2011-10-08 Paul Thomas <pault@gcc.gnu.org>

[official-gcc.git] / gcc / c-family / c-pragma.c

/* 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, 2009, 2010 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 "tree.h"
#include "function.h"           /* For cfun.  FIXME: Does the parser know
                                   when it is inside a function, so that
                                   we don't have to look at cfun?  */
#include "cpplib.h"
#include "c-pragma.h"
#include "flags.h"
#include "c-common.h"
#include "output.h"
#include "tm_p.h"               /* For REGISTER_TARGET_PRAGMAS (why is
                                   this not a target hook?).  */
#include "vec.h"
#include "vecprim.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;

static void handle_pragma_pack (cpp_reader *);

/* 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_align_stack ();

  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(<n>) 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 (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;
}

/* #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;
    }
}

typedef struct GTY(()) pending_weak_d
{
  tree name;
  tree value;
} pending_weak;

DEF_VEC_O(pending_weak);
DEF_VEC_ALLOC_O(pending_weak,gc);

static GTY(()) VEC(pending_weak,gc) *pending_weaks;

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 id;
  int i;
  pending_weak *pe;

  /* 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_EACH_VEC_ELT (pending_weak, pending_weaks, i, pe)
    if (id == pe->name)
      {
        apply_pragma_weak (decl, pe->value);
        VEC_unordered_remove (pending_weak, pending_weaks, i);
        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 alias_id, id, decl;
  int i;
  pending_weak *pe;

  FOR_EACH_VEC_ELT (pending_weak, pending_weaks, i, pe)
    {
      alias_id = pe->name;
      id = pe->value;

      if (id == 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_weak *pe;
      pe = VEC_safe_push (pending_weak, gc, pending_weaks, NULL);
      pe->name = name;
      pe->value = value;
    }
}

/* 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.)  */

typedef struct GTY(()) pending_redefinition_d {
  tree oldname;
  tree newname;
} pending_redefinition;

DEF_VEC_O(pending_redefinition);
DEF_VEC_ALLOC_O(pending_redefinition,gc);

static GTY(()) VEC(pending_redefinition,gc) *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, decls, x;
  enum cpp_ttype t;
  bool found;

  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%>");

  found = false;
  for (decls = c_linkage_bindings (oldname);
       decls; )
    {
      tree decl;
      if (TREE_CODE (decls) == TREE_LIST)
        {
          decl = TREE_VALUE (decls);
          decls = TREE_CHAIN (decls);
        }
      else
        {
          decl = decls;
          decls = NULL_TREE;
        }

      if ((TREE_PUBLIC (decl) || DECL_EXTERNAL (decl))
          && (TREE_CODE (decl) == FUNCTION_DECL
              || TREE_CODE (decl) == VAR_DECL))
        {
          found = true;
          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);
        }
    }

  if (!found)
    /* 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)
{
  unsigned ix;
  pending_redefinition *p;

  FOR_EACH_VEC_ELT (pending_redefinition, pending_redefine_extname, ix, p)
    if (oldname == p->oldname)
      {
        if (p->newname != newname)
          warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
                   "conflict with previous #pragma redefine_extname");
        return;
      }

  p = VEC_safe_push (pending_redefinition, gc, pending_redefine_extname, NULL);
  p->oldname = oldname;
  p->newname = newname;
}

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)
{
  unsigned ix;
  pending_redefinition *p;

  /* 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_EACH_VEC_ELT (pending_redefinition, pending_redefine_extname, ix, p)
        if (DECL_NAME (decl) == p->oldname)
          {
            /* Only warn if there is a conflict.  */
            if (strcmp (IDENTIFIER_POINTER (p->newname), oldname))
              warning (OPT_Wpragmas, "#pragma redefine_extname ignored due to "
                       "conflict with previous rename");

            VEC_unordered_remove (pending_redefinition,
                                  pending_redefine_extname, ix);
            break;
          }
      return 0;
    }

  /* Find out if we have a pending #pragma redefine_extname.  */
  FOR_EACH_VEC_ELT (pending_redefinition, pending_redefine_extname, ix, p)
    if (DECL_NAME (decl) == p->oldname)
      {
        tree newname = p->newname;
        VEC_unordered_remove (pending_redefinition,
                              pending_redefine_extname, ix);

        /* 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;
}


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%>");
}

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;
  struct cl_option_handlers handlers;

  token = pragma_lex (&x);
  if (token != CPP_NAME)
    GCC_BAD ("missing [error|warning|ignored] after %<#pragma GCC diagnostic%>");
  kind_string = IDENTIFIER_POINTER (x);
  if (strcmp (kind_string, "error") == 0)
    kind = DK_ERROR;
  else if (strcmp (kind_string, "warning") == 0)
    kind = DK_WARNING;
  else if (strcmp (kind_string, "ignored") == 0)
    kind = DK_IGNORED;
  else if (strcmp (kind_string, "push") == 0)
    {
      diagnostic_push_diagnostics (global_dc, input_location);
      return;
    }
  else if (strcmp (kind_string, "pop") == 0)
    {
      diagnostic_pop_diagnostics (global_dc, input_location);
      return;
    }
  else
    GCC_BAD ("expected [error|warning|ignored|push|pop] after %<#pragma GCC diagnostic%>");

  token = pragma_lex (&x);
  if (token != CPP_STRING)
    GCC_BAD ("missing option after %<#pragma GCC diagnostic%> kind");
  option_string = TREE_STRING_POINTER (x);
  set_default_handlers (&handlers);
  for (option_index = 0; option_index < cl_options_count; option_index++)
    if (strcmp (cl_options[option_index].opt_text, option_string) == 0)
      {
        control_warning_option (option_index, (int) kind, kind != DK_IGNORED,
                                input_location, c_family_lang_mask, &handlers,
                                &global_options, &global_options_set,
                                global_dc);
        return;
      }
  GCC_BAD ("unknown option after %<#pragma GCC diagnostic%> kind");
}

/*  Parse #pragma GCC target (xxx) to set target specific options.  */
static void
handle_pragma_target(cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x;
  bool close_paren_needed_p = false;

  if (cfun)
    {
      error ("#pragma GCC option is not allowed inside functions");
      return;
    }

  token = pragma_lex (&x);
  if (token == CPP_OPEN_PAREN)
    {
      close_paren_needed_p = true;
      token = pragma_lex (&x);
    }

  if (token != CPP_STRING)
    {
      GCC_BAD ("%<#pragma GCC option%> is not a string");
      return;
    }

  /* Strings are user options.  */
  else
    {
      tree args = NULL_TREE;

      do
        {
          /* Build up the strings now as a tree linked list.  Skip empty
             strings.  */
          if (TREE_STRING_LENGTH (x) > 0)
            args = tree_cons (NULL_TREE, x, args);

          token = pragma_lex (&x);
          while (token == CPP_COMMA)
            token = pragma_lex (&x);
        }
      while (token == CPP_STRING);

      if (close_paren_needed_p)
        {
          if (token == CPP_CLOSE_PAREN)
            token = pragma_lex (&x);
          else
            GCC_BAD ("%<#pragma GCC target (string [,string]...)%> does "
                     "not have a final %<)%>");
        }

      if (token != CPP_EOF)
        {
          error ("#pragma GCC target string... is badly formed");
          return;
        }

      /* put arguments in the order the user typed them.  */
      args = nreverse (args);

      if (targetm.target_option.pragma_parse (args, NULL_TREE))
        current_target_pragma = args;
    }
}

/* Handle #pragma GCC optimize to set optimization options.  */
static void
handle_pragma_optimize (cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x;
  bool close_paren_needed_p = false;
  tree optimization_previous_node = optimization_current_node;

  if (cfun)
    {
      error ("#pragma GCC optimize is not allowed inside functions");
      return;
    }

  token = pragma_lex (&x);
  if (token == CPP_OPEN_PAREN)
    {
      close_paren_needed_p = true;
      token = pragma_lex (&x);
    }

  if (token != CPP_STRING && token != CPP_NUMBER)
    {
      GCC_BAD ("%<#pragma GCC optimize%> is not a string or number");
      return;
    }

  /* Strings/numbers are user options.  */
  else
    {
      tree args = NULL_TREE;

      do
        {
          /* Build up the numbers/strings now as a list.  */
          if (token != CPP_STRING || TREE_STRING_LENGTH (x) > 0)
            args = tree_cons (NULL_TREE, x, args);

          token = pragma_lex (&x);
          while (token == CPP_COMMA)
            token = pragma_lex (&x);
        }
      while (token == CPP_STRING || token == CPP_NUMBER);

      if (close_paren_needed_p)
        {
          if (token == CPP_CLOSE_PAREN)
            token = pragma_lex (&x);
          else
            GCC_BAD ("%<#pragma GCC optimize (string [,string]...)%> does "
                     "not have a final %<)%>");
        }

      if (token != CPP_EOF)
        {
          error ("#pragma GCC optimize string... is badly formed");
          return;
        }

      /* put arguments in the order the user typed them.  */
      args = nreverse (args);

      parse_optimize_options (args, false);
      current_optimize_pragma = chainon (current_optimize_pragma, args);
      optimization_current_node = build_optimization_node ();
      c_cpp_builtins_optimize_pragma (parse_in,
                                      optimization_previous_node,
                                      optimization_current_node);
    }
}

/* Stack of the #pragma GCC options created with #pragma GCC push_option.  Save
   both the binary representation of the options and the TREE_LIST of
   strings that will be added to the function's attribute list.  */
typedef struct GTY(()) opt_stack {
  struct opt_stack *prev;
  tree target_binary;
  tree target_strings;
  tree optimize_binary;
  tree optimize_strings;
} opt_stack;

static GTY(()) struct opt_stack * options_stack;

/* Handle #pragma GCC push_options to save the current target and optimization
   options.  */

static void
handle_pragma_push_options (cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x = 0;
  opt_stack *p;

  token = pragma_lex (&x);
  if (token != CPP_EOF)
    {
      warning (OPT_Wpragmas, "junk at end of %<#pragma push_options%>");
      return;
    }

  p = ggc_alloc_opt_stack ();
  p->prev = options_stack;
  options_stack = p;

  /* Save optimization and target flags in binary format.  */
  p->optimize_binary = build_optimization_node ();
  p->target_binary = build_target_option_node ();

  /* Save optimization and target flags in string list format.  */
  p->optimize_strings = copy_list (current_optimize_pragma);
  p->target_strings = copy_list (current_target_pragma);
}

/* Handle #pragma GCC pop_options to restore the current target and
   optimization options from a previous push_options.  */

static void
handle_pragma_pop_options (cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x = 0;
  opt_stack *p;

  token = pragma_lex (&x);
  if (token != CPP_EOF)
    {
      warning (OPT_Wpragmas, "junk at end of %<#pragma pop_options%>");
      return;
    }

  if (! options_stack)
    {
      warning (OPT_Wpragmas,
               "%<#pragma GCC pop_options%> without a corresponding "
               "%<#pragma GCC push_options%>");
      return;
    }

  p = options_stack;
  options_stack = p->prev;

  if (p->target_binary != target_option_current_node)
    {
      (void) targetm.target_option.pragma_parse (NULL_TREE, p->target_binary);
      target_option_current_node = p->target_binary;
    }

  if (p->optimize_binary != optimization_current_node)
    {
      tree old_optimize = optimization_current_node;
      cl_optimization_restore (&global_options,
                               TREE_OPTIMIZATION (p->optimize_binary));
      c_cpp_builtins_optimize_pragma (parse_in, old_optimize,
                                      p->optimize_binary);
      optimization_current_node = p->optimize_binary;
    }

  current_target_pragma = p->target_strings;
  current_optimize_pragma = p->optimize_strings;
}

/* Handle #pragma GCC reset_options to restore the current target and
   optimization options to the original options used on the command line.  */

static void
handle_pragma_reset_options (cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x = 0;
  tree new_optimize = optimization_default_node;
  tree new_target = target_option_default_node;

  token = pragma_lex (&x);
  if (token != CPP_EOF)
    {
      warning (OPT_Wpragmas, "junk at end of %<#pragma reset_options%>");
      return;
    }

  if (new_target != target_option_current_node)
    {
      (void) targetm.target_option.pragma_parse (NULL_TREE, new_target);
      target_option_current_node = new_target;
    }

  if (new_optimize != optimization_current_node)
    {
      tree old_optimize = optimization_current_node;
      cl_optimization_restore (&global_options,
                               TREE_OPTIMIZATION (new_optimize));
      c_cpp_builtins_optimize_pragma (parse_in, old_optimize, new_optimize);
      optimization_current_node = new_optimize;
    }

  current_target_pragma = NULL_TREE;
  current_optimize_pragma = NULL_TREE;
}

/* Print a plain user-specified message.  */

static void
handle_pragma_message (cpp_reader *ARG_UNUSED(dummy))
{
  enum cpp_ttype token;
  tree x, message = 0;

  token = pragma_lex (&x);
  if (token == CPP_OPEN_PAREN)
    {
      token = pragma_lex (&x);
      if (token == CPP_STRING)
        message = x;
      else
        GCC_BAD ("expected a string after %<#pragma message%>");
      if (pragma_lex (&x) != CPP_CLOSE_PAREN)
        GCC_BAD ("malformed %<#pragma message%>, ignored");
    }
  else if (token == CPP_STRING)
    message = x;
  else
    GCC_BAD ("expected a string after %<#pragma message%>");

  gcc_assert (message);

  if (pragma_lex (&x) != CPP_EOF)
    warning (OPT_Wpragmas, "junk at end of %<#pragma message%>");

  if (TREE_STRING_LENGTH (message) > 1)
    inform (input_location, "#pragma message: %s", TREE_STRING_POINTER (message));
}

/* Mark whether the current location is valid for a STDC pragma.  */

static bool valid_location_for_stdc_pragma;

void
mark_valid_location_for_stdc_pragma (bool flag)
{
  valid_location_for_stdc_pragma = flag;
}

/* Return true if the current location is valid for a STDC pragma.  */

bool
valid_location_for_stdc_pragma_p (void)
{
  return valid_location_for_stdc_pragma;
}

enum pragma_switch_t { PRAGMA_ON, PRAGMA_OFF, PRAGMA_DEFAULT, PRAGMA_BAD };

/* A STDC pragma must appear outside of external declarations or
   preceding all explicit declarations and statements inside a compound
   statement; its behavior is undefined if used in any other context.
   It takes a switch of ON, OFF, or DEFAULT.  */

static enum pragma_switch_t
handle_stdc_pragma (const char *pname)
{
  const char *arg;
  tree t;
  enum pragma_switch_t ret;

  if (!valid_location_for_stdc_pragma_p ())
    {
      warning (OPT_Wpragmas, "invalid location for %<pragma %s%>, ignored",
               pname);
      return PRAGMA_BAD;
    }

  if (pragma_lex (&t) != CPP_NAME)
    {
      warning (OPT_Wpragmas, "malformed %<#pragma %s%>, ignored", pname);
      return PRAGMA_BAD;
    }

  arg = IDENTIFIER_POINTER (t);

  if (!strcmp (arg, "ON"))
    ret = PRAGMA_ON;
  else if (!strcmp (arg, "OFF"))
    ret = PRAGMA_OFF;
  else if (!strcmp (arg, "DEFAULT"))
    ret = PRAGMA_DEFAULT;
  else
    {
      warning (OPT_Wpragmas, "malformed %<#pragma %s%>, ignored", pname);
      return PRAGMA_BAD;
    }

  if (pragma_lex (&t) != CPP_EOF)
    {
      warning (OPT_Wpragmas, "junk at end of %<#pragma %s%>", pname);
      return PRAGMA_BAD;
    }

  return ret;
}

/* #pragma STDC FLOAT_CONST_DECIMAL64 ON
   #pragma STDC FLOAT_CONST_DECIMAL64 OFF
   #pragma STDC FLOAT_CONST_DECIMAL64 DEFAULT */

static void
handle_pragma_float_const_decimal64 (cpp_reader *ARG_UNUSED (dummy))
{
  if (c_dialect_cxx ())
    {
      if (warn_unknown_pragmas > in_system_header)
        warning (OPT_Wunknown_pragmas,
                 "%<#pragma STDC FLOAT_CONST_DECIMAL64%> is not supported"
                 " for C++");
      return;
    }

  if (!targetm.decimal_float_supported_p ())
    {
      if (warn_unknown_pragmas > in_system_header)
        warning (OPT_Wunknown_pragmas,
                 "%<#pragma STDC FLOAT_CONST_DECIMAL64%> is not supported"
                 " on this target");
      return;
    }

  pedwarn (input_location, OPT_pedantic,
           "ISO C does not support %<#pragma STDC FLOAT_CONST_DECIMAL64%>");

  switch (handle_stdc_pragma ("STDC FLOAT_CONST_DECIMAL64"))
    {
    case PRAGMA_ON:
      set_float_const_decimal64 ();
      break;
    case PRAGMA_OFF:
    case PRAGMA_DEFAULT:
      clear_float_const_decimal64 ();
      break;
    case PRAGMA_BAD:
      break;
    }
}

/* A vector of registered pragma callbacks, which is never freed.   */
DEF_VEC_O (internal_pragma_handler);
DEF_VEC_ALLOC_O (internal_pragma_handler, heap);

static VEC(internal_pragma_handler, heap) *registered_pragmas;

typedef struct
{
  const char *space;
  const char *name;
} pragma_ns_name;

DEF_VEC_O (pragma_ns_name);
DEF_VEC_ALLOC_O (pragma_ns_name, heap);

static VEC(pragma_ns_name, heap) *registered_pp_pragmas;

struct omp_pragma_def { const char *name; unsigned int id; };
static const struct omp_pragma_def omp_pragmas[] = {
  { "atomic", PRAGMA_OMP_ATOMIC },
  { "barrier", PRAGMA_OMP_BARRIER },
  { "critical", PRAGMA_OMP_CRITICAL },
  { "flush", PRAGMA_OMP_FLUSH },
  { "for", PRAGMA_OMP_FOR },
  { "master", PRAGMA_OMP_MASTER },
  { "ordered", PRAGMA_OMP_ORDERED },
  { "parallel", PRAGMA_OMP_PARALLEL },
  { "section", PRAGMA_OMP_SECTION },
  { "sections", PRAGMA_OMP_SECTIONS },
  { "single", PRAGMA_OMP_SINGLE },
  { "task", PRAGMA_OMP_TASK },
  { "taskwait", PRAGMA_OMP_TASKWAIT },
  { "taskyield", PRAGMA_OMP_TASKYIELD },
  { "threadprivate", PRAGMA_OMP_THREADPRIVATE }
};

void
c_pp_lookup_pragma (unsigned int id, const char **space, const char **name)
{
  const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
  int i;

  for (i = 0; i < n_omp_pragmas; ++i)
    if (omp_pragmas[i].id == id)
      {
        *space = "omp";
        *name = omp_pragmas[i].name;
        return;
      }

  if (id >= PRAGMA_FIRST_EXTERNAL
      && (id < PRAGMA_FIRST_EXTERNAL
          + VEC_length (pragma_ns_name, registered_pp_pragmas)))
    {
      *space = VEC_index (pragma_ns_name, registered_pp_pragmas,
                          id - PRAGMA_FIRST_EXTERNAL)->space;
      *name = VEC_index (pragma_ns_name, registered_pp_pragmas,
                         id - PRAGMA_FIRST_EXTERNAL)->name;
      return;
    }

  gcc_unreachable ();
}

/* Front-end wrappers for pragma registration to avoid dragging
   cpplib.h in almost everywhere.  */

static void
c_register_pragma_1 (const char *space, const char *name,
                     internal_pragma_handler ihandler, bool allow_expansion)
{
  unsigned id;

  if (flag_preprocess_only)
    {
      pragma_ns_name ns_name;

      if (!allow_expansion)
        return;

      ns_name.space = space;
      ns_name.name = name;
      VEC_safe_push (pragma_ns_name, heap, registered_pp_pragmas, &ns_name);
      id = VEC_length (pragma_ns_name, registered_pp_pragmas);
      id += PRAGMA_FIRST_EXTERNAL - 1;
    }
  else
    {
      VEC_safe_push (internal_pragma_handler, heap, registered_pragmas,
                     &ihandler);
      id = VEC_length (internal_pragma_handler, registered_pragmas);
      id += PRAGMA_FIRST_EXTERNAL - 1;

      /* The C++ front end allocates 6 bits in cp_token; the C front end
         allocates 7 bits in c_token.  At present this is sufficient.  */
      gcc_assert (id < 64);
    }

  cpp_register_deferred_pragma (parse_in, space, name, id,
                                allow_expansion, false);
}

/* Register a C pragma handler, using a space and a name.  It disallows pragma
   expansion (if you want it, use c_register_pragma_with_expansion instead).  */
void
c_register_pragma (const char *space, const char *name,
                   pragma_handler_1arg handler)
{
  internal_pragma_handler ihandler;

  ihandler.handler.handler_1arg = handler;
  ihandler.extra_data = false;
  ihandler.data = NULL;
  c_register_pragma_1 (space, name, ihandler, false);
}

/* Register a C pragma handler, using a space and a name, it also carries an
   extra data field which can be used by the handler.  It disallows pragma
   expansion (if you want it, use c_register_pragma_with_expansion_and_data
   instead).  */
void
c_register_pragma_with_data (const char *space, const char *name,
                             pragma_handler_2arg handler, void * data)
{
  internal_pragma_handler ihandler;

  ihandler.handler.handler_2arg = handler;
  ihandler.extra_data = true;
  ihandler.data = data;
  c_register_pragma_1 (space, name, ihandler, false);
}

/* Register a C pragma handler, using a space and a name.  It allows pragma
   expansion as in the following example:

   #define NUMBER 10
   #pragma count (NUMBER)

   Name expansion is still disallowed.  */
void
c_register_pragma_with_expansion (const char *space, const char *name,
                                  pragma_handler_1arg handler)
{
  internal_pragma_handler ihandler;

  ihandler.handler.handler_1arg = handler;
  ihandler.extra_data = false;
  ihandler.data = NULL;
  c_register_pragma_1 (space, name, ihandler, true);
}

/* Register a C pragma handler, using a space and a name, it also carries an
   extra data field which can be used by the handler.  It allows pragma
   expansion as in the following example:

   #define NUMBER 10
   #pragma count (NUMBER)

   Name expansion is still disallowed.  */
void
c_register_pragma_with_expansion_and_data (const char *space, const char *name,
                                           pragma_handler_2arg handler,
                                           void *data)
{
  internal_pragma_handler ihandler;

  ihandler.handler.handler_2arg = handler;
  ihandler.extra_data = true;
  ihandler.data = data;
  c_register_pragma_1 (space, name, ihandler, true);
}

void
c_invoke_pragma_handler (unsigned int id)
{
  internal_pragma_handler *ihandler;
  pragma_handler_1arg handler_1arg;
  pragma_handler_2arg handler_2arg;

  id -= PRAGMA_FIRST_EXTERNAL;
  ihandler = VEC_index (internal_pragma_handler, registered_pragmas, id);
  if (ihandler->extra_data)
    {
      handler_2arg = ihandler->handler.handler_2arg;
      handler_2arg (parse_in, ihandler->data);
    }
  else
    {
      handler_1arg = ihandler->handler.handler_1arg;
      handler_1arg (parse_in);
    }
}

/* Set up front-end pragmas.  */
void
init_pragma (void)
{
  if (flag_openmp)
    {
      const int n_omp_pragmas = sizeof (omp_pragmas) / sizeof (*omp_pragmas);
      int i;

      for (i = 0; i < n_omp_pragmas; ++i)
        cpp_register_deferred_pragma (parse_in, "omp", omp_pragmas[i].name,
                                      omp_pragmas[i].id, true, true);
    }

  if (!flag_preprocess_only)
    cpp_register_deferred_pragma (parse_in, "GCC", "pch_preprocess",
                                  PRAGMA_GCC_PCH_PREPROCESS, false, false);

#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
  c_register_pragma (0, "weak", handle_pragma_weak);
  c_register_pragma ("GCC", "visibility", handle_pragma_visibility);

  c_register_pragma ("GCC", "diagnostic", handle_pragma_diagnostic);
  c_register_pragma ("GCC", "target", handle_pragma_target);
  c_register_pragma ("GCC", "optimize", handle_pragma_optimize);
  c_register_pragma ("GCC", "push_options", handle_pragma_push_options);
  c_register_pragma ("GCC", "pop_options", handle_pragma_pop_options);
  c_register_pragma ("GCC", "reset_options", handle_pragma_reset_options);

  c_register_pragma ("STDC", "FLOAT_CONST_DECIMAL64",
                     handle_pragma_float_const_decimal64);

  c_register_pragma_with_expansion (0, "redefine_extname",
                                    handle_pragma_redefine_extname);
  c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);

  c_register_pragma_with_expansion (0, "message", handle_pragma_message);

#ifdef REGISTER_TARGET_PRAGMAS
  REGISTER_TARGET_PRAGMAS ();
#endif

  /* Allow plugins to register their own pragmas. */
  invoke_plugin_callbacks (PLUGIN_PRAGMAS, NULL);
}

#include "gt-c-family-c-pragma.h"