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/* 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 (OPT_Wpragmas, gmsgid); return; } while (0)

#define GCC_BAD2(gmsgid, arg) \

  do { warning (OPT_Wpragmas, 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(<n>) in effect when the first

   #pragma pack(push,<n>) 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

     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 (OPT_Wpragmas, "\

#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], <n>) is not supported on this target")

#define pop_alignment(ID) \

    GCC_BAD ("#pragma pack(pop[, id], <n>) 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][, <n>])%> - 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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "#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 (OPT_Wpragmas, "#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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "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 (OPT_Wpragmas, "#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 (OPT_Wpragmas, "#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 (OPT_Wpragmas, "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