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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,

   2006, 2007, 2008 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 3, 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 COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#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"

#include "diagnostic.h"

#include "opts.h"

#include "plugin.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 GTY(()) align_stack {

  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_NEW (align_stack);

  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, %E) encountered without matching #pragma pack(push, %E)"

                 , id, 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 (pragma_lex (&x) != CPP_OPEN_PAREN)

    GCC_BAD ("missing %<(%> after %<#pragma pack%> - ignored");

  token = pragma_lex (&x);

  if (token == CPP_CLOSE_PAREN)

    {

      action = set;

      align = initial_max_fld_align;

    }

  else if (token == CPP_NUMBER)

    {

      if (TREE_CODE (x) != INTEGER_CST)

        GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");

      align = TREE_INT_CST_LOW (x);

      action = set;

      if (pragma_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 %qE for %<#pragma pack%> - ignored", x);

      while ((token = pragma_lex (&x)) == CPP_COMMA)

        {

          token = pragma_lex (&x);

          if (token == CPP_NAME && id == 0)

            {

              id = x;

            }

          else if (token == CPP_NUMBER && action == push && align == -1)

            {

              if (TREE_CODE (x) != INTEGER_CST)

                GCC_BAD ("invalid constant in %<#pragma pack%> - ignored");

              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 (pragma_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 (UNKNOWN_LOCATION,

                         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 (pragma_lex (&name) != CPP_NAME)

    GCC_BAD ("malformed #pragma weak, ignored");

  t = pragma_lex (&x);

  if (t == CPP_EQ)

    {

      if (pragma_lex (&value) != CPP_NAME)

        GCC_BAD ("malformed #pragma weak, ignored");

      t = pragma_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 (pragma_lex (&oldname) != CPP_NAME)

    GCC_BAD ("malformed #pragma redefine_extname, ignored");

  if (pragma_lex (&newname) != CPP_NAME)

    GCC_BAD ("malformed #pragma redefine_extname, ignored");

  t = pragma_lex (&x);

  if (t != CPP_EOF)

    warning (OPT_Wpragmas, "junk at end of %<#pragma redefine_extname%>");

  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 (pragma_lex (&prefix) != CPP_STRING)

    GCC_BAD ("malformed #pragma extern_prefix, ignored");

  t = pragma_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 *);

static VEC (int, heap) *visstack;

/* Push the visibility indicated by STR onto the top of the #pragma

   visibility stack.  KIND is 0 for #pragma GCC visibility, 1 for

   C++ namespace with visibility attribute and 2 for C++ builtin

   ABI namespace.  push_visibility/pop_visibility calls must have

   matching KIND, it is not allowed to push visibility using one

   KIND and pop using a different one.  */

void

push_visibility (const char *str, int kind)

{

  VEC_safe_push (int, heap, visstack,

                 ((int) default_visibility) | (kind << 8));

  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;

}

/* Pop a level of the #pragma visibility stack.  Return true if

   successful.  */

bool

pop_visibility (int kind)

{

  if (!VEC_length (int, visstack))

    return false;

  if ((VEC_last (int, visstack) >> 8) != kind)

    return false;

  default_visibility

    = (enum symbol_visibility) (VEC_pop (int, visstack) & 0xff);

  visibility_options.inpragma

    = VEC_length (int, visstack) != 0;

  return true;

}

/* 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;

  token = pragma_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 (! pop_visibility (0))

            GCC_BAD ("no matching push for %<#pragma GCC visibility pop%>");

        }

      else

        {

          if (pragma_lex (&x) != CPP_OPEN_PAREN)

            GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");

          token = pragma_lex (&x);

          if (token != CPP_NAME)

            GCC_BAD ("malformed #pragma GCC visibility push");

          else

            push_visibility (IDENTIFIER_POINTER (x), 0);

          if (pragma_lex (&x) != CPP_CLOSE_PAREN)

            GCC_BAD ("missing %<(%> after %<#pragma GCC visibility push%> - ignored");

        }

    }

  if (pragma_lex (&x) != CPP_EOF)

    warning (OPT_Wpragmas, "junk at end of %<#pragma GCC visibility%>");

}

#endif

static void

handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))

{

  const char *kind_string, *option_string;

  unsigned int option_index;

  enum cpp_ttype token;

  diagnostic_t kind;

  tree x;