winnt.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

/* Subroutines for insn-output.c for Windows NT.
   Contributed by Douglas Rupp ([e-mail])
   Copyright (C) 1995, 1997, 1998, 1999, 2000, 2001, 2002, 2003
   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, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "output.h"
#include "tree.h"
#include "flags.h"
#include "tm_p.h"
#include "toplev.h"
#include "hashtab.h"
#include "ggc.h"

/* i386/PE specific attribute support.

   i386/PE has two new attributes:
   dllexport - for exporting a function/variable that will live in a dll
   dllimport - for importing a function/variable from a dll

   Microsoft allows multiple declspecs in one __declspec, separating
   them with spaces.  We do NOT support this.  Instead, use __declspec
   multiple times.
*/

static tree associated_type PARAMS ((tree));
const char * gen_stdcall_suffix PARAMS ((tree));
int i386_pe_dllexport_p PARAMS ((tree));
int i386_pe_dllimport_p PARAMS ((tree));
void i386_pe_mark_dllexport PARAMS ((tree));
void i386_pe_mark_dllimport PARAMS ((tree));

/* Handle a "dllimport" or "dllexport" attribute;
   arguments as in struct attribute_spec.handler.  */
tree
ix86_handle_dll_attribute (pnode, name, args, flags, no_add_attrs)
     tree * pnode;
     tree name;
     tree args;
     int flags;
     bool *no_add_attrs;
{
  tree node = *pnode;

  /* These attributes may apply to structure and union types being created,
     but otherwise should pass to the declaration involved.  */
  if (!DECL_P (node))
    {
      if (flags & ((int) ATTR_FLAG_DECL_NEXT | (int) ATTR_FLAG_FUNCTION_NEXT
		   | (int) ATTR_FLAG_ARRAY_NEXT))
	{
	  *no_add_attrs = true;
	  return tree_cons (name, args, NULL_TREE);
	}
      if (TREE_CODE (node) != RECORD_TYPE && TREE_CODE (node) != UNION_TYPE)
	{
	  warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
	  *no_add_attrs = true;
	}

      return NULL_TREE;
    }

  /* Report error on dllimport ambiguities seen now before they cause
     any damage.  */
  else if (is_attribute_p ("dllimport", name))
    {
      /* Like MS, treat definition of dllimported variables and
	 non-inlined functions on declaration as syntax errors.
	 We allow the attribute for function definitions if declared
	 inline, but just ignore it in i386_pe_dllimport_p.  */
      if (TREE_CODE (node) == FUNCTION_DECL  && DECL_INITIAL (node)
          && !DECL_INLINE (node))
	{
	  error_with_decl (node, "function `%s' definition is marked dllimport.");
	  *no_add_attrs = true;
	}

      else if (TREE_CODE (node) == VAR_DECL)
	{
	  if (DECL_INITIAL (node))
	    {
	      error_with_decl (node,"variable `%s' definition is marked dllimport.");
	      *no_add_attrs = true;
	    }

	  /* `extern' needn't be specified with dllimport.
	     Specify `extern' now and hope for the best.  Sigh.  */
	  DECL_EXTERNAL (node) = 1; 
	  /* Also, implicitly give dllimport'd variables declared within
	     a function global scope, unless declared static.  */
	  if (current_function_decl != NULL_TREE && !TREE_STATIC (node))
  	    TREE_PUBLIC (node) = 1;
	}
    }

  /*  Report error if symbol is not accessible at global scope. */
  if (!TREE_PUBLIC (node)
      && (TREE_CODE (node) == VAR_DECL
	  || TREE_CODE (node) == FUNCTION_DECL)) 
    {
      error_with_decl (node, "external linkage required for symbol '%s' because of '%s' attribute.",
		       IDENTIFIER_POINTER (name));
      *no_add_attrs = true;
    }

  return NULL_TREE;
}

/* Handle a "shared" attribute;
   arguments as in struct attribute_spec.handler.  */
tree
ix86_handle_shared_attribute (node, name, args, flags, no_add_attrs)
     tree *node;
     tree name;
     tree args ATTRIBUTE_UNUSED;
     int flags ATTRIBUTE_UNUSED;
     bool *no_add_attrs;
{
  if (TREE_CODE (*node) != VAR_DECL)
    {
      warning ("`%s' attribute only applies to variables",
	       IDENTIFIER_POINTER (name));
      *no_add_attrs = true;
    }

  return NULL_TREE;
}

/* Return the type that we should use to determine if DECL is
   imported or exported.  */

static tree
associated_type (decl)
     tree decl;
{
  tree t = NULL_TREE;

  /* In the C++ frontend, DECL_CONTEXT for a method doesn't actually refer
     to the containing class.  So we look at the 'this' arg.  */
  if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE)
    {
      /* Artificial methods are not affected by the import/export status of
	 their class unless they are virtual.  */
      if (! DECL_ARTIFICIAL (decl) || DECL_VINDEX (decl))
	t = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (decl))));
    }
  else if (DECL_CONTEXT (decl)
	   && TREE_CODE_CLASS (TREE_CODE (DECL_CONTEXT (decl))) == 't')
    t = DECL_CONTEXT (decl);

  return t;
}

/* Return nonzero if DECL is a dllexport'd object.  */

int
i386_pe_dllexport_p (decl)
     tree decl;
{
  tree exp;

  if (TREE_CODE (decl) != VAR_DECL
      && TREE_CODE (decl) != FUNCTION_DECL)
    return 0;
  exp = lookup_attribute ("dllexport", DECL_ATTRIBUTES (decl));
  if (exp)
    return 1;

  /* Class members get the dllexport status of their class.  */
  if (associated_type (decl))
    {
      exp = lookup_attribute ("dllexport",
			      TYPE_ATTRIBUTES (associated_type (decl)));
      if (exp)
	return 1;
    }

  return 0;
}

/* Return nonzero if DECL is a dllimport'd object.  */

int
i386_pe_dllimport_p (decl)
     tree decl;
{
  tree imp;
  int context_imp = 0;

  if (TREE_CODE (decl) == FUNCTION_DECL
      && TARGET_NOP_FUN_DLLIMPORT)
    return 0;

  if (TREE_CODE (decl) != VAR_DECL
      && TREE_CODE (decl) != FUNCTION_DECL)
    return 0;

  imp = lookup_attribute ("dllimport", DECL_ATTRIBUTES (decl));

  /* Class members get the dllimport status of their class.  */
  if (!imp && associated_type (decl))
    {
      imp = lookup_attribute ("dllimport",
			      TYPE_ATTRIBUTES (associated_type (decl)));
      if (imp)
	context_imp = 1;
    }

  if (imp)
    {
      /* Don't mark defined functions as dllimport.  If the definition
	 itself was marked with dllimport, than ix86_handle_dll_attribute
	 reports an error. This handles the case when the definition
	 overrides an earlier declaration.  */
      if (TREE_CODE (decl) ==  FUNCTION_DECL && DECL_INITIAL (decl)
	  && !DECL_INLINE (decl))
	{
	   /* Don't warn about artificial methods.  */
	  if (!DECL_ARTIFICIAL (decl))
	    warning_with_decl (decl,"function '%s' is defined after prior declaration as dllimport: attribute ignored.");
	  return 0;
	}

      /* We ignore the dllimport attribute for inline member functions.
	 This differs from MSVC behaviour which treats it like GNUC
     	 'extern inline' extension.   */
      else if (TREE_CODE (decl) == FUNCTION_DECL && DECL_INLINE (decl))
        {
	  if (extra_warnings)
	    warning_with_decl (decl, "inline function '%s' is declared as dllimport: attribute ignored.");
	  return 0;
	}

      /*  Don't allow definitions of static data members in dllimport class,
	  Just ignore attribute for vtable data.  */
      else if (TREE_CODE (decl) == VAR_DECL
	       && TREE_STATIC (decl) && TREE_PUBLIC (decl)
	       && !DECL_EXTERNAL (decl) && context_imp)
	{
	  if (!DECL_VIRTUAL_P (decl))
	      error_with_decl (decl, "definition of static data member '%s' of dllimport'd class.");
           return 0;
	}

      /* Since we can't treat a pointer to a dllimport'd symbol as a
	 constant address, we turn off the attribute on C++ virtual
	 methods to allow creation of vtables using thunks. */
      else if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE
	       && (DECL_VIRTUAL_P (decl)))
           return 0;

      return 1;
    }

  return 0;
}

/* Return nonzero if SYMBOL is marked as being dllexport'd.  */

int
i386_pe_dllexport_name_p (symbol)
     const char *symbol;
{
  return symbol[0] == DLL_IMPORT_EXPORT_PREFIX
         && symbol[1] == 'e' && symbol[2] == '.';
}

/* Return nonzero if SYMBOL is marked as being dllimport'd.  */

int
i386_pe_dllimport_name_p (symbol)
     const char *symbol;
{
  return symbol[0] == DLL_IMPORT_EXPORT_PREFIX
         && symbol[1] == 'i' && symbol[2] == '.';
}

/* Mark a DECL as being dllexport'd.
   Note that we override the previous setting (eg: dllimport).  */

void
i386_pe_mark_dllexport (decl)
     tree decl;
{
  const char *oldname;
  char  *newname;
  rtx rtlname;
  tree idp;

  rtlname = XEXP (DECL_RTL (decl), 0);
  if (GET_CODE (rtlname) == SYMBOL_REF)
    oldname = XSTR (rtlname, 0);
  else if (GET_CODE (rtlname) == MEM
	   && GET_CODE (XEXP (rtlname, 0)) == SYMBOL_REF)
    oldname = XSTR (XEXP (rtlname, 0), 0);
  else
    abort ();
  if (i386_pe_dllimport_name_p (oldname))
    {
      warning_with_decl (decl,"inconsistent dll linkage for '%s': dllexport assumed.");
     /* Remove DLL_IMPORT_PREFIX.  */
      oldname += 9;
      DECL_NON_ADDR_CONST_P (decl) = 0;
    }
  else if (i386_pe_dllexport_name_p (oldname))
    return; /* already done */

  newname = alloca (strlen (oldname) + 4);
  sprintf (newname, "%ce.%s", DLL_IMPORT_EXPORT_PREFIX, oldname);

  /* We pass newname through get_identifier to ensure it has a unique
     address.  RTL processing can sometimes peek inside the symbol ref
     and compare the string's addresses to see if two symbols are
     identical.  */
  idp = get_identifier (newname);

  XEXP (DECL_RTL (decl), 0) =
    gen_rtx (SYMBOL_REF, Pmode, IDENTIFIER_POINTER (idp));
}

/* Mark a DECL as being dllimport'd.  */

void
i386_pe_mark_dllimport (decl)
     tree decl;
{
  const char *oldname;
  char  *newname;
  tree idp;
  rtx rtlname, newrtl;

  rtlname = XEXP (DECL_RTL (decl), 0);
  if (GET_CODE (rtlname) == SYMBOL_REF)
    oldname = XSTR (rtlname, 0);
  else if (GET_CODE (rtlname) == MEM
	   && GET_CODE (XEXP (rtlname, 0)) == SYMBOL_REF)
    oldname = XSTR (XEXP (rtlname, 0), 0);
  else
    abort ();
  if (i386_pe_dllexport_name_p (oldname))
    {
      error ("`%s' declared as both exported to and imported from a DLL",
             IDENTIFIER_POINTER (DECL_NAME (decl)));
      return;
    }
  else if (i386_pe_dllimport_name_p (oldname))
    {
      /* Already done, but do a sanity check to prevent assembler errors. */
      if (!DECL_EXTERNAL (decl) || !TREE_PUBLIC (decl))
	{
	  error_with_decl (decl, "failure in redeclaration of '%s': dllimport'd symbol lacks external linkage.");
	  abort();
	}
    return;
    }

  newname = alloca (strlen (oldname) + 11);
  sprintf (newname, "%ci._imp__%s", DLL_IMPORT_EXPORT_PREFIX, oldname);

  /* We pass newname through get_identifier to ensure it has a unique
     address.  RTL processing can sometimes peek inside the symbol ref