EXTERNAL (decl) = 1; DECL_WEAK (decl) = 1; assemble_alias (decl, id); } } /* #pragma weak name [= value] */ static void handle_pragma_weak (cpp_reader * ARG_UNUSED (dummy)) { tree name, value, x, decl; enum cpp_ttype t; value = 0; if (c_lex (&name) != CPP_NAME) GCC_BAD ("malformed #pragma weak, ignored"); t = c_lex (&x); if (t == CPP_EQ) { if (c_lex (&value) != CPP_NAME) GCC_BAD ("malformed #pragma weak, ignored"); t = c_lex (&x); } if (t != CPP_EOF) warning (0, "junk at end of #pragma weak"); decl = identifier_global_value (name); if (decl && DECL_P (decl)) { apply_pragma_weak (decl, value); if (value) assemble_alias (decl, value); } else pending_weaks = tree_cons (name, value, pending_weaks); } #else void maybe_apply_pragma_weak (tree ARG_UNUSED (decl)) { } void maybe_apply_pending_pragma_weaks (void) { } #endif /* HANDLE_PRAGMA_WEAK */ /* GCC supports two #pragma directives for renaming the external symbol associated with a declaration (DECL_ASSEMBLER_NAME), for compatibility with the Solaris and Tru64 system headers. GCC also has its own notation for this, __asm__("name") annotations. Corner cases of these features and their interaction: 1) Both pragmas silently apply only to declarations with external linkage (that is, TREE_PUBLIC || DECL_EXTERNAL). Asm labels do not have this restriction. 2) In C++, both #pragmas silently apply only to extern "C" declarations. Asm labels do not have this restriction. 3) If any of the three ways of changing DECL_ASSEMBLER_NAME is applied to a decl whose DECL_ASSEMBLER_NAME is already set, and the new name is different, a warning issues and the name does not change. 4) The "source name" for #pragma redefine_extname is the DECL_NAME, *not* the DECL_ASSEMBLER_NAME. 5) If #pragma extern_prefix is in effect and a declaration occurs with an __asm__ name, the #pragma extern_prefix is silently ignored for that declaration. 6) If #pragma extern_prefix and #pragma redefine_extname apply to the same declaration, whichever triggered first wins, and a warning is issued. (We would like to have #pragma redefine_extname always win, but it can appear either before or after the declaration, and if it appears afterward, we have no way of knowing whether a modified DECL_ASSEMBLER_NAME is due to #pragma extern_prefix.) */ static GTY(()) tree pending_redefine_extname; static void handle_pragma_redefine_extname (cpp_reader *); /* #pragma redefine_extname oldname newname */ static void handle_pragma_redefine_extname (cpp_reader * ARG_UNUSED (dummy)) { tree oldname, newname, decl, x; enum cpp_ttype t; if (c_lex (&oldname) != CPP_NAME) GCC_BAD ("malformed #pragma redefine_extname, ignored"); if (c_lex (&newname) != CPP_NAME) GCC_BAD ("malformed #pragma redefine_extname, ignored"); t = c_lex (&x); if (t != CPP_EOF) warning (0, "junk at end of #pragma redefine_extname"); if (!flag_mudflap && !targetm.handle_pragma_redefine_extname) { if (warn_unknown_pragmas > in_system_header) warning (OPT_Wunknown_pragmas, "#pragma redefine_extname not supported on this target"); return; } decl = identifier_global_value (oldname); if (decl && (TREE_PUBLIC (decl) || DECL_EXTERNAL (decl)) && (TREE_CODE (decl) == FUNCTION_DECL || TREE_CODE (decl) == VAR_DECL) && has_c_linkage (decl)) { if (DECL_ASSEMBLER_NAME_SET_P (decl)) { const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)); name = targetm.strip_name_encoding (name); if (strcmp (name, IDENTIFIER_POINTER (newname))) warning (0, "#pragma redefine_extname ignored due to conflict with " "previous rename"); } else change_decl_assembler_name (decl, newname); } else /* We have to add this to the rename list even if there's already a global value that doesn't meet the above criteria, because in C++ "struct foo {...};" puts "foo" in the current namespace but does *not* conflict with a subsequent declaration of a function or variable foo. See g++.dg/other/pragma-re-2.C. */ add_to_renaming_pragma_list (oldname, newname); } /* This is called from here and from ia64.c. */ void add_to_renaming_pragma_list (tree oldname, tree newname) { tree previous = purpose_member (oldname, pending_redefine_extname); if (previous) { if (TREE_VALUE (previous) != newname) warning (0, "#pragma redefine_extname ignored due to conflict with " "previous #pragma redefine_extname"); return; } pending_redefine_extname = tree_cons (oldname, newname, pending_redefine_extname); } static GTY(()) tree pragma_extern_prefix; /* #pragma extern_prefix "prefix" */ static void handle_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy)) { tree prefix, x; enum cpp_ttype t; if (c_lex (&prefix) != CPP_STRING) GCC_BAD ("malformed #pragma extern_prefix, ignored"); t = c_lex (&x); if (t != CPP_EOF) warning (0, "junk at end of #pragma extern_prefix"); if (targetm.handle_pragma_extern_prefix) /* Note that the length includes the null terminator. */ pragma_extern_prefix = (TREE_STRING_LENGTH (prefix) > 1 ? prefix : NULL); else if (warn_unknown_pragmas > in_system_header) warning (OPT_Wunknown_pragmas, "#pragma extern_prefix not supported on this target"); } /* Hook from the front ends to apply the results of one of the preceding pragmas that rename variables. */ tree maybe_apply_renaming_pragma (tree decl, tree asmname) { tree *p, t; /* The renaming pragmas are only applied to declarations with external linkage. */ if ((TREE_CODE (decl) != FUNCTION_DECL && TREE_CODE (decl) != VAR_DECL) || (!TREE_PUBLIC (decl) && !DECL_EXTERNAL (decl)) || !has_c_linkage (decl)) return asmname; /* If the DECL_ASSEMBLER_NAME is already set, it does not change, but we may warn about a rename that conflicts. */ if (DECL_ASSEMBLER_NAME_SET_P (decl)) { const char *oldname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)); oldname = targetm.strip_name_encoding (oldname); if (asmname && strcmp (TREE_STRING_POINTER (asmname), oldname)) warning (0, "asm declaration ignored due to " "conflict with previous rename"); /* Take any pending redefine_extname off the list. */ for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t)) if (DECL_NAME (decl) == TREE_PURPOSE (t)) { /* Only warn if there is a conflict. */ if (strcmp (IDENTIFIER_POINTER (TREE_VALUE (t)), oldname)) warning (0, "#pragma redefine_extname ignored due to " "conflict with previous rename"); *p = TREE_CHAIN (t); break; } return 0; } /* Find out if we have a pending #pragma redefine_extname. */ for (p = &pending_redefine_extname; (t = *p); p = &TREE_CHAIN (t)) if (DECL_NAME (decl) == TREE_PURPOSE (t)) { tree newname = TREE_VALUE (t); *p = TREE_CHAIN (t); /* If we already have an asmname, #pragma redefine_extname is ignored (with a warning if it conflicts). */ if (asmname) { if (strcmp (TREE_STRING_POINTER (asmname), IDENTIFIER_POINTER (newname)) != 0) warning (0, "#pragma redefine_extname ignored due to " "conflict with __asm__ declaration"); return asmname; } /* Otherwise we use what we've got; #pragma extern_prefix is silently ignored. */ return build_string (IDENTIFIER_LENGTH (newname), IDENTIFIER_POINTER (newname)); } /* If we've got an asmname, #pragma extern_prefix is silently ignored. */ if (asmname) return asmname; /* If #pragma extern_prefix is in effect, apply it. */ if (pragma_extern_prefix) { const char *prefix = TREE_STRING_POINTER (pragma_extern_prefix); size_t plen = TREE_STRING_LENGTH (pragma_extern_prefix) - 1; const char *id = IDENTIFIER_POINTER (DECL_NAME (decl)); size_t ilen = IDENTIFIER_LENGTH (DECL_NAME (decl)); char *newname = (char *) alloca (plen + ilen + 1); memcpy (newname, prefix, plen); memcpy (newname + plen, id, ilen + 1); return build_string (plen + ilen, newname); } /* Nada. */ return 0; } #ifdef HANDLE_PRAGMA_VISIBILITY static void handle_pragma_visibility (cpp_reader *); typedef enum symbol_visibility visibility; DEF_VEC_I (visibility); DEF_VEC_ALLOC_I (visibility, heap); /* Sets the default visibility for symbols to something other than that specified on the command line. */ static void handle_pragma_visibility (cpp_reader *dummy ATTRIBUTE_UNUSED) { /* Form is #pragma GCC visibility push(hidden)|pop */ tree x; enum cpp_ttype token; enum { bad, push, pop } action = bad; static VEC (visibility, heap) *visstack; token = c_lex (&x); if (token == CPP_NAME) { const char *op = IDENTIFIER_POINTER (x); if (!strcmp (op, "push")) action = push; else if (!strcmp (op, "pop")) action = pop; } if (bad == action) GCC_BAD ("#pragma GCC visibility must be followed by push or pop"); else { if (pop == action) { if (!VEC_length (visibility, visstack)) { GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>"); } else { default_visibility = VEC_pop (visibility, visstack); visibility_options.inpragma = VEC_length (visibility, visstack) != 0; } } else { if (c_lex (&x) != CPP_OPEN_PAREN) GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored"); token = c_lex (&x); if (token != CPP_NAME) { GCC_BAD ("malformed #pragma GCC visibility push"); } else { const char *str = IDENTIFIER_POINTER (x); VEC_safe_push (visibility, heap, visstack, default_visibility); if (!strcmp (str, "default")) default_visibility = VISIBILITY_DEFAULT; else if (!strcmp (str, "internal")) default_visibility = VISIBILITY_INTERNAL; else if (!strcmp (str, "hidden")) default_visibility = VISIBILITY_HIDDEN; else if (!strcmp (str, "protected")) default_visibility = VISIBILITY_PROTECTED; else { GCC_BAD ("#pragma GCC visibility push() must specify default, internal, hidden or protected"); } visibility_options.inpragma = 1; } if (c_lex (&x) != CPP_CLOSE_PAREN) GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored"); } } if (c_lex (&x) != CPP_EOF) warning (0, "junk at end of %<#pragma GCC visibility%>"); } #endif /* Front-end wrappers for pragma registration to avoid dragging cpplib.h in almost everywhere. */ void c_register_pragma (const char *space, const char *name, void (*handler) (struct cpp_reader *)) { cpp_register_pragma (parse_in, space, name, handler, 0); } void c_register_pragma_with_expansion (const char *space, const char *name, void (*handler) (struct cpp_reader *)) { cpp_register_pragma (parse_in, space, name, handler, 1); } /* Set up front-end pragmas. */ void init_pragma (void) { #ifdef HANDLE_PRAGMA_PACK #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION c_register_pragma_with_expansion (0, "pack", handle_pragma_pack); #else c_register_pragma (0, "pack", handle_pragma_pack); #endif #endif #ifdef HANDLE_PRAGMA_WEAK c_register_pragma (0, "weak", handle_pragma_weak); #endif #ifdef HANDLE_PRAGMA_VISIBILITY c_register_pragma ("GCC", "visibility", handle_pragma_visibility); #endif c_register_pragma (0, "redefine_extname", handle_pragma_redefine_extname); c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix); c_register_pragma ("GCC", "pch_preprocess", c_common_pch_pragma); #ifdef REGISTER_TARGET_PRAGMAS REGISTER_TARGET_PRAGMAS (); #endif } #include "gt-c-pragma.h"