[gcc.git] / gcc / ada / gcc-interface / decl.c

/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                                 D E C L                                  *
 *                                                                          *
 *                          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 3,  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 along with GCC; see the file COPYING3.  If not see        *
 * <http://www.gnu.org/licenses/>.                                          *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
#include "toplev.h"
#include "convert.h"
#include "ggc.h"
#include "obstack.h"
#include "target.h"
#include "expr.h"

#include "ada.h"
#include "types.h"
#include "atree.h"
#include "elists.h"
#include "namet.h"
#include "nlists.h"
#include "repinfo.h"
#include "snames.h"
#include "stringt.h"
#include "uintp.h"
#include "fe.h"
#include "sinfo.h"
#include "einfo.h"
#include "hashtab.h"
#include "ada-tree.h"
#include "gigi.h"

#ifndef MAX_FIXED_MODE_SIZE
#define MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)
#endif

/* Convention_Stdcall should be processed in a specific way on Windows targets
   only.  The macro below is a helper to avoid having to check for a Windows
   specific attribute throughout this unit.  */

#if TARGET_DLLIMPORT_DECL_ATTRIBUTES
#define Has_Stdcall_Convention(E) (Convention (E) == Convention_Stdcall)
#else
#define Has_Stdcall_Convention(E) (0)
#endif

/* Stack realignment for functions with foreign conventions is provided on a
   per back-end basis now, as it is handled by the prologue expanders and not
   as part of the function's body any more.  It might be requested by way of a
   dedicated function type attribute on the targets that support it.

   We need a way to avoid setting the attribute on the targets that don't
   support it and use FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN for this purpose.

   It is defined on targets where the circuitry is available, and indicates
   whether the realignment is needed for 'main'.  We use this to decide for
   foreign subprograms as well.

   It is not defined on targets where the circuitry is not implemented, and
   we just never set the attribute in these cases.

   Whether it is defined on all targets that would need it in theory is
   not entirely clear.  We currently trust the base GCC settings for this
   purpose.  */

#ifndef FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
#define FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN 0
#endif

struct incomplete
{
  struct incomplete *next;
  tree old_type;
  Entity_Id full_type;
};

/* These variables are used to defer recursively expanding incomplete types
   while we are processing an array, a record or a subprogram type.  */
static int defer_incomplete_level = 0;
static struct incomplete *defer_incomplete_list;

/* This variable is used to delay expanding From_With_Type types until the
   end of the spec.  */
static struct incomplete *defer_limited_with;

/* These variables are used to defer finalizing types.  The element of the
   list is the TYPE_DECL associated with the type.  */
static int defer_finalize_level = 0;
static VEC (tree,heap) *defer_finalize_list;

/* A hash table used to cache the result of annotate_value.  */
static GTY ((if_marked ("tree_int_map_marked_p"),
             param_is (struct tree_int_map))) htab_t annotate_value_cache;

enum alias_set_op
{
  ALIAS_SET_COPY,
  ALIAS_SET_SUBSET,
  ALIAS_SET_SUPERSET
};

static void relate_alias_sets (tree, tree, enum alias_set_op);

static tree substitution_list (Entity_Id, Entity_Id, tree, bool);
static bool allocatable_size_p (tree, bool);
static void prepend_one_attribute_to (struct attrib **,
                                      enum attr_type, tree, tree, Node_Id);
static void prepend_attributes (Entity_Id, struct attrib **);
static tree elaborate_expression (Node_Id, Entity_Id, tree, bool, bool, bool);
static bool is_variable_size (tree);
static tree elaborate_expression_1 (Node_Id, Entity_Id, tree, tree,
                                    bool, bool);
static tree make_packable_type (tree, bool);
static tree gnat_to_gnu_field (Entity_Id, tree, int, bool);
static tree gnat_to_gnu_param (Entity_Id, Mechanism_Type, Entity_Id, bool,
                               bool *);
static bool same_discriminant_p (Entity_Id, Entity_Id);
static bool array_type_has_nonaliased_component (Entity_Id, tree);
static bool compile_time_known_address_p (Node_Id);
static void components_to_record (tree, Node_Id, tree, int, bool, tree *,
                                  bool, bool, bool, bool);
static Uint annotate_value (tree);
static void annotate_rep (Entity_Id, tree);
static tree compute_field_positions (tree, tree, tree, tree, unsigned int);
static tree validate_size (Uint, tree, Entity_Id, enum tree_code, bool, bool);
static void set_rm_size (Uint, tree, Entity_Id);
static tree make_type_from_size (tree, tree, bool);
static unsigned int validate_alignment (Uint, Entity_Id, unsigned int);
static unsigned int ceil_alignment (unsigned HOST_WIDE_INT);
static void check_ok_for_atomic (tree, Entity_Id, bool);
static int compatible_signatures_p (tree ftype1, tree ftype2);
static void rest_of_type_decl_compilation_no_defer (tree);
\f
/* Given GNAT_ENTITY, a GNAT defining identifier node, which denotes some Ada
   entity, return the equivalent GCC tree for that entity (a ..._DECL node)
   and associate the ..._DECL node with the input GNAT defining identifier.

   If GNAT_ENTITY is a variable or a constant declaration, GNU_EXPR gives its
   initial value (in GCC tree form).  This is optional for a variable.  For
   a renamed entity, GNU_EXPR gives the object being renamed.

   DEFINITION is nonzero if this call is intended for a definition.  This is
   used for separate compilation where it is necessary to know whether an
   external declaration or a definition must be created if the GCC equivalent
   was not created previously.  The value of 1 is normally used for a nonzero
   DEFINITION, but a value of 2 is used in special circumstances, defined in
   the code.  */

tree
gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
{
  Entity_Id gnat_equiv_type = Gigi_Equivalent_Type (gnat_entity);
  Entity_Id gnat_temp;
  Entity_Kind kind = Ekind (gnat_entity);
  /* Contains the GCC DECL node which is equivalent to the input GNAT node.
     This node will be associated with the GNAT node by calling at the end
     of the `switch' statement.  */
  tree gnu_decl = NULL_TREE;
  /* Contains the GCC type to be used for the GCC node.  */
  tree gnu_type = NULL_TREE;
  /* Contains the GCC size tree to be used for the GCC node.  */
  tree gnu_size = NULL_TREE;
  /* Contains the GCC name to be used for the GCC node.  */
  tree gnu_entity_id;
  /* True if we have already saved gnu_decl as a GNAT association.  */
  bool saved = false;
  /* True if we incremented defer_incomplete_level.  */
  bool this_deferred = false;
  /* True if we incremented force_global.  */
  bool this_global = false;
  /* True if we should check to see if elaborated during processing.  */
  bool maybe_present = false;
  /* True if we made GNU_DECL and its type here.  */
  bool this_made_decl = false;
  /* True if debug info is requested for this entity.  */
  bool debug_info_p = (Needs_Debug_Info (gnat_entity)
                       || debug_info_level == DINFO_LEVEL_VERBOSE);
  /* True if this entity is to be considered as imported.  */
  bool imported_p = (Is_Imported (gnat_entity)
                     && No (Address_Clause (gnat_entity)));
  unsigned int esize
    = ((Known_Esize (gnat_entity)
        && UI_Is_In_Int_Range (Esize (gnat_entity)))
       ? MIN (UI_To_Int (Esize (gnat_entity)),
              IN (kind, Float_Kind)
              ? fp_prec_to_size (LONG_DOUBLE_TYPE_SIZE)
              : IN (kind, Access_Kind) ? POINTER_SIZE * 2
              : LONG_LONG_TYPE_SIZE)
       : LONG_LONG_TYPE_SIZE);
  unsigned int align = 0;
  struct attrib *attr_list = NULL;

  /* Since a use of an Itype is a definition, process it as such if it
     is not in a with'ed unit.  */
  if (!definition
      && Is_Itype (gnat_entity)
      && !present_gnu_tree (gnat_entity)
      && In_Extended_Main_Code_Unit (gnat_entity))
    {
      /* Ensure that we are in a subprogram mentioned in the Scope chain of
         this entity, our current scope is global, or we encountered a task
         or entry (where we can't currently accurately check scoping).  */
      if (!current_function_decl
          || DECL_ELABORATION_PROC_P (current_function_decl))
        {
          process_type (gnat_entity);
          return get_gnu_tree (gnat_entity);
        }

      for (gnat_temp = Scope (gnat_entity);
           Present (gnat_temp);
           gnat_temp = Scope (gnat_temp))
        {
          if (Is_Type (gnat_temp))
            gnat_temp = Underlying_Type (gnat_temp);

          if (Ekind (gnat_temp) == E_Subprogram_Body)
            gnat_temp
              = Corresponding_Spec (Parent (Declaration_Node (gnat_temp)));

          if (IN (Ekind (gnat_temp), Subprogram_Kind)
              && Present (Protected_Body_Subprogram (gnat_temp)))
            gnat_temp = Protected_Body_Subprogram (gnat_temp);

          if (Ekind (gnat_temp) == E_Entry
              || Ekind (gnat_temp) == E_Entry_Family
              || Ekind (gnat_temp) == E_Task_Type
              || (IN (Ekind (gnat_temp), Subprogram_Kind)
                  && present_gnu_tree (gnat_temp)
                  && (current_function_decl
                      == gnat_to_gnu_entity (gnat_temp, NULL_TREE, 0))))
            {
              process_type (gnat_entity);
              return get_gnu_tree (gnat_entity);
            }
        }

      /* This abort means the entity has an incorrect scope, i.e. that its
         scope does not correspond to the subprogram it is declared in.  */
      gcc_unreachable ();
    }

  /* If the entiy is not present, something went badly wrong.  */
  gcc_assert (Present (gnat_entity));

  /* If we've already processed this entity, return what we got last time.
     If we are defining the node, we should not have already processed it.
     In that case, we will abort below when we try to save a new GCC tree
     for this object.  We also need to handle the case of getting a dummy
     type when a Full_View exists.  */
  if (present_gnu_tree (gnat_entity)
      && (!definition || (Is_Type (gnat_entity) && imported_p)))
    {
      gnu_decl = get_gnu_tree (gnat_entity);

      if (TREE_CODE (gnu_decl) == TYPE_DECL
          && TYPE_IS_DUMMY_P (TREE_TYPE (gnu_decl))
          && IN (kind, Incomplete_Or_Private_Kind)
          && Present (Full_View (gnat_entity)))
        {
          gnu_decl
            = gnat_to_gnu_entity (Full_View (gnat_entity), NULL_TREE, 0);
          save_gnu_tree (gnat_entity, NULL_TREE, false);
          save_gnu_tree (gnat_entity, gnu_decl, false);
        }

      return gnu_decl;
    }

  /* If this is a numeric or enumeral type, or an access type, a nonzero
     Esize must be specified unless it was specified by the programmer.  */
  gcc_assert (!Unknown_Esize (gnat_entity)
              || Has_Size_Clause (gnat_entity)
              || (!IN (kind, Numeric_Kind)
                  && !IN (kind, Enumeration_Kind)
                  && (!IN (kind, Access_Kind)
                      || kind == E_Access_Protected_Subprogram_Type
                      || kind == E_Anonymous_Access_Protected_Subprogram_Type
                      || kind == E_Access_Subtype)));

  /* RM_Size must be specified for all discrete and fixed-point types.  */
  gcc_assert (!IN (kind, Discrete_Or_Fixed_Point_Kind)
              || !Unknown_RM_Size (gnat_entity));

  /* Get the name of the entity and set up the line number and filename of
     the original definition for use in any decl we make.  */
  gnu_entity_id = get_entity_name (gnat_entity);
  Sloc_to_locus (Sloc (gnat_entity), &input_location);

  /* If we get here, it means we have not yet done anything with this
     entity.  If we are not defining it here, it must be external,
     otherwise we should have defined it already.  */
  gcc_assert (definition || Is_Public (gnat_entity) || type_annotate_only
              || kind == E_Discriminant || kind == E_Component
              || kind == E_Label
              || (kind == E_Constant && Present (Full_View (gnat_entity)))
              || IN (kind, Type_Kind));

  /* For cases when we are not defining (i.e., we are referencing from
     another compilation unit) public entities, show we are at global level
     for the purpose of computing scopes.  Don't do this for components or
     discriminants since the relevant test is whether or not the record is
     being defined.  But do this for Imported functions or procedures in
     all cases.  */
  if ((!definition && Is_Public (gnat_entity)
       && !Is_Statically_Allocated (gnat_entity)
       && kind != E_Discriminant && kind != E_Component)
      || (Is_Imported (gnat_entity)
          && (kind == E_Function || kind == E_Procedure)))
    force_global++, this_global = true;

  /* Handle any attributes directly attached to the entity.  */
  if (Has_Gigi_Rep_Item (gnat_entity))
    prepend_attributes (gnat_entity, &attr_list);

  /* Machine_Attributes on types are expected to be propagated to subtypes.
     The corresponding Gigi_Rep_Items are only attached to the first subtype
     though, so we handle the propagation here.  */
  if (Is_Type (gnat_entity) && Base_Type (gnat_entity) != gnat_entity
      && !Is_First_Subtype (gnat_entity)
      && Has_Gigi_Rep_Item (First_Subtype (Base_Type (gnat_entity))))
    prepend_attributes (First_Subtype (Base_Type (gnat_entity)), &attr_list);

  switch (kind)
    {
    case E_Constant:
      /* If this is a use of a deferred constant without address clause,
         get its full definition.  */
      if (!definition
          && No (Address_Clause (gnat_entity))
          && Present (Full_View (gnat_entity)))
        {
          gnu_decl
            = gnat_to_gnu_entity (Full_View (gnat_entity), gnu_expr, 0);
          saved = true;
          break;
        }

      /* If we have an external constant that we are not defining, get the
         expression that is was defined to represent.  We may throw that
         expression away later if it is not a constant.  Do not retrieve the
         expression if it is an aggregate or allocator, because in complex
         instantiation contexts it may not be expanded  */
      if (!definition
          && Present (Expression (Declaration_Node (gnat_entity)))
          && !No_Initialization (Declaration_Node (gnat_entity))
          && (Nkind (Expression (Declaration_Node (gnat_entity)))
              != N_Aggregate)
          && (Nkind (Expression (Declaration_Node (gnat_entity)))
              != N_Allocator))
        gnu_expr = gnat_to_gnu (Expression (Declaration_Node (gnat_entity)));

      /* Ignore deferred constant definitions without address clause since
         they are processed fully in the front-end.  If No_Initialization
         is set, this is not a deferred constant but a constant whose value
         is built manually.  And constants that are renamings are handled
         like variables.  */
      if (definition
          && !gnu_expr
          && No (Address_Clause (gnat_entity))
          && !No_Initialization (Declaration_Node (gnat_entity))
          && No (Renamed_Object (gnat_entity)))
        {
          gnu_decl = error_mark_node;
          saved = true;
          break;
        }

      /* Ignore constant definitions already marked with the error node.  See
         the N_Object_Declaration case of gnat_to_gnu for the rationale.  */
      if (definition
          && gnu_expr
          && present_gnu_tree (gnat_entity)
          && get_gnu_tree (gnat_entity) == error_mark_node)
        {
          maybe_present = true;
          break;
        }

      goto object;

    case E_Exception:
      /* We used to special case VMS exceptions here to directly map them to
         their associated condition code.  Since this code had to be masked
         dynamically to strip off the severity bits, this caused trouble in
         the GCC/ZCX case because the "type" pointers we store in the tables
         have to be static.  We now don't special case here anymore, and let
         the regular processing take place, which leaves us with a regular
         exception data object for VMS exceptions too.  The condition code
         mapping is taken care of by the front end and the bitmasking by the
         runtime library.  */
      goto object;

    case E_Discriminant:
    case E_Component:
      {
        /* The GNAT record where the component was defined.  */
        Entity_Id gnat_record = Underlying_Type (Scope (gnat_entity));

        /* If the variable is an inherited record component (in the case of
           extended record types), just return the inherited entity, which
           must be a FIELD_DECL.  Likewise for discriminants.
           For discriminants of untagged records which have explicit
           stored discriminants, return the entity for the corresponding
           stored discriminant.  Also use Original_Record_Component
           if the record has a private extension.  */
        if (Present (Original_Record_Component (gnat_entity))
            && Original_Record_Component (gnat_entity) != gnat_entity)
          {
            gnu_decl
              = gnat_to_gnu_entity (Original_Record_Component (gnat_entity),
                                    gnu_expr, definition);
            saved = true;
            break;
          }

        /* If the enclosing record has explicit stored discriminants,
           then it is an untagged record.  If the Corresponding_Discriminant
           is not empty then this must be a renamed discriminant and its
           Original_Record_Component must point to the corresponding explicit
           stored discriminant (i.e. we should have taken the previous
           branch).  */
        else if (Present (Corresponding_Discriminant (gnat_entity))
                 && Is_Tagged_Type (gnat_record))
          {
            /* A tagged record has no explicit stored discriminants.  */
            gcc_assert (First_Discriminant (gnat_record)
                       == First_Stored_Discriminant (gnat_record));
            gnu_decl
              = gnat_to_gnu_entity (Corresponding_Discriminant (gnat_entity),
                                    gnu_expr, definition);
            saved = true;
            break;
          }

        else if (Present (CR_Discriminant (gnat_entity))
                 && type_annotate_only)
          {
            gnu_decl = gnat_to_gnu_entity (CR_Discriminant (gnat_entity),
                                           gnu_expr, definition);
            saved = true;
            break;
          }

        /* If the enclosing record has explicit stored discriminants, then
           it is an untagged record.  If the Corresponding_Discriminant
           is not empty then this must be a renamed discriminant and its
           Original_Record_Component must point to the corresponding explicit
           stored discriminant (i.e. we should have taken the first
           branch).  */
        else if (Present (Corresponding_Discriminant (gnat_entity))
                 && (First_Discriminant (gnat_record)
                     != First_Stored_Discriminant (gnat_record)))
          gcc_unreachable ();

        /* Otherwise, if we are not defining this and we have no GCC type
           for the containing record, make one for it.  Then we should
           have made our own equivalent.  */
        else if (!definition && !present_gnu_tree (gnat_record))
          {
            /* ??? If this is in a record whose scope is a protected
               type and we have an Original_Record_Component, use it.
               This is a workaround for major problems in protected type
               handling.  */
            Entity_Id Scop = Scope (Scope (gnat_entity));
            if ((Is_Protected_Type (Scop)
                 || (Is_Private_Type (Scop)
                     && Present (Full_View (Scop))
                     && Is_Protected_Type (Full_View (Scop))))
                && Present (Original_Record_Component (gnat_entity)))
              {
                gnu_decl
                  = gnat_to_gnu_entity (Original_Record_Component
                                        (gnat_entity),
                                        gnu_expr, 0);
                saved = true;
                break;
              }

            gnat_to_gnu_entity (Scope (gnat_entity), NULL_TREE, 0);
            gnu_decl = get_gnu_tree (gnat_entity);
            saved = true;
            break;
          }

        else
          /* Here we have no GCC type and this is a reference rather than a
             definition.  This should never happen.  Most likely the cause is
             reference before declaration in the gnat tree for gnat_entity.  */
          gcc_unreachable ();
      }

    case E_Loop_Parameter:
    case E_Out_Parameter:
    case E_Variable:

      /* Simple variables, loop variables, Out parameters, and exceptions.  */
    object:
      {
        bool used_by_ref = false;
        bool const_flag
          = ((kind == E_Constant || kind == E_Variable)
             && Is_True_Constant (gnat_entity)
             && !Treat_As_Volatile (gnat_entity)
             && (((Nkind (Declaration_Node (gnat_entity))
                   == N_Object_Declaration)
                  && Present (Expression (Declaration_Node (gnat_entity))))
                 || Present (Renamed_Object (gnat_entity))));
        bool inner_const_flag = const_flag;
        bool static_p = Is_Statically_Allocated (gnat_entity);
        bool mutable_p = false;
        tree gnu_ext_name = NULL_TREE;
        tree renamed_obj = NULL_TREE;
        tree gnu_object_size;

        if (Present (Renamed_Object (gnat_entity)) && !definition)
          {
            if (kind == E_Exception)
              gnu_expr = gnat_to_gnu_entity (Renamed_Entity (gnat_entity),
                                             NULL_TREE, 0);
            else
              gnu_expr = gnat_to_gnu (Renamed_Object (gnat_entity));
          }

        /* Get the type after elaborating the renamed object.  */
        gnu_type = gnat_to_gnu_type (Etype (gnat_entity));

        /* For a debug renaming declaration, build a pure debug entity.  */
        if (Present (Debug_Renaming_Link (gnat_entity)))
          {
            rtx addr;
            gnu_decl = build_decl (VAR_DECL, gnu_entity_id, gnu_type);
            /* The (MEM (CONST (0))) pattern is prescribed by STABS.  */
            if (global_bindings_p ())
              addr = gen_rtx_CONST (VOIDmode, const0_rtx);
            else
              addr = stack_pointer_rtx;
            SET_DECL_RTL (gnu_decl, gen_rtx_MEM (Pmode, addr));
            gnat_pushdecl (gnu_decl, gnat_entity);
            break;
          }

        /* If this is a loop variable, its type should be the base type.
           This is because the code for processing a loop determines whether
           a normal loop end test can be done by comparing the bounds of the
           loop against those of the base type, which is presumed to be the
           size used for computation.  But this is not correct when the size
           of the subtype is smaller than the type.  */
        if (kind == E_Loop_Parameter)
          gnu_type = get_base_type (gnu_type);

        /* Reject non-renamed objects whose types are unconstrained arrays or
           any object whose type is a dummy type or VOID_TYPE.  */

        if ((TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE
             && No (Renamed_Object (gnat_entity)))
            || TYPE_IS_DUMMY_P (gnu_type)
            || TREE_CODE (gnu_type) == VOID_TYPE)
          {
            gcc_assert (type_annotate_only);
            if (this_global)
              force_global--;
            return error_mark_node;
          }

        /* If an alignment is specified, use it if valid.   Note that
           exceptions are objects but don't have alignments.  We must do this
           before we validate the size, since the alignment can affect the
           size.  */
        if (kind != E_Exception && Known_Alignment (gnat_entity))
          {
            gcc_assert (Present (Alignment (gnat_entity)));
            align = validate_alignment (Alignment (gnat_entity), gnat_entity,
                                        TYPE_ALIGN (gnu_type));
            gnu_type = maybe_pad_type (gnu_type, NULL_TREE, align, gnat_entity,
                                       "PAD", false, definition, true);
          }

        /* If we are defining the object, see if it has a Size value and
           validate it if so.  If we are not defining the object and a Size
           clause applies, simply retrieve the value.  We don't want to ignore
           the clause and it is expected to have been validated already.  Then
           get the new type, if any.  */
        if (definition)
          gnu_size = validate_size (Esize (gnat_entity), gnu_type,
                                    gnat_entity, VAR_DECL, false,
                                    Has_Size_Clause (gnat_entity));
        else if (Has_Size_Clause (gnat_entity))
          gnu_size = UI_To_gnu (Esize (gnat_entity), bitsizetype);

        if (gnu_size)
          {
            gnu_type
              = make_type_from_size (gnu_type, gnu_size,
                                     Has_Biased_Representation (gnat_entity));

            if (operand_equal_p (TYPE_SIZE (gnu_type), gnu_size, 0))
              gnu_size = NULL_TREE;
          }

        /* If this object has self-referential size, it must be a record with
           a default value.  We are supposed to allocate an object of the
           maximum size in this case unless it is a constant with an
           initializing expression, in which case we can get the size from
           that.  Note that the resulting size may still be a variable, so
           this may end up with an indirect allocation.  */
        if (No (Renamed_Object (gnat_entity))
            && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type)))
          {
            if (gnu_expr && kind == E_Constant)
              {
                tree size = TYPE_SIZE (TREE_TYPE (gnu_expr));
                if (CONTAINS_PLACEHOLDER_P (size))
                  {
                    /* If the initializing expression is itself a constant,
                       despite having a nominal type with self-referential
                       size, we can get the size directly from it.  */
                    if (TREE_CODE (gnu_expr) == COMPONENT_REF
                        && TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_expr, 0)))
                           == RECORD_TYPE
                        && TYPE_IS_PADDING_P
                           (TREE_TYPE (TREE_OPERAND (gnu_expr, 0)))
                        && TREE_CODE (TREE_OPERAND (gnu_expr, 0)) == VAR_DECL
                        && (TREE_READONLY (TREE_OPERAND (gnu_expr, 0))
                            || DECL_READONLY_ONCE_ELAB
                               (TREE_OPERAND (gnu_expr, 0))))
                      gnu_size = DECL_SIZE (TREE_OPERAND (gnu_expr, 0));
                    else
                      gnu_size
                        = SUBSTITUTE_PLACEHOLDER_IN_EXPR (size, gnu_expr);
                  }
                else
                  gnu_size = size;
              }
            /* We may have no GNU_EXPR because No_Initialization is
               set even though there's an Expression.  */
            else if (kind == E_Constant
                     && (Nkind (Declaration_Node (gnat_entity))
                         == N_Object_Declaration)
                     && Present (Expression (Declaration_Node (gnat_entity))))
              gnu_size
                = TYPE_SIZE (gnat_to_gnu_type
                             (Etype
                              (Expression (Declaration_Node (gnat_entity)))));
            else
              {
                gnu_size = max_size (TYPE_SIZE (gnu_type), true);
                mutable_p = true;
              }
          }

        /* If the size is zero bytes, make it one byte since some linkers have
           trouble with zero-sized objects.  If the object will have a
           template, that will make it nonzero so don't bother.  Also avoid
           doing that for an object renaming or an object with an address
           clause, as we would lose useful information on the view size
           (e.g. for null array slices) and we are not allocating the object
           here anyway.  */
        if (((gnu_size
              && integer_zerop (gnu_size)
              && !TREE_OVERFLOW (gnu_size))
             || (TYPE_SIZE (gnu_type)
                 && integer_zerop (TYPE_SIZE (gnu_type))
                 && !TREE_OVERFLOW (TYPE_SIZE (gnu_type))))
            && (!Is_Constr_Subt_For_UN_Aliased (Etype (gnat_entity))
                || !Is_Array_Type (Etype (gnat_entity)))
            && !Present (Renamed_Object (gnat_entity))
            && !Present (Address_Clause (gnat_entity)))
          gnu_size = bitsize_unit_node;

        /* If this is an object with no specified size and alignment, and
           if either it is atomic or we are not optimizing alignment for
           space and it is composite and not an exception, an Out parameter
           or a reference to another object, and the size of its type is a
           constant, set the alignment to the smallest one which is not
           smaller than the size, with an appropriate cap.  */
        if (!gnu_size && align == 0
            && (Is_Atomic (gnat_entity)
                || (!Optimize_Alignment_Space (gnat_entity)
                    && kind != E_Exception
                    && kind != E_Out_Parameter
                    && Is_Composite_Type (Etype (gnat_entity))
                    && !Is_Constr_Subt_For_UN_Aliased (Etype (gnat_entity))
                    && !imported_p
                    && No (Renamed_Object (gnat_entity))
                    && No (Address_Clause (gnat_entity))))
            && TREE_CODE (TYPE_SIZE (gnu_type)) == INTEGER_CST)
          {
            /* No point in jumping through all the hoops needed in order
               to support BIGGEST_ALIGNMENT if we don't really have to.
               So we cap to the smallest alignment that corresponds to
               a known efficient memory access pattern of the target.  */
            unsigned int align_cap = Is_Atomic (gnat_entity)
                                     ? BIGGEST_ALIGNMENT
                                     : get_mode_alignment (ptr_mode);

            if (!host_integerp (TYPE_SIZE (gnu_type), 1)
                || compare_tree_int (TYPE_SIZE (gnu_type), align_cap) >= 0)
              align = align_cap;
            else
              align = ceil_alignment (tree_low_cst (TYPE_SIZE (gnu_type), 1));

            /* But make sure not to under-align the object.  */
            if (align <= TYPE_ALIGN (gnu_type))
              align = 0;

            /* And honor the minimum valid atomic alignment, if any.  */
#ifdef MINIMUM_ATOMIC_ALIGNMENT
            else if (align < MINIMUM_ATOMIC_ALIGNMENT)
              align = MINIMUM_ATOMIC_ALIGNMENT;
#endif
          }

        /* If the object is set to have atomic components, find the component
           type and validate it.

           ??? Note that we ignore Has_Volatile_Components on objects; it's
           not at all clear what to do in that case.  */

        if (Has_Atomic_Components (gnat_entity))
          {
            tree gnu_inner = (TREE_CODE (gnu_type) == ARRAY_TYPE
                              ? TREE_TYPE (gnu_type) : gnu_type);

            while (TREE_CODE (gnu_inner) == ARRAY_TYPE
                   && TYPE_MULTI_ARRAY_P (gnu_inner))
              gnu_inner = TREE_TYPE (gnu_inner);

            check_ok_for_atomic (gnu_inner, gnat_entity, true);
          }

        /* Now check if the type of the object allows atomic access.  Note
           that we must test the type, even if this object has size and
           alignment to allow such access, because we will be going
           inside the padded record to assign to the object.  We could fix
           this by always copying via an intermediate value, but it's not
           clear it's worth the effort.  */
        if (Is_Atomic (gnat_entity))
          check_ok_for_atomic (gnu_type, gnat_entity, false);

        /* If this is an aliased object with an unconstrained nominal subtype,
           make a type that includes the template.  */
        if (Is_Constr_Subt_For_UN_Aliased (Etype (gnat_entity))
            && Is_Array_Type (Etype (gnat_entity))
            && !type_annotate_only)
        {
          tree gnu_fat
            = TREE_TYPE (gnat_to_gnu_type (Base_Type (Etype (gnat_entity))));

          gnu_type
            = build_unc_object_type_from_ptr (gnu_fat, gnu_type,
                                     concat_id_with_name (gnu_entity_id,
                                                          "UNC"));
        }

#ifdef MINIMUM_ATOMIC_ALIGNMENT
        /* If the size is a constant and no alignment is specified, force
           the alignment to be the minimum valid atomic alignment.  The
           restriction on constant size avoids problems with variable-size
           temporaries; if the size is variable, there's no issue with
           atomic access.  Also don't do this for a constant, since it isn't
           necessary and can interfere with constant replacement.  Finally,
           do not do it for Out parameters since that creates an
           size inconsistency with In parameters.  */
        if (align == 0 && MINIMUM_ATOMIC_ALIGNMENT > TYPE_ALIGN (gnu_type)
            && !FLOAT_TYPE_P (gnu_type)
            && !const_flag && No (Renamed_Object (gnat_entity))
            && !imported_p && No (Address_Clause (gnat_entity))
            && kind != E_Out_Parameter
            && (gnu_size ? TREE_CODE (gnu_size) == INTEGER_CST
                : TREE_CODE (TYPE_SIZE (gnu_type)) == INTEGER_CST))
          align = MINIMUM_ATOMIC_ALIGNMENT;
#endif

        /* Make a new type with the desired size and alignment, if needed.
           But do not take into account alignment promotions to compute the
           size of the object.  */
        gnu_object_size = gnu_size ? gnu_size : TYPE_SIZE (gnu_type);
        if (gnu_size || align > 0)
          gnu_type = maybe_pad_type (gnu_type, gnu_size, align, gnat_entity,
                                     "PAD", false, definition,
                                     gnu_size ? true : false);

        /* If this is a renaming, avoid as much as possible to create a new
           object.  However, in several cases, creating it is required.
           This processing needs to be applied to the raw expression so
           as to make it more likely to rename the underlying object.  */
        if (Present (Renamed_Object (gnat_entity)))
          {
            bool create_normal_object = false;

            /* If the renamed object had padding, strip off the reference
               to the inner object and reset our type.  */
            if ((TREE_CODE (gnu_expr) == COMPONENT_REF
                 && TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_expr, 0)))
                    == RECORD_TYPE
                 && TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_expr, 0))))
                /* Strip useless conversions around the object.  */
                || (TREE_CODE (gnu_expr) == NOP_EXPR
                    && gnat_types_compatible_p
                       (TREE_TYPE (gnu_expr),
                        TREE_TYPE (TREE_OPERAND (gnu_expr, 0)))))
              {
                gnu_expr = TREE_OPERAND (gnu_expr, 0);
                gnu_type = TREE_TYPE (gnu_expr);
              }

            /* Case 1: If this is a constant renaming stemming from a function
               call, treat it as a normal object whose initial value is what
               is being renamed.  RM 3.3 says that the result of evaluating a
               function call is a constant object.  As a consequence, it can
               be the inner object of a constant renaming.  In this case, the
               renaming must be fully instantiated, i.e. it cannot be a mere
               reference to (part of) an existing object.  */
            if (const_flag)
              {
                tree inner_object = gnu_expr;
                while (handled_component_p (inner_object))
                  inner_object = TREE_OPERAND (inner_object, 0);
                if (TREE_CODE (inner_object) == CALL_EXPR)
                  create_normal_object = true;
              }

            /* Otherwise, see if we can proceed with a stabilized version of
               the renamed entity or if we need to make a new object.  */
            if (!create_normal_object)
              {
                tree maybe_stable_expr = NULL_TREE;
                bool stable = false;

                /* Case 2: If the renaming entity need not be materialized and
                   the renamed expression is something we can stabilize, use
                   that for the renaming.  At the global level, we can only do
                   this if we know no SAVE_EXPRs need be made, because the
                   expression we return might be used in arbitrary conditional
                   branches so we must force the SAVE_EXPRs evaluation
                   immediately and this requires a function context.  */
                if (!Materialize_Entity (gnat_entity)
                    && (!global_bindings_p ()
                        || (staticp (gnu_expr)
                            && !TREE_SIDE_EFFECTS (gnu_expr))))
                  {
                    maybe_stable_expr
                      = maybe_stabilize_reference (gnu_expr, true, &stable);

                    if (stable)
                      {
                        gnu_decl = maybe_stable_expr;
                        /* ??? No DECL_EXPR is created so we need to mark
                           the expression manually lest it is shared.  */
                        if (global_bindings_p ())
                          mark_visited (&gnu_decl);
                        save_gnu_tree (gnat_entity, gnu_decl, true);
                        saved = true;
                        break;
                      }

                    /* The stabilization failed.  Keep maybe_stable_expr
                       untouched here to let the pointer case below know
                       about that failure.  */
                  }

                /* Case 3: If this is a constant renaming and creating a
                   new object is allowed and cheap, treat it as a normal
                   object whose initial value is what is being renamed.  */
                if (const_flag && Is_Elementary_Type (Etype (gnat_entity)))
                  ;

                /* Case 4: Make this into a constant pointer to the object we
                   are to rename and attach the object to the pointer if it is
                   something we can stabilize.

                   From the proper scope, attached objects will be referenced
                   directly instead of indirectly via the pointer to avoid
                   subtle aliasing problems with non-addressable entities.
                   They have to be stable because we must not evaluate the
                   variables in the expression every time the renaming is used.
                   The pointer is called a "renaming" pointer in this case.

                   In the rare cases where we cannot stabilize the renamed
                   object, we just make a "bare" pointer, and the renamed
                   entity is always accessed indirectly through it.  */
                else
                  {
                    gnu_type = build_reference_type (gnu_type);
                    inner_const_flag = TREE_READONLY (gnu_expr);
                    const_flag = true;

                    /* If the previous attempt at stabilizing failed, there
                       is no point in trying again and we reuse the result
                       without attaching it to the pointer.  In this case it
                       will only be used as the initializing expression of
                       the pointer and thus needs no special treatment with
                       regard to multiple evaluations.  */
                    if (maybe_stable_expr)
                      ;

                    /* Otherwise, try to stabilize and attach the expression
                       to the pointer if the stabilization succeeds.

                       Note that this might introduce SAVE_EXPRs and we don't
                       check whether we're at the global level or not.  This
                       is fine since we are building a pointer initializer and
                       neither the pointer nor the initializing expression can
                       be accessed before the pointer elaboration has taken
                       place in a correct program.

                       These SAVE_EXPRs will be evaluated at the right place
                       by either the evaluation of the initializer for the
                       non-global case or the elaboration code for the global
                       case, and will be attached to the elaboration procedure
                       in the latter case.  */
                    else
                     {
                        maybe_stable_expr
                          = maybe_stabilize_reference (gnu_expr, true, &stable);

                        if (stable)
                          renamed_obj = maybe_stable_expr;

                        /* Attaching is actually performed downstream, as soon
                           as we have a VAR_DECL for the pointer we make.  */
                      }

                    gnu_expr
                      = build_unary_op (ADDR_EXPR, gnu_type, maybe_stable_expr);

                    gnu_size = NULL_TREE;
                    used_by_ref = true;
                  }
              }
          }

        /* Make a volatile version of this object's type if we are to make
           the object volatile.  We also interpret 13.3(19) conservatively
           and disallow any optimizations for an object covered by it.  */
        if ((Treat_As_Volatile (gnat_entity)
             || (Is_Exported (gnat_entity)
                 /* Exclude exported constants created by the compiler,
                    which should boil down to static dispatch tables and
                    make it possible to put them in read-only memory.  */
                 && (Comes_From_Source (gnat_entity) || !const_flag))
             || Is_Imported (gnat_entity)
             || Present (Address_Clause (gnat_entity)))
            && !TYPE_VOLATILE (gnu_type))
          gnu_type = build_qualified_type (gnu_type,
                                           (TYPE_QUALS (gnu_type)
                                            | TYPE_QUAL_VOLATILE));

        /* If we are defining an aliased object whose nominal subtype is
           unconstrained, the object is a record that contains both the
           template and the object.  If there is an initializer, it will
           have already been converted to the right type, but we need to
           create the template if there is no initializer.  */
        if (definition
            && !gnu_expr
            && TREE_CODE (gnu_type) == RECORD_TYPE
            && (TYPE_CONTAINS_TEMPLATE_P (gnu_type)
                /* Beware that padding might have been introduced
                   via maybe_pad_type above.  */
                || (TYPE_IS_PADDING_P (gnu_type)
                    && TREE_CODE (TREE_TYPE (TYPE_FIELDS (gnu_type)))
                       == RECORD_TYPE
                    && TYPE_CONTAINS_TEMPLATE_P
                       (TREE_TYPE (TYPE_FIELDS (gnu_type))))))
          {
            tree template_field
              = TYPE_IS_PADDING_P (gnu_type)
                ? TYPE_FIELDS (TREE_TYPE (TYPE_FIELDS (gnu_type)))
                : TYPE_FIELDS (gnu_type);

            gnu_expr
              = gnat_build_constructor
              (gnu_type,
               tree_cons
               (template_field,
                build_template (TREE_TYPE (template_field),
                                TREE_TYPE (TREE_CHAIN (template_field)),
                                NULL_TREE),
                NULL_TREE));
          }

        /* Convert the expression to the type of the object except in the
           case where the object's type is unconstrained or the object's type
           is a padded record whose field is of self-referential size.  In
           the former case, converting will generate unnecessary evaluations
           of the CONSTRUCTOR to compute the size and in the latter case, we
           want to only copy the actual data.  */
        if (gnu_expr
            && TREE_CODE (gnu_type) != UNCONSTRAINED_ARRAY_TYPE
            && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type))
            && !(TREE_CODE (gnu_type) == RECORD_TYPE
                 && TYPE_IS_PADDING_P (gnu_type)
                 && (CONTAINS_PLACEHOLDER_P
                     (TYPE_SIZE (TREE_TYPE (TYPE_FIELDS (gnu_type)))))))
          gnu_expr = convert (gnu_type, gnu_expr);

        /* If this is a pointer and it does not have an initializing
           expression, initialize it to NULL, unless the object is
           imported.  */
        if (definition
            && (POINTER_TYPE_P (gnu_type) || TYPE_FAT_POINTER_P (gnu_type))
            && !Is_Imported (gnat_entity) && !gnu_expr)
          gnu_expr = integer_zero_node;

        /* If we are defining the object and it has an Address clause, we must
           either get the address expression from the saved GCC tree for the
           object if it has a Freeze node, or elaborate the address expression
           here since the front-end has guaranteed that the elaboration has no
           effects in this case.  */
        if (definition && Present (Address_Clause (gnat_entity)))
          {
            tree gnu_address
              = present_gnu_tree (gnat_entity)
                ? get_gnu_tree (gnat_entity)
                : gnat_to_gnu (Expression (Address_Clause (gnat_entity)));

            save_gnu_tree (gnat_entity, NULL_TREE, false);

            /* Ignore the size.  It's either meaningless or was handled
               above.  */
            gnu_size = NULL_TREE;
            /* Convert the type of the object to a reference type that can
               alias everything as per 13.3(19).  */
            gnu_type
              = build_reference_type_for_mode (gnu_type, ptr_mode, true);
            gnu_address = convert (gnu_type, gnu_address);
            used_by_ref = true;
            const_flag = !Is_Public (gnat_entity)
              || compile_time_known_address_p (Expression (Address_Clause
                                                           (gnat_entity)));

            /* If this is a deferred constant, the initializer is attached to
               the full view.  */
            if (kind == E_Constant && Present (Full_View (gnat_entity)))
              gnu_expr
                = gnat_to_gnu
                    (Expression (Declaration_Node (Full_View (gnat_entity))));

            /* If we don't have an initializing expression for the underlying
               variable, the initializing expression for the pointer is the
               specified address.  Otherwise, we have to make a COMPOUND_EXPR
               to assign both the address and the initial value.  */
            if (!gnu_expr)
              gnu_expr = gnu_address;
            else
              gnu_expr
                = build2 (COMPOUND_EXPR, gnu_type,
                          build_binary_op
                          (MODIFY_EXPR, NULL_TREE,
                           build_unary_op (INDIRECT_REF, NULL_TREE,
                                           gnu_address),
                           gnu_expr),
                          gnu_address);
          }

        /* If it has an address clause and we are not defining it, mark it
           as an indirect object.  Likewise for Stdcall objects that are
           imported.  */
        if ((!definition && Present (Address_Clause (gnat_entity)))
            || (Is_Imported (gnat_entity)
                && Has_Stdcall_Convention (gnat_entity)))
          {
            /* Convert the type of the object to a reference type that can
               alias everything as per 13.3(19).  */
            gnu_type
              = build_reference_type_for_mode (gnu_type, ptr_mode, true);
            gnu_size = NULL_TREE;

            /* No point in taking the address of an initializing expression
               that isn't going to be used.  */
            gnu_expr = NULL_TREE;

            /* If it has an address clause whose value is known at compile
               time, make the object a CONST_DECL.  This will avoid a
               useless dereference.  */
            if (Present (Address_Clause (gnat_entity)))
              {
                Node_Id gnat_address
                  = Expression (Address_Clause (gnat_entity));

                if (compile_time_known_address_p (gnat_address))
                  {
                    gnu_expr = gnat_to_gnu (gnat_address);
                    const_flag = true;
                  }
              }

            used_by_ref = true;
          }

        /* If we are at top level and this object is of variable size,
           make the actual type a hidden pointer to the real type and
           make the initializer be a memory allocation and initialization.
           Likewise for objects we aren't defining (presumed to be
           external references from other packages), but there we do
           not set up an initialization.

           If the object's size overflows, make an allocator too, so that
           Storage_Error gets raised.  Note that we will never free
           such memory, so we presume it never will get allocated.  */

        if (!allocatable_size_p (TYPE_SIZE_UNIT (gnu_type),
                                 global_bindings_p () || !definition
                                 || static_p)
            || (gnu_size
                && ! allocatable_size_p (gnu_size,
                                         global_bindings_p () || !definition
                                         || static_p)))
          {
            gnu_type = build_reference_type (gnu_type);
            gnu_size = NULL_TREE;
            used_by_ref = true;
            const_flag = true;

            /* In case this was a aliased object whose nominal subtype is
               unconstrained, the pointer above will be a thin pointer and
               build_allocator will automatically make the template.

               If we have a template initializer only (that we made above),
               pretend there is none and rely on what build_allocator creates
               again anyway.  Otherwise (if we have a full initializer), get
               the data part and feed that to build_allocator.

               If we are elaborating a mutable object, tell build_allocator to
               ignore a possibly simpler size from the initializer, if any, as
               we must allocate the maximum possible size in this case.  */

            if (definition)
              {
                tree gnu_alloc_type = TREE_TYPE (gnu_type);

                if (TREE_CODE (gnu_alloc_type) == RECORD_TYPE
                    && TYPE_CONTAINS_TEMPLATE_P (gnu_alloc_type))
                  {
                    gnu_alloc_type
                      = TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_alloc_type)));

                    if (TREE_CODE (gnu_expr) == CONSTRUCTOR
                        && 1 == VEC_length (constructor_elt,
                                            CONSTRUCTOR_ELTS (gnu_expr)))
                      gnu_expr = 0;
                    else
                      gnu_expr
                        = build_component_ref
                            (gnu_expr, NULL_TREE,
                             TREE_CHAIN (TYPE_FIELDS (TREE_TYPE (gnu_expr))),
                             false);
                  }

                if (TREE_CODE (TYPE_SIZE_UNIT (gnu_alloc_type)) == INTEGER_CST
                    && TREE_OVERFLOW (TYPE_SIZE_UNIT (gnu_alloc_type))
                    && !Is_Imported (gnat_entity))
                  post_error ("?Storage_Error will be raised at run-time!",
                              gnat_entity);

                gnu_expr = build_allocator (gnu_alloc_type, gnu_expr, gnu_type,
                                            0, 0, gnat_entity, mutable_p);
              }
            else
              {
                gnu_expr = NULL_TREE;
                const_flag = false;
              }
          }

        /* If this object would go into the stack and has an alignment larger
           than the largest stack alignment the back-end can honor, resort to
           a variable of "aligning type".  */
        if (!global_bindings_p () && !static_p && definition
            && !imported_p && TYPE_ALIGN (gnu_type) > BIGGEST_ALIGNMENT)
          {
            /* Create the new variable.  No need for extra room before the
               aligned field as this is in automatic storage.  */
            tree gnu_new_type
              = make_aligning_type (gnu_type, TYPE_ALIGN (gnu_type),
                                    TYPE_SIZE_UNIT (gnu_type),
                                    BIGGEST_ALIGNMENT, 0);
            tree gnu_new_var
              = create_var_decl (create_concat_name (gnat_entity, "ALIGN"),
                                 NULL_TREE, gnu_new_type, NULL_TREE, false,
                                 false, false, false, NULL, gnat_entity);

            /* Initialize the aligned field if we have an initializer.  */
            if (gnu_expr)
              add_stmt_with_node
                (build_binary_op (MODIFY_EXPR, NULL_TREE,
                                  build_component_ref
                                  (gnu_new_var, NULL_TREE,
                                   TYPE_FIELDS (gnu_new_type), false),
                                  gnu_expr),
                 gnat_entity);

            /* And setup this entity as a reference to the aligned field.  */
            gnu_type = build_reference_type (gnu_type);
            gnu_expr
              = build_unary_op
                (ADDR_EXPR, gnu_type,
                 build_component_ref (gnu_new_var, NULL_TREE,
                                      TYPE_FIELDS (gnu_new_type), false));

            gnu_size = NULL_TREE;
            used_by_ref = true;
            const_flag = true;
          }

        if (const_flag)
          gnu_type = build_qualified_type (gnu_type, (TYPE_QUALS (gnu_type)
                                                      | TYPE_QUAL_CONST));

        /* Convert the expression to the type of the object except in the
           case where the object's type is unconstrained or the object's type
           is a padded record whose field is of self-referential size.  In
           the former case, converting will generate unnecessary evaluations
           of the CONSTRUCTOR to compute the size and in the latter case, we
           want to only copy the actual data.  */
        if (gnu_expr
            && TREE_CODE (gnu_type) != UNCONSTRAINED_ARRAY_TYPE
            && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type))
            && !(TREE_CODE (gnu_type) == RECORD_TYPE
                 && TYPE_IS_PADDING_P (gnu_type)
                 && (CONTAINS_PLACEHOLDER_P
                     (TYPE_SIZE (TREE_TYPE (TYPE_FIELDS (gnu_type)))))))
          gnu_expr = convert (gnu_type, gnu_expr);

        /* If this name is external or there was a name specified, use it,
           unless this is a VMS exception object since this would conflict
           with the symbol we need to export in addition.  Don't use the
           Interface_Name if there is an address clause (see CD30005).  */
        if (!Is_VMS_Exception (gnat_entity)
            && ((Present (Interface_Name (gnat_entity))
                 && No (Address_Clause (gnat_entity)))
                || (Is_Public (gnat_entity)
                    && (!Is_Imported (gnat_entity)
                        || Is_Exported (gnat_entity)))))
          gnu_ext_name = create_concat_name (gnat_entity, 0);

        /* If this is constant initialized to a static constant and the
           object has an aggregate type, force it to be statically
           allocated.  This will avoid an initialization copy.  */
        if (!static_p && const_flag
            && gnu_expr && TREE_CONSTANT (gnu_expr)
            && AGGREGATE_TYPE_P (gnu_type)
            && host_integerp (TYPE_SIZE_UNIT (gnu_type), 1)
            && !(TREE_CODE (gnu_type) == RECORD_TYPE
                 && TYPE_IS_PADDING_P (gnu_type)
                 && !host_integerp (TYPE_SIZE_UNIT
                                    (TREE_TYPE (TYPE_FIELDS (gnu_type))), 1)))
          static_p = true;

        gnu_decl = create_var_decl (gnu_entity_id, gnu_ext_name, gnu_type,
                                    gnu_expr, const_flag,
                                    Is_Public (gnat_entity),
                                    imported_p || !definition,
                                    static_p, attr_list, gnat_entity);
        DECL_BY_REF_P (gnu_decl) = used_by_ref;
        DECL_POINTS_TO_READONLY_P (gnu_decl) = used_by_ref && inner_const_flag;
        if (TREE_CODE (gnu_decl) == VAR_DECL && renamed_obj)
          {
            SET_DECL_RENAMED_OBJECT (gnu_decl, renamed_obj);
            if (global_bindings_p ())
              {
                DECL_RENAMING_GLOBAL_P (gnu_decl) = 1;
                record_global_renaming_pointer (gnu_decl);
              }
          }

        if (definition && DECL_SIZE_UNIT (gnu_decl)
            && get_block_jmpbuf_decl ()
            && (TREE_CODE (DECL_SIZE_UNIT (gnu_decl)) != INTEGER_CST
                || (flag_stack_check == GENERIC_STACK_CHECK
                    && compare_tree_int (DECL_SIZE_UNIT (gnu_decl),
                                         STACK_CHECK_MAX_VAR_SIZE) > 0)))
          add_stmt_with_node (build_call_1_expr
                              (update_setjmp_buf_decl,
                               build_unary_op (ADDR_EXPR, NULL_TREE,
                                               get_block_jmpbuf_decl ())),
                              gnat_entity);

        /* If we are defining an Out parameter and we're not optimizing,
           create a fake PARM_DECL for debugging purposes and make it
           point to the VAR_DECL.  Suppress debug info for the latter
           but make sure it will still live on the stack so it can be
           accessed from within the debugger through the PARM_DECL.  */
        if (kind == E_Out_Parameter && definition && !optimize)
          {
            tree param = create_param_decl (gnu_entity_id, gnu_type, false);
            gnat_pushdecl (param, gnat_entity);
            SET_DECL_VALUE_EXPR (param, gnu_decl);
            DECL_HAS_VALUE_EXPR_P (param) = 1;
            if (debug_info_p)
              debug_info_p = false;
            else
              DECL_IGNORED_P (param) = 1;
            TREE_ADDRESSABLE (gnu_decl) = 1;
          }

        /* If this is a public constant or we're not optimizing and we're not
           making a VAR_DECL for it, make one just for export or debugger use.
           Likewise if the address is taken or if either the object or type is
           aliased.  Make an external declaration for a reference, unless this
           is a Standard entity since there no real symbol at the object level
           for these.  */
        if (TREE_CODE (gnu_decl) == CONST_DECL
            && (definition || Sloc (gnat_entity) > Standard_Location)
            && ((Is_Public (gnat_entity)
                 && !Present (Address_Clause (gnat_entity)))
                || !optimize
                || Address_Taken (gnat_entity)
                || Is_Aliased (gnat_entity)
                || Is_Aliased (Etype (gnat_entity))))
          {
            tree gnu_corr_var
              = create_true_var_decl (gnu_entity_id, gnu_ext_name, gnu_type,
                                      gnu_expr, true, Is_Public (gnat_entity),
                                      !definition, static_p, NULL,
                                      gnat_entity);

            SET_DECL_CONST_CORRESPONDING_VAR (gnu_decl, gnu_corr_var);

            /* As debugging information will be generated for the variable,
               do not generate information for the constant.  */
            DECL_IGNORED_P (gnu_decl) = 1;
          }

        /* If this is declared in a block that contains a block with an
           exception handler, we must force this variable in memory to
           suppress an invalid optimization.  */
        if (Has_Nested_Block_With_Handler (Scope (gnat_entity))
            && Exception_Mechanism != Back_End_Exceptions)
          TREE_ADDRESSABLE (gnu_decl) = 1;

        gnu_type = TREE_TYPE (gnu_decl);

        /* Back-annotate Alignment and Esize of the object if not already
           known, except for when the object is actually a pointer to the
           real object, since alignment and size of a pointer don't have
           anything to do with those of the designated object.  Note that
           we pick the values of the type, not those of the object, to
           shield ourselves from low-level platform-dependent adjustments
           like alignment promotion.  This is both consistent with all the
           treatment above, where alignment and size are set on the type of
           the object and not on the object directly, and makes it possible
           to support confirming representation clauses in all cases.  */

        if (!used_by_ref && Unknown_Alignment (gnat_entity))
          Set_Alignment (gnat_entity,
                         UI_From_Int (TYPE_ALIGN (gnu_type) / BITS_PER_UNIT));

        if (!used_by_ref && Unknown_Esize (gnat_entity))
          {
            if (TREE_CODE (gnu_type) == RECORD_TYPE
                && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
              gnu_object_size
                = TYPE_SIZE (TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_type))));

            Set_Esize (gnat_entity, annotate_value (gnu_object_size));
          }
      }
      break;

    case E_Void:
      /* Return a TYPE_DECL for "void" that we previously made.  */
      gnu_decl = TYPE_NAME (void_type_node);
      break;

    case E_Enumeration_Type:
      /* A special case, for the types Character and Wide_Character in
         Standard, we do not list all the literals.  So if the literals
         are not specified, make this an unsigned type.  */
      if (No (First_Literal (gnat_entity)))
        {
          gnu_type = make_unsigned_type (esize);
          TYPE_NAME (gnu_type) = gnu_entity_id;

          /* Set TYPE_STRING_FLAG for Ada Character and Wide_Character types.
             This is needed by the DWARF-2 back-end to distinguish between
             unsigned integer types and character types.  */
          TYPE_STRING_FLAG (gnu_type) = 1;
          break;
        }

      /* Normal case of non-character type, or non-Standard character type */
      {
        /* Here we have a list of enumeral constants in First_Literal.
           We make a CONST_DECL for each and build into GNU_LITERAL_LIST
           the list to be places into TYPE_FIELDS.  Each node in the list
           is a TREE_LIST node whose TREE_VALUE is the literal name
           and whose TREE_PURPOSE is the value of the literal.

           Esize contains the number of bits needed to represent the enumeral
           type, Type_Low_Bound also points to the first literal and
           Type_High_Bound points to the last literal.  */

        Entity_Id gnat_literal;
        tree gnu_literal_list = NULL_TREE;

        if (Is_Unsigned_Type (gnat_entity))
          gnu_type = make_unsigned_type (esize);
        else
          gnu_type = make_signed_type (esize);

        TREE_SET_CODE (gnu_type, ENUMERAL_TYPE);

        for (gnat_literal = First_Literal (gnat_entity);
             Present (gnat_literal);
             gnat_literal = Next_Literal (gnat_literal))
          {
            tree gnu_value = UI_To_gnu (Enumeration_Rep (gnat_literal),
                                        gnu_type);
            tree gnu_literal
              = create_var_decl (get_entity_name (gnat_literal), NULL_TREE,
                                 gnu_type, gnu_value, true, false, false,
                                 false, NULL, gnat_literal);

            save_gnu_tree (gnat_literal, gnu_literal, false);
            gnu_literal_list = tree_cons (DECL_NAME (gnu_literal),
                                          gnu_value, gnu_literal_list);
          }

        TYPE_VALUES (gnu_type) = nreverse (gnu_literal_list);

        /* Note that the bounds are updated at the end of this function
           because to avoid an infinite recursion when we get the bounds of
           this type, since those bounds are objects of this type.    */
      }
      break;

    case E_Signed_Integer_Type:
    case E_Ordinary_Fixed_Point_Type:
    case E_Decimal_Fixed_Point_Type:
      /* For integer types, just make a signed type the appropriate number
         of bits.  */
      gnu_type = make_signed_type (esize);
      break;

    case E_Modular_Integer_Type:
      /* For modular types, make the unsigned type of the proper number of
         bits and then set up the modulus, if required.  */
      {
        enum machine_mode mode;
        tree gnu_modulus;
        tree gnu_high = 0;

        if (Is_Packed_Array_Type (gnat_entity))
          esize = UI_To_Int (RM_Size (gnat_entity));

        /* Find the smallest mode at least ESIZE bits wide and make a class
           using that mode.  */

        for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT);
             GET_MODE_BITSIZE (mode) < esize;
             mode = GET_MODE_WIDER_MODE (mode))
          ;

        gnu_type = make_unsigned_type (GET_MODE_BITSIZE (mode));
        TYPE_PACKED_ARRAY_TYPE_P (gnu_type)
          = (Is_Packed_Array_Type (gnat_entity)
             && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)));

        /* Get the modulus in this type.  If it overflows, assume it is because
           it is equal to 2**Esize.  Note that there is no overflow checking
           done on unsigned type, so we detect the overflow by looking for
           a modulus of zero, which is otherwise invalid.  */
        gnu_modulus = UI_To_gnu (Modulus (gnat_entity), gnu_type);

        if (!integer_zerop (gnu_modulus))
          {
            TYPE_MODULAR_P (gnu_type) = 1;
            SET_TYPE_MODULUS (gnu_type, gnu_modulus);
            gnu_high = fold_build2 (MINUS_EXPR, gnu_type, gnu_modulus,
                                    convert (gnu_type, integer_one_node));
          }

        /* If we have to set TYPE_PRECISION different from its natural value,
           make a subtype to do do.  Likewise if there is a modulus and
           it is not one greater than TYPE_MAX_VALUE.  */
        if (TYPE_PRECISION (gnu_type) != esize
            || (TYPE_MODULAR_P (gnu_type)
                && !tree_int_cst_equal (TYPE_MAX_VALUE (gnu_type), gnu_high)))
          {
            tree gnu_subtype = make_node (INTEGER_TYPE);

            TYPE_NAME (gnu_type) = create_concat_name (gnat_entity, "UMT");
            TREE_TYPE (gnu_subtype) = gnu_type;
            TYPE_MIN_VALUE (gnu_subtype) = TYPE_MIN_VALUE (gnu_type);
            TYPE_MAX_VALUE (gnu_subtype)
              = TYPE_MODULAR_P (gnu_type)
                ? gnu_high : TYPE_MAX_VALUE (gnu_type);
            TYPE_PRECISION (gnu_subtype) = esize;
            TYPE_UNSIGNED (gnu_subtype) = 1;
            TYPE_EXTRA_SUBTYPE_P (gnu_subtype) = 1;
            TYPE_PACKED_ARRAY_TYPE_P (gnu_subtype)
              = (Is_Packed_Array_Type (gnat_entity)
                 && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)));
            layout_type (gnu_subtype);

            gnu_type = gnu_subtype;
          }
      }
      break;

    case E_Signed_Integer_Subtype:
    case E_Enumeration_Subtype:
    case E_Modular_Integer_Subtype:
    case E_Ordinary_Fixed_Point_Subtype:
    case E_Decimal_Fixed_Point_Subtype:

      /* For integral subtypes, we make a new INTEGER_TYPE.  Note
         that we do not want to call build_range_type since we would
         like each subtype node to be distinct.  This will be important
         when memory aliasing is implemented.

         The TREE_TYPE field of the INTEGER_TYPE we make points to the
         parent type; this fact is used by the arithmetic conversion
         functions.

         We elaborate the Ancestor_Subtype if it is not in the current
         unit and one of our bounds is non-static.  We do this to ensure
         consistent naming in the case where several subtypes share the same
         bounds by always elaborating the first such subtype first, thus
         using its name.  */

      if (!definition
          && Present (Ancestor_Subtype (gnat_entity))
          && !In_Extended_Main_Code_Unit (Ancestor_Subtype (gnat_entity))
          && (!Compile_Time_Known_Value (Type_Low_Bound (gnat_entity))
              || !Compile_Time_Known_Value (Type_High_Bound (gnat_entity))))
        gnat_to_gnu_entity (Ancestor_Subtype (gnat_entity),
                            gnu_expr, 0);

      gnu_type = make_node (INTEGER_TYPE);
      TREE_TYPE (gnu_type) = get_unpadded_type (Etype (gnat_entity));

      /* Set the precision to the Esize except for bit-packed arrays and
         subtypes of Standard.Boolean.  */
      if (Is_Packed_Array_Type (gnat_entity)
          && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)))
        {
          esize = UI_To_Int (RM_Size (gnat_entity));
          TYPE_PACKED_ARRAY_TYPE_P (gnu_type) = 1;
        }
      else if (TREE_CODE (TREE_TYPE (gnu_type)) == BOOLEAN_TYPE)
        esize = 1;

      TYPE_PRECISION (gnu_type) = esize;

      TYPE_MIN_VALUE (gnu_type)
        = convert (TREE_TYPE (gnu_type),
                   elaborate_expression (Type_Low_Bound (gnat_entity),
                                         gnat_entity,
                                         get_identifier ("L"), definition, 1,
                                         Needs_Debug_Info (gnat_entity)));

      TYPE_MAX_VALUE (gnu_type)
        = convert (TREE_TYPE (gnu_type),
                   elaborate_expression (Type_High_Bound (gnat_entity),
                                         gnat_entity,
                                         get_identifier ("U"), definition, 1,
                                         Needs_Debug_Info (gnat_entity)));

      /* One of the above calls might have caused us to be elaborated,
         so don't blow up if so.  */
      if (present_gnu_tree (gnat_entity))
        {
          maybe_present = true;
          break;
        }

      TYPE_BIASED_REPRESENTATION_P (gnu_type)
        = Has_Biased_Representation (gnat_entity);

     /* This should be an unsigned type if the lower bound is constant
         and non-negative or if the base type is unsigned; a signed type
         otherwise.    */
      TYPE_UNSIGNED (gnu_type)
        = (TYPE_UNSIGNED (TREE_TYPE (gnu_type))
           || (TREE_CODE (TYPE_MIN_VALUE (gnu_type)) == INTEGER_CST
               && TREE_INT_CST_HIGH (TYPE_MIN_VALUE (gnu_type)) >= 0)
           || TYPE_BIASED_REPRESENTATION_P (gnu_type)
           || Is_Unsigned_Type (gnat_entity));

      layout_type (gnu_type);

      /* Inherit our alias set from what we're a subtype of.  Subtypes
         are not different types and a pointer can designate any instance
         within a subtype hierarchy.  */
      relate_alias_sets (gnu_type, TREE_TYPE (gnu_type), ALIAS_SET_COPY);

      /* If the type we are dealing with is to represent a packed array,
         we need to have the bits left justified on big-endian targets
         and right justified on little-endian targets.  We also need to
         ensure that when the value is read (e.g. for comparison of two
         such values), we only get the good bits, since the unused bits
         are uninitialized.  Both goals are accomplished by wrapping the
         modular value in an enclosing struct.  */
      if (Is_Packed_Array_Type (gnat_entity)
          && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)))
        {
          tree gnu_field_type = gnu_type;
          tree gnu_field;

          TYPE_RM_SIZE_NUM (gnu_field_type)
            = UI_To_gnu (RM_Size (gnat_entity), bitsizetype);
          gnu_type = make_node (RECORD_TYPE);
          TYPE_NAME (gnu_type) = create_concat_name (gnat_entity, "JM");

          /* Propagate the alignment of the modular type to the record.
             This means that bitpacked arrays have "ceil" alignment for
             their size, which may seem counter-intuitive but makes it
             possible to easily overlay them on modular types.  */
          TYPE_ALIGN (gnu_type) = TYPE_ALIGN (gnu_field_type);
          TYPE_PACKED (gnu_type) = 1;

          /* Create a stripped-down declaration of the original type, mainly
             for debugging.  */
          create_type_decl (get_entity_name (gnat_entity), gnu_field_type,
                            NULL, true, debug_info_p, gnat_entity);

          /* Don't notify the field as "addressable", since we won't be taking
             it's address and it would prevent create_field_decl from making a
             bitfield.  */
          gnu_field = create_field_decl (get_identifier ("OBJECT"),
                                         gnu_field_type, gnu_type, 1, 0, 0, 0);

          finish_record_type (gnu_type, gnu_field, 0, false);
          TYPE_JUSTIFIED_MODULAR_P (gnu_type) = 1;
          SET_TYPE_ADA_SIZE (gnu_type, bitsize_int (esize));

          relate_alias_sets (gnu_type, gnu_field_type, ALIAS_SET_COPY);
        }

      /* If the type we are dealing with has got a smaller alignment than the
         natural one, we need to wrap it up in a record type and under-align
         the latter.  We reuse the padding machinery for this purpose.  */
      else if (Known_Alignment (gnat_entity)
               && UI_Is_In_Int_Range (Alignment (gnat_entity))
               && (align = UI_To_Int (Alignment (gnat_entity)) * BITS_PER_UNIT)
               && align < TYPE_ALIGN (gnu_type))
        {
          tree gnu_field_type = gnu_type;
          tree gnu_field;

          gnu_type = make_node (RECORD_TYPE);
          TYPE_NAME (gnu_type) = create_concat_name (gnat_entity, "PAD");

          TYPE_ALIGN (gnu_type) = align;
          TYPE_PACKED (gnu_type) = 1;

          /* Create a stripped-down declaration of the original type, mainly
             for debugging.  */
          create_type_decl (get_entity_name (gnat_entity), gnu_field_type,
                            NULL, true, debug_info_p, gnat_entity);

          /* Don't notify the field as "addressable", since we won't be taking
             it's address and it would prevent create_field_decl from making a
             bitfield.  */
          gnu_field = create_field_decl (get_identifier ("OBJECT"),
                                         gnu_field_type, gnu_type, 1, 0, 0, 0);

          finish_record_type (gnu_type, gnu_field, 0, false);
          TYPE_IS_PADDING_P (gnu_type) = 1;
          SET_TYPE_ADA_SIZE (gnu_type, bitsize_int (esize));

          relate_alias_sets (gnu_type, gnu_field_type, ALIAS_SET_COPY);
        }

      /* Otherwise reset the alignment lest we computed it above.  */
      else
        align = 0;

      break;

    case E_Floating_Point_Type:
      /* If this is a VAX floating-point type, use an integer of the proper
         size.  All the operations will be handled with ASM statements.  */
      if (Vax_Float (gnat_entity))
        {
          gnu_type = make_signed_type (esize);
          TYPE_VAX_FLOATING_POINT_P (gnu_type) = 1;
          SET_TYPE_DIGITS_VALUE (gnu_type,
                                 UI_To_gnu (Digits_Value (gnat_entity),
                                            sizetype));
          break;
        }

      /* The type of the Low and High bounds can be our type if this is
         a type from Standard, so set them at the end of the function.  */
      gnu_type = make_node (REAL_TYPE);
      TYPE_PRECISION (gnu_type) = fp_size_to_prec (esize);
      layout_type (gnu_type);
      break;

    case E_Floating_Point_Subtype:
      if (Vax_Float (gnat_entity))
        {
          gnu_type = gnat_to_gnu_type (Etype (gnat_entity));
          break;
        }

      {
        if (!definition
            && Present (Ancestor_Subtype (gnat_entity))
            && !In_Extended_Main_Code_Unit (Ancestor_Subtype (gnat_entity))
            && (!Compile_Time_Known_Value (Type_Low_Bound (gnat_entity))
                || !Compile_Time_Known_Value (Type_High_Bound (gnat_entity))))
          gnat_to_gnu_entity (Ancestor_Subtype (gnat_entity),
                              gnu_expr, 0);

        gnu_type = make_node (REAL_TYPE);
        TREE_TYPE (gnu_type) = get_unpadded_type (Etype (gnat_entity));
        TYPE_PRECISION (gnu_type) = fp_size_to_prec (esize);

        TYPE_MIN_VALUE (gnu_type)
          = convert (TREE_TYPE (gnu_type),
                     elaborate_expression (Type_Low_Bound (gnat_entity),
                                           gnat_entity, get_identifier ("L"),
                                           definition, 1,
                                           Needs_Debug_Info (gnat_entity)));

        TYPE_MAX_VALUE (gnu_type)
          = convert (TREE_TYPE (gnu_type),
                     elaborate_expression (Type_High_Bound (gnat_entity),
                                           gnat_entity, get_identifier ("U"),
                                           definition, 1,
                                           Needs_Debug_Info (gnat_entity)));

        /* One of the above calls might have caused us to be elaborated,
           so don't blow up if so.  */
        if (present_gnu_tree (gnat_entity))
          {
            maybe_present = true;
            break;
          }

        layout_type (gnu_type);

        /* Inherit our alias set from what we're a subtype of, as for
           integer subtypes.  */
        relate_alias_sets (gnu_type, TREE_TYPE (gnu_type), ALIAS_SET_COPY);
      }
    break;

      /* Array and String Types and Subtypes

         Unconstrained array types are represented by E_Array_Type and
         constrained array types are represented by E_Array_Subtype.  There
         are no actual objects of an unconstrained array type; all we have
         are pointers to that type.

         The following fields are defined on array types and subtypes:

                Component_Type     Component type of the array.
                Number_Dimensions  Number of dimensions (an int).
                First_Index        Type of first index.  */

    case E_String_Type:
    case E_Array_Type:
      {
        tree gnu_template_fields = NULL_TREE;
        tree gnu_template_type = make_node (RECORD_TYPE);
        tree gnu_ptr_template = build_pointer_type (gnu_template_type);
        tree gnu_fat_type = make_node (RECORD_TYPE);
        int ndim = Number_Dimensions (gnat_entity);
        int firstdim
          = (Convention (gnat_entity) == Convention_Fortran) ? ndim - 1 : 0;
        int nextdim
          = (Convention (gnat_entity) == Convention_Fortran) ? - 1 : 1;
        int index;
        tree *gnu_index_types = (tree *) alloca (ndim * sizeof (tree *));
        tree *gnu_temp_fields = (tree *) alloca (ndim * sizeof (tree *));
        tree gnu_comp_size = 0;
        tree gnu_max_size = size_one_node;
        tree gnu_max_size_unit;
        Entity_Id gnat_ind_subtype;
        Entity_Id gnat_ind_base_subtype;
        tree gnu_template_reference;
        tree tem;

        TYPE_NAME (gnu_template_type)
          = create_concat_name (gnat_entity, "XUB");

        /* Make a node for the array.  If we are not defining the array
           suppress expanding incomplete types.  */
        gnu_type = make_node (UNCONSTRAINED_ARRAY_TYPE);

        if (!definition)
          defer_incomplete_level++, this_deferred = true;

        /* Build the fat pointer type.  Use a "void *" object instead of
           a pointer to the array type since we don't have the array type
           yet (it will reference the fat pointer via the bounds).  */
        tem = chainon (chainon (NULL_TREE,
                                create_field_decl (get_identifier ("P_ARRAY"),
                                                   ptr_void_type_node,
                                                   gnu_fat_type, 0, 0, 0, 0)),
                       create_field_decl (get_identifier ("P_BOUNDS"),
                                          gnu_ptr_template,
                                          gnu_fat_type, 0, 0, 0, 0));

        /* Make sure we can put this into a register.  */
        TYPE_ALIGN (gnu_fat_type) = MIN (BIGGEST_ALIGNMENT, 2 * POINTER_SIZE);

        /* Do not finalize this record type since the types of its fields
           are still incomplete at this point.  */
        finish_record_type (gnu_fat_type, tem, 0, true);
        TYPE_IS_FAT_POINTER_P (gnu_fat_type) = 1;

        /* Build a reference to the template from a PLACEHOLDER_EXPR that
           is the fat pointer.  This will be used to access the individual
           fields once we build them.  */
        tem = build3 (COMPONENT_REF, gnu_ptr_template,
                      build0 (PLACEHOLDER_EXPR, gnu_fat_type),
                      TREE_CHAIN (TYPE_FIELDS (gnu_fat_type)), NULL_TREE);
        gnu_template_reference
          = build_unary_op (INDIRECT_REF, gnu_template_type, tem);
        TREE_READONLY (gnu_template_reference) = 1;

        /* Now create the GCC type for each index and add the fields for
           that index to the template.  */
        for (index = firstdim, gnat_ind_subtype = First_Index (gnat_entity),
             gnat_ind_base_subtype
               = First_Index (Implementation_Base_Type (gnat_entity));
             index < ndim && index >= 0;
             index += nextdim,
             gnat_ind_subtype = Next_Index (gnat_ind_subtype),
             gnat_ind_base_subtype = Next_Index (gnat_ind_base_subtype))
          {
            char field_name[10];
            tree gnu_ind_subtype
              = get_unpadded_type (Base_Type (Etype (gnat_ind_subtype)));
            tree gnu_base_subtype
              = get_unpadded_type (Etype (gnat_ind_base_subtype));
            tree gnu_base_min
              = convert (sizetype, TYPE_MIN_VALUE (gnu_base_subtype));
            tree gnu_base_max
              = convert (sizetype, TYPE_MAX_VALUE (gnu_base_subtype));
            tree gnu_min_field, gnu_max_field, gnu_min, gnu_max;

            /* Make the FIELD_DECLs for the minimum and maximum of this
               type and then make extractions of that field from the
               template.  */
            sprintf (field_name, "LB%d", index);
            gnu_min_field = create_field_decl (get_identifier (field_name),
                                               gnu_ind_subtype,
                                               gnu_template_type, 0, 0, 0, 0);
            field_name[0] = 'U';
            gnu_max_field = create_field_decl (get_identifier (field_name),
                                               gnu_ind_subtype,
                                               gnu_template_type, 0, 0, 0, 0);

            Sloc_to_locus (Sloc (gnat_entity),
                           &DECL_SOURCE_LOCATION (gnu_min_field));
            Sloc_to_locus (Sloc (gnat_entity),
                           &DECL_SOURCE_LOCATION (gnu_max_field));
            gnu_temp_fields[index] = chainon (gnu_min_field, gnu_max_field);

            /* We can't use build_component_ref here since the template
               type isn't complete yet.  */
            gnu_min = build3 (COMPONENT_REF, gnu_ind_subtype,
                              gnu_template_reference, gnu_min_field,
                              NULL_TREE);
            gnu_max = build3 (COMPONENT_REF, gnu_ind_subtype,
                              gnu_template_reference, gnu_max_field,
                              NULL_TREE);
            TREE_READONLY (gnu_min) = TREE_READONLY (gnu_max) = 1;

            /* Make a range type with the new ranges, but using
               the Ada subtype.  Then we convert to sizetype.  */
            gnu_index_types[index]
              = create_index_type (convert (sizetype, gnu_min),
                                   convert (sizetype, gnu_max),
                                   build_range_type (gnu_ind_subtype,
                                                     gnu_min, gnu_max),
                                   gnat_entity);
            /* Update the maximum size of the array, in elements.  */
            gnu_max_size
              = size_binop (MULT_EXPR, gnu_max_size,
                            size_binop (PLUS_EXPR, size_one_node,
                                        size_binop (MINUS_EXPR, gnu_base_max,
                                                    gnu_base_min)));

            TYPE_NAME (gnu_index_types[index])
              = create_concat_name (gnat_entity, field_name);
          }

        for (index = 0; index < ndim; index++)
          gnu_template_fields
            = chainon (gnu_template_fields, gnu_temp_fields[index]);

        /* Install all the fields into the template.  */
        finish_record_type (gnu_template_type, gnu_template_fields, 0, false);
        TYPE_READONLY (gnu_template_type) = 1;

        /* Now make the array of arrays and update the pointer to the array
           in the fat pointer.  Note that it is the first field.  */
        tem = gnat_to_gnu_type (Component_Type (gnat_entity));

        /* Try to get a smaller form of the component if needed.  */
        if ((Is_Packed (gnat_entity)
             || Has_Component_Size_Clause (gnat_entity))
            && !Is_Bit_Packed_Array (gnat_entity)
            && !Has_Aliased_Components (gnat_entity)
            && !Strict_Alignment (Component_Type (gnat_entity))
            && TREE_CODE (tem) == RECORD_TYPE
            && !TYPE_IS_FAT_POINTER_P (tem)
            && host_integerp (TYPE_SIZE (tem), 1))
          tem = make_packable_type (tem, false);

        if (Has_Atomic_Components (gnat_entity))
          check_ok_for_atomic (tem, gnat_entity, true);

        /* Get and validate any specified Component_Size, but if Packed,
           ignore it since the front end will have taken care of it.  */
        gnu_comp_size
          = validate_size (Component_Size (gnat_entity), tem,
                           gnat_entity,
                           (Is_Bit_Packed_Array (gnat_entity)
                            ? TYPE_DECL : VAR_DECL),
                           true, Has_Component_Size_Clause (gnat_entity));

        /* If the component type is a RECORD_TYPE that has a self-referential
           size, use the maximum size.  */
        if (!gnu_comp_size && TREE_CODE (tem) == RECORD_TYPE
            && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (tem)))
          gnu_comp_size = max_size (TYPE_SIZE (tem), true);

        if (gnu_comp_size && !Is_Bit_Packed_Array (gnat_entity))
          {
            tree orig_tem;
            tem = make_type_from_size (tem, gnu_comp_size, false);
            orig_tem = tem;
            tem = maybe_pad_type (tem, gnu_comp_size, 0, gnat_entity,
                                  "C_PAD", false, definition, true);
            /* If a padding record was made, declare it now since it will
               never be declared otherwise.  This is necessary to ensure
               that its subtrees are properly marked.  */
            if (tem != orig_tem)
              create_type_decl (TYPE_NAME (tem), tem, NULL, true,
                                debug_info_p, gnat_entity);
          }

        if (Has_Volatile_Components (gnat_entity))
          tem = build_qualified_type (tem,
                                      TYPE_QUALS (tem) | TYPE_QUAL_VOLATILE);

        /* If Component_Size is not already specified, annotate it with the
           size of the component.  */
        if (Unknown_Component_Size (gnat_entity))
          Set_Component_Size (gnat_entity, annotate_value (TYPE_SIZE (tem)));

        gnu_max_size_unit = size_binop (MAX_EXPR, size_zero_node,
                                        size_binop (MULT_EXPR, gnu_max_size,
                                                    TYPE_SIZE_UNIT (tem)));
        gnu_max_size = size_binop (MAX_EXPR, bitsize_zero_node,
                                   size_binop (MULT_EXPR,
                                               convert (bitsizetype,
                                                        gnu_max_size),
                                               TYPE_SIZE (tem)));

        for (index = ndim - 1; index >= 0; index--)
          {
            tem = build_array_type (tem, gnu_index_types[index]);
            TYPE_MULTI_ARRAY_P (tem) = (index > 0);
            if (array_type_has_nonaliased_component (gnat_entity, tem))
              TYPE_NONALIASED_COMPONENT (tem) = 1;
          }

        /* If an alignment is specified, use it if valid.  But ignore it for
           types that represent the unpacked base type for packed arrays.  If
           the alignment was requested with an explicit user alignment clause,
           state so.  */
        if (No (Packed_Array_Type (gnat_entity))
            && Known_Alignment (gnat_entity))
          {
            gcc_assert (Present (Alignment (gnat_entity)));
            TYPE_ALIGN (tem)
              = validate_alignment (Alignment (gnat_entity), gnat_entity,
                                    TYPE_ALIGN (tem));
            if (Present (Alignment_Clause (gnat_entity)))
              TYPE_USER_ALIGN (tem) = 1;
          }

        TYPE_CONVENTION_FORTRAN_P (tem)
          = (Convention (gnat_entity) == Convention_Fortran);
        TREE_TYPE (TYPE_FIELDS (gnu_fat_type)) = build_pointer_type (tem);

        /* The result type is an UNCONSTRAINED_ARRAY_TYPE that indicates the
           corresponding fat pointer.  */
        TREE_TYPE (gnu_type) = TYPE_POINTER_TO (gnu_type)
          = TYPE_REFERENCE_TO (gnu_type) = gnu_fat_type;
        SET_TYPE_MODE (gnu_type, BLKmode);
        TYPE_ALIGN (gnu_type) = TYPE_ALIGN (tem);
        SET_TYPE_UNCONSTRAINED_ARRAY (gnu_fat_type, gnu_type);

        /* If the maximum size doesn't overflow, use it.  */
        if (TREE_CODE (gnu_max_size) == INTEGER_CST
            && !TREE_OVERFLOW (gnu_max_size))
          TYPE_SIZE (tem)
            = size_binop (MIN_EXPR, gnu_max_size, TYPE_SIZE (tem));
        if (TREE_CODE (gnu_max_size_unit) == INTEGER_CST
            && !TREE_OVERFLOW (gnu_max_size_unit))
          TYPE_SIZE_UNIT (tem)
            = size_binop (MIN_EXPR, gnu_max_size_unit,
                          TYPE_SIZE_UNIT (tem));

        create_type_decl (create_concat_name (gnat_entity, "XUA"),
                          tem, NULL, !Comes_From_Source (gnat_entity),
                          debug_info_p, gnat_entity);

        /* Give the fat pointer type a name.  */
        create_type_decl (create_concat_name (gnat_entity, "XUP"),
                          gnu_fat_type, NULL, true,
                          debug_info_p, gnat_entity);

       /* Create the type to be used as what a thin pointer designates: an
          record type for the object and its template with the field offsets
          shifted to have the template at a negative offset.  */
        tem = build_unc_object_type (gnu_template_type, tem,
                                     create_concat_name (gnat_entity, "XUT"));
        shift_unc_components_for_thin_pointers (tem);

        SET_TYPE_UNCONSTRAINED_ARRAY (tem, gnu_type);
        TYPE_OBJECT_RECORD_TYPE (gnu_type) = tem;

        /* Give the thin pointer type a name.  */
        create_type_decl (create_concat_name (gnat_entity, "XUX"),
                          build_pointer_type (tem), NULL, true,
                          debug_info_p, gnat_entity);
      }
      break;

    case E_String_Subtype:
    case E_Array_Subtype:

      /* This is the actual data type for array variables.  Multidimensional
         arrays are implemented in the gnu tree as arrays of arrays.  Note
         that for the moment arrays which have sparse enumeration subtypes as
         index components create sparse arrays, which is obviously space
         inefficient but so much easier to code for now.

         Also note that the subtype never refers to the unconstrained
         array type, which is somewhat at variance with Ada semantics.

         First check to see if this is simply a renaming of the array
         type.  If so, the result is the array type.  */

      gnu_type = gnat_to_gnu_type (Etype (gnat_entity));
      if (!Is_Constrained (gnat_entity))
        break;
      else
        {
          int index;
          int array_dim = Number_Dimensions (gnat_entity);
          int first_dim
            = ((Convention (gnat_entity) == Convention_Fortran)
               ? array_dim - 1 : 0);
          int next_dim
            = (Convention (gnat_entity) == Convention_Fortran) ? -1 : 1;
          Entity_Id gnat_ind_subtype;
          Entity_Id gnat_ind_base_subtype;
          tree gnu_base_type = gnu_type;
          tree *gnu_index_type = (tree *) alloca (array_dim * sizeof (tree *));
          tree gnu_comp_size = NULL_TREE;
          tree gnu_max_size = size_one_node;
          tree gnu_max_size_unit;
          bool need_index_type_struct = false;
          bool max_overflow = false;

          /* First create the gnu types for each index.  Create types for
             debugging information to point to the index types if the
             are not integer types, have variable bounds, or are
             wider than sizetype.  */

          for (index = first_dim, gnat_ind_subtype = First_Index (gnat_entity),
               gnat_ind_base_subtype
                 = First_Index (Implementation_Base_Type (gnat_entity));
               index < array_dim && index >= 0;
               index += next_dim,
               gnat_ind_subtype = Next_Index (gnat_ind_subtype),
               gnat_ind_base_subtype = Next_Index (gnat_ind_base_subtype))
            {
              tree gnu_index_subtype
                = get_unpadded_type (Etype (gnat_ind_subtype));
              tree gnu_min
                = convert (sizetype, TYPE_MIN_VALUE (gnu_index_subtype));
              tree gnu_max
                = convert (sizetype, TYPE_MAX_VALUE (gnu_index_subtype));
              tree gnu_base_subtype
                = get_unpadded_type (Etype (gnat_ind_base_subtype));
              tree gnu_base_min
                = convert (sizetype, TYPE_MIN_VALUE (gnu_base_subtype));
              tree gnu_base_max
                = convert (sizetype, TYPE_MAX_VALUE (gnu_base_subtype));
              tree gnu_base_type = get_base_type (gnu_base_subtype);
              tree gnu_base_base_min
                = convert (sizetype, TYPE_MIN_VALUE (gnu_base_type));
              tree gnu_base_base_max
                = convert (sizetype, TYPE_MAX_VALUE (gnu_base_type));
              tree gnu_high;
              tree gnu_this_max;

              /* If the minimum and maximum values both overflow in
                 SIZETYPE, but the difference in the original type
                 does not overflow in SIZETYPE, ignore the overflow
                 indications.  */
              if ((TYPE_PRECISION (gnu_index_subtype)
                   > TYPE_PRECISION (sizetype)
                   || TYPE_UNSIGNED (gnu_index_subtype)
                      != TYPE_UNSIGNED (sizetype))
                  && TREE_CODE (gnu_min) == INTEGER_CST
                  && TREE_CODE (gnu_max) == INTEGER_CST
                  && TREE_OVERFLOW (gnu_min) && TREE_OVERFLOW (gnu_max)
                  && (!TREE_OVERFLOW
                      (fold_build2 (MINUS_EXPR, gnu_index_subtype,
                                    TYPE_MAX_VALUE (gnu_index_subtype),
                                    TYPE_MIN_VALUE (gnu_index_subtype)))))
                {
                  TREE_OVERFLOW (gnu_min) = 0;
                  TREE_OVERFLOW (gnu_max) = 0;
                }

              /* Similarly, if the range is null, use bounds of 1..0 for
                 the sizetype bounds.  */
              else if ((TYPE_PRECISION (gnu_index_subtype)
                        > TYPE_PRECISION (sizetype)
                       || TYPE_UNSIGNED (gnu_index_subtype)
                          != TYPE_UNSIGNED (sizetype))
                       && TREE_CODE (gnu_min) == INTEGER_CST
                       && TREE_CODE (gnu_max) == INTEGER_CST
                       && (TREE_OVERFLOW (gnu_min) || TREE_OVERFLOW (gnu_max))
                       && tree_int_cst_lt (TYPE_MAX_VALUE (gnu_index_subtype),
                                           TYPE_MIN_VALUE (gnu_index_subtype)))
                gnu_min = size_one_node, gnu_max = size_zero_node;

              /* Now compute the size of this bound.  We need to provide
                 GCC with an upper bound to use but have to deal with the
                 "superflat" case.  There are three ways to do this.  If we
                 can prove that the array can never be superflat, we can
                 just use the high bound of the index subtype.  If we can
                 prove that the low bound minus one can't overflow, we
                 can do this as MAX (hb, lb - 1).  Otherwise, we have to use
                 the expression hb >= lb ? hb : lb - 1.  */
              gnu_high = size_binop (MINUS_EXPR, gnu_min, size_one_node);

              /* See if the base array type is already flat.  If it is, we
                 are probably compiling an ACVC test, but it will cause the
                 code below to malfunction if we don't handle it specially.  */
              if (TREE_CODE (gnu_base_min) == INTEGER_CST
                  && TREE_CODE (gnu_base_max) == INTEGER_CST
                  && !TREE_OVERFLOW (gnu_base_min)
                  && !TREE_OVERFLOW (gnu_base_max)
                  && tree_int_cst_lt (gnu_base_max, gnu_base_min))
                gnu_high = size_zero_node, gnu_min = size_one_node;

              /* If gnu_high is now an integer which overflowed, the array
                 cannot be superflat.  */
              else if (TREE_CODE (gnu_high) == INTEGER_CST
                       && TREE_OVERFLOW (gnu_high))
                gnu_high = gnu_max;
              else if (TYPE_UNSIGNED (gnu_base_subtype)
                       || TREE_CODE (gnu_high) == INTEGER_CST)
                gnu_high = size_binop (MAX_EXPR, gnu_max, gnu_high);
              else
                gnu_high
                  = build_cond_expr
                    (sizetype, build_binary_op (GE_EXPR, integer_type_node,
                                                gnu_max, gnu_min),
                     gnu_max, gnu_high);

              gnu_index_type[index]
                = create_index_type (gnu_min, gnu_high, gnu_index_subtype,
                                     gnat_entity);

              /* Also compute the maximum size of the array.  Here we
                 see if any constraint on the index type of the base type
                 can be used in the case of self-referential bound on
                 the index type of the subtype.  We look for a non-"infinite"
                 and non-self-referential bound from any type involved and
                 handle each bound separately.  */

              if ((TREE_CODE (gnu_min) == INTEGER_CST
                   && !TREE_OVERFLOW (gnu_min)
                   && !operand_equal_p (gnu_min, gnu_base_base_min, 0))
                  || !CONTAINS_PLACEHOLDER_P (gnu_min)
                  || !(TREE_CODE (gnu_base_min) == INTEGER_CST
                       && !TREE_OVERFLOW (gnu_base_min)))
                gnu_base_min = gnu_min;

              if ((TREE_CODE (gnu_max) == INTEGER_CST
                   && !TREE_OVERFLOW (gnu_max)
                   && !operand_equal_p (gnu_max, gnu_base_base_max, 0))
                  || !CONTAINS_PLACEHOLDER_P (gnu_max)
                  || !(TREE_CODE (gnu_base_max) == INTEGER_CST
                       && !TREE_OVERFLOW (gnu_base_max)))
                gnu_base_max = gnu_max;

              if ((TREE_CODE (gnu_base_min) == INTEGER_CST
                   && TREE_OVERFLOW (gnu_base_min))
                  || operand_equal_p (gnu_base_min, gnu_base_base_min, 0)
                  || (TREE_CODE (gnu_base_max) == INTEGER_CST
                      && TREE_OVERFLOW (gnu_base_max))
                  || operand_equal_p (gnu_base_max, gnu_base_base_max, 0))
                max_overflow = true;

              gnu_base_min = size_binop (MAX_EXPR, gnu_base_min, gnu_min);
              gnu_base_max = size_binop (MIN_EXPR, gnu_base_max, gnu_max);

              gnu_this_max
                = size_binop (MAX_EXPR,
                              size_binop (PLUS_EXPR, size_one_node,
                                          size_binop (MINUS_EXPR, gnu_base_max,
                                                      gnu_base_min)),
                              size_zero_node);

              if (TREE_CODE (gnu_this_max) == INTEGER_CST
                  && TREE_OVERFLOW (gnu_this_max))
                max_overflow = true;

              gnu_max_size
                = size_binop (MULT_EXPR, gnu_max_size, gnu_this_max);

              if (!integer_onep (TYPE_MIN_VALUE (gnu_index_subtype))
                  || (TREE_CODE (TYPE_MAX_VALUE (gnu_index_subtype))
                      != INTEGER_CST)
                  || TREE_CODE (gnu_index_subtype) != INTEGER_TYPE
                  || (TREE_TYPE (gnu_index_subtype)
                      && (TREE_CODE (TREE_TYPE (gnu_index_subtype))
                          != INTEGER_TYPE))
                  || TYPE_BIASED_REPRESENTATION_P (gnu_index_subtype)
                  || (TYPE_PRECISION (gnu_index_subtype)
                      > TYPE_PRECISION (sizetype)))
                need_index_type_struct = true;
            }

          /* Then flatten: create the array of arrays.  For an array type
             used to implement a packed array, get the component type from
             the original array type since the representation clauses that
             can affect it are on the latter.  */
          if (Is_Packed_Array_Type (gnat_entity)
              && !Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)))
            {
              gnu_type = gnat_to_gnu_type (Original_Array_Type (gnat_entity));
              for (index = array_dim - 1; index >= 0; index--)
                gnu_type = TREE_TYPE (gnu_type);

              /* One of the above calls might have caused us to be elaborated,
                 so don't blow up if so.  */
              if (present_gnu_tree (gnat_entity))
                {
                  maybe_present = true;
                  break;
                }
            }
          else
            {
              gnu_type = gnat_to_gnu_type (Component_Type (gnat_entity));

              /* One of the above calls might have caused us to be elaborated,
                 so don't blow up if so.  */
              if (present_gnu_tree (gnat_entity))
                {
                  maybe_present = true;
                  break;
                }

              /* Try to get a smaller form of the component if needed.  */
              if ((Is_Packed (gnat_entity)
                   || Has_Component_Size_Clause (gnat_entity))
                  && !Is_Bit_Packed_Array (gnat_entity)
                  && !Has_Aliased_Components (gnat_entity)
                  && !Strict_Alignment (Component_Type (gnat_entity))
                  && TREE_CODE (gnu_type) == RECORD_TYPE
                  && !TYPE_IS_FAT_POINTER_P (gnu_type)
                  && host_integerp (TYPE_SIZE (gnu_type), 1))
                gnu_type = make_packable_type (gnu_type, false);

              /* Get and validate any specified Component_Size, but if Packed,
                 ignore it since the front end will have taken care of it.  */
              gnu_comp_size
                = validate_size (Component_Size (gnat_entity), gnu_type,
                                 gnat_entity,
                                 (Is_Bit_Packed_Array (gnat_entity)
                                  ? TYPE_DECL : VAR_DECL), true,
                                 Has_Component_Size_Clause (gnat_entity));

              /* If the component type is a RECORD_TYPE that has a
                 self-referential size, use the maximum size.  */
              if (!gnu_comp_size
                  && TREE_CODE (gnu_type) == RECORD_TYPE
                  && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type)))
                gnu_comp_size = max_size (TYPE_SIZE (gnu_type), true);

              if (gnu_comp_size && !Is_Bit_Packed_Array (gnat_entity))
                {
                  tree orig_gnu_type;
                  gnu_type
                    = make_type_from_size (gnu_type, gnu_comp_size, false);
                  orig_gnu_type = gnu_type;
                  gnu_type = maybe_pad_type (gnu_type, gnu_comp_size, 0,
                                             gnat_entity, "C_PAD", false,
                                             definition, true);
                  /* If a padding record was made, declare it now since it
                     will never be declared otherwise.  This is necessary
                     to ensure that its subtrees are properly marked.  */
                  if (gnu_type != orig_gnu_type)
                    create_type_decl (TYPE_NAME (gnu_type), gnu_type, NULL,
                                      true, debug_info_p, gnat_entity);
                }

              if (Has_Volatile_Components (Base_Type (gnat_entity)))
                gnu_type = build_qualified_type (gnu_type,
                                                 (TYPE_QUALS (gnu_type)
                                                  | TYPE_QUAL_VOLATILE));
            }

          gnu_max_size_unit = size_binop (MULT_EXPR, gnu_max_size,
                                          TYPE_SIZE_UNIT (gnu_type));
          gnu_max_size = size_binop (MULT_EXPR,
                                     convert (bitsizetype, gnu_max_size),
                                     TYPE_SIZE (gnu_type));

          for (index = array_dim - 1; index >= 0; index --)
            {
              gnu_type = build_array_type (gnu_type, gnu_index_type[index]);
              TYPE_MULTI_ARRAY_P (gnu_type) = (index > 0);
              if (array_type_has_nonaliased_component (gnat_entity, gnu_type))
                TYPE_NONALIASED_COMPONENT (gnu_type) = 1;
            }

          /* Attach the TYPE_STUB_DECL in case we have a parallel type.  */
          if (need_index_type_struct)
            TYPE_STUB_DECL (gnu_type)
              = create_type_stub_decl (gnu_entity_id, gnu_type);

          /* If we are at file level and this is a multi-dimensional array, we
             need to make a variable corresponding to the stride of the
             inner dimensions.   */
          if (global_bindings_p () && array_dim > 1)
            {
              tree gnu_str_name = get_identifier ("ST");
              tree gnu_arr_type;

              for (gnu_arr_type = TREE_TYPE (gnu_type);
                   TREE_CODE (gnu_arr_type) == ARRAY_TYPE;
                   gnu_arr_type = TREE_TYPE (gnu_arr_type),
                   gnu_str_name = concat_id_with_name (gnu_str_name, "ST"))
                {
                  tree eltype = TREE_TYPE (gnu_arr_type);

                  TYPE_SIZE (gnu_arr_type)
                    = elaborate_expression_1 (gnat_entity, gnat_entity,
                                              TYPE_SIZE (gnu_arr_type),
                                              gnu_str_name, definition, 0);

                  /* ??? For now, store the size as a multiple of the
                     alignment of the element type in bytes so that we
                     can see the alignment from the tree.  */
                  TYPE_SIZE_UNIT (gnu_arr_type)
                    = build_binary_op
                      (MULT_EXPR, sizetype,
                       elaborate_expression_1
                       (gnat_entity, gnat_entity,
                        build_binary_op (EXACT_DIV_EXPR, sizetype,
                                         TYPE_SIZE_UNIT (gnu_arr_type),
                                         size_int (TYPE_ALIGN (eltype)
                                                   / BITS_PER_UNIT)),
                        concat_id_with_name (gnu_str_name, "A_U"),
                        definition, 0),
                       size_int (TYPE_ALIGN (eltype) / BITS_PER_UNIT));

                  /* ??? create_type_decl is not invoked on the inner types so
                     the MULT_EXPR node built above will never be marked.  */
                  mark_visited (&TYPE_SIZE_UNIT (gnu_arr_type));
                }
            }

          /* If we need to write out a record type giving the names of
             the bounds, do it now.  Make sure to reference the index
             types themselves, not just their names, as the debugger
             may fall back on them in some cases.  */
          if (need_index_type_struct && debug_info_p)
            {
              tree gnu_bound_rec = make_node (RECORD_TYPE);
              tree gnu_field_list = NULL_TREE;
              tree gnu_field;

              TYPE_NAME (gnu_bound_rec)
                = create_concat_name (gnat_entity, "XA");

              for (index = array_dim - 1; index >= 0; index--)
                {
                  tree gnu_index = TYPE_INDEX_TYPE (gnu_index_type[index]);
                  tree gnu_index_name = TYPE_NAME (gnu_index);

                  if (TREE_CODE (gnu_index_name) == TYPE_DECL)
                    gnu_index_name = DECL_NAME (gnu_index_name);

                  gnu_field = create_field_decl (gnu_index_name, gnu_index,
                                                 gnu_bound_rec,
                                                 0, NULL_TREE, NULL_TREE, 0);
                  TREE_CHAIN (gnu_field) = gnu_field_list;
                  gnu_field_list = gnu_field;
                }

              finish_record_type (gnu_bound_rec, gnu_field_list, 0, false);
              add_parallel_type (TYPE_STUB_DECL (gnu_type), gnu_bound_rec);
            }

          TYPE_CONVENTION_FORTRAN_P (gnu_type)
            = (Convention (gnat_entity) == Convention_Fortran);
          TYPE_PACKED_ARRAY_TYPE_P (gnu_type)
            = (Is_Packed_Array_Type (gnat_entity)
               && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)));

          /* If our size depends on a placeholder and the maximum size doesn't
             overflow, use it.  */
          if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type))
              && !(TREE_CODE (gnu_max_size) == INTEGER_CST
                   && TREE_OVERFLOW (gnu_max_size))
              && !(TREE_CODE (gnu_max_size_unit) == INTEGER_CST
                   && TREE_OVERFLOW (gnu_max_size_unit))
              && !max_overflow)
            {
              TYPE_SIZE (gnu_type) = size_binop (MIN_EXPR, gnu_max_size,
                                                 TYPE_SIZE (gnu_type));
              TYPE_SIZE_UNIT (gnu_type)
                = size_binop (MIN_EXPR, gnu_max_size_unit,
                              TYPE_SIZE_UNIT (gnu_type));
            }

          /* Set our alias set to that of our base type.  This gives all
             array subtypes the same alias set.  */
          relate_alias_sets (gnu_type, gnu_base_type, ALIAS_SET_COPY);
        }

      /* If this is a packed type, make this type the same as the packed
         array type, but do some adjusting in the type first.  */
      if (Present (Packed_Array_Type (gnat_entity)))
        {
          Entity_Id gnat_index;
          tree gnu_inner_type;

          /* First finish the type we had been making so that we output
             debugging information for it.  */
          gnu_type
            = build_qualified_type (gnu_type,
                                    (TYPE_QUALS (gnu_type)
                                     | (TYPE_QUAL_VOLATILE
                                        * Treat_As_Volatile (gnat_entity))));

          /* Make it artificial only if the base type was artificial as well.
             That's sort of "morally" true and will make it possible for the
             debugger to look it up by name in DWARF more easily.  */
          gnu_decl
            = create_type_decl (gnu_entity_id, gnu_type, attr_list,
                                !Comes_From_Source (gnat_entity)
                                && !Comes_From_Source (Etype (gnat_entity)),
                                debug_info_p, gnat_entity);

          /* Save it as our equivalent in case the call below elaborates
             this type again.  */
          save_gnu_tree (gnat_entity, gnu_decl, false);

          gnu_decl = gnat_to_gnu_entity (Packed_Array_Type (gnat_entity),
                                         NULL_TREE, 0);
          this_made_decl = true;
          gnu_type = TREE_TYPE (gnu_decl);
          save_gnu_tree (gnat_entity, NULL_TREE, false);

          gnu_inner_type = gnu_type;
          while (TREE_CODE (gnu_inner_type) == RECORD_TYPE
                 && (TYPE_JUSTIFIED_MODULAR_P (gnu_inner_type)
                     || TYPE_IS_PADDING_P (gnu_inner_type)))
            gnu_inner_type = TREE_TYPE (TYPE_FIELDS (gnu_inner_type));

          /* We need to point the type we just made to our index type so
             the actual bounds can be put into a template.  */

          if ((TREE_CODE (gnu_inner_type) == ARRAY_TYPE
               && !TYPE_ACTUAL_BOUNDS (gnu_inner_type))
              || (TREE_CODE (gnu_inner_type) == INTEGER_TYPE
                  && !TYPE_HAS_ACTUAL_BOUNDS_P (gnu_inner_type)))
            {
              if (TREE_CODE (gnu_inner_type) == INTEGER_TYPE)
                {
                  /* The TYPE_ACTUAL_BOUNDS field is also used for the modulus.
                     If it is, we need to make another type.  */
                  if (TYPE_MODULAR_P (gnu_inner_type))
                    {
                      tree gnu_subtype;

                      gnu_subtype = make_node (INTEGER_TYPE);

                      TREE_TYPE (gnu_subtype) = gnu_inner_type;
                      TYPE_MIN_VALUE (gnu_subtype)
                        = TYPE_MIN_VALUE (gnu_inner_type);
                      TYPE_MAX_VALUE (gnu_subtype)
                        = TYPE_MAX_VALUE (gnu_inner_type);
                      TYPE_PRECISION (gnu_subtype)
                        = TYPE_PRECISION (gnu_inner_type);
                      TYPE_UNSIGNED (gnu_subtype)
                        = TYPE_UNSIGNED (gnu_inner_type);
                      TYPE_EXTRA_SUBTYPE_P (gnu_subtype) = 1;
                      layout_type (gnu_subtype);

                      gnu_inner_type = gnu_subtype;
                    }

                  TYPE_HAS_ACTUAL_BOUNDS_P (gnu_inner_type) = 1;
                }

              SET_TYPE_ACTUAL_BOUNDS (gnu_inner_type, NULL_TREE);

              for (gnat_index = First_Index (gnat_entity);
                   Present (gnat_index); gnat_index = Next_Index (gnat_index))
                SET_TYPE_ACTUAL_BOUNDS
                  (gnu_inner_type,
                   tree_cons (NULL_TREE,
                              get_unpadded_type (Etype (gnat_index)),
                              TYPE_ACTUAL_BOUNDS (gnu_inner_type)));

              if (Convention (gnat_entity) != Convention_Fortran)
                SET_TYPE_ACTUAL_BOUNDS
                  (gnu_inner_type,
                   nreverse (TYPE_ACTUAL_BOUNDS (gnu_inner_type)));

              if (TREE_CODE (gnu_type) == RECORD_TYPE
                  && TYPE_JUSTIFIED_MODULAR_P (gnu_type))
                TREE_TYPE (TYPE_FIELDS (gnu_type)) = gnu_inner_type;
            }
        }

      /* Abort if packed array with no packed array type field set.  */
      else
        gcc_assert (!Is_Packed (gnat_entity));

      break;

    case E_String_Literal_Subtype:
      /* Create the type for a string literal.  */
      {
        Entity_Id gnat_full_type
          = (IN (Ekind (Etype (gnat_entity)), Private_Kind)
             && Present (Full_View (Etype (gnat_entity)))
             ? Full_View (Etype (gnat_entity)) : Etype (gnat_entity));
        tree gnu_string_type = get_unpadded_type (gnat_full_type);
        tree gnu_string_array_type
          = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_string_type))));
        tree gnu_string_index_type
          = get_base_type (TREE_TYPE (TYPE_INDEX_TYPE
                                      (TYPE_DOMAIN (gnu_string_array_type))));
        tree gnu_lower_bound
          = convert (gnu_string_index_type,
                     gnat_to_gnu (String_Literal_Low_Bound (gnat_entity)));
        int length = UI_To_Int (String_Literal_Length (gnat_entity));
        tree gnu_length = ssize_int (length - 1);
        tree gnu_upper_bound
          = build_binary_op (PLUS_EXPR, gnu_string_index_type,
                             gnu_lower_bound,
                             convert (gnu_string_index_type, gnu_length));
        tree gnu_range_type
          = build_range_type (gnu_string_index_type,
                              gnu_lower_bound, gnu_upper_bound);
        tree gnu_index_type
          = create_index_type (convert (sizetype,
                                        TYPE_MIN_VALUE (gnu_range_type)),
                               convert (sizetype,
                                        TYPE_MAX_VALUE (gnu_range_type)),
                               gnu_range_type, gnat_entity);

        gnu_type
          = build_array_type (gnat_to_gnu_type (Component_Type (gnat_entity)),
                              gnu_index_type);
        if (array_type_has_nonaliased_component (gnat_entity, gnu_type))
          TYPE_NONALIASED_COMPONENT (gnu_type) = 1;
        relate_alias_sets (gnu_type, gnu_string_type, ALIAS_SET_COPY);
      }
      break;

    /* Record Types and Subtypes

       The following fields are defined on record types:

                Has_Discriminants       True if the record has discriminants
                First_Discriminant      Points to head of list of discriminants
                First_Entity            Points to head of list of fields
                Is_Tagged_Type          True if the record is tagged

       Implementation of Ada records and discriminated records:

       A record type definition is transformed into the equivalent of a C
       struct definition.  The fields that are the discriminants which are
       found in the Full_Type_Declaration node and the elements of the
       Component_List found in the Record_Type_Definition node.  The
       Component_List can be a recursive structure since each Variant of
       the Variant_Part of the Component_List has a Component_List.

       Processing of a record type definition comprises starting the list of
       field declarations here from the discriminants and the calling the
       function components_to_record to add the rest of the fields from the
       component list and return the gnu type node.  The function
       components_to_record will call itself recursively as it traverses
       the tree.  */

    case E_Record_Type:
      if (Has_Complex_Representation (gnat_entity))
        {
          gnu_type
            = build_complex_type
              (get_unpadded_type
               (Etype (Defining_Entity
                       (First (Component_Items
                               (Component_List
                                (Type_Definition
                                 (Declaration_Node (gnat_entity)))))))));

          break;
        }

      {
        Node_Id full_definition = Declaration_Node (gnat_entity);
        Node_Id record_definition = Type_Definition (full_definition);
        Entity_Id gnat_field;
        tree gnu_field;
        tree gnu_field_list = NULL_TREE;
        tree gnu_get_parent;
        /* Set PACKED in keeping with gnat_to_gnu_field.  */
        int packed
          = Is_Packed (gnat_entity)
            ? 1
            : Component_Alignment (gnat_entity) == Calign_Storage_Unit
              ? -1
              : (Known_Alignment (gnat_entity)
                 || (Strict_Alignment (gnat_entity)
                     && Known_Static_Esize (gnat_entity)))
                ? -2
                : 0;
        bool has_rep = Has_Specified_Layout (gnat_entity);
        bool all_rep = has_rep;
        bool is_extension
          = (Is_Tagged_Type (gnat_entity)
             && Nkind (record_definition) == N_Derived_Type_Definition);

        /* See if all fields have a rep clause.  Stop when we find one
           that doesn't.  */
        for (gnat_field = First_Entity (gnat_entity);
             Present (gnat_field) && all_rep;
             gnat_field = Next_Entity (gnat_field))
          if ((Ekind (gnat_field) == E_Component
               || Ekind (gnat_field) == E_Discriminant)
              && No (Component_Clause (gnat_field)))
            all_rep = false;

        /* If this is a record extension, go a level further to find the
           record definition.  Also, verify we have a Parent_Subtype.  */
        if (is_extension)
          {
            if (!type_annotate_only
                || Present (Record_Extension_Part (record_definition)))
              record_definition = Record_Extension_Part (record_definition);

            gcc_assert (type_annotate_only
                        || Present (Parent_Subtype (gnat_entity)));
          }

        /* Make a node for the record.  If we are not defining the record,
           suppress expanding incomplete types.  */
        gnu_type = make_node (tree_code_for_record_type (gnat_entity));
        TYPE_NAME (gnu_type) = gnu_entity_id;
        TYPE_PACKED (gnu_type) = (packed != 0) || has_rep;

        if (!definition)
          defer_incomplete_level++, this_deferred = true;

        /* If both a size and rep clause was specified, put the size in
           the record type now so that it can get the proper mode.  */
        if (has_rep && Known_Esize (gnat_entity))
          TYPE_SIZE (gnu_type) = UI_To_gnu (Esize (gnat_entity), sizetype);

        /* Always set the alignment here so that it can be used to
           set the mode, if it is making the alignment stricter.  If
           it is invalid, it will be checked again below.  If this is to
           be Atomic, choose a default alignment of a word unless we know
           the size and it's smaller.  */
        if (Known_Alignment (gnat_entity))
          TYPE_ALIGN (gnu_type)
            = validate_alignment (Alignment (gnat_entity), gnat_entity, 0);
        else if (Is_Atomic (gnat_entity))
          TYPE_ALIGN (gnu_type)
            = esize >= BITS_PER_WORD ? BITS_PER_WORD : ceil_alignment (esize);
        /* If a type needs strict alignment, the minimum size will be the
           type size instead of the RM size (see validate_size).  Cap the
           alignment, lest it causes this type size to become too large.  */
        else if (Strict_Alignment (gnat_entity)
                 && Known_Static_Esize (gnat_entity))
          {
            unsigned int raw_size = UI_To_Int (Esize (gnat_entity));
            unsigned int raw_align = raw_size & -raw_size;
            if (raw_align < BIGGEST_ALIGNMENT)
              TYPE_ALIGN (gnu_type) = raw_align;
          }
        else
          TYPE_ALIGN (gnu_type) = 0;

        /* If we have a Parent_Subtype, make a field for the parent.  If
           this record has rep clauses, force the position to zero.  */
        if (Present (Parent_Subtype (gnat_entity)))
          {
            Entity_Id gnat_parent = Parent_Subtype (gnat_entity);
            tree gnu_parent;

            /* A major complexity here is that the parent subtype will
               reference our discriminants in its Discriminant_Constraint
               list.  But those must reference the parent component of this
               record which is of the parent subtype we have not built yet!
               To break the circle we first build a dummy COMPONENT_REF which
               represents the "get to the parent" operation and initialize
               each of those discriminants to a COMPONENT_REF of the above
               dummy parent referencing the corresponding discriminant of the
               base type of the parent subtype.  */
            gnu_get_parent = build3 (COMPONENT_REF, void_type_node,
                                     build0 (PLACEHOLDER_EXPR, gnu_type),
                                     build_decl (FIELD_DECL, NULL_TREE,
                                                 void_type_node),
                                     NULL_TREE);

            if (Has_Discriminants (gnat_entity))
              for (gnat_field = First_Stored_Discriminant (gnat_entity);
                   Present (gnat_field);
                   gnat_field = Next_Stored_Discriminant (gnat_field))
                if (Present (Corresponding_Discriminant (gnat_field)))
                  save_gnu_tree
                    (gnat_field,
                     build3 (COMPONENT_REF,
                             get_unpadded_type (Etype (gnat_field)),
                             gnu_get_parent,
                             gnat_to_gnu_field_decl (Corresponding_Discriminant
                                                     (gnat_field)),
                             NULL_TREE),
                     true);

            /* Then we build the parent subtype.  */
            gnu_parent = gnat_to_gnu_type (gnat_parent);

            /* Finally we fix up both kinds of twisted COMPONENT_REF we have
               initially built.  The discriminants must reference the fields
               of the parent subtype and not those of its base type for the
               placeholder machinery to properly work.  */
            if (Has_Discriminants (gnat_entity))
              for (gnat_field = First_Stored_Discriminant (gnat_entity);
                   Present (gnat_field);
                   gnat_field = Next_Stored_Discriminant (gnat_field))
                if (Present (Corresponding_Discriminant (gnat_field)))
                  {
                    Entity_Id field = Empty;
                    for (field = First_Stored_Discriminant (gnat_parent);
                         Present (field);
                         field = Next_Stored_Discriminant (field))
                      if (same_discriminant_p (gnat_field, field))
                        break;
                    gcc_assert (Present (field));
                    TREE_OPERAND (get_gnu_tree (gnat_field), 1)
                      = gnat_to_gnu_field_decl (field);
                  }

            /* The "get to the parent" COMPONENT_REF must be given its
               proper type...  */
            TREE_TYPE (gnu_get_parent) = gnu_parent;

            /* ...and reference the _parent field of this record.  */
            gnu_field_list
              = create_field_decl (get_identifier
                                   (Get_Name_String (Name_uParent)),
                                   gnu_parent, gnu_type, 0,
                                   has_rep ? TYPE_SIZE (gnu_parent) : 0,
                                   has_rep ? bitsize_zero_node : 0, 1);
            DECL_INTERNAL_P (gnu_field_list) = 1;
            TREE_OPERAND (gnu_get_parent, 1) = gnu_field_list;
          }

        /* Make the fields for the discriminants and put them into the record
           unless it's an Unchecked_Union.  */
        if (Has_Discriminants (gnat_entity))
          for (gnat_field = First_Stored_Discriminant (gnat_entity);
               Present (gnat_field);
               gnat_field = Next_Stored_Discriminant (gnat_field))
            {
              /* If this is a record extension and this discriminant
                 is the renaming of another discriminant, we've already
                 handled the discriminant above.  */
              if (Present (Parent_Subtype (gnat_entity))
                  && Present (Corresponding_Discriminant (gnat_field)))
                continue;

              gnu_field
                = gnat_to_gnu_field (gnat_field, gnu_type, packed, definition);

              /* Make an expression using a PLACEHOLDER_EXPR from the
                 FIELD_DECL node just created and link that with the
                 corresponding GNAT defining identifier.  Then add to the
                 list of fields.  */
              save_gnu_tree (gnat_field,
                             build3 (COMPONENT_REF, TREE_TYPE (gnu_field),
                                     build0 (PLACEHOLDER_EXPR,
                                             DECL_CONTEXT (gnu_field)),
                                     gnu_field, NULL_TREE),
                             true);

              if (!Is_Unchecked_Union (gnat_entity))
                {
                  TREE_CHAIN (gnu_field) = gnu_field_list;
                  gnu_field_list = gnu_field;
                }
            }

        /* Put the discriminants into the record (backwards), so we can
           know the appropriate discriminant to use for the names of the
           variants.  */
        TYPE_FIELDS (gnu_type) = gnu_field_list;

        /* Add the listed fields into the record and finish it up.  */
        components_to_record (gnu_type, Component_List (record_definition),
                              gnu_field_list, packed, definition, NULL,
                              false, all_rep, false,
                              Is_Unchecked_Union (gnat_entity));

        /* We used to remove the associations of the discriminants and
           _Parent for validity checking, but we may need them if there's
           Freeze_Node for a subtype used in this record.  */
        TYPE_VOLATILE (gnu_type) = Treat_As_Volatile (gnat_entity);
        TYPE_BY_REFERENCE_P (gnu_type) = Is_By_Reference_Type (gnat_entity);

        /* If it is a tagged record force the type to BLKmode to insure
           that these objects will always be placed in memory.  Do the
           same thing for limited record types.  */
        if (Is_Tagged_Type (gnat_entity) || Is_Limited_Record (gnat_entity))
          SET_TYPE_MODE (gnu_type, BLKmode);

        /* Fill in locations of fields.  */
        annotate_rep (gnat_entity, gnu_type);

        /* If there are any entities in the chain corresponding to
           components that we did not elaborate, ensure we elaborate their
           types if they are Itypes.  */
        for (gnat_temp = First_Entity (gnat_entity);
             Present (gnat_temp); gnat_temp = Next_Entity (gnat_temp))
          if ((Ekind (gnat_temp) == E_Component
               || Ekind (gnat_temp) == E_Discriminant)
              && Is_Itype (Etype (gnat_temp))
              && !present_gnu_tree (gnat_temp))
            gnat_to_gnu_entity (Etype (gnat_temp), NULL_TREE, 0);
      }
      break;

    case E_Class_Wide_Subtype:
      /* If an equivalent type is present, that is what we should use.
         Otherwise, fall through to handle this like a record subtype
         since it may have constraints.  */
      if (gnat_equiv_type != gnat_entity)
        {
          gnu_decl = gnat_to_gnu_entity (gnat_equiv_type, NULL_TREE, 0);
          maybe_present = true;
          break;
        }

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

    case E_Record_Subtype:

      /* If Cloned_Subtype is Present it means this record subtype has
         identical layout to that type or subtype and we should use
         that GCC type for this one.  The front end guarantees that
         the component list is shared.  */
      if (Present (Cloned_Subtype (gnat_entity)))
        {
          gnu_decl = gnat_to_gnu_entity (Cloned_Subtype (gnat_entity),
                                         NULL_TREE, 0);
          maybe_present = true;
        }

      /* Otherwise, first ensure the base type is elaborated.  Then, if we are
         changing the type, make a new type with each field having the
         type of the field in the new subtype but having the position
         computed by transforming every discriminant reference according
         to the constraints.  We don't see any difference between
         private and nonprivate type here since derivations from types should
         have been deferred until the completion of the private type.  */
      else
        {
          Entity_Id gnat_base_type = Implementation_Base_Type (gnat_entity);
          tree gnu_base_type;
          tree gnu_orig_type;

          if (!definition)
            defer_incomplete_level++, this_deferred = true;

          /* Get the base type initially for its alignment and sizes.  But
             if it is a padded type, we do all the other work with the
             unpadded type.  */
          gnu_base_type = gnat_to_gnu_type (gnat_base_type);

          if (TREE_CODE (gnu_base_type) == RECORD_TYPE
              && TYPE_IS_PADDING_P (gnu_base_type))
            gnu_type = gnu_orig_type = TREE_TYPE (TYPE_FIELDS (gnu_base_type));
          else
            gnu_type = gnu_orig_type = gnu_base_type;

          if (present_gnu_tree (gnat_entity))
            {
              maybe_present = true;
              break;
            }

          /* When the type has discriminants, and these discriminants
             affect the shape of what it built, factor them in.

             If we are making a subtype of an Unchecked_Union (must be an
             Itype), just return the type.

             We can't just use Is_Constrained because private subtypes without
             discriminants of full types with discriminants with default
             expressions are Is_Constrained but aren't constrained!  */

          if (IN (Ekind (gnat_base_type), Record_Kind)
              && !Is_For_Access_Subtype (gnat_entity)
              && !Is_Unchecked_Union (gnat_base_type)
              && Is_Constrained (gnat_entity)
              && Stored_Constraint (gnat_entity) != No_Elist
              && Present (Discriminant_Constraint (gnat_entity)))
            {
              Entity_Id gnat_field;
              tree gnu_field_list = 0;
              tree gnu_pos_list
                = compute_field_positions (gnu_orig_type, NULL_TREE,
                                           size_zero_node, bitsize_zero_node,
                                           BIGGEST_ALIGNMENT);
              tree gnu_subst_list
                = substitution_list (gnat_entity, gnat_base_type, NULL_TREE,
                                     definition);
              tree gnu_temp;

              gnu_type = make_node (RECORD_TYPE);
              TYPE_NAME (gnu_type) = gnu_entity_id;
              TYPE_VOLATILE (gnu_type) = Treat_As_Volatile (gnat_entity);

              /* Set the size, alignment and alias set of the new type to
                 match that of the old one, doing required substitutions.
                 We do it this early because we need the size of the new
                 type below to discard old fields if necessary.  */
              TYPE_SIZE (gnu_type) = TYPE_SIZE (gnu_base_type);
              TYPE_SIZE_UNIT (gnu_type) = TYPE_SIZE_UNIT (gnu_base_type);
              SET_TYPE_ADA_SIZE (gnu_type, TYPE_ADA_SIZE (gnu_base_type));
              TYPE_ALIGN (gnu_type) = TYPE_ALIGN (gnu_base_type);
              relate_alias_sets (gnu_type, gnu_base_type, ALIAS_SET_COPY);

              if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type)))
                for (gnu_temp = gnu_subst_list;
                     gnu_temp; gnu_temp = TREE_CHAIN (gnu_temp))
                  TYPE_SIZE (gnu_type)
                    = substitute_in_expr (TYPE_SIZE (gnu_type),
                                          TREE_PURPOSE (gnu_temp),
                                          TREE_VALUE (gnu_temp));

              if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE_UNIT (gnu_type)))
                for (gnu_temp = gnu_subst_list;
                     gnu_temp; gnu_temp = TREE_CHAIN (gnu_temp))
                  TYPE_SIZE_UNIT (gnu_type)
                    = substitute_in_expr (TYPE_SIZE_UNIT (gnu_type),
                                          TREE_PURPOSE (gnu_temp),
                                          TREE_VALUE (gnu_temp));

              if (CONTAINS_PLACEHOLDER_P (TYPE_ADA_SIZE (gnu_type)))
                for (gnu_temp = gnu_subst_list;
                     gnu_temp; gnu_temp = TREE_CHAIN (gnu_temp))
                  SET_TYPE_ADA_SIZE
                    (gnu_type, substitute_in_expr (TYPE_ADA_SIZE (gnu_type),
                                                   TREE_PURPOSE (gnu_temp),
                                                   TREE_VALUE (gnu_temp)));

              for (gnat_field = First_Entity (gnat_entity);
                   Present (gnat_field); gnat_field = Next_Entity (gnat_field))
                if ((Ekind (gnat_field) == E_Component
                     || Ekind (gnat_field) == E_Discriminant)
                    && (Underlying_Type (Scope (Original_Record_Component
                                                (gnat_field)))
                        == gnat_base_type)
                    && (No (Corresponding_Discriminant (gnat_field))
                        || !Is_Tagged_Type (gnat_base_type)))
                  {
                    tree gnu_old_field
                      = gnat_to_gnu_field_decl (Original_Record_Component
                                                (gnat_field));
                    tree gnu_offset
                      = TREE_VALUE (purpose_member (gnu_old_field,
                                                    gnu_pos_list));
                    tree gnu_pos = TREE_PURPOSE (gnu_offset);
                    tree gnu_bitpos = TREE_VALUE (TREE_VALUE (gnu_offset));
                    tree gnu_field_type
                      = gnat_to_gnu_type (Etype (gnat_field));
                    tree gnu_size = TYPE_SIZE (gnu_field_type);
                    tree gnu_new_pos = NULL_TREE;
                    unsigned int offset_align
                      = tree_low_cst (TREE_PURPOSE (TREE_VALUE (gnu_offset)),
                                      1);
                    tree gnu_field;

                    /* If there was a component clause, the field types must be
                       the same for the type and subtype, so copy the data from
                       the old field to avoid recomputation here.  Also if the
                       field is justified modular and the optimization in
                       gnat_to_gnu_field was applied.  */
                    if (Present (Component_Clause
                                 (Original_Record_Component (gnat_field)))
                        || (TREE_CODE (gnu_field_type) == RECORD_TYPE
                            && TYPE_JUSTIFIED_MODULAR_P (gnu_field_type)
                            && TREE_TYPE (TYPE_FIELDS (gnu_field_type))
                               == TREE_TYPE (gnu_old_field)))
                      {
                        gnu_size = DECL_SIZE (gnu_old_field);
                        gnu_field_type = TREE_TYPE (gnu_old_field);
                      }

                    /* If the old field was packed and of constant size, we
                       have to get the old size here, as it might differ from
                       what the Etype conveys and the latter might overlap
                       onto the following field.  Try to arrange the type for
                       possible better packing along the way.  */
                    else if (DECL_PACKED (gnu_old_field)
                             && TREE_CODE (DECL_SIZE (gnu_old_field))
                                == INTEGER_CST)
                      {
                        gnu_size = DECL_SIZE (gnu_old_field);
                        if (TREE_CODE (gnu_field_type) == RECORD_TYPE
                            && !TYPE_IS_FAT_POINTER_P (gnu_field_type)
                            && host_integerp (TYPE_SIZE (gnu_field_type), 1))
                          gnu_field_type
                            = make_packable_type (gnu_field_type, true);
                      }

                    if (CONTAINS_PLACEHOLDER_P (gnu_pos))
                      for (gnu_temp = gnu_subst_list;
                           gnu_temp; gnu_temp = TREE_CHAIN (gnu_temp))
                        gnu_pos = substitute_in_expr (gnu_pos,
                                                      TREE_PURPOSE (gnu_temp),
                                                      TREE_VALUE (gnu_temp));

                    /* If the position is now a constant, we can set it as the
                       position of the field when we make it.  Otherwise, we need
                       to deal with it specially below.  */
                    if (TREE_CONSTANT (gnu_pos))
                      {
                        gnu_new_pos = bit_from_pos (gnu_pos, gnu_bitpos);

                        /* Discard old fields that are outside the new type.
                           This avoids confusing code scanning it to decide
                           how to pass it to functions on some platforms.  */
                        if (TREE_CODE (gnu_new_pos) == INTEGER_CST
                            && TREE_CODE (TYPE_SIZE (gnu_type)) == INTEGER_CST
                            && !integer_zerop (gnu_size)
                            && !tree_int_cst_lt (gnu_new_pos,
                                                 TYPE_SIZE (gnu_type)))
                          continue;
                      }

                    gnu_field
                      = create_field_decl
                        (DECL_NAME (gnu_old_field), gnu_field_type, gnu_type,
                         DECL_PACKED (gnu_old_field), gnu_size, gnu_new_pos,
                         !DECL_NONADDRESSABLE_P (gnu_old_field));

                    if (!TREE_CONSTANT (gnu_pos))
                      {
                        normalize_offset (&gnu_pos, &gnu_bitpos, offset_align);
                        DECL_FIELD_OFFSET (gnu_field) = gnu_pos;
                        DECL_FIELD_BIT_OFFSET (gnu_field) = gnu_bitpos;
                        SET_DECL_OFFSET_ALIGN (gnu_field, offset_align);
                        DECL_SIZE (gnu_field) = gnu_size;
                        DECL_SIZE_UNIT (gnu_field)
                          = convert (sizetype,
                                     size_binop (CEIL_DIV_EXPR, gnu_size,
                                                 bitsize_unit_node));
                        layout_decl (gnu_field, DECL_OFFSET_ALIGN (gnu_field));
                      }

                    DECL_INTERNAL_P (gnu_field)
                      = DECL_INTERNAL_P (gnu_old_field);
                    SET_DECL_ORIGINAL_FIELD
                      (gnu_field, (DECL_ORIGINAL_FIELD (gnu_old_field)
                                   ? DECL_ORIGINAL_FIELD (gnu_old_field)
                                   : gnu_old_field));
                    DECL_DISCRIMINANT_NUMBER (gnu_field)
                      = DECL_DISCRIMINANT_NUMBER (gnu_old_field);
                    TREE_THIS_VOLATILE (gnu_field)
                      = TREE_THIS_VOLATILE (gnu_old_field);

                    /* To match the layout crafted in components_to_record, if
                       this is the _Tag field, put it before any discriminants
                       instead of after them as for all other fields.  */
                    if (Chars (gnat_field) == Name_uTag)
                      gnu_field_list = chainon (gnu_field_list, gnu_field);
                    else
                      {
                        TREE_CHAIN (gnu_field) = gnu_field_list;
                        gnu_field_list = gnu_field;
                      }

                    save_gnu_tree (gnat_field, gnu_field, false);
                  }

              /* Now go through the entities again looking for Itypes that
                 we have not elaborated but should (e.g., Etypes of fields
                 that have Original_Components).  */
              for (gnat_field = First_Entity (gnat_entity);
                   Present (gnat_field); gnat_field = Next_Entity (gnat_field))
                if ((Ekind (gnat_field) == E_Discriminant
                     || Ekind (gnat_field) == E_Component)
                    && !present_gnu_tree (Etype (gnat_field)))
                  gnat_to_gnu_entity (Etype (gnat_field), NULL_TREE, 0);

              /* Do not finalize it since we're going to modify it below.  */
              gnu_field_list = nreverse (gnu_field_list);
              finish_record_type (gnu_type, gnu_field_list, 2, true);

              /* Finalize size and mode.  */
              TYPE_SIZE (gnu_type) = variable_size (TYPE_SIZE (gnu_type));
              TYPE_SIZE_UNIT (gnu_type)
                = variable_size (TYPE_SIZE_UNIT (gnu_type));

              compute_record_mode (gnu_type);

              /* Fill in locations of fields.  */
              annotate_rep (gnat_entity, gnu_type);

              /* We've built a new type, make an XVS type to show what this
                 is a subtype of.  Some debuggers require the XVS type to be
                 output first, so do it in that order.  */
              if (debug_info_p)
                {
                  tree gnu_subtype_marker = make_node (RECORD_TYPE);
                  tree gnu_orig_name = TYPE_NAME (gnu_orig_type);

                  if (TREE_CODE (gnu_orig_name) == TYPE_DECL)
                    gnu_orig_name = DECL_NAME (gnu_orig_name);

                  TYPE_NAME (gnu_subtype_marker)
                    = create_concat_name (gnat_entity, "XVS");
                  finish_record_type (gnu_subtype_marker,
                                      create_field_decl (gnu_orig_name,
                                                         integer_type_node,
                                                         gnu_subtype_marker,
                                                         0, NULL_TREE,
                                                         NULL_TREE, 0),
                                      0, false);

                  add_parallel_type (TYPE_STUB_DECL (gnu_type),
                                     gnu_subtype_marker);
                }

              /* Now we can finalize it.  */
              rest_of_record_type_compilation (gnu_type);
            }

          /* Otherwise, go down all the components in the new type and
             make them equivalent to those in the base type.  */
          else
            for (gnat_temp = First_Entity (gnat_entity); Present (gnat_temp);
                 gnat_temp = Next_Entity (gnat_temp))
              if ((Ekind (gnat_temp) == E_Discriminant
                   && !Is_Unchecked_Union (gnat_base_type))
                  || Ekind (gnat_temp) == E_Component)
                save_gnu_tree (gnat_temp,
                               gnat_to_gnu_field_decl
                               (Original_Record_Component (gnat_temp)), false);
        }
      break;

    case E_Access_Subprogram_Type:
      /* Use the special descriptor type for dispatch tables if needed,
         that is to say for the Prim_Ptr of a-tags.ads and its clones.
         Note that we are only required to do so for static tables in
         order to be compatible with the C++ ABI, but Ada 2005 allows
         to extend library level tagged types at the local level so
         we do it in the non-static case as well.  */
      if (TARGET_VTABLE_USES_DESCRIPTORS
          && Is_Dispatch_Table_Entity (gnat_entity))
        {
            gnu_type = fdesc_type_node;
            gnu_size = TYPE_SIZE (gnu_type);
            break;
        }

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

    case E_Anonymous_Access_Subprogram_Type:
      /* If we are not defining this entity, and we have incomplete
         entities being processed above us, make a dummy type and
         fill it in later.  */
      if (!definition && defer_incomplete_level != 0)
        {
          struct incomplete *p
            = (struct incomplete *) xmalloc (sizeof (struct incomplete));

          gnu_type
            = build_pointer_type
              (make_dummy_type (Directly_Designated_Type (gnat_entity)));
          gnu_decl = create_type_decl (gnu_entity_id, gnu_type, attr_list,
                                       !Comes_From_Source (gnat_entity),
                                       debug_info_p, gnat_entity);
          this_made_decl = true;
          gnu_type = TREE_TYPE (gnu_decl);
          save_gnu_tree (gnat_entity, gnu_decl, false);
          saved = true;

          p->old_type = TREE_TYPE (gnu_type);
          p->full_type = Directly_Designated_Type (gnat_entity);
          p->next = defer_incomplete_list;
          defer_incomplete_list = p;
          break;
        }

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

    case E_Allocator_Type:
    case E_Access_Type:
    case E_Access_Attribute_Type:
    case E_Anonymous_Access_Type:
    case E_General_Access_Type:
      {
        Entity_Id gnat_desig_type = Directly_Designated_Type (gnat_entity);
        Entity_Id gnat_desig_equiv = Gigi_Equivalent_Type (gnat_desig_type);
        bool is_from_limited_with
          = (IN (Ekind (gnat_desig_equiv), Incomplete_Kind)
             && From_With_Type (gnat_desig_equiv));

        /* Get the "full view" of this entity.  If this is an incomplete
           entity from a limited with, treat its non-limited view as the full
           view.  Otherwise, if this is an incomplete or private type, use the
           full view.  In the former case, we might point to a private type,
           in which case, we need its full view.  Also, we want to look at the
           actual type used for the representation, so this takes a total of
           three steps.  */
        Entity_Id gnat_desig_full_direct_first
          = (is_from_limited_with ? Non_Limited_View (gnat_desig_equiv)
             : (IN (Ekind (gnat_desig_equiv), Incomplete_Or_Private_Kind)
                ? Full_View (gnat_desig_equiv) : Empty));
        Entity_Id gnat_desig_full_direct
          = ((is_from_limited_with
              && Present (gnat_desig_full_direct_first)
              && IN (Ekind (gnat_desig_full_direct_first), Private_Kind))
             ? Full_View (gnat_desig_full_direct_first)
             : gnat_desig_full_direct_first);
        Entity_Id gnat_desig_full
          = Gigi_Equivalent_Type (gnat_desig_full_direct);

        /* This the type actually used to represent the designated type,
           either gnat_desig_full or gnat_desig_equiv.  */
        Entity_Id gnat_desig_rep;

        /* True if this is a pointer to an unconstrained array.  */
        bool is_unconstrained_array;

        /* We want to know if we'll be seeing the freeze node for any
           incomplete type we may be pointing to.  */
        bool in_main_unit
          = (Present (gnat_desig_full)
             ? In_Extended_Main_Code_Unit (gnat_desig_full)
             : In_Extended_Main_Code_Unit (gnat_desig_type));

        /* True if we make a dummy type here.  */
        bool got_fat_p = false;
        /* True if the dummy is a fat pointer.  */
        bool made_dummy = false;
        tree gnu_desig_type = NULL_TREE;
        enum machine_mode p_mode = mode_for_size (esize, MODE_INT, 0);

        if (!targetm.valid_pointer_mode (p_mode))
          p_mode = ptr_mode;

        /* If either the designated type or its full view is an unconstrained
           array subtype, replace it with the type it's a subtype of.  This
           avoids problems with multiple copies of unconstrained array types.
           Likewise, if the designated type is a subtype of an incomplete
           record type, use the parent type to avoid order of elaboration
           issues.  This can lose some code efficiency, but there is no
           alternative.  */
        if (Ekind (gnat_desig_equiv) == E_Array_Subtype
            && ! Is_Constrained (gnat_desig_equiv))
          gnat_desig_equiv = Etype (gnat_desig_equiv);
        if (Present (gnat_desig_full)
            && ((Ekind (gnat_desig_full) == E_Array_Subtype
                 && ! Is_Constrained (gnat_desig_full))
                || (Ekind (gnat_desig_full) == E_Record_Subtype
                    && Ekind (Etype (gnat_desig_full)) == E_Record_Type)))
          gnat_desig_full = Etype (gnat_desig_full);

        /* Now set the type that actually marks the representation of
           the designated type and also flag whether we have a unconstrained
           array.  */
        gnat_desig_rep = gnat_desig_full ? gnat_desig_full : gnat_desig_equiv;
        is_unconstrained_array
          = (Is_Array_Type (gnat_desig_rep)
             && ! Is_Constrained (gnat_desig_rep));

        /* If we are pointing to an incomplete type whose completion is an
           unconstrained array, make a fat pointer type.  The two types in our
           fields will be pointers to dummy nodes and will be replaced in
           update_pointer_to.  Similarly, if the type itself is a dummy type or
           an unconstrained array.  Also make a dummy TYPE_OBJECT_RECORD_TYPE
           in case we have any thin pointers to it.  */
        if (is_unconstrained_array
            && (Present (gnat_desig_full)
                || (present_gnu_tree (gnat_desig_equiv)
                    && TYPE_IS_DUMMY_P (TREE_TYPE
                                        (get_gnu_tree (gnat_desig_equiv))))
                || (No (gnat_desig_full) && ! in_main_unit
                    && defer_incomplete_level != 0
                    && ! present_gnu_tree (gnat_desig_equiv))
                || (in_main_unit && is_from_limited_with
                    && Present (Freeze_Node (gnat_desig_rep)))))
          {
            tree gnu_old
              = (present_gnu_tree (gnat_desig_rep)
                 ? TREE_TYPE (get_gnu_tree (gnat_desig_rep))
                 : make_dummy_type (gnat_desig_rep));
            tree fields;

            /* Show the dummy we get will be a fat pointer.  */
            got_fat_p = made_dummy = true;

            /* If the call above got something that has a pointer, that
               pointer is our type.  This could have happened either
               because the type was elaborated or because somebody
               else executed the code below.  */
            gnu_type = TYPE_POINTER_TO (gnu_old);
            if (!gnu_type)
              {
                tree gnu_template_type = make_node (ENUMERAL_TYPE);
                tree gnu_ptr_template = build_pointer_type (gnu_template_type);
                tree gnu_array_type = make_node (ENUMERAL_TYPE);
                tree gnu_ptr_array = build_pointer_type (gnu_array_type);

                TYPE_NAME (gnu_template_type)
                  = concat_id_with_name (get_entity_name (gnat_desig_equiv),
                                         "XUB");
                TYPE_DUMMY_P (gnu_template_type) = 1;

                TYPE_NAME (gnu_array_type)
                  = concat_id_with_name (get_entity_name (gnat_desig_equiv),
                                         "XUA");
                TYPE_DUMMY_P (gnu_array_type) = 1;

                gnu_type = make_node (RECORD_TYPE);
                SET_TYPE_UNCONSTRAINED_ARRAY (gnu_type, gnu_old);
                TYPE_POINTER_TO (gnu_old) = gnu_type;

                Sloc_to_locus (Sloc (gnat_entity), &input_location);
                fields
                  = chainon (chainon (NULL_TREE,
                                      create_field_decl
                                      (get_identifier ("P_ARRAY"),
                                       gnu_ptr_array,
                                       gnu_type, 0, 0, 0, 0)),
                             create_field_decl (get_identifier ("P_BOUNDS"),
                                                gnu_ptr_template,
                                                gnu_type, 0, 0, 0, 0));

                /* Make sure we can place this into a register.  */
                TYPE_ALIGN (gnu_type)
                  = MIN (BIGGEST_ALIGNMENT, 2 * POINTER_SIZE);
                TYPE_IS_FAT_POINTER_P (gnu_type) = 1;

                /* Do not finalize this record type since the types of
                   its fields are incomplete.  */
                finish_record_type (gnu_type, fields, 0, true);

                TYPE_OBJECT_RECORD_TYPE (gnu_old) = make_node (RECORD_TYPE);
                TYPE_NAME (TYPE_OBJECT_RECORD_TYPE (gnu_old))
                  = concat_id_with_name (get_entity_name (gnat_desig_equiv),
                                         "XUT");
                TYPE_DUMMY_P (TYPE_OBJECT_RECORD_TYPE (gnu_old)) = 1;
              }
          }

        /* If we already know what the full type is, use it.  */
        else if (Present (gnat_desig_full)
                 && present_gnu_tree (gnat_desig_full))
          gnu_desig_type = TREE_TYPE (get_gnu_tree (gnat_desig_full));

        /* Get the type of the thing we are to point to and build a pointer
           to it.  If it is a reference to an incomplete or private type with a
           full view that is a record, make a dummy type node and get the
           actual type later when we have verified it is safe.  */
        else if ((! in_main_unit
                  && ! present_gnu_tree (gnat_desig_equiv)
                  && Present (gnat_desig_full)
                  && ! present_gnu_tree (gnat_desig_full)
                  && Is_Record_Type (gnat_desig_full))
                 /* Likewise if we are pointing to a record or array and we
                    are to defer elaborating incomplete types.  We do this
                    since this access type may be the full view of some
                    private type.  Note that the unconstrained array case is
                    handled above.  */
                 || ((! in_main_unit || imported_p)
                     && defer_incomplete_level != 0
                     && ! present_gnu_tree (gnat_desig_equiv)
                     && ((Is_Record_Type (gnat_desig_rep)
                          || Is_Array_Type (gnat_desig_rep))))
                 /* If this is a reference from a limited_with type back to our
                    main unit and there's a Freeze_Node for it, either we have
                    already processed the declaration and made the dummy type,
                    in which case we just reuse the latter, or we have not yet,
                    in which case we make the dummy type and it will be reused
                    when the declaration is processed.  In both cases, the
                    pointer eventually created below will be automatically
                    adjusted when the Freeze_Node is processed.  Note that the
                    unconstrained array case is handled above.  */
                 ||  (in_main_unit && is_from_limited_with
                      && Present (Freeze_Node (gnat_desig_rep))))
          {
            gnu_desig_type = make_dummy_type (gnat_desig_equiv);
            made_dummy = true;
          }

        /* Otherwise handle the case of a pointer to itself.  */
        else if (gnat_desig_equiv == gnat_entity)
          {
            gnu_type
              = build_pointer_type_for_mode (void_type_node, p_mode,
                                             No_Strict_Aliasing (gnat_entity));
            TREE_TYPE (gnu_type) = TYPE_POINTER_TO (gnu_type) = gnu_type;
          }

        /* If expansion is disabled, the equivalent type of a concurrent
           type is absent, so build a dummy pointer type.  */
        else if (type_annotate_only && No (gnat_desig_equiv))
          gnu_type = ptr_void_type_node;

        /* Finally, handle the straightforward case where we can just
           elaborate our designated type and point to it.  */
        else
          gnu_desig_type = gnat_to_gnu_type (gnat_desig_equiv);

        /* It is possible that a call to gnat_to_gnu_type above resolved our
           type.  If so, just return it.  */
        if (present_gnu_tree (gnat_entity))
          {
            maybe_present = true;
            break;
          }

        /* If we have a GCC type for the designated type, possibly modify it
           if we are pointing only to constant objects and then make a pointer
           to it.  Don't do this for unconstrained arrays.  */
        if (!gnu_type && gnu_desig_type)
          {
            if (Is_Access_Constant (gnat_entity)
                && TREE_CODE (gnu_desig_type) != UNCONSTRAINED_ARRAY_TYPE)
              {
                gnu_desig_type
                  = build_qualified_type
                    (gnu_desig_type,
                     TYPE_QUALS (gnu_desig_type) | TYPE_QUAL_CONST);

                /* Some extra processing is required if we are building a
                   pointer to an incomplete type (in the GCC sense).  We might
                   have such a type if we just made a dummy, or directly out
                   of the call to gnat_to_gnu_type above if we are processing
                   an access type for a record component designating the
                   record type itself.  */
                if (TYPE_MODE (gnu_desig_type) == VOIDmode)
                  {
                    /* We must ensure that the pointer to variant we make will
                       be processed by update_pointer_to when the initial type
                       is completed.  Pretend we made a dummy and let further
                       processing act as usual.  */
                    made_dummy = true;

                    /* We must ensure that update_pointer_to will not retrieve
                       the dummy variant when building a properly qualified
                       version of the complete type.  We take advantage of the
                       fact that get_qualified_type is requiring TYPE_NAMEs to
                       match to influence build_qualified_type and then also
                       update_pointer_to here.  */
                    TYPE_NAME (gnu_desig_type)
                      = create_concat_name (gnat_desig_type, "INCOMPLETE_CST");
                  }
              }

            gnu_type
              = build_pointer_type_for_mode (gnu_desig_type, p_mode,
                                             No_Strict_Aliasing (gnat_entity));
          }

        /* If we are not defining this object and we made a dummy pointer,
           save our current definition, evaluate the actual type, and replace
           the tentative type we made with the actual one.  If we are to defer
           actually looking up the actual type, make an entry in the
           deferred list.  If this is from a limited with, we have to defer
           to the end of the current spec in two cases: first if the
           designated type is in the current unit and second if the access
           type is.  */
        if ((! in_main_unit || is_from_limited_with) && made_dummy)
          {
            tree gnu_old_type
              = TYPE_FAT_POINTER_P (gnu_type)
                ? TYPE_UNCONSTRAINED_ARRAY (gnu_type) : TREE_TYPE (gnu_type);

            if (esize == POINTER_SIZE
                && (got_fat_p || TYPE_FAT_POINTER_P (gnu_type)))
              gnu_type
                = build_pointer_type
                  (TYPE_OBJECT_RECORD_TYPE
                   (TYPE_UNCONSTRAINED_ARRAY (gnu_type)));

            gnu_decl = create_type_decl (gnu_entity_id, gnu_type, attr_list,
                                         !Comes_From_Source (gnat_entity),
                                         debug_info_p, gnat_entity);
            this_made_decl = true;
            gnu_type = TREE_TYPE (gnu_decl);
            save_gnu_tree (gnat_entity, gnu_decl, false);
            saved = true;

            if (defer_incomplete_level == 0
                && ! (is_from_limited_with
                      && (in_main_unit
                          || In_Extended_Main_Code_Unit (gnat_entity))))
              update_pointer_to (TYPE_MAIN_VARIANT (gnu_old_type),
                                 gnat_to_gnu_type (gnat_desig_equiv));

              /* Note that the call to gnat_to_gnu_type here might have
                 updated gnu_old_type directly, in which case it is not a
                 dummy type any more when we get into update_pointer_to.

                 This may happen for instance when the designated type is a
                 record type, because their elaboration starts with an
                 initial node from make_dummy_type, which may yield the same
                 node as the one we got.

                 Besides, variants of this non-dummy type might have been
                 created along the way.  update_pointer_to is expected to
                 properly take care of those situations.  */
            else
              {
                struct incomplete *p
                  = (struct incomplete *) xmalloc (sizeof
                                                   (struct incomplete));
                struct incomplete **head
                  = (is_from_limited_with
                     && (in_main_unit
                         || In_Extended_Main_Code_Unit (gnat_entity))
                     ? &defer_limited_with : &defer_incomplete_list);

                p->old_type = gnu_old_type;
                p->full_type = gnat_desig_equiv;
                p->next = *head;
                *head = p;
              }
          }
      }
      break;

    case E_Access_Protected_Subprogram_Type:
    case E_Anonymous_Access_Protected_Subprogram_Type:
      if (type_annotate_only && No (gnat_equiv_type))
        gnu_type = ptr_void_type_node;
      else
        {
          /* The runtime representation is the equivalent type.  */
          gnu_type = gnat_to_gnu_type (gnat_equiv_type);
          maybe_present = true;
        }

      if (Is_Itype (Directly_Designated_Type (gnat_entity))
          && !present_gnu_tree (Directly_Designated_Type (gnat_entity))
          && No (Freeze_Node (Directly_Designated_Type (gnat_entity)))
          && !Is_Record_Type (Scope (Directly_Designated_Type (gnat_entity))))
        gnat_to_gnu_entity (Directly_Designated_Type (gnat_entity),
                            NULL_TREE, 0);

      break;

    case E_Access_Subtype:

      /* We treat this as identical to its base type; any constraint is
         meaningful only to the front end.

         The designated type must be elaborated as well, if it does
         not have its own freeze node.  Designated (sub)types created
         for constrained components of records with discriminants are
         not frozen by the front end and thus not elaborated by gigi,
         because their use may appear before the base type is frozen,
         and because it is not clear that they are needed anywhere in
         Gigi.  With the current model, there is no correct place where
         they could be elaborated.  */

      gnu_type = gnat_to_gnu_type (Etype (gnat_entity));
      if (Is_Itype (Directly_Designated_Type (gnat_entity))
          && !present_gnu_tree (Directly_Designated_Type (gnat_entity))
          && Is_Frozen (Directly_Designated_Type (gnat_entity))
          && No (Freeze_Node (Directly_Designated_Type (gnat_entity))))
        {
          /* If we are not defining this entity, and we have incomplete
             entities being processed above us, make a dummy type and
             elaborate it later.  */
          if (!definition && defer_incomplete_level != 0)
            {
              struct incomplete *p
                = (struct incomplete *) xmalloc (sizeof (struct incomplete));
              tree gnu_ptr_type
                = build_pointer_type
                  (make_dummy_type (Directly_Designated_Type (gnat_entity)));

              p->old_type = TREE_TYPE (gnu_ptr_type);
              p->full_type = Directly_Designated_Type (gnat_entity);
              p->next = defer_incomplete_list;
              defer_incomplete_list = p;
            }
          else if (!IN (Ekind (Base_Type
                              (Directly_Designated_Type (gnat_entity))),
                       Incomplete_Or_Private_Kind))
            gnat_to_gnu_entity (Directly_Designated_Type (gnat_entity),
                                NULL_TREE, 0);
        }

      maybe_present = true;
      break;

    /* Subprogram Entities

       The following access functions are defined for subprograms (functions
       or procedures):

                First_Formal    The first formal parameter.
                Is_Imported     Indicates that the subprogram has appeared in
                                an INTERFACE or IMPORT pragma.  For now we
                                assume that the external language is C.
                Is_Exported     Likewise but for an EXPORT pragma.
                Is_Inlined      True if the subprogram is to be inlined.

       In addition for function subprograms we have:

                Etype           Return type of the function.

       Each parameter is first checked by calling must_pass_by_ref on its
       type to determine if it is passed by reference.  For parameters which
       are copied in, if they are Ada In Out or Out parameters, their return
       value becomes part of a record which becomes the return type of the
       function (C function - note that this applies only to Ada procedures
       so there is no Ada return type).  Additional code to store back the
       parameters will be generated on the caller side.  This transformation
       is done here, not in the front-end.

       The intended result of the transformation can be seen from the
       equivalent source rewritings that follow:

                                                struct temp {int a,b};
       procedure P (A,B: In Out ...) is         temp P (int A,B)
       begin                                    {
         ..                                       ..
       end P;                                     return {A,B};
                                                }

                                                temp t;
       P(X,Y);                                  t = P(X,Y);
                                                X = t.a , Y = t.b;

       For subprogram types we need to perform mainly the same conversions to
       GCC form that are needed for procedures and function declarations.  The
       only difference is that at the end, we make a type declaration instead
       of a function declaration.  */

    case E_Subprogram_Type:
    case E_Function:
    case E_Procedure:
      {
        /* The first GCC parameter declaration (a PARM_DECL node).  The
           PARM_DECL nodes are chained through the TREE_CHAIN field, so this
           actually is the head of this parameter list.  */
        tree gnu_param_list = NULL_TREE;
        /* Likewise for the stub associated with an exported procedure.  */
        tree gnu_stub_param_list = NULL_TREE;
        /* The type returned by a function.  If the subprogram is a procedure
           this type should be void_type_node.  */
        tree gnu_return_type = void_type_node;
        /* List of fields in return type of procedure with copy-in copy-out
           parameters.  */
        tree gnu_field_list = NULL_TREE;
        /* Non-null for subprograms containing parameters passed by copy-in
           copy-out (Ada In Out or Out parameters not passed by reference),
           in which case it is the list of nodes used to specify the values of
           the in out/out parameters that are returned as a record upon
           procedure return.  The TREE_PURPOSE of an element of this list is
           a field of the record and the TREE_VALUE is the PARM_DECL
           corresponding to that field.  This list will be saved in the
           TYPE_CI_CO_LIST field of the FUNCTION_TYPE node we create.  */
        tree gnu_return_list = NULL_TREE;
        /* If an import pragma asks to map this subprogram to a GCC builtin,
           this is the builtin DECL node.  */
        tree gnu_builtin_decl = NULL_TREE;
        /* For the stub associated with an exported procedure.  */
        tree gnu_stub_type = NULL_TREE, gnu_stub_name = NULL_TREE;
        tree gnu_ext_name = create_concat_name (gnat_entity, NULL);
        Entity_Id gnat_param;
        bool inline_flag = Is_Inlined (gnat_entity);
        bool public_flag = Is_Public (gnat_entity) || imported_p;
        bool extern_flag
          = (Is_Public (gnat_entity) && !definition) || imported_p;

       /* The semantics of "pure" in Ada essentially matches that of "const"
          in the back-end.  In particular, both properties are orthogonal to
          the "nothrow" property if the EH circuitry is explicit in the
          internal representation of the back-end.  If we are to completely
          hide the EH circuitry from it, we need to declare that calls to pure
          Ada subprograms that can throw have side effects since they can
          trigger an "abnormal" transfer of control flow; thus they can be
          neither "const" nor "pure" in the back-end sense.  */
        bool const_flag
          = (Exception_Mechanism == Back_End_Exceptions
             && Is_Pure (gnat_entity));

        bool volatile_flag = No_Return (gnat_entity);
        bool returns_by_ref = false;
        bool returns_unconstrained = false;
        bool returns_by_target_ptr = false;
        bool has_copy_in_out = false;
        bool has_stub = false;
        int parmnum;

        if (kind == E_Subprogram_Type && !definition)
          /* A parameter may refer to this type, so defer completion
             of any incomplete types.  */
          defer_incomplete_level++, this_deferred = true;

        /* If the subprogram has an alias, it is probably inherited, so
           we can use the original one.  If the original "subprogram"
           is actually an enumeration literal, it may be the first use
           of its type, so we must elaborate that type now.  */
        if (Present (Alias (gnat_entity)))
          {
            if (Ekind (Alias (gnat_entity)) == E_Enumeration_Literal)
              gnat_to_gnu_entity (Etype (Alias (gnat_entity)), NULL_TREE, 0);

            gnu_decl = gnat_to_gnu_entity (Alias (gnat_entity),
                                           gnu_expr, 0);

            /* Elaborate any Itypes in the parameters of this entity.  */
            for (gnat_temp = First_Formal_With_Extras (gnat_entity);
                 Present (gnat_temp);
                 gnat_temp = Next_Formal_With_Extras (gnat_temp))
              if (Is_Itype (Etype (gnat_temp)))
                gnat_to_gnu_entity (Etype (gnat_temp), NULL_TREE, 0);

            break;
          }

        /* If this subprogram is expectedly bound to a GCC builtin, fetch the
           corresponding DECL node.

           We still want the parameter associations to take place because the
           proper generation of calls depends on it (a GNAT parameter without
           a corresponding GCC tree has a very specific meaning), so we don't
           just break here.  */
        if (Convention (gnat_entity) == Convention_Intrinsic)
          gnu_builtin_decl = builtin_decl_for (gnu_ext_name);

        /* ??? What if we don't find the builtin node above ? warn ? err ?
           In the current state we neither warn nor err, and calls will just
           be handled as for regular subprograms.  */

        if (kind == E_Function || kind == E_Subprogram_Type)
          gnu_return_type = gnat_to_gnu_type (Etype (gnat_entity));

        /* If this function returns by reference, make the actual
           return type of this function the pointer and mark the decl.  */
        if (Returns_By_Ref (gnat_entity))
          {
            returns_by_ref = true;
            gnu_return_type = build_pointer_type (gnu_return_type);
          }

        /* If the Mechanism is By_Reference, ensure the return type uses
           the machine's by-reference mechanism, which may not the same
           as above (e.g., it might be by passing a fake parameter).  */
        else if (kind == E_Function
                 && Mechanism (gnat_entity) == By_Reference)
          {
            TREE_ADDRESSABLE (gnu_return_type) = 1;

            /* We expect this bit to be reset by gigi shortly, so can avoid a
               type node copy here.  This actually also prevents troubles with
               the generation of debug information for the function, because
               we might have issued such info for this type already, and would
               be attaching a distinct type node to the function if we made a
               copy here.  */
          }

        /* If we are supposed to return an unconstrained array,
           actually return a fat pointer and make a note of that.  Return
           a pointer to an unconstrained record of variable size.  */
        else if (TREE_CODE (gnu_return_type) == UNCONSTRAINED_ARRAY_TYPE)
          {
            gnu_return_type = TREE_TYPE (gnu_return_type);
            returns_unconstrained = true;
          }

        /* If the type requires a transient scope, the result is allocated
           on the secondary stack, so the result type of the function is
           just a pointer.  */
        else if (Requires_Transient_Scope (Etype (gnat_entity)))
          {
            gnu_return_type = build_pointer_type (gnu_return_type);
            returns_unconstrained = true;
          }

        /* If the type is a padded type and the underlying type would not
           be passed by reference or this function has a foreign convention,
           return the underlying type.  */
        else if (TREE_CODE (gnu_return_type) == RECORD_TYPE
                 && TYPE_IS_PADDING_P (gnu_return_type)
                 && (!default_pass_by_ref (TREE_TYPE
                                           (TYPE_FIELDS (gnu_return_type)))
                     || Has_Foreign_Convention (gnat_entity)))
          gnu_return_type = TREE_TYPE (TYPE_FIELDS (gnu_return_type));

        /* If the return type has a non-constant size, we convert the function
           into a procedure and its caller will pass a pointer to an object as
           the first parameter when we call the function.  This can happen for
           an unconstrained type with a maximum size or a constrained type with
           a size not known at compile time.  */
        if (TYPE_SIZE_UNIT (gnu_return_type)
            && !TREE_CONSTANT (TYPE_SIZE_UNIT (gnu_return_type)))
          {
            returns_by_target_ptr = true;
            gnu_param_list
              = create_param_decl (get_identifier ("TARGET"),
                                   build_reference_type (gnu_return_type),
                                   true);
            gnu_return_type = void_type_node;
          }

        /* If the return type has a size that overflows, we cannot have
           a function that returns that type.  This usage doesn't make
           sense anyway, so give an error here.  */
        if (TYPE_SIZE_UNIT (gnu_return_type)
            && TREE_CONSTANT (TYPE_SIZE_UNIT (gnu_return_type))
            && TREE_OVERFLOW (TYPE_SIZE_UNIT (gnu_return_type)))
          {
            post_error ("cannot return type whose size overflows",
                        gnat_entity);
            gnu_return_type = copy_node (gnu_return_type);
            TYPE_SIZE (gnu_return_type) = bitsize_zero_node;
            TYPE_SIZE_UNIT (gnu_return_type) = size_zero_node;
            TYPE_MAIN_VARIANT (gnu_return_type) = gnu_return_type;
            TYPE_NEXT_VARIANT (gnu_return_type) = NULL_TREE;
          }

        /* Look at all our parameters and get the type of
           each.  While doing this, build a copy-out structure if
           we need one.  */

        /* Loop over the parameters and get their associated GCC tree.
           While doing this, build a copy-out structure if we need one.  */
        for (gnat_param = First_Formal_With_Extras (gnat_entity), parmnum = 0;
             Present (gnat_param);
             gnat_param = Next_Formal_With_Extras (gnat_param), parmnum++)
          {
            tree gnu_param_name = get_entity_name (gnat_param);
            tree gnu_param_type = gnat_to_gnu_type (Etype (gnat_param));
            tree gnu_param, gnu_field;
            bool copy_in_copy_out = false;
            Mechanism_Type mech = Mechanism (gnat_param);

            /* Builtins are expanded inline and there is no real call sequence
               involved.  So the type expected by the underlying expander is
               always the type of each argument "as is".  */
            if (gnu_builtin_decl)
              mech = By_Copy;
            /* Handle the first parameter of a valued procedure specially.  */
            else if (Is_Valued_Procedure (gnat_entity) && parmnum == 0)
              mech = By_Copy_Return;
            /* Otherwise, see if a Mechanism was supplied that forced this
               parameter to be passed one way or another.  */
            else if (mech == Default
                     || mech == By_Copy || mech == By_Reference)
              ;
            else if (By_Descriptor_Last <= mech && mech <= By_Descriptor)
              mech = By_Descriptor;

            else if (By_Short_Descriptor_Last <= mech &&
                     mech <= By_Short_Descriptor)
              mech = By_Short_Descriptor;

            else if (mech > 0)
              {
                if (TREE_CODE (gnu_param_type) == UNCONSTRAINED_ARRAY_TYPE
                    || TREE_CODE (TYPE_SIZE (gnu_param_type)) != INTEGER_CST
                    || 0 < compare_tree_int (TYPE_SIZE (gnu_param_type),
                                             mech))
                  mech = By_Reference;
                else
                  mech = By_Copy;
              }
            else
              {
                post_error ("unsupported mechanism for&", gnat_param);
                mech = Default;
              }

            gnu_param
              = gnat_to_gnu_param (gnat_param, mech, gnat_entity,
                                   Has_Foreign_Convention (gnat_entity),
                                   &copy_in_copy_out);

            /* We are returned either a PARM_DECL or a type if no parameter
               needs to be passed; in either case, adjust the type.  */
            if (DECL_P (gnu_param))
              gnu_param_type = TREE_TYPE (gnu_param);
            else
              {
                gnu_param_type = gnu_param;
                gnu_param = NULL_TREE;
              }

            if (gnu_param)
              {
                /* If it's an exported subprogram, we build a parameter list
                   in parallel, in case we need to emit a stub for it.  */
                if (Is_Exported (gnat_entity))
                  {
                    gnu_stub_param_list
                      = chainon (gnu_param, gnu_stub_param_list);
                    /* Change By_Descriptor parameter to By_Reference for
                       the internal version of an exported subprogram.  */
                    if (mech == By_Descriptor || mech == By_Short_Descriptor)
                      {
                        gnu_param
                          = gnat_to_gnu_param (gnat_param, By_Reference,
                                               gnat_entity, false,
                                               &copy_in_copy_out);
                        has_stub = true;
                      }
                    else
                      gnu_param = copy_node (gnu_param);
                  }

                gnu_param_list = chainon (gnu_param, gnu_param_list);
                Sloc_to_locus (Sloc (gnat_param),
                               &DECL_SOURCE_LOCATION (gnu_param));
                save_gnu_tree (gnat_param, gnu_param, false);

                /* If a parameter is a pointer, this function may modify
                   memory through it and thus shouldn't be considered
                   a const function.  Also, the memory may be modified
                   between two calls, so they can't be CSE'ed.  The latter
                   case also handles by-ref parameters.  */
                if (POINTER_TYPE_P (gnu_param_type)
                    || TYPE_FAT_POINTER_P (gnu_param_type))
                  const_flag = false;
              }

            if (copy_in_copy_out)
              {
                if (!has_copy_in_out)
                  {
                    gcc_assert (TREE_CODE (gnu_return_type) == VOID_TYPE);
                    gnu_return_type = make_node (RECORD_TYPE);
                    TYPE_NAME (gnu_return_type) = get_identifier ("RETURN");
                    has_copy_in_out = true;
                  }

                gnu_field = create_field_decl (gnu_param_name, gnu_param_type,
                                               gnu_return_type, 0, 0, 0, 0);
                Sloc_to_locus (Sloc (gnat_param),
                               &DECL_SOURCE_LOCATION (gnu_field));
                TREE_CHAIN (gnu_field) = gnu_field_list;
                gnu_field_list = gnu_field;
                gnu_return_list = tree_cons (gnu_field, gnu_param,
                                             gnu_return_list);
              }
          }

        /* Do not compute record for out parameters if subprogram is
           stubbed since structures are incomplete for the back-end.  */
        if (gnu_field_list && Convention (gnat_entity) != Convention_Stubbed)
          finish_record_type (gnu_return_type, nreverse (gnu_field_list),
                              0, false);

        /* If we have a CICO list but it has only one entry, we convert
           this function into a function that simply returns that one
           object.  */
        if (list_length (gnu_return_list) == 1)
          gnu_return_type = TREE_TYPE (TREE_PURPOSE (gnu_return_list));

        if (Has_Stdcall_Convention (gnat_entity))
          prepend_one_attribute_to
            (&attr_list, ATTR_MACHINE_ATTRIBUTE,
             get_identifier ("stdcall"), NULL_TREE,
             gnat_entity);

        /* If we are on a target where stack realignment is needed for 'main'
           to honor GCC's implicit expectations (stack alignment greater than
           what the base ABI guarantees), ensure we do the same for foreign
           convention subprograms as they might be used as callbacks from code
           breaking such expectations.  Note that this applies to task entry
           points in particular.  */
        if (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
            && Has_Foreign_Convention (gnat_entity))
          prepend_one_attribute_to
            (&attr_list, ATTR_MACHINE_ATTRIBUTE,
             get_identifier ("force_align_arg_pointer"), NULL_TREE,
             gnat_entity);

        /* The lists have been built in reverse.  */
        gnu_param_list = nreverse (gnu_param_list);
        if (has_stub)
          gnu_stub_param_list = nreverse (gnu_stub_param_list);
        gnu_return_list = nreverse (gnu_return_list);

        if (Ekind (gnat_entity) == E_Function)
          Set_Mechanism (gnat_entity,
                         (returns_by_ref || returns_unconstrained
                          ? By_Reference : By_Copy));
        gnu_type
          = create_subprog_type (gnu_return_type, gnu_param_list,
                                 gnu_return_list, returns_unconstrained,
                                 returns_by_ref, returns_by_target_ptr);

        if (has_stub)
          gnu_stub_type
            = create_subprog_type (gnu_return_type, gnu_stub_param_list,
                                   gnu_return_list, returns_unconstrained,
                                   returns_by_ref, returns_by_target_ptr);

        /* A subprogram (something that doesn't return anything) shouldn't
           be considered const since there would be no reason for such a
           subprogram.  Note that procedures with Out (or In Out) parameters
           have already been converted into a function with a return type.  */
        if (TREE_CODE (gnu_return_type) == VOID_TYPE)
          const_flag = false;

        gnu_type
          = build_qualified_type (gnu_type,
                                  TYPE_QUALS (gnu_type)
                                  | (TYPE_QUAL_CONST * const_flag)
                                  | (TYPE_QUAL_VOLATILE * volatile_flag));

        Sloc_to_locus (Sloc (gnat_entity), &input_location);

        if (has_stub)
          gnu_stub_type
            = build_qualified_type (gnu_stub_type,
                                    TYPE_QUALS (gnu_stub_type)
                                    | (TYPE_QUAL_CONST * const_flag)
                                    | (TYPE_QUAL_VOLATILE * volatile_flag));

        /* If we have a builtin decl for that function, check the signatures
           compatibilities.  If the signatures are compatible, use the builtin
           decl.  If they are not, we expect the checker predicate to have
           posted the appropriate errors, and just continue with what we have
           so far.  */
        if (gnu_builtin_decl)
          {
            tree gnu_builtin_type = TREE_TYPE (gnu_builtin_decl);

            if (compatible_signatures_p (gnu_type, gnu_builtin_type))
              {
                gnu_decl = gnu_builtin_decl;
                gnu_type = gnu_builtin_type;
                break;
              }
          }

        /* If there was no specified Interface_Name and the external and
           internal names of the subprogram are the same, only use the
           internal name to allow disambiguation of nested subprograms.  */
        if (No (Interface_Name (gnat_entity)) && gnu_ext_name == gnu_entity_id)
          gnu_ext_name = NULL_TREE;

        /* If we are defining the subprogram and it has an Address clause
           we must get the address expression from the saved GCC tree for the
           subprogram if it has a Freeze_Node.  Otherwise, we elaborate
           the address expression here since the front-end has guaranteed
           in that case that the elaboration has no effects.  If there is
           an Address clause and we are not defining the object, just
           make it a constant.  */
        if (Present (Address_Clause (gnat_entity)))
          {
            tree gnu_address = NULL_TREE;

            if (definition)
              gnu_address
                = (present_gnu_tree (gnat_entity)
                   ? get_gnu_tree (gnat_entity)
                   : gnat_to_gnu (Expression (Address_Clause (gnat_entity))));

            save_gnu_tree (gnat_entity, NULL_TREE, false);

            /* Convert the type of the object to a reference type that can
               alias everything as per 13.3(19).  */
            gnu_type
              = build_reference_type_for_mode (gnu_type, ptr_mode, true);
            if (gnu_address)
              gnu_address = convert (gnu_type, gnu_address);

            gnu_decl
              = create_var_decl (gnu_entity_id, gnu_ext_name, gnu_type,
                                 gnu_address, false, Is_Public (gnat_entity),
                                 extern_flag, false, NULL, gnat_entity);
            DECL_BY_REF_P (gnu_decl) = 1;
          }

        else if (kind == E_Subprogram_Type)
          gnu_decl = create_type_decl (gnu_entity_id, gnu_type, attr_list,
                                       !Comes_From_Source (gnat_entity),
                                       debug_info_p, gnat_entity);
        else
          {
            if (has_stub)
              {
                gnu_stub_name = gnu_ext_name;
                gnu_ext_name = create_concat_name (gnat_entity, "internal");
                public_flag = false;
              }

            gnu_decl = create_subprog_decl (gnu_entity_id, gnu_ext_name,
                                            gnu_type, gnu_param_list,
                                            inline_flag, public_flag,
                                            extern_flag, attr_list,
                                            gnat_entity);
            if (has_stub)
              {
                tree gnu_stub_decl
                  = create_subprog_decl (gnu_entity_id, gnu_stub_name,
                                         gnu_stub_type, gnu_stub_param_list,
                                         inline_flag, true,
                                         extern_flag, attr_list,
                                         gnat_entity);
                SET_DECL_FUNCTION_STUB (gnu_decl, gnu_stub_decl);
              }

            /* This is unrelated to the stub built right above.  */
            DECL_STUBBED_P (gnu_decl)
              = Convention (gnat_entity) == Convention_Stubbed;
          }
      }
      break;

    case E_Incomplete_Type:
    case E_Incomplete_Subtype:
    case E_Private_Type:
    case E_Private_Subtype:
    case E_Limited_Private_Type:
    case E_Limited_Private_Subtype:
    case E_Record_Type_With_Private:
    case E_Record_Subtype_With_Private:
      {
        /* Get the "full view" of this entity.  If this is an incomplete
           entity from a limited with, treat its non-limited view as the
           full view.  Otherwise, use either the full view or the underlying
           full view, whichever is present.  This is used in all the tests
           below.  */
        Entity_Id full_view
          = (IN (Ekind (gnat_entity), Incomplete_Kind)
             && From_With_Type (gnat_entity))
            ? Non_Limited_View (gnat_entity)
            : Present (Full_View (gnat_entity))
              ? Full_View (gnat_entity)
              : Underlying_Full_View (gnat_entity);

        /* If this is an incomplete type with no full view, it must be a Taft
           Amendment type, in which case we return a dummy type.  Otherwise,
           just get the type from its Etype.  */
        if (No (full_view))
          {
            if (kind == E_Incomplete_Type)
              {
                gnu_type = make_dummy_type (gnat_entity);
                gnu_decl = TYPE_STUB_DECL (gnu_type);
              }
            else
              {
                gnu_decl = gnat_to_gnu_entity (Etype (gnat_entity),
                                               NULL_TREE, 0);
                maybe_present = true;
              }
            break;
          }

        /* If we already made a type for the full view, reuse it.  */
        else if (present_gnu_tree (full_view))
          {
            gnu_decl = get_gnu_tree (full_view);
            break;
          }

        /* Otherwise, if we are not defining the type now, get the type
           from the full view.  But always get the type from the full view
           for define on use types, since otherwise we won't see them!  */
        else if (!definition
                 || (Is_Itype (full_view)
                   && No (Freeze_Node (gnat_entity)))
                 || (Is_Itype (gnat_entity)
                   && No (Freeze_Node (full_view))))
          {
            gnu_decl = gnat_to_gnu_entity (full_view, NULL_TREE, 0);
            maybe_present = true;
            break;
          }

        /* For incomplete types, make a dummy type entry which will be
           replaced later.  Save it as the full declaration's type so
           we can do any needed updates when we see it.  */
        gnu_type = make_dummy_type (gnat_entity);
        gnu_decl = TYPE_STUB_DECL (gnu_type);
        save_gnu_tree (full_view, gnu_decl, 0);
        break;
      }

      /* Simple class_wide types are always viewed as their root_type
         by Gigi unless an Equivalent_Type is specified.  */
    case E_Class_Wide_Type:
      gnu_decl = gnat_to_gnu_entity (gnat_equiv_type, NULL_TREE, 0);
      maybe_present = true;
      break;

    case E_Task_Type:
    case E_Task_Subtype:
    case E_Protected_Type:
    case E_Protected_Subtype:
      if (type_annotate_only && No (gnat_equiv_type))
        gnu_type = void_type_node;
      else
        gnu_type = gnat_to_gnu_type (gnat_equiv_type);

      maybe_present = true;
      break;

    case E_Label:
      gnu_decl = create_label_decl (gnu_entity_id);
      break;

    case E_Block:
    case E_Loop:
      /* Nothing at all to do here, so just return an ERROR_MARK and claim
         we've already saved it, so we don't try to.  */
      gnu_decl = error_mark_node;
      saved = true;
      break;

    default:
      gcc_unreachable ();
    }

  /* If we had a case where we evaluated another type and it might have
     defined this one, handle it here.  */
  if (maybe_present && present_gnu_tree (gnat_entity))
    {
      gnu_decl = get_gnu_tree (gnat_entity);
      saved = true;
    }

  /* If we are processing a type and there is either no decl for it or
     we just made one, do some common processing for the type, such as
     handling alignment and possible padding.  */

  if ((!gnu_decl || this_made_decl) && IN (kind, Type_Kind))
    {
      if (Is_Tagged_Type (gnat_entity)
          || Is_Class_Wide_Equivalent_Type (gnat_entity))
        TYPE_ALIGN_OK (gnu_type) = 1;

      if (AGGREGATE_TYPE_P (gnu_type) && Is_By_Reference_Type (gnat_entity))
        TYPE_BY_REFERENCE_P (gnu_type) = 1;

      /* ??? Don't set the size for a String_Literal since it is either
         confirming or we don't handle it properly (if the low bound is
         non-constant).  */
      if (!gnu_size && kind != E_String_Literal_Subtype)
        gnu_size = validate_size (Esize (gnat_entity), gnu_type, gnat_entity,
                                  TYPE_DECL, false,
                                  Has_Size_Clause (gnat_entity));

      /* If a size was specified, see if we can make a new type of that size
         by rearranging the type, for example from a fat to a thin pointer.  */
      if (gnu_size)
        {
          gnu_type
            = make_type_from_size (gnu_type, gnu_size,
                                   Has_Biased_Representation (gnat_entity));

          if (operand_equal_p (TYPE_SIZE (gnu_type), gnu_size, 0)
              && operand_equal_p (rm_size (gnu_type), gnu_size, 0))
            gnu_size = 0;
        }

      /* If the alignment hasn't already been processed and this is
         not an unconstrained array, see if an alignment is specified.
         If not, we pick a default alignment for atomic objects.  */
      if (align != 0 || TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE)
        ;
      else if (Known_Alignment (gnat_entity))
        {
          align = validate_alignment (Alignment (gnat_entity), gnat_entity,
                                      TYPE_ALIGN (gnu_type));

          /* Warn on suspiciously large alignments.  This should catch
             errors about the (alignment,byte)/(size,bit) discrepancy.  */
          if (align > BIGGEST_ALIGNMENT && Has_Alignment_Clause (gnat_entity))
            {
              tree size;

              /* If a size was specified, take it into account.  Otherwise
                 use the RM size for records as the type size has already
                 been adjusted to the alignment.  */
              if (gnu_size)
                size = gnu_size;
              else if ((TREE_CODE (gnu_type) == RECORD_TYPE
                        || TREE_CODE (gnu_type) == UNION_TYPE
                        || TREE_CODE (gnu_type) == QUAL_UNION_TYPE)
                       && !TYPE_IS_FAT_POINTER_P (gnu_type))
                size = rm_size (gnu_type);
              else
                size = TYPE_SIZE (gnu_type);

              /* Consider an alignment as suspicious if the alignment/size
                 ratio is greater or equal to the byte/bit ratio.  */
              if (host_integerp (size, 1)
                  && align >= TREE_INT_CST_LOW (size) * BITS_PER_UNIT)
                post_error_ne ("?suspiciously large alignment specified for&",
                               Expression (Alignment_Clause (gnat_entity)),
                               gnat_entity);
            }
        }
      else if (Is_Atomic (gnat_entity) && !gnu_size
               && host_integerp (TYPE_SIZE (gnu_type), 1)
               && integer_pow2p (TYPE_SIZE (gnu_type)))
        align = MIN (BIGGEST_ALIGNMENT,
                     tree_low_cst (TYPE_SIZE (gnu_type), 1));
      else if (Is_Atomic (gnat_entity) && gnu_size
               && host_integerp (gnu_size, 1)
               && integer_pow2p (gnu_size))
        align = MIN (BIGGEST_ALIGNMENT, tree_low_cst (gnu_size, 1));

      /* See if we need to pad the type.  If we did, and made a record,
         the name of the new type may be changed.  So get it back for
         us when we make the new TYPE_DECL below.  */
      if (gnu_size || align > 0)
        gnu_type = maybe_pad_type (gnu_type, gnu_size, align, gnat_entity,
                                   "PAD", true, definition, false);

      if (TREE_CODE (gnu_type) == RECORD_TYPE
          && TYPE_IS_PADDING_P (gnu_type))
        {
          gnu_entity_id = TYPE_NAME (gnu_type);
          if (TREE_CODE (gnu_entity_id) == TYPE_DECL)
            gnu_entity_id = DECL_NAME (gnu_entity_id);
        }

      set_rm_size (RM_Size (gnat_entity), gnu_type, gnat_entity);

      /* If we are at global level, GCC will have applied variable_size to
         the type, but that won't have done anything.  So, if it's not
         a constant or self-referential, call elaborate_expression_1 to
         make a variable for the size rather than calculating it each time.
         Handle both the RM size and the actual size.  */
      if (global_bindings_p ()
          && TYPE_SIZE (gnu_type)
          && !TREE_CONSTANT (TYPE_SIZE (gnu_type))
          && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type)))
        {
          if (TREE_CODE (gnu_type) == RECORD_TYPE
              && operand_equal_p (TYPE_ADA_SIZE (gnu_type),
                                  TYPE_SIZE (gnu_type), 0))
            {
              TYPE_SIZE (gnu_type)
                = elaborate_expression_1 (gnat_entity, gnat_entity,
                                          TYPE_SIZE (gnu_type),
                                          get_identifier ("SIZE"),
                                          definition, 0);
              SET_TYPE_ADA_SIZE (gnu_type, TYPE_SIZE (gnu_type));
            }
          else
            {
              TYPE_SIZE (gnu_type)
                = elaborate_expression_1 (gnat_entity, gnat_entity,
                                          TYPE_SIZE (gnu_type),
                                          get_identifier ("SIZE"),
                                          definition, 0);

              /* ??? For now, store the size as a multiple of the alignment
                 in bytes so that we can see the alignment from the tree.  */
              TYPE_SIZE_UNIT (gnu_type)
                = build_binary_op
                  (MULT_EXPR, sizetype,
                   elaborate_expression_1
                   (gnat_entity, gnat_entity,
                    build_binary_op (EXACT_DIV_EXPR, sizetype,
                                     TYPE_SIZE_UNIT (gnu_type),
                                     size_int (TYPE_ALIGN (gnu_type)
                                               / BITS_PER_UNIT)),
                    get_identifier ("SIZE_A_UNIT"),
                    definition, 0),
                   size_int (TYPE_ALIGN (gnu_type) / BITS_PER_UNIT));

              if (TREE_CODE (gnu_type) == RECORD_TYPE)
                SET_TYPE_ADA_SIZE
                  (gnu_type,
                   elaborate_expression_1 (gnat_entity,
                                           gnat_entity,
                                           TYPE_ADA_SIZE (gnu_type),
                                           get_identifier ("RM_SIZE"),
                                           definition, 0));
                 }
        }

      /* If this is a record type or subtype, call elaborate_expression_1 on
         any field position.  Do this for both global and local types.
         Skip any fields that we haven't made trees for to avoid problems with
         class wide types.  */
      if (IN (kind, Record_Kind))
        for (gnat_temp = First_Entity (gnat_entity); Present (gnat_temp);
             gnat_temp = Next_Entity (gnat_temp))
          if (Ekind (gnat_temp) == E_Component && present_gnu_tree (gnat_temp))
            {
              tree gnu_field = get_gnu_tree (gnat_temp);

              /* ??? Unfortunately, GCC needs to be able to prove the
                 alignment of this offset and if it's a variable, it can't.
                 In GCC 3.4, we'll use DECL_OFFSET_ALIGN in some way, but
                 right now, we have to put in an explicit multiply and
                 divide by that value.  */
              if (!CONTAINS_PLACEHOLDER_P (DECL_FIELD_OFFSET (gnu_field)))
                {
                DECL_FIELD_OFFSET (gnu_field)
                  = build_binary_op
                    (MULT_EXPR, sizetype,
                     elaborate_expression_1
                     (gnat_temp, gnat_temp,
                      build_binary_op (EXACT_DIV_EXPR, sizetype,
                                       DECL_FIELD_OFFSET (gnu_field),
                                       size_int (DECL_OFFSET_ALIGN (gnu_field)
                                                 / BITS_PER_UNIT)),
                      get_identifier ("OFFSET"),
                      definition, 0),
                     size_int (DECL_OFFSET_ALIGN (gnu_field) / BITS_PER_UNIT));

                /* ??? The context of gnu_field is not necessarily gnu_type so
                   the MULT_EXPR node built above may not be marked by the call
                   to create_type_decl below.  */
                if (global_bindings_p ())
                  mark_visited (&DECL_FIELD_OFFSET (gnu_field));
                }
            }

      gnu_type = build_qualified_type (gnu_type,
                                       (TYPE_QUALS (gnu_type)
                                        | (TYPE_QUAL_VOLATILE
                                           * Treat_As_Volatile (gnat_entity))));

      if (Is_Atomic (gnat_entity))
        check_ok_for_atomic (gnu_type, gnat_entity, false);

      if (Present (Alignment_Clause (gnat_entity)))
        TYPE_USER_ALIGN (gnu_type) = 1;

      if (Universal_Aliasing (gnat_entity))
        TYPE_UNIVERSAL_ALIASING_P (TYPE_MAIN_VARIANT (gnu_type)) = 1;

      if (!gnu_decl)
        gnu_decl = create_type_decl (gnu_entity_id, gnu_type, attr_list,
                                     !Comes_From_Source (gnat_entity),
                                     debug_info_p, gnat_entity);
      else
        TREE_TYPE (gnu_decl) = gnu_type;
    }

  if (IN (kind, Type_Kind) && !TYPE_IS_DUMMY_P (TREE_TYPE (gnu_decl)))
    {
      gnu_type = TREE_TYPE (gnu_decl);

      /* If this is a derived type, relate its alias set to that of its parent
         to avoid troubles when a call to an inherited primitive is inlined in
         a context where a derived object is accessed.  The inlined code works
         on the parent view so the resulting code may access the same object
         using both the parent and the derived alias sets, which thus have to
         conflict.  As the same issue arises with component references, the
         parent alias set also has to conflict with composite types enclosing
         derived components.  For instance, if we have:

            type D is new T;
            type R is record
               Component : D;
            end record;

         we want T to conflict with both D and R, in addition to R being a
         superset of D by record/component construction.

         One way to achieve this is to perform an alias set copy from the
         parent to the derived type.  This is not quite appropriate, though,
         as we don't want separate derived types to conflict with each other:

            type I1 is new Integer;
            type I2 is new Integer;

         We want I1 and I2 to both conflict with Integer but we do not want
         I1 to conflict with I2, and an alias set copy on derivation would
         have that effect.

         The option chosen is to make the alias set of the derived type a
         superset of that of its parent type.  It trivially fulfills the
         simple requirement for the Integer derivation example above, and
         the component case as well by superset transitivity:

                   superset      superset
                R ----------> D ----------> T

         The language rules ensure the parent type is already frozen here.  */
      if (Is_Derived_Type (gnat_entity))
        {
          tree gnu_parent_type = gnat_to_gnu_type (Etype (gnat_entity));
          relate_alias_sets (gnu_type, gnu_parent_type, ALIAS_SET_SUPERSET);
        }

      /* Back-annotate the Alignment of the type if not already in the
         tree.  Likewise for sizes.  */
      if (Unknown_Alignment (gnat_entity))
        Set_Alignment (gnat_entity,
                       UI_From_Int (TYPE_ALIGN (gnu_type) / BITS_PER_UNIT));

      if (Unknown_Esize (gnat_entity) && TYPE_SIZE (gnu_type))
        {
          /* If the size is self-referential, we annotate the maximum
             value of that size.  */
          tree gnu_size = TYPE_SIZE (gnu_type);

          if (CONTAINS_PLACEHOLDER_P (gnu_size))
            gnu_size = max_size (gnu_size, true);

          Set_Esize (gnat_entity, annotate_value (gnu_size));

          if (type_annotate_only && Is_Tagged_Type (gnat_entity))
            {
              /* In this mode the tag and the parent components are not
                 generated by the front-end, so the sizes must be adjusted
                 explicitly now.  */
              int size_offset, new_size;

              if (Is_Derived_Type (gnat_entity))
                {
                  size_offset
                    = UI_To_Int (Esize (Etype (Base_Type (gnat_entity))));
                  Set_Alignment (gnat_entity,
                                 Alignment (Etype (Base_Type (gnat_entity))));
                }
              else
                size_offset = POINTER_SIZE;

              new_size = UI_To_Int (Esize (gnat_entity)) + size_offset;
              Set_Esize (gnat_entity,
                         UI_From_Int (((new_size + (POINTER_SIZE - 1))
                                       / POINTER_SIZE) * POINTER_SIZE));
              Set_RM_Size (gnat_entity, Esize (gnat_entity));
            }
        }

      if (Unknown_RM_Size (gnat_entity) && rm_size (gnu_type))
        Set_RM_Size (gnat_entity, annotate_value (rm_size (gnu_type)));
    }

  if (!Comes_From_Source (gnat_entity) && DECL_P (gnu_decl))
    DECL_ARTIFICIAL (gnu_decl) = 1;

  if (!debug_info_p && DECL_P (gnu_decl)
      && TREE_CODE (gnu_decl) != FUNCTION_DECL
      && No (Renamed_Object (gnat_entity)))
    DECL_IGNORED_P (gnu_decl) = 1;

  /* If we haven't already, associate the ..._DECL node that we just made with
     the input GNAT entity node.  */
  if (!saved)
    save_gnu_tree (gnat_entity, gnu_decl, false);

  /* If this is an enumeral or floating-point type, we were not able to set
     the bounds since they refer to the type.  These bounds are always static.

     For enumeration types, also write debugging information and declare the
     enumeration literal  table, if needed.  */

  if ((kind == E_Enumeration_Type && Present (First_Literal (gnat_entity)))
      || (kind == E_Floating_Point_Type && !Vax_Float (gnat_entity)))
    {
      tree gnu_scalar_type = gnu_type;

      /* If this is a padded type, we need to use the underlying type.  */
      if (TREE_CODE (gnu_scalar_type) == RECORD_TYPE
          && TYPE_IS_PADDING_P (gnu_scalar_type))
        gnu_scalar_type = TREE_TYPE (TYPE_FIELDS (gnu_scalar_type));

      /* If this is a floating point type and we haven't set a floating
         point type yet, use this in the evaluation of the bounds.  */
      if (!longest_float_type_node && kind == E_Floating_Point_Type)
        longest_float_type_node = gnu_type;

      TYPE_MIN_VALUE (gnu_scalar_type)
        = gnat_to_gnu (Type_Low_Bound (gnat_entity));
      TYPE_MAX_VALUE (gnu_scalar_type)
        = gnat_to_gnu (Type_High_Bound (gnat_entity));

      if (TREE_CODE (gnu_scalar_type) == ENUMERAL_TYPE)
        {
          /* Since this has both a typedef and a tag, avoid outputting
             the name twice.  */
          DECL_ARTIFICIAL (gnu_decl) = 1;
          rest_of_type_decl_compilation (gnu_decl);
        }
    }

  /* If we deferred processing of incomplete types, re-enable it.  If there
     were no other disables and we have some to process, do so.  */
  if (this_deferred && --defer_incomplete_level == 0)
    {
      if (defer_incomplete_list)
        {
          struct incomplete *incp, *next;

          /* We are back to level 0 for the deferring of incomplete types.
             But processing these incomplete types below may itself require
             deferring, so preserve what we have and restart from scratch.  */
          incp = defer_incomplete_list;
          defer_incomplete_list = NULL;

          /* For finalization, however, all types must be complete so we
             cannot do the same because deferred incomplete types may end up
             referencing each other.  Process them all recursively first.  */
          defer_finalize_level++;

          for (; incp; incp = next)
            {
              next = incp->next;

              if (incp->old_type)
                update_pointer_to (TYPE_MAIN_VARIANT (incp->old_type),
                                   gnat_to_gnu_type (incp->full_type));
              free (incp);
            }

          defer_finalize_level--;
        }

      /* All the deferred incomplete types have been processed so we can
         now proceed with the finalization of the deferred types.  */
      if (defer_finalize_level == 0 && defer_finalize_list)
        {
          unsigned int i;
          tree t;

          for (i = 0; VEC_iterate (tree, defer_finalize_list, i, t); i++)
            rest_of_type_decl_compilation_no_defer (t);

          VEC_free (tree, heap, defer_finalize_list);
        }
    }

  /* If we are not defining this type, see if it's in the incomplete list.
     If so, handle that list entry now.  */
  else if (!definition)
    {
      struct incomplete *incp;

      for (incp = defer_incomplete_list; incp; incp = incp->next)
        if (incp->old_type && incp->full_type == gnat_entity)
          {
            update_pointer_to (TYPE_MAIN_VARIANT (incp->old_type),
                               TREE_TYPE (gnu_decl));
            incp->old_type = NULL_TREE;
          }
    }

  if (this_global)
    force_global--;

  if (Is_Packed_Array_Type (gnat_entity)
      && Is_Itype (Associated_Node_For_Itype (gnat_entity))
      && No (Freeze_Node (Associated_Node_For_Itype (gnat_entity)))
      && !present_gnu_tree (Associated_Node_For_Itype (gnat_entity)))
    gnat_to_gnu_entity (Associated_Node_For_Itype (gnat_entity), NULL_TREE, 0);

  return gnu_decl;
}

/* Similar, but if the returned value is a COMPONENT_REF, return the
   FIELD_DECL.  */

tree
gnat_to_gnu_field_decl (Entity_Id gnat_entity)
{
  tree gnu_field = gnat_to_gnu_entity (gnat_entity, NULL_TREE, 0);

  if (TREE_CODE (gnu_field) == COMPONENT_REF)
    gnu_field = TREE_OPERAND (gnu_field, 1);

  return gnu_field;
}

/* Similar, but GNAT_ENTITY is assumed to refer to a GNAT type.  Return
   the GCC type corresponding to that entity.  */

tree
gnat_to_gnu_type (Entity_Id gnat_entity)
{
  tree gnu_decl;

  /* The back end never attempts to annotate generic types.  */
  if (Is_Generic_Type (gnat_entity) && type_annotate_only)
     return void_type_node;

  gnu_decl = gnat_to_gnu_entity (gnat_entity, NULL_TREE, 0);
  gcc_assert (TREE_CODE (gnu_decl) == TYPE_DECL);

  return TREE_TYPE (gnu_decl);
}

/* Similar, but GNAT_ENTITY is assumed to refer to a GNAT type.  Return
   the unpadded version of the GCC type corresponding to that entity.  */

tree
get_unpadded_type (Entity_Id gnat_entity)
{
  tree type = gnat_to_gnu_type (gnat_entity);

  if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
    type = TREE_TYPE (TYPE_FIELDS (type));

  return type;
}
\f
/* Wrap up compilation of DECL, a TYPE_DECL, possibly deferring it.
   Every TYPE_DECL generated for a type definition must be passed
   to this function once everything else has been done for it.  */

void
rest_of_type_decl_compilation (tree decl)
{
  /* We need to defer finalizing the type if incomplete types
     are being deferred or if they are being processed.  */
  if (defer_incomplete_level || defer_finalize_level)
    VEC_safe_push (tree, heap, defer_finalize_list, decl);
  else
    rest_of_type_decl_compilation_no_defer (decl);
}

/* Same as above but without deferring the compilation.  This
   function should not be invoked directly on a TYPE_DECL.  */

static void
rest_of_type_decl_compilation_no_defer (tree decl)
{
  const int toplev = global_bindings_p ();
  tree t = TREE_TYPE (decl);

  rest_of_decl_compilation (decl, toplev, 0);

  /* Now process all the variants.  This is needed for STABS.  */
  for (t = TYPE_MAIN_VARIANT (t); t; t = TYPE_NEXT_VARIANT (t))
    {
      if (t == TREE_TYPE (decl))
        continue;

      if (!TYPE_STUB_DECL (t))
        TYPE_STUB_DECL (t) = create_type_stub_decl (DECL_NAME (decl), t);

      rest_of_type_compilation (t, toplev);
    }
}

/* Finalize any From_With_Type incomplete types.  We do this after processing
   our compilation unit and after processing its spec, if this is a body.  */

void
finalize_from_with_types (void)
{
  struct incomplete *incp = defer_limited_with;
  struct incomplete *next;

  defer_limited_with = 0;
  for (; incp; incp = next)
    {
      next = incp->next;

      if (incp->old_type != 0)
        update_pointer_to (TYPE_MAIN_VARIANT (incp->old_type),
                           gnat_to_gnu_type (incp->full_type));
      free (incp);
    }
}

/* Return the equivalent type to be used for GNAT_ENTITY, if it's a
   kind of type (such E_Task_Type) that has a different type which Gigi
   uses for its representation.  If the type does not have a special type
   for its representation, return GNAT_ENTITY.  If a type is supposed to
   exist, but does not, abort unless annotating types, in which case
   return Empty.  If GNAT_ENTITY is Empty, return Empty.  */

Entity_Id
Gigi_Equivalent_Type (Entity_Id gnat_entity)
{
  Entity_Id gnat_equiv = gnat_entity;

  if (No (gnat_entity))
    return gnat_entity;

  switch (Ekind (gnat_entity))
    {
    case E_Class_Wide_Subtype:
      if (Present (Equivalent_Type (gnat_entity)))
        gnat_equiv = Equivalent_Type (gnat_entity);
      break;

    case E_Access_Protected_Subprogram_Type:
    case E_Anonymous_Access_Protected_Subprogram_Type:
      gnat_equiv = Equivalent_Type (gnat_entity);
      break;

    case E_Class_Wide_Type:
      gnat_equiv = ((Present (Equivalent_Type (gnat_entity)))
                    ? Equivalent_Type (gnat_entity)
                    : Root_Type (gnat_entity));
      break;

    case E_Task_Type:
    case E_Task_Subtype:
    case E_Protected_Type:
    case E_Protected_Subtype:
      gnat_equiv = Corresponding_Record_Type (gnat_entity);
      break;

    default:
      break;
    }

  gcc_assert (Present (gnat_equiv) || type_annotate_only);
  return gnat_equiv;
}

/* Return a GCC tree for a parameter corresponding to GNAT_PARAM and
   using MECH as its passing mechanism, to be placed in the parameter
   list built for GNAT_SUBPROG.  Assume a foreign convention for the
   latter if FOREIGN is true.  Also set CICO to true if the parameter
   must use the copy-in copy-out implementation mechanism.

   The returned tree is a PARM_DECL, except for those cases where no
   parameter needs to be actually passed to the subprogram; the type
   of this "shadow" parameter is then returned instead.  */

static tree
gnat_to_gnu_param (Entity_Id gnat_param, Mechanism_Type mech,
                   Entity_Id gnat_subprog, bool foreign, bool *cico)
{
  tree gnu_param_name = get_entity_name (gnat_param);
  tree gnu_param_type = gnat_to_gnu_type (Etype (gnat_param));
  tree gnu_param_type_alt = NULL_TREE;
  bool in_param = (Ekind (gnat_param) == E_In_Parameter);
  /* The parameter can be indirectly modified if its address is taken.  */
  bool ro_param = in_param && !Address_Taken (gnat_param);
  bool by_return = false, by_component_ptr = false, by_ref = false;
  tree gnu_param;

  /* Copy-return is used only for the first parameter of a valued procedure.
     It's a copy mechanism for which a parameter is never allocated.  */
  if (mech == By_Copy_Return)
    {
      gcc_assert (Ekind (gnat_param) == E_Out_Parameter);
      mech = By_Copy;
      by_return = true;
    }

  /* If this is either a foreign function or if the underlying type won't
     be passed by reference, strip off possible padding type.  */
  if (TREE_CODE (gnu_param_type) == RECORD_TYPE
      && TYPE_IS_PADDING_P (gnu_param_type))
    {
      tree unpadded_type = TREE_TYPE (TYPE_FIELDS (gnu_param_type));

      if (mech == By_Reference
          || foreign
          || (!must_pass_by_ref (unpadded_type)
              && (mech == By_Copy || !default_pass_by_ref (unpadded_type))))
        gnu_param_type = unpadded_type;
    }

  /* If this is a read-only parameter, make a variant of the type that is
     read-only.  ??? However, if this is an unconstrained array, that type
     can be very complex, so skip it for now.  Likewise for any other
     self-referential type.  */
  if (ro_param
      && TREE_CODE (gnu_param_type) != UNCONSTRAINED_ARRAY_TYPE
      && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_param_type)))
    gnu_param_type = build_qualified_type (gnu_param_type,
                                           (TYPE_QUALS (gnu_param_type)
                                            | TYPE_QUAL_CONST));

  /* For foreign conventions, pass arrays as pointers to the element type.
     First check for unconstrained array and get the underlying array.  */
  if (foreign && TREE_CODE (gnu_param_type) == UNCONSTRAINED_ARRAY_TYPE)
    gnu_param_type
      = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_param_type))));

  /* VMS descriptors are themselves passed by reference.  */
  if (mech == By_Short_Descriptor ||
      (mech == By_Descriptor && TARGET_ABI_OPEN_VMS && !TARGET_MALLOC64))
    gnu_param_type
      = build_pointer_type (build_vms_descriptor32 (gnu_param_type,
                                                    Mechanism (gnat_param),
                                                    gnat_subprog));
  else if (mech == By_Descriptor)
    {
      /* Build both a 32-bit and 64-bit descriptor, one of which will be
         chosen in fill_vms_descriptor.  */
      gnu_param_type_alt
        = build_pointer_type (build_vms_descriptor32 (gnu_param_type,
                                                      Mechanism (gnat_param),
                                                      gnat_subprog));
      gnu_param_type
        = build_pointer_type (build_vms_descriptor (gnu_param_type,
                                                    Mechanism (gnat_param),
                                                    gnat_subprog));
    }

  /* Arrays are passed as pointers to element type for foreign conventions.  */
  else if (foreign
           && mech != By_Copy
           && TREE_CODE (gnu_param_type) == ARRAY_TYPE)
    {
      /* Strip off any multi-dimensional entries, then strip
         off the last array to get the component type.  */
      while (TREE_CODE (TREE_TYPE (gnu_param_type)) == ARRAY_TYPE
             && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_param_type)))
        gnu_param_type = TREE_TYPE (gnu_param_type);

      by_component_ptr = true;
      gnu_param_type = TREE_TYPE (gnu_param_type);

      if (ro_param)
        gnu_param_type = build_qualified_type (gnu_param_type,
                                               (TYPE_QUALS (gnu_param_type)
                                                | TYPE_QUAL_CONST));

      gnu_param_type = build_pointer_type (gnu_param_type);
    }

  /* Fat pointers are passed as thin pointers for foreign conventions.  */
  else if (foreign && TYPE_FAT_POINTER_P (gnu_param_type))
    gnu_param_type
      = make_type_from_size (gnu_param_type, size_int (POINTER_SIZE), 0);

  /* If we must pass or were requested to pass by reference, do so.
     If we were requested to pass by copy, do so.
     Otherwise, for foreign conventions, pass In Out or Out parameters
     or aggregates by reference.  For COBOL and Fortran, pass all
     integer and FP types that way too.  For Convention Ada, use
     the standard Ada default.  */
  else if (must_pass_by_ref (gnu_param_type)
           || mech == By_Reference
           || (mech != By_Copy
               && ((foreign
                    && (!in_param || AGGREGATE_TYPE_P (gnu_param_type)))
                   || (foreign
                       && (Convention (gnat_subprog) == Convention_Fortran
                           || Convention (gnat_subprog) == Convention_COBOL)
                       && (INTEGRAL_TYPE_P (gnu_param_type)
                           || FLOAT_TYPE_P (gnu_param_type)))
                   || (!foreign
                       && default_pass_by_ref (gnu_param_type)))))
    {
      gnu_param_type = build_reference_type (gnu_param_type);
      by_ref = true;
    }

  /* Pass In Out or Out parameters using copy-in copy-out mechanism.  */
  else if (!in_param)
    *cico = true;

  if (mech == By_Copy && (by_ref || by_component_ptr))
    post_error ("?cannot pass & by copy", gnat_param);

  /* If this is an Out parameter that isn't passed by reference and isn't
     a pointer or aggregate, we don't make a PARM_DECL for it.  Instead,
     it will be a VAR_DECL created when we process the procedure, so just
     return its type.  For the special parameter of a valued procedure,
     never pass it in.

     An exception is made to cover the RM-6.4.1 rule requiring "by copy"
     Out parameters with discriminants or implicit initial values to be
     handled like In Out parameters.  These type are normally built as
     aggregates, hence passed by reference, except for some packed arrays
     which end up encoded in special integer types.

     The exception we need to make is then for packed arrays of records
     with discriminants or implicit initial values.  We have no light/easy
     way to check for the latter case, so we merely check for packed arrays
     of records.  This may lead to useless copy-in operations, but in very
     rare cases only, as these would be exceptions in a set of already
     exceptional situations.  */
  if (Ekind (gnat_param) == E_Out_Parameter
      && !by_ref
      && (by_return
          || (mech != By_Descriptor
              && mech != By_Short_Descriptor
              && !POINTER_TYPE_P (gnu_param_type)
              && !AGGREGATE_TYPE_P (gnu_param_type)))
      && !(Is_Array_Type (Etype (gnat_param))
           && Is_Packed (Etype (gnat_param))
           && Is_Composite_Type (Component_Type (Etype (gnat_param)))))
    return gnu_param_type;

  gnu_param = create_param_decl (gnu_param_name, gnu_param_type,
                                 ro_param || by_ref || by_component_ptr);
  DECL_BY_REF_P (gnu_param) = by_ref;
  DECL_BY_COMPONENT_PTR_P (gnu_param) = by_component_ptr;
  DECL_BY_DESCRIPTOR_P (gnu_param) = (mech == By_Descriptor ||
                                      mech == By_Short_Descriptor);
  DECL_POINTS_TO_READONLY_P (gnu_param)
    = (ro_param && (by_ref || by_component_ptr));

  /* Save the alternate descriptor type, if any.  */
  if (gnu_param_type_alt)
    SET_DECL_PARM_ALT_TYPE (gnu_param, gnu_param_type_alt);

  /* If no Mechanism was specified, indicate what we're using, then
     back-annotate it.  */
  if (mech == Default)
    mech = (by_ref || by_component_ptr) ? By_Reference : By_Copy;

  Set_Mechanism (gnat_param, mech);
  return gnu_param;
}

/* Return true if DISCR1 and DISCR2 represent the same discriminant.  */

static bool
same_discriminant_p (Entity_Id discr1, Entity_Id discr2)
{
  while (Present (Corresponding_Discriminant (discr1)))
    discr1 = Corresponding_Discriminant (discr1);

  while (Present (Corresponding_Discriminant (discr2)))
    discr2 = Corresponding_Discriminant (discr2);

  return
    Original_Record_Component (discr1) == Original_Record_Component (discr2);
}

/* Return true if the array type specified by GNAT_TYPE and GNU_TYPE has
   a non-aliased component in the back-end sense.  */

static bool
array_type_has_nonaliased_component (Entity_Id gnat_type, tree gnu_type)
{
  /* If the type below this is a multi-array type, then
     this does not have aliased components.  */
  if (TREE_CODE (TREE_TYPE (gnu_type)) == ARRAY_TYPE
      && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_type)))
    return true;

  if (Has_Aliased_Components (gnat_type))
    return false;

  return type_for_nonaliased_component_p (TREE_TYPE (gnu_type));
}

/* Return true if GNAT_ADDRESS is a value known at compile-time.  */

static bool
compile_time_known_address_p (Node_Id gnat_address)
{
  /* Catch System'To_Address.  */
  if (Nkind (gnat_address) == N_Unchecked_Type_Conversion)
    gnat_address = Expression (gnat_address);

  return Compile_Time_Known_Value (gnat_address);
}
\f
/* Given GNAT_ENTITY, elaborate all expressions that are required to
   be elaborated at the point of its definition, but do nothing else.  */

void
elaborate_entity (Entity_Id gnat_entity)
{
  switch (Ekind (gnat_entity))
    {
    case E_Signed_Integer_Subtype:
    case E_Modular_Integer_Subtype:
    case E_Enumeration_Subtype:
    case E_Ordinary_Fixed_Point_Subtype:
    case E_Decimal_Fixed_Point_Subtype:
    case E_Floating_Point_Subtype:
      {
        Node_Id gnat_lb = Type_Low_Bound (gnat_entity);
        Node_Id gnat_hb = Type_High_Bound (gnat_entity);

        /* ??? Tests for avoiding static constraint error expression
           is needed until the front stops generating bogus conversions
           on bounds of real types.  */

        if (!Raises_Constraint_Error (gnat_lb))
          elaborate_expression (gnat_lb, gnat_entity, get_identifier ("L"),
                                1, 0, Needs_Debug_Info (gnat_entity));
        if (!Raises_Constraint_Error (gnat_hb))
          elaborate_expression (gnat_hb, gnat_entity, get_identifier ("U"),
                                1, 0, Needs_Debug_Info (gnat_entity));
      break;
      }

    case E_Record_Type:
      {
        Node_Id full_definition = Declaration_Node (gnat_entity);
        Node_Id record_definition = Type_Definition (full_definition);

        /* If this is a record extension, go a level further to find the
           record definition.  */
        if (Nkind (record_definition) == N_Derived_Type_Definition)
          record_definition = Record_Extension_Part (record_definition);
      }
      break;

    case E_Record_Subtype:
    case E_Private_Subtype:
    case E_Limited_Private_Subtype:
    case E_Record_Subtype_With_Private:
      if (Is_Constrained (gnat_entity)
          && Has_Discriminants (Base_Type (gnat_entity))
          && Present (Discriminant_Constraint (gnat_entity)))
        {
          Node_Id gnat_discriminant_expr;
          Entity_Id gnat_field;

          for (gnat_field = First_Discriminant (Base_Type (gnat_entity)),
               gnat_discriminant_expr
               = First_Elmt (Discriminant_Constraint (gnat_entity));
               Present (gnat_field);
               gnat_field = Next_Discriminant (gnat_field),
               gnat_discriminant_expr = Next_Elmt (gnat_discriminant_expr))
            /* ??? For now, ignore access discriminants.  */
            if (!Is_Access_Type (Etype (Node (gnat_discriminant_expr))))
              elaborate_expression (Node (gnat_discriminant_expr),
                                    gnat_entity,
                                    get_entity_name (gnat_field), 1, 0, 0);
        }
      break;

    }
}
\f
/* Mark GNAT_ENTITY as going out of scope at this point.  Recursively mark
   any entities on its entity chain similarly.  */

void
mark_out_of_scope (Entity_Id gnat_entity)
{
  Entity_Id gnat_sub_entity;
  unsigned int kind = Ekind (gnat_entity);

  /* If this has an entity list, process all in the list.  */
  if (IN (kind, Class_Wide_Kind) || IN (kind, Concurrent_Kind)
      || IN (kind, Private_Kind)
      || kind == E_Block || kind == E_Entry || kind == E_Entry_Family
      || kind == E_Function || kind == E_Generic_Function
      || kind == E_Generic_Package || kind == E_Generic_Procedure
      || kind == E_Loop || kind == E_Operator || kind == E_Package
      || kind == E_Package_Body || kind == E_Procedure
      || kind == E_Record_Type || kind == E_Record_Subtype
      || kind == E_Subprogram_Body || kind == E_Subprogram_Type)
    for (gnat_sub_entity = First_Entity (gnat_entity);
         Present (gnat_sub_entity);
         gnat_sub_entity = Next_Entity (gnat_sub_entity))
      if (Scope (gnat_sub_entity) == gnat_entity
          && gnat_sub_entity != gnat_entity)
        mark_out_of_scope (gnat_sub_entity);

  /* Now clear this if it has been defined, but only do so if it isn't
     a subprogram or parameter.  We could refine this, but it isn't
     worth it.  If this is statically allocated, it is supposed to
     hang around out of cope.  */
  if (present_gnu_tree (gnat_entity) && !Is_Statically_Allocated (gnat_entity)
      && kind != E_Procedure && kind != E_Function && !IN (kind, Formal_Kind))
    {
      save_gnu_tree (gnat_entity, NULL_TREE, true);
      save_gnu_tree (gnat_entity, error_mark_node, true);
    }
}
\f
/* Relate the alias sets of GNU_NEW_TYPE and GNU_OLD_TYPE according to OP.
   If this is a multi-dimensional array type, do this recursively.

   OP may be
   - ALIAS_SET_COPY:     the new set is made a copy of the old one.
   - ALIAS_SET_SUPERSET: the new set is made a superset of the old one.
   - ALIAS_SET_SUBSET:   the new set is made a subset of the old one.  */

static void
relate_alias_sets (tree gnu_new_type, tree gnu_old_type, enum alias_set_op op)
{
  /* Remove any padding from GNU_OLD_TYPE.  It doesn't matter in the case
     of a one-dimensional array, since the padding has the same alias set
     as the field type, but if it's a multi-dimensional array, we need to
     see the inner types.  */
  while (TREE_CODE (gnu_old_type) == RECORD_TYPE
         && (TYPE_JUSTIFIED_MODULAR_P (gnu_old_type)
             || TYPE_IS_PADDING_P (gnu_old_type)))
    gnu_old_type = TREE_TYPE (TYPE_FIELDS (gnu_old_type));

  /* Unconstrained array types are deemed incomplete and would thus be given
     alias set 0.  Retrieve the underlying array type.  */
  if (TREE_CODE (gnu_old_type) == UNCONSTRAINED_ARRAY_TYPE)
    gnu_old_type
      = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_old_type))));
  if (TREE_CODE (gnu_new_type) == UNCONSTRAINED_ARRAY_TYPE)
    gnu_new_type
      = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_new_type))));

  if (TREE_CODE (gnu_new_type) == ARRAY_TYPE
      && TREE_CODE (TREE_TYPE (gnu_new_type)) == ARRAY_TYPE
      && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_new_type)))
    relate_alias_sets (TREE_TYPE (gnu_new_type), TREE_TYPE (gnu_old_type), op);

  switch (op)
    {
    case ALIAS_SET_COPY:
      /* The alias set shouldn't be copied between array types with different
         aliasing settings because this can break the aliasing relationship
         between the array type and its element type.  */
#ifndef ENABLE_CHECKING
      if (flag_strict_aliasing)
#endif
        gcc_assert (!(TREE_CODE (gnu_new_type) == ARRAY_TYPE
                      && TREE_CODE (gnu_old_type) == ARRAY_TYPE
                      && TYPE_NONALIASED_COMPONENT (gnu_new_type)
                         != TYPE_NONALIASED_COMPONENT (gnu_old_type)));

      TYPE_ALIAS_SET (gnu_new_type) = get_alias_set (gnu_old_type);
      break;

    case ALIAS_SET_SUBSET:
    case ALIAS_SET_SUPERSET:
      {
        alias_set_type old_set = get_alias_set (gnu_old_type);
        alias_set_type new_set = get_alias_set (gnu_new_type);

        /* Do nothing if the alias sets conflict.  This ensures that we
           never call record_alias_subset several times for the same pair
           or at all for alias set 0.  */
        if (!alias_sets_conflict_p (old_set, new_set))
          {
            if (op == ALIAS_SET_SUBSET)
              record_alias_subset (old_set, new_set);
            else
              record_alias_subset (new_set, old_set);
          }
      }
      break;

    default:
      gcc_unreachable ();
    }

  record_component_aliases (gnu_new_type);
}
\f
/* Return a TREE_LIST describing the substitutions needed to reflect
   discriminant substitutions from GNAT_SUBTYPE to GNAT_TYPE and add
   them to GNU_LIST.  If GNAT_TYPE is not specified, use the base type
   of GNAT_SUBTYPE.  The substitutions can be in any order.  TREE_PURPOSE
   gives the tree for the discriminant and TREE_VALUES is the replacement
   value.  They are in the form of operands to substitute_in_expr.
   DEFINITION is as in gnat_to_gnu_entity.  */

static tree
substitution_list (Entity_Id gnat_subtype, Entity_Id gnat_type,
                   tree gnu_list, bool definition)
{
  Entity_Id gnat_discrim;
  Node_Id gnat_value;

  if (No (gnat_type))
    gnat_type = Implementation_Base_Type (gnat_subtype);

  if (Has_Discriminants (gnat_type))
    for (gnat_discrim = First_Stored_Discriminant (gnat_type),
         gnat_value = First_Elmt (Stored_Constraint (gnat_subtype));
         Present (gnat_discrim);
         gnat_discrim = Next_Stored_Discriminant (gnat_discrim),
         gnat_value = Next_Elmt (gnat_value))
      /* Ignore access discriminants.  */
      if (!Is_Access_Type (Etype (Node (gnat_value))))
        gnu_list = tree_cons (gnat_to_gnu_field_decl (gnat_discrim),
                              elaborate_expression
                              (Node (gnat_value), gnat_subtype,
                               get_entity_name (gnat_discrim), definition,
                               1, 0),
                              gnu_list);

  return gnu_list;
}
\f
/* Return true if the size represented by GNU_SIZE can be handled by an
   allocation.  If STATIC_P is true, consider only what can be done with a
   static allocation.  */

static bool
allocatable_size_p (tree gnu_size, bool static_p)
{
  HOST_WIDE_INT our_size;

  /* If this is not a static allocation, the only case we want to forbid
     is an overflowing size.  That will be converted into a raise a
     Storage_Error.  */
  if (!static_p)
    return !(TREE_CODE (gnu_size) == INTEGER_CST
             && TREE_OVERFLOW (gnu_size));

  /* Otherwise, we need to deal with both variable sizes and constant
     sizes that won't fit in a host int.  We use int instead of HOST_WIDE_INT
     since assemblers may not like very large sizes.  */
  if (!host_integerp (gnu_size, 1))
    return false;

  our_size = tree_low_cst (gnu_size, 1);
  return (int) our_size == our_size;
}
\f
/* Prepend to ATTR_LIST an entry for an attribute with provided TYPE,
   NAME, ARGS and ERROR_POINT.  */

static void
prepend_one_attribute_to (struct attrib ** attr_list,
                          enum attr_type attr_type,
                          tree attr_name,
                          tree attr_args,
                          Node_Id attr_error_point)
{
  struct attrib * attr = (struct attrib *) xmalloc (sizeof (struct attrib));

  attr->type = attr_type;
  attr->name = attr_name;
  attr->args = attr_args;
  attr->error_point = attr_error_point;

  attr->next = *attr_list;
  *attr_list = attr;
}

/* Prepend to ATTR_LIST the list of attributes for GNAT_ENTITY, if any.  */

static void
prepend_attributes (Entity_Id gnat_entity, struct attrib ** attr_list)
{
  Node_Id gnat_temp;

  for (gnat_temp = First_Rep_Item (gnat_entity); Present (gnat_temp);
       gnat_temp = Next_Rep_Item (gnat_temp))
    if (Nkind (gnat_temp) == N_Pragma)
      {
        tree gnu_arg0 = NULL_TREE, gnu_arg1 = NULL_TREE;
        Node_Id gnat_assoc = Pragma_Argument_Associations (gnat_temp);
        enum attr_type etype;

        if (Present (gnat_assoc) && Present (First (gnat_assoc))
            && Present (Next (First (gnat_assoc)))
            && (Nkind (Expression (Next (First (gnat_assoc))))
                == N_String_Literal))
          {
            gnu_arg0 = get_identifier (TREE_STRING_POINTER
                                       (gnat_to_gnu
                                        (Expression (Next
                                                     (First (gnat_assoc))))));
            if (Present (Next (Next (First (gnat_assoc))))
                && (Nkind (Expression (Next (Next (First (gnat_assoc)))))
                    == N_String_Literal))
              gnu_arg1 = get_identifier (TREE_STRING_POINTER
                                         (gnat_to_gnu
                                          (Expression
                                           (Next (Next
                                                  (First (gnat_assoc)))))));
          }

        switch (Get_Pragma_Id (Chars (Pragma_Identifier (gnat_temp))))
          {
          case Pragma_Machine_Attribute:
            etype = ATTR_MACHINE_ATTRIBUTE;
            break;

          case Pragma_Linker_Alias:
            etype = ATTR_LINK_ALIAS;
            break;

          case Pragma_Linker_Section:
            etype = ATTR_LINK_SECTION;
            break;

          case Pragma_Linker_Constructor:
            etype = ATTR_LINK_CONSTRUCTOR;
            break;

          case Pragma_Linker_Destructor:
            etype = ATTR_LINK_DESTRUCTOR;
            break;

          case Pragma_Weak_External:
            etype = ATTR_WEAK_EXTERNAL;
            break;

          default:
            continue;
          }


        /* Prepend to the list now.  Make a list of the argument we might
           have, as GCC expects it.  */
        prepend_one_attribute_to
          (attr_list,
           etype, gnu_arg0,
           (gnu_arg1 != NULL_TREE)
           ? build_tree_list (NULL_TREE, gnu_arg1) : NULL_TREE,
           Present (Next (First (gnat_assoc)))
           ? Expression (Next (First (gnat_assoc))) : gnat_temp);
      }
}
\f
/* Called when we need to protect a variable object using a save_expr.  */

tree
maybe_variable (tree gnu_operand)
{
  if (TREE_CONSTANT (gnu_operand) || TREE_READONLY (gnu_operand)
      || TREE_CODE (gnu_operand) == SAVE_EXPR
      || TREE_CODE (gnu_operand) == NULL_EXPR)
    return gnu_operand;

  if (TREE_CODE (gnu_operand) == UNCONSTRAINED_ARRAY_REF)
    {
      tree gnu_result = build1 (UNCONSTRAINED_ARRAY_REF,
                                TREE_TYPE (gnu_operand),
                                variable_size (TREE_OPERAND (gnu_operand, 0)));

      TREE_READONLY (gnu_result) = TREE_STATIC (gnu_result)
        = TYPE_READONLY (TREE_TYPE (TREE_TYPE (gnu_operand)));
      return gnu_result;
    }
  else
    return variable_size (gnu_operand);
}
\f
/* Given a GNAT tree GNAT_EXPR, for an expression which is a value within a
   type definition (either a bound or a discriminant value) for GNAT_ENTITY,
   return the GCC tree to use for that expression.  GNU_NAME is the
   qualification to use if an external name is appropriate and DEFINITION is
   true if this is a definition of GNAT_ENTITY.  If NEED_VALUE is true, we
   need a result.  Otherwise, we are just elaborating this for side-effects.
   If NEED_DEBUG is true we need the symbol for debugging purposes even if it
   isn't needed for code generation.  */

static tree
elaborate_expression (Node_Id gnat_expr, Entity_Id gnat_entity,
                      tree gnu_name, bool definition, bool need_value,
                      bool need_debug)
{
  tree gnu_expr;

  /* If we already elaborated this expression (e.g., it was involved
     in the definition of a private type), use the old value.  */
  if (present_gnu_tree (gnat_expr))
    return get_gnu_tree (gnat_expr);

  /* If we don't need a value and this is static or a discriminant, we
     don't need to do anything.  */
  else if (!need_value
           && (Is_OK_Static_Expression (gnat_expr)
               || (Nkind (gnat_expr) == N_Identifier
                   && Ekind (Entity (gnat_expr)) == E_Discriminant)))
    return 0;

  /* Otherwise, convert this tree to its GCC equivalent.  */
  gnu_expr
    = elaborate_expression_1 (gnat_expr, gnat_entity, gnat_to_gnu (gnat_expr),
                              gnu_name, definition, need_debug);

  /* Save the expression in case we try to elaborate this entity again.  Since
     it's not a DECL, don't check it.  Don't save if it's a discriminant.  */
  if (!CONTAINS_PLACEHOLDER_P (gnu_expr))
    save_gnu_tree (gnat_expr, gnu_expr, true);

  return need_value ? gnu_expr : error_mark_node;
}

/* Similar, but take a GNU expression.  */

static tree
elaborate_expression_1 (Node_Id gnat_expr, Entity_Id gnat_entity,
                        tree gnu_expr, tree gnu_name, bool definition,
                        bool need_debug)
{
  tree gnu_decl = NULL_TREE;
  /* Skip any conversions and simple arithmetics to see if the expression
     is a read-only variable.
     ??? This really should remain read-only, but we have to think about
     the typing of the tree here.  */
  tree gnu_inner_expr
    = skip_simple_arithmetic (remove_conversions (gnu_expr, true));
  bool expr_global = Is_Public (gnat_entity) || global_bindings_p ();
  bool expr_variable;

  /* In most cases, we won't see a naked FIELD_DECL here because a
     discriminant reference will have been replaced with a COMPONENT_REF
     when the type is being elaborated.  However, there are some cases
     involving child types where we will.  So convert it to a COMPONENT_REF
     here.  We have to hope it will be at the highest level of the
     expression in these cases.  */
  if (TREE_CODE (gnu_expr) == FIELD_DECL)
    gnu_expr = build3 (COMPONENT_REF, TREE_TYPE (gnu_expr),
                       build0 (PLACEHOLDER_EXPR, DECL_CONTEXT (gnu_expr)),
                       gnu_expr, NULL_TREE);

  /* If GNU_EXPR is neither a placeholder nor a constant, nor a variable
     that is read-only, make a variable that is initialized to contain the
     bound when the package containing the definition is elaborated.  If
     this entity is defined at top level and a bound or discriminant value
     isn't a constant or a reference to a discriminant, replace the bound
     by the variable; otherwise use a SAVE_EXPR if needed.  Note that we
     rely here on the fact that an expression cannot contain both the
     discriminant and some other variable.  */

  expr_variable = (!CONSTANT_CLASS_P (gnu_expr)
                   && !(TREE_CODE (gnu_inner_expr) == VAR_DECL
                        && (TREE_READONLY (gnu_inner_expr)
                            || DECL_READONLY_ONCE_ELAB (gnu_inner_expr)))
                   && !CONTAINS_PLACEHOLDER_P (gnu_expr));

  /* If this is a static expression or contains a discriminant, we don't
     need the variable for debugging (and can't elaborate anyway if a
     discriminant).  */
  if (need_debug
      && (Is_OK_Static_Expression (gnat_expr)
          || CONTAINS_PLACEHOLDER_P (gnu_expr)))
    need_debug = false;

  /* Now create the variable if we need it.  */
  if (need_debug || (expr_variable && expr_global))
    gnu_decl
      = create_var_decl (create_concat_name (gnat_entity,
                                             IDENTIFIER_POINTER (gnu_name)),
                         NULL_TREE, TREE_TYPE (gnu_expr), gnu_expr,
                         !need_debug, Is_Public (gnat_entity),
                         !definition, false, NULL, gnat_entity);

  /* We only need to use this variable if we are in global context since GCC
     can do the right thing in the local case.  */
  if (expr_global && expr_variable)
    return gnu_decl;
  else if (!expr_variable)
    return gnu_expr;
  else
    return maybe_variable (gnu_expr);
}
\f
/* Create a record type that contains a SIZE bytes long field of TYPE with a
   starting bit position so that it is aligned to ALIGN bits, and leaving at
   least ROOM bytes free before the field.  BASE_ALIGN is the alignment the
   record is guaranteed to get.  */

tree
make_aligning_type (tree type, unsigned int align, tree size,
                    unsigned int base_align, int room)
{
  /* We will be crafting a record type with one field at a position set to be
     the next multiple of ALIGN past record'address + room bytes.  We use a
     record placeholder to express record'address.  */

  tree record_type = make_node (RECORD_TYPE);
  tree record = build0 (PLACEHOLDER_EXPR, record_type);

  tree record_addr_st
    = convert (sizetype, build_unary_op (ADDR_EXPR, NULL_TREE, record));

  /* The diagram below summarizes the shape of what we manipulate:

                    <--------- pos ---------->
                {  +------------+-------------+-----------------+
      record  =>{  |############|     ...     | field (type)    |
                {  +------------+-------------+-----------------+
                   |<-- room -->|<- voffset ->|<---- size ----->|
                   o            o
                   |            |
                   record_addr  vblock_addr

     Every length is in sizetype bytes there, except "pos" which has to be
     set as a bit position in the GCC tree for the record.  */

  tree room_st = size_int (room);
  tree vblock_addr_st = size_binop (PLUS_EXPR, record_addr_st, room_st);
  tree voffset_st, pos, field;

  tree name = TYPE_NAME (type);

  if (TREE_CODE (name) == TYPE_DECL)
    name = DECL_NAME (name);

  TYPE_NAME (record_type) = concat_id_with_name (name, "_ALIGN");

  /* Compute VOFFSET and then POS.  The next byte position multiple of some
     alignment after some address is obtained by "and"ing the alignment minus
     1 with the two's complement of the address.   */

  voffset_st = size_binop (BIT_AND_EXPR,
                           size_diffop (size_zero_node, vblock_addr_st),
                           ssize_int ((align / BITS_PER_UNIT) - 1));

  /* POS = (ROOM + VOFFSET) * BIT_PER_UNIT, in bitsizetype.  */

  pos = size_binop (MULT_EXPR,
                    convert (bitsizetype,
                             size_binop (PLUS_EXPR, room_st, voffset_st)),
                    bitsize_unit_node);

  /* Craft the GCC record representation.  We exceptionally do everything
     manually here because 1) our generic circuitry is not quite ready to
     handle the complex position/size expressions we are setting up, 2) we
     have a strong simplifying factor at hand: we know the maximum possible
     value of voffset, and 3) we have to set/reset at least the sizes in
     accordance with this maximum value anyway, as we need them to convey
     what should be "alloc"ated for this type.

     Use -1 as the 'addressable' indication for the field to prevent the
     creation of a bitfield.  We don't need one, it would have damaging
     consequences on the alignment computation, and create_field_decl would
     make one without this special argument, for instance because of the
     complex position expression.  */

  field = create_field_decl (get_identifier ("F"), type, record_type,
                             1, size, pos, -1);
  TYPE_FIELDS (record_type) = field;

  TYPE_ALIGN (record_type) = base_align;
  TYPE_USER_ALIGN (record_type) = 1;

  TYPE_SIZE (record_type)
    = size_binop (PLUS_EXPR,
                  size_binop (MULT_EXPR, convert (bitsizetype, size),
                              bitsize_unit_node),
                  bitsize_int (align + room * BITS_PER_UNIT));
  TYPE_SIZE_UNIT (record_type)
    = size_binop (PLUS_EXPR, size,
                  size_int (room + align / BITS_PER_UNIT));

  SET_TYPE_MODE (record_type, BLKmode);

  relate_alias_sets (record_type, type, ALIAS_SET_COPY);
  return record_type;
}
\f
/* Return the result of rounding T up to ALIGN.  */

static inline unsigned HOST_WIDE_INT
round_up_to_align (unsigned HOST_WIDE_INT t, unsigned int align)
{
  t += align - 1;
  t /= align;
  t *= align;
  return t;
}

/* TYPE is a RECORD_TYPE, UNION_TYPE or QUAL_UNION_TYPE that is being used
   as the field type of a packed record if IN_RECORD is true, or as the
   component type of a packed array if IN_RECORD is false.  See if we can
   rewrite it either as a type that has a non-BLKmode, which we can pack
   tighter in the packed record case, or as a smaller type.  If so, return
   the new type.  If not, return the original type.  */

static tree
make_packable_type (tree type, bool in_record)
{
  unsigned HOST_WIDE_INT size = tree_low_cst (TYPE_SIZE (type), 1);
  unsigned HOST_WIDE_INT new_size;
  tree new_type, old_field, field_list = NULL_TREE;

  /* No point in doing anything if the size is zero.  */
  if (size == 0)
    return type;

  new_type = make_node (TREE_CODE (type));

  /* Copy the name and flags from the old type to that of the new.
     Note that we rely on the pointer equality created here for
     TYPE_NAME to look through conversions in various places.  */
  TYPE_NAME (new_type) = TYPE_NAME (type);
  TYPE_JUSTIFIED_MODULAR_P (new_type) = TYPE_JUSTIFIED_MODULAR_P (type);
  TYPE_CONTAINS_TEMPLATE_P (new_type) = TYPE_CONTAINS_TEMPLATE_P (type);
  if (TREE_CODE (type) == RECORD_TYPE)
    TYPE_IS_PADDING_P (new_type) = TYPE_IS_PADDING_P (type);

  /* If we are in a record and have a small size, set the alignment to
     try for an integral mode.  Otherwise set it to try for a smaller
     type with BLKmode.  */
  if (in_record && size <= MAX_FIXED_MODE_SIZE)
    {
      TYPE_ALIGN (new_type) = ceil_alignment (size);
      new_size = round_up_to_align (size, TYPE_ALIGN (new_type));
    }
  else
    {
      unsigned HOST_WIDE_INT align;

      /* Do not try to shrink the size if the RM size is not constant.  */
      if (TYPE_CONTAINS_TEMPLATE_P (type)
          || !host_integerp (TYPE_ADA_SIZE (type), 1))
        return type;

      /* Round the RM size up to a unit boundary to get the minimal size
         for a BLKmode record.  Give up if it's already the size.  */
      new_size = TREE_INT_CST_LOW (TYPE_ADA_SIZE (type));
      new_size = round_up_to_align (new_size, BITS_PER_UNIT);
      if (new_size == size)
        return type;

      align = new_size & -new_size;
      TYPE_ALIGN (new_type) = MIN (TYPE_ALIGN (type), align);
    }

  TYPE_USER_ALIGN (new_type) = 1;

  /* Now copy the fields, keeping the position and size as we don't want
     to change the layout by propagating the packedness downwards.  */
  for (old_field = TYPE_FIELDS (type); old_field;
       old_field = TREE_CHAIN (old_field))
    {
      tree new_field_type = TREE_TYPE (old_field);
      tree new_field, new_size;

      if ((TREE_CODE (new_field_type) == RECORD_TYPE
           || TREE_CODE (new_field_type) == UNION_TYPE
           || TREE_CODE (new_field_type) == QUAL_UNION_TYPE)
          && !TYPE_IS_FAT_POINTER_P (new_field_type)
          && host_integerp (TYPE_SIZE (new_field_type), 1))
        new_field_type = make_packable_type (new_field_type, true);

      /* However, for the last field in a not already packed record type
         that is of an aggregate type, we need to use the RM_Size in the
         packable version of the record type, see finish_record_type.  */
      if (!TREE_CHAIN (old_field)
          && !TYPE_PACKED (type)
          && (TREE_CODE (new_field_type) == RECORD_TYPE
              || TREE_CODE (new_field_type) == UNION_TYPE
              || TREE_CODE (new_field_type) == QUAL_UNION_TYPE)
          && !TYPE_IS_FAT_POINTER_P (new_field_type)
          && !TYPE_CONTAINS_TEMPLATE_P (new_field_type)
          && TYPE_ADA_SIZE (new_field_type))
        new_size = TYPE_ADA_SIZE (new_field_type);
      else
        new_size = DECL_SIZE (old_field);

      new_field = create_field_decl (DECL_NAME (old_field), new_field_type,
                                     new_type, TYPE_PACKED (type), new_size,
                                     bit_position (old_field),
                                     !DECL_NONADDRESSABLE_P (old_field));

      DECL_INTERNAL_P (new_field) = DECL_INTERNAL_P (old_field);
      SET_DECL_ORIGINAL_FIELD
        (new_field, (DECL_ORIGINAL_FIELD (old_field)
                     ? DECL_ORIGINAL_FIELD (old_field) : old_field));

      if (TREE_CODE (new_type) == QUAL_UNION_TYPE)
        DECL_QUALIFIER (new_field) = DECL_QUALIFIER (old_field);

      TREE_CHAIN (new_field) = field_list;
      field_list = new_field;
    }

  finish_record_type (new_type, nreverse (field_list), 2, true);
  relate_alias_sets (new_type, type, ALIAS_SET_COPY);

  /* If this is a padding record, we never want to make the size smaller
     than what was specified.  For QUAL_UNION_TYPE, also copy the size.  */
  if ((TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
      || TREE_CODE (type) == QUAL_UNION_TYPE)
    {
      TYPE_SIZE (new_type) = TYPE_SIZE (type);
      TYPE_SIZE_UNIT (new_type) = TYPE_SIZE_UNIT (type);
    }
  else
    {
      TYPE_SIZE (new_type) = bitsize_int (new_size);
      TYPE_SIZE_UNIT (new_type)
        = size_int ((new_size + BITS_PER_UNIT - 1) / BITS_PER_UNIT);
    }

  if (!TYPE_CONTAINS_TEMPLATE_P (type))
    SET_TYPE_ADA_SIZE (new_type, TYPE_ADA_SIZE (type));

  compute_record_mode (new_type);

  /* Try harder to get a packable type if necessary, for example
     in case the record itself contains a BLKmode field.  */
  if (in_record && TYPE_MODE (new_type) == BLKmode)
    SET_TYPE_MODE (new_type,
                   mode_for_size_tree (TYPE_SIZE (new_type), MODE_INT, 1));

  /* If neither the mode nor the size has shrunk, return the old type.  */
  if (TYPE_MODE (new_type) == BLKmode && new_size >= size)
    return type;

  return new_type;
}
\f
/* Ensure that TYPE has SIZE and ALIGN.  Make and return a new padded type
   if needed.  We have already verified that SIZE and TYPE are large enough.

   GNAT_ENTITY and NAME_TRAILER are used to name the resulting record and
   to issue a warning.

   IS_USER_TYPE is true if we must complete the original type.

   DEFINITION is true if this type is being defined.

   SAME_RM_SIZE is true if the RM_Size of the resulting type is to be set
   to SIZE too; otherwise, it's set to the RM_Size of the original type.  */

tree
maybe_pad_type (tree type, tree size, unsigned int align,
                Entity_Id gnat_entity, const char *name_trailer,
                bool is_user_type, bool definition, bool same_rm_size)
{
  tree orig_rm_size = same_rm_size ? NULL_TREE : rm_size (type);
  tree orig_size = TYPE_SIZE (type);
  unsigned int orig_align = align;
  tree record, field;

  /* If TYPE is a padded type, see if it agrees with any size and alignment
     we were given.  If so, return the original type.  Otherwise, strip
     off the padding, since we will either be returning the inner type
     or repadding it.  If no size or alignment is specified, use that of
     the original padded type.  */
  if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
    {
      if ((!size
           || operand_equal_p (round_up (size,
                                         MAX (align, TYPE_ALIGN (type))),
                               round_up (TYPE_SIZE (type),
                                         MAX (align, TYPE_ALIGN (type))),
                               0))
          && (align == 0 || align == TYPE_ALIGN (type)))
        return type;

      if (!size)
        size = TYPE_SIZE (type);
      if (align == 0)
        align = TYPE_ALIGN (type);

      type = TREE_TYPE (TYPE_FIELDS (type));
      orig_size = TYPE_SIZE (type);
    }

  /* If the size is either not being changed or is being made smaller (which
     is not done here (and is only valid for bitfields anyway), show the size
     isn't changing.  Likewise, clear the alignment if it isn't being
     changed.  Then return if we aren't doing anything.  */
  if (size
      && (operand_equal_p (size, orig_size, 0)
          || (TREE_CODE (orig_size) == INTEGER_CST
              && tree_int_cst_lt (size, orig_size))))
    size = NULL_TREE;

  if (align == TYPE_ALIGN (type))
    align = 0;

  if (align == 0 && !size)
    return type;

  /* If requested, complete the original type and give it a name.  */
  if (is_user_type)
    create_type_decl (get_entity_name (gnat_entity), type,
                      NULL, !Comes_From_Source (gnat_entity),
                      !(TYPE_NAME (type)
                        && TREE_CODE (TYPE_NAME (type)) == TYPE_DECL
                        && DECL_IGNORED_P (TYPE_NAME (type))),
                      gnat_entity);

  /* We used to modify the record in place in some cases, but that could
     generate incorrect debugging information.  So make a new record
     type and name.  */
  record = make_node (RECORD_TYPE);
  TYPE_IS_PADDING_P (record) = 1;

  if (Present (gnat_entity))
    TYPE_NAME (record) = create_concat_name (gnat_entity, name_trailer);

  TYPE_VOLATILE (record)
    = Present (gnat_entity) && Treat_As_Volatile (gnat_entity);

  TYPE_ALIGN (record) = align;
  if (orig_align)
    TYPE_USER_ALIGN (record) = align;

  TYPE_SIZE (record) = size ? size : orig_size;
  TYPE_SIZE_UNIT (record)
    = convert (sizetype,
               size_binop (CEIL_DIV_EXPR, TYPE_SIZE (record),
                           bitsize_unit_node));

  /* If we are changing the alignment and the input type is a record with
     BLKmode and a small constant size, try to make a form that has an
     integral mode.  This might allow the padding record to also have an
     integral mode, which will be much more efficient.  There is no point
     in doing so if a size is specified unless it is also a small constant
     size and it is incorrect to do so if we cannot guarantee that the mode
     will be naturally aligned since the field must always be addressable.

     ??? This might not always be a win when done for a stand-alone object:
     since the nominal and the effective type of the object will now have
     different modes, a VIEW_CONVERT_EXPR will be required for converting
     between them and it might be hard to overcome afterwards, including
     at the RTL level when the stand-alone object is accessed as a whole.  */
  if (align != 0
      && TREE_CODE (type) == RECORD_TYPE
      && TYPE_MODE (type) == BLKmode
      && TREE_CODE (orig_size) == INTEGER_CST
      && !TREE_OVERFLOW (orig_size)
      && compare_tree_int (orig_size, MAX_FIXED_MODE_SIZE) <= 0
      && (!size
          || (TREE_CODE (size) == INTEGER_CST
              && compare_tree_int (size, MAX_FIXED_MODE_SIZE) <= 0)))
    {
      tree packable_type = make_packable_type (type, true);
      if (TYPE_MODE (packable_type) != BLKmode
          && align >= TYPE_ALIGN (packable_type))
        type = packable_type;
    }

  /* Now create the field with the original size.  */
  field  = create_field_decl (get_identifier ("F"), type, record, 0,
                              orig_size, bitsize_zero_node, 1);
  DECL_INTERNAL_P (field) = 1;

  /* Do not finalize it until after the auxiliary record is built.  */
  finish_record_type (record, field, 1, true);

  /* Set the same size for its RM_size if requested; otherwise reuse
     the RM_size of the original type.  */
  SET_TYPE_ADA_SIZE (record, same_rm_size ? size : orig_rm_size);

  /* Unless debugging information isn't being written for the input type,
     write a record that shows what we are a subtype of and also make a
     variable that indicates our size, if still variable.  */
  if (TYPE_NAME (record)
      && AGGREGATE_TYPE_P (type)
      && TREE_CODE (orig_size) != INTEGER_CST
      && !(TREE_CODE (TYPE_NAME (type)) == TYPE_DECL
           && DECL_IGNORED_P (TYPE_NAME (type))))
    {
      tree marker = make_node (RECORD_TYPE);
      tree name = TYPE_NAME (record);
      tree orig_name = TYPE_NAME (type);

      if (TREE_CODE (name) == TYPE_DECL)
        name = DECL_NAME (name);

      if (TREE_CODE (orig_name) == TYPE_DECL)
        orig_name = DECL_NAME (orig_name);

      TYPE_NAME (marker) = concat_id_with_name (name, "XVS");
      finish_record_type (marker,
                          create_field_decl (orig_name, integer_type_node,
                                             marker, 0, NULL_TREE, NULL_TREE,
                                             0),
                          0, false);

      add_parallel_type (TYPE_STUB_DECL (record), marker);

      if (size && TREE_CODE (size) != INTEGER_CST && definition)
        create_var_decl (concat_id_with_name (name, "XVZ"), NULL_TREE,
                         sizetype, TYPE_SIZE_UNIT (record), false, false,
                         false, false, NULL, gnat_entity);
    }

  rest_of_record_type_compilation (record);

  /* If the size was widened explicitly, maybe give a warning.  Take the
     original size as the maximum size of the input if there was an
     unconstrained record involved and round it up to the specified alignment,
     if one was specified.  */
  if (CONTAINS_PLACEHOLDER_P (orig_size))
    orig_size = max_size (orig_size, true);

  if (align)
    orig_size = round_up (orig_size, align);

  if (size && Present (gnat_entity)
      && !operand_equal_p (size, orig_size, 0)
      && !(TREE_CODE (size) == INTEGER_CST
           && TREE_CODE (orig_size) == INTEGER_CST
           && tree_int_cst_lt (size, orig_size)))
    {
      Node_Id gnat_error_node = Empty;

      if (Is_Packed_Array_Type (gnat_entity))
        gnat_entity = Original_Array_Type (gnat_entity);

      if ((Ekind (gnat_entity) == E_Component
           || Ekind (gnat_entity) == E_Discriminant)
          && Present (Component_Clause (gnat_entity)))
        gnat_error_node = Last_Bit (Component_Clause (gnat_entity));
      else if (Present (Size_Clause (gnat_entity)))
        gnat_error_node = Expression (Size_Clause (gnat_entity));

      /* Generate message only for entities that come from source, since
         if we have an entity created by expansion, the message will be
         generated for some other corresponding source entity.  */
      if (Comes_From_Source (gnat_entity) && Present (gnat_error_node))
        post_error_ne_tree ("{^ }bits of & unused?", gnat_error_node,
                            gnat_entity,
                            size_diffop (size, orig_size));

      else if (*name_trailer == 'C' && !Is_Internal (gnat_entity))
        post_error_ne_tree ("component of& padded{ by ^ bits}?",
                            gnat_entity, gnat_entity,
                            size_diffop (size, orig_size));
    }

  return record;
}
\f
/* Given a GNU tree and a GNAT list of choices, generate an expression to test
   the value passed against the list of choices.  */

tree
choices_to_gnu (tree operand, Node_Id choices)
{
  Node_Id choice;
  Node_Id gnat_temp;
  tree result = integer_zero_node;
  tree this_test, low = 0, high = 0, single = 0;

  for (choice = First (choices); Present (choice); choice = Next (choice))
    {
      switch (Nkind (choice))
        {
        case N_Range:
          low = gnat_to_gnu (Low_Bound (choice));
          high = gnat_to_gnu (High_Bound (choice));

          /* There's no good type to use here, so we might as well use
             integer_type_node.  */
          this_test
            = build_binary_op (TRUTH_ANDIF_EXPR, integer_type_node,
                               build_binary_op (GE_EXPR, integer_type_node,
                                                operand, low),
                               build_binary_op (LE_EXPR, integer_type_node,
                                                operand, high));

          break;

        case N_Subtype_Indication:
          gnat_temp = Range_Expression (Constraint (choice));
          low = gnat_to_gnu (Low_Bound (gnat_temp));
          high = gnat_to_gnu (High_Bound (gnat_temp));

          this_test
            = build_binary_op (TRUTH_ANDIF_EXPR, integer_type_node,
                               build_binary_op (GE_EXPR, integer_type_node,
                                                operand, low),
                               build_binary_op (LE_EXPR, integer_type_node,
                                                operand, high));
          break;

        case N_Identifier:
        case N_Expanded_Name:
          /* This represents either a subtype range, an enumeration
             literal, or a constant  Ekind says which.  If an enumeration
             literal or constant, fall through to the next case.  */
          if (Ekind (Entity (choice)) != E_Enumeration_Literal
              && Ekind (Entity (choice)) != E_Constant)
            {
              tree type = gnat_to_gnu_type (Entity (choice));

              low = TYPE_MIN_VALUE (type);
              high = TYPE_MAX_VALUE (type);

              this_test
                = build_binary_op (TRUTH_ANDIF_EXPR, integer_type_node,
                                   build_binary_op (GE_EXPR, integer_type_node,
                                                    operand, low),
                                   build_binary_op (LE_EXPR, integer_type_node,
                                                    operand, high));
              break;
            }

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

        case N_Character_Literal:
        case N_Integer_Literal:
          single = gnat_to_gnu (choice);
          this_test = build_binary_op (EQ_EXPR, integer_type_node, operand,
                                       single);
          break;

        case N_Others_Choice:
          this_test = integer_one_node;
          break;

        default:
          gcc_unreachable ();
        }

      result = build_binary_op (TRUTH_ORIF_EXPR, integer_type_node,
                                result, this_test);
    }

  return result;
}
\f
/* Adjust PACKED setting as passed to gnat_to_gnu_field for a field of
   type FIELD_TYPE to be placed in RECORD_TYPE.  Return the result.  */

static int
adjust_packed (tree field_type, tree record_type, int packed)
{
  /* If the field contains an item of variable size, we cannot pack it
     because we cannot create temporaries of non-fixed size in case
     we need to take the address of the field.  See addressable_p and
     the notes on the addressability issues for further details.  */
  if (is_variable_size (field_type))
    return 0;

  /* If the alignment of the record is specified and the field type
     is over-aligned, request Storage_Unit alignment for the field.  */
  if (packed == -2)
    {
      if (TYPE_ALIGN (field_type) > TYPE_ALIGN (record_type))
        return -1;
      else
        return 0;
    }

  return packed;
}

/* Return a GCC tree for a field corresponding to GNAT_FIELD to be
   placed in GNU_RECORD_TYPE.

   PACKED is 1 if the enclosing record is packed, -1 if the enclosing
   record has Component_Alignment of Storage_Unit, -2 if the enclosing
   record has a specified alignment.

   DEFINITION is true if this field is for a record being defined.  */

static tree
gnat_to_gnu_field (Entity_Id gnat_field, tree gnu_record_type, int packed,
                   bool definition)
{
  tree gnu_field_id = get_entity_name (gnat_field);
  tree gnu_field_type = gnat_to_gnu_type (Etype (gnat_field));
  tree gnu_field, gnu_size, gnu_pos;
  bool needs_strict_alignment
    = (Is_Aliased (gnat_field) || Strict_Alignment (Etype (gnat_field))
       || Treat_As_Volatile (gnat_field));

  /* If this field requires strict alignment, we cannot pack it because
     it would very likely be under-aligned in the record.  */
  if (needs_strict_alignment)
    packed = 0;
  else
    packed = adjust_packed (gnu_field_type, gnu_record_type, packed);

  /* If a size is specified, use it.  Otherwise, if the record type is packed,
     use the official RM size.  See "Handling of Type'Size Values" in Einfo
     for further details.  */
  if (Known_Static_Esize (gnat_field))
    gnu_size = validate_size (Esize (gnat_field), gnu_field_type,
                              gnat_field, FIELD_DECL, false, true);
  else if (packed == 1)
    gnu_size = validate_size (RM_Size (Etype (gnat_field)), gnu_field_type,
                              gnat_field, FIELD_DECL, false, true);
  else
    gnu_size = NULL_TREE;

  /* If we have a specified size that's smaller than that of the field type,
     or a position is specified, and the field type is a record, see if we can
     get either an integral mode form of the type or a smaller form.  If we
     can, show a size was specified for the field if there wasn't one already,
     so we know to make this a bitfield and avoid making things wider.

     Doing this is first useful if the record is packed because we may then
     place the field at a non-byte-aligned position and so achieve tighter
     packing.

     This is in addition *required* if the field shares a byte with another
     field and the front-end lets the back-end handle the references, because
     GCC does not handle BLKmode bitfields properly.

     We avoid the transformation if it is not required or potentially useful,
     as it might entail an increase of the field's alignment and have ripple
     effects on the outer record type.  A typical case is a field known to be
     byte aligned and not to share a byte with another field.

     Besides, we don't even look the possibility of a transformation in cases
     known to be in error already, for instance when an invalid size results
     from a component clause.  */

  if (TREE_CODE (gnu_field_type) == RECORD_TYPE
      && !TYPE_IS_FAT_POINTER_P (gnu_field_type)
      && host_integerp (TYPE_SIZE (gnu_field_type), 1)
      && (packed == 1
          || (gnu_size
              && (tree_int_cst_lt (gnu_size, TYPE_SIZE (gnu_field_type))
                  || Present (Component_Clause (gnat_field))))))
    {
      /* See what the alternate type and size would be.  */
      tree gnu_packable_type = make_packable_type (gnu_field_type, true);

      bool has_byte_aligned_clause
        = Present (Component_Clause (gnat_field))
          && (UI_To_Int (Component_Bit_Offset (gnat_field))
              % BITS_PER_UNIT == 0);

      /* Compute whether we should avoid the substitution.  */
      bool reject
        /* There is no point substituting if there is no change...  */
        = (gnu_packable_type == gnu_field_type)
         /* ... nor when the field is known to be byte aligned and not to
            share a byte with another field.  */
          || (has_byte_aligned_clause
              && value_factor_p (gnu_size, BITS_PER_UNIT))
         /* The size of an aliased field must be an exact multiple of the
            type's alignment, which the substitution might increase.  Reject
            substitutions that would so invalidate a component clause when the
            specified position is byte aligned, as the change would have no
            real benefit from the packing standpoint anyway.  */
          || (Is_Aliased (gnat_field)
              && has_byte_aligned_clause
              && !value_factor_p (gnu_size, TYPE_ALIGN (gnu_packable_type)));

      /* Substitute unless told otherwise.  */
      if (!reject)
        {
          gnu_field_type = gnu_packable_type;

          if (!gnu_size)
            gnu_size = rm_size (gnu_field_type);
        }
    }

  /* If we are packing the record and the field is BLKmode, round the
     size up to a byte boundary.  */
  if (packed && TYPE_MODE (gnu_field_type) == BLKmode && gnu_size)
    gnu_size = round_up (gnu_size, BITS_PER_UNIT);

  if (Present (Component_Clause (gnat_field)))
    {
      gnu_pos = UI_To_gnu (Component_Bit_Offset (gnat_field), bitsizetype);
      gnu_size = validate_size (Esize (gnat_field), gnu_field_type,
                                gnat_field, FIELD_DECL, false, true);

      /* Ensure the position does not overlap with the parent subtype,
         if there is one.  */
      if (Present (Parent_Subtype (Underlying_Type (Scope (gnat_field)))))
        {
          tree gnu_parent
            = gnat_to_gnu_type (Parent_Subtype
                                (Underlying_Type (Scope (gnat_field))));

          if (TREE_CODE (TYPE_SIZE (gnu_parent)) == INTEGER_CST
              && tree_int_cst_lt (gnu_pos, TYPE_SIZE (gnu_parent)))
            {
              post_error_ne_tree
                ("offset of& must be beyond parent{, minimum allowed is ^}",
                 First_Bit (Component_Clause (gnat_field)), gnat_field,
                 TYPE_SIZE_UNIT (gnu_parent));
            }
        }

      /* If this field needs strict alignment, ensure the record is
         sufficiently aligned and that that position and size are
         consistent with the alignment.  */
      if (needs_strict_alignment)
        {
          TYPE_ALIGN (gnu_record_type)
            = MAX (TYPE_ALIGN (gnu_record_type), TYPE_ALIGN (gnu_field_type));

          if (gnu_size
              && !operand_equal_p (gnu_size, TYPE_SIZE (gnu_field_type), 0))
            {
              if (Is_Atomic (gnat_field) || Is_Atomic (Etype (gnat_field)))
                post_error_ne_tree
                  ("atomic field& must be natural size of type{ (^)}",
                   Last_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_SIZE (gnu_field_type));

              else if (Is_Aliased (gnat_field))
                post_error_ne_tree
                  ("size of aliased field& must be ^ bits",
                   Last_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_SIZE (gnu_field_type));

              else if (Strict_Alignment (Etype (gnat_field)))
                post_error_ne_tree
                  ("size of & with aliased or tagged components not ^ bits",
                   Last_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_SIZE (gnu_field_type));

              gnu_size = NULL_TREE;
            }

          if (!integer_zerop (size_binop
                              (TRUNC_MOD_EXPR, gnu_pos,
                               bitsize_int (TYPE_ALIGN (gnu_field_type)))))
            {
              if (Is_Aliased (gnat_field))
                post_error_ne_num
                  ("position of aliased field& must be multiple of ^ bits",
                   First_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_ALIGN (gnu_field_type));

              else if (Treat_As_Volatile (gnat_field))
                post_error_ne_num
                  ("position of volatile field& must be multiple of ^ bits",
                   First_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_ALIGN (gnu_field_type));

              else if (Strict_Alignment (Etype (gnat_field)))
                post_error_ne_num
  ("position of & with aliased or tagged components not multiple of ^ bits",
                   First_Bit (Component_Clause (gnat_field)), gnat_field,
                   TYPE_ALIGN (gnu_field_type));

              else
                gcc_unreachable ();

              gnu_pos = NULL_TREE;
            }
        }

      if (Is_Atomic (gnat_field))
        check_ok_for_atomic (gnu_field_type, gnat_field, false);
    }

  /* If the record has rep clauses and this is the tag field, make a rep
     clause for it as well.  */
  else if (Has_Specified_Layout (Scope (gnat_field))
           && Chars (gnat_field) == Name_uTag)
    {
      gnu_pos = bitsize_zero_node;
      gnu_size = TYPE_SIZE (gnu_field_type);
    }

  else
    gnu_pos = NULL_TREE;

  /* We need to make the size the maximum for the type if it is
     self-referential and an unconstrained type.  In that case, we can't
     pack the field since we can't make a copy to align it.  */
  if (TREE_CODE (gnu_field_type) == RECORD_TYPE
      && !gnu_size
      && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_field_type))
      && !Is_Constrained (Underlying_Type (Etype (gnat_field))))
    {
      gnu_size = max_size (TYPE_SIZE (gnu_field_type), true);
      packed = 0;
    }

  /* If a size is specified, adjust the field's type to it.  */
  if (gnu_size)
    {
      /* If the field's type is justified modular, we would need to remove
         the wrapper to (better) meet the layout requirements.  However we
         can do so only if the field is not aliased to preserve the unique
         layout and if the prescribed size is not greater than that of the
         packed array to preserve the justification.  */
      if (!needs_strict_alignment
          && TREE_CODE (gnu_field_type) == RECORD_TYPE
          && TYPE_JUSTIFIED_MODULAR_P (gnu_field_type)
          && tree_int_cst_compare (gnu_size, TYPE_ADA_SIZE (gnu_field_type))
               <= 0)
        gnu_field_type = TREE_TYPE (TYPE_FIELDS (gnu_field_type));

      gnu_field_type
        = make_type_from_size (gnu_field_type, gnu_size,
                               Has_Biased_Representation (gnat_field));
      gnu_field_type = maybe_pad_type (gnu_field_type, gnu_size, 0, gnat_field,
                                       "PAD", false, definition, true);
    }

  /* Otherwise (or if there was an error), don't specify a position.  */
  else
    gnu_pos = NULL_TREE;

  gcc_assert (TREE_CODE (gnu_field_type) != RECORD_TYPE
              || !TYPE_CONTAINS_TEMPLATE_P (gnu_field_type));

  /* Now create the decl for the field.  */
  gnu_field = create_field_decl (gnu_field_id, gnu_field_type, gnu_record_type,
                                 packed, gnu_size, gnu_pos,
                                 Is_Aliased (gnat_field));
  Sloc_to_locus (Sloc (gnat_field), &DECL_SOURCE_LOCATION (gnu_field));
  TREE_THIS_VOLATILE (gnu_field) = Treat_As_Volatile (gnat_field);

  if (Ekind (gnat_field) == E_Discriminant)
    DECL_DISCRIMINANT_NUMBER (gnu_field)
      = UI_To_gnu (Discriminant_Number (gnat_field), sizetype);

  return gnu_field;
}
\f
/* Return true if TYPE is a type with variable size, a padding type with a
   field of variable size or is a record that has a field such a field.  */

static bool
is_variable_size (tree type)
{
  tree field;

  if (!TREE_CONSTANT (TYPE_SIZE (type)))
    return true;

  if (TREE_CODE (type) == RECORD_TYPE
      && TYPE_IS_PADDING_P (type)
      && !TREE_CONSTANT (DECL_SIZE (TYPE_FIELDS (type))))
    return true;

  if (TREE_CODE (type) != RECORD_TYPE
      && TREE_CODE (type) != UNION_TYPE
      && TREE_CODE (type) != QUAL_UNION_TYPE)
    return false;

  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
    if (is_variable_size (TREE_TYPE (field)))
      return true;

  return false;
}
\f
/* qsort comparer for the bit positions of two record components.  */

static int
compare_field_bitpos (const PTR rt1, const PTR rt2)
{
  const_tree const field1 = * (const_tree const *) rt1;
  const_tree const field2 = * (const_tree const *) rt2;
  const int ret
    = tree_int_cst_compare (bit_position (field1), bit_position (field2));

  return ret ? ret : (int) (DECL_UID (field1) - DECL_UID (field2));
}

/* Return a GCC tree for a record type given a GNAT Component_List and a chain
   of GCC trees for fields that are in the record and have already been
   processed.  When called from gnat_to_gnu_entity during the processing of a
   record type definition, the GCC nodes for the discriminants will be on
   the chain.  The other calls to this function are recursive calls from
   itself for the Component_List of a variant and the chain is empty.

   PACKED is 1 if this is for a packed record, -1 if this is for a record
   with Component_Alignment of Storage_Unit, -2 if this is for a record
   with a specified alignment.

   DEFINITION is true if we are defining this record.

   P_GNU_REP_LIST, if nonzero, is a pointer to a list to which each field
   with a rep clause is to be added.  If it is nonzero, that is all that
   should be done with such fields.

   CANCEL_ALIGNMENT, if true, means the alignment should be zeroed before
   laying out the record.  This means the alignment only serves to force fields
   to be bitfields, but not require the record to be that aligned.  This is
   used for variants.

   ALL_REP, if true, means a rep clause was found for all the fields.  This
   simplifies the logic since we know we're not in the mixed case.

   DO_NOT_FINALIZE, if true, means that the record type is expected to be
   modified afterwards so it will not be sent to the back-end for finalization.

   UNCHECKED_UNION, if true, means that we are building a type for a record
   with a Pragma Unchecked_Union.

   The processing of the component list fills in the chain with all of the
   fields of the record and then the record type is finished.  */

static void
components_to_record (tree gnu_record_type, Node_Id component_list,
                      tree gnu_field_list, int packed, bool definition,
                      tree *p_gnu_rep_list, bool cancel_alignment,
                      bool all_rep, bool do_not_finalize, bool unchecked_union)
{
  Node_Id component_decl;
  Entity_Id gnat_field;
  Node_Id variant_part;
  tree gnu_our_rep_list = NULL_TREE;
  tree gnu_field, gnu_last;
  bool layout_with_rep = false;
  bool all_rep_and_size = all_rep && TYPE_SIZE (gnu_record_type);

  /* For each variable within each component declaration create a GCC field
     and add it to the list, skipping any pragmas in the list.  */
  if (Present (Component_Items (component_list)))
    for (component_decl = First_Non_Pragma (Component_Items (component_list));
         Present (component_decl);
         component_decl = Next_Non_Pragma (component_decl))
      {
        gnat_field = Defining_Entity (component_decl);

        if (Chars (gnat_field) == Name_uParent)
          gnu_field = tree_last (TYPE_FIELDS (gnu_record_type));
        else
          {
            gnu_field = gnat_to_gnu_field (gnat_field, gnu_record_type,
                                           packed, definition);

            /* If this is the _Tag field, put it before any discriminants,
               instead of after them as is the case for all other fields.  */
            if (Chars (gnat_field) == Name_uTag)
              gnu_field_list = chainon (gnu_field_list, gnu_field);
            else
              {
                TREE_CHAIN (gnu_field) = gnu_field_list;
                gnu_field_list = gnu_field;
              }
          }

        save_gnu_tree (gnat_field, gnu_field, false);
      }

  /* At the end of the component list there may be a variant part.  */
  variant_part = Variant_Part (component_list);

  /* We create a QUAL_UNION_TYPE for the variant part since the variants are
     mutually exclusive and should go in the same memory.  To do this we need
     to treat each variant as a record whose elements are created from the
     component list for the variant.  So here we create the records from the
     lists for the variants and put them all into the QUAL_UNION_TYPE.
     If this is an Unchecked_Union, we make a UNION_TYPE instead or
     use GNU_RECORD_TYPE if there are no fields so far.  */
  if (Present (variant_part))
    {
      tree gnu_discriminant = gnat_to_gnu (Name (variant_part));
      Node_Id variant;
      tree gnu_name = TYPE_NAME (gnu_record_type);
      tree gnu_var_name
        = concat_id_with_name (get_identifier (Get_Name_String
                                               (Chars (Name (variant_part)))),
                               "XVN");
      tree gnu_union_type;
      tree gnu_union_name;
      tree gnu_union_field;
      tree gnu_variant_list = NULL_TREE;

      if (TREE_CODE (gnu_name) == TYPE_DECL)
        gnu_name = DECL_NAME (gnu_name);

      gnu_union_name = concat_id_with_name (gnu_name,
                                            IDENTIFIER_POINTER (gnu_var_name));

      /* Reuse an enclosing union if all fields are in the variant part
         and there is no representation clause on the record, to match
         the layout of C unions.  There is an associated check below.  */
      if (!gnu_field_list
          && TREE_CODE (gnu_record_type) == UNION_TYPE
          && !TYPE_PACKED (gnu_record_type))
        gnu_union_type = gnu_record_type;
      else
        {
          gnu_union_type
            = make_node (unchecked_union ? UNION_TYPE : QUAL_UNION_TYPE);

          TYPE_NAME (gnu_union_type) = gnu_union_name;
          TYPE_ALIGN (gnu_union_type) = 0;
          TYPE_PACKED (gnu_union_type) = TYPE_PACKED (gnu_record_type);
        }

      for (variant = First_Non_Pragma (Variants (variant_part));
           Present (variant);
           variant = Next_Non_Pragma (variant))
        {
          tree gnu_variant_type = make_node (RECORD_TYPE);
          tree gnu_inner_name;
          tree gnu_qual;

          Get_Variant_Encoding (variant);
          gnu_inner_name = get_identifier (Name_Buffer);
          TYPE_NAME (gnu_variant_type)
            = concat_id_with_name (gnu_union_name,
                                   IDENTIFIER_POINTER (gnu_inner_name));

          /* Set the alignment of the inner type in case we need to make
             inner objects into bitfields, but then clear it out
             so the record actually gets only the alignment required.  */
          TYPE_ALIGN (gnu_variant_type) = TYPE_ALIGN (gnu_record_type);
          TYPE_PACKED (gnu_variant_type) = TYPE_PACKED (gnu_record_type);

          /* Similarly, if the outer record has a size specified and all fields
             have record rep clauses, we can propagate the size into the
             variant part.  */
          if (all_rep_and_size)
            {
              TYPE_SIZE (gnu_variant_type) = TYPE_SIZE (gnu_record_type);
              TYPE_SIZE_UNIT (gnu_variant_type)
                = TYPE_SIZE_UNIT (gnu_record_type);
            }

          /* Create the record type for the variant.  Note that we defer
             finalizing it until after we are sure to actually use it.  */
          components_to_record (gnu_variant_type, Component_List (variant),
                                NULL_TREE, packed, definition,
                                &gnu_our_rep_list, !all_rep_and_size, all_rep,
                                true, unchecked_union);

          gnu_qual = choices_to_gnu (gnu_discriminant,
                                     Discrete_Choices (variant));

          Set_Present_Expr (variant, annotate_value (gnu_qual));

          /* If this is an Unchecked_Union and we have exactly one field,
             use this field directly to match the layout of C unions.  */
          if (unchecked_union
              && TYPE_FIELDS (gnu_variant_type)
              && !TREE_CHAIN (TYPE_FIELDS (gnu_variant_type)))
            gnu_field = TYPE_FIELDS (gnu_variant_type);
          else
            {
              /* Deal with packedness like in gnat_to_gnu_field.  */
              int field_packed
                = adjust_packed (gnu_variant_type, gnu_record_type, packed);

              /* Finalize the record type now.  We used to throw away
                 empty records but we no longer do that because we need
                 them to generate complete debug info for the variant;
                 otherwise, the union type definition will be lacking
                 the fields associated with these empty variants.  */
              rest_of_record_type_compilation (gnu_variant_type);

              gnu_field = create_field_decl (gnu_inner_name, gnu_variant_type,
                                             gnu_union_type, field_packed,
                                             (all_rep_and_size
                                              ? TYPE_SIZE (gnu_variant_type)
                                              : 0),
                                             (all_rep_and_size
                                              ? bitsize_zero_node : 0),
                                             0);

              DECL_INTERNAL_P (gnu_field) = 1;

              if (!unchecked_union)
                DECL_QUALIFIER (gnu_field) = gnu_qual;
            }

          TREE_CHAIN (gnu_field) = gnu_variant_list;
          gnu_variant_list = gnu_field;
        }

      /* Only make the QUAL_UNION_TYPE if there are any non-empty variants.  */
      if (gnu_variant_list)
        {
          int union_field_packed;

          if (all_rep_and_size)
            {
              TYPE_SIZE (gnu_union_type) = TYPE_SIZE (gnu_record_type);
              TYPE_SIZE_UNIT (gnu_union_type)
                = TYPE_SIZE_UNIT (gnu_record_type);
            }

          finish_record_type (gnu_union_type, nreverse (gnu_variant_list),
                              all_rep_and_size ? 1 : 0, false);

          /* If GNU_UNION_TYPE is our record type, it means we must have an
             Unchecked_Union with no fields.  Verify that and, if so, just
             return.  */
          if (gnu_union_type == gnu_record_type)
            {
              gcc_assert (unchecked_union
                          && !gnu_field_list
                          && !gnu_our_rep_list);
              return;
            }

          /* Deal with packedness like in gnat_to_gnu_field.  */
          union_field_packed
            = adjust_packed (gnu_union_type, gnu_record_type, packed);

          gnu_union_field
            = create_field_decl (gnu_var_name, gnu_union_type, gnu_record_type,
                                 union_field_packed,
                                 all_rep ? TYPE_SIZE (gnu_union_type) : 0,
                                 all_rep ? bitsize_zero_node : 0, 0);

          DECL_INTERNAL_P (gnu_union_field) = 1;
          TREE_CHAIN (gnu_union_field) = gnu_field_list;
          gnu_field_list = gnu_union_field;
        }
    }

  /* Scan GNU_FIELD_LIST and see if any fields have rep clauses.  If they
     do, pull them out and put them into GNU_OUR_REP_LIST.  We have to do this
     in a separate pass since we want to handle the discriminants but can't
     play with them until we've used them in debugging data above.

     ??? Note: if we then reorder them, debugging information will be wrong,
     but there's nothing that can be done about this at the moment.  */
  for (gnu_field = gnu_field_list, gnu_last = NULL_TREE; gnu_field; )
    {
      if (DECL_FIELD_OFFSET (gnu_field))
        {
          tree gnu_next = TREE_CHAIN (gnu_field);

          if (!gnu_last)
            gnu_field_list = gnu_next;
          else
            TREE_CHAIN (gnu_last) = gnu_next;

          TREE_CHAIN (gnu_field) = gnu_our_rep_list;
          gnu_our_rep_list = gnu_field;
          gnu_field = gnu_next;
        }
      else
        {
          gnu_last = gnu_field;
          gnu_field = TREE_CHAIN (gnu_field);
        }
    }

  /* If we have any items in our rep'ed field list, it is not the case that all
     the fields in the record have rep clauses, and P_REP_LIST is nonzero,
     set it and ignore the items.  */
  if (gnu_our_rep_list && p_gnu_rep_list && !all_rep)
    *p_gnu_rep_list = chainon (*p_gnu_rep_list, gnu_our_rep_list);
  else if (gnu_our_rep_list)
    {
      /* Otherwise, sort the fields by bit position and put them into their
         own record if we have any fields without rep clauses.  */
      tree gnu_rep_type
        = (gnu_field_list ? make_node (RECORD_TYPE) : gnu_record_type);
      int len = list_length (gnu_our_rep_list);
      tree *gnu_arr = (tree *) alloca (sizeof (tree) * len);
      int i;

      for (i = 0, gnu_field = gnu_our_rep_list; gnu_field;
           gnu_field = TREE_CHAIN (gnu_field), i++)
        gnu_arr[i] = gnu_field;

      qsort (gnu_arr, len, sizeof (tree), compare_field_bitpos);

      /* Put the fields in the list in order of increasing position, which
         means we start from the end.  */
      gnu_our_rep_list = NULL_TREE;
      for (i = len - 1; i >= 0; i--)
        {
          TREE_CHAIN (gnu_arr[i]) = gnu_our_rep_list;
          gnu_our_rep_list = gnu_arr[i];
          DECL_CONTEXT (gnu_arr[i]) = gnu_rep_type;
        }

      if (gnu_field_list)
        {
          finish_record_type (gnu_rep_type, gnu_our_rep_list, 1, false);
          gnu_field = create_field_decl (get_identifier ("REP"), gnu_rep_type,
                                         gnu_record_type, 0, 0, 0, 1);
          DECL_INTERNAL_P (gnu_field) = 1;
          gnu_field_list = chainon (gnu_field_list, gnu_field);
        }
      else
        {
          layout_with_rep = true;
          gnu_field_list = nreverse (gnu_our_rep_list);
        }
    }

  if (cancel_alignment)
    TYPE_ALIGN (gnu_record_type) = 0;

  finish_record_type (gnu_record_type, nreverse (gnu_field_list),
                      layout_with_rep ? 1 : 0, do_not_finalize);
}
\f
/* Given GNU_SIZE, a GCC tree representing a size, return a Uint to be
   placed into an Esize, Component_Bit_Offset, or Component_Size value
   in the GNAT tree.  */

static Uint
annotate_value (tree gnu_size)
{
  int len = TREE_CODE_LENGTH (TREE_CODE (gnu_size));
  TCode tcode;
  Node_Ref_Or_Val ops[3], ret;
  int i;
  int size;
  struct tree_int_map **h = NULL;

  /* See if we've already saved the value for this node.  */
  if (EXPR_P (gnu_size))
    {
      struct tree_int_map in;
      if (!annotate_value_cache)
        annotate_value_cache = htab_create_ggc (512, tree_int_map_hash,
                                                tree_int_map_eq, 0);
      in.base.from = gnu_size;
      h = (struct tree_int_map **)
            htab_find_slot (annotate_value_cache, &in, INSERT);

      if (*h)
        return (Node_Ref_Or_Val) (*h)->to;
    }

  /* If we do not return inside this switch, TCODE will be set to the
     code to use for a Create_Node operand and LEN (set above) will be
     the number of recursive calls for us to make.  */

  switch (TREE_CODE (gnu_size))
    {
    case INTEGER_CST:
      if (TREE_OVERFLOW (gnu_size))
        return No_Uint;

      /* This may have come from a conversion from some smaller type,
         so ensure this is in bitsizetype.  */
      gnu_size = convert (bitsizetype, gnu_size);

      /* For negative values, use NEGATE_EXPR of the supplied value.  */
      if (tree_int_cst_sgn (gnu_size) < 0)
        {
          /* The ridiculous code below is to handle the case of the largest
             negative integer.  */
          tree negative_size = size_diffop (bitsize_zero_node, gnu_size);
          bool adjust = false;
          tree temp;

          if (TREE_OVERFLOW (negative_size))
            {
              negative_size
                = size_binop (MINUS_EXPR, bitsize_zero_node,
                              size_binop (PLUS_EXPR, gnu_size,
                                          bitsize_one_node));
              adjust = true;
            }

          temp = build1 (NEGATE_EXPR, bitsizetype, negative_size);
          if (adjust)
            temp = build2 (MINUS_EXPR, bitsizetype, temp, bitsize_one_node);

          return annotate_value (temp);
        }

      if (!host_integerp (gnu_size, 1))
        return No_Uint;

      size = tree_low_cst (gnu_size, 1);

      /* This peculiar test is to make sure that the size fits in an int
         on machines where HOST_WIDE_INT is not "int".  */
      if (tree_low_cst (gnu_size, 1) == size)
        return UI_From_Int (size);
      else
        return No_Uint;

    case COMPONENT_REF:
      /* The only case we handle here is a simple discriminant reference.  */
      if (TREE_CODE (TREE_OPERAND (gnu_size, 0)) == PLACEHOLDER_EXPR
          && TREE_CODE (TREE_OPERAND (gnu_size, 1)) == FIELD_DECL
          && DECL_DISCRIMINANT_NUMBER (TREE_OPERAND (gnu_size, 1)))
        return Create_Node (Discrim_Val,
                            annotate_value (DECL_DISCRIMINANT_NUMBER
                                            (TREE_OPERAND (gnu_size, 1))),
                            No_Uint, No_Uint);
      else
        return No_Uint;

    CASE_CONVERT:   case NON_LVALUE_EXPR:
      return annotate_value (TREE_OPERAND (gnu_size, 0));

      /* Now just list the operations we handle.  */
    case COND_EXPR:             tcode = Cond_Expr; break;
    case PLUS_EXPR:             tcode = Plus_Expr; break;
    case MINUS_EXPR:            tcode = Minus_Expr; break;
    case MULT_EXPR:             tcode = Mult_Expr; break;
    case TRUNC_DIV_EXPR:        tcode = Trunc_Div_Expr; break;
    case CEIL_DIV_EXPR:         tcode = Ceil_Div_Expr; break;
    case FLOOR_DIV_EXPR:        tcode = Floor_Div_Expr; break;
    case TRUNC_MOD_EXPR:        tcode = Trunc_Mod_Expr; break;
    case CEIL_MOD_EXPR:         tcode = Ceil_Mod_Expr; break;
    case FLOOR_MOD_EXPR:        tcode = Floor_Mod_Expr; break;
    case EXACT_DIV_EXPR:        tcode = Exact_Div_Expr; break;
    case NEGATE_EXPR:           tcode = Negate_Expr; break;
    case MIN_EXPR:              tcode = Min_Expr; break;
    case MAX_EXPR:              tcode = Max_Expr; break;
    case ABS_EXPR:              tcode = Abs_Expr; break;
    case TRUTH_ANDIF_EXPR:      tcode = Truth_Andif_Expr; break;
    case TRUTH_ORIF_EXPR:       tcode = Truth_Orif_Expr; break;
    case TRUTH_AND_EXPR:        tcode = Truth_And_Expr; break;
    case TRUTH_OR_EXPR:         tcode = Truth_Or_Expr; break;
    case TRUTH_XOR_EXPR:        tcode = Truth_Xor_Expr; break;
    case TRUTH_NOT_EXPR:        tcode = Truth_Not_Expr; break;
    case BIT_AND_EXPR:          tcode = Bit_And_Expr; break;
    case LT_EXPR:               tcode = Lt_Expr; break;
    case LE_EXPR:               tcode = Le_Expr; break;
    case GT_EXPR:               tcode = Gt_Expr; break;
    case GE_EXPR:               tcode = Ge_Expr; break;
    case EQ_EXPR:               tcode = Eq_Expr; break;
    case NE_EXPR:               tcode = Ne_Expr; break;

    default:
      return No_Uint;
    }

  /* Now get each of the operands that's relevant for this code.  If any
     cannot be expressed as a repinfo node, say we can't.  */
  for (i = 0; i < 3; i++)
    ops[i] = No_Uint;

  for (i = 0; i < len; i++)
    {
      ops[i] = annotate_value (TREE_OPERAND (gnu_size, i));
      if (ops[i] == No_Uint)
        return No_Uint;
    }

  ret = Create_Node (tcode, ops[0], ops[1], ops[2]);

  /* Save the result in the cache.  */
  if (h)
    {
      *h = GGC_NEW (struct tree_int_map);
      (*h)->base.from = gnu_size;
      (*h)->to = ret;
    }

  return ret;
}

/* Given GNAT_ENTITY, a record type, and GNU_TYPE, its corresponding
   GCC type, set Component_Bit_Offset and Esize to the position and size
   used by Gigi.  */

static void
annotate_rep (Entity_Id gnat_entity, tree gnu_type)
{
  tree gnu_list;
  tree gnu_entry;
  Entity_Id gnat_field;

  /* We operate by first making a list of all fields and their positions
     (we can get the sizes easily at any time) by a recursive call
     and then update all the sizes into the tree.  */
  gnu_list = compute_field_positions (gnu_type, NULL_TREE,
                                      size_zero_node, bitsize_zero_node,
                                      BIGGEST_ALIGNMENT);

  for (gnat_field = First_Entity (gnat_entity); Present (gnat_field);
       gnat_field = Next_Entity (gnat_field))
    if ((Ekind (gnat_field) == E_Component
         || (Ekind (gnat_field) == E_Discriminant
             && !Is_Unchecked_Union (Scope (gnat_field)))))
      {
        tree parent_offset = bitsize_zero_node;

        gnu_entry = purpose_member (gnat_to_gnu_field_decl (gnat_field),
                                    gnu_list);

        if (gnu_entry)
          {
            if (type_annotate_only && Is_Tagged_Type (gnat_entity))
              {
                /* In this mode the tag and parent components have not been
                   generated, so we add the appropriate offset to each
                   component.  For a component appearing in the current
                   extension, the offset is the size of the parent.  */
            if (Is_Derived_Type (gnat_entity)
                && Original_Record_Component (gnat_field) == gnat_field)
              parent_offset
                = UI_To_gnu (Esize (Etype (Base_Type (gnat_entity))),
                             bitsizetype);
            else
              parent_offset = bitsize_int (POINTER_SIZE);
              }

          Set_Component_Bit_Offset
            (gnat_field,
             annotate_value
             (size_binop (PLUS_EXPR,
                          bit_from_pos (TREE_PURPOSE (TREE_VALUE (gnu_entry)),
                                        TREE_VALUE (TREE_VALUE
                                                    (TREE_VALUE (gnu_entry)))),
                          parent_offset)));

            Set_Esize (gnat_field,
                       annotate_value (DECL_SIZE (TREE_PURPOSE (gnu_entry))));
          }
        else if (Is_Tagged_Type (gnat_entity)
                 && Is_Derived_Type (gnat_entity))
          {
            /* If there is no gnu_entry, this is an inherited component whose
               position is the same as in the parent type.  */
            Set_Component_Bit_Offset
              (gnat_field,
               Component_Bit_Offset (Original_Record_Component (gnat_field)));
            Set_Esize (gnat_field,
                       Esize (Original_Record_Component (gnat_field)));
          }
      }
}

/* Scan all fields in GNU_TYPE and build entries where TREE_PURPOSE is the
   FIELD_DECL and TREE_VALUE a TREE_LIST with TREE_PURPOSE being the byte
   position and TREE_VALUE being a TREE_LIST with TREE_PURPOSE the value to be
   placed into DECL_OFFSET_ALIGN and TREE_VALUE the bit position.  GNU_POS is
   to be added to the position, GNU_BITPOS to the bit position, OFFSET_ALIGN is
   the present value of DECL_OFFSET_ALIGN and GNU_LIST is a list of the entries
   so far.  */

static tree
compute_field_positions (tree gnu_type, tree gnu_list, tree gnu_pos,
                         tree gnu_bitpos, unsigned int offset_align)
{
  tree gnu_field;
  tree gnu_result = gnu_list;

  for (gnu_field = TYPE_FIELDS (gnu_type); gnu_field;
       gnu_field = TREE_CHAIN (gnu_field))
    {
      tree gnu_our_bitpos = size_binop (PLUS_EXPR, gnu_bitpos,
                                        DECL_FIELD_BIT_OFFSET (gnu_field));
      tree gnu_our_offset = size_binop (PLUS_EXPR, gnu_pos,
                                        DECL_FIELD_OFFSET (gnu_field));
      unsigned int our_offset_align
        = MIN (offset_align, DECL_OFFSET_ALIGN (gnu_field));

      gnu_result
        = tree_cons (gnu_field,
                     tree_cons (gnu_our_offset,
                                tree_cons (size_int (our_offset_align),
                                           gnu_our_bitpos, NULL_TREE),
                                NULL_TREE),
                     gnu_result);

      if (DECL_INTERNAL_P (gnu_field))
        gnu_result
          = compute_field_positions (TREE_TYPE (gnu_field), gnu_result,
                                     gnu_our_offset, gnu_our_bitpos,
                                     our_offset_align);
    }

  return gnu_result;
}
\f
/* UINT_SIZE is a Uint giving the specified size for an object of GNU_TYPE
   corresponding to GNAT_OBJECT.  If size is valid, return a tree corresponding
   to its value.  Otherwise return 0.  KIND is VAR_DECL is we are specifying
   the size for an object, TYPE_DECL for the size of a type, and FIELD_DECL
   for the size of a field.  COMPONENT_P is true if we are being called
   to process the Component_Size of GNAT_OBJECT.  This is used for error
   message handling and to indicate to use the object size of GNU_TYPE.
   ZERO_OK is true if a size of zero is permitted; if ZERO_OK is false,
   it means that a size of zero should be treated as an unspecified size.  */

static tree
validate_size (Uint uint_size, tree gnu_type, Entity_Id gnat_object,
               enum tree_code kind, bool component_p, bool zero_ok)
{
  Node_Id gnat_error_node;
  tree type_size, size;

  if (kind == VAR_DECL
      /* If a type needs strict alignment, a component of this type in
         a packed record cannot be packed and thus uses the type size.  */
      || (kind == TYPE_DECL && Strict_Alignment (gnat_object)))
    type_size = TYPE_SIZE (gnu_type);
  else
    type_size = rm_size (gnu_type);

  /* Find the node to use for errors.  */
  if ((Ekind (gnat_object) == E_Component
       || Ekind (gnat_object) == E_Discriminant)
      && Present (Component_Clause (gnat_object)))
    gnat_error_node = Last_Bit (Component_Clause (gnat_object));
  else if (Present (Size_Clause (gnat_object)))
    gnat_error_node = Expression (Size_Clause (gnat_object));
  else
    gnat_error_node = gnat_object;

  /* Return 0 if no size was specified, either because Esize was not Present or
     the specified size was zero.  */
  if (No (uint_size) || uint_size == No_Uint)
    return NULL_TREE;

  /* Get the size as a tree.  Give an error if a size was specified, but cannot
     be represented as in sizetype.  */
  size = UI_To_gnu (uint_size, bitsizetype);
  if (TREE_OVERFLOW (size))
    {
      post_error_ne (component_p ? "component size of & is too large"
                     : "size of & is too large",
                     gnat_error_node, gnat_object);
      return NULL_TREE;
    }

  /* Ignore a negative size since that corresponds to our back-annotation.
     Also ignore a zero size unless a size clause exists.  */
  else if (tree_int_cst_sgn (size) < 0 || (integer_zerop (size) && !zero_ok))
    return NULL_TREE;

  /* The size of objects is always a multiple of a byte.  */
  if (kind == VAR_DECL
      && !integer_zerop (size_binop (TRUNC_MOD_EXPR, size, bitsize_unit_node)))
    {
      if (component_p)
        post_error_ne ("component size for& is not a multiple of Storage_Unit",
                       gnat_error_node, gnat_object);
      else
        post_error_ne ("size for& is not a multiple of Storage_Unit",
                       gnat_error_node, gnat_object);
      return NULL_TREE;
    }

  /* If this is an integral type or a packed array type, the front-end has
     verified the size, so we need not do it here (which would entail
     checking against the bounds).  However, if this is an aliased object, it
     may not be smaller than the type of the object.  */
  if ((INTEGRAL_TYPE_P (gnu_type) || TYPE_IS_PACKED_ARRAY_TYPE_P (gnu_type))
      && !(kind == VAR_DECL && Is_Aliased (gnat_object)))
    return size;

  /* If the object is a record that contains a template, add the size of
     the template to the specified size.  */
  if (TREE_CODE (gnu_type) == RECORD_TYPE
      && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
    size = size_binop (PLUS_EXPR, DECL_SIZE (TYPE_FIELDS (gnu_type)), size);

  /* Modify the size of the type to be that of the maximum size if it has a
     discriminant.  */
  if (type_size && CONTAINS_PLACEHOLDER_P (type_size))
    type_size = max_size (type_size, true);

  /* If this is an access type or a fat pointer, the minimum size is that given
     by the smallest integral mode that's valid for pointers.  */
  if ((TREE_CODE (gnu_type) == POINTER_TYPE) || TYPE_FAT_POINTER_P (gnu_type))
    {
      enum machine_mode p_mode;

      for (p_mode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           !targetm.valid_pointer_mode (p_mode);
           p_mode = GET_MODE_WIDER_MODE (p_mode))
        ;

      type_size = bitsize_int (GET_MODE_BITSIZE (p_mode));
    }

  /* If the size of the object is a constant, the new size must not be
     smaller.  */
  if (TREE_CODE (type_size) != INTEGER_CST
      || TREE_OVERFLOW (type_size)
      || tree_int_cst_lt (size, type_size))
    {
      if (component_p)
        post_error_ne_tree
          ("component size for& too small{, minimum allowed is ^}",
           gnat_error_node, gnat_object, type_size);
      else
        post_error_ne_tree ("size for& too small{, minimum allowed is ^}",
                            gnat_error_node, gnat_object, type_size);

      if (kind == VAR_DECL && !component_p
          && TREE_CODE (rm_size (gnu_type)) == INTEGER_CST
          && !tree_int_cst_lt (size, rm_size (gnu_type)))
        post_error_ne_tree_2
          ("\\size of ^ is not a multiple of alignment (^ bits)",
           gnat_error_node, gnat_object, rm_size (gnu_type),
           TYPE_ALIGN (gnu_type));

      else if (INTEGRAL_TYPE_P (gnu_type))
        post_error_ne ("\\size would be legal if & were not aliased!",
                       gnat_error_node, gnat_object);

      return NULL_TREE;
    }

  return size;
}
\f
/* Similarly, but both validate and process a value of RM_Size.  This
   routine is only called for types.  */

static void
set_rm_size (Uint uint_size, tree gnu_type, Entity_Id gnat_entity)
{
  /* Only give an error if a Value_Size clause was explicitly given.
     Otherwise, we'd be duplicating an error on the Size clause.  */
  Node_Id gnat_attr_node
    = Get_Attribute_Definition_Clause (gnat_entity, Attr_Value_Size);
  tree old_size = rm_size (gnu_type);
  tree size;

  /* Get the size as a tree.  Do nothing if none was specified, either
     because RM_Size was not Present or if the specified size was zero.
     Give an error if a size was specified, but cannot be represented as
     in sizetype.  */
  if (No (uint_size) || uint_size == No_Uint)
    return;

  size = UI_To_gnu (uint_size, bitsizetype);
  if (TREE_OVERFLOW (size))
    {
      if (Present (gnat_attr_node))
        post_error_ne ("Value_Size of & is too large", gnat_attr_node,
                       gnat_entity);

      return;
    }

  /* Ignore a negative size since that corresponds to our back-annotation.
     Also ignore a zero size unless a size clause exists, a Value_Size
     clause exists, or this is an integer type, in which case the
     front end will have always set it.  */
  else if (tree_int_cst_sgn (size) < 0
           || (integer_zerop (size) && No (gnat_attr_node)
               && !Has_Size_Clause (gnat_entity)
               && !Is_Discrete_Or_Fixed_Point_Type (gnat_entity)))
    return;

  /* If the old size is self-referential, get the maximum size.  */
  if (CONTAINS_PLACEHOLDER_P (old_size))
    old_size = max_size (old_size, true);

  /* If the size of the object is a constant, the new size must not be
     smaller (the front end checks this for scalar types).  */
  if (TREE_CODE (old_size) != INTEGER_CST
      || TREE_OVERFLOW (old_size)
      || (AGGREGATE_TYPE_P (gnu_type)
          && tree_int_cst_lt (size, old_size)))
    {
      if (Present (gnat_attr_node))
        post_error_ne_tree
          ("Value_Size for& too small{, minimum allowed is ^}",
           gnat_attr_node, gnat_entity, old_size);

      return;
    }

  /* Otherwise, set the RM_Size.  */
  if (TREE_CODE (gnu_type) == INTEGER_TYPE
      && Is_Discrete_Or_Fixed_Point_Type (gnat_entity))
    TYPE_RM_SIZE_NUM (gnu_type) = size;
  else if (TREE_CODE (gnu_type) == ENUMERAL_TYPE
           || TREE_CODE (gnu_type) == BOOLEAN_TYPE)
    TYPE_RM_SIZE_NUM (gnu_type) = size;
  else if ((TREE_CODE (gnu_type) == RECORD_TYPE
            || TREE_CODE (gnu_type) == UNION_TYPE
            || TREE_CODE (gnu_type) == QUAL_UNION_TYPE)
           && !TYPE_IS_FAT_POINTER_P (gnu_type))
    SET_TYPE_ADA_SIZE (gnu_type, size);
}
\f
/* Given a type TYPE, return a new type whose size is appropriate for SIZE.
   If TYPE is the best type, return it.  Otherwise, make a new type.  We
   only support new integral and pointer types.  FOR_BIASED is true if
   we are making a biased type.  */

static tree
make_type_from_size (tree type, tree size_tree, bool for_biased)
{
  unsigned HOST_WIDE_INT size;
  bool biased_p;
  tree new_type;

  /* If size indicates an error, just return TYPE to avoid propagating
     the error.  Likewise if it's too large to represent.  */
  if (!size_tree || !host_integerp (size_tree, 1))
    return type;

  size = tree_low_cst (size_tree, 1);

  switch (TREE_CODE (type))
    {
    case INTEGER_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
      biased_p = (TREE_CODE (type) == INTEGER_TYPE
                  && TYPE_BIASED_REPRESENTATION_P (type));

      /* Only do something if the type is not a packed array type and
         doesn't already have the proper size.  */
      if (TYPE_PACKED_ARRAY_TYPE_P (type)
          || (TYPE_PRECISION (type) == size && biased_p == for_biased))
        break;

      biased_p |= for_biased;
      size = MIN (size, LONG_LONG_TYPE_SIZE);

      if (TYPE_UNSIGNED (type) || biased_p)
        new_type = make_unsigned_type (size);
      else
        new_type = make_signed_type (size);
      TREE_TYPE (new_type) = TREE_TYPE (type) ? TREE_TYPE (type) : type;
      TYPE_MIN_VALUE (new_type)
        = convert (TREE_TYPE (new_type), TYPE_MIN_VALUE (type));
      TYPE_MAX_VALUE (new_type)
        = convert (TREE_TYPE (new_type), TYPE_MAX_VALUE (type));
      /* Propagate the name to avoid creating a fake subrange type.  */
      if (TYPE_NAME (type))
        {
          if (TREE_CODE (TYPE_NAME (type)) == TYPE_DECL)
            TYPE_NAME (new_type) = DECL_NAME (TYPE_NAME (type));
          else
            TYPE_NAME (new_type) = TYPE_NAME (type);
        }
      TYPE_BIASED_REPRESENTATION_P (new_type) = biased_p;
      TYPE_RM_SIZE_NUM (new_type) = bitsize_int (size);
      return new_type;

    case RECORD_TYPE:
      /* Do something if this is a fat pointer, in which case we
         may need to return the thin pointer.  */
      if (TYPE_IS_FAT_POINTER_P (type) && size < POINTER_SIZE * 2)
        {
          enum machine_mode p_mode = mode_for_size (size, MODE_INT, 0);
          if (!targetm.valid_pointer_mode (p_mode))
            p_mode = ptr_mode;
          return
            build_pointer_type_for_mode
              (TYPE_OBJECT_RECORD_TYPE (TYPE_UNCONSTRAINED_ARRAY (type)),
               p_mode, 0);
        }
      break;

    case POINTER_TYPE:
      /* Only do something if this is a thin pointer, in which case we
         may need to return the fat pointer.  */
      if (TYPE_THIN_POINTER_P (type) && size >= POINTER_SIZE * 2)
        return
          build_pointer_type (TYPE_UNCONSTRAINED_ARRAY (TREE_TYPE (type)));
      break;

    default:
      break;
    }

  return type;
}
\f
/* ALIGNMENT is a Uint giving the alignment specified for GNAT_ENTITY,
   a type or object whose present alignment is ALIGN.  If this alignment is
   valid, return it.  Otherwise, give an error and return ALIGN.  */

static unsigned int
validate_alignment (Uint alignment, Entity_Id gnat_entity, unsigned int align)
{
  unsigned int max_allowed_alignment = get_target_maximum_allowed_alignment ();
  unsigned int new_align;
  Node_Id gnat_error_node;

  /* Don't worry about checking alignment if alignment was not specified
     by the source program and we already posted an error for this entity.  */
  if (Error_Posted (gnat_entity) && !Has_Alignment_Clause (gnat_entity))
    return align;

  /* Post the error on the alignment clause if any.  */
  if (Present (Alignment_Clause (gnat_entity)))
    gnat_error_node = Expression (Alignment_Clause (gnat_entity));
  else
    gnat_error_node = gnat_entity;

  /* Within GCC, an alignment is an integer, so we must make sure a value is
     specified that fits in that range.  Also, there is an upper bound to
     alignments we can support/allow.  */
  if (!UI_Is_In_Int_Range (alignment)
      || ((new_align = UI_To_Int (alignment)) > max_allowed_alignment))
    post_error_ne_num ("largest supported alignment for& is ^",
                       gnat_error_node, gnat_entity, max_allowed_alignment);
  else if (!(Present (Alignment_Clause (gnat_entity))
             && From_At_Mod (Alignment_Clause (gnat_entity)))
           && new_align * BITS_PER_UNIT < align)
    post_error_ne_num ("alignment for& must be at least ^",
                       gnat_error_node, gnat_entity,
                       align / BITS_PER_UNIT);
  else
    {
      new_align = (new_align > 0 ? new_align * BITS_PER_UNIT : 1);
      if (new_align > align)
        align = new_align;
    }

  return align;
}

/* Return the smallest alignment not less than SIZE.  */

static unsigned int
ceil_alignment (unsigned HOST_WIDE_INT size)
{
  return (unsigned int) 1 << (floor_log2 (size - 1) + 1);
}
\f
/* Verify that OBJECT, a type or decl, is something we can implement
   atomically.  If not, give an error for GNAT_ENTITY.  COMP_P is true
   if we require atomic components.  */

static void
check_ok_for_atomic (tree object, Entity_Id gnat_entity, bool comp_p)
{
  Node_Id gnat_error_point = gnat_entity;
  Node_Id gnat_node;
  enum machine_mode mode;
  unsigned int align;
  tree size;

  /* There are three case of what OBJECT can be.  It can be a type, in which
     case we take the size, alignment and mode from the type.  It can be a
     declaration that was indirect, in which case the relevant values are
     that of the type being pointed to, or it can be a normal declaration,
     in which case the values are of the decl.  The code below assumes that
     OBJECT is either a type or a decl.  */
  if (TYPE_P (object))
    {
      mode = TYPE_MODE (object);
      align = TYPE_ALIGN (object);
      size = TYPE_SIZE (object);
    }
  else if (DECL_BY_REF_P (object))
    {
      mode = TYPE_MODE (TREE_TYPE (TREE_TYPE (object)));
      align = TYPE_ALIGN (TREE_TYPE (TREE_TYPE (object)));
      size = TYPE_SIZE (TREE_TYPE (TREE_TYPE (object)));
    }
  else
    {
      mode = DECL_MODE (object);
      align = DECL_ALIGN (object);
      size = DECL_SIZE (object);
    }

  /* Consider all floating-point types atomic and any types that that are
     represented by integers no wider than a machine word.  */
  if (GET_MODE_CLASS (mode) == MODE_FLOAT
      || ((GET_MODE_CLASS (mode) == MODE_INT
           || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
          && GET_MODE_BITSIZE (mode) <= BITS_PER_WORD))
    return;

  /* For the moment, also allow anything that has an alignment equal
     to its size and which is smaller than a word.  */
  if (size && TREE_CODE (size) == INTEGER_CST
      && compare_tree_int (size, align) == 0
      && align <= BITS_PER_WORD)
    return;

  for (gnat_node = First_Rep_Item (gnat_entity); Present (gnat_node);
       gnat_node = Next_Rep_Item (gnat_node))
    {
      if (!comp_p && Nkind (gnat_node) == N_Pragma
          && (Get_Pragma_Id (Chars (Pragma_Identifier (gnat_node)))
              == Pragma_Atomic))
        gnat_error_point = First (Pragma_Argument_Associations (gnat_node));
      else if (comp_p && Nkind (gnat_node) == N_Pragma
               && (Get_Pragma_Id (Chars (Pragma_Identifier (gnat_node)))
                   == Pragma_Atomic_Components))
        gnat_error_point = First (Pragma_Argument_Associations (gnat_node));
    }

  if (comp_p)
    post_error_ne ("atomic access to component of & cannot be guaranteed",
                   gnat_error_point, gnat_entity);
  else
    post_error_ne ("atomic access to & cannot be guaranteed",
                   gnat_error_point, gnat_entity);
}
\f
/* Check if FTYPE1 and FTYPE2, two potentially different function type nodes,
   have compatible signatures so that a call using one type may be safely
   issued if the actual target function type is the other.  Return 1 if it is
   the case, 0 otherwise, and post errors on the incompatibilities.

   This is used when an Ada subprogram is mapped onto a GCC builtin, to ensure
   that calls to the subprogram will have arguments suitable for the later
   underlying builtin expansion.  */

static int
compatible_signatures_p (tree ftype1, tree ftype2)
{
  /* As of now, we only perform very trivial tests and consider it's the
     programmer's responsibility to ensure the type correctness in the Ada
     declaration, as in the regular Import cases.

     Mismatches typically result in either error messages from the builtin
     expander, internal compiler errors, or in a real call sequence.  This
     should be refined to issue diagnostics helping error detection and
     correction.  */

  /* Almost fake test, ensuring a use of each argument.  */
  if (ftype1 == ftype2)
    return 1;

  return 1;
}
\f
/* Given a type T, a FIELD_DECL F, and a replacement value R, return a new
   type with all size expressions that contain F updated by replacing F
   with R.  If F is NULL_TREE, always make a new RECORD_TYPE, even if
   nothing has changed.  */

tree
substitute_in_type (tree t, tree f, tree r)
{
  tree new = t;
  tree tem;

  switch (TREE_CODE (t))
    {
    case INTEGER_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
      if (CONTAINS_PLACEHOLDER_P (TYPE_MIN_VALUE (t))
          || CONTAINS_PLACEHOLDER_P (TYPE_MAX_VALUE (t)))
        {
          tree low = SUBSTITUTE_IN_EXPR (TYPE_MIN_VALUE (t), f, r);
          tree high = SUBSTITUTE_IN_EXPR (TYPE_MAX_VALUE (t), f, r);

          if (low == TYPE_MIN_VALUE (t) && high == TYPE_MAX_VALUE (t))
            return t;

          new = build_range_type (TREE_TYPE (t), low, high);
          if (TYPE_INDEX_TYPE (t))
            SET_TYPE_INDEX_TYPE
              (new, substitute_in_type (TYPE_INDEX_TYPE (t), f, r));
          return new;
        }

      return t;

    case REAL_TYPE:
      if (CONTAINS_PLACEHOLDER_P (TYPE_MIN_VALUE (t))
          || CONTAINS_PLACEHOLDER_P (TYPE_MAX_VALUE (t)))
        {
          tree low = NULL_TREE, high = NULL_TREE;

          if (TYPE_MIN_VALUE (t))
            low = SUBSTITUTE_IN_EXPR (TYPE_MIN_VALUE (t), f, r);
          if (TYPE_MAX_VALUE (t))
            high = SUBSTITUTE_IN_EXPR (TYPE_MAX_VALUE (t), f, r);

          if (low == TYPE_MIN_VALUE (t) && high == TYPE_MAX_VALUE (t))
            return t;

          t = copy_type (t);
          TYPE_MIN_VALUE (t) = low;
          TYPE_MAX_VALUE (t) = high;
        }
      return t;

    case COMPLEX_TYPE:
      tem = substitute_in_type (TREE_TYPE (t), f, r);
      if (tem == TREE_TYPE (t))
        return t;

      return build_complex_type (tem);

    case OFFSET_TYPE:
    case METHOD_TYPE:
    case FUNCTION_TYPE:
    case LANG_TYPE:
      /* Don't know how to do these yet.  */
      gcc_unreachable ();

    case ARRAY_TYPE:
      {
        tree component = substitute_in_type (TREE_TYPE (t), f, r);
        tree domain = substitute_in_type (TYPE_DOMAIN (t), f, r);

        if (component == TREE_TYPE (t) && domain == TYPE_DOMAIN (t))
          return t;

        new = build_array_type (component, domain);
        TYPE_SIZE (new) = 0;
        TYPE_NONALIASED_COMPONENT (new) = TYPE_NONALIASED_COMPONENT (t);
        TYPE_MULTI_ARRAY_P (new) = TYPE_MULTI_ARRAY_P (t);
        TYPE_CONVENTION_FORTRAN_P (new) = TYPE_CONVENTION_FORTRAN_P (t);
        layout_type (new);
        TYPE_ALIGN (new) = TYPE_ALIGN (t);
        TYPE_USER_ALIGN (new) = TYPE_USER_ALIGN (t);

        /* If we had bounded the sizes of T by a constant, bound the sizes of
           NEW by the same constant.  */
        if (TREE_CODE (TYPE_SIZE (t)) == MIN_EXPR)
          TYPE_SIZE (new)
            = size_binop (MIN_EXPR, TREE_OPERAND (TYPE_SIZE (t), 1),
                          TYPE_SIZE (new));
        if (TREE_CODE (TYPE_SIZE_UNIT (t)) == MIN_EXPR)
          TYPE_SIZE_UNIT (new)
            = size_binop (MIN_EXPR, TREE_OPERAND (TYPE_SIZE_UNIT (t), 1),
                          TYPE_SIZE_UNIT (new));
        return new;
      }

    case RECORD_TYPE:
    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      {
        tree field;
        bool changed_field
          = (f == NULL_TREE && !TREE_CONSTANT (TYPE_SIZE (t)));
        bool field_has_rep = false;
        tree last_field = NULL_TREE;

        tree new = copy_type (t);

        /* Start out with no fields, make new fields, and chain them
           in.  If we haven't actually changed the type of any field,
           discard everything we've done and return the old type.  */

        TYPE_FIELDS (new) = NULL_TREE;
        TYPE_SIZE (new) = NULL_TREE;

        for (field = TYPE_FIELDS (t); field; field = TREE_CHAIN (field))
          {
            tree new_field = copy_node (field);

            TREE_TYPE (new_field)
              = substitute_in_type (TREE_TYPE (new_field), f, r);

            if (DECL_HAS_REP_P (field) && !DECL_INTERNAL_P (field))
              field_has_rep = true;
            else if (TREE_TYPE (new_field) != TREE_TYPE (field))
              changed_field = true;

            /* If this is an internal field and the type of this field is
               a UNION_TYPE or RECORD_TYPE with no elements, ignore it.  If
               the type just has one element, treat that as the field.
               But don't do this if we are processing a QUAL_UNION_TYPE.  */
            if (TREE_CODE (t) != QUAL_UNION_TYPE
                && DECL_INTERNAL_P (new_field)
                && (TREE_CODE (TREE_TYPE (new_field)) == UNION_TYPE
                    || TREE_CODE (TREE_TYPE (new_field)) == RECORD_TYPE))
              {
                if (!TYPE_FIELDS (TREE_TYPE (new_field)))
                  continue;

                if (!TREE_CHAIN (TYPE_FIELDS (TREE_TYPE (new_field))))
                  {
                    tree next_new_field
                      = copy_node (TYPE_FIELDS (TREE_TYPE (new_field)));

                    /* Make sure omitting the union doesn't change
                       the layout.  */
                    DECL_ALIGN (next_new_field) = DECL_ALIGN (new_field);
                    new_field = next_new_field;
                  }
              }

            DECL_CONTEXT (new_field) = new;
            SET_DECL_ORIGINAL_FIELD (new_field,
                                     (DECL_ORIGINAL_FIELD (field)
                                      ? DECL_ORIGINAL_FIELD (field) : field));

            /* If the size of the old field was set at a constant,
               propagate the size in case the type's size was variable.
               (This occurs in the case of a variant or discriminated
               record with a default size used as a field of another
               record.)  */
            DECL_SIZE (new_field)
              = TREE_CODE (DECL_SIZE (field)) == INTEGER_CST
                ? DECL_SIZE (field) : NULL_TREE;
            DECL_SIZE_UNIT (new_field)
              = TREE_CODE (DECL_SIZE_UNIT (field)) == INTEGER_CST
                ? DECL_SIZE_UNIT (field) : NULL_TREE;

            if (TREE_CODE (t) == QUAL_UNION_TYPE)
              {
                tree new_q = SUBSTITUTE_IN_EXPR (DECL_QUALIFIER (field), f, r);

                if (new_q != DECL_QUALIFIER (new_field))
                  changed_field = true;

                /* Do the substitution inside the qualifier and if we find
                   that this field will not be present, omit it.  */
                DECL_QUALIFIER (new_field) = new_q;

                if (integer_zerop (DECL_QUALIFIER (new_field)))
                  continue;
              }

            if (!last_field)
              TYPE_FIELDS (new) = new_field;
            else
              TREE_CHAIN (last_field) = new_field;

            last_field = new_field;

            /* If this is a qualified type and this field will always be
               present, we are done.  */
            if (TREE_CODE (t) == QUAL_UNION_TYPE
                && integer_onep (DECL_QUALIFIER (new_field)))
              break;
          }

        /* If this used to be a qualified union type, but we now know what
           field will be present, make this a normal union.  */
        if (changed_field && TREE_CODE (new) == QUAL_UNION_TYPE
            && (!TYPE_FIELDS (new)
                || integer_onep (DECL_QUALIFIER (TYPE_FIELDS (new)))))
          TREE_SET_CODE (new, UNION_TYPE);
        else if (!changed_field)
          return t;

        gcc_assert (!field_has_rep);
        layout_type (new);

        /* If the size was originally a constant use it.  */
        if (TYPE_SIZE (t) && TREE_CODE (TYPE_SIZE (t)) == INTEGER_CST
            && TREE_CODE (TYPE_SIZE (new)) != INTEGER_CST)
          {
            TYPE_SIZE (new) = TYPE_SIZE (t);
            TYPE_SIZE_UNIT (new) = TYPE_SIZE_UNIT (t);
            SET_TYPE_ADA_SIZE (new, TYPE_ADA_SIZE (t));
          }

        return new;
      }

    default:
      return t;
    }
}
\f
/* Return the "RM size" of GNU_TYPE.  This is the actual number of bits
   needed to represent the object.  */

tree
rm_size (tree gnu_type)
{
  /* For integer types, this is the precision.  For record types, we store
     the size explicitly.  For other types, this is just the size.  */

  if (INTEGRAL_TYPE_P (gnu_type) && TYPE_RM_SIZE (gnu_type))
    return TYPE_RM_SIZE (gnu_type);
  else if (TREE_CODE (gnu_type) == RECORD_TYPE
           && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
    /* Return the rm_size of the actual data plus the size of the template.  */
    return
      size_binop (PLUS_EXPR,
                  rm_size (TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_type)))),
                  DECL_SIZE (TYPE_FIELDS (gnu_type)));
  else if ((TREE_CODE (gnu_type) == RECORD_TYPE
            || TREE_CODE (gnu_type) == UNION_TYPE
            || TREE_CODE (gnu_type) == QUAL_UNION_TYPE)
           && !TYPE_IS_FAT_POINTER_P (gnu_type)
           && TYPE_ADA_SIZE (gnu_type))
    return TYPE_ADA_SIZE (gnu_type);
  else
    return TYPE_SIZE (gnu_type);
}
\f
/* Return an identifier representing the external name to be used for
   GNAT_ENTITY.  If SUFFIX is specified, the name is followed by "___"
   and the specified suffix.  */

tree
create_concat_name (Entity_Id gnat_entity, const char *suffix)
{
  Entity_Kind kind = Ekind (gnat_entity);

  const char *str = (!suffix ? "" : suffix);
  String_Template temp = {1, strlen (str)};
  Fat_Pointer fp = {str, &temp};

  Get_External_Name_With_Suffix (gnat_entity, fp);

  /* A variable using the Stdcall convention (meaning we are running
     on a Windows box) live in a DLL.  Here we adjust its name to use
     the jump-table, the _imp__NAME contains the address for the NAME
     variable.  */
  if ((kind == E_Variable || kind == E_Constant)
      && Has_Stdcall_Convention (gnat_entity))
    {
      const char *prefix = "_imp__";
      int k, plen = strlen (prefix);

      for (k = 0; k <= Name_Len; k++)
        Name_Buffer [Name_Len - k + plen] = Name_Buffer [Name_Len - k];
      strncpy (Name_Buffer, prefix, plen);
    }

  return get_identifier (Name_Buffer);
}

/* Return the name to be used for GNAT_ENTITY.  If a type, create a
   fully-qualified name, possibly with type information encoding.
   Otherwise, return the name.  */

tree
get_entity_name (Entity_Id gnat_entity)
{
  Get_Encoded_Name (gnat_entity);
  return get_identifier (Name_Buffer);
}

/* Given GNU_ID, an IDENTIFIER_NODE containing a name and SUFFIX, a
   string, return a new IDENTIFIER_NODE that is the concatenation of
   the name in GNU_ID and SUFFIX.  */

tree
concat_id_with_name (tree gnu_id, const char *suffix)
{
  int len = IDENTIFIER_LENGTH (gnu_id);

  strncpy (Name_Buffer, IDENTIFIER_POINTER (gnu_id), len);
  strncpy (Name_Buffer + len, "___", 3);
  len += 3;
  strcpy (Name_Buffer + len, suffix);
  return get_identifier (Name_Buffer);
}

#include "gt-ada-decl.h"