xref: /netbsd-6-1-5-RELEASE/gnu/dist/gcc4/gcc/config/i386/winnt.c

/* Subroutines for insn-output.c for Windows NT.
   Contributed by Douglas Rupp (drupp@cs.washington.edu)
   Copyright (C) 1995, 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 "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 (tree);
static tree gen_stdcall_or_fastcall_suffix (tree, bool);
static bool i386_pe_dllexport_p (tree);
static bool i386_pe_dllimport_p (tree);
static void i386_pe_mark_dllexport (tree);
static void i386_pe_mark_dllimport (tree);

/* This is we how mark internal identifiers with dllimport or dllexport
   attributes.  */
#ifndef DLL_IMPORT_PREFIX
#define DLL_IMPORT_PREFIX "#i."
#endif
#ifndef DLL_EXPORT_PREFIX
#define DLL_EXPORT_PREFIX "#e."
#endif

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

  return NULL_TREE;
}

/* Handle a "selectany" attribute;
   arguments as in struct attribute_spec.handler.  */
tree
ix86_handle_selectany_attribute (tree *node, tree name,
			         tree args ATTRIBUTE_UNUSED,
			         int flags ATTRIBUTE_UNUSED,
				 bool *no_add_attrs)
{
  /* The attribute applies only to objects that are initialized and have
     external linkage,  */
  if (TREE_CODE (*node) == VAR_DECL && TREE_PUBLIC (*node)
      && (DECL_INITIAL (*node)
          /* If an object is initialized with a ctor, the static
	     initialization and destruction code for it is present in
	     each unit defining the object.  The code that calls the
	     ctor is protected by a link-once guard variable, so that
	     the object still has link-once semantics,  */
    	  || TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (*node))))
    make_decl_one_only (*node);
  else
    {
      error ("%qs attribute applies only to initialized variables"
       	     " with external linkage",  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 (tree decl)
{
  return  (DECL_CONTEXT (decl) && TYPE_P (DECL_CONTEXT (decl)))
            ?  DECL_CONTEXT (decl) : NULL_TREE;
}


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

static bool
i386_pe_dllexport_p (tree decl)
{
  if (TREE_CODE (decl) != VAR_DECL
       && TREE_CODE (decl) != FUNCTION_DECL)
    return false;

  if (lookup_attribute ("dllexport", DECL_ATTRIBUTES (decl)))
    return true;

  /* Also mark class members of exported classes with dllexport.  */
  if (associated_type (decl)
      && lookup_attribute ("dllexport",
			    TYPE_ATTRIBUTES (associated_type (decl))))
    return i386_pe_type_dllexport_p (decl);

  return false;
}

static bool
i386_pe_dllimport_p (tree decl)
{
  if (TREE_CODE (decl) != VAR_DECL
       && TREE_CODE (decl) != FUNCTION_DECL)
    return false;

  /* Lookup the attribute rather than rely on the DECL_DLLIMPORT_P flag.
     We may need to override an earlier decision.  */
  if (lookup_attribute ("dllimport", DECL_ATTRIBUTES (decl)))
    return true;

  /* The DECL_DLLIMPORT_P flag was set for decls in the class definition
     by  targetm.cxx.adjust_class_at_definition.  Check again to emit
     warnings if the class attribute has been overriden by an
     out-of-class definition.  */
  if (associated_type (decl)
      && lookup_attribute ("dllimport",
			    TYPE_ATTRIBUTES (associated_type (decl))))
    return i386_pe_type_dllimport_p (decl);

  return false;
}

/* Handle the -mno-fun-dllimport target switch.  */
bool
i386_pe_valid_dllimport_attribute_p (tree decl)
{
   if (TARGET_NOP_FUN_DLLIMPORT && TREE_CODE (decl) == FUNCTION_DECL)
     return false;
   return true;
}

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

int
i386_pe_dllexport_name_p (const char *symbol)
{
  return (strncmp (DLL_EXPORT_PREFIX, symbol,
		   strlen (DLL_EXPORT_PREFIX)) == 0);
}

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

int
i386_pe_dllimport_name_p (const char *symbol)
{
  return (strncmp (DLL_IMPORT_PREFIX, symbol,
		   strlen (DLL_IMPORT_PREFIX)) == 0);
}

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

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

  rtlname = XEXP (DECL_RTL (decl), 0);
  if (GET_CODE (rtlname) == MEM)
    rtlname = XEXP (rtlname, 0);
  gcc_assert (GET_CODE (rtlname) == SYMBOL_REF);
  oldname = XSTR (rtlname, 0);
  if (i386_pe_dllimport_name_p (oldname))
    {
      warning (0, "inconsistent dll linkage for %q+D, dllexport assumed",
	       decl);
     /* Remove DLL_IMPORT_PREFIX.  */
      oldname += strlen (DLL_IMPORT_PREFIX);
    }
  else if (i386_pe_dllexport_name_p (oldname))
    return;  /*  already done  */

  newname = alloca (strlen (DLL_EXPORT_PREFIX) + strlen (oldname) + 1);
  sprintf (newname, "%s%s", DLL_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);

  symref = gen_rtx_SYMBOL_REF (Pmode, IDENTIFIER_POINTER (idp));
  SYMBOL_REF_DECL (symref) = decl;
  XEXP (DECL_RTL (decl), 0) = symref;
}

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

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

  rtlname = XEXP (DECL_RTL (decl), 0);
  if (GET_CODE (rtlname) == MEM)
    rtlname = XEXP (rtlname, 0);
  gcc_assert (GET_CODE (rtlname) == SYMBOL_REF);
  oldname = XSTR (rtlname, 0);
  if (i386_pe_dllexport_name_p (oldname))
    {
      error ("%qs 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.  */
      gcc_assert (DECL_EXTERNAL (decl) && TREE_PUBLIC (decl)
		  && DECL_DLLIMPORT_P (decl));
      return;
    }

  newname = alloca (strlen (DLL_IMPORT_PREFIX) + strlen (oldname) + 1);
  sprintf (newname, "%s%s", DLL_IMPORT_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);

  symref = gen_rtx_SYMBOL_REF (Pmode, IDENTIFIER_POINTER (idp));
  SYMBOL_REF_DECL (symref) = decl;
  newrtl = gen_rtx_MEM (Pmode,symref);
  XEXP (DECL_RTL (decl), 0) = newrtl;

  DECL_DLLIMPORT_P (decl) = 1;
}

/* Return string which is the former assembler name modified with a
   suffix consisting of an atsign (@) followed by the number of bytes of
   arguments.  If FASTCALL is true, also add the FASTCALL_PREFIX.  */

static tree
gen_stdcall_or_fastcall_suffix (tree decl, bool fastcall)
{
  int total = 0;
  /* ??? This probably should use XSTR (XEXP (DECL_RTL (decl), 0), 0) instead
     of DECL_ASSEMBLER_NAME.  */
   const char *asmname =  IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
  char *newsym;
  char *p;
  tree formal_type;

  /* Do not change the identifier if a verbatim asmspec or already done. */
  if (*asmname == '*' || strchr (asmname, '@'))
    return DECL_ASSEMBLER_NAME (decl);

  formal_type = TYPE_ARG_TYPES (TREE_TYPE (decl));
  if (formal_type != NULL_TREE)
    {
      /* These attributes are ignored for variadic functions in
	 i386.c:ix86_return_pops_args. For compatibility with MS
         compiler do not add @0 suffix here.  */
      if (TREE_VALUE (tree_last (formal_type)) != void_type_node)
        return DECL_ASSEMBLER_NAME (decl);

      /* Quit if we hit an incomplete type.  Error is reported
         by convert_arguments in c-typeck.c or cp/typeck.c.  */
      while (TREE_VALUE (formal_type) != void_type_node
	     && COMPLETE_TYPE_P (TREE_VALUE (formal_type)))
	{
	  int parm_size
	    = TREE_INT_CST_LOW (TYPE_SIZE (TREE_VALUE (formal_type)));
	    /* Must round up to include padding.  This is done the same
	       way as in store_one_arg.  */
	  parm_size = ((parm_size + PARM_BOUNDARY - 1)
		       / PARM_BOUNDARY * PARM_BOUNDARY);
	  total += parm_size;
	  formal_type = TREE_CHAIN (formal_type);\
	}
     }

  /* Assume max of 8 base 10 digits in the suffix.  */
  newsym = alloca (1 + strlen (asmname) + 1 + 8 + 1);
  p = newsym;
  if (fastcall)
    *p++ = FASTCALL_PREFIX;
  sprintf (p, "%s@%d", asmname, total/BITS_PER_UNIT);
  return get_identifier (newsym);
}

void
i386_pe_encode_section_info (tree decl, rtx rtl, int first)
{
  default_encode_section_info (decl, rtl, first);

  if (first && TREE_CODE (decl) == FUNCTION_DECL)
    {
      tree type_attributes = TYPE_ATTRIBUTES (TREE_TYPE (decl));
      tree newid = NULL_TREE;

      if (lookup_attribute ("stdcall", type_attributes))
	newid = gen_stdcall_or_fastcall_suffix (decl, false);
      else if (lookup_attribute ("fastcall", type_attributes))
	newid = gen_stdcall_or_fastcall_suffix (decl, true);
      if (newid != NULL_TREE)
	{
	  rtx rtlname = XEXP (rtl, 0);
	  if (GET_CODE (rtlname) == MEM)
	    rtlname = XEXP (rtlname, 0);
	  XSTR (rtlname, 0) = IDENTIFIER_POINTER (newid);
	  /* These attributes must be present on first declaration,
	     change_decl_assembler_name will warn if they are added
	     later and the decl has been referenced, but duplicate_decls
	     should catch the mismatch before this is called.  */
	  change_decl_assembler_name (decl, newid);
	}
    }

  /* Mark the decl so we can tell from the rtl whether the object is
     dllexport'd or dllimport'd.  tree.c: merge_dllimport_decl_attributes
     handles dllexport/dllimport override semantics.  */

  if (i386_pe_dllexport_p (decl))
    i386_pe_mark_dllexport (decl);
  else if (i386_pe_dllimport_p (decl))
    i386_pe_mark_dllimport (decl);
  /* It might be that DECL has been declared as dllimport, but a
     subsequent definition nullified that.  Assert that
     tree.c: merge_dllimport_decl_attributes has removed the attribute
     before the RTL name was marked with the DLL_IMPORT_PREFIX.  */
  else
    gcc_assert (!((TREE_CODE (decl) == FUNCTION_DECL
	    	   || TREE_CODE (decl) == VAR_DECL)
		  && rtl != NULL_RTX
		  && GET_CODE (rtl) == MEM
		  && GET_CODE (XEXP (rtl, 0)) == MEM
		  && GET_CODE (XEXP (XEXP (rtl, 0), 0)) == SYMBOL_REF
		  && i386_pe_dllimport_name_p (XSTR (XEXP (XEXP (rtl, 0), 0), 0))));
}

/* Strip only the leading encoding, leaving the stdcall suffix and fastcall
   prefix if it exists.  */

const char *
i386_pe_strip_name_encoding (const char *str)
{
  if (strncmp (str, DLL_IMPORT_PREFIX, strlen (DLL_IMPORT_PREFIX))
      == 0)
    str += strlen (DLL_IMPORT_PREFIX);
  else if (strncmp (str, DLL_EXPORT_PREFIX, strlen (DLL_EXPORT_PREFIX))
	   == 0)
    str += strlen (DLL_EXPORT_PREFIX);
  if (*str == '*')
    str += 1;
  return str;
}

/* Also strip the fastcall prefix and stdcall suffix.  */

const char *
i386_pe_strip_name_encoding_full (const char *str)
{
  const char *p;
  const char *name = i386_pe_strip_name_encoding (str);

  /* Strip leading '@' on fastcall symbols.  */
  if (*name == '@')
    name++;

  /* Strip trailing "@n".  */
  p = strchr (name, '@');
  if (p)
    return ggc_alloc_string (name, p - name);

  return name;
}

/* Output a reference to a label. Fastcall symbols are prefixed with @,
   whereas symbols for functions using other calling conventions don't
   have a prefix (unless they are marked dllimport or dllexport).  */

void i386_pe_output_labelref (FILE *stream, const char *name)
{
  if (strncmp (name, DLL_IMPORT_PREFIX, strlen (DLL_IMPORT_PREFIX))
      == 0)
    /* A dll import */
    {
      if (name[strlen (DLL_IMPORT_PREFIX)] == FASTCALL_PREFIX)
      /* A dllimport fastcall symbol.  */
        {
          fprintf (stream, "__imp_%s",
                   i386_pe_strip_name_encoding (name));
        }
      else
      /* A dllimport non-fastcall symbol.  */
        {
          fprintf (stream, "__imp__%s",
                   i386_pe_strip_name_encoding (name));
        }
    }
  else if ((name[0] == FASTCALL_PREFIX)
           || (strncmp (name, DLL_EXPORT_PREFIX, strlen (DLL_EXPORT_PREFIX))
	       == 0
	       && name[strlen (DLL_EXPORT_PREFIX)] == FASTCALL_PREFIX))
    /* A fastcall symbol.  */
    {
      fprintf (stream, "%s",
               i386_pe_strip_name_encoding (name));
    }
  else
    /* Everything else.  */
    {
      fprintf (stream, "%s%s", USER_LABEL_PREFIX,
               i386_pe_strip_name_encoding (name));
    }
}

void
i386_pe_unique_section (tree decl, int reloc)
{
  int len;
  const char *name, *prefix;
  char *string;

  name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
  name = i386_pe_strip_name_encoding_full (name);

  /* The object is put in, for example, section .text$foo.
     The linker will then ultimately place them in .text
     (everything from the $ on is stripped). Don't put
     read-only data in .rdata section to avoid a PE linker
     bug when .rdata$* grouped sections are used in code
     without a .rdata section.  */
  if (TREE_CODE (decl) == FUNCTION_DECL)
    prefix = ".text$";
  else if (decl_readonly_section (decl, reloc))
    prefix = ".rdata$";
  else
    prefix = ".data$";
  len = strlen (name) + strlen (prefix);
  string = alloca (len + 1);
  sprintf (string, "%s%s", prefix, name);

  DECL_SECTION_NAME (decl) = build_string (len, string);
}

/* Select a set of attributes for section NAME based on the properties
   of DECL and whether or not RELOC indicates that DECL's initializer
   might contain runtime relocations.

   We make the section read-only and executable for a function decl,
   read-only for a const data decl, and writable for a non-const data decl.

   If the section has already been defined, to not allow it to have
   different attributes, as (1) this is ambiguous since we're not seeing
   all the declarations up front and (2) some assemblers (e.g. SVR4)
   do not recognize section redefinitions.  */
/* ??? This differs from the "standard" PE implementation in that we
   handle the SHARED variable attribute.  Should this be done for all
   PE targets?  */

#define SECTION_PE_SHARED	SECTION_MACH_DEP

unsigned int
i386_pe_section_type_flags (tree decl, const char *name, int reloc)
{
  static htab_t htab;
  unsigned int flags;
  unsigned int **slot;

  /* The names we put in the hashtable will always be the unique
     versions given to us by the stringtable, so we can just use
     their addresses as the keys.  */
  if (!htab)
    htab = htab_create (31, htab_hash_pointer, htab_eq_pointer, NULL);

  if (decl && TREE_CODE (decl) == FUNCTION_DECL)
    flags = SECTION_CODE;
  else if (decl && decl_readonly_section (decl, reloc))
    flags = 0;
  else
    {
      flags = SECTION_WRITE;

      if (decl && TREE_CODE (decl) == VAR_DECL
	  && lookup_attribute ("shared", DECL_ATTRIBUTES (decl)))
	flags |= SECTION_PE_SHARED;
    }

  if (decl && DECL_ONE_ONLY (decl))
    flags |= SECTION_LINKONCE;

  /* See if we already have an entry for this section.  */
  slot = (unsigned int **) htab_find_slot (htab, name, INSERT);
  if (!*slot)
    {
      *slot = (unsigned int *) xmalloc (sizeof (unsigned int));
      **slot = flags;
    }
  else
    {
      if (decl && **slot != flags)
	error ("%q+D causes a section type conflict", decl);
    }

  return flags;
}

void
i386_pe_asm_named_section (const char *name, unsigned int flags,
			   tree decl)
{
  char flagchars[8], *f = flagchars;

  if ((flags & (SECTION_CODE | SECTION_WRITE)) == 0)
    /* readonly data */
    {
      *f++ ='d';  /* This is necessary for older versions of gas.  */
      *f++ ='r';
    }
  else
    {
      if (flags & SECTION_CODE)
        *f++ = 'x';
      if (flags & SECTION_WRITE)
        *f++ = 'w';
      if (flags & SECTION_PE_SHARED)
        *f++ = 's';
    }

  *f = '\0';

  fprintf (asm_out_file, "\t.section\t%s,\"%s\"\n", name, flagchars);

  if (flags & SECTION_LINKONCE)
    {
      /* Functions may have been compiled at various levels of
	 optimization so we can't use `same_size' here.
	 Instead, have the linker pick one, without warning.
	 If 'selectany' attribute has been specified,  MS compiler
	 sets 'discard' characteristic, rather than telling linker
	 to warn of size or content mismatch, so do the same.  */
      bool discard = (flags & SECTION_CODE)
		      || lookup_attribute ("selectany",
					   DECL_ATTRIBUTES (decl));
      fprintf (asm_out_file, "\t.linkonce %s\n",
	       (discard  ? "discard" : "same_size"));
    }
}

/* The Microsoft linker requires that every function be marked as
   DT_FCN.  When using gas on cygwin, we must emit appropriate .type
   directives.  */

#include "gsyms.h"

/* Mark a function appropriately.  This should only be called for
   functions for which we are not emitting COFF debugging information.
   FILE is the assembler output file, NAME is the name of the
   function, and PUBLIC is nonzero if the function is globally
   visible.  */

void
i386_pe_declare_function_type (FILE *file, const char *name, int public)
{
  fprintf (file, "\t.def\t");
  assemble_name (file, name);
  fprintf (file, ";\t.scl\t%d;\t.type\t%d;\t.endef\n",
	   public ? (int) C_EXT : (int) C_STAT,
	   (int) DT_FCN << N_BTSHFT);
}

/* Keep a list of external functions.  */

struct extern_list GTY(())
{
  struct extern_list *next;
  tree decl;
  const char *name;
};

static GTY(()) struct extern_list *extern_head;

/* Assemble an external function reference.  We need to keep a list of
   these, so that we can output the function types at the end of the
   assembly.  We can't output the types now, because we might see a
   definition of the function later on and emit debugging information
   for it then.  */

void
i386_pe_record_external_function (tree decl, const char *name)
{
  struct extern_list *p;

  p = (struct extern_list *) ggc_alloc (sizeof *p);
  p->next = extern_head;
  p->decl = decl;
  p->name = name;
  extern_head = p;
}

/* Keep a list of exported symbols.  */

struct export_list GTY(())
{
  struct export_list *next;
  const char *name;
  int is_data;		/* used to type tag exported symbols.  */
};

static GTY(()) struct export_list *export_head;

/* Assemble an export symbol entry.  We need to keep a list of
   these, so that we can output the export list at the end of the
   assembly.  We used to output these export symbols in each function,
   but that causes problems with GNU ld when the sections are
   linkonce.  */

void
i386_pe_record_exported_symbol (const char *name, int is_data)
{
  struct export_list *p;

  p = (struct export_list *) ggc_alloc (sizeof *p);
  p->next = export_head;
  p->name = name;
  p->is_data = is_data;
  export_head = p;
}

/* This is called at the end of assembly.  For each external function
   which has not been defined, we output a declaration now.  We also
   output the .drectve section.  */

void
i386_pe_file_end (void)
{
  struct extern_list *p;

  ix86_file_end ();

  for (p = extern_head; p != NULL; p = p->next)
    {
      tree decl;

      decl = p->decl;

      /* Positively ensure only one declaration for any given symbol.  */
      if (! TREE_ASM_WRITTEN (decl)
	  && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
	{
	  TREE_ASM_WRITTEN (decl) = 1;
	  i386_pe_declare_function_type (asm_out_file, p->name,
					 TREE_PUBLIC (decl));
	}
    }

  if (export_head)
    {
      struct export_list *q;
      drectve_section ();
      for (q = export_head; q != NULL; q = q->next)
	{
	  fprintf (asm_out_file, "\t.ascii \" -export:%s%s\"\n",
		   i386_pe_strip_name_encoding (q->name),
		   (q->is_data) ? ",data" : "");
	}
    }
}

#include "gt-winnt.h"