path: root/gcc/ada/gcc-interface/misc.c

/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                                 M I S C                                  *
 *                                                                          *
 *                           C Implementation File                          *
 *                                                                          *
 *          Copyright (C) 1992-2009, Free Software Foundation, Inc.         *
 *                                                                          *
 * GNAT is free software;  you can  redistribute it  and/or modify it under *
 * terms of the  GNU General Public License as published  by the Free Soft- *
 * ware  Foundation;  either version 2,  or (at your option) any later ver- *
 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
 * OUT 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  distributed with GNAT;  see file COPYING.  If not, write *
 * to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, *
 * Boston, MA 02110-1301, USA.                                              *
 *                                                                          *
 * As a  special  exception,  if you  link  this file  with other  files to *
 * produce an executable,  this file does not by itself cause the resulting *
 * executable to be covered by the GNU General Public License. This except- *
 * ion does not  however invalidate  any other reasons  why the  executable *
 * file might be covered by the  GNU Public License.                        *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

/* This file contains parts of the compiler that are required for interfacing
   with GCC but otherwise do nothing and parts of Gigi that need to know
   about RTL.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "real.h"
#include "rtl.h"
#include "diagnostic.h"
#include "expr.h"
#include "libfuncs.h"
#include "ggc.h"
#include "flags.h"
#include "debug.h"
#include "cgraph.h"
#include "tree-inline.h"
#include "insn-codes.h"
#include "insn-flags.h"
#include "insn-config.h"
#include "optabs.h"
#include "recog.h"
#include "toplev.h"
#include "output.h"
#include "except.h"
#include "tm_p.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "target.h"

#include "ada.h"
#include "types.h"
#include "atree.h"
#include "elists.h"
#include "namet.h"
#include "nlists.h"
#include "stringt.h"
#include "uintp.h"
#include "fe.h"
#include "sinfo.h"
#include "einfo.h"
#include "ada-tree.h"
#include "gigi.h"
#include "adadecode.h"
#include "opts.h"
#include "options.h"

extern FILE *asm_out_file;

/* The largest alignment, in bits, that is needed for using the widest
   move instruction.  */
unsigned int largest_move_alignment;

static bool gnat_init			(void);
static void gnat_finish_incomplete_decl	(tree);
static unsigned int gnat_init_options	(unsigned int, const char **);
static int gnat_handle_option		(size_t, const char *, int);
static bool gnat_post_options		(const char **);
static alias_set_type gnat_get_alias_set (tree);
static void gnat_print_decl		(FILE *, tree, int);
static void gnat_print_type		(FILE *, tree, int);
static const char *gnat_printable_name	(tree, int);
static const char *gnat_dwarf_name	(tree, int);
static tree gnat_return_tree		(tree);
static int gnat_eh_type_covers		(tree, tree);
static void gnat_parse_file		(int);
static rtx gnat_expand_expr		(tree, rtx, enum machine_mode, int,
					 rtx *);
static void internal_error_function	(const char *, va_list *);
static tree gnat_type_max_size		(const_tree);

/* Definitions for our language-specific hooks.  */

#undef  LANG_HOOKS_NAME
#define LANG_HOOKS_NAME			"GNU Ada"
#undef  LANG_HOOKS_IDENTIFIER_SIZE
#define LANG_HOOKS_IDENTIFIER_SIZE	sizeof (struct tree_identifier)
#undef  LANG_HOOKS_INIT
#define LANG_HOOKS_INIT			gnat_init
#undef  LANG_HOOKS_INIT_OPTIONS
#define LANG_HOOKS_INIT_OPTIONS		gnat_init_options
#undef  LANG_HOOKS_HANDLE_OPTION
#define LANG_HOOKS_HANDLE_OPTION	gnat_handle_option
#undef  LANG_HOOKS_POST_OPTIONS
#define LANG_HOOKS_POST_OPTIONS		gnat_post_options
#undef  LANG_HOOKS_PARSE_FILE
#define LANG_HOOKS_PARSE_FILE		gnat_parse_file
#undef  LANG_HOOKS_HASH_TYPES
#define LANG_HOOKS_HASH_TYPES		false
#undef  LANG_HOOKS_GETDECLS
#define LANG_HOOKS_GETDECLS		lhd_return_null_tree_v
#undef  LANG_HOOKS_PUSHDECL
#define LANG_HOOKS_PUSHDECL		gnat_return_tree
#undef  LANG_HOOKS_WRITE_GLOBALS
#define LANG_HOOKS_WRITE_GLOBALS	gnat_write_global_declarations
#undef  LANG_HOOKS_FINISH_INCOMPLETE_DECL
#define LANG_HOOKS_FINISH_INCOMPLETE_DECL gnat_finish_incomplete_decl
#undef  LANG_HOOKS_GET_ALIAS_SET
#define LANG_HOOKS_GET_ALIAS_SET	gnat_get_alias_set
#undef  LANG_HOOKS_EXPAND_EXPR
#define LANG_HOOKS_EXPAND_EXPR		gnat_expand_expr
#undef  LANG_HOOKS_MARK_ADDRESSABLE
#define LANG_HOOKS_MARK_ADDRESSABLE	gnat_mark_addressable
#undef  LANG_HOOKS_PRINT_DECL
#define LANG_HOOKS_PRINT_DECL		gnat_print_decl
#undef  LANG_HOOKS_PRINT_TYPE
#define LANG_HOOKS_PRINT_TYPE		gnat_print_type
#undef  LANG_HOOKS_TYPE_MAX_SIZE
#define LANG_HOOKS_TYPE_MAX_SIZE	gnat_type_max_size
#undef  LANG_HOOKS_DECL_PRINTABLE_NAME
#define LANG_HOOKS_DECL_PRINTABLE_NAME	gnat_printable_name
#undef  LANG_HOOKS_DWARF_NAME
#define LANG_HOOKS_DWARF_NAME		gnat_dwarf_name
#undef  LANG_HOOKS_GIMPLIFY_EXPR
#define LANG_HOOKS_GIMPLIFY_EXPR	gnat_gimplify_expr
#undef  LANG_HOOKS_TYPE_FOR_MODE
#define LANG_HOOKS_TYPE_FOR_MODE	gnat_type_for_mode
#undef  LANG_HOOKS_TYPE_FOR_SIZE
#define LANG_HOOKS_TYPE_FOR_SIZE	gnat_type_for_size
#undef  LANG_HOOKS_TYPES_COMPATIBLE_P
#define LANG_HOOKS_TYPES_COMPATIBLE_P	gnat_types_compatible_p
#undef  LANG_HOOKS_ATTRIBUTE_TABLE
#define LANG_HOOKS_ATTRIBUTE_TABLE	gnat_internal_attribute_table
#undef  LANG_HOOKS_BUILTIN_FUNCTION
#define LANG_HOOKS_BUILTIN_FUNCTION        gnat_builtin_function

const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;

/* How much we want of our DWARF extensions.  Some of our dwarf+ extensions
   are incompatible with regular GDB versions, so we must make sure to only
   produce them on explicit request.  This is eventually reflected into the
   use_gnu_debug_info_extensions common flag for later processing.  */

static int gnat_dwarf_extensions = 0;

/* Command-line argc and argv.
   These variables are global, since they are imported and used in
   back_end.adb  */

unsigned int save_argc;
const char **save_argv;

/* gnat standard argc argv */

extern int gnat_argc;
extern char **gnat_argv;


/* Declare functions we use as part of startup.  */
extern void __gnat_initialize           (void *);
extern void __gnat_install_SEH_handler  (void *);
extern void adainit		        (void);
extern void _ada_gnat1drv	        (void);

/* The parser for the language.  For us, we process the GNAT tree.  */

static void
gnat_parse_file (int set_yydebug ATTRIBUTE_UNUSED)
{
  int seh[2];

  /* Call the target specific initializations.  */
  __gnat_initialize (NULL);

  /* ??? Call the SEH initialization routine.  This is to workaround
  a bootstrap path problem.  The call below should be removed at some
  point and the SEH pointer passed to __gnat_initialize() above.  */
  __gnat_install_SEH_handler((void *)seh);

  /* Call the front-end elaboration procedures.  */
  adainit ();

  /* Call the front end.  */
  _ada_gnat1drv ();

  /* We always have a single compilation unit in Ada.  */
  cgraph_finalize_compilation_unit ();
}

/* Decode all the language specific options that cannot be decoded by GCC.
   The option decoding phase of GCC calls this routine on the flags that
   it cannot decode.  This routine returns the number of consecutive arguments
   from ARGV that it successfully decoded; 0 indicates failure.  */

static int
gnat_handle_option (size_t scode, const char *arg, int value)
{
  const struct cl_option *option = &cl_options[scode];
  enum opt_code code = (enum opt_code) scode;
  char *q;

  if (arg == NULL && (option->flags & (CL_JOINED | CL_SEPARATE)))
    {
      error ("missing argument to \"-%s\"", option->opt_text);
      return 1;
    }

  switch (code)
    {
    case OPT_I:
      q = XNEWVEC (char, sizeof("-I") + strlen (arg));
      strcpy (q, "-I");
      strcat (q, arg);
      gnat_argv[gnat_argc] = q;
      gnat_argc++;
      break;

    case OPT_Wall:
      warn_unused = value;

      /* We save the value of warn_uninitialized, since if they put
	 -Wuninitialized on the command line, we need to generate a
	 warning about not using it without also specifying -O.  */
      if (warn_uninitialized != 1)
	warn_uninitialized = (value ? 2 : 0);
      break;

      /* These are used in the GCC Makefile.  */
    case OPT_Wmissing_prototypes:
    case OPT_Wstrict_prototypes:
    case OPT_Wwrite_strings:
    case OPT_Wlong_long:
    case OPT_Wvariadic_macros:
    case OPT_Wold_style_definition:
    case OPT_Wmissing_format_attribute:
    case OPT_Woverlength_strings:
      break;

      /* This is handled by the front-end.  */
    case OPT_nostdinc:
      break;

    case OPT_nostdlib:
      gnat_argv[gnat_argc] = xstrdup ("-nostdlib");
      gnat_argc++;
      break;

    case OPT_feliminate_unused_debug_types:
      /* We arrange for post_option to be able to only set the corresponding
	 flag to 1 when explicitly requested by the user.  We expect the
	 default flag value to be either 0 or positive, and expose a positive
	 -f as a negative value to post_option.  */
      flag_eliminate_unused_debug_types = -value;
      break;

    case OPT_fRTS_:
      gnat_argv[gnat_argc] = xstrdup ("-fRTS");
      gnat_argc++;
      break;

    case OPT_gant:
      warning (0, "%<-gnat%> misspelled as %<-gant%>");

      /* ... fall through ... */

    case OPT_gnat:
      /* Recopy the switches without the 'gnat' prefix.  */
      gnat_argv[gnat_argc] = XNEWVEC (char, strlen (arg) + 2);
      gnat_argv[gnat_argc][0] = '-';
      strcpy (gnat_argv[gnat_argc] + 1, arg);
      gnat_argc++;
      break;

    case OPT_gnatO:
      gnat_argv[gnat_argc] = xstrdup ("-O");
      gnat_argc++;
      gnat_argv[gnat_argc] = xstrdup (arg);
      gnat_argc++;
      break;

    case OPT_gdwarf_:
      gnat_dwarf_extensions ++;
      break;

    default:
      gcc_unreachable ();
    }

  return 1;
}

/* Initialize for option processing.  */

static unsigned int
gnat_init_options (unsigned int argc, const char **argv)
{
  /* Initialize gnat_argv with save_argv size.  */
  gnat_argv = (char **) xmalloc ((argc + 1) * sizeof (argv[0]));
  gnat_argv[0] = xstrdup (argv[0]);     /* name of the command */
  gnat_argc = 1;

  save_argc = argc;
  save_argv = argv;

  /* Uninitialized really means uninitialized in Ada.  */
  flag_zero_initialized_in_bss = 0;

  return CL_Ada;
}

/* Post-switch processing.  */

bool
gnat_post_options (const char **pfilename ATTRIBUTE_UNUSED)
{
  /* ??? The warning machinery is outsmarted by Ada.  */
  warn_unused_parameter = 0;

  /* No psABI change warnings for Ada.  */
  warn_psabi = 0;

  /* Force eliminate_unused_debug_types to 0 unless an explicit positive
     -f has been passed.  This forces the default to 0 for Ada, which might
     differ from the common default.  */
  if (flag_eliminate_unused_debug_types < 0)
    flag_eliminate_unused_debug_types = 1;
  else
    flag_eliminate_unused_debug_types = 0;

  /* Reflect the explicit request of DWARF extensions into the common
     flag for use by later passes.  */
  if (write_symbols == DWARF2_DEBUG)
    use_gnu_debug_info_extensions = gnat_dwarf_extensions > 0;

  return false;
}

/* Here is the function to handle the compiler error processing in GCC.  */

static void
internal_error_function (const char *msgid, va_list *ap)
{
  text_info tinfo;
  char *buffer, *p, *loc;
  String_Template temp, temp_loc;
  Fat_Pointer fp, fp_loc;
  expanded_location s;

  /* Reset the pretty-printer.  */
  pp_clear_output_area (global_dc->printer);

  /* Format the message into the pretty-printer.  */
  tinfo.format_spec = msgid;
  tinfo.args_ptr = ap;
  tinfo.err_no = errno;
  pp_format_verbatim (global_dc->printer, &tinfo);

  /* Extract a (writable) pointer to the formatted text.  */
  buffer = (char*) pp_formatted_text (global_dc->printer);

  /* Go up to the first newline.  */
  for (p = buffer; *p; p++)
    if (*p == '\n')
      {
	*p = '\0';
	break;
      }

  temp.Low_Bound = 1;
  temp.High_Bound = p - buffer;
  fp.Bounds = &temp;
  fp.Array = buffer;

  s = expand_location (input_location);
  if (flag_show_column && s.column != 0)
    asprintf (&loc, "%s:%d:%d", s.file, s.line, s.column);
  else
    asprintf (&loc, "%s:%d", s.file, s.line);
  temp_loc.Low_Bound = 1;
  temp_loc.High_Bound = strlen (loc);
  fp_loc.Bounds = &temp_loc;
  fp_loc.Array = loc;

  Current_Error_Node = error_gnat_node;
  Compiler_Abort (fp, -1, fp_loc);
}

/* Perform all the initialization steps that are language-specific.  */

static bool
gnat_init (void)
{
  /* Performs whatever initialization steps needed by the language-dependent
     lexical analyzer.  */
  gnat_init_decl_processing ();

  /* Add the input filename as the last argument.  */
  gnat_argv[gnat_argc] = (char *) main_input_filename;
  gnat_argc++;
  gnat_argv[gnat_argc] = 0;

  global_dc->internal_error = &internal_error_function;

  /* Show that REFERENCE_TYPEs are internal and should be Pmode.  */
  internal_reference_types ();

  return true;
}

/* This function is called indirectly from toplev.c to handle incomplete
   declarations, i.e. VAR_DECL nodes whose DECL_SIZE is zero.  To be precise,
   compile_file in toplev.c makes an indirect call through the function pointer
   incomplete_decl_finalize_hook which is initialized to this routine in
   init_decl_processing.  */

static void
gnat_finish_incomplete_decl (tree dont_care ATTRIBUTE_UNUSED)
{
  gcc_unreachable ();
}

/* Compute the alignment of the largest mode that can be used for copying
   objects.  */

void
gnat_compute_largest_alignment (void)
{
  enum machine_mode mode;

  for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
       mode = GET_MODE_WIDER_MODE (mode))
    if (optab_handler (mov_optab, mode)->insn_code != CODE_FOR_nothing)
      largest_move_alignment = MIN (BIGGEST_ALIGNMENT,
				    MAX (largest_move_alignment,
					 GET_MODE_ALIGNMENT (mode)));
}

/* If we are using the GCC mechanism to process exception handling, we
   have to register the personality routine for Ada and to initialize
   various language dependent hooks.  */

void
gnat_init_gcc_eh (void)
{
#ifdef DWARF2_UNWIND_INFO
  /* lang_dependent_init already called dwarf2out_frame_init if true.  */
  int dwarf2out_frame_initialized = dwarf2out_do_frame ();
#endif

  /* We shouldn't do anything if the No_Exceptions_Handler pragma is set,
     though. This could for instance lead to the emission of tables with
     references to symbols (such as the Ada eh personality routine) within
     libraries we won't link against.  */
  if (No_Exception_Handlers_Set ())
    return;

  /* Tell GCC we are handling cleanup actions through exception propagation.
     This opens possibilities that we don't take advantage of yet, but is
     nonetheless necessary to ensure that fixup code gets assigned to the
     right exception regions.  */
  using_eh_for_cleanups ();

  eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
					     ? "__gnat_eh_personality_sj"
					     : "__gnat_eh_personality");
  lang_eh_type_covers = gnat_eh_type_covers;
  lang_eh_runtime_type = gnat_return_tree;
  default_init_unwind_resume_libfunc ();

  /* Turn on -fexceptions and -fnon-call-exceptions. The first one triggers
     the generation of the necessary exception runtime tables. The second one
     is useful for two reasons: 1/ we map some asynchronous signals like SEGV
     to exceptions, so we need to ensure that the insns which can lead to such
     signals are correctly attached to the exception region they pertain to,
     2/ Some calls to pure subprograms are handled as libcall blocks and then
     marked as "cannot trap" if the flag is not set (see emit_libcall_block).
     We should not let this be since it is possible for such calls to actually
     raise in Ada.  */
  flag_exceptions = 1;
  flag_non_call_exceptions = 1;

  init_eh ();
#ifdef DWARF2_UNWIND_INFO
  if (!dwarf2out_frame_initialized && dwarf2out_do_frame ())
    dwarf2out_frame_init ();
#endif
}

/* Language hooks, first one to print language-specific items in a DECL.  */

static void
gnat_print_decl (FILE *file, tree node, int indent)
{
  switch (TREE_CODE (node))
    {
    case CONST_DECL:
      print_node (file, "const_corresponding_var",
		  DECL_CONST_CORRESPONDING_VAR (node), indent + 4);
      break;

    case FIELD_DECL:
      print_node (file, "original_field", DECL_ORIGINAL_FIELD (node),
		  indent + 4);
      break;

    case VAR_DECL:
      print_node (file, "renamed_object", DECL_RENAMED_OBJECT (node),
		  indent + 4);
      break;

    default:
      break;
    }
}

static void
gnat_print_type (FILE *file, tree node, int indent)
{
  switch (TREE_CODE (node))
    {
    case FUNCTION_TYPE:
      print_node (file, "ci_co_list", TYPE_CI_CO_LIST (node), indent + 4);
      break;

    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
      print_node (file, "RM size", TYPE_RM_SIZE_NUM (node), indent + 4);
      break;

    case INTEGER_TYPE:
      if (TYPE_MODULAR_P (node))
	print_node (file, "modulus", TYPE_MODULUS (node), indent + 4);
      else if (TYPE_HAS_ACTUAL_BOUNDS_P (node))
	print_node (file, "actual bounds", TYPE_ACTUAL_BOUNDS (node),
		    indent + 4);
      else if (TYPE_VAX_FLOATING_POINT_P (node))
	;
      else
	print_node (file, "index type", TYPE_INDEX_TYPE (node), indent + 4);

      print_node (file, "RM size", TYPE_RM_SIZE_NUM (node), indent + 4);
      break;

    case ARRAY_TYPE:
      print_node (file,"actual bounds", TYPE_ACTUAL_BOUNDS (node), indent + 4);
      break;

    case RECORD_TYPE:
      if (TYPE_IS_FAT_POINTER_P (node) || TYPE_CONTAINS_TEMPLATE_P (node))
	print_node (file, "unconstrained array",
		    TYPE_UNCONSTRAINED_ARRAY (node), indent + 4);
      else
	print_node (file, "Ada size", TYPE_ADA_SIZE (node), indent + 4);
      break;

    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      print_node (file, "Ada size", TYPE_ADA_SIZE (node), indent + 4);
      break;

    default:
      break;
    }
}

static const char *
gnat_dwarf_name (tree t, int verbosity ATTRIBUTE_UNUSED)
{
  gcc_assert (DECL_P (t));

  return (const char *) IDENTIFIER_POINTER (DECL_NAME (t));
}

static const char *
gnat_printable_name (tree decl, int verbosity)
{
  const char *coded_name = IDENTIFIER_POINTER (DECL_NAME (decl));
  char *ada_name = (char *) ggc_alloc (strlen (coded_name) * 2 + 60);

  __gnat_decode (coded_name, ada_name, 0);

  if (verbosity == 2)
    {
      Set_Identifier_Casing (ada_name, (char *) DECL_SOURCE_FILE (decl));
      return ggc_strdup (Name_Buffer);
    }
  else
    return ada_name;
}

/* Expands GNAT-specific GCC tree nodes.  The only ones we support
   here are  and NULL_EXPR.  */

static rtx
gnat_expand_expr (tree exp, rtx target, enum machine_mode tmode,
		  int modifier, rtx *alt_rtl)
{
  tree type = TREE_TYPE (exp);
  tree new;

  /* Update EXP to be the new expression to expand.  */
  switch (TREE_CODE (exp))
    {
#if 0
    case ALLOCATE_EXPR:
      return
	allocate_dynamic_stack_space
	  (expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, TYPE_MODE (sizetype),
			EXPAND_NORMAL),
	   NULL_RTX, tree_low_cst (TREE_OPERAND (exp, 1), 1));
#endif

    case UNCONSTRAINED_ARRAY_REF:
      /* If we are evaluating just for side-effects, just evaluate our
	 operand.  Otherwise, abort since this code should never appear
	 in a tree to be evaluated (objects aren't unconstrained).  */
      if (target == const0_rtx || TREE_CODE (type) == VOID_TYPE)
	return expand_expr (TREE_OPERAND (exp, 0), const0_rtx,
			    VOIDmode, modifier);

      /* ... fall through ... */

    default:
      gcc_unreachable ();
    }

  return expand_expr_real (new, target, tmode, modifier, alt_rtl);
}

/* Do nothing (return the tree node passed).  */

static tree
gnat_return_tree (tree t)
{
  return t;
}

/* Return true if type A catches type B. Callback for flow analysis from
   the exception handling part of the back-end.  */

static int
gnat_eh_type_covers (tree a, tree b)
{
  /* a catches b if they represent the same exception id or if a
     is an "others".

     ??? integer_zero_node for "others" is hardwired in too many places
     currently.  */
  return (a == b || a == integer_zero_node);
}

/* Get the alias set corresponding to a type or expression.  */

static alias_set_type
gnat_get_alias_set (tree type)
{
  /* If this is a padding type, use the type of the first field.  */
  if (TREE_CODE (type) == RECORD_TYPE
      && TYPE_IS_PADDING_P (type))
    return get_alias_set (TREE_TYPE (TYPE_FIELDS (type)));

  /* If the type is an unconstrained array, use the type of the
     self-referential array we make.  */
  else if (TREE_CODE (type) == UNCONSTRAINED_ARRAY_TYPE)
    return
      get_alias_set (TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (type)))));

  /* If the type can alias any other types, return the alias set 0.  */
  else if (TYPE_P (type)
	   && TYPE_UNIVERSAL_ALIASING_P (TYPE_MAIN_VARIANT (type)))
    return 0;

  return -1;
}

/* GNU_TYPE is a type.  Return its maximum size in bytes, if known,
   as a constant when possible.  */

static tree
gnat_type_max_size (const_tree gnu_type)
{
  /* First see what we can get from TYPE_SIZE_UNIT, which might not
     be constant even for simple expressions if it has already been
     elaborated and possibly replaced by a VAR_DECL.  */
  tree max_unitsize = max_size (TYPE_SIZE_UNIT (gnu_type), true);

  /* If we don't have a constant, see what we can get from TYPE_ADA_SIZE,
     which should stay untouched.  */
  if (!host_integerp (max_unitsize, 1)
      && (TREE_CODE (gnu_type) == RECORD_TYPE
	  || TREE_CODE (gnu_type) == UNION_TYPE
	  || TREE_CODE (gnu_type) == QUAL_UNION_TYPE)
      && TYPE_ADA_SIZE (gnu_type))
    {
      tree max_adasize = max_size (TYPE_ADA_SIZE (gnu_type), true);

      /* If we have succeeded in finding a constant, round it up to the
	 type's alignment and return the result in units.  */
      if (host_integerp (max_adasize, 1))
	max_unitsize
	  = size_binop (CEIL_DIV_EXPR,
			round_up (max_adasize, TYPE_ALIGN (gnu_type)),
			bitsize_unit_node);
    }

  return max_unitsize;
}

/* GNU_TYPE is a type. Determine if it should be passed by reference by
   default.  */

bool
default_pass_by_ref (tree gnu_type)
{
  /* We pass aggregates by reference if they are sufficiently large.  The
     choice of constant here is somewhat arbitrary.  We also pass by
     reference if the target machine would either pass or return by
     reference.  Strictly speaking, we need only check the return if this
     is an In Out parameter, but it's probably best to err on the side of
     passing more things by reference.  */

  if (pass_by_reference (NULL, TYPE_MODE (gnu_type), gnu_type, 1))
    return true;

  if (targetm.calls.return_in_memory (gnu_type, NULL_TREE))
    return true;

  if (AGGREGATE_TYPE_P (gnu_type)
      && (!host_integerp (TYPE_SIZE (gnu_type), 1)
	  || 0 < compare_tree_int (TYPE_SIZE (gnu_type),
				   8 * TYPE_ALIGN (gnu_type))))
    return true;

  return false;
}

/* GNU_TYPE is the type of a subprogram parameter.  Determine from the type if
   it should be passed by reference. */

bool
must_pass_by_ref (tree gnu_type)
{
  /* We pass only unconstrained objects, those required by the language
     to be passed by reference, and objects of variable size.  The latter
     is more efficient, avoids problems with variable size temporaries,
     and does not produce compatibility problems with C, since C does
     not have such objects.  */
  return (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE
	  || (AGGREGATE_TYPE_P (gnu_type) && TYPE_BY_REFERENCE_P (gnu_type))
	  || (TYPE_SIZE (gnu_type)
	      && TREE_CODE (TYPE_SIZE (gnu_type)) != INTEGER_CST));
}

/* This function is called by the front end to enumerate all the supported
   modes for the machine.  We pass a function which is called back with
   the following integer parameters:

   FLOAT_P	nonzero if this represents a floating-point mode
   COMPLEX_P	nonzero is this represents a complex mode
   COUNT	count of number of items, nonzero for vector mode
   PRECISION	number of bits in data representation
   MANTISSA	number of bits in mantissa, if FP and known, else zero.
   SIZE		number of bits used to store data
   ALIGN	number of bits to which mode is aligned.  */

void
enumerate_modes (void (*f) (int, int, int, int, int, int, unsigned int))
{
  enum machine_mode i;

  for (i = 0; i < NUM_MACHINE_MODES; i++)
    {
      enum machine_mode j;
      bool float_p = 0;
      bool complex_p = 0;
      bool vector_p = 0;
      bool skip_p = 0;
      int mantissa = 0;
      enum machine_mode inner_mode = i;

      switch (GET_MODE_CLASS (i))
	{
	case MODE_INT:
	  break;
	case MODE_FLOAT:
	  float_p = 1;
	  break;
	case MODE_COMPLEX_INT:
	  complex_p = 1;
	  inner_mode = GET_MODE_INNER (i);
	  break;
	case MODE_COMPLEX_FLOAT:
	  float_p = 1;
	  complex_p = 1;
	  inner_mode = GET_MODE_INNER (i);
	  break;
	case MODE_VECTOR_INT:
	  vector_p = 1;
	  inner_mode = GET_MODE_INNER (i);
	  break;
	case MODE_VECTOR_FLOAT:
	  float_p = 1;
	  vector_p = 1;
	  inner_mode = GET_MODE_INNER (i);
	  break;
	default:
	  skip_p = 1;
	}

      /* Skip this mode if it's one the front end doesn't need to know about
	 (e.g., the CC modes) or if there is no add insn for that mode (or
	 any wider mode), meaning it is not supported by the hardware.  If
	 this a complex or vector mode, we care about the inner mode.  */
      for (j = inner_mode; j != VOIDmode; j = GET_MODE_WIDER_MODE (j))
	if (optab_handler (add_optab, j)->insn_code != CODE_FOR_nothing)
	  break;

      if (float_p)
	{
	  const struct real_format *fmt = REAL_MODE_FORMAT (inner_mode);

	  mantissa = fmt->p;
	}

      if (!skip_p && j != VOIDmode)
	(*f) (float_p, complex_p, vector_p ? GET_MODE_NUNITS (i) : 0,
	      GET_MODE_BITSIZE (i), mantissa,
	      GET_MODE_SIZE (i) * BITS_PER_UNIT, GET_MODE_ALIGNMENT (i));
    }
}

int
fp_prec_to_size (int prec)
{
  enum machine_mode mode;

  for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT); mode != VOIDmode;
       mode = GET_MODE_WIDER_MODE (mode))
    if (GET_MODE_PRECISION (mode) == prec)
      return GET_MODE_BITSIZE (mode);

  gcc_unreachable ();
}

int
fp_size_to_prec (int size)
{
  enum machine_mode mode;

  for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT); mode != VOIDmode;
       mode = GET_MODE_WIDER_MODE (mode))
    if (GET_MODE_BITSIZE (mode) == size)
      return GET_MODE_PRECISION (mode);

  gcc_unreachable ();
}