gigi.h (renaming_from_generic_instantiation_p): Turn to

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

/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                                 D E C L                                  *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *          Copyright (C) 1992-2017, 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 "target.h"
#include "tree.h"
#include "stringpool.h"
#include "diagnostic-core.h"
#include "alias.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "tree-inline.h"
#include "demangle.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 "uintp.h"
#include "urealp.h"
#include "fe.h"
#include "sinfo.h"
#include "einfo.h"
#include "ada-tree.h"
#include "gigi.h"

/* "stdcall" and "thiscall" conventions should be processed in a specific way
   on 32-bit x86/Windows only.  The macros below are helpers to avoid having
   to check for a Windows specific attribute throughout this unit.  */

#if TARGET_DLLIMPORT_DECL_ATTRIBUTES
#ifdef TARGET_64BIT
#define Has_Stdcall_Convention(E) \
  (!TARGET_64BIT && Convention (E) == Convention_Stdcall)
#define Has_Thiscall_Convention(E) \
  (!TARGET_64BIT && is_cplusplus_method (E))
#else
#define Has_Stdcall_Convention(E) (Convention (E) == Convention_Stdcall)
#define Has_Thiscall_Convention(E) (is_cplusplus_method (E))
#endif
#else
#define Has_Stdcall_Convention(E) 0
#define Has_Thiscall_Convention(E) 0
#endif

#define STDCALL_PREFIX "_imp__"

/* Stack realignment is necessary for functions with foreign conventions when
   the ABI doesn't mandate as much as what the compiler assumes - that is, up
   to PREFERRED_STACK_BOUNDARY.

   Such realignment can be requested with a dedicated function type attribute
   on the targets that support it.  We define FOREIGN_FORCE_REALIGN_STACK to
   characterize the situations where the attribute should be set.  We rely on
   compiler configuration settings for 'main' to decide.  */

#ifdef MAIN_STACK_BOUNDARY
#define FOREIGN_FORCE_REALIGN_STACK \
  (MAIN_STACK_BOUNDARY < PREFERRED_STACK_BOUNDARY)
#else
#define FOREIGN_FORCE_REALIGN_STACK 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 a record, an array or a subprogram type.  */
static int defer_incomplete_level = 0;
static struct incomplete *defer_incomplete_list;

/* This variable is used to delay expanding types coming from a limited with
   clause and completed Taft Amendment types until the end of the spec.  */
static struct incomplete *defer_limited_with_list;

typedef struct subst_pair_d {
  tree discriminant;
  tree replacement;
} subst_pair;


typedef struct variant_desc_d {
  /* The type of the variant.  */
  tree type;

  /* The associated field.  */
  tree field;

  /* The value of the qualifier.  */
  tree qual;

  /* The type of the variant after transformation.  */
  tree new_type;
} variant_desc;


/* A map used to cache the result of annotate_value.  */
struct value_annotation_hasher : ggc_cache_ptr_hash<tree_int_map>
{
  static inline hashval_t
  hash (tree_int_map *m)
  {
    return htab_hash_pointer (m->base.from);
  }

  static inline bool
  equal (tree_int_map *a, tree_int_map *b)
  {
    return a->base.from == b->base.from;
  }

  static int
  keep_cache_entry (tree_int_map *&m)
  {
    return ggc_marked_p (m->base.from);
  }
};

static GTY ((cache)) hash_table<value_annotation_hasher> *annotate_value_cache;

/* A map used to associate a dummy type with a list of subprogram entities.  */
struct GTY((for_user)) tree_entity_vec_map
{
  struct tree_map_base base;
  vec<Entity_Id, va_gc_atomic> *to;
};

void
gt_pch_nx (Entity_Id &)
{
}

void
gt_pch_nx (Entity_Id *x, gt_pointer_operator op, void *cookie)
{
  op (x, cookie);
}

struct dummy_type_hasher : ggc_cache_ptr_hash<tree_entity_vec_map>
{
  static inline hashval_t
  hash (tree_entity_vec_map *m)
  {
    return htab_hash_pointer (m->base.from);
  }

  static inline bool
  equal (tree_entity_vec_map *a, tree_entity_vec_map *b)
  {
    return a->base.from == b->base.from;
  }

  static int
  keep_cache_entry (tree_entity_vec_map *&m)
  {
    return ggc_marked_p (m->base.from);
  }
};

static GTY ((cache)) hash_table<dummy_type_hasher> *dummy_to_subprog_map;

static void prepend_one_attribute (struct attrib **,
                                   enum attrib_type, tree, tree, Node_Id);
static void prepend_one_attribute_pragma (struct attrib **, Node_Id);
static void prepend_attributes (struct attrib **, Entity_Id);
static tree elaborate_expression (Node_Id, Entity_Id, const char *, bool, bool,
                                  bool);
static bool type_has_variable_size (tree);
static tree elaborate_expression_1 (tree, Entity_Id, const char *, bool, bool);
static tree elaborate_expression_2 (tree, Entity_Id, const char *, bool, bool,
                                    unsigned int);
static tree elaborate_reference (tree, Entity_Id, bool, tree *);
static tree gnat_to_gnu_component_type (Entity_Id, bool, bool);
static tree gnat_to_gnu_subprog_type (Entity_Id, bool, bool, tree *);
static int adjust_packed (tree, tree, int);
static tree gnat_to_gnu_field (Entity_Id, tree, int, bool, bool);
static tree gnu_ext_name_for_subprog (Entity_Id, tree);
static tree change_qualified_type (tree, int);
static void set_nonaliased_component_on_array_type (tree);
static void set_reverse_storage_order_on_array_type (tree);
static bool same_discriminant_p (Entity_Id, Entity_Id);
static bool array_type_has_nonaliased_component (tree, Entity_Id);
static bool compile_time_known_address_p (Node_Id);
static bool cannot_be_superflat (Node_Id);
static bool constructor_address_p (tree);
static bool allocatable_size_p (tree, bool);
static bool initial_value_needs_conversion (tree, tree);
static int compare_field_bitpos (const PTR, const PTR);
static bool components_to_record (Node_Id, Entity_Id, tree, tree, int, bool,
                                  bool, bool, bool, bool, bool, bool, tree,
                                  tree *);
static Uint annotate_value (tree);
static void annotate_rep (Entity_Id, tree);
static tree build_position_list (tree, bool, tree, tree, unsigned int, tree);
static vec<subst_pair> build_subst_list (Entity_Id, Entity_Id, bool);
static vec<variant_desc> build_variant_list (tree, vec<subst_pair>,
                                             vec<variant_desc>);
static tree validate_size (Uint, tree, Entity_Id, enum tree_code, bool, bool);
static void set_rm_size (Uint, tree, Entity_Id);
static unsigned int validate_alignment (Uint, Entity_Id, unsigned int);
static void check_ok_for_atomic_type (tree, Entity_Id, bool);
static tree create_field_decl_from (tree, tree, tree, tree, tree,
                                    vec<subst_pair>);
static tree create_rep_part (tree, tree, tree);
static tree get_rep_part (tree);
static tree create_variant_part_from (tree, vec<variant_desc>, tree,
                                      tree, vec<subst_pair>, bool);
static void copy_and_substitute_in_size (tree, tree, vec<subst_pair>);
static void copy_and_substitute_in_layout (Entity_Id, Entity_Id, tree, tree,
                                           vec<subst_pair>, bool);
static void associate_original_type_to_packed_array (tree, Entity_Id);
static const char *get_entity_char (Entity_Id);

/* The relevant constituents of a subprogram binding to a GCC builtin.  Used
   to pass around calls performing profile compatibility checks.  */

typedef struct {
  Entity_Id gnat_entity;  /* The Ada subprogram entity.  */
  tree ada_fntype;        /* The corresponding GCC type node.  */
  tree btin_fntype;       /* The GCC builtin function type node.  */
} intrin_binding_t;

static bool intrin_profiles_compatible_p (intrin_binding_t *);
\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 true 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.  */

tree
gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition)
{
  /* Contains the kind of the input GNAT node.  */
  const Entity_Kind kind = Ekind (gnat_entity);
  /* True if this is a type.  */
  const bool is_type = IN (kind, Type_Kind);
  /* True if this is an artificial entity.  */
  const bool artificial_p = !Comes_From_Source (gnat_entity);
  /* True if debug info is requested for this entity.  */
  const bool debug_info_p = Needs_Debug_Info (gnat_entity);
  /* True if this entity is to be considered as imported.  */
  const bool imported_p
    = (Is_Imported (gnat_entity) && No (Address_Clause (gnat_entity)));
  /* For a type, contains the equivalent GNAT node to be used in gigi.  */
  Entity_Id gnat_equiv_type = Empty;
  /* Temporary used to walk the GNAT tree.  */
  Entity_Id gnat_temp;
  /* 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_name;
  /* 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;
  /* Size and alignment of the GCC node, if meaningful.  */
  unsigned int esize = 0, align = 0;
  /* Contains the list of attributes directly attached to the entity.  */
  struct attrib *attr_list = NULL;

  /* Since a use of an Itype is a definition, process it as such if it is in
     the main unit, except for E_Access_Subtype because it's actually a use
     of its base type, see below.  */
  if (!definition
      && is_type
      && Is_Itype (gnat_entity)
      && Ekind (gnat_entity) != E_Access_Subtype
      && !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 (Is_Subprogram (gnat_temp)
              && 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
              || (Is_Subprogram (gnat_temp)
                  && present_gnu_tree (gnat_temp)
                  && (current_function_decl
                      == gnat_to_gnu_entity (gnat_temp, NULL_TREE, false))))
            {
              process_type (gnat_entity);
              return get_gnu_tree (gnat_entity);
            }
        }

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

  /* 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 but be careful so as not to trigger its
     premature elaboration.  */
  if ((!definition || (is_type && imported_p))
      && present_gnu_tree (gnat_entity))
    {
      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))
          && (present_gnu_tree (Full_View (gnat_entity))
              || No (Freeze_Node (Full_View (gnat_entity)))))
        {
          gnu_decl
            = gnat_to_gnu_entity (Full_View (gnat_entity), NULL_TREE, false);
          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.  Exceptions
     are for access-to-protected-subprogram types and all access subtypes, as
     another GNAT type is used to lay out the GCC type for them.  */
  gcc_assert (!is_type
              || Known_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
                      || type_annotate_only)));

  /* The 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)));

  /* If we get here, it means we have not yet done anything with this entity.
     If we are not defining it, it must be a type or an entity that is defined
     elsewhere or externally, otherwise we should have defined it already.  */
  gcc_assert (definition
              || type_annotate_only
              || is_type
              || kind == E_Discriminant
              || kind == E_Component
              || kind == E_Label
              || (kind == E_Constant && Present (Full_View (gnat_entity)))
              || Is_Public (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.  Make sure we do not
     inherit another source location.  */
  gnu_entity_name = get_entity_name (gnat_entity);
  if (Sloc (gnat_entity) != No_Location
      && !renaming_from_instantiation_p (gnat_entity))
    Sloc_to_locus (Sloc (gnat_entity), &input_location);

  /* 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.  */
  if (!definition
      && kind != E_Component
      && kind != E_Discriminant
      && Is_Public (gnat_entity)
      && !Is_Statically_Allocated (gnat_entity))
    force_global++, this_global = true;

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

  /* Do some common processing for types.  */
  if (is_type)
    {
      /* Compute the equivalent type to be used in gigi.  */
      gnat_equiv_type = Gigi_Equivalent_Type (gnat_entity);

      /* 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 (Base_Type (gnat_entity) != gnat_entity
          && !Is_First_Subtype (gnat_entity)
          && Has_Gigi_Rep_Item (First_Subtype (Base_Type (gnat_entity))))
        prepend_attributes (&attr_list,
                            First_Subtype (Base_Type (gnat_entity)));

      /* Compute a default value for the size of an elementary type.  */
      if (Known_Esize (gnat_entity) && Is_Elementary_Type (gnat_entity))
        {
          unsigned int max_esize;

          gcc_assert (UI_Is_In_Int_Range (Esize (gnat_entity)));
          esize = UI_To_Int (Esize (gnat_entity));

          if (IN (kind, Float_Kind))
            max_esize = fp_prec_to_size (LONG_DOUBLE_TYPE_SIZE);
          else if (IN (kind, Access_Kind))
            max_esize = POINTER_SIZE * 2;
          else
            max_esize = LONG_LONG_TYPE_SIZE;

          if (esize > max_esize)
           esize = max_esize;
        }
    }

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

        /* If the entity is a discriminant of an extended tagged type used to
           rename a discriminant of the parent type, return the latter.  */
        if (kind == E_Discriminant
            && Present (Corresponding_Discriminant (gnat_entity))
            && Is_Tagged_Type (gnat_record))
          {
            gnu_decl
              = gnat_to_gnu_entity (Corresponding_Discriminant (gnat_entity),
                                    gnu_expr, definition);
            saved = true;
            break;
          }

        /* If the entity is an inherited component (in the case of extended
           tagged record types), just return the original entity, which must
           be a FIELD_DECL.  Likewise for discriminants.  If the entity is a
           non-girder discriminant (in the case of derived untagged record
           types), return the stored discriminant it renames.  */
        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);
            /* GNU_DECL contains a PLACEHOLDER_EXPR for discriminants.  */
            if (kind == E_Discriminant)
              saved = true;
            break;
          }

        /* 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.  */
        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 (Underlying_Type (Scop))
                && Present (Original_Record_Component (gnat_entity)))
              {
                gnu_decl
                  = gnat_to_gnu_entity (Original_Record_Component
                                        (gnat_entity),
                                        gnu_expr, false);
              }
            else
              {
                gnat_to_gnu_entity (Scope (gnat_entity), NULL_TREE, false);
                gnu_decl = get_gnu_tree (gnat_entity);
              }

            saved = true;
            break;
          }

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

      /* 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;
        }

      /* 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, false);
          saved = true;
          break;
        }

      /* If we have a constant that we are not defining, get the expression it
         was defined to represent.  This is necessary to avoid generating dumb
         elaboration code in simple cases, but we may throw it away later if it
         is not a constant.  But do not retrieve it if it is an allocator since
         the designated type might still be dummy at this point.  */
      if (!definition
          && !No_Initialization (Declaration_Node (gnat_entity))
          && Present (Expression (Declaration_Node (gnat_entity)))
          && Nkind (Expression (Declaration_Node (gnat_entity)))
             != N_Allocator)
          /* The expression may contain N_Expression_With_Actions nodes and
             thus object declarations from other units.  Discard them.  */
        gnu_expr
          = gnat_to_gnu_external (Expression (Declaration_Node (gnat_entity)));

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

    case E_Exception:
    case E_Loop_Parameter:
    case E_Out_Parameter:
    case E_Variable:
      {
        const Entity_Id gnat_type = Etype (gnat_entity);
        /* Always create a variable for volatile objects and variables seen
           constant but with a Linker_Section pragma.  */
        bool const_flag
          = ((kind == E_Constant || kind == E_Variable)
             && Is_True_Constant (gnat_entity)
             && !(kind == E_Variable
                  && Present (Linker_Section_Pragma (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))
                 || imported_p));
        bool inner_const_flag = const_flag;
        bool static_flag = Is_Statically_Allocated (gnat_entity);
        /* We implement RM 13.3(19) for exported and imported (non-constant)
           objects by making them volatile.  */
        bool volatile_flag
          = (Treat_As_Volatile (gnat_entity)
             || (!const_flag && (Is_Exported (gnat_entity) || imported_p)));
        bool mutable_p = false;
        bool used_by_ref = false;
        tree gnu_ext_name = NULL_TREE;
        tree renamed_obj = NULL_TREE;
        tree gnu_object_size;

        /* We need to translate the renamed object even though we are only
           referencing the renaming.  But it may contain a call for which
           we'll generate a temporary to hold the return value and which
           is part of the definition of the renaming, so discard it.  */
        if (Present (Renamed_Object (gnat_entity)) && !definition)
          {
            if (kind == E_Exception)
              gnu_expr = gnat_to_gnu_entity (Renamed_Entity (gnat_entity),
                                             NULL_TREE, false);
            else
              gnu_expr = gnat_to_gnu_external (Renamed_Object (gnat_entity));
          }

        /* Get the type after elaborating the renamed object.  */
        if (Has_Foreign_Convention (gnat_entity)
            && Is_Descendant_Of_Address (gnat_type))
          gnu_type = ptr_type_node;
        else
          {
            gnu_type = gnat_to_gnu_type (gnat_type);

            /* If this is a standard exception definition, use the standard
               exception type.  This is necessary to make sure that imported
               and exported views of exceptions are merged in LTO mode.  */
            if (TREE_CODE (TYPE_NAME (gnu_type)) == TYPE_DECL
                && DECL_NAME (TYPE_NAME (gnu_type)) == exception_data_name_id)
              gnu_type = except_type_node;
          }

        /* For a debug renaming declaration, build a debug-only entity.  */
        if (Present (Debug_Renaming_Link (gnat_entity)))
          {
            /* Force a non-null value to make sure the symbol is retained.  */
            tree value = build1 (INDIRECT_REF, gnu_type,
                                 build1 (NOP_EXPR,
                                         build_pointer_type (gnu_type),
                                         integer_minus_one_node));
            gnu_decl = build_decl (input_location,
                                   VAR_DECL, gnu_entity_name, gnu_type);
            SET_DECL_VALUE_EXPR (gnu_decl, value);
            DECL_HAS_VALUE_EXPR_P (gnu_decl) = 1;
            TREE_STATIC (gnu_decl) = global_bindings_p ();
            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 type is an unconstrained array or
           any object whose type is a dummy type or void.  */
        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 an alignment.  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));

            /* No point in changing the type if there is an address clause
               as the final type of the object will be a reference type.  */
            if (Present (Address_Clause (gnat_entity)))
              align = 0;
            else
              {
                tree orig_type = gnu_type;

                gnu_type
                  = maybe_pad_type (gnu_type, NULL_TREE, align, gnat_entity,
                                    false, 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_type && !DECL_P (TYPE_NAME (gnu_type)))
                  create_type_decl (TYPE_NAME (gnu_type), gnu_type, true,
                                    debug_info_p, gnat_entity);
              }
          }

        /* If we are defining the object, see if it has a Size 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 discriminant.  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
                        && 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 isn't constant and we are at global level, call
               elaborate_expression_1 to make a variable for it rather than
               calculating it each time.  */
            if (!TREE_CONSTANT (gnu_size) && global_bindings_p ())
              gnu_size = elaborate_expression_1 (gnu_size, gnat_entity,
                                                 "SIZE", definition, false);
          }

        /* If the size is zero byte, make it one byte since some linkers have
           troubles 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 (gnat_type)
            && No (Renamed_Object (gnat_entity))
            && No (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_Or_VFA (gnat_entity)
                || (!Optimize_Alignment_Space (gnat_entity)
                    && kind != E_Exception
                    && kind != E_Out_Parameter
                    && Is_Composite_Type (gnat_type)
                    && !Is_Constr_Subt_For_UN_Aliased (gnat_type)
                    && !Is_Exported (gnat_entity)
                    && !imported_p
                    && No (Renamed_Object (gnat_entity))
                    && No (Address_Clause (gnat_entity))))
            && TREE_CODE (TYPE_SIZE (gnu_type)) == INTEGER_CST)
          {
            unsigned int size_cap, align_cap;

            /* No point in promoting the alignment if this doesn't prevent
               BLKmode access to the object, in particular block copy, as
               this will for example disable the NRV optimization for it.
               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.  */
            if (Is_Atomic_Or_VFA (gnat_entity))
              {
                size_cap = UINT_MAX;
                align_cap = BIGGEST_ALIGNMENT;
              }
            else
              {
                size_cap = MAX_FIXED_MODE_SIZE;
                align_cap = get_mode_alignment (ptr_mode);
              }

            if (!tree_fits_uhwi_p (TYPE_SIZE (gnu_type))
                || compare_tree_int (TYPE_SIZE (gnu_type), size_cap) > 0)
              align = 0;
            else if (compare_tree_int (TYPE_SIZE (gnu_type), align_cap) > 0)
              align = align_cap;
            else
              align = ceil_pow2 (tree_to_uhwi (TYPE_SIZE (gnu_type)));

            /* 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_type (gnu_inner, gnat_entity, true);
          }

        /* If this is an aliased object with an unconstrained array nominal
           subtype, make a type that includes the template.  We will either
           allocate or create a variable of that type, see below.  */
        if (Is_Constr_Subt_For_UN_Aliased (gnat_type)
            && Is_Array_Type (Underlying_Type (gnat_type))
            && !type_annotate_only)
          {
            tree gnu_array = gnat_to_gnu_type (Base_Type (gnat_type));
            gnu_type
              = build_unc_object_type_from_ptr (TREE_TYPE (gnu_array),
                                                gnu_type,
                                                concat_name (gnu_entity_name,
                                                             "UNC"),
                                                debug_info_p);
          }

        /* ??? If this is an object of CW type initialized to a value, try to
           ensure that the object is sufficient aligned for this value, but
           without pessimizing the allocation.  This is a kludge necessary
           because we don't support dynamic alignment.  */
        if (align == 0
            && Ekind (gnat_type) == E_Class_Wide_Subtype
            && No (Renamed_Object (gnat_entity))
            && No (Address_Clause (gnat_entity)))
          align = get_target_system_allocator_alignment () * BITS_PER_UNIT;

#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)
          {
            tree orig_type = gnu_type;

            gnu_type = maybe_pad_type (gnu_type, gnu_size, align, gnat_entity,
                                       false, 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_type && !DECL_P (TYPE_NAME (gnu_type)))
              create_type_decl (TYPE_NAME (gnu_type), gnu_type, true,
                                debug_info_p, gnat_entity);
          }

        /* Now check if the type of the object allows atomic access.  */
        if (Is_Atomic_Or_VFA (gnat_entity))
          check_ok_for_atomic_type (gnu_type, gnat_entity, false);

        /* If this is a renaming, avoid as much as possible to create a new
           object.  However, in some cases, creating it is required because
           renaming can be applied to objects that are not names in Ada.
           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)))
          {
            /* 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
                 && TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_expr, 0))))
                /* Strip useless conversions around the object.  */
                || gnat_useless_type_conversion (gnu_expr))
              {
                gnu_expr = TREE_OPERAND (gnu_expr, 0);
                gnu_type = TREE_TYPE (gnu_expr);
              }

            /* Or else, if the renamed object has an unconstrained type with
               default discriminant, use the padded type.  */
            else if (type_is_padding_self_referential (TREE_TYPE (gnu_expr)))
              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.  Therefore, it can be the
               inner object of a constant renaming and the renaming must be
               fully instantiated, i.e. it cannot be a reference to (part of)
               an existing object.  And treat other rvalues (addresses, null
               expressions, constructors and literals) the same way.  */
            tree inner = gnu_expr;
            while (handled_component_p (inner) || CONVERT_EXPR_P (inner))
              inner = TREE_OPERAND (inner, 0);
            /* Expand_Dispatching_Call can prepend a comparison of the tags
               before the call to "=".  */
            if (TREE_CODE (inner) == TRUTH_ANDIF_EXPR
                || TREE_CODE (inner) == COMPOUND_EXPR)
              inner = TREE_OPERAND (inner, 1);
            if ((TREE_CODE (inner) == CALL_EXPR
                 && !call_is_atomic_load (inner))
                || TREE_CODE (inner) == ADDR_EXPR
                || TREE_CODE (inner) == NULL_EXPR
                || TREE_CODE (inner) == PLUS_EXPR
                || TREE_CODE (inner) == CONSTRUCTOR
                || CONSTANT_CLASS_P (inner)
                /* We need to detect the case where a temporary is created to
                   hold the return value, since we cannot safely rename it at
                   top level as it lives only in the elaboration routine.  */
                || (TREE_CODE (inner) == VAR_DECL
                    && DECL_RETURN_VALUE_P (inner))
                /* We also need to detect the case where the front-end creates
                   a dangling 'reference to a function call at top level and
                   substitutes it in the renaming, for example:

                     q__b : boolean renames r__f.e (1);

                   can be rewritten into:

                     q__R1s : constant q__A2s := r__f'reference;
                     [...]
                     q__b : boolean renames q__R1s.all.e (1);

                   We cannot safely rename the rewritten expression since the
                   underlying object lives only in the elaboration routine.  */
                || (TREE_CODE (inner) == INDIRECT_REF
                    && (inner
                          = remove_conversions (TREE_OPERAND (inner, 0), true))
                    && TREE_CODE (inner) == VAR_DECL
                    && DECL_RETURN_VALUE_P (inner)))
              ;

            /* Case 2: if the renaming entity need not be materialized, use
               the elaborated renamed expression for the renaming.  But this
               means that the caller is responsible for evaluating the address
               of the renaming in the correct place for the definition case to
               instantiate the SAVE_EXPRs.  */
            else if (!Materialize_Entity (gnat_entity))
              {
                tree init = NULL_TREE;

                gnu_decl
                  = elaborate_reference (gnu_expr, gnat_entity, definition,
                                         &init);

                /* We cannot evaluate the first arm of a COMPOUND_EXPR in the
                   correct place for this case.  */
                gcc_assert (!init);

                /* No DECL_EXPR will be created so the expression needs to be
                   marked manually because it will likely be shared.  */
                if (global_bindings_p ())
                  MARK_VISITED (gnu_decl);

                /* This assertion will fail if the renamed object isn't aligned
                   enough as to make it possible to honor the alignment set on
                   the renaming.  */
                if (align)
                  {
                    unsigned int ralign = DECL_P (gnu_decl)
                                          ? DECL_ALIGN (gnu_decl)
                                          : TYPE_ALIGN (TREE_TYPE (gnu_decl));
                    gcc_assert (ralign >= align);
                  }

                /* The expression might not be a DECL so save it manually.  */
                save_gnu_tree (gnat_entity, gnu_decl, true);
                saved = true;
                annotate_object (gnat_entity, gnu_type, NULL_TREE, false);
                break;
              }

            /* Case 3: otherwise, make a constant pointer to the object we
               are renaming and attach the object to the pointer after it is
               elaborated.  The object will be referenced directly instead
               of indirectly via the pointer to avoid aliasing problems with
               non-addressable entities.  The pointer is called a "renaming"
               pointer in this case.  Note that we also need to preserve the
               volatility of the renamed object through the indirection.  */
            else
              {
                tree init = NULL_TREE;

                if (TREE_THIS_VOLATILE (gnu_expr) && !TYPE_VOLATILE (gnu_type))
                  gnu_type
                    = change_qualified_type (gnu_type, TYPE_QUAL_VOLATILE);
                gnu_type = build_reference_type (gnu_type);
                used_by_ref = true;
                const_flag = true;
                volatile_flag = false;
                inner_const_flag = TREE_READONLY (gnu_expr);
                gnu_size = NULL_TREE;

                renamed_obj
                  = elaborate_reference (gnu_expr, gnat_entity, definition,
                                         &init);

                /* The expression needs to be marked manually because it will
                   likely be shared, even for a definition since the ADDR_EXPR
                   built below can cause the first few nodes to be folded.  */
                if (global_bindings_p ())
                  MARK_VISITED (renamed_obj);

                if (type_annotate_only
                    && TREE_CODE (renamed_obj) == ERROR_MARK)
                  gnu_expr = NULL_TREE;
                else
                  {
                    gnu_expr
                      = build_unary_op (ADDR_EXPR, gnu_type, renamed_obj);
                    if (init)
                      gnu_expr
                        = build_compound_expr (TREE_TYPE (gnu_expr), init,
                                               gnu_expr);
                  }
              }
          }

        /* 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 above.  */
                || (TYPE_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_PADDING_P (gnu_type)
                ? TYPE_FIELDS (TREE_TYPE (TYPE_FIELDS (gnu_type)))
                : TYPE_FIELDS (gnu_type);
            vec<constructor_elt, va_gc> *v;
            vec_alloc (v, 1);
            tree t = build_template (TREE_TYPE (template_field),
                                     TREE_TYPE (DECL_CHAIN (template_field)),
                                     NULL_TREE);
            CONSTRUCTOR_APPEND_ELT (v, template_field, t);
            gnu_expr = gnat_build_constructor (gnu_type, v);
          }

        /* Convert the expression to the type of the object if need be.  */
        if (gnu_expr && initial_value_needs_conversion (gnu_type, gnu_expr))
          gnu_expr = convert (gnu_type, gnu_expr);

        /* If this is a pointer that doesn't have an initializing expression,
           initialize it to NULL, unless the object is declared imported as
           per RM B.1(24).  */
        if (definition
            && (POINTER_TYPE_P (gnu_type) || TYPE_IS_FAT_POINTER_P (gnu_type))
            && !gnu_expr
            && !Is_Imported (gnat_entity))
          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)))
          {
            const Node_Id gnat_clause = Address_Clause (gnat_entity);
            Node_Id gnat_address = Expression (gnat_clause);
            tree gnu_address
              = present_gnu_tree (gnat_entity)
                ? get_gnu_tree (gnat_entity) : gnat_to_gnu (gnat_address);

            save_gnu_tree (gnat_entity, NULL_TREE, false);

            /* Convert the type of the object to a reference type that can
               alias everything as per RM 13.3(19).  */
            if (volatile_flag && !TYPE_VOLATILE (gnu_type))
              gnu_type = change_qualified_type (gnu_type, TYPE_QUAL_VOLATILE);
            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 (gnat_address));
            volatile_flag = false;
            gnu_size = NULL_TREE;

            /* If this is an aliased object with an unconstrained array nominal
               subtype, then it can overlay only another aliased object with an
               unconstrained array nominal subtype and compatible template.  */
            if (Is_Constr_Subt_For_UN_Aliased (gnat_type)
                && Is_Array_Type (Underlying_Type (gnat_type))
                && !type_annotate_only)
              {
                tree rec_type = TREE_TYPE (gnu_type);
                tree off = byte_position (DECL_CHAIN (TYPE_FIELDS (rec_type)));

                /* This is the pattern built for a regular object.  */
                if (TREE_CODE (gnu_address) == POINTER_PLUS_EXPR
                    && TREE_OPERAND (gnu_address, 1) == off)
                  gnu_address = TREE_OPERAND (gnu_address, 0);
                /* This is the pattern built for an overaligned object.  */
                else if (TREE_CODE (gnu_address) == POINTER_PLUS_EXPR
                         && TREE_CODE (TREE_OPERAND (gnu_address, 1))
                            == PLUS_EXPR
                         && TREE_OPERAND (TREE_OPERAND (gnu_address, 1), 1)
                            == off)
                  gnu_address
                    = build2 (POINTER_PLUS_EXPR, gnu_type,
                              TREE_OPERAND (gnu_address, 0),
                              TREE_OPERAND (TREE_OPERAND (gnu_address, 1), 0));
                else
                  {
                    post_error_ne ("aliased object& with unconstrained array "
                                   "nominal subtype", gnat_clause,
                                   gnat_entity);
                    post_error ("\\can overlay only aliased object with "
                                "compatible subtype", gnat_clause);
                  }
              }

            /* 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 (INIT_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)))
            || (imported_p && Has_Stdcall_Convention (gnat_entity)))
          {
            /* Convert the type of the object to a reference type that can
               alias everything as per RM 13.3(19).  */
            if (volatile_flag && !TYPE_VOLATILE (gnu_type))
              gnu_type = change_qualified_type (gnu_type, TYPE_QUAL_VOLATILE);
            gnu_type
              = build_reference_type_for_mode (gnu_type, ptr_mode, true);
            used_by_ref = true;
            const_flag = false;
            volatile_flag = false;
            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;
                  }
              }
          }

        /* 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_flag)
            || (gnu_size
                && !allocatable_size_p (convert (sizetype,
                                                 size_binop
                                                 (CEIL_DIV_EXPR, gnu_size,
                                                  bitsize_unit_node)),
                                        global_bindings_p ()
                                        || !definition
                                        || static_flag)))
          {
            if (volatile_flag && !TYPE_VOLATILE (gnu_type))
              gnu_type = change_qualified_type (gnu_type, TYPE_QUAL_VOLATILE);
            gnu_type = build_reference_type (gnu_type);
            used_by_ref = true;
            const_flag = true;
            volatile_flag = false;
            gnu_size = NULL_TREE;

            /* 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 && !imported_p)
              {
                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 (DECL_CHAIN (TYPE_FIELDS (gnu_alloc_type)));

                    if (TREE_CODE (gnu_expr) == CONSTRUCTOR
                        && CONSTRUCTOR_NELTS (gnu_expr) == 1)
                      gnu_expr = NULL_TREE;
                    else
                      gnu_expr
                        = build_component_ref
                            (gnu_expr,
                             DECL_CHAIN (TYPE_FIELDS (TREE_TYPE (gnu_expr))),
                             false);
                  }

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

                gnu_expr
                  = build_allocator (gnu_alloc_type, gnu_expr, gnu_type,
                                     Empty, Empty, gnat_entity, mutable_p);
              }
            else
              gnu_expr = NULL_TREE;
          }

        /* 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 (definition
            && TYPE_ALIGN (gnu_type) > BIGGEST_ALIGNMENT
            && !imported_p
            && !static_flag
            && !global_bindings_p ())
          {
            /* 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, gnat_entity);
            tree gnu_new_var
              = create_var_decl (create_concat_name (gnat_entity, "ALIGN"),
                                 NULL_TREE, gnu_new_type, NULL_TREE,
                                 false, false, false, false, false,
                                 true, debug_info_p && definition, NULL,
                                 gnat_entity);

            /* Initialize the aligned field if we have an initializer.  */
            if (gnu_expr)
              add_stmt_with_node
                (build_binary_op (INIT_EXPR, NULL_TREE,
                                  build_component_ref
                                  (gnu_new_var, 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, NULL_TREE,
                 build_component_ref (gnu_new_var, TYPE_FIELDS (gnu_new_type),
                                      false));
            TREE_CONSTANT (gnu_expr) = 1;

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

        /* If this is an aliased object with an unconstrained array nominal
           subtype, we make its type a thin reference, i.e. the reference
           counterpart of a thin pointer, so it points to the array part.
           This is aimed to make it easier for the debugger to decode the
           object.  Note that we have to do it this late because of the
           couple of allocation adjustments that might be made above.  */
        if (Is_Constr_Subt_For_UN_Aliased (gnat_type)
            && Is_Array_Type (Underlying_Type (gnat_type))
            && !type_annotate_only)
          {
            /* In case the object with the template has already been allocated
               just above, we have nothing to do here.  */
            if (!TYPE_IS_THIN_POINTER_P (gnu_type))
              {
                /* This variable is a GNAT encoding used by Workbench: let it
                   go through the debugging information but mark it as
                   artificial: users are not interested in it.  */
                tree gnu_unc_var
                   = create_var_decl (concat_name (gnu_entity_name, "UNC"),
                                      NULL_TREE, gnu_type, gnu_expr,
                                      const_flag, Is_Public (gnat_entity),
                                      imported_p || !definition, static_flag,
                                      volatile_flag, true,
                                      debug_info_p && definition,
                                      NULL, gnat_entity);
                gnu_expr = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_unc_var);
                TREE_CONSTANT (gnu_expr) = 1;

                used_by_ref = true;
                const_flag = true;
                volatile_flag = false;
                inner_const_flag = TREE_READONLY (gnu_unc_var);
                gnu_size = NULL_TREE;
              }

            tree gnu_array = gnat_to_gnu_type (Base_Type (gnat_type));
            gnu_type
              = build_reference_type (TYPE_OBJECT_RECORD_TYPE (gnu_array));
          }

        /* Convert the expression to the type of the object if need be.  */
        if (gnu_expr && initial_value_needs_conversion (gnu_type, gnu_expr))
          gnu_expr = convert (gnu_type, gnu_expr);

        /* If this name is external or a name was specified, use it, but don't
           use the Interface_Name with an address clause (see cd30005).  */
        if ((Is_Public (gnat_entity) && !Is_Imported (gnat_entity))
            || (Present (Interface_Name (gnat_entity))
                && No (Address_Clause (gnat_entity))))
          gnu_ext_name = create_concat_name (gnat_entity, NULL);

        /* If this is an aggregate constant initialized to a constant, force it
           to be statically allocated.  This saves an initialization copy.  */
        if (!static_flag
            && const_flag
            && gnu_expr && TREE_CONSTANT (gnu_expr)
            && AGGREGATE_TYPE_P (gnu_type)
            && tree_fits_uhwi_p (TYPE_SIZE_UNIT (gnu_type))
            && !(TYPE_IS_PADDING_P (gnu_type)
                 && !tree_fits_uhwi_p (TYPE_SIZE_UNIT
                                       (TREE_TYPE (TYPE_FIELDS (gnu_type))))))
          static_flag = true;

        /* Deal with a pragma Linker_Section on a constant or variable.  */
        if ((kind == E_Constant || kind == E_Variable)
            && Present (Linker_Section_Pragma (gnat_entity)))
          prepend_one_attribute_pragma (&attr_list,
                                        Linker_Section_Pragma (gnat_entity));

        /* Now create the variable or the constant and set various flags.  */
        gnu_decl
          = create_var_decl (gnu_entity_name, gnu_ext_name, gnu_type,
                             gnu_expr, const_flag, Is_Public (gnat_entity),
                             imported_p || !definition, static_flag,
                             volatile_flag, artificial_p,
                             debug_info_p && definition, attr_list,
                             gnat_entity, !renamed_obj);
        DECL_BY_REF_P (gnu_decl) = used_by_ref;
        DECL_POINTS_TO_READONLY_P (gnu_decl) = used_by_ref && inner_const_flag;
        DECL_CAN_NEVER_BE_NULL_P (gnu_decl) = Can_Never_Be_Null (gnat_entity);

        /* If we are defining an Out parameter and optimization isn't enabled,
           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 live in memory so that it can be accessed from within the
           debugger through the PARM_DECL.  */
        if (kind == E_Out_Parameter
            && definition
            && debug_info_p
            && !optimize
            && !flag_generate_lto)
          {
            tree param = create_param_decl (gnu_entity_name, gnu_type);
            gnat_pushdecl (param, gnat_entity);
            SET_DECL_VALUE_EXPR (param, gnu_decl);
            DECL_HAS_VALUE_EXPR_P (param) = 1;
            DECL_IGNORED_P (gnu_decl) = 1;
            TREE_ADDRESSABLE (gnu_decl) = 1;
          }

        /* If this is a loop parameter, set the corresponding flag.  */
        else if (kind == E_Loop_Parameter)
          DECL_LOOP_PARM_P (gnu_decl) = 1;

        /* If this is a renaming pointer, attach the renamed object to it.  */
        if (renamed_obj)
          SET_DECL_RENAMED_OBJECT (gnu_decl, renamed_obj);

        /* If this is a constant and we are defining it or it generates a real
           symbol at the object level and we are referencing it, we may want
           or need to have a true variable to represent it:
             - if optimization isn't enabled, for debugging purposes,
             - if the constant is public and not overlaid on something else,
             - if its address is taken,
             - if either itself or its type is aliased.  */
        if (TREE_CODE (gnu_decl) == CONST_DECL
            && (definition || Sloc (gnat_entity) > Standard_Location)
            && ((!optimize && debug_info_p)
                || (Is_Public (gnat_entity)
                    && No (Address_Clause (gnat_entity)))
                || Address_Taken (gnat_entity)
                || Is_Aliased (gnat_entity)
                || Is_Aliased (gnat_type)))
          {
            tree gnu_corr_var
              = create_var_decl (gnu_entity_name, gnu_ext_name, gnu_type,
                                 gnu_expr, true, Is_Public (gnat_entity),
                                 !definition, static_flag, volatile_flag,
                                 artificial_p, debug_info_p && definition,
                                 attr_list, gnat_entity, false);

            SET_DECL_CONST_CORRESPONDING_VAR (gnu_decl, gnu_corr_var);
          }

        /* If this is a constant, even if we don't need a true variable, we
           may need to avoid returning the initializer in every case.  That
           can happen for the address of a (constant) constructor because,
           upon dereferencing it, the constructor will be reinjected in the
           tree, which may not be valid in every case; see lvalue_required_p
           for more details.  */
        if (TREE_CODE (gnu_decl) == CONST_DECL)
          DECL_CONST_ADDRESS_P (gnu_decl) = constructor_address_p (gnu_expr);

        /* If this object is declared in a block that contains a block with an
           exception handler, and we aren't using the GCC exception mechanism,
           we must force this variable in memory in order to avoid an invalid
           optimization.  */
        if (Front_End_Exceptions ()
            && Has_Nested_Block_With_Handler (Scope (gnat_entity)))
          TREE_ADDRESSABLE (gnu_decl) = 1;

        /* If this is a local variable with non-BLKmode and aggregate type,
           and optimization isn't enabled, then force it in memory so that
           a register won't be allocated to it with possible subparts left
           uninitialized and reaching the register allocator.  */
        else if (TREE_CODE (gnu_decl) == VAR_DECL
                 && !DECL_EXTERNAL (gnu_decl)
                 && !TREE_STATIC (gnu_decl)
                 && DECL_MODE (gnu_decl) != BLKmode
                 && AGGREGATE_TYPE_P (TREE_TYPE (gnu_decl))
                 && !TYPE_IS_FAT_POINTER_P (TREE_TYPE (gnu_decl))
                 && !optimize)
          TREE_ADDRESSABLE (gnu_decl) = 1;

        /* If we are defining an object with variable size or an object with
           fixed size that will be dynamically allocated, and we are using the
           front-end setjmp/longjmp exception mechanism, update the setjmp
           buffer.  */
        if (definition
            && Exception_Mechanism == Front_End_SJLJ
            && get_block_jmpbuf_decl ()
            && DECL_SIZE_UNIT (gnu_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_n_expr
                              (update_setjmp_buf_decl, 1,
                               build_unary_op (ADDR_EXPR, NULL_TREE,
                                               get_block_jmpbuf_decl ())),
                              gnat_entity);

        /* Back-annotate Esize and Alignment of the object if not already
           known.  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 all confirming representation clauses.  */
        annotate_object (gnat_entity, TREE_TYPE (gnu_decl), gnu_object_size,
                         used_by_ref);
      }
      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 integer type.  */
      if (No (First_Literal (gnat_entity)))
        {
          if (esize == CHAR_TYPE_SIZE && flag_signed_char)
            gnu_type = make_signed_type (CHAR_TYPE_SIZE);
          else
            gnu_type = make_unsigned_type (esize);
          TYPE_NAME (gnu_type) = gnu_entity_name;

          /* Set TYPE_STRING_FLAG for 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;

          /* This flag is needed by the call just below.  */
          TYPE_ARTIFICIAL (gnu_type) = artificial_p;

          finish_character_type (gnu_type);
        }
      else
        {
          /* We have a list of enumeral constants in First_Literal.  We make a
             CONST_DECL for each one and build into GNU_LITERAL_LIST the list
             to be placed into TYPE_FIELDS.  Each node is itself a TREE_LIST
             whose TREE_VALUE is the literal name and whose TREE_PURPOSE is the
             value of the literal.  But when we have a regular boolean type, we
             simplify this a little by using a BOOLEAN_TYPE.  */
          const bool is_boolean = Is_Boolean_Type (gnat_entity)
                                  && !Has_Non_Standard_Rep (gnat_entity);
          const bool is_unsigned = Is_Unsigned_Type (gnat_entity);
          tree gnu_list = NULL_TREE;
          Entity_Id gnat_literal;

          gnu_type = make_node (is_boolean ? BOOLEAN_TYPE : ENUMERAL_TYPE);
          TYPE_PRECISION (gnu_type) = esize;
          TYPE_UNSIGNED (gnu_type) = is_unsigned;
          set_min_and_max_values_for_integral_type (gnu_type, esize,
                                                    TYPE_SIGN (gnu_type));
          process_attributes (&gnu_type, &attr_list, true, gnat_entity);
          layout_type (gnu_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);
              /* Do not generate debug info for individual enumerators.  */
              tree gnu_literal
                = create_var_decl (get_entity_name (gnat_literal), NULL_TREE,
                                   gnu_type, gnu_value, true, false, false,
                                   false, false, artificial_p, false,
                                   NULL, gnat_literal);
              save_gnu_tree (gnat_literal, gnu_literal, false);
              gnu_list
                = tree_cons (DECL_NAME (gnu_literal), gnu_value, gnu_list);
            }

          if (!is_boolean)
            TYPE_VALUES (gnu_type) = nreverse (gnu_list);

          /* Note that the bounds are updated at the end of this function
             to avoid an infinite recursion since they refer to the type.  */
          goto discrete_type;
        }
      break;

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

    case E_Ordinary_Fixed_Point_Type:
    case E_Decimal_Fixed_Point_Type:
      {
        /* Small_Value is the scale factor.  */
        const Ureal gnat_small_value = Small_Value (gnat_entity);
        tree scale_factor = NULL_TREE;

        gnu_type = make_signed_type (esize);

        /* Try to decode the scale factor and to save it for the fixed-point
           types debug hook.  */

        /* There are various ways to describe the scale factor, however there
           are cases where back-end internals cannot hold it.  In such cases,
           we output invalid scale factor for such cases (i.e. the 0/0
           rational constant) but we expect GNAT to output GNAT encodings,
           then.  Thus, keep this in sync with
           Exp_Dbug.Is_Handled_Scale_Factor.  */

        /* When encoded as 1/2**N or 1/10**N, describe the scale factor as a
           binary or decimal scale: it is easier to read for humans.  */
        if (UI_Eq (Numerator (gnat_small_value), Uint_1)
            && (Rbase (gnat_small_value) == 2
                || Rbase (gnat_small_value) == 10))
          {
            /* Given RM restrictions on 'Small values, we assume here that
               the denominator fits in an int.  */
            const tree base = build_int_cst (integer_type_node,
                                             Rbase (gnat_small_value));
            const tree exponent
              = build_int_cst (integer_type_node,
                               UI_To_Int (Denominator (gnat_small_value)));
            scale_factor
              = build2 (RDIV_EXPR, integer_type_node,
                        integer_one_node,
                        build2 (POWER_EXPR, integer_type_node,
                                base, exponent));
          }

        /* Default to arbitrary scale factors descriptions.  */
        else
          {
            const Uint num = Norm_Num (gnat_small_value);
            const Uint den = Norm_Den (gnat_small_value);

            if (UI_Is_In_Int_Range (num) && UI_Is_In_Int_Range (den))
              {
                const tree gnu_num
                  = build_int_cst (integer_type_node,
                                   UI_To_Int (Norm_Num (gnat_small_value)));
                const tree gnu_den
                  = build_int_cst (integer_type_node,
                                   UI_To_Int (Norm_Den (gnat_small_value)));
                scale_factor = build2 (RDIV_EXPR, integer_type_node,
                                       gnu_num, gnu_den);
              }
            else
              /* If compiler internals cannot represent arbitrary scale
                 factors, output an invalid scale factor so that debugger
                 don't try to handle them but so that we still have a type
                 in the output.  Note that GNAT  */
              scale_factor = integer_zero_node;
          }

        TYPE_FIXED_POINT_P (gnu_type) = 1;
        SET_TYPE_SCALE_FACTOR (gnu_type, scale_factor);
      }
      goto discrete_type;

    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.  */
        tree gnu_modulus, gnu_high = NULL_TREE;

        /* Packed Array Impl. Types are supposed to be subtypes only.  */
        gcc_assert (!Is_Packed_Array_Impl_Type (gnat_entity));

        gnu_type = make_unsigned_type (esize);

        /* 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,
                                    build_int_cst (gnu_type, 1));
          }

        /* If the upper bound is not maximal, make an extra subtype.  */
        if (gnu_high
            && !tree_int_cst_equal (gnu_high, TYPE_MAX_VALUE (gnu_type)))
          {
            tree gnu_subtype = make_unsigned_type (esize);
            SET_TYPE_RM_MAX_VALUE (gnu_subtype, gnu_high);
            TREE_TYPE (gnu_subtype) = gnu_type;
            TYPE_EXTRA_SUBTYPE_P (gnu_subtype) = 1;
            TYPE_NAME (gnu_type) = create_concat_name (gnat_entity, "UMT");
            gnu_type = gnu_subtype;
          }
      }
      goto discrete_type;

    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 create_range_type since we would like each subtype
         node to be distinct.  ??? Historically this was in preparation for
         when memory aliasing is implemented, but that's obsolete now given
         the call to relate_alias_sets below.

         The TREE_TYPE field of the INTEGER_TYPE points to the base 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
         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, false);

      /* Set the precision to the Esize except for bit-packed arrays.  */
      if (Is_Packed_Array_Impl_Type (gnat_entity)
          && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)))
        esize = UI_To_Int (RM_Size (gnat_entity));

      /* First subtypes of Character are treated as Character; otherwise
         this should be an unsigned type if the base type is unsigned or
         if the lower bound is constant and non-negative or if the type
         is biased.  However, even if the lower bound is constant and
         non-negative, we use a signed type for a subtype with the same
         size as its signed base type, because this eliminates useless
         conversions to it and gives more leeway to the optimizer; but
         this means that we will need to explicitly test for this case
         when we change the representation based on the RM size.  */
      if (kind == E_Enumeration_Subtype
          && No (First_Literal (Etype (gnat_entity)))
          && Esize (gnat_entity) == RM_Size (gnat_entity)
          && esize == CHAR_TYPE_SIZE
          && flag_signed_char)
        gnu_type = make_signed_type (CHAR_TYPE_SIZE);
      else if (Is_Unsigned_Type (Underlying_Type (Etype (gnat_entity)))
               || (Esize (Etype (gnat_entity)) != Esize (gnat_entity)
                   && Is_Unsigned_Type (gnat_entity))
               || Has_Biased_Representation (gnat_entity))
        gnu_type = make_unsigned_type (esize);
      else
        gnu_type = make_signed_type (esize);
      TREE_TYPE (gnu_type) = get_unpadded_type (Etype (gnat_entity));

      SET_TYPE_RM_MIN_VALUE
        (gnu_type, elaborate_expression (Type_Low_Bound (gnat_entity),
                                         gnat_entity, "L", definition, true,
                                         debug_info_p));

      SET_TYPE_RM_MAX_VALUE
        (gnu_type, elaborate_expression (Type_High_Bound (gnat_entity),
                                         gnat_entity, "U", definition, true,
                                         debug_info_p));

      TYPE_BIASED_REPRESENTATION_P (gnu_type)
        = Has_Biased_Representation (gnat_entity);

      /* Do the same processing for Character subtypes as for types.  */
      if (TYPE_STRING_FLAG (TREE_TYPE (gnu_type)))
        {
          TYPE_NAME (gnu_type) = gnu_entity_name;
          TYPE_STRING_FLAG (gnu_type) = 1;
          TYPE_ARTIFICIAL (gnu_type) = artificial_p;
          finish_character_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);

      /* 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;
        }

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

      /* For a packed array, make the original array type a parallel/debug
         type.  */
      if (debug_info_p && Is_Packed_Array_Impl_Type (gnat_entity))
        associate_original_type_to_packed_array (gnu_type, gnat_entity);

    discrete_type:

      /* We have to handle clauses that under-align the type specially.  */
      if ((Present (Alignment_Clause (gnat_entity))
           || (Is_Packed_Array_Impl_Type (gnat_entity)
               && Present
                  (Alignment_Clause (Original_Array_Type (gnat_entity)))))
          && UI_Is_In_Int_Range (Alignment (gnat_entity)))
        {
          align = UI_To_Int (Alignment (gnat_entity)) * BITS_PER_UNIT;
          if (align >= TYPE_ALIGN (gnu_type))
            align = 0;
        }

      /* If the type we are dealing with represents a bit-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 up
         the modular type in an enclosing record type.  */
      if (Is_Packed_Array_Impl_Type (gnat_entity)
          && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)))
        {
          tree gnu_field_type, gnu_field;

          /* Set the RM size before wrapping up the original type.  */
          SET_TYPE_RM_SIZE (gnu_type,
                            UI_To_gnu (RM_Size (gnat_entity), bitsizetype));
          TYPE_PACKED_ARRAY_TYPE_P (gnu_type) = 1;

          /* Strip the ___XP suffix for standard DWARF.  */
          if (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
            gnu_entity_name = TYPE_NAME (gnu_type);

          /* Create a stripped-down declaration, mainly for debugging.  */
          create_type_decl (gnu_entity_name, gnu_type, true, debug_info_p,
                            gnat_entity);

          /* Now save it and build the enclosing record type.  */
          gnu_field_type = gnu_type;

          gnu_type = make_node (RECORD_TYPE);
          TYPE_NAME (gnu_type) = create_concat_name (gnat_entity, "JM");
          TYPE_PACKED (gnu_type) = 1;
          TYPE_SIZE (gnu_type) = TYPE_SIZE (gnu_field_type);
          TYPE_SIZE_UNIT (gnu_type) = TYPE_SIZE_UNIT (gnu_field_type);
          SET_TYPE_ADA_SIZE (gnu_type, TYPE_RM_SIZE (gnu_field_type));

          /* Propagate the alignment of the modular type to the record type,
             unless there is an alignment clause that under-aligns the type.
             This means that bit-packed arrays are given "ceil" alignment for
             their size by default, which may seem counter-intuitive but makes
             it possible to overlay them on modular types easily.  */
          SET_TYPE_ALIGN (gnu_type,
                          align > 0 ? align : TYPE_ALIGN (gnu_field_type));

          /* Propagate the reverse storage order flag to the record type so
             that the required byte swapping is performed when retrieving the
             enclosed modular value.  */
          TYPE_REVERSE_STORAGE_ORDER (gnu_type)
            = Reverse_Storage_Order (Original_Array_Type (gnat_entity));

          relate_alias_sets (gnu_type, gnu_field_type, ALIAS_SET_COPY);

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

          /* We will output additional debug info manually below.  */
          finish_record_type (gnu_type, gnu_field, 2, false);
          compute_record_mode (gnu_type);
          TYPE_JUSTIFIED_MODULAR_P (gnu_type) = 1;

          if (debug_info_p)
            {
              /* Make the original array type a parallel/debug type.  */
              associate_original_type_to_packed_array (gnu_type, gnat_entity);

              /* Since GNU_TYPE is a padding type around the packed array
                 implementation type, the padded type is its debug type.  */
              if (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
                SET_TYPE_DEBUG_TYPE (gnu_type, gnu_field_type);
            }
        }

      /* 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 misalign the
         latter; we reuse the padding machinery for this purpose.  */
      else if (align > 0)
        {
          tree gnu_size = UI_To_gnu (RM_Size (gnat_entity), bitsizetype);

          /* Set the RM size before wrapping the type.  */
          SET_TYPE_RM_SIZE (gnu_type, gnu_size);

          gnu_type
            = maybe_pad_type (gnu_type, TYPE_SIZE (gnu_type), align,
                              gnat_entity, false, true, definition, false);

          TYPE_PACKED (gnu_type) = 1;
          SET_TYPE_ADA_SIZE (gnu_type, gnu_size);
        }

      break;

    case E_Floating_Point_Type:
      /* 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:
      /* See the E_Signed_Integer_Subtype case for the rationale.  */
      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, false);

      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_GCC_MIN_VALUE (gnu_type)
        = TYPE_GCC_MIN_VALUE (TREE_TYPE (gnu_type));
      TYPE_GCC_MAX_VALUE (gnu_type)
        = TYPE_GCC_MAX_VALUE (TREE_TYPE (gnu_type));
      layout_type (gnu_type);

      SET_TYPE_RM_MIN_VALUE
        (gnu_type, elaborate_expression (Type_Low_Bound (gnat_entity),
                                         gnat_entity, "L", definition, true,
                                         debug_info_p));

      SET_TYPE_RM_MAX_VALUE
        (gnu_type, elaborate_expression (Type_High_Bound (gnat_entity),
                                         gnat_entity, "U", definition, true,
                                         debug_info_p));

      /* 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);

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

      /* Array 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_Array_Type:
      {
        const bool convention_fortran_p
          = (Convention (gnat_entity) == Convention_Fortran);
        const int ndim = Number_Dimensions (gnat_entity);
        tree gnu_template_type;
        tree gnu_ptr_template;
        tree gnu_template_reference, gnu_template_fields, gnu_fat_type;
        tree *gnu_index_types = XALLOCAVEC (tree, ndim);
        tree *gnu_temp_fields = XALLOCAVEC (tree, ndim);
        tree gnu_max_size = size_one_node, gnu_max_size_unit, tem, t;
        Entity_Id gnat_index, gnat_name;
        int index;
        tree comp_type;

        /* Create the type for the component now, as it simplifies breaking
           type reference loops.  */
        comp_type
          = gnat_to_gnu_component_type (gnat_entity, definition, debug_info_p);
        if (present_gnu_tree (gnat_entity))
          {
            /* As a side effect, the type may have been translated.  */
            maybe_present = true;
            break;
          }

        /* We complete an existing dummy fat pointer type in place.  This both
           avoids further complex adjustments in update_pointer_to and yields
           better debugging information in DWARF by leveraging the support for
           incomplete declarations of "tagged" types in the DWARF back-end.  */
        gnu_type = get_dummy_type (gnat_entity);
        if (gnu_type && TYPE_POINTER_TO (gnu_type))
          {
            gnu_fat_type = TYPE_MAIN_VARIANT (TYPE_POINTER_TO (gnu_type));
            TYPE_NAME (gnu_fat_type) = NULL_TREE;
            /* Save the contents of the dummy type for update_pointer_to.  */
            TYPE_POINTER_TO (gnu_type) = copy_type (gnu_fat_type);
            gnu_ptr_template =
              TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_fat_type)));
            gnu_template_type = TREE_TYPE (gnu_ptr_template);
          }
        else
          {
            gnu_fat_type = make_node (RECORD_TYPE);
            gnu_template_type = make_node (RECORD_TYPE);
            gnu_ptr_template = build_pointer_type (gnu_template_type);
          }

        /* 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
          = create_field_decl (get_identifier ("P_ARRAY"), ptr_type_node,
                               gnu_fat_type, NULL_TREE, NULL_TREE, 0, 0);
        DECL_CHAIN (tem)
          = create_field_decl (get_identifier ("P_BOUNDS"), gnu_ptr_template,
                               gnu_fat_type, NULL_TREE, NULL_TREE, 0, 0);

        if (COMPLETE_TYPE_P (gnu_fat_type))
          {
            /* We are going to lay it out again so reset the alias set.  */
            alias_set_type alias_set = TYPE_ALIAS_SET (gnu_fat_type);
            TYPE_ALIAS_SET (gnu_fat_type) = -1;
            finish_fat_pointer_type (gnu_fat_type, tem);
            TYPE_ALIAS_SET (gnu_fat_type) = alias_set;
            for (t = gnu_fat_type; t; t = TYPE_NEXT_VARIANT (t))
              {
                TYPE_FIELDS (t) = tem;
                SET_TYPE_UNCONSTRAINED_ARRAY (t, gnu_type);
              }
          }
        else
          {
            finish_fat_pointer_type (gnu_fat_type, tem);
            SET_TYPE_UNCONSTRAINED_ARRAY (gnu_fat_type, gnu_type);
          }

        /* 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),
                      DECL_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;
        TREE_THIS_NOTRAP (gnu_template_reference) = 1;

        /* Now create the GCC type for each index and add the fields for that
           index to the template.  */
        for (index = (convention_fortran_p ? ndim - 1 : 0),
             gnat_index = First_Index (gnat_entity);
             0 <= index && index < ndim;
             index += (convention_fortran_p ? - 1 : 1),
             gnat_index = Next_Index (gnat_index))
          {
            char field_name[16];
            tree gnu_index_type = get_unpadded_type (Etype (gnat_index));
            tree gnu_index_base_type
              = maybe_character_type (get_base_type (gnu_index_type));
            tree gnu_lb_field, gnu_hb_field, gnu_orig_min, gnu_orig_max;
            tree gnu_min, gnu_max, gnu_high;

            /* Make the FIELD_DECLs for the low and high bounds of this
               type and then make extractions of these fields from the
               template.  */
            sprintf (field_name, "LB%d", index);
            gnu_lb_field = create_field_decl (get_identifier (field_name),
                                              gnu_index_base_type,
                                              gnu_template_type, NULL_TREE,
                                              NULL_TREE, 0, 0);
            Sloc_to_locus (Sloc (gnat_entity),
                           &DECL_SOURCE_LOCATION (gnu_lb_field));

            field_name[0] = 'U';
            gnu_hb_field = create_field_decl (get_identifier (field_name),
                                              gnu_index_base_type,
                                              gnu_template_type, NULL_TREE,
                                              NULL_TREE, 0, 0);
            Sloc_to_locus (Sloc (gnat_entity),
                           &DECL_SOURCE_LOCATION (gnu_hb_field));

            gnu_temp_fields[index] = chainon (gnu_lb_field, gnu_hb_field);

            /* We can't use build_component_ref here since the template type
               isn't complete yet.  */
            gnu_orig_min = build3 (COMPONENT_REF, gnu_index_base_type,
                                   gnu_template_reference, gnu_lb_field,
                                   NULL_TREE);
            gnu_orig_max = build3 (COMPONENT_REF, gnu_index_base_type,
                                   gnu_template_reference, gnu_hb_field,
                                   NULL_TREE);
            TREE_READONLY (gnu_orig_min) = TREE_READONLY (gnu_orig_max) = 1;

            gnu_min = convert (sizetype, gnu_orig_min);
            gnu_max = convert (sizetype, gnu_orig_max);

            /* Compute the size of this dimension.  See the E_Array_Subtype
               case below for the rationale.  */
            gnu_high
              = build3 (COND_EXPR, sizetype,
                        build2 (GE_EXPR, boolean_type_node,
                                gnu_orig_max, gnu_orig_min),
                        gnu_max,
                        size_binop (MINUS_EXPR, gnu_min, size_one_node));

            /* Make a range type with the new range in the Ada base type.
               Then make an index type with the size range in sizetype.  */
            gnu_index_types[index]
              = create_index_type (gnu_min, gnu_high,
                                   create_range_type (gnu_index_base_type,
                                                      gnu_orig_min,
                                                      gnu_orig_max),
                                   gnat_entity);

            /* Update the maximum size of the array in elements.  */
            if (gnu_max_size)
              {
                tree gnu_min
                  = convert (sizetype, TYPE_MIN_VALUE (gnu_index_type));
                tree gnu_max
                  = convert (sizetype, TYPE_MAX_VALUE (gnu_index_type));
                tree gnu_this_max
                  = size_binop (PLUS_EXPR, size_one_node,
                                size_binop (MINUS_EXPR, gnu_max, gnu_min));

                if (TREE_CODE (gnu_this_max) == INTEGER_CST
                    && TREE_OVERFLOW (gnu_this_max))
                  gnu_max_size = NULL_TREE;
                else
                  gnu_max_size
                    = size_binop (MULT_EXPR, gnu_max_size, gnu_this_max);
              }

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

        /* Install all the fields into the template.  */
        TYPE_NAME (gnu_template_type)
          = create_concat_name (gnat_entity, "XUB");
        gnu_template_fields = NULL_TREE;
        for (index = 0; index < ndim; index++)
          gnu_template_fields
            = chainon (gnu_template_fields, gnu_temp_fields[index]);
        finish_record_type (gnu_template_type, gnu_template_fields, 0,
                            debug_info_p);
        TYPE_READONLY (gnu_template_type) = 1;

        /* 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 (comp_type)));

        /* Compute the maximum size of the array in units and bits.  */
        if (gnu_max_size)
          {
            gnu_max_size_unit = size_binop (MULT_EXPR, gnu_max_size,
                                            TYPE_SIZE_UNIT (comp_type));
            gnu_max_size = size_binop (MULT_EXPR,
                                       convert (bitsizetype, gnu_max_size),
                                       TYPE_SIZE (comp_type));
          }
        else
          gnu_max_size_unit = NULL_TREE;

        /* Now build the array type.  */
        tem = comp_type;
        for (index = ndim - 1; index >= 0; index--)
          {
            tem = build_nonshared_array_type (tem, gnu_index_types[index]);
            TYPE_MULTI_ARRAY_P (tem) = (index > 0);
            TYPE_CONVENTION_FORTRAN_P (tem) = convention_fortran_p;
            if (index == ndim - 1 && Reverse_Storage_Order (gnat_entity))
              set_reverse_storage_order_on_array_type (tem);
            if (array_type_has_nonaliased_component (tem, gnat_entity))
              set_nonaliased_component_on_array_type (tem);
          }

        /* If an alignment is specified, use it if valid.  But ignore it
           for the original type of packed array types.  If the alignment
           was requested with an explicit alignment clause, state so.  */
        if (No (Packed_Array_Impl_Type (gnat_entity))
            && Known_Alignment (gnat_entity))
          {
            SET_TYPE_ALIGN (tem,
                            validate_alignment (Alignment (gnat_entity),
                                                gnat_entity,
                                                TYPE_ALIGN (tem)));
            if (Present (Alignment_Clause (gnat_entity)))
              TYPE_USER_ALIGN (tem) = 1;
          }

        /* Tag top-level ARRAY_TYPE nodes for packed arrays and their
           implementation types as such so that the debug information back-end
           can output the appropriate description for them.  */
        TYPE_PACKED (tem)
          = (Is_Packed (gnat_entity)
             || Is_Packed_Array_Impl_Type (gnat_entity));

        if (Treat_As_Volatile (gnat_entity))
          tem = change_qualified_type (tem, TYPE_QUAL_VOLATILE);

        /* Adjust the type of the pointer-to-array field of the fat pointer
           and record the aliasing relationships if necessary.  */
        TREE_TYPE (TYPE_FIELDS (gnu_fat_type)) = build_pointer_type (tem);
        if (TYPE_ALIAS_SET_KNOWN_P (gnu_fat_type))
          record_component_aliases (gnu_fat_type);

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

        /* If the maximum size doesn't overflow, use it.  */
        if (gnu_max_size
            && 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))
          {
            TYPE_SIZE (tem) = size_binop (MIN_EXPR, gnu_max_size,
                                          TYPE_SIZE (tem));
            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,
                          artificial_p, debug_info_p, gnat_entity);

        /* If told to generate GNAT encodings for them (GDB rely on them at the
           moment): give the fat pointer type a name.  If this is a packed
           array, tell the debugger how to interpret the underlying bits.  */
        if (Present (Packed_Array_Impl_Type (gnat_entity)))
          gnat_name = Packed_Array_Impl_Type (gnat_entity);
        else
          gnat_name = gnat_entity;
        tree xup_name
          = (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
            ? get_entity_name (gnat_name)
            : create_concat_name (gnat_name, "XUP");
        create_type_decl (xup_name, gnu_fat_type, artificial_p, debug_info_p,
                          gnat_entity);

        /* Create the type to be designated by thin pointers: a record type for
           the array and its template.  We used to shift the fields to have the
           template at a negative offset, but this was somewhat of a kludge; we
           now shift thin pointer values explicitly but only those which have a
           TYPE_UNCONSTRAINED_ARRAY attached to the designated RECORD_TYPE.
           Note that GDB can handle standard DWARF information for them, so we
           don't have to name them as a GNAT encoding, except if specifically
           asked to.  */
        tree xut_name
          = (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
            ? get_entity_name (gnat_name)
            : create_concat_name (gnat_name, "XUT");
        tem = build_unc_object_type (gnu_template_type, tem, xut_name,
                                     debug_info_p);

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

    case E_Array_Subtype:

      /* This is the actual data type for array variables.  Multidimensional
         arrays are implemented as arrays of arrays.  Note that 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 = TYPE_MAIN_VARIANT (gnat_to_gnu_type (Etype (gnat_entity)));
      if (!Is_Constrained (gnat_entity))
        ;
      else
        {
          Entity_Id gnat_index, gnat_base_index;
          const bool convention_fortran_p
            = (Convention (gnat_entity) == Convention_Fortran);
          const int ndim = Number_Dimensions (gnat_entity);
          tree gnu_base_type = gnu_type;
          tree *gnu_index_types = XALLOCAVEC (tree, ndim);
          tree gnu_max_size = size_one_node, gnu_max_size_unit;
          bool need_index_type_struct = false;
          int index;

          /* First create the GCC type for each index and find out whether
             special types are needed for debugging information.  */
          for (index = (convention_fortran_p ? ndim - 1 : 0),
               gnat_index = First_Index (gnat_entity),
               gnat_base_index
                 = First_Index (Implementation_Base_Type (gnat_entity));
               0 <= index && index < ndim;
               index += (convention_fortran_p ? - 1 : 1),
               gnat_index = Next_Index (gnat_index),
               gnat_base_index = Next_Index (gnat_base_index))
            {
              tree gnu_index_type = get_unpadded_type (Etype (gnat_index));
              tree gnu_index_base_type
                = maybe_character_type (get_base_type (gnu_index_type));
              tree gnu_orig_min
                = convert (gnu_index_base_type,
                           TYPE_MIN_VALUE (gnu_index_type));
              tree gnu_orig_max
                = convert (gnu_index_base_type,
                           TYPE_MAX_VALUE (gnu_index_type));
              tree gnu_min = convert (sizetype, gnu_orig_min);
              tree gnu_max = convert (sizetype, gnu_orig_max);
              tree gnu_base_index_type
                = get_unpadded_type (Etype (gnat_base_index));
              tree gnu_base_index_base_type
                = maybe_character_type (get_base_type (gnu_base_index_type));
              tree gnu_base_orig_min
                = convert (gnu_base_index_base_type,
                           TYPE_MIN_VALUE (gnu_base_index_type));
              tree gnu_base_orig_max
                = convert (gnu_base_index_base_type,
                           TYPE_MAX_VALUE (gnu_base_index_type));
              tree gnu_high;

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

              /* Similarly, if one of the values overflows in sizetype and the
                 range is null, use 1..0 for the sizetype bounds.  */
              else if (TREE_CODE (gnu_min) == INTEGER_CST
                       && TREE_CODE (gnu_max) == INTEGER_CST
                       && (TREE_OVERFLOW (gnu_min) || TREE_OVERFLOW (gnu_max))
                       && tree_int_cst_lt (gnu_orig_max, gnu_orig_min))
                {
                  gnu_min = size_one_node;
                  gnu_max = size_zero_node;
                  gnu_high = gnu_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 indication.  */
              else if (TREE_CODE (gnu_min) == INTEGER_CST
                       && TREE_CODE (gnu_max) == INTEGER_CST
                       && TREE_OVERFLOW (gnu_min) && TREE_OVERFLOW (gnu_max)
                       && !TREE_OVERFLOW
                           (convert (sizetype,
                                     fold_build2 (MINUS_EXPR, gnu_index_type,
                                                  gnu_orig_max,
                                                  gnu_orig_min))))
                {
                  TREE_OVERFLOW (gnu_min) = 0;
                  TREE_OVERFLOW (gnu_max) = 0;
                  gnu_high = gnu_max;
                }

              /* Compute the size of this dimension in the general case.  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 type.  */
              else if ((Nkind (gnat_index) == N_Range
                        && cannot_be_superflat (gnat_index))
                       /* Bit-Packed Array Impl. Types are never superflat.  */
                       || (Is_Packed_Array_Impl_Type (gnat_entity)
                           && Is_Bit_Packed_Array
                              (Original_Array_Type (gnat_entity))))
                gnu_high = gnu_max;

              /* Otherwise, if the high bound is constant but the low bound is
                 not, we use the expression (hb >= lb) ? lb : hb + 1 for the
                 lower bound.  Note that the comparison must be done in the
                 original type to avoid any overflow during the conversion.  */
              else if (TREE_CODE (gnu_max) == INTEGER_CST
                       && TREE_CODE (gnu_min) != INTEGER_CST)
                {
                  gnu_high = gnu_max;
                  gnu_min
                    = build_cond_expr (sizetype,
                                       build_binary_op (GE_EXPR,
                                                        boolean_type_node,
                                                        gnu_orig_max,
                                                        gnu_orig_min),
                                       gnu_min,
                                       int_const_binop (PLUS_EXPR, gnu_max,
                                                        size_one_node));
                }

              /* Finally we use (hb >= lb) ? hb : lb - 1 for the upper bound
                 in all the other cases.  Note that, here as well as above,
                 the condition used in the comparison must be equivalent to
                 the condition (length != 0).  This is relied upon in order
                 to optimize array comparisons in compare_arrays.  Moreover
                 we use int_const_binop for the shift by 1 if the bound is
                 constant to avoid any unwanted overflow.  */
              else
                gnu_high
                  = build_cond_expr (sizetype,
                                     build_binary_op (GE_EXPR,
                                                      boolean_type_node,
                                                      gnu_orig_max,
                                                      gnu_orig_min),
                                     gnu_max,
                                     TREE_CODE (gnu_min) == INTEGER_CST
                                     ? int_const_binop (MINUS_EXPR, gnu_min,
                                                        size_one_node)
                                     : size_binop (MINUS_EXPR, gnu_min,
                                                   size_one_node));

              /* Reuse the index type for the range type.  Then make an index
                 type with the size range in sizetype.  */
              gnu_index_types[index]
                = create_index_type (gnu_min, gnu_high, gnu_index_type,
                                     gnat_entity);

              /* Update the maximum size of the array in elements.  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 (gnu_max_size)
                {
                  tree gnu_base_min = convert (sizetype, gnu_base_orig_min);
                  tree gnu_base_max = convert (sizetype, gnu_base_orig_max);
                  tree gnu_base_base_min
                    = convert (sizetype,
                               TYPE_MIN_VALUE (gnu_base_index_base_type));
                  tree gnu_base_base_max
                    = convert (sizetype,
                               TYPE_MAX_VALUE (gnu_base_index_base_type));

                  if (!CONTAINS_PLACEHOLDER_P (gnu_min)
                      || !(TREE_CODE (gnu_base_min) == INTEGER_CST
                           && !TREE_OVERFLOW (gnu_base_min)))
                    gnu_base_min = gnu_min;

                  if (!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))
                    gnu_max_size = NULL_TREE;
                  else
                    {
                      tree gnu_this_max;

                      /* Use int_const_binop if the bounds are constant to
                         avoid any unwanted overflow.  */
                      if (TREE_CODE (gnu_base_min) == INTEGER_CST
                          && TREE_CODE (gnu_base_max) == INTEGER_CST)
                        gnu_this_max
                          = int_const_binop (PLUS_EXPR, size_one_node,
                                             int_const_binop (MINUS_EXPR,
                                                              gnu_base_max,
                                                              gnu_base_min));
                      else
                        gnu_this_max
                          = size_binop (PLUS_EXPR, size_one_node,
                                        size_binop (MINUS_EXPR,
                                                    gnu_base_max,
                                                    gnu_base_min));

                      gnu_max_size
                        = size_binop (MULT_EXPR, gnu_max_size, gnu_this_max);
                    }
                }

              /* We need special types for debugging information to point to
                 the index types if they have variable bounds, are not integer
                 types, are biased or are wider than sizetype.  These are GNAT
                 encodings, so we have to include them only when all encodings
                 are requested.  */
              if ((TREE_CODE (gnu_orig_min) != INTEGER_CST
                   || TREE_CODE (gnu_orig_max) != INTEGER_CST
                   || TREE_CODE (gnu_index_type) != INTEGER_TYPE
                   || (TREE_TYPE (gnu_index_type)
                       && TREE_CODE (TREE_TYPE (gnu_index_type))
                          != INTEGER_TYPE)
                   || TYPE_BIASED_REPRESENTATION_P (gnu_index_type))
                  && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL)
                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_Impl_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 = ndim - 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_component_type (gnat_entity, definition,
                                                     debug_info_p);

              /* 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;
                }
            }

          /* Compute the maximum size of the array in units and bits.  */
          if (gnu_max_size)
            {
              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));
            }
          else
            gnu_max_size_unit = NULL_TREE;

          /* Now build the array type.  */
          for (index = ndim - 1; index >= 0; index --)
            {
              gnu_type = build_nonshared_array_type (gnu_type,
                                                     gnu_index_types[index]);
              TYPE_MULTI_ARRAY_P (gnu_type) = (index > 0);
              TYPE_CONVENTION_FORTRAN_P (gnu_type) = convention_fortran_p;
              if (index == ndim - 1 && Reverse_Storage_Order (gnat_entity))
                set_reverse_storage_order_on_array_type (gnu_type);
              if (array_type_has_nonaliased_component (gnu_type, gnat_entity))
                set_nonaliased_component_on_array_type (gnu_type);
            }

          /* Strip the ___XP suffix for standard DWARF.  */
          if (Is_Packed_Array_Impl_Type (gnat_entity)
              && gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
            {
              Entity_Id gnat_original_array_type
                = Underlying_Type (Original_Array_Type (gnat_entity));

              gnu_entity_name
                = get_entity_name (gnat_original_array_type);
            }

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

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

              for (gnu_arr_type = TREE_TYPE (gnu_type), index = 1;
                   TREE_CODE (gnu_arr_type) == ARRAY_TYPE;
                   gnu_arr_type = TREE_TYPE (gnu_arr_type), index++)
                {
                  tree eltype = TREE_TYPE (gnu_arr_type);
                  char stride_name[32];

                  sprintf (stride_name, "ST%d", index);
                  TYPE_SIZE (gnu_arr_type)
                    = elaborate_expression_1 (TYPE_SIZE (gnu_arr_type),
                                              gnat_entity, stride_name,
                                              definition, false);

                  /* ??? 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.  */
                  sprintf (stride_name, "ST%d_A_UNIT", index);
                  TYPE_SIZE_UNIT (gnu_arr_type)
                    = elaborate_expression_2 (TYPE_SIZE_UNIT (gnu_arr_type),
                                              gnat_entity, stride_name,
                                              definition, false,
                                              TYPE_ALIGN (eltype));

                  /* ??? 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 for debugging purposes, do it now and make the record
             type a parallel type.  This is not needed for a packed array
             since the bounds are conveyed by the original array type.  */
          if (need_index_type_struct
              && debug_info_p
              && !Is_Packed_Array_Impl_Type (gnat_entity))
            {
              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 = ndim - 1; index >= 0; index--)
                {
                  tree gnu_index = TYPE_INDEX_TYPE (gnu_index_types[index]);
                  tree gnu_index_name = TYPE_IDENTIFIER (gnu_index);

                  /* Make sure to reference the types themselves, and not just
                     their names, as the debugger may fall back on them.  */
                  gnu_field = create_field_decl (gnu_index_name, gnu_index,
                                                 gnu_bound_rec, NULL_TREE,
                                                 NULL_TREE, 0, 0);
                  DECL_CHAIN (gnu_field) = gnu_field_list;
                  gnu_field_list = gnu_field;
                }

              finish_record_type (gnu_bound_rec, gnu_field_list, 0, true);
              add_parallel_type (gnu_type, gnu_bound_rec);
            }

          /* If this is a packed array type, make the original array type a
             parallel/debug type.  Otherwise, if such GNAT encodings are
             required, do it for the base array type if it isn't artificial to
             make sure it is kept in the debug info.  */
          if (debug_info_p)
            {
              if (Is_Packed_Array_Impl_Type (gnat_entity))
                associate_original_type_to_packed_array (gnu_type,
                                                         gnat_entity);
              else
                {
                  tree gnu_base_decl
                    = gnat_to_gnu_entity (Etype (gnat_entity), NULL_TREE,
                                          false);
                  if (!DECL_ARTIFICIAL (gnu_base_decl)
                      && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL)
                    add_parallel_type (gnu_type,
                                       TREE_TYPE (TREE_TYPE (gnu_base_decl)));
                }
            }

          TYPE_PACKED_ARRAY_TYPE_P (gnu_type)
            = (Is_Packed_Array_Impl_Type (gnat_entity)
               && Is_Bit_Packed_Array (Original_Array_Type (gnat_entity)));

        /* Tag top-level ARRAY_TYPE nodes for packed arrays and their
           implementation types as such so that the debug information back-end
           can output the appropriate description for them.  */
          TYPE_PACKED (gnu_type)
            = (Is_Packed (gnat_entity)
               || Is_Packed_Array_Impl_Type (gnat_entity));

          /* If the size is self-referential and the maximum size doesn't
             overflow, use it.  */
          if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type))
              && gnu_max_size
              && !(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)))
            {
              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_Impl_Type (gnat_entity)))
            {
              Entity_Id gnat_index;
              tree gnu_inner;

              /* First finish the type we had been making so that we output
                 debugging information for it.  */
              process_attributes (&gnu_type, &attr_list, false, gnat_entity);
              if (Treat_As_Volatile (gnat_entity))
                {
                  const int quals
                    = TYPE_QUAL_VOLATILE
                      | (Is_Atomic_Or_VFA (gnat_entity) ? TYPE_QUAL_ATOMIC : 0);
                  gnu_type = change_qualified_type (gnu_type, quals);
                }
              /* Make it artificial only if the base type was artificial too.
                 That's sort of "morally" true and will make it possible for
                 the debugger to look it up by name in DWARF, which is needed
                 in order to decode the packed array type.  */
              gnu_decl
                = create_type_decl (gnu_entity_name, gnu_type,
                                    !Comes_From_Source (Etype (gnat_entity))
                                    && artificial_p, 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_Impl_Type (gnat_entity),
                                      NULL_TREE, false);
              this_made_decl = true;
              gnu_type = TREE_TYPE (gnu_decl);
              save_gnu_tree (gnat_entity, NULL_TREE, false);
              save_gnu_tree (gnat_entity, gnu_decl, false);
              saved = true;

              gnu_inner = gnu_type;
              while (TREE_CODE (gnu_inner) == RECORD_TYPE
                     && (TYPE_JUSTIFIED_MODULAR_P (gnu_inner)
                         || TYPE_PADDING_P (gnu_inner)))
                gnu_inner = TREE_TYPE (TYPE_FIELDS (gnu_inner));

              /* We need to attach the index type to the type we just made so
                 that the actual bounds can later be put into a template.  */
              if ((TREE_CODE (gnu_inner) == ARRAY_TYPE
                   && !TYPE_ACTUAL_BOUNDS (gnu_inner))
                  || (TREE_CODE (gnu_inner) == INTEGER_TYPE
                      && !TYPE_HAS_ACTUAL_BOUNDS_P (gnu_inner)))
                {
                  if (TREE_CODE (gnu_inner) == INTEGER_TYPE)
                    {
                      /* The TYPE_ACTUAL_BOUNDS field is overloaded with the
                         TYPE_MODULUS for modular types so we make an extra
                         subtype if necessary.  */
                      if (TYPE_MODULAR_P (gnu_inner))
                        {
                          tree gnu_subtype
                            = make_unsigned_type (TYPE_PRECISION (gnu_inner));
                          TREE_TYPE (gnu_subtype) = gnu_inner;
                          TYPE_EXTRA_SUBTYPE_P (gnu_subtype) = 1;
                          SET_TYPE_RM_MIN_VALUE (gnu_subtype,
                                                 TYPE_MIN_VALUE (gnu_inner));
                          SET_TYPE_RM_MAX_VALUE (gnu_subtype,
                                                 TYPE_MAX_VALUE (gnu_inner));
                          gnu_inner = gnu_subtype;
                        }

                      TYPE_HAS_ACTUAL_BOUNDS_P (gnu_inner) = 1;

                      /* Check for other cases of overloading.  */
                      gcc_checking_assert (!TYPE_ACTUAL_BOUNDS (gnu_inner));
                    }

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

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

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

    case E_String_Literal_Subtype:
      /* Create the type for a string literal.  */
      {
        Entity_Id gnat_full_type
          = (Is_Private_Type (Etype (gnat_entity))
             && 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)));
        tree gnu_length
          = UI_To_gnu (String_Literal_Length (gnat_entity),
                       gnu_string_index_type);
        tree gnu_upper_bound
          = build_binary_op (PLUS_EXPR, gnu_string_index_type,
                             gnu_lower_bound,
                             int_const_binop (MINUS_EXPR, gnu_length,
                                              convert (gnu_string_index_type,
                                                       integer_one_node)));
        tree gnu_index_type
          = create_index_type (convert (sizetype, gnu_lower_bound),
                               convert (sizetype, gnu_upper_bound),
                               create_range_type (gnu_string_index_type,
                                                  gnu_lower_bound,
                                                  gnu_upper_bound),
                               gnat_entity);

        gnu_type
          = build_nonshared_array_type (gnat_to_gnu_type
                                        (Component_Type (gnat_entity)),
                                        gnu_index_type);
        if (array_type_has_nonaliased_component (gnu_type, gnat_entity))
          set_nonaliased_component_on_array_type (gnu_type);
        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);
        Node_Id gnat_constr;
        Entity_Id gnat_field, gnat_parent_type;
        tree gnu_field, gnu_field_list = NULL_TREE;
        tree gnu_get_parent;
        /* Set PACKED in keeping with gnat_to_gnu_field.  */
        const int packed
          = Is_Packed (gnat_entity)
            ? 1
            : Component_Alignment (gnat_entity) == Calign_Storage_Unit
              ? -1
              : 0;
        const bool has_align = Known_Alignment (gnat_entity);
        const bool has_discr = Has_Discriminants (gnat_entity);
        const bool has_rep = Has_Specified_Layout (gnat_entity);
        const bool is_extension
          = (Is_Tagged_Type (gnat_entity)
             && Nkind (record_definition) == N_Derived_Type_Definition);
        const bool is_unchecked_union = Is_Unchecked_Union (gnat_entity);
        bool all_rep = has_rep;

        /* See if all fields have a rep clause.  Stop when we find one
           that doesn't.  */
        if (all_rep)
          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)
                && No (Component_Clause (gnat_field)))
              {
                all_rep = false;
                break;
              }

        /* 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_name;
        TYPE_PACKED (gnu_type) = (packed != 0) || has_align || has_rep;
        TYPE_REVERSE_STORAGE_ORDER (gnu_type)
          = Reverse_Storage_Order (gnat_entity);
        process_attributes (&gnu_type, &attr_list, true, gnat_entity);

        if (!definition)
          {
            defer_incomplete_level++;
            this_deferred = true;
          }

        /* If both a size and rep clause were specified, put the size on
           the record type now so that it can get the proper layout.  */
        if (has_rep && Known_RM_Size (gnat_entity))
          TYPE_SIZE (gnu_type)
            = UI_To_gnu (RM_Size (gnat_entity), bitsizetype);

        /* Always set the alignment on the record type here so that it can
           get the proper layout.  */
        if (has_align)
          SET_TYPE_ALIGN (gnu_type,
                          validate_alignment (Alignment (gnat_entity),
                                              gnat_entity, 0));
        else
          {
            SET_TYPE_ALIGN (gnu_type, 0);

            /* 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.  */
            if (Strict_Alignment (gnat_entity) && Known_RM_Size (gnat_entity))
              {
                unsigned int max_size = UI_To_Int (RM_Size (gnat_entity));
                unsigned int max_align = max_size & -max_size;
                if (max_align < BIGGEST_ALIGNMENT)
                  TYPE_MAX_ALIGN (gnu_type) = max_align;
              }
          }

        /* 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_dummy_parent_type = make_node (RECORD_TYPE);
            tree gnu_parent;
            int parent_packed = 0;

            /* A major complexity here is that the parent subtype will
               reference our discriminants in its Stored_Constraint list.
               But those must reference the parent component of this record
               which is precisely 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, gnu_dummy_parent_type,
                                     build0 (PLACEHOLDER_EXPR, gnu_type),
                                     build_decl (input_location,
                                                 FIELD_DECL, NULL_TREE,
                                                 gnu_dummy_parent_type),
                                     NULL_TREE);

            if (has_discr)
              for (gnat_field = First_Stored_Discriminant (gnat_entity);
                   Present (gnat_field);
                   gnat_field = Next_Stored_Discriminant (gnat_field))
                if (Present (Corresponding_Discriminant (gnat_field)))
                  {
                    tree gnu_field
                      = gnat_to_gnu_field_decl (Corresponding_Discriminant
                                                (gnat_field));
                    save_gnu_tree
                      (gnat_field,
                       build3 (COMPONENT_REF, TREE_TYPE (gnu_field),
                               gnu_get_parent, gnu_field, NULL_TREE),
                       true);
                  }

            /* Then we build the parent subtype.  If it has discriminants but
               the type itself has unknown discriminants, this means that it
               doesn't contain information about how the discriminants are
               derived from those of the ancestor type, so it cannot be used
               directly.  Instead it is built by cloning the parent subtype
               of the underlying record view of the type, for which the above
               derivation of discriminants has been made explicit.  */
            if (Has_Discriminants (gnat_parent)
                && Has_Unknown_Discriminants (gnat_entity))
              {
                Entity_Id gnat_uview = Underlying_Record_View (gnat_entity);

                /* If we are defining the type, the underlying record
                   view must already have been elaborated at this point.
                   Otherwise do it now as its parent subtype cannot be
                   technically elaborated on its own.  */
                if (definition)
                  gcc_assert (present_gnu_tree (gnat_uview));
                else
                  gnat_to_gnu_entity (gnat_uview, NULL_TREE, false);

                gnu_parent = gnat_to_gnu_type (Parent_Subtype (gnat_uview));

                /* Substitute the "get to the parent" of the type for that
                   of its underlying record view in the cloned type.  */
                for (gnat_field = First_Stored_Discriminant (gnat_uview);
                     Present (gnat_field);
                     gnat_field = Next_Stored_Discriminant (gnat_field))
                  if (Present (Corresponding_Discriminant (gnat_field)))
                    {
                      tree gnu_field = gnat_to_gnu_field_decl (gnat_field);
                      tree gnu_ref
                        = build3 (COMPONENT_REF, TREE_TYPE (gnu_field),
                                  gnu_get_parent, gnu_field, NULL_TREE);
                      gnu_parent
                        = substitute_in_type (gnu_parent, gnu_field, gnu_ref);
                    }
              }
            else
              gnu_parent = gnat_to_gnu_type (gnat_parent);

            /* The parent field needs strict alignment so, if it is to
               be created with a component clause below, then we need
               to apply the same adjustment as in gnat_to_gnu_field.  */
            if (has_rep && TYPE_ALIGN (gnu_type) < TYPE_ALIGN (gnu_parent))
              {
                /* ??? For historical reasons, we do it on strict-alignment
                   platforms only, where it is really required.  This means
                   that a confirming representation clause will change the
                   behavior of the compiler on the other platforms.  */
                if (STRICT_ALIGNMENT)
                  SET_TYPE_ALIGN (gnu_type, TYPE_ALIGN (gnu_parent));
                else
                  parent_packed
                    = adjust_packed (gnu_parent, gnu_type, parent_packed);
              }

            /* 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_discr)
              {
                /* The actual parent subtype is the full view.  */
                if (Is_Private_Type (gnat_parent))
                  {
                    if (Present (Full_View (gnat_parent)))
                      gnat_parent = Full_View (gnat_parent);
                    else
                      gnat_parent = Underlying_Full_View (gnat_parent);
                  }

                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;
                      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
              = create_field_decl (parent_name_id,
                                   gnu_parent, gnu_type,
                                   has_rep
                                   ? TYPE_SIZE (gnu_parent) : NULL_TREE,
                                   has_rep
                                   ? bitsize_zero_node : NULL_TREE,
                                   parent_packed, 1);
            DECL_INTERNAL_P (gnu_field) = 1;
            TREE_OPERAND (gnu_get_parent, 1) = gnu_field;
            TYPE_FIELDS (gnu_type) = gnu_field;
          }

        /* Make the fields for the discriminants and put them into the record
           unless it's an Unchecked_Union.  */
        if (has_discr)
          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 handled it above.  */
              if (is_extension
                  && Present (Corresponding_Discriminant (gnat_field)))
                continue;

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

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

              if (!is_unchecked_union)
                {
                  DECL_CHAIN (gnu_field) = gnu_field_list;
                  gnu_field_list = gnu_field;
                }
            }

        /* If we have a derived untagged type that renames discriminants in
           the parent type, the (stored) discriminants are just a copy of the
           discriminants of the parent type.  This means that any constraints
           added by the renaming in the derivation are disregarded as far as
           the layout of the derived type is concerned.  To rescue them, we
           change the type of the (stored) discriminants to a subtype with
           the bounds of the type of the visible discriminants.  */
        if (has_discr
            && !is_extension
            && Stored_Constraint (gnat_entity) != No_Elist)
          for (gnat_constr = First_Elmt (Stored_Constraint (gnat_entity));
               gnat_constr != No_Elmt;
               gnat_constr = Next_Elmt (gnat_constr))
            if (Nkind (Node (gnat_constr)) == N_Identifier
                /* Ignore access discriminants.  */
                && !Is_Access_Type (Etype (Node (gnat_constr)))
                && Ekind (Entity (Node (gnat_constr))) == E_Discriminant)
              {
                Entity_Id gnat_discr = Entity (Node (gnat_constr));
                tree gnu_discr_type = gnat_to_gnu_type (Etype (gnat_discr));
                tree gnu_ref
                  = gnat_to_gnu_entity (Original_Record_Component (gnat_discr),
                                        NULL_TREE, false);

                /* GNU_REF must be an expression using a PLACEHOLDER_EXPR built
                   just above for one of the stored discriminants.  */
                gcc_assert (TREE_TYPE (TREE_OPERAND (gnu_ref, 0)) == gnu_type);

                if (gnu_discr_type != TREE_TYPE (gnu_ref))
                  {
                    const unsigned prec = TYPE_PRECISION (TREE_TYPE (gnu_ref));
                    tree gnu_subtype
                      = TYPE_UNSIGNED (TREE_TYPE (gnu_ref))
                        ? make_unsigned_type (prec) : make_signed_type (prec);
                    TREE_TYPE (gnu_subtype) = TREE_TYPE (gnu_ref);
                    TYPE_EXTRA_SUBTYPE_P (gnu_subtype) = 1;
                    SET_TYPE_RM_MIN_VALUE (gnu_subtype,
                                           TYPE_MIN_VALUE (gnu_discr_type));
                    SET_TYPE_RM_MAX_VALUE (gnu_subtype,
                                           TYPE_MAX_VALUE (gnu_discr_type));
                    TREE_TYPE (gnu_ref)
                      = TREE_TYPE (TREE_OPERAND (gnu_ref, 1)) = gnu_subtype;
                  }
              }

        /* If this is a derived type with discriminants and these discriminants
           affect the initial shape it has inherited, factor them in.  But for
           an Unchecked_Union (it must be an Itype), just process the type.  */
        if (has_discr
            && !is_extension
            && !Has_Record_Rep_Clause (gnat_entity)
            && Stored_Constraint (gnat_entity) != No_Elist
            && (gnat_parent_type = Underlying_Type (Etype (gnat_entity)))
            && Is_Record_Type (gnat_parent_type)
            && !Is_Unchecked_Union (gnat_parent_type))
          {
            tree gnu_parent_type
              = TYPE_MAIN_VARIANT (gnat_to_gnu_type (gnat_parent_type));

            if (TYPE_IS_PADDING_P (gnu_parent_type))
              gnu_parent_type = TREE_TYPE (TYPE_FIELDS (gnu_parent_type));

            vec<subst_pair> gnu_subst_list
              = build_subst_list (gnat_entity, gnat_parent_type, definition);

            /* Set the layout of the type to match that of the parent type,
               doing required substitutions.  */
            copy_and_substitute_in_layout (gnat_entity, gnat_parent_type,
                                           gnu_type, gnu_parent_type,
                                           gnu_subst_list, debug_info_p);
          }
        else
          {
            /* Add the fields into the record type and finish it up.  */
            components_to_record (Component_List (record_definition),
                                  gnat_entity, gnu_field_list, gnu_type,
                                  packed, definition, false, all_rep,
                                  is_unchecked_union, artificial_p,
                                  debug_info_p, false,
                                  all_rep ? NULL_TREE : bitsize_zero_node,
                                  NULL);

            /* If there are 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, false);
          }

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

        /* If this is a record type associated with an exception definition,
           equate its fields to those of the standard exception type.  This
           will make it possible to convert between them.  */
        if (gnu_entity_name == exception_data_name_id)
          {
            tree gnu_std_field;
            for (gnu_field = TYPE_FIELDS (gnu_type),
                 gnu_std_field = TYPE_FIELDS (except_type_node);
                 gnu_field;
                 gnu_field = DECL_CHAIN (gnu_field),
                 gnu_std_field = DECL_CHAIN (gnu_std_field))
              SET_DECL_ORIGINAL_FIELD_TO_FIELD (gnu_field, gnu_std_field);
            gcc_assert (!gnu_std_field);
          }
      }
      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, false);
          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, false);
          maybe_present = true;
          break;
        }

      /* 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 the position computed by transforming
         every discriminant reference according to the constraints.  We don't
         see any difference between private and non-private 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);

          if (!definition)
            {
              defer_incomplete_level++;
              this_deferred = true;
            }

          tree gnu_base_type
            = TYPE_MAIN_VARIANT (gnat_to_gnu_type (gnat_base_type));

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

          /* If this is a record subtype associated with a dispatch table,
             strip the suffix.  This is necessary to make sure 2 different
             subtypes associated with the imported and exported views of a
             dispatch table are properly merged in LTO mode.  */
          if (Is_Dispatch_Table_Entity (gnat_entity))
            {
              char *p;
              Get_Encoded_Name (gnat_entity);
              p = strchr (Name_Buffer, '_');
              gcc_assert (p);
              strcpy (p+2, "dtS");
              gnu_entity_name = get_identifier (Name_Buffer);
            }

          /* When the subtype has discriminants and these discriminants affect
             the initial shape it has inherited, factor them in.  But for an
             Unchecked_Union (it must be an Itype), just return the type.  */
          if (Has_Discriminants (gnat_entity)
              && Stored_Constraint (gnat_entity) != No_Elist
              && !Is_For_Access_Subtype (gnat_entity)
              && Is_Record_Type (gnat_base_type)
              && !Is_Unchecked_Union (gnat_base_type))
            {
              vec<subst_pair> gnu_subst_list
                = build_subst_list (gnat_entity, gnat_base_type, definition);
              tree gnu_unpad_base_type;

              gnu_type = make_node (RECORD_TYPE);
              TYPE_NAME (gnu_type) = gnu_entity_name;
              if (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
                SET_TYPE_DEBUG_TYPE (gnu_type, gnu_base_type);
              TYPE_PACKED (gnu_type) = TYPE_PACKED (gnu_base_type);
              TYPE_REVERSE_STORAGE_ORDER (gnu_type)
                = Reverse_Storage_Order (gnat_entity);
              process_attributes (&gnu_type, &attr_list, true, gnat_entity);

              /* Set the size, alignment and alias set of the type to match
                 those of the base type, doing required substitutions.  */
              copy_and_substitute_in_size (gnu_type, gnu_base_type,
                                           gnu_subst_list);

              if (TYPE_IS_PADDING_P (gnu_base_type))
                gnu_unpad_base_type = TREE_TYPE (TYPE_FIELDS (gnu_base_type));
              else
                gnu_unpad_base_type = gnu_base_type;

              /* Set the layout of the type to match that of the base type,
                 doing required substitutions.  We will output debug info
                 manually below so pass false as last argument.  */
              copy_and_substitute_in_layout (gnat_entity, gnat_base_type,
                                             gnu_type, gnu_unpad_base_type,
                                             gnu_subst_list, false);

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

              /* If debugging information is being written for the type and if
                 we are asked to output such encodings, write a record that
                 shows what we are a subtype of and also make a variable that
                 indicates our size, if still variable.  */
              if (gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL)
                {
                  tree gnu_subtype_marker = make_node (RECORD_TYPE);
                  tree gnu_unpad_base_name
                    = TYPE_IDENTIFIER (gnu_unpad_base_type);
                  tree gnu_size_unit = TYPE_SIZE_UNIT (gnu_type);

                  TYPE_NAME (gnu_subtype_marker)
                    = create_concat_name (gnat_entity, "XVS");
                  finish_record_type (gnu_subtype_marker,
                                      create_field_decl (gnu_unpad_base_name,
                                                         build_reference_type
                                                         (gnu_unpad_base_type),
                                                         gnu_subtype_marker,
                                                         NULL_TREE, NULL_TREE,
                                                         0, 0),
                                      0, true);

                  add_parallel_type (gnu_type, gnu_subtype_marker);

                  if (definition
                      && TREE_CODE (gnu_size_unit) != INTEGER_CST
                      && !CONTAINS_PLACEHOLDER_P (gnu_size_unit))
                    TYPE_SIZE_UNIT (gnu_subtype_marker)
                      = create_var_decl (create_concat_name (gnat_entity,
                                                             "XVZ"),
                                         NULL_TREE, sizetype, gnu_size_unit,
                                         false, false, false, false, false,
                                         true, debug_info_p,
                                         NULL, gnat_entity);
                }
            }

          /* Otherwise, go down all the components in the new type and make
             them equivalent to those in the base type.  */
          else
            {
              gnu_type = gnu_base_type;

              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:
    case E_Anonymous_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_Allocator_Type:
    case E_Access_Type:
    case E_Access_Attribute_Type:
    case E_Anonymous_Access_Type:
    case E_General_Access_Type:
      {
        /* The designated type and its equivalent type for gigi.  */
        Entity_Id gnat_desig_type = Directly_Designated_Type (gnat_entity);
        Entity_Id gnat_desig_equiv = Gigi_Equivalent_Type (gnat_desig_type);
        /* Whether it comes from a limited with.  */
        const bool is_from_limited_with
          = (Is_Incomplete_Type (gnat_desig_equiv)
             && From_Limited_With (gnat_desig_equiv));
        /* Whether it is a completed Taft Amendment type.  Such a type is to
           be treated as coming from a limited with clause if it is not in
           the main unit, i.e. we break potential circularities here in case
           the body of an external unit is loaded for inter-unit inlining.  */
        const bool is_completed_taft_type
          = (Is_Incomplete_Type (gnat_desig_equiv)
             && Has_Completion_In_Body (gnat_desig_equiv)
             && Present (Full_View (gnat_desig_equiv)));
        /* The "full view" of the designated type.  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)
             : (Is_Incomplete_Or_Private_Type (gnat_desig_equiv)
                ? Full_View (gnat_desig_equiv) : Empty));
        Entity_Id gnat_desig_full_direct
          = ((is_from_limited_with
              && Present (gnat_desig_full_direct_first)
              && Is_Private_Type (gnat_desig_full_direct_first))
             ? Full_View (gnat_desig_full_direct_first)
             : gnat_desig_full_direct_first);
        Entity_Id gnat_desig_full
          = Gigi_Equivalent_Type (gnat_desig_full_direct);
        /* The type actually used to represent the designated type, either
           gnat_desig_full or gnat_desig_equiv.  */
        Entity_Id gnat_desig_rep;
        /* We want to know if we'll be seeing the freeze node for any
           incomplete type we may be pointing to.  */
        const 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 made_dummy = false;
        /* The mode to be used for the pointer type.  */
        scalar_int_mode p_mode;
        /* The GCC type used for the designated type.  */
        tree gnu_desig_type = NULL_TREE;

        if (!int_mode_for_size (esize, 0).exists (&p_mode)
            || !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);

        /* Set the type that's the representation of the designated type.  */
        gnat_desig_rep
          = Present (gnat_desig_full) ? gnat_desig_full : gnat_desig_equiv;

        /* If we already know what the full type is, use it.  */
        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, an array or an access, make a dummy type
           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)
                  && (Is_Record_Type (gnat_desig_full)
                      || Is_Array_Type (gnat_desig_full)
                      || Is_Access_Type (gnat_desig_full)))
                 /* Likewise if this is a reference to a record, an array or a
                    subprogram type and we are to defer elaborating incomplete
                    types.  We do this because this access type may be the full
                    view of a private type.  */
                 || ((!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)
                         || Ekind (gnat_desig_rep) == E_Subprogram_Type))
                 /* 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 finally processed.  In both cases,
                    the pointer eventually created below will be automatically
                    adjusted when the freeze node is processed.  */
                 || (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 we use the void pointer type.  */
        else if (type_annotate_only && No (gnat_desig_equiv))
          gnu_type = ptr_type_node;

        /* If the ultimately designated type is an incomplete type with no full
           view, we use the void pointer type in LTO mode to avoid emitting a
           dummy type in the GIMPLE IR.  We cannot do that in regular mode as
           the name of the dummy type in used by GDB for a global lookup.  */
        else if (Ekind (gnat_desig_rep) == E_Incomplete_Type
                 && No (Full_View (gnat_desig_rep))
                 && flag_generate_lto)
          gnu_type = ptr_type_node;

        /* Finally, handle the default case where we can just elaborate our
           designated type.  */
        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;
          }

        /* Access-to-unconstrained-array types need a special treatment.  */
        if (Is_Array_Type (gnat_desig_rep) && !Is_Constrained (gnat_desig_rep))
          {
            /* If the processing above got something that has a pointer, then
               we are done.  This could have happened either because the type
               was elaborated or because somebody else executed the code.  */
            if (!TYPE_POINTER_TO (gnu_desig_type))
              build_dummy_unc_pointer_types (gnat_desig_equiv, gnu_desig_type);

            gnu_type = TYPE_POINTER_TO (gnu_desig_type);
          }

        /* If we haven't done it yet, build the pointer type the usual way.  */
        else if (!gnu_type)
          {
            /* Modify the designated type if we are pointing only to constant
               objects, but don't do it for a dummy type.  */
            if (Is_Access_Constant (gnat_entity)
                && !TYPE_IS_DUMMY_P (gnu_desig_type))
              gnu_desig_type
                = change_qualified_type (gnu_desig_type, TYPE_QUAL_CONST);

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

        /* If the designated type is not declared in the main unit and we made
           a dummy node for it, save our definition, elaborate the actual type
           and replace the dummy type we made with the actual one.  But if we
           are to defer actually looking up the actual type, make an entry in
           the deferred list instead.  If this is from a limited with, we may
           have to defer until the end of the current unit.  */
        if (!in_main_unit && made_dummy)
          {
            if (TYPE_IS_FAT_POINTER_P (gnu_type) && esize == POINTER_SIZE)
              gnu_type
                = build_pointer_type (TYPE_OBJECT_RECORD_TYPE (gnu_desig_type));

            process_attributes (&gnu_type, &attr_list, false, gnat_entity);
            gnu_decl = create_type_decl (gnu_entity_name, gnu_type,
                                         artificial_p, 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
                && !is_completed_taft_type)
              {
                update_pointer_to (TYPE_MAIN_VARIANT (gnu_desig_type),
                                   gnat_to_gnu_type (gnat_desig_equiv));
              }
            else
              {
                struct incomplete *p = XNEW (struct incomplete);
                struct incomplete **head
                  = (is_from_limited_with || is_completed_taft_type
                     ? &defer_limited_with_list : &defer_incomplete_list);

                p->old_type = gnu_desig_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 we are just annotating types and have no equivalent record type,
         just use the void pointer type.  */
      if (type_annotate_only && gnat_equiv_type == gnat_entity)
        gnu_type = ptr_type_node;

      /* The run-time representation is the equivalent type.  */
      else
        {
          gnu_type = gnat_to_gnu_type (gnat_equiv_type);
          maybe_present = true;
        }

      /* The designated subtype must be elaborated as well, if it does
         not have its own freeze node.  */
      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, false);

      break;

    case E_Access_Subtype:
      /* We treat this as identical to its base type; any constraint is
         meaningful only to the front-end.  */
      gnu_decl = gnat_to_gnu_entity (Etype (gnat_entity), NULL_TREE, false);
      saved = true;

      /* The designated subtype must be elaborated as well, if it does
         not have its own freeze node.  But designated subtypes created
         for constrained components of records with discriminants are
         not frozen by the front-end and not elaborated here, because
         their use may appear before the base type is frozen and it is
         not clear that they are needed in gigi.  With the current model,
         there is no correct place where they could be elaborated.  */
      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 to defer elaborating incomplete types, make a dummy
             type node and elaborate it later.  */
          if (defer_incomplete_level != 0)
            {
              struct incomplete *p = XNEW (struct incomplete);

              p->old_type
                = make_dummy_type (Directly_Designated_Type (gnat_entity));
              p->full_type = Directly_Designated_Type (gnat_entity);
              p->next = defer_incomplete_list;
              defer_incomplete_list = p;
            }
          else if (!Is_Incomplete_Or_Private_Type
                      (Base_Type (Directly_Designated_Type (gnat_entity))))
            gnat_to_gnu_entity (Directly_Designated_Type (gnat_entity),
                                NULL_TREE, false);
        }
      break;

    /* Subprogram Entities

       The following access functions are defined for subprograms:

                Etype           Return type or Standard_Void_Type.
                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.

       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:
      {
        tree gnu_ext_name
          = gnu_ext_name_for_subprog (gnat_entity, gnu_entity_name);
        enum inline_status_t inline_status
          = Has_Pragma_No_Inline (gnat_entity)
            ? is_suppressed
            : Has_Pragma_Inline_Always (gnat_entity)
              ? is_required
              : (Is_Inlined (gnat_entity) ? is_enabled : is_disabled);
        bool public_flag = Is_Public (gnat_entity) || imported_p;
        /* Subprograms marked both Intrinsic and Always_Inline need not
           have a body of their own.  */
        bool extern_flag
          = ((Is_Public (gnat_entity) && !definition)
             || imported_p
             || (Convention (gnat_entity) == Convention_Intrinsic
                 && Has_Pragma_Inline_Always (gnat_entity)));
        tree gnu_param_list;

        /* A parameter may refer to this type, so defer completion of any
           incomplete types.  */
        if (kind == E_Subprogram_Type && !definition)
          {
            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)))
          {
            const Entity_Id gnat_renamed = Renamed_Object (gnat_entity);

            if (Ekind (Alias (gnat_entity)) == E_Enumeration_Literal)
              gnat_to_gnu_entity (Etype (Alias (gnat_entity)), NULL_TREE,
                                  false);

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

            /* 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, false);

            /* Materialize renamed subprograms in the debugging information
               when the renamed object is compile time known.  We can consider
               such renamings as imported declarations.

               Because the parameters in generics instantiation are generally
               materialized as renamings, we ofter end up having both the
               renamed subprogram and the renaming in the same context and with
               the same name: in this case, renaming is both useless debug-wise
               and potentially harmful as name resolution in the debugger could
               return twice the same entity!  So avoid this case.  */
            if (debug_info_p && !artificial_p
                && !(get_debug_scope (gnat_entity, NULL)
                       == get_debug_scope (gnat_renamed, NULL)
                     && Name_Equals (Chars (gnat_entity),
                                     Chars (gnat_renamed)))
                && Present (gnat_renamed)
                && (Ekind (gnat_renamed) == E_Function
                    || Ekind (gnat_renamed) == E_Procedure)
                && gnu_decl
                && TREE_CODE (gnu_decl) == FUNCTION_DECL)
              {
                tree decl = build_decl (input_location, IMPORTED_DECL,
                                        gnu_entity_name, void_type_node);
                IMPORTED_DECL_ASSOCIATED_DECL (decl) = gnu_decl;
                gnat_pushdecl (decl, gnat_entity);
              }

            break;
          }

        /* Get the GCC tree for the (underlying) subprogram type.  If the
           entity is an actual subprogram, also get the parameter list.  */
        gnu_type
          = gnat_to_gnu_subprog_type (gnat_entity, definition, debug_info_p,
                                      &gnu_param_list);
        if (DECL_P (gnu_type))
          {
            gnu_decl = gnu_type;
            gnu_type = TREE_TYPE (gnu_decl);
            break;
          }

        /* Deal with platform-specific calling conventions.  */
        if (Has_Stdcall_Convention (gnat_entity))
          prepend_one_attribute
            (&attr_list, ATTR_MACHINE_ATTRIBUTE,
             get_identifier ("stdcall"), NULL_TREE,
             gnat_entity);
        else if (Has_Thiscall_Convention (gnat_entity))
          prepend_one_attribute
            (&attr_list, ATTR_MACHINE_ATTRIBUTE,
             get_identifier ("thiscall"), NULL_TREE,
             gnat_entity);

        /* If we should request stack realignment for a foreign convention
           subprogram, do so.  Note that this applies to task entry points
           in particular.  */
        if (FOREIGN_FORCE_REALIGN_STACK
            && Has_Foreign_Convention (gnat_entity))
          prepend_one_attribute
            (&attr_list, ATTR_MACHINE_ATTRIBUTE,
             get_identifier ("force_align_arg_pointer"), NULL_TREE,
             gnat_entity);

        /* Deal with a pragma Linker_Section on a subprogram.  */
        if ((kind == E_Function || kind == E_Procedure)
            && Present (Linker_Section_Pragma (gnat_entity)))
          prepend_one_attribute_pragma (&attr_list,
                                        Linker_Section_Pragma (gnat_entity));

        /* 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 RM 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_name, gnu_ext_name, gnu_type,
                                 gnu_address, false, Is_Public (gnat_entity),
                                 extern_flag, false, false, artificial_p,
                                 debug_info_p, NULL, gnat_entity);
            DECL_BY_REF_P (gnu_decl) = 1;
          }

        /* If this is a mere subprogram type, just create the declaration.  */
        else if (kind == E_Subprogram_Type)
          {
            process_attributes (&gnu_type, &attr_list, false, gnat_entity);

            gnu_decl
              = create_type_decl (gnu_entity_name, gnu_type, artificial_p,
                                  debug_info_p, gnat_entity);
          }

        /* Otherwise create the subprogram declaration with the external name,
           the type and the parameter list.  However, if this a reference to
           the allocation routines, reuse the canonical declaration nodes as
           they come with special properties.  */
        else
          {
            if (extern_flag && gnu_ext_name == DECL_NAME (malloc_decl))
              gnu_decl = malloc_decl;
            else if (extern_flag && gnu_ext_name == DECL_NAME (realloc_decl))
              gnu_decl = realloc_decl;
            else
              {
                gnu_decl
                  = create_subprog_decl (gnu_entity_name, gnu_ext_name,
                                         gnu_type, gnu_param_list,
                                         inline_status, public_flag,
                                         extern_flag, artificial_p,
                                         debug_info_p,
                                         definition && imported_p, attr_list,
                                         gnat_entity);

                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:
      {
        const bool is_from_limited_with
          = (IN (kind, Incomplete_Kind) && From_Limited_With (gnat_entity));
        /* 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.  */
        const Entity_Id full_view
          = is_from_limited_with
            ? Non_Limited_View (gnat_entity)
            : Present (Full_View (gnat_entity))
              ? Full_View (gnat_entity)
              : IN (kind, Private_Kind)
                ? Underlying_Full_View (gnat_entity)
                : Empty;

        /* If this is an incomplete type with no full view, it must be a Taft
           Amendment type or an incomplete type coming from a limited context,
           in which cases we return a dummy type.  Otherwise, we 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, false);
                maybe_present = true;
              }
          }

        /* Or else, 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);

        /* Or else, if we are not defining the type or there is no freeze
           node on it, get the type for the full view.  Likewise if this is
           a limited_with'ed type not declared in the main unit, which can
           happen for incomplete formal types instantiated on a type coming
           from a limited_with clause.  */
        else if (!definition
                 || No (Freeze_Node (full_view))
                 || (is_from_limited_with
                     && !In_Extended_Main_Code_Unit (full_view)))
          {
            gnu_decl = gnat_to_gnu_entity (full_view, NULL_TREE, false);
            maybe_present = true;
          }

        /* Otherwise, 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.  */
        else
          {
            gnu_type = make_dummy_type (gnat_entity);
            gnu_decl = TYPE_STUB_DECL (gnu_type);
            if (Has_Completion_In_Body (gnat_entity))
              DECL_TAFT_TYPE_P (gnu_decl) = 1;
            save_gnu_tree (full_view, gnu_decl, false);
          }
      }
      break;

    case E_Class_Wide_Type:
      /* Class-wide types are always transformed into their root type.  */
      gnu_decl = gnat_to_gnu_entity (gnat_equiv_type, NULL_TREE, false);
      maybe_present = true;
      break;

    case E_Protected_Type:
    case E_Protected_Subtype:
    case E_Task_Type:
    case E_Task_Subtype:
      /* If we are just annotating types and have no equivalent record type,
         just return void_type, except for root types that have discriminants
         because the discriminants will very likely be used in the declarative
         part of the associated body so they need to be translated.  */
      if (type_annotate_only && gnat_equiv_type == gnat_entity)
        {
          if (Has_Discriminants (gnat_entity)
              && Root_Type (gnat_entity) == gnat_entity)
            {
              tree gnu_field_list = NULL_TREE;
              Entity_Id gnat_field;

              /* This is a minimal version of the E_Record_Type handling.  */
              gnu_type = make_node (RECORD_TYPE);
              TYPE_NAME (gnu_type) = gnu_entity_name;

              for (gnat_field = First_Stored_Discriminant (gnat_entity);
                   Present (gnat_field);
                   gnat_field = Next_Stored_Discriminant (gnat_field))
                {
                  tree gnu_field
                    = gnat_to_gnu_field (gnat_field, gnu_type, false,
                                         definition, debug_info_p);

                  save_gnu_tree (gnat_field,
                                 build3 (COMPONENT_REF, TREE_TYPE (gnu_field),
                                         build0 (PLACEHOLDER_EXPR, gnu_type),
                                         gnu_field, NULL_TREE),
                                 true);

                  DECL_CHAIN (gnu_field) = gnu_field_list;
                  gnu_field_list = gnu_field;
                }

              finish_record_type (gnu_type, nreverse (gnu_field_list), 0,
                                  false);
            }
          else
            gnu_type = void_type_node;
        }

      /* Concurrent types are always transformed into their record type.  */
      else
        gnu_decl = gnat_to_gnu_entity (gnat_equiv_type, NULL_TREE, false);
      maybe_present = true;
      break;

    case E_Label:
      gnu_decl = create_label_decl (gnu_entity_name, gnat_entity);
      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;

    case E_Abstract_State:
      /* This is a SPARK annotation that only reaches here when compiling in
         ASIS mode.  */
      gcc_assert (type_annotate_only);
      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 (is_type && (!gnu_decl || this_made_decl))
    {
      gcc_assert (!TYPE_IS_DUMMY_P (gnu_type));

      /* Process the attributes, if not already done.  Note that the type is
         already defined so we cannot pass true for IN_PLACE here.  */
      process_attributes (&gnu_type, &attr_list, false, gnat_entity);

      /* Tell the middle-end that objects of tagged types are guaranteed to
         be properly aligned.  This is necessary because conversions to the
         class-wide type are translated into conversions to the root type,
         which can be less aligned than some of its derived types.  */
      if (Is_Tagged_Type (gnat_entity)
          || Is_Class_Wide_Equivalent_Type (gnat_entity))
        TYPE_ALIGN_OK (gnu_type) = 1;

      /* Record whether the type is passed by reference.  */
      if (!VOID_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)
        {
          Uint gnat_size = Known_Esize (gnat_entity)
                           ? Esize (gnat_entity) : RM_Size (gnat_entity);
          gnu_size
            = validate_size (gnat_size, 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 = NULL_TREE;
        }

      /* If the alignment has not already been processed and this is not
         an unconstrained array type, 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 or unions as the type size has
                 already been adjusted to the alignment.  */
              if (gnu_size)
                size = gnu_size;
              else if (RECORD_OR_UNION_TYPE_P (gnu_type)
                       && !TYPE_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 (tree_fits_uhwi_p (size)
                  && align >= tree_to_uhwi (size) * BITS_PER_UNIT)
                post_error_ne ("?suspiciously large alignment specified for&",
                               Expression (Alignment_Clause (gnat_entity)),
                               gnat_entity);
            }
        }
      else if (Is_Atomic_Or_VFA (gnat_entity) && !gnu_size
               && tree_fits_uhwi_p (TYPE_SIZE (gnu_type))
               && integer_pow2p (TYPE_SIZE (gnu_type)))
        align = MIN (BIGGEST_ALIGNMENT,
                     tree_to_uhwi (TYPE_SIZE (gnu_type)));
      else if (Is_Atomic_Or_VFA (gnat_entity) && gnu_size
               && tree_fits_uhwi_p (gnu_size)
               && integer_pow2p (gnu_size))
        align = MIN (BIGGEST_ALIGNMENT, tree_to_uhwi (gnu_size));

      /* 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,
                                   false, !gnu_decl, definition, false);

      if (TYPE_IS_PADDING_P (gnu_type))
        gnu_entity_name = TYPE_IDENTIFIER (gnu_type);

      /* Now set the RM size of the type.  We cannot do it before padding
         because we need to accept arbitrary RM sizes on integral types.  */
      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 (TYPE_SIZE (gnu_type)
          && !TREE_CONSTANT (TYPE_SIZE (gnu_type))
          && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type))
          && global_bindings_p ())
        {
          tree size = TYPE_SIZE (gnu_type);

          TYPE_SIZE (gnu_type)
            = elaborate_expression_1 (size, gnat_entity, "SIZE", definition,
                                      false);

          /* ??? 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)
            = elaborate_expression_2 (TYPE_SIZE_UNIT (gnu_type), gnat_entity,
                                      "SIZE_A_UNIT", definition, false,
                                      TYPE_ALIGN (gnu_type));

          /* ??? gnu_type may come from an existing type so the MULT_EXPR node
             may not be marked by the call to create_type_decl below.  */
          MARK_VISITED (TYPE_SIZE_UNIT (gnu_type));

          if (TREE_CODE (gnu_type) == RECORD_TYPE)
            {
              tree variant_part = get_variant_part (gnu_type);
              tree ada_size = TYPE_ADA_SIZE (gnu_type);

              if (variant_part)
                {
                  tree union_type = TREE_TYPE (variant_part);
                  tree offset = DECL_FIELD_OFFSET (variant_part);

                  /* If the position of the variant part is constant, subtract
                     it from the size of the type of the parent to get the new
                     size.  This manual CSE reduces the data size.  */
                  if (TREE_CODE (offset) == INTEGER_CST)
                    {
                      tree bitpos = DECL_FIELD_BIT_OFFSET (variant_part);
                      TYPE_SIZE (union_type)
                        = size_binop (MINUS_EXPR, TYPE_SIZE (gnu_type),
                                      bit_from_pos (offset, bitpos));
                      TYPE_SIZE_UNIT (union_type)
                        = size_binop (MINUS_EXPR, TYPE_SIZE_UNIT (gnu_type),
                                      byte_from_pos (offset, bitpos));
                    }
                  else
                    {
                      TYPE_SIZE (union_type)
                        = elaborate_expression_1 (TYPE_SIZE (union_type),
                                                  gnat_entity, "VSIZE",
                                                  definition, false);

                      /* ??? 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 (union_type)
                        = elaborate_expression_2 (TYPE_SIZE_UNIT (union_type),
                                                  gnat_entity, "VSIZE_A_UNIT",
                                                  definition, false,
                                                  TYPE_ALIGN (union_type));

                      /* ??? For now, store the offset as a multiple of the
                         alignment in bytes so that we can see the alignment
                         from the tree.  */
                      DECL_FIELD_OFFSET (variant_part)
                        = elaborate_expression_2 (offset, gnat_entity,
                                                  "VOFFSET", definition, false,
                                                  DECL_OFFSET_ALIGN
                                                  (variant_part));
                    }

                  DECL_SIZE (variant_part) = TYPE_SIZE (union_type);
                  DECL_SIZE_UNIT (variant_part) = TYPE_SIZE_UNIT (union_type);
                }

              if (operand_equal_p (ada_size, size, 0))
                ada_size = TYPE_SIZE (gnu_type);
              else
                ada_size
                  = elaborate_expression_1 (ada_size, gnat_entity, "RM_SIZE",
                                            definition, false);
              SET_TYPE_ADA_SIZE (gnu_type, ada_size);
            }
        }

      /* Similarly, if this is a record type or subtype at global level, call
         elaborate_expression_2 on any field position.  Skip any fields that
         we haven't made trees for to avoid problems with class-wide types.  */
      if (IN (kind, Record_Kind) && global_bindings_p ())
        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);

              /* ??? For now, store the offset as a multiple of the alignment
                 in bytes so that we can see the alignment from the tree.  */
              if (!TREE_CONSTANT (DECL_FIELD_OFFSET (gnu_field))
                  && !CONTAINS_PLACEHOLDER_P (DECL_FIELD_OFFSET (gnu_field)))
                {
                  DECL_FIELD_OFFSET (gnu_field)
                    = elaborate_expression_2 (DECL_FIELD_OFFSET (gnu_field),
                                              gnat_temp, "OFFSET", definition,
                                              false,
                                              DECL_OFFSET_ALIGN (gnu_field));

                  /* ??? 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.  */
                  MARK_VISITED (DECL_FIELD_OFFSET (gnu_field));
                }
            }

      if (Is_Atomic_Or_VFA (gnat_entity))
        check_ok_for_atomic_type (gnu_type, gnat_entity, false);

      /* If this is not an unconstrained array type, set some flags.  */
      if (TREE_CODE (gnu_type) != UNCONSTRAINED_ARRAY_TYPE)
        {
          if (Present (Alignment_Clause (gnat_entity)))
            TYPE_USER_ALIGN (gnu_type) = 1;

          if (Universal_Aliasing (gnat_entity) && !TYPE_IS_DUMMY_P (gnu_type))
            TYPE_UNIVERSAL_ALIASING_P (gnu_type) = 1;

          /* If it is passed by reference, force BLKmode to ensure that
             objects of this type will always be put in memory.  */
          if (TYPE_MODE (gnu_type) != BLKmode
              && AGGREGATE_TYPE_P (gnu_type)
              && TYPE_BY_REFERENCE_P (gnu_type))
            SET_TYPE_MODE (gnu_type, BLKmode);
        }

      /* 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

         However, for composite types, conversions between derived types are
         translated into VIEW_CONVERT_EXPRs so a sequence like:

            type Comp1 is new Comp;
            type Comp2 is new Comp;
            procedure Proc (C : Comp1);

            C : Comp2;
            Proc (Comp1 (C));

         is translated into:

            C : Comp2;
            Proc ((Comp1 &) &VIEW_CONVERT_EXPR <Comp1> (C));

         and gimplified into:

            C : Comp2;
            Comp1 *C.0;
            C.0 = (Comp1 *) &C;
            Proc (C.0);

         i.e. generates code involving type punning.  Therefore, Comp1 needs
         to conflict with Comp2 and an alias set copy is required.

         The language rules ensure the parent type is already frozen here.  */
      if (kind != E_Subprogram_Type
          && Is_Derived_Type (gnat_entity)
          && !type_annotate_only)
        {
          Entity_Id gnat_parent_type = Underlying_Type (Etype (gnat_entity));
          /* For constrained packed array subtypes, the implementation type is
             used instead of the nominal type.  */
          if (kind == E_Array_Subtype
              && Is_Constrained (gnat_entity)
              && Present (Packed_Array_Impl_Type (gnat_parent_type)))
            gnat_parent_type = Packed_Array_Impl_Type (gnat_parent_type);
          relate_alias_sets (gnu_type, gnat_to_gnu_type (gnat_parent_type),
                             Is_Composite_Type (gnat_entity)
                             ? ALIAS_SET_COPY : ALIAS_SET_SUPERSET);
        }

      if (Treat_As_Volatile (gnat_entity))
        {
          const int quals
            = TYPE_QUAL_VOLATILE
              | (Is_Atomic_Or_VFA (gnat_entity) ? TYPE_QUAL_ATOMIC : 0);
          gnu_type = change_qualified_type (gnu_type, quals);
        }

      if (!gnu_decl)
        gnu_decl = create_type_decl (gnu_entity_name, gnu_type,
                                     artificial_p, debug_info_p,
                                     gnat_entity);
      else
        {
          TREE_TYPE (gnu_decl) = gnu_type;
          TYPE_STUB_DECL (gnu_type) = gnu_decl;
        }
    }

  /* If we got a type that is not dummy, back-annotate the alignment of the
     type if not already in the tree.  Likewise for the size, if any.  */
  if (is_type && !TYPE_IS_DUMMY_P (TREE_TYPE (gnu_decl)))
    {
      gnu_type = TREE_TYPE (gnu_decl);

      if (Unknown_Alignment (gnat_entity))
        {
          unsigned int double_align, align;
          bool is_capped_double, align_clause;

          /* If the default alignment of "double" or larger scalar types is
             specifically capped and this is not an array with an alignment
             clause on the component type, return the cap.  */
          if ((double_align = double_float_alignment) > 0)
            is_capped_double
              = is_double_float_or_array (gnat_entity, &align_clause);
          else if ((double_align = double_scalar_alignment) > 0)
            is_capped_double
              = is_double_scalar_or_array (gnat_entity, &align_clause);
          else
            is_capped_double = align_clause = false;

          if (is_capped_double && !align_clause)
            align = double_align;
          else
            align = TYPE_ALIGN (gnu_type) / BITS_PER_UNIT;

          Set_Alignment (gnat_entity, UI_From_Int (align));
        }

      if (Unknown_Esize (gnat_entity) && TYPE_SIZE (gnu_type))
        {
          tree gnu_size = TYPE_SIZE (gnu_type);

          /* If the size is self-referential, annotate the maximum value.  */
          if (CONTAINS_PLACEHOLDER_P (gnu_size))
            gnu_size = max_size (gnu_size, true);

          /* If we are just annotating types and the type is tagged, the tag
             and the parent components are not generated by the front-end so
             alignment and sizes must be adjusted if there is no rep clause.  */
          if (type_annotate_only
              && Is_Tagged_Type (gnat_entity)
              && Unknown_RM_Size (gnat_entity)
              && !VOID_TYPE_P (gnu_type)
              && (!TYPE_FIELDS (gnu_type)
                  || integer_zerop (bit_position (TYPE_FIELDS (gnu_type)))))
            {
              tree offset;

              if (Is_Derived_Type (gnat_entity))
                {
                  Entity_Id gnat_parent = Etype (Base_Type (gnat_entity));
                  offset = UI_To_gnu (Esize (gnat_parent), bitsizetype);
                  Set_Alignment (gnat_entity, Alignment (gnat_parent));
                }
              else
                {
                  unsigned int align
                    = MAX (TYPE_ALIGN (gnu_type), POINTER_SIZE) / BITS_PER_UNIT;
                  offset = bitsize_int (POINTER_SIZE);
                  Set_Alignment (gnat_entity, UI_From_Int (align));
                }

              if (TYPE_FIELDS (gnu_type))
                offset
                  = round_up (offset, DECL_ALIGN (TYPE_FIELDS (gnu_type)));

              gnu_size = size_binop (PLUS_EXPR, gnu_size, offset);
              gnu_size = round_up (gnu_size, POINTER_SIZE);
              Uint uint_size = annotate_value (gnu_size);
              Set_RM_Size (gnat_entity, uint_size);
              Set_Esize (gnat_entity, uint_size);
            }

          /* If there is a rep clause, only adjust alignment and Esize.  */
          else if (type_annotate_only && Is_Tagged_Type (gnat_entity))
            {
              unsigned int align
                = MAX (TYPE_ALIGN (gnu_type), POINTER_SIZE) / BITS_PER_UNIT;
              Set_Alignment (gnat_entity, UI_From_Int (align));
              gnu_size = round_up (gnu_size, POINTER_SIZE);
              Set_Esize (gnat_entity, annotate_value (gnu_size));
            }

          /* Otherwise no adjustment is needed.  */
          else
            Set_Esize (gnat_entity, annotate_value (gnu_size));
        }

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

  /* 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);

  /* Now we are sure gnat_entity has a corresponding ..._DECL node,
     eliminate as many deferred computations as possible.  */
  process_deferred_decl_context (false);

  /* If this is an enumeration or floating-point type, we were not able to set
     the bounds since they refer to the type.  These are always static.  */
  if ((kind == E_Enumeration_Type && Present (First_Literal (gnat_entity)))
      || (kind == E_Floating_Point_Type))
    {
      tree gnu_scalar_type = gnu_type;
      tree gnu_low_bound, gnu_high_bound;

      /* If this is a padded type, we need to use the underlying type.  */
      if (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_scalar_type;

      gnu_low_bound = gnat_to_gnu (Type_Low_Bound (gnat_entity));
      gnu_high_bound = gnat_to_gnu (Type_High_Bound (gnat_entity));

      if (kind == E_Enumeration_Type)
        {
          /* Enumeration types have specific RM bounds.  */
          SET_TYPE_RM_MIN_VALUE (gnu_scalar_type, gnu_low_bound);
          SET_TYPE_RM_MAX_VALUE (gnu_scalar_type, gnu_high_bound);
        }
      else
        {
          /* Floating-point types don't have specific RM bounds.  */
          TYPE_GCC_MIN_VALUE (gnu_scalar_type) = gnu_low_bound;
          TYPE_GCC_MAX_VALUE (gnu_scalar_type) = gnu_high_bound;
        }
    }

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

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

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

  /* If we are not defining this type, see if it's on one of the lists of
     incomplete types.  If so, handle the list entry now.  */
  if (is_type && !definition)
    {
      struct incomplete *p;

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

      for (p = defer_limited_with_list; p; p = p->next)
        if (p->old_type
            && (Non_Limited_View (p->full_type) == gnat_entity
                || Full_View (p->full_type) == gnat_entity))
          {
            update_pointer_to (TYPE_MAIN_VARIANT (p->old_type),
                               TREE_TYPE (gnu_decl));
            if (TYPE_DUMMY_IN_PROFILE_P (p->old_type))
              update_profiles_with (p->old_type);
            p->old_type = NULL_TREE;
          }
    }

  if (this_global)
    force_global--;

  /* If this is a packed array type whose original array type is itself
     an Itype without freeze node, make sure the latter is processed.  */
  if (Is_Packed_Array_Impl_Type (gnat_entity)
      && Is_Itype (Original_Array_Type (gnat_entity))
      && No (Freeze_Node (Original_Array_Type (gnat_entity)))
      && !present_gnu_tree (Original_Array_Type (gnat_entity)))
    gnat_to_gnu_entity (Original_Array_Type (gnat_entity), NULL_TREE, false);

  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, false);

  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, false);
  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 (TYPE_IS_PADDING_P (type))
    type = TREE_TYPE (TYPE_FIELDS (type));

  return type;
}

/* Return whether the E_Subprogram_Type/E_Function/E_Procedure GNAT_ENTITY is
   a C++ imported method or equivalent.

   We use the predicate on 32-bit x86/Windows to find out whether we need to
   use the "thiscall" calling convention for GNAT_ENTITY.  This convention is
   used for C++ methods (functions with METHOD_TYPE) by the back-end.  */

bool
is_cplusplus_method (Entity_Id gnat_entity)
{
  /* A constructor is a method on the C++ side.  We deal with it now because
     it is declared without the 'this' parameter in the sources and, although
     the front-end will create a version with the 'this' parameter for code
     generation purposes, we want to return true for both versions.  */
  if (Is_Constructor (gnat_entity))
    return true;

  /* Check that the subprogram has C++ convention.  */
  if (Convention (gnat_entity) != Convention_CPP)
    return false;

  /* And that the type of the first parameter (indirectly) has it too.  */
  Entity_Id gnat_first = First_Formal (gnat_entity);
  if (No (gnat_first))
    return false;

  Entity_Id gnat_type = Etype (gnat_first);
  if (Is_Access_Type (gnat_type))
    gnat_type = Directly_Designated_Type (gnat_type);
  if (Convention (gnat_type) != Convention_CPP)
    return false;

  /* This is the main case: a C++ virtual method imported as a primitive
     operation of a tagged type.  */
  if (Is_Dispatching_Operation (gnat_entity))
    return true;

  /* This is set on the E_Subprogram_Type built for a dispatching call.  */
  if (Is_Dispatch_Table_Entity (gnat_entity))
    return true;

  /* A thunk needs to be handled like its associated primitive operation.  */
  if (Is_Subprogram (gnat_entity) && Is_Thunk (gnat_entity))
    return true;

  /* Now on to the annoying case: a C++ non-virtual method, imported either
     as a non-primitive operation of a tagged type or as a primitive operation
     of an untagged type.  We cannot reliably differentiate these cases from
     their static member or regular function equivalents in Ada, so we ask
     the C++ side through the mangled name of the function, as the implicit
     'this' parameter is not encoded in the mangled name of a method.  */
  if (Is_Subprogram (gnat_entity) && Present (Interface_Name (gnat_entity)))
    {
      String_Pointer sp = { NULL, NULL };
      Get_External_Name (gnat_entity, false, sp);

      void *mem;
      struct demangle_component *cmp
        = cplus_demangle_v3_components (Name_Buffer,
                                        DMGL_GNU_V3
                                        | DMGL_TYPES
                                        | DMGL_PARAMS
                                        | DMGL_RET_DROP,
                                        &mem);
      if (!cmp)
        return false;

      /* We need to release MEM once we have a successful demangling.  */
      bool ret = false;

      if (cmp->type == DEMANGLE_COMPONENT_TYPED_NAME
          && cmp->u.s_binary.right->type == DEMANGLE_COMPONENT_FUNCTION_TYPE
          && (cmp = cmp->u.s_binary.right->u.s_binary.right) != NULL
          && cmp->type == DEMANGLE_COMPONENT_ARGLIST)
        {
          /* Make sure there is at least one parameter in C++ too.  */
          if (cmp->u.s_binary.left)
            {
              unsigned int n_ada_args = 0;
              do {
                n_ada_args++;
                gnat_first = Next_Formal (gnat_first);
              } while (Present (gnat_first));

              unsigned int n_cpp_args = 0;
              do {
                n_cpp_args++;
                cmp = cmp->u.s_binary.right;
              } while (cmp);

              if (n_cpp_args < n_ada_args)
                ret = true;
            }
          else
            ret = true;
        }

      free (mem);

      return ret;
    }

  return false;
}

/* Finalize the processing of From_Limited_With incomplete types.  */

void
finalize_from_limited_with (void)
{
  struct incomplete *p, *next;

  p = defer_limited_with_list;
  defer_limited_with_list = NULL;

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

      if (p->old_type)
        {
          update_pointer_to (TYPE_MAIN_VARIANT (p->old_type),
                             gnat_to_gnu_type (p->full_type));
          if (TYPE_DUMMY_IN_PROFILE_P (p->old_type))
            update_profiles_with (p->old_type);
        }

      free (p);
    }
}

/* 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.  */

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:
      if (Present (Equivalent_Type (gnat_entity)))
        gnat_equiv = Equivalent_Type (gnat_entity);
      break;

    case E_Class_Wide_Type:
      gnat_equiv = Root_Type (gnat_entity);
      break;

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

    default:
      break;
    }

  return gnat_equiv;
}

/* Return a GCC tree for a type corresponding to the component type of the
   array type or subtype GNAT_ARRAY.  DEFINITION is true if this component
   is for an array being defined.  DEBUG_INFO_P is true if we need to write
   debug information for other types that we may create in the process.  */

static tree
gnat_to_gnu_component_type (Entity_Id gnat_array, bool definition,
                            bool debug_info_p)
{
  const Entity_Id gnat_type = Component_Type (gnat_array);
  tree gnu_type = gnat_to_gnu_type (gnat_type);
  tree gnu_comp_size;
  unsigned int max_align;

  /* If an alignment is specified, use it as a cap on the component type
     so that it can be honored for the whole type.  But ignore it for the
     original type of packed array types.  */
  if (No (Packed_Array_Impl_Type (gnat_array))
      && Known_Alignment (gnat_array))
    max_align = validate_alignment (Alignment (gnat_array), gnat_array, 0);
  else
    max_align = 0;

  /* Try to get a smaller form of the component if needed.  */
  if ((Is_Packed (gnat_array) || Has_Component_Size_Clause (gnat_array))
      && !Is_Bit_Packed_Array (gnat_array)
      && !Has_Aliased_Components (gnat_array)
      && !Strict_Alignment (gnat_type)
      && RECORD_OR_UNION_TYPE_P (gnu_type)
      && !TYPE_FAT_POINTER_P (gnu_type)
      && tree_fits_uhwi_p (TYPE_SIZE (gnu_type)))
    gnu_type = make_packable_type (gnu_type, false, max_align);

  if (Has_Atomic_Components (gnat_array))
    check_ok_for_atomic_type (gnu_type, gnat_array, true);

  /* Get and validate any specified Component_Size.  */
  gnu_comp_size
    = validate_size (Component_Size (gnat_array), gnu_type, gnat_array,
                     Is_Bit_Packed_Array (gnat_array) ? TYPE_DECL : VAR_DECL,
                     true, Has_Component_Size_Clause (gnat_array));

  /* If the array has aliased components and the component size can be zero,
     force at least unit size to ensure that the components have distinct
     addresses.  */
  if (!gnu_comp_size
      && Has_Aliased_Components (gnat_array)
      && (integer_zerop (TYPE_SIZE (gnu_type))
          || (TREE_CODE (gnu_type) == ARRAY_TYPE
              && !TREE_CONSTANT (TYPE_SIZE (gnu_type)))))
    gnu_comp_size
      = size_binop (MAX_EXPR, TYPE_SIZE (gnu_type), bitsize_unit_node);

  /* If the component type is a RECORD_TYPE that has a self-referential size,
     then use the maximum size for the component 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);

  /* Honor the component size.  This is not needed for bit-packed arrays.  */
  if (gnu_comp_size && !Is_Bit_Packed_Array (gnat_array))
    {
      tree orig_type = gnu_type;

      gnu_type = make_type_from_size (gnu_type, gnu_comp_size, false);
      if (max_align > 0 && TYPE_ALIGN (gnu_type) > max_align)
        gnu_type = orig_type;
      else
        orig_type = gnu_type;

      gnu_type = maybe_pad_type (gnu_type, gnu_comp_size, 0, gnat_array,
                                 true, 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_type && !DECL_P (TYPE_NAME (gnu_type)))
        create_type_decl (TYPE_NAME (gnu_type), gnu_type, true, debug_info_p,
                          gnat_array);
    }

  /* If the component type is a padded type made for a non-bit-packed array
     of scalars with reverse storage order, we need to propagate the reverse
     storage order to the padding type since it is the innermost enclosing
     aggregate type around the scalar.  */
  if (TYPE_IS_PADDING_P (gnu_type)
      && Reverse_Storage_Order (gnat_array)
      && !Is_Bit_Packed_Array (gnat_array)
      && Is_Scalar_Type (gnat_type))
    gnu_type = set_reverse_storage_order_on_pad_type (gnu_type);

  if (Has_Volatile_Components (gnat_array))
    {
      const int quals
        = TYPE_QUAL_VOLATILE
          | (Has_Atomic_Components (gnat_array) ? TYPE_QUAL_ATOMIC : 0);
      gnu_type = change_qualified_type (gnu_type, quals);
    }

  return gnu_type;
}

/* Return a GCC tree for a parameter corresponding to GNAT_PARAM, to be placed
   in the parameter list of GNAT_SUBPROG.  GNU_PARAM_TYPE is the GCC tree for
   the type of the parameter.  FIRST is true if this is the first parameter in
   the list of GNAT_SUBPROG.  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 the 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, tree gnu_param_type, bool first,
                   Entity_Id gnat_subprog, bool *cico)
{
  Entity_Id gnat_param_type = Etype (gnat_param);
  Mechanism_Type mech = Mechanism (gnat_param);
  tree gnu_param_name = get_entity_name (gnat_param);
  bool foreign = Has_Foreign_Convention (gnat_subprog);
  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;
  bool by_ref = false;
  bool restricted_aliasing_p = false;
  location_t saved_location = input_location;
  tree gnu_param;

  /* Make sure to use the proper SLOC for vector ABI warnings.  */
  if (VECTOR_TYPE_P (gnu_param_type))
    Sloc_to_locus (Sloc (gnat_subprog), &input_location);

  /* 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 the
     argument "as is".  */
  if (Convention (gnat_subprog) == Convention_Intrinsic
      && Present (Interface_Name (gnat_subprog)))
    mech = By_Copy;

  /* Handle the first parameter of a valued procedure specially: it's a copy
     mechanism for which the parameter is never allocated.  */
  else if (first && Is_Valued_Procedure (gnat_subprog))
    {
      gcc_assert (Ekind (gnat_param) == E_Out_Parameter);
      mech = By_Copy;
      by_return = true;
    }

  /* Or else, 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)
    ;

  /* Positive mechanism means by copy for sufficiently small parameters.  */
  else if (mech > 0)
    {
      if (TREE_CODE (gnu_param_type) == UNCONSTRAINED_ARRAY_TYPE
          || TREE_CODE (TYPE_SIZE (gnu_param_type)) != INTEGER_CST
          || compare_tree_int (TYPE_SIZE (gnu_param_type), mech) > 0)
        mech = By_Reference;
      else
        mech = By_Copy;
    }

  /* Otherwise, it's an unsupported mechanism so error out.  */
  else
    {
      post_error ("unsupported mechanism for&", gnat_param);
      mech = Default;
    }

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

      if (foreign
          || (!must_pass_by_ref (unpadded_type)
              && mech != By_Reference
              && (mech == By_Copy || !default_pass_by_ref (unpadded_type))
              && TYPE_ALIGN (unpadded_type) >= TYPE_ALIGN (gnu_param_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 a self-referential type, the type
     can be very complex, so skip it for now.  */
  if (ro_param && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_param_type)))
    gnu_param_type = change_qualified_type (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))));

  /* Arrays are passed as pointers to element type for foreign conventions.  */
  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
          = change_qualified_type (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_IS_FAT_POINTER_P (gnu_param_type))
    gnu_param_type
      = make_type_from_size (gnu_param_type, size_int (POINTER_SIZE), 0);

  /* If we were requested or muss 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 (mech == By_Reference
           || must_pass_by_ref (gnu_param_type)
           || (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)))))
    {
      /* We take advantage of 6.2(12) by considering that references built for
         parameters whose type isn't by-ref and for which the mechanism hasn't
         been forced to by-ref allow only a restricted form of aliasing.  */
      restricted_aliasing_p
        = !TYPE_IS_BY_REFERENCE_P (gnu_param_type) && mech != By_Reference;
      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;

  input_location = saved_location;

  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.  Note that scalars can
     be given implicit initial values using the Default_Value aspect.

     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
          || (!POINTER_TYPE_P (gnu_param_type)
              && !AGGREGATE_TYPE_P (gnu_param_type)
              && !Has_Default_Aspect (gnat_param_type)))
      && !(Is_Array_Type (gnat_param_type)
           && Is_Packed (gnat_param_type)
           && Is_Composite_Type (Component_Type (gnat_param_type))))
    return gnu_param_type;

  gnu_param = create_param_decl (gnu_param_name, gnu_param_type);
  TREE_READONLY (gnu_param) = 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_POINTS_TO_READONLY_P (gnu_param)
    = (ro_param && (by_ref || by_component_ptr));
  DECL_CAN_NEVER_BE_NULL_P (gnu_param) = Can_Never_Be_Null (gnat_param);
  DECL_RESTRICTED_ALIASING_P (gnu_param) = restricted_aliasing_p;
  Sloc_to_locus (Sloc (gnat_param), &DECL_SOURCE_LOCATION (gnu_param));

  /* 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;
}

/* Associate GNAT_SUBPROG with GNU_TYPE, which must be a dummy type, so that
   GNAT_SUBPROG is updated when GNU_TYPE is completed.

   Ada 2012 (AI05-019) says that freezing a subprogram does not always freeze
   the corresponding profile, which means that, by the time the freeze node
   of the subprogram is encountered, types involved in its profile may still
   be not yet frozen.  That's why we need to update GNAT_SUBPROG when we see
   the freeze node of types involved in its profile, either types of formal
   parameters or the return type.  */

static void
associate_subprog_with_dummy_type (Entity_Id gnat_subprog, tree gnu_type)
{
  gcc_assert (TYPE_IS_DUMMY_P (gnu_type));

  struct tree_entity_vec_map in;
  in.base.from = gnu_type;
  struct tree_entity_vec_map **slot
    = dummy_to_subprog_map->find_slot (&in, INSERT);
  if (!*slot)
    {
      tree_entity_vec_map *e = ggc_alloc<tree_entity_vec_map> ();
      e->base.from = gnu_type;
      e->to = NULL;
      *slot = e;
    }

  /* Even if there is already a slot for GNU_TYPE, we need to set the flag
     because the vector might have been just emptied by update_profiles_with.
     This can happen when there are 2 freeze nodes associated with different
     views of the same type; the type will be really complete only after the
     second freeze node is encountered.  */
  TYPE_DUMMY_IN_PROFILE_P (gnu_type) = 1;

  vec<Entity_Id, va_gc_atomic> *v = (*slot)->to;

  /* Make sure GNAT_SUBPROG is not associated twice with the same dummy type,
     since this would mean updating twice its profile.  */
  if (v)
    {
      const unsigned len = v->length ();
      unsigned int l = 0, u = len;

      /* Entity_Id is a simple integer so we can implement a stable order on
         the vector with an ordered insertion scheme and binary search.  */
      while (l < u)
        {
          unsigned int m = (l + u) / 2;
          int diff = (int) (*v)[m] - (int) gnat_subprog;
          if (diff > 0)
            u = m;
          else if (diff < 0)
            l = m + 1;
          else
            return;
        }

      /* l == u and therefore is the insertion point.  */
      vec_safe_insert (v, l, gnat_subprog);
    }
  else
    vec_safe_push (v, gnat_subprog);

  (*slot)->to = v;
}

/* Update the GCC tree previously built for the profile of GNAT_SUBPROG.  */

static void
update_profile (Entity_Id gnat_subprog)
{
  tree gnu_param_list;
  tree gnu_type = gnat_to_gnu_subprog_type (gnat_subprog, true,
                                            Needs_Debug_Info (gnat_subprog),
                                            &gnu_param_list);
  if (DECL_P (gnu_type))
    {
      /* Builtins cannot have their address taken so we can reset them.  */
      gcc_assert (DECL_BUILT_IN (gnu_type));
      save_gnu_tree (gnat_subprog, NULL_TREE, false);
      save_gnu_tree (gnat_subprog, gnu_type, false);
      return;
    }

  tree gnu_subprog = get_gnu_tree (gnat_subprog);

  TREE_TYPE (gnu_subprog) = gnu_type;

  /* If GNAT_SUBPROG is an actual subprogram, GNU_SUBPROG is a FUNCTION_DECL
     and needs to be adjusted too.  */
  if (Ekind (gnat_subprog) != E_Subprogram_Type)
    {
      tree gnu_entity_name = get_entity_name (gnat_subprog);
      tree gnu_ext_name
        = gnu_ext_name_for_subprog (gnat_subprog, gnu_entity_name);

      DECL_ARGUMENTS (gnu_subprog) = gnu_param_list;
      finish_subprog_decl (gnu_subprog, gnu_ext_name, gnu_type);
    }
}

/* Update the GCC trees previously built for the profiles involving GNU_TYPE,
   a dummy type which appears in profiles.  */

void
update_profiles_with (tree gnu_type)
{
  struct tree_entity_vec_map in;
  in.base.from = gnu_type;
  struct tree_entity_vec_map *e = dummy_to_subprog_map->find (&in);
  gcc_assert (e);
  vec<Entity_Id, va_gc_atomic> *v = e->to;
  e->to = NULL;

  /* The flag needs to be reset before calling update_profile, in case
     associate_subprog_with_dummy_type is again invoked on GNU_TYPE.  */
  TYPE_DUMMY_IN_PROFILE_P (gnu_type) = 0;

  unsigned int i;
  Entity_Id *iter;
  FOR_EACH_VEC_ELT (*v, i, iter)
    update_profile (*iter);

  vec_free (v);
}

/* Return the GCC tree for GNAT_TYPE present in the profile of a subprogram.

   Ada 2012 (AI05-0151) says that incomplete types coming from a limited
   context may now appear as parameter and result types.  As a consequence,
   we may need to defer their translation until after a freeze node is seen
   or to the end of the current unit.  We also aim at handling temporarily
   incomplete types created by the usual delayed elaboration scheme.  */

static tree
gnat_to_gnu_profile_type (Entity_Id gnat_type)
{
  /* This is the same logic as the E_Access_Type case of gnat_to_gnu_entity
     so the rationale is exposed in that place.  These processings probably
     ought to be merged at some point.  */
  Entity_Id gnat_equiv = Gigi_Equivalent_Type (gnat_type);
  const bool is_from_limited_with
    = (Is_Incomplete_Type (gnat_equiv)
       && From_Limited_With (gnat_equiv));
  Entity_Id gnat_full_direct_first
    = (is_from_limited_with
       ? Non_Limited_View (gnat_equiv)
       : (Is_Incomplete_Or_Private_Type (gnat_equiv)
          ? Full_View (gnat_equiv) : Empty));
  Entity_Id gnat_full_direct
    = ((is_from_limited_with
        && Present (gnat_full_direct_first)
        && Is_Private_Type (gnat_full_direct_first))
       ? Full_View (gnat_full_direct_first)
       : gnat_full_direct_first);
  Entity_Id gnat_full = Gigi_Equivalent_Type (gnat_full_direct);
  Entity_Id gnat_rep = Present (gnat_full) ? gnat_full : gnat_equiv;
  const bool in_main_unit = In_Extended_Main_Code_Unit (gnat_rep);
  tree gnu_type;

  if (Present (gnat_full) && present_gnu_tree (gnat_full))
    gnu_type = TREE_TYPE (get_gnu_tree (gnat_full));

  else if (is_from_limited_with
           && ((!in_main_unit
                && !present_gnu_tree (gnat_equiv)
                && Present (gnat_full)
                && (Is_Record_Type (gnat_full)
                    || Is_Array_Type (gnat_full)
                    || Is_Access_Type (gnat_full)))
               || (in_main_unit && Present (Freeze_Node (gnat_rep)))))
    {
      gnu_type = make_dummy_type (gnat_equiv);

      if (!in_main_unit)
        {
          struct incomplete *p = XNEW (struct incomplete);

          p->old_type = gnu_type;
          p->full_type = gnat_equiv;
          p->next = defer_limited_with_list;
          defer_limited_with_list = p;
        }
    }

  else if (type_annotate_only && No (gnat_equiv))
    gnu_type = void_type_node;

  else
    gnu_type = gnat_to_gnu_type (gnat_equiv);

  /* Access-to-unconstrained-array types need a special treatment.  */
  if (Is_Array_Type (gnat_rep) && !Is_Constrained (gnat_rep))
    {
      if (!TYPE_POINTER_TO (gnu_type))
        build_dummy_unc_pointer_types (gnat_equiv, gnu_type);
    }

  return gnu_type;
}

/* Return a GCC tree for a subprogram type corresponding to GNAT_SUBPROG.
   DEFINITION is true if this is for a subprogram being defined.  DEBUG_INFO_P
   is true if we need to write debug information for other types that we may
   create in the process.  Also set PARAM_LIST to the list of parameters.
   If GNAT_SUBPROG is bound to a GCC builtin, return the DECL for the builtin
   directly instead of its type.  */

static tree
gnat_to_gnu_subprog_type (Entity_Id gnat_subprog, bool definition,
                          bool debug_info_p, tree *param_list)
{
  const Entity_Kind kind = Ekind (gnat_subprog);
  Entity_Id gnat_return_type = Etype (gnat_subprog);
  Entity_Id gnat_param;
  tree gnu_type = present_gnu_tree (gnat_subprog)
                  ? TREE_TYPE (get_gnu_tree (gnat_subprog)) : NULL_TREE;
  tree gnu_return_type;
  tree gnu_param_type_list = NULL_TREE;
  tree gnu_param_list = NULL_TREE;
  /* Non-null for subprograms containing parameters passed by copy-in copy-out
     (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_DECL 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_cico_list = NULL_TREE;
  tree gnu_cico_return_type = NULL_TREE;
  /* Fields in return type of procedure with copy-in copy-out parameters.  */
  tree gnu_field_list = NULL_TREE;
  /* 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 = (Back_End_Exceptions () && Is_Pure (gnat_subprog));
  bool return_by_direct_ref_p = false;
  bool return_by_invisi_ref_p = false;
  bool return_unconstrained_p = false;
  bool incomplete_profile_p = false;
  unsigned int num;

  /* Look into the return type and get its associated GCC tree if it is not
     void, and then compute various flags for the subprogram type.  But make
     sure not to do this processing multiple times.  */
  if (Ekind (gnat_return_type) == E_Void)
    gnu_return_type = void_type_node;

  else if (gnu_type
           && TREE_CODE (gnu_type) == FUNCTION_TYPE
           && !TYPE_IS_DUMMY_P (TREE_TYPE (gnu_type)))
    {
      gnu_return_type = TREE_TYPE (gnu_type);
      return_unconstrained_p = TYPE_RETURN_UNCONSTRAINED_P (gnu_type);
      return_by_direct_ref_p = TYPE_RETURN_BY_DIRECT_REF_P (gnu_type);
      return_by_invisi_ref_p = TREE_ADDRESSABLE (gnu_type);
    }

  else
    {
      /* For foreign convention subprograms, return System.Address as void *
         or equivalent.  Note that this comprises GCC builtins.  */
      if (Has_Foreign_Convention (gnat_subprog)
          && Is_Descendant_Of_Address (gnat_return_type))
        gnu_return_type = ptr_type_node;
      else
        gnu_return_type = gnat_to_gnu_profile_type (gnat_return_type);

      /* If this function returns by reference, make the actual return type
         the reference type and make a note of that.  */
      if (Returns_By_Ref (gnat_subprog))
        {
          gnu_return_type = build_reference_type (gnu_return_type);
          return_by_direct_ref_p = true;
        }

      /* If the return type is an unconstrained array type, the return value
         will be allocated on the secondary stack so the actual return type
         is the fat pointer type.  */
      else if (TREE_CODE (gnu_return_type) == UNCONSTRAINED_ARRAY_TYPE)
        {
          gnu_return_type = TYPE_REFERENCE_TO (gnu_return_type);
          return_unconstrained_p = true;
        }

      /* This is the same unconstrained array case, but for a dummy type.  */
      else if (TYPE_REFERENCE_TO (gnu_return_type)
               && TYPE_IS_FAT_POINTER_P (TYPE_REFERENCE_TO (gnu_return_type)))
        {
          gnu_return_type = TYPE_REFERENCE_TO (gnu_return_type);
          return_unconstrained_p = true;
        }

      /* Likewise, if the return type requires a transient scope, the return
         value will also be allocated on the secondary stack so the actual
         return type is the reference type.  */
      else if (Requires_Transient_Scope (gnat_return_type))
        {
          gnu_return_type = build_reference_type (gnu_return_type);
          return_unconstrained_p = true;
        }

      /* If the Mechanism is By_Reference, ensure this function uses the
         target's by-invisible-reference mechanism, which may not be the
         same as above (e.g. it might be passing an extra parameter).  */
      else if (kind == E_Function && Mechanism (gnat_subprog) == By_Reference)
        return_by_invisi_ref_p = true;

      /* Likewise, if the return type is itself By_Reference.  */
      else if (TYPE_IS_BY_REFERENCE_P (gnu_return_type))
        return_by_invisi_ref_p = true;

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

      /* If the return type is unconstrained, it must have a maximum size.
         Use the padded type as the effective return type.  And ensure the
         function uses the target's by-invisible-reference mechanism to
         avoid copying too much data when it returns.  */
      if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_return_type)))
        {
          tree orig_type = gnu_return_type;
          tree max_return_size = max_size (TYPE_SIZE (gnu_return_type), true);

          /* If the size overflows to 0, set it to an arbitrary positive
             value so that assignments in the type are preserved.  Their
             actual size is independent of this positive value.  */
          if (TREE_CODE (max_return_size) == INTEGER_CST
              && TREE_OVERFLOW (max_return_size)
              && integer_zerop (max_return_size))
            {
              max_return_size = copy_node (bitsize_unit_node);
              TREE_OVERFLOW (max_return_size) = 1;
            }

          gnu_return_type = maybe_pad_type (gnu_return_type, max_return_size,
                                            0, gnat_subprog, false, false,
                                            definition, true);

          /* Declare it now since it will never be declared otherwise.  This
             is necessary to ensure that its subtrees are properly marked.  */
          if (gnu_return_type != orig_type
              && !DECL_P (TYPE_NAME (gnu_return_type)))
            create_type_decl (TYPE_NAME (gnu_return_type), gnu_return_type,
                              true, debug_info_p, gnat_subprog);

          return_by_invisi_ref_p = true;
        }

      /* If the return type has a size that overflows, we usually cannot have
         a function that returns that type.  This usage doesn't really make
         sense anyway, so issue an error here.  */
      if (!return_by_invisi_ref_p
          && TYPE_SIZE_UNIT (gnu_return_type)
          && TREE_CODE (TYPE_SIZE_UNIT (gnu_return_type)) == INTEGER_CST
          && !valid_constant_size_p (TYPE_SIZE_UNIT (gnu_return_type)))
        {
          post_error ("cannot return type whose size overflows", gnat_subprog);
          gnu_return_type = copy_type (gnu_return_type);
          TYPE_SIZE (gnu_return_type) = bitsize_zero_node;
          TYPE_SIZE_UNIT (gnu_return_type) = size_zero_node;
        }

      /* If the return type is incomplete, there are 2 cases: if the function
         returns by reference, then the return type is only linked indirectly
         in the profile, so the profile can be seen as complete since it need
         not be further modified, only the reference types need be adjusted;
         otherwise the profile is incomplete and need be adjusted too.  */
      if (TYPE_IS_DUMMY_P (gnu_return_type))
        {
          associate_subprog_with_dummy_type (gnat_subprog, gnu_return_type);
          incomplete_profile_p = true;
        }

      if (kind == E_Function)
        Set_Mechanism (gnat_subprog, return_unconstrained_p
                                     || return_by_direct_ref_p
                                     || return_by_invisi_ref_p
                                     ? By_Reference : By_Copy);
    }

  /* A procedure (something that doesn't return anything) shouldn't be
     considered const since there would be no reason for calling such a
     subprogram.  Note that procedures with Out (or In Out) parameters
     have already been converted into a function with a return type.
     Similarly, if the function returns an unconstrained type, then the
     function will allocate the return value on the secondary stack and
     thus calls to it cannot be CSE'ed, lest the stack be reclaimed.  */
  if (TREE_CODE (gnu_return_type) == VOID_TYPE || return_unconstrained_p)
    const_flag = false;

  /* Loop over the parameters and get their associated GCC tree.  While doing
     this, build a copy-in copy-out structure if we need one.  */
  for (gnat_param = First_Formal_With_Extras (gnat_subprog), num = 0;
       Present (gnat_param);
       gnat_param = Next_Formal_With_Extras (gnat_param), num++)
    {
      const bool mech_is_by_ref
        = Mechanism (gnat_param) == By_Reference
          && !(num == 0 && Is_Valued_Procedure (gnat_subprog));
      tree gnu_param_name = get_entity_name (gnat_param);
      tree gnu_param, gnu_param_type;
      bool cico = false;

      /* Fetch an existing parameter with complete type and reuse it.  But we
         didn't save the CICO property so we can only do it for In parameters
         or parameters passed by reference.  */
      if ((Ekind (gnat_param) == E_In_Parameter || mech_is_by_ref)
          && present_gnu_tree (gnat_param)
          && (gnu_param = get_gnu_tree (gnat_param))
          && !TYPE_IS_DUMMY_P (TREE_TYPE (gnu_param)))
        {
          DECL_CHAIN (gnu_param) = NULL_TREE;
          gnu_param_type = TREE_TYPE (gnu_param);
        }

      /* Otherwise translate the parameter type and act accordingly.  */
      else
        {
          Entity_Id gnat_param_type = Etype (gnat_param);

          /* For foreign convention subprograms, pass System.Address as void *
             or equivalent.  Note that this comprises GCC builtins.  */
          if (Has_Foreign_Convention (gnat_subprog)
              && Is_Descendant_Of_Address (gnat_param_type))
            gnu_param_type = ptr_type_node;
          else
            gnu_param_type = gnat_to_gnu_profile_type (gnat_param_type);

          /* If the parameter type is incomplete, there are 2 cases: if it is
             passed by reference, then the type is only linked indirectly in
             the profile, so the profile can be seen as complete since it need
             not be further modified, only the reference type need be adjusted;
             otherwise the profile is incomplete and need be adjusted too.  */
          if (TYPE_IS_DUMMY_P (gnu_param_type))
            {
              Node_Id gnat_decl;

              if (mech_is_by_ref
                  || (TYPE_REFERENCE_TO (gnu_param_type)
                      && TYPE_IS_FAT_POINTER_P
                         (TYPE_REFERENCE_TO (gnu_param_type)))
                  || TYPE_IS_BY_REFERENCE_P (gnu_param_type))
                {
                  gnu_param_type = build_reference_type (gnu_param_type);
                  gnu_param
                    = create_param_decl (gnu_param_name, gnu_param_type);
                  TREE_READONLY (gnu_param) = 1;
                  DECL_BY_REF_P (gnu_param) = 1;
                  DECL_POINTS_TO_READONLY_P (gnu_param)
                    = (Ekind (gnat_param) == E_In_Parameter
                       && !Address_Taken (gnat_param));
                  Set_Mechanism (gnat_param, By_Reference);
                  Sloc_to_locus (Sloc (gnat_param),
                                 &DECL_SOURCE_LOCATION (gnu_param));
                }

              /* ??? This is a kludge to support null procedures in spec taking
                 a parameter with an untagged incomplete type coming from a
                 limited context.  The front-end creates a body without knowing
                 anything about the non-limited view, which is illegal Ada and
                 cannot be supported.  Create a parameter with a fake type.  */
              else if (kind == E_Procedure
                       && (gnat_decl = Parent (gnat_subprog))
                       && Nkind (gnat_decl) == N_Procedure_Specification
                       && Null_Present (gnat_decl)
                       && Is_Incomplete_Type (gnat_param_type))
                gnu_param = create_param_decl (gnu_param_name, ptr_type_node);

              else
                {
                  /* Build a minimal PARM_DECL without DECL_ARG_TYPE so that
                     Call_to_gnu will stop if it encounters the PARM_DECL.  */
                  gnu_param
                    = build_decl (input_location, PARM_DECL, gnu_param_name,
                                  gnu_param_type);
                  associate_subprog_with_dummy_type (gnat_subprog,
                                                     gnu_param_type);
                  incomplete_profile_p = true;
                }
            }

          /* Otherwise build the parameter declaration normally.  */
          else
            {
              gnu_param
                = gnat_to_gnu_param (gnat_param, gnu_param_type, num == 0,
                                     gnat_subprog, &cico);

              /* 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 we have a GCC tree for the parameter, register it.  */
      save_gnu_tree (gnat_param, NULL_TREE, false);
      if (gnu_param)
        {
          gnu_param_type_list
            = tree_cons (NULL_TREE, gnu_param_type, gnu_param_type_list);
          gnu_param_list = chainon (gnu_param, gnu_param_list);
          save_gnu_tree (gnat_param, gnu_param, false);

          /* If a parameter is a pointer, a 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_IS_FAT_POINTER_P (gnu_param_type))
            const_flag = false;
        }

      /* If the parameter uses the copy-in copy-out mechanism, allocate a field
         for it in the return type and register the association.  */
      if (cico && !incomplete_profile_p)
        {
          if (!gnu_cico_list)
            {
              gnu_cico_return_type = make_node (RECORD_TYPE);

              /* If this is a function, we also need a field for the
                 return value to be placed.  */
              if (!VOID_TYPE_P (gnu_return_type))
                {
                  tree gnu_field
                    = create_field_decl (get_identifier ("RETVAL"),
                                         gnu_return_type,
                                         gnu_cico_return_type, NULL_TREE,
                                         NULL_TREE, 0, 0);
                  Sloc_to_locus (Sloc (gnat_subprog),
                                 &DECL_SOURCE_LOCATION (gnu_field));
                  gnu_field_list = gnu_field;
                  gnu_cico_list
                    = tree_cons (gnu_field, void_type_node, NULL_TREE);
                }

              TYPE_NAME (gnu_cico_return_type) = get_identifier ("RETURN");
              /* Set a default alignment to speed up accesses.  But we should
                 not increase the size of the structure too much, lest it does
                 not fit in return registers anymore.  */
              SET_TYPE_ALIGN (gnu_cico_return_type,
                              get_mode_alignment (ptr_mode));
            }

          tree gnu_field
            = create_field_decl (gnu_param_name, gnu_param_type,
                                 gnu_cico_return_type, NULL_TREE, NULL_TREE,
                                 0, 0);
          Sloc_to_locus (Sloc (gnat_param),
                         &DECL_SOURCE_LOCATION (gnu_field));
          DECL_CHAIN (gnu_field) = gnu_field_list;
          gnu_field_list = gnu_field;
          gnu_cico_list = tree_cons (gnu_field, gnu_param, gnu_cico_list);
        }
    }

  /* If the subprogram uses the copy-in copy-out mechanism, possibly adjust
     and finish up the return type.  */
  if (gnu_cico_list && !incomplete_profile_p)
    {
      /* If we have a CICO list but it has only one entry, we convert
         this function into a function that returns this object.  */
      if (list_length (gnu_cico_list) == 1)
        gnu_cico_return_type = TREE_TYPE (TREE_PURPOSE (gnu_cico_list));

      /* Do not finalize the return type if the subprogram is stubbed
         since structures are incomplete for the back-end.  */
      else if (Convention (gnat_subprog) != Convention_Stubbed)
        {
          finish_record_type (gnu_cico_return_type, nreverse (gnu_field_list),
                              0, false);

          /* Try to promote the mode of the return type if it is passed
             in registers, again to speed up accesses.  */
          if (TYPE_MODE (gnu_cico_return_type) == BLKmode
              && !targetm.calls.return_in_memory (gnu_cico_return_type,
                                                  NULL_TREE))
            {
              unsigned int size
                = TREE_INT_CST_LOW (TYPE_SIZE (gnu_cico_return_type));
              unsigned int i = BITS_PER_UNIT;
              scalar_int_mode mode;

              while (i < size)
                i <<= 1;
              if (int_mode_for_size (i, 0).exists (&mode))
                {
                  SET_TYPE_MODE (gnu_cico_return_type, mode);
                  SET_TYPE_ALIGN (gnu_cico_return_type,
                                  GET_MODE_ALIGNMENT (mode));
                  TYPE_SIZE (gnu_cico_return_type)
                    = bitsize_int (GET_MODE_BITSIZE (mode));
                  TYPE_SIZE_UNIT (gnu_cico_return_type)
                    = size_int (GET_MODE_SIZE (mode));
                }
            }

          if (debug_info_p)
            rest_of_record_type_compilation (gnu_cico_return_type);
        }

      gnu_return_type = gnu_cico_return_type;
    }

  /* The lists have been built in reverse.  */
  gnu_param_type_list = nreverse (gnu_param_type_list);
  gnu_param_type_list = chainon (gnu_param_type_list, void_list_node);
  *param_list = nreverse (gnu_param_list);
  gnu_cico_list = nreverse (gnu_cico_list);

  /* If the profile is incomplete, we only set the (temporary) return and
     parameter types; otherwise, we build the full type.  In either case,
     we reuse an already existing GCC tree that we built previously here.  */
  if (incomplete_profile_p)
    {
      if (gnu_type && TREE_CODE (gnu_type) == FUNCTION_TYPE)
        ;
      else
        gnu_type = make_node (FUNCTION_TYPE);
      TREE_TYPE (gnu_type) = gnu_return_type;
      TYPE_ARG_TYPES (gnu_type) = gnu_param_type_list;
      TYPE_RETURN_UNCONSTRAINED_P (gnu_type) = return_unconstrained_p;
      TYPE_RETURN_BY_DIRECT_REF_P (gnu_type) = return_by_direct_ref_p;
      TREE_ADDRESSABLE (gnu_type) = return_by_invisi_ref_p;
    }
  else
    {
      if (gnu_type && TREE_CODE (gnu_type) == FUNCTION_TYPE)
        {
          TREE_TYPE (gnu_type) = gnu_return_type;
          TYPE_ARG_TYPES (gnu_type) = gnu_param_type_list;
          TYPE_CI_CO_LIST (gnu_type) = gnu_cico_list;
          TYPE_RETURN_UNCONSTRAINED_P (gnu_type) = return_unconstrained_p;
          TYPE_RETURN_BY_DIRECT_REF_P (gnu_type) = return_by_direct_ref_p;
          TREE_ADDRESSABLE (gnu_type) = return_by_invisi_ref_p;
          TYPE_CANONICAL (gnu_type) = gnu_type;
          layout_type (gnu_type);
        }
      else
        {
          gnu_type
            = build_function_type (gnu_return_type, gnu_param_type_list);

          /* GNU_TYPE may be shared since GCC hashes types.  Unshare it if it
             has a different TYPE_CI_CO_LIST or flags.  */
          if (!fntype_same_flags_p (gnu_type, gnu_cico_list,
                                    return_unconstrained_p,
                                    return_by_direct_ref_p,
                                    return_by_invisi_ref_p))
            {
              gnu_type = copy_type (gnu_type);
              TYPE_CI_CO_LIST (gnu_type) = gnu_cico_list;
              TYPE_RETURN_UNCONSTRAINED_P (gnu_type) = return_unconstrained_p;
              TYPE_RETURN_BY_DIRECT_REF_P (gnu_type) = return_by_direct_ref_p;
              TREE_ADDRESSABLE (gnu_type) = return_by_invisi_ref_p;
            }
        }

      if (const_flag)
        gnu_type = change_qualified_type (gnu_type, TYPE_QUAL_CONST);

      if (No_Return (gnat_subprog))
        gnu_type = change_qualified_type (gnu_type, TYPE_QUAL_VOLATILE);

      /* If this subprogram is expectedly bound to a GCC builtin, fetch the
         corresponding DECL node and check the parameter association.  */
      if (Convention (gnat_subprog) == Convention_Intrinsic
          && Present (Interface_Name (gnat_subprog)))
        {
          tree gnu_ext_name = create_concat_name (gnat_subprog, NULL);
          tree gnu_builtin_decl = builtin_decl_for (gnu_ext_name);

          /* If we have a builtin DECL for that function, use it.  Check if
             the profiles are compatible and warn if they are not.  Note that
             the checker is expected to post diagnostics in this case.  */
          if (gnu_builtin_decl)
            {
              intrin_binding_t inb
                = { gnat_subprog, gnu_type, TREE_TYPE (gnu_builtin_decl) };

              if (!intrin_profiles_compatible_p (&inb))
                post_error
                  ("?profile of& doesn''t match the builtin it binds!",
                   gnat_subprog);

              return gnu_builtin_decl;
            }

          /* Inability to find the builtin DECL most often indicates a genuine
             mistake, but imports of unregistered intrinsics are sometimes used
             on purpose to allow hooking in alternate bodies; we post a warning
             conditioned on Wshadow in this case, to let developers be notified
             on demand without risking false positives with common default sets
             of options.  */
          if (warn_shadow)
            post_error ("?gcc intrinsic not found for&!", gnat_subprog);
        }
    }

  return gnu_type;
}

/* Return the external name for GNAT_SUBPROG given its entity name.  */

static tree
gnu_ext_name_for_subprog (Entity_Id gnat_subprog, tree gnu_entity_name)
{
  tree gnu_ext_name = create_concat_name (gnat_subprog, NULL);

  /* 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_subprog)) && gnu_ext_name == gnu_entity_name)
    gnu_ext_name = NULL_TREE;

  return gnu_ext_name;
}

/* Like build_qualified_type, but TYPE_QUALS is added to the existing
   qualifiers on TYPE.  */

static tree
change_qualified_type (tree type, int type_quals)
{
  /* Qualifiers must be put on the associated array type.  */
  if (TREE_CODE (type) == UNCONSTRAINED_ARRAY_TYPE)
    return type;

  return build_qualified_type (type, TYPE_QUALS (type) | type_quals);
}

/* Set TYPE_NONALIASED_COMPONENT on an array type built by means of
   build_nonshared_array_type.  */

static void
set_nonaliased_component_on_array_type (tree type)
{
  TYPE_NONALIASED_COMPONENT (type) = 1;
  TYPE_NONALIASED_COMPONENT (TYPE_CANONICAL (type)) = 1;
}

/* Set TYPE_REVERSE_STORAGE_ORDER on an array type built by means of
   build_nonshared_array_type.  */

static void
set_reverse_storage_order_on_array_type (tree type)
{
  TYPE_REVERSE_STORAGE_ORDER (type) = 1;
  TYPE_REVERSE_STORAGE_ORDER (TYPE_CANONICAL (type)) = 1;
}

/* 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 GNU_TYPE, which represents a dimension of
   GNAT_TYPE, has a non-aliased component in the back-end sense.  */

static bool
array_type_has_nonaliased_component (tree gnu_type, Entity_Id gnat_type)
{
  /* If the array type is not the innermost dimension of the GNAT type,
     then it has a non-aliased component.  */
  if (TREE_CODE (TREE_TYPE (gnu_type)) == ARRAY_TYPE
      && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_type)))
    return true;

  /* If the array type has an aliased component in the front-end sense,
     then it also has an aliased component in the back-end sense.  */
  if (Has_Aliased_Components (gnat_type))
    return false;

  /* If this is a derived type, then it has a non-aliased component if
     and only if its parent type also has one.  */
  if (Is_Derived_Type (gnat_type))
    {
      tree gnu_parent_type = gnat_to_gnu_type (Etype (gnat_type));
      int index;
      if (TREE_CODE (gnu_parent_type) == UNCONSTRAINED_ARRAY_TYPE)
        gnu_parent_type
          = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_parent_type))));
      for (index = Number_Dimensions (gnat_type) - 1; index > 0; index--)
        gnu_parent_type = TREE_TYPE (gnu_parent_type);
      return TYPE_NONALIASED_COMPONENT (gnu_parent_type);
    }

  /* Otherwise, rely exclusively on properties of the element type.  */
  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)
{
  /* Handle reference to a constant.  */
  if (Is_Entity_Name (gnat_address)
      && Ekind (Entity (gnat_address)) == E_Constant)
    {
      gnat_address = Constant_Value (Entity (gnat_address));
      if (No (gnat_address))
        return false;
    }

  /* Catch System'To_Address.  */
  if (Nkind (gnat_address) == N_Unchecked_Type_Conversion)
    gnat_address = Expression (gnat_address);

  return Compile_Time_Known_Value (gnat_address);
}

/* Return true if GNAT_RANGE, a N_Range node, cannot be superflat, i.e. if the
   inequality HB >= LB-1 is true.  LB and HB are the low and high bounds.  */

static bool
cannot_be_superflat (Node_Id gnat_range)
{
  Node_Id gnat_lb = Low_Bound (gnat_range), gnat_hb = High_Bound (gnat_range);
  Node_Id scalar_range;
  tree gnu_lb, gnu_hb, gnu_lb_minus_one;

  /* If the low bound is not constant, try to find an upper bound.  */
  while (Nkind (gnat_lb) != N_Integer_Literal
         && (Ekind (Etype (gnat_lb)) == E_Signed_Integer_Subtype
             || Ekind (Etype (gnat_lb)) == E_Modular_Integer_Subtype)
         && (scalar_range = Scalar_Range (Etype (gnat_lb)))
         && (Nkind (scalar_range) == N_Signed_Integer_Type_Definition
             || Nkind (scalar_range) == N_Range))
    gnat_lb = High_Bound (scalar_range);

  /* If the high bound is not constant, try to find a lower bound.  */
  while (Nkind (gnat_hb) != N_Integer_Literal
         && (Ekind (Etype (gnat_hb)) == E_Signed_Integer_Subtype
             || Ekind (Etype (gnat_hb)) == E_Modular_Integer_Subtype)
         && (scalar_range = Scalar_Range (Etype (gnat_hb)))
         && (Nkind (scalar_range) == N_Signed_Integer_Type_Definition
             || Nkind (scalar_range) == N_Range))
    gnat_hb = Low_Bound (scalar_range);

  /* If we have failed to find constant bounds, punt.  */
  if (Nkind (gnat_lb) != N_Integer_Literal
      || Nkind (gnat_hb) != N_Integer_Literal)
    return false;

  /* We need at least a signed 64-bit type to catch most cases.  */
  gnu_lb = UI_To_gnu (Intval (gnat_lb), sbitsizetype);
  gnu_hb = UI_To_gnu (Intval (gnat_hb), sbitsizetype);
  if (TREE_OVERFLOW (gnu_lb) || TREE_OVERFLOW (gnu_hb))
    return false;

  /* If the low bound is the smallest integer, nothing can be smaller.  */
  gnu_lb_minus_one = size_binop (MINUS_EXPR, gnu_lb, sbitsize_one_node);
  if (TREE_OVERFLOW (gnu_lb_minus_one))
    return true;

  return !tree_int_cst_lt (gnu_hb, gnu_lb_minus_one);
}

/* Return true if GNU_EXPR is (essentially) the address of a CONSTRUCTOR.  */

static bool
constructor_address_p (tree gnu_expr)
{
  while (TREE_CODE (gnu_expr) == NOP_EXPR
         || TREE_CODE (gnu_expr) == CONVERT_EXPR
         || TREE_CODE (gnu_expr) == NON_LVALUE_EXPR)
    gnu_expr = TREE_OPERAND (gnu_expr, 0);

  return (TREE_CODE (gnu_expr) == ADDR_EXPR
          && TREE_CODE (TREE_OPERAND (gnu_expr, 0)) == CONSTRUCTOR);
}

/* Return true if the size in units 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)
{
  /* We can allocate a fixed size if it is a valid for the middle-end.  */
  if (TREE_CODE (gnu_size) == INTEGER_CST)
    return valid_constant_size_p (gnu_size);

  /* We can allocate a variable size if this isn't a static allocation.  */
  else
    return !static_p;
}

/* Return true if GNU_EXPR needs a conversion to GNU_TYPE when used as the
   initial value of an object of GNU_TYPE.  */

static bool
initial_value_needs_conversion (tree gnu_type, tree gnu_expr)
{
  /* Do not convert if the object's type is unconstrained because this would
     generate useless evaluations of the CONSTRUCTOR to compute the size.  */
  if (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE
      || CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_type)))
    return false;

  /* Do not convert if the object's type is a padding record whose field is of
     self-referential size because we want to copy only the actual data.  */
  if (type_is_padding_self_referential (gnu_type))
    return false;

  /* Do not convert a call to a function that returns with variable size since
     we want to use the return slot optimization in this case.  */
  if (TREE_CODE (gnu_expr) == CALL_EXPR
      && return_type_with_variable_size_p (TREE_TYPE (gnu_expr)))
    return false;

  /* Do not convert to a record type with a variant part from a record type
     without one, to keep the object simpler.  */
  if (TREE_CODE (gnu_type) == RECORD_TYPE
      && TREE_CODE (TREE_TYPE (gnu_expr)) == RECORD_TYPE
      && get_variant_part (gnu_type)
      && !get_variant_part (TREE_TYPE (gnu_expr)))
    return false;

  /* In all the other cases, convert the expression to the object's type.  */
  return true;
}
\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 to avoid Constraint_Error in static expressions
           are needed until after the front stops generating bogus
           conversions on bounds of real types.  */
        if (!Raises_Constraint_Error (gnat_lb))
          elaborate_expression (gnat_lb, gnat_entity, "L", true, false,
                                Needs_Debug_Info (gnat_entity));
        if (!Raises_Constraint_Error (gnat_hb))
          elaborate_expression (gnat_hb, gnat_entity, "U", true, false,
                                Needs_Debug_Info (gnat_entity));
      break;
      }

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

          for (gnat_field
               = First_Discriminant (Implementation_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))
            /* Ignore access discriminants.  */
            if (!Is_Access_Type (Etype (Node (gnat_discriminant_expr))))
              elaborate_expression (Node (gnat_discriminant_expr),
                                    gnat_entity, get_entity_char (gnat_field),
                                    true, false, false);
        }
      break;

    }
}
\f
/* Prepend to ATTR_LIST an entry for an attribute with provided TYPE,
   NAME, ARGS and ERROR_POINT.  */

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

  attr->type = attrib_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 an entry for an attribute provided by GNAT_PRAGMA.  */

static void
prepend_one_attribute_pragma (struct attrib **attr_list, Node_Id gnat_pragma)
{
  const Node_Id gnat_arg = Pragma_Argument_Associations (gnat_pragma);
  tree gnu_arg0 = NULL_TREE, gnu_arg1 = NULL_TREE;
  enum attrib_type etype;

  /* Map the pragma at hand.  Skip if this isn't one we know how to handle.  */
  switch (Get_Pragma_Id (Chars (Pragma_Identifier (gnat_pragma))))
    {
    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;

    case Pragma_Thread_Local_Storage:
      etype = ATTR_THREAD_LOCAL_STORAGE;
      break;

    default:
      return;
    }

  /* See what arguments we have and turn them into GCC trees for attribute
     handlers.  These expect identifier for strings.  We handle at most two
     arguments and static expressions only.  */
  if (Present (gnat_arg) && Present (First (gnat_arg)))
    {
      Node_Id gnat_arg0 = Next (First (gnat_arg));
      Node_Id gnat_arg1 = Empty;

      if (Present (gnat_arg0)
          && Is_OK_Static_Expression (Expression (gnat_arg0)))
        {
          gnu_arg0 = gnat_to_gnu (Expression (gnat_arg0));

          if (TREE_CODE (gnu_arg0) == STRING_CST)
            {
              gnu_arg0 = get_identifier (TREE_STRING_POINTER (gnu_arg0));
              if (IDENTIFIER_LENGTH (gnu_arg0) == 0)
                return;
            }

          gnat_arg1 = Next (gnat_arg0);
        }

      if (Present (gnat_arg1)
          && Is_OK_Static_Expression (Expression (gnat_arg1)))
        {
          gnu_arg1 = gnat_to_gnu (Expression (gnat_arg1));

          if (TREE_CODE (gnu_arg1) == STRING_CST)
           gnu_arg1 = get_identifier (TREE_STRING_POINTER (gnu_arg1));
        }
    }

  /* Prepend to the list.  Make a list of the argument we might have, as GCC
     expects it.  */
  prepend_one_attribute (attr_list, etype, gnu_arg0,
                         gnu_arg1
                         ? build_tree_list (NULL_TREE, gnu_arg1) : NULL_TREE,
                         Present (Next (First (gnat_arg)))
                         ? Expression (Next (First (gnat_arg))) : gnat_pragma);
}

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

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

  /* Attributes are stored as Representation Item pragmas.  */
  for (gnat_temp = First_Rep_Item (gnat_entity);
       Present (gnat_temp);
       gnat_temp = Next_Rep_Item (gnat_temp))
    if (Nkind (gnat_temp) == N_Pragma)
      prepend_one_attribute_pragma (attr_list, gnat_temp);
}
\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.  S is the suffix to use
   if a variable needs to be created and DEFINITION is true if this is done
   for a definition of GNAT_ENTITY.  If NEED_VALUE is true, we need a result;
   otherwise, we are just elaborating the expression for side-effects.  If
   NEED_DEBUG is true, we need a variable for debugging purposes even if it
   isn't needed for code generation.  */

static tree
elaborate_expression (Node_Id gnat_expr, Entity_Id gnat_entity, const char *s,
                      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.  */
  if (!need_value
      && (Is_OK_Static_Expression (gnat_expr)
          || (Nkind (gnat_expr) == N_Identifier
              && Ekind (Entity (gnat_expr)) == E_Discriminant)))
    return NULL_TREE;

  /* If it's a static expression, we don't need a variable for debugging.  */
  if (need_debug && Is_OK_Static_Expression (gnat_expr))
    need_debug = false;

  /* Otherwise, convert this tree to its GCC equivalent and elaborate it.  */
  gnu_expr = elaborate_expression_1 (gnat_to_gnu (gnat_expr), gnat_entity, s,
                                     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 and always return a result.  */

static tree
elaborate_expression_1 (tree gnu_expr, Entity_Id gnat_entity, const char *s,
                        bool definition, bool need_debug)
{
  const bool expr_public_p = Is_Public (gnat_entity);
  const bool expr_global_p = expr_public_p || global_bindings_p ();
  bool expr_variable_p, use_variable;

  /* If GNU_EXPR contains a placeholder, just return it.  We rely on the fact
     that an expression cannot contain both a discriminant and a variable.  */
  if (CONTAINS_PLACEHOLDER_P (gnu_expr))
    return gnu_expr;

  /* If GNU_EXPR is neither a constant nor based on a read-only variable, make
     a variable that is initialized to contain the expression when the package
     containing the definition is elaborated.  If this entity is defined at top
     level, replace the expression by the variable; otherwise use a SAVE_EXPR
     if this is necessary.  */
  if (TREE_CONSTANT (gnu_expr))
    expr_variable_p = false;
  else
    {
      /* Skip any conversions and simple constant arithmetics to see if the
         expression is based on a read-only variable.  */
      tree inner = remove_conversions (gnu_expr, true);

      inner = skip_simple_constant_arithmetic (inner);

      if (handled_component_p (inner))
        inner = get_inner_constant_reference (inner);

      expr_variable_p
        = !(inner
            && TREE_CODE (inner) == VAR_DECL
            && (TREE_READONLY (inner) || DECL_READONLY_ONCE_ELAB (inner)));
    }

  /* We only need to use the variable if we are in a global context since GCC
     can do the right thing in the local case.  However, when not optimizing,
     use it for bounds of loop iteration scheme to avoid code duplication.  */
  use_variable = expr_variable_p
                 && (expr_global_p
                     || (!optimize
                         && definition
                         && Is_Itype (gnat_entity)
                         && Nkind (Associated_Node_For_Itype (gnat_entity))
                            == N_Loop_Parameter_Specification));

  /* Now create it, possibly only for debugging purposes.  */
  if (use_variable || need_debug)
    {
      /* The following variable creation can happen when processing the body
         of subprograms that are defined out of the extended main unit and
         inlined.  In this case, we are not at the global scope, and thus the
         new variable must not be tagged "external", as we used to do here as
         soon as DEFINITION was false.  */
      tree gnu_decl
        = create_var_decl (create_concat_name (gnat_entity, s), NULL_TREE,
                           TREE_TYPE (gnu_expr), gnu_expr, true,
                           expr_public_p, !definition && expr_global_p,
                           expr_global_p, false, true, need_debug,
                           NULL, gnat_entity);

      /* Using this variable at debug time (if need_debug is true) requires a
         proper location.  The back-end will compute a location for this
         variable only if the variable is used by the generated code.
         Returning the variable ensures the caller will use it in generated
         code.  Note that there is no need for a location if the debug info
         contains an integer constant.
         TODO: when the encoding-based debug scheme is dropped, move this
         condition to the top-level IF block: we will not need to create a
         variable anymore in such cases, then.  */
      if (use_variable || (need_debug && !TREE_CONSTANT (gnu_expr)))
        return gnu_decl;
    }

  return expr_variable_p ? gnat_save_expr (gnu_expr) : gnu_expr;
}

/* Similar, but take an alignment factor and make it explicit in the tree.  */

static tree
elaborate_expression_2 (tree gnu_expr, Entity_Id gnat_entity, const char *s,
                        bool definition, bool need_debug, unsigned int align)
{
  tree unit_align = size_int (align / BITS_PER_UNIT);
  return
    size_binop (MULT_EXPR,
                elaborate_expression_1 (size_binop (EXACT_DIV_EXPR,
                                                    gnu_expr,
                                                    unit_align),
                                        gnat_entity, s, definition,
                                        need_debug),
                unit_align);
}

/* Structure to hold internal data for elaborate_reference.  */

struct er_data
{
  Entity_Id entity;
  bool definition;
  unsigned int n;
};

/* Wrapper function around elaborate_expression_1 for elaborate_reference.  */

static tree
elaborate_reference_1 (tree ref, void *data)
{
  struct er_data *er = (struct er_data *)data;
  char suffix[16];

  /* This is what elaborate_expression_1 does if NEED_DEBUG is false.  */
  if (TREE_CONSTANT (ref))
    return ref;

  /* If this is a COMPONENT_REF of a fat pointer, elaborate the entire fat
     pointer.  This may be more efficient, but will also allow us to more
     easily find the match for the PLACEHOLDER_EXPR.  */
  if (TREE_CODE (ref) == COMPONENT_REF
      && TYPE_IS_FAT_POINTER_P (TREE_TYPE (TREE_OPERAND (ref, 0))))
    return build3 (COMPONENT_REF, TREE_TYPE (ref),
                   elaborate_reference_1 (TREE_OPERAND (ref, 0), data),
                   TREE_OPERAND (ref, 1), NULL_TREE);

  sprintf (suffix, "EXP%d", ++er->n);
  return
    elaborate_expression_1 (ref, er->entity, suffix, er->definition, false);
}

/* Elaborate the reference REF to be used as renamed object for GNAT_ENTITY.
   DEFINITION is true if this is done for a definition of GNAT_ENTITY and
   INIT is set to the first arm of a COMPOUND_EXPR present in REF, if any.  */

static tree
elaborate_reference (tree ref, Entity_Id gnat_entity, bool definition,
                     tree *init)
{
  struct er_data er = { gnat_entity, definition, 0 };
  return gnat_rewrite_reference (ref, elaborate_reference_1, &er, init);
}
\f
/* Given a GNU tree and a GNAT list of choices, generate an expression to test
   the value passed against the list of choices.  */

static tree
choices_to_gnu (tree operand, Node_Id choices)
{
  Node_Id choice;
  Node_Id gnat_temp;
  tree result = boolean_false_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));

          this_test
            = build_binary_op (TRUTH_ANDIF_EXPR, boolean_type_node,
                               build_binary_op (GE_EXPR, boolean_type_node,
                                                operand, low, true),
                               build_binary_op (LE_EXPR, boolean_type_node,
                                                operand, high, true),
                               true);

          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, boolean_type_node,
                               build_binary_op (GE_EXPR, boolean_type_node,
                                                operand, low, true),
                               build_binary_op (LE_EXPR, boolean_type_node,
                                                operand, high, true),
                               true);
          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, boolean_type_node,
                                   build_binary_op (GE_EXPR, boolean_type_node,
                                                    operand, low, true),
                                   build_binary_op (LE_EXPR, boolean_type_node,
                                                    operand, high, true),
                                   true);
              break;
            }

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

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

        case N_Others_Choice:
          this_test = boolean_true_node;
          break;

        default:
          gcc_unreachable ();
        }

      if (result == boolean_false_node)
        result = this_test;
      else
        result = build_binary_op (TRUTH_ORIF_EXPR, boolean_type_node, result,
                                  this_test, true);
    }

  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 (type_has_variable_size (field_type))
    return 0;

  /* In the other cases, we can honor the packing.  */
  if (packed)
    return packed;

  /* If the alignment of the record is specified and the field type
     is over-aligned, request Storage_Unit alignment for the field.  */
  if (TYPE_ALIGN (record_type)
      && TYPE_ALIGN (field_type) > TYPE_ALIGN (record_type))
    return -1;

  /* Likewise if the maximum alignment of the record is specified.  */
  if (TYPE_MAX_ALIGN (record_type)
      && TYPE_ALIGN (field_type) > TYPE_MAX_ALIGN (record_type))
    return -1;

  return 0;
}

/* 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 or -1 if the enclosing
   record has Component_Alignment of Storage_Unit.

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

   DEBUG_INFO_P is true if we need to write debug information for types
   that we may create in the process.  */

static tree
gnat_to_gnu_field (Entity_Id gnat_field, tree gnu_record_type, int packed,
                   bool definition, bool debug_info_p)
{
  const Entity_Id gnat_record_type = Underlying_Type (Scope (gnat_field));
  const Entity_Id gnat_field_type = Etype (gnat_field);
  const bool is_atomic
    = (Is_Atomic_Or_VFA (gnat_field) || Is_Atomic_Or_VFA (gnat_field_type));
  const bool is_aliased = Is_Aliased (gnat_field);
  const bool is_independent
    = (Is_Independent (gnat_field) || Is_Independent (gnat_field_type));
  const bool is_volatile
    = (Treat_As_Volatile (gnat_field) || Treat_As_Volatile (gnat_field_type));
  const bool is_strict_alignment = Strict_Alignment (gnat_field_type);
  /* We used to consider that volatile fields also require strict alignment,
     but that was an interpolation and would cause us to reject a pragma
     volatile on a packed record type containing boolean components, while
     there is no basis to do so in the RM.  In such cases, the writes will
     involve load-modify-store sequences, but that's OK for volatile.  The
     only constraint is the implementation advice whereby only the bits of
     the components should be accessed if they both start and end on byte
     boundaries, but that should be guaranteed by the GCC memory model.  */
  const bool needs_strict_alignment
    = (is_atomic || is_aliased || is_independent || is_strict_alignment);
  tree gnu_field_type = gnat_to_gnu_type (gnat_field_type);
  tree gnu_field_id = get_entity_name (gnat_field);
  tree gnu_field, gnu_size, gnu_pos;

  /* 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_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 (gnat_field_type), gnu_field_type,
                              gnat_field, FIELD_DECL, false, true);
  else
    gnu_size = NULL_TREE;

  /* If we have a specified size that is smaller than that of the field's type,
     or a position is specified, and the field's type is a record that doesn't
     require strict alignment, 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.

     Changing to an integral mode form is useful when the record is packed as
     we can 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 access
     to the field, because GCC cannot handle non-byte-aligned BLKmode fields.

     Changing to a smaller form is required if the specified size is smaller
     than that of the field's type and the type contains sub-fields that are
     padded, in order to avoid generating accesses to these sub-fields that
     are wider than the field.

     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.  */
  if (!needs_strict_alignment
      && RECORD_OR_UNION_TYPE_P (gnu_field_type)
      && !TYPE_FAT_POINTER_P (gnu_field_type)
      && tree_fits_uhwi_p (TYPE_SIZE (gnu_field_type))
      && (packed == 1
          || (gnu_size
              && (tree_int_cst_lt (gnu_size, TYPE_SIZE (gnu_field_type))
                  || (Present (Component_Clause (gnat_field))
                      && !(UI_To_Int (Component_Bit_Offset (gnat_field))
                           % BITS_PER_UNIT == 0
                           && value_factor_p (gnu_size, BITS_PER_UNIT)))))))
    {
      tree gnu_packable_type = make_packable_type (gnu_field_type, true);
      if (gnu_packable_type != gnu_field_type)
        {
          gnu_field_type = gnu_packable_type;
          if (!gnu_size)
            gnu_size = rm_size (gnu_field_type);
        }
    }

  if (Is_Atomic_Or_VFA (gnat_field))
    check_ok_for_atomic_type (gnu_field_type, gnat_field, false);

  if (Present (Component_Clause (gnat_field)))
    {
      Node_Id gnat_clause = Component_Clause (gnat_field);
      Entity_Id gnat_parent = Parent_Subtype (gnat_record_type);

      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.  This test is omitted if the parent of the tagged type has a
         full rep clause since, in this case, component clauses are allowed to
         overlay the space allocated for the parent type and the front-end has
         checked that there are no overlapping components.  */
      if (Present (gnat_parent) && !Is_Fully_Repped_Tagged_Type (gnat_parent))
        {
          tree gnu_parent = gnat_to_gnu_type (gnat_parent);

          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 ^}",
               Position (gnat_clause), gnat_field, TYPE_SIZE_UNIT (gnu_parent));
        }

      /* If this field needs strict alignment, make sure that the record is
         sufficiently aligned and that the position and size are consistent
         with the type.  But don't do it if we are just annotating types and
         the field's type is tagged, since tagged types aren't fully laid out
         in this mode.  Also, note that atomic implies volatile so the inner
         test sequences ordering is significant here.  */
      if (needs_strict_alignment
          && !(type_annotate_only && Is_Tagged_Type (gnat_field_type)))
        {
          const unsigned int type_align = TYPE_ALIGN (gnu_field_type);

          if (TYPE_ALIGN (gnu_record_type) < type_align)
            SET_TYPE_ALIGN (gnu_record_type, type_align);

          /* If the position is not a multiple of the alignment of the type,
             then error out and reset the position.  */
          if (!integer_zerop (size_binop (TRUNC_MOD_EXPR, gnu_pos,
                                          bitsize_int (type_align))))
            {
              const char *s;

              if (is_atomic)
                s = "position of atomic field& must be multiple of ^ bits";
              else if (is_aliased)
                s = "position of aliased field& must be multiple of ^ bits";
              else if (is_independent)
                s = "position of independent field& must be multiple of ^ bits";
              else if (is_strict_alignment)
                s = "position of & with aliased or tagged part must be"
                    " multiple of ^ bits";
              else
                gcc_unreachable ();

              post_error_ne_num (s, First_Bit (gnat_clause), gnat_field,
                                 type_align);
              gnu_pos = NULL_TREE;
            }

          if (gnu_size)
            {
              tree gnu_type_size = TYPE_SIZE (gnu_field_type);
              const int cmp = tree_int_cst_compare (gnu_size, gnu_type_size);

              /* If the size is lower than that of the type, or greater for
                 atomic and aliased, then error out and reset the size.  */
              if (cmp < 0 || (cmp > 0 && (is_atomic || is_aliased)))
                {
                  const char *s;

                  if (is_atomic)
                    s = "size of atomic field& must be ^ bits";
                  else if (is_aliased)
                    s = "size of aliased field& must be ^ bits";
                  else if (is_independent)
                    s = "size of independent field& must be at least ^ bits";
                  else if (is_strict_alignment)
                    s = "size of & with aliased or tagged part must be"
                        " at least ^ bits";
                  else
                    gcc_unreachable ();

                  post_error_ne_tree (s, Last_Bit (gnat_clause), gnat_field,
                                      gnu_type_size);
                  gnu_size = NULL_TREE;
                }

              /* Likewise if the size is not a multiple of a byte,  */
              else if (!integer_zerop (size_binop (TRUNC_MOD_EXPR, gnu_size,
                                                   bitsize_unit_node)))
                {
                  const char *s;

                  if (is_independent)
                    s = "size of independent field& must be multiple of"
                        " Storage_Unit";
                  else if (is_strict_alignment)
                    s = "size of & with aliased or tagged part must be"
                        " multiple of Storage_Unit";
                  else
                    gcc_unreachable ();

                  post_error_ne (s, Last_Bit (gnat_clause), gnat_field);
                  gnu_size = NULL_TREE;
                }
            }
        }
    }

  /* 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 (gnat_record_type)
           && Chars (gnat_field) == Name_uTag)
    {
      gnu_pos = bitsize_zero_node;
      gnu_size = TYPE_SIZE (gnu_field_type);
    }

  else
    {
      gnu_pos = NULL_TREE;

      /* 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);
    }

  /* 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 (gnat_field_type)))
    {
      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)
    {
      tree orig_field_type;

      /* 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, if it has the same storage order as the enclosing record
         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)
          && TYPE_REVERSE_STORAGE_ORDER (gnu_field_type)
             == Reverse_Storage_Order (gnat_record_type)
          && tree_int_cst_compare (gnu_size, TYPE_ADA_SIZE (gnu_field_type))
               <= 0)
        gnu_field_type = TREE_TYPE (TYPE_FIELDS (gnu_field_type));

      /* Similarly if the field's type is a misaligned integral type, but
         there is no restriction on the size as there is no justification.  */
      if (!needs_strict_alignment
          && TYPE_IS_PADDING_P (gnu_field_type)
          && INTEGRAL_TYPE_P (TREE_TYPE (TYPE_FIELDS (gnu_field_type))))
        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));

      orig_field_type = gnu_field_type;
      gnu_field_type = maybe_pad_type (gnu_field_type, gnu_size, 0, gnat_field,
                                       false, 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_field_type != orig_field_type
          && !DECL_P (TYPE_NAME (gnu_field_type)))
        create_type_decl (TYPE_NAME (gnu_field_type), gnu_field_type, true,
                          debug_info_p, gnat_field);
    }

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

  /* If the field's type is a padded type made for a scalar field of a record
     type with reverse storage order, we need to propagate the reverse storage
     order to the padding type since it is the innermost enclosing aggregate
     type around the scalar.  */
  if (TYPE_IS_PADDING_P (gnu_field_type)
      && TYPE_REVERSE_STORAGE_ORDER (gnu_record_type)
      && Is_Scalar_Type (gnat_field_type))
    gnu_field_type = set_reverse_storage_order_on_pad_type (gnu_field_type);

  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,
                         gnu_size, gnu_pos, packed, is_aliased);
  Sloc_to_locus (Sloc (gnat_field), &DECL_SOURCE_LOCATION (gnu_field));
  DECL_ALIASED_P (gnu_field) = is_aliased;
  TREE_SIDE_EFFECTS (gnu_field) = TREE_THIS_VOLATILE (gnu_field) = is_volatile;

  if (Ekind (gnat_field) == E_Discriminant)
    {
      DECL_INVARIANT_P (gnu_field)
        = No (Discriminant_Default_Value (gnat_field));
      DECL_DISCRIMINANT_NUMBER (gnu_field)
        = UI_To_gnu (Discriminant_Number (gnat_field), sizetype);
    }

  return gnu_field;
}
\f
/* Return true if at least one member of COMPONENT_LIST needs strict
   alignment.  */

static bool
components_need_strict_alignment (Node_Id component_list)
{
  Node_Id component_decl;

  for (component_decl = First_Non_Pragma (Component_Items (component_list));
       Present (component_decl);
       component_decl = Next_Non_Pragma (component_decl))
    {
      Entity_Id gnat_field = Defining_Entity (component_decl);

      if (Is_Aliased (gnat_field))
        return true;

      if (Strict_Alignment (Etype (gnat_field)))
        return true;
    }

  return false;
}

/* Return true if TYPE is a type with variable size or a padding type with a
   field of variable size or a record that has a field with such a type.  */

static bool
type_has_variable_size (tree type)
{
  tree field;

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

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

  if (!RECORD_OR_UNION_TYPE_P (type))
    return false;

  for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
    if (type_has_variable_size (TREE_TYPE (field)))
      return true;

  return false;
}
\f
/* Return true if FIELD is an artificial field.  */

static bool
field_is_artificial (tree field)
{
  /* These fields are generated by the front-end proper.  */
  if (IDENTIFIER_POINTER (DECL_NAME (field)) [0] == '_')
    return true;

  /* These fields are generated by gigi.  */
  if (DECL_INTERNAL_P (field))
    return true;

  return false;
}

/* Return true if FIELD is a non-artificial field with self-referential
   size.  */

static bool
field_has_self_size (tree field)
{
  if (field_is_artificial (field))
    return false;

  if (DECL_SIZE (field) && TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
    return false;

  return CONTAINS_PLACEHOLDER_P (TYPE_SIZE (TREE_TYPE (field)));
}

/* Return true if FIELD is a non-artificial field with variable size.  */

static bool
field_has_variable_size (tree field)
{
  if (field_is_artificial (field))
    return false;

  if (DECL_SIZE (field) && TREE_CODE (DECL_SIZE (field)) == INTEGER_CST)
    return false;

  return TREE_CODE (TYPE_SIZE (TREE_TYPE (field))) != INTEGER_CST;
}

/* 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));
}

/* Reverse function from gnat_to_gnu_field: return the GNAT field present in
   either GNAT_COMPONENT_LIST or the discriminants of GNAT_RECORD_TYPE, and
   corresponding to the GNU tree GNU_FIELD.  */

static Entity_Id
gnu_field_to_gnat (tree gnu_field, Node_Id gnat_component_list,
                   Entity_Id gnat_record_type)
{
  Entity_Id gnat_component_decl, gnat_field;

  if (Present (Component_Items (gnat_component_list)))
    for (gnat_component_decl
           = First_Non_Pragma (Component_Items (gnat_component_list));
         Present (gnat_component_decl);
         gnat_component_decl = Next_Non_Pragma (gnat_component_decl))
      {
        gnat_field = Defining_Entity (gnat_component_decl);
        if (gnat_to_gnu_field_decl (gnat_field) == gnu_field)
          return gnat_field;
      }

  if (Has_Discriminants (gnat_record_type))
    for (gnat_field = First_Stored_Discriminant (gnat_record_type);
         Present (gnat_field);
         gnat_field = Next_Stored_Discriminant (gnat_field))
      if (gnat_to_gnu_field_decl (gnat_field) == gnu_field)
        return gnat_field;

  return Empty;
}

/* Issue a warning for the problematic placement of GNU_FIELD present in
   either GNAT_COMPONENT_LIST or the discriminants of GNAT_RECORD_TYPE.
   IN_VARIANT is true if GNAT_COMPONENT_LIST is the list of a variant.
   DO_REORDER is true if fields of GNAT_RECORD_TYPE are being reordered.  */

static void
warn_on_field_placement (tree gnu_field, Node_Id gnat_component_list,
                         Entity_Id gnat_record_type, bool in_variant,
                         bool do_reorder)
{
  const char *msg1
    = in_variant
      ? "?variant layout may cause performance issues"
      : "?record layout may cause performance issues";
  const char *msg2
    = field_has_self_size (gnu_field)
      ? "?component & whose length depends on a discriminant"
      : field_has_variable_size (gnu_field)
        ? "?component & whose length is not fixed"
        : "?component & whose length is not multiple of a byte";
  const char *msg3
    = do_reorder
      ? "?comes too early and was moved down"
      : "?comes too early and ought to be moved down";
  Entity_Id gnat_field
    = gnu_field_to_gnat (gnu_field, gnat_component_list, gnat_record_type);

  gcc_assert (Present (gnat_field));

  post_error (msg1, gnat_field);
  post_error_ne (msg2, gnat_field, gnat_field);
  post_error (msg3, gnat_field);
}

/* Structure holding information for a given variant.  */
typedef struct vinfo
{
  /* The record type of the variant.  */
  tree type;

  /* The name of the variant.  */
  tree name;

  /* The qualifier of the variant.  */
  tree qual;

  /* Whether the variant has a rep clause.  */
  bool has_rep;

  /* Whether the variant is packed.  */
  bool packed;

} vinfo_t;

/* Translate and chain GNAT_COMPONENT_LIST present in GNAT_RECORD_TYPE to
   GNU_FIELD_LIST, set the result as the field list of GNU_RECORD_TYPE and
   finish it up.  Return true if GNU_RECORD_TYPE has a rep clause that affects
   the layout (see below).  When called from gnat_to_gnu_entity during the
   processing of a record definition, the GCC node for the parent, if any,
   will be the single field of GNU_RECORD_TYPE and the GCC nodes for the
   discriminants will be on GNU_FIELD_LIST.  The other call to this function
   is a recursive call for the component list of a variant and, in this case,
   GNU_FIELD_LIST is empty.

   PACKED is 1 if this is for a packed record or -1 if this is for a record
   with Component_Alignment of Storage_Unit.

   DEFINITION is true if we are defining this record type.

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

   ALL_REP is true if a rep clause is present for all the fields.

   UNCHECKED_UNION is true if we are building this type for a record with a
   Pragma Unchecked_Union.

   ARTIFICIAL is true if this is a type that was generated by the compiler.

   DEBUG_INFO is true if we need to write debug information about the type.

   MAYBE_UNUSED is true if this type may be unused in the end; this doesn't
   mean that its contents may be unused as well, only the container itself.

   FIRST_FREE_POS, if nonzero, is the first (lowest) free field position in
   the outer record type down to this variant level.  It is nonzero only if
   all the fields down to this level have a rep clause and ALL_REP is false.

   P_GNU_REP_LIST, if nonzero, is a pointer to a list to which each field
   with a rep clause is to be added; in this case, that is all that should
   be done with such fields and the return value will be false.  */

static bool
components_to_record (Node_Id gnat_component_list, Entity_Id gnat_record_type,
                      tree gnu_field_list, tree gnu_record_type, int packed,
                      bool definition, bool cancel_alignment, bool all_rep,
                      bool unchecked_union, bool artificial, bool debug_info,
                      bool maybe_unused, tree first_free_pos,
                      tree *p_gnu_rep_list)
{
  const bool needs_xv_encodings
    = debug_info && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL;
  bool all_rep_and_size = all_rep && TYPE_SIZE (gnu_record_type);
  bool variants_have_rep = all_rep;
  bool layout_with_rep = false;
  bool has_self_field = false;
  bool has_aliased_after_self_field = false;
  Entity_Id gnat_component_decl, gnat_variant_part;
  tree gnu_field, gnu_next, gnu_last;
  tree gnu_variant_part = NULL_TREE;
  tree gnu_rep_list = NULL_TREE;

  /* For each component referenced in a component declaration create a GCC
     field and add it to the list, skipping pragmas in the GNAT list.  */
  gnu_last = tree_last (gnu_field_list);
  if (Present (Component_Items (gnat_component_list)))
    for (gnat_component_decl
           = First_Non_Pragma (Component_Items (gnat_component_list));
         Present (gnat_component_decl);
         gnat_component_decl = Next_Non_Pragma (gnat_component_decl))
      {
        Entity_Id gnat_field = Defining_Entity (gnat_component_decl);
        Name_Id gnat_name = Chars (gnat_field);

        /* If present, the _Parent field must have been created as the single
           field of the record type.  Put it before any other fields.  */
        if (gnat_name == Name_uParent)
          {
            gnu_field = TYPE_FIELDS (gnu_record_type);
            gnu_field_list = chainon (gnu_field_list, gnu_field);
          }
        else
          {
            gnu_field = gnat_to_gnu_field (gnat_field, gnu_record_type, packed,
                                           definition, debug_info);

            /* If this is the _Tag field, put it before any other fields.  */
            if (gnat_name == Name_uTag)
              gnu_field_list = chainon (gnu_field_list, gnu_field);

            /* If this is the _Controller field, put it before the other
               fields except for the _Tag or _Parent field.  */
            else if (gnat_name == Name_uController && gnu_last)
              {
                DECL_CHAIN (gnu_field) = DECL_CHAIN (gnu_last);
                DECL_CHAIN (gnu_last) = gnu_field;
              }

            /* If this is a regular field, put it after the other fields.  */
            else
              {
                DECL_CHAIN (gnu_field) = gnu_field_list;
                gnu_field_list = gnu_field;
                if (!gnu_last)
                  gnu_last = gnu_field;

                /* And record information for the final layout.  */
                if (field_has_self_size (gnu_field))
                  has_self_field = true;
                else if (has_self_field && DECL_ALIASED_P (gnu_field))
                  has_aliased_after_self_field = true;
              }
          }

        save_gnu_tree (gnat_field, gnu_field, false);
      }

  /* At the end of the component list there may be a variant part.  */
  gnat_variant_part = Variant_Part (gnat_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 (gnat_variant_part))
    {
      Node_Id gnat_discr = Name (gnat_variant_part), variant;
      tree gnu_discr = gnat_to_gnu (gnat_discr);
      tree gnu_name = TYPE_IDENTIFIER (gnu_record_type);
      tree gnu_var_name
        = concat_name (get_identifier (Get_Name_String (Chars (gnat_discr))),
                       "XVN");
      tree gnu_union_type, gnu_union_name;
      tree this_first_free_pos, gnu_variant_list = NULL_TREE;
      bool union_field_needs_strict_alignment = false;
      auto_vec <vinfo_t, 16> variant_types;
      vinfo_t *gnu_variant;
      unsigned int variants_align = 0;
      unsigned int i;

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

      /* Reuse the enclosing union if this is an Unchecked_Union whose fields
         are all in the variant part, to match the layout of C unions.  There
         is an associated check below.  */
      if (TREE_CODE (gnu_record_type) == UNION_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;
          SET_TYPE_ALIGN (gnu_union_type, 0);
          TYPE_PACKED (gnu_union_type) = TYPE_PACKED (gnu_record_type);
          TYPE_REVERSE_STORAGE_ORDER (gnu_union_type)
            = TYPE_REVERSE_STORAGE_ORDER (gnu_record_type);
        }

      /* If all the fields down to this level have a rep clause, find out
         whether all the fields at this level also have one.  If so, then
         compute the new first free position to be passed downward.  */
      this_first_free_pos = first_free_pos;
      if (this_first_free_pos)
        {
          for (gnu_field = gnu_field_list;
               gnu_field;
               gnu_field = DECL_CHAIN (gnu_field))
            if (DECL_FIELD_OFFSET (gnu_field))
              {
                tree pos = bit_position (gnu_field);
                if (!tree_int_cst_lt (pos, this_first_free_pos))
                  this_first_free_pos
                    = size_binop (PLUS_EXPR, pos, DECL_SIZE (gnu_field));
              }
            else
              {
                this_first_free_pos = NULL_TREE;
                break;
              }
        }

      /* We build the variants in two passes.  The bulk of the work is done in
         the first pass, that is to say translating the GNAT nodes, building
         the container types and computing the associated properties.  However
         we cannot finish up the container types during this pass because we
         don't know where the variant part will be placed until the end.  */
      for (variant = First_Non_Pragma (Variants (gnat_variant_part));
           Present (variant);
           variant = Next_Non_Pragma (variant))
        {
          tree gnu_variant_type = make_node (RECORD_TYPE);
          tree gnu_inner_name, gnu_qual;
          bool has_rep;
          int field_packed;
          vinfo_t vinfo;

          Get_Variant_Encoding (variant);
          gnu_inner_name = get_identifier_with_length (Name_Buffer, Name_Len);
          TYPE_NAME (gnu_variant_type)
            = concat_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.  */
          SET_TYPE_ALIGN (gnu_variant_type, TYPE_ALIGN (gnu_record_type));
          TYPE_PACKED (gnu_variant_type) = TYPE_PACKED (gnu_record_type);
          TYPE_REVERSE_STORAGE_ORDER (gnu_variant_type)
            = TYPE_REVERSE_STORAGE_ORDER (gnu_record_type);

          /* Similarly, if the outer record has a size specified and all
             the fields have a rep clause, we can propagate the size.  */
          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);
            }

          /* Add the fields into the record type for the variant.  Note that
             we aren't sure to really use it at this point, see below.  */
          has_rep
            = components_to_record (Component_List (variant), gnat_record_type,
                                    NULL_TREE, gnu_variant_type, packed,
                                    definition, !all_rep_and_size, all_rep,
                                    unchecked_union, true, needs_xv_encodings,
                                    true, this_first_free_pos,
                                    all_rep || this_first_free_pos
                                    ? NULL : &gnu_rep_list);

          /* Translate the qualifier and annotate the GNAT node.  */
          gnu_qual = choices_to_gnu (gnu_discr, Discrete_Choices (variant));
          Set_Present_Expr (variant, annotate_value (gnu_qual));

          /* Deal with packedness like in gnat_to_gnu_field.  */
          if (components_need_strict_alignment (Component_List (variant)))
            {
              field_packed = 0;
              union_field_needs_strict_alignment = true;
            }
          else
            field_packed
              = adjust_packed (gnu_variant_type, gnu_record_type, packed);

          /* Push this variant onto the stack for the second pass.  */
          vinfo.type = gnu_variant_type;
          vinfo.name = gnu_inner_name;
          vinfo.qual = gnu_qual;
          vinfo.has_rep = has_rep;
          vinfo.packed = field_packed;
          variant_types.safe_push (vinfo);

          /* Compute the global properties that will determine the placement of
             the variant part.  */
          variants_have_rep |= has_rep;
          if (!field_packed && TYPE_ALIGN (gnu_variant_type) > variants_align)
            variants_align = TYPE_ALIGN (gnu_variant_type);
        }

      /* Round up the first free position to the alignment of the variant part
         for the variants without rep clause.  This will guarantee a consistent
         layout independently of the placement of the variant part.  */
      if (variants_have_rep && variants_align > 0 && this_first_free_pos)
        this_first_free_pos = round_up (this_first_free_pos, variants_align);

      /* In the second pass, the container types are adjusted if necessary and
         finished up, then the corresponding fields of the variant part are
         built with their qualifier, unless this is an unchecked union.  */
      FOR_EACH_VEC_ELT (variant_types, i, gnu_variant)
        {
          tree gnu_variant_type = gnu_variant->type;
          tree gnu_field_list = TYPE_FIELDS (gnu_variant_type);

          /* If this is an Unchecked_Union whose fields are all in the variant
             part and we have a single field with no representation clause or
             placed at offset zero, use the field directly to match the layout
             of C unions.  */
          if (TREE_CODE (gnu_record_type) == UNION_TYPE
              && gnu_field_list
              && !DECL_CHAIN (gnu_field_list)
              && (!DECL_FIELD_OFFSET (gnu_field_list)
                  || integer_zerop (bit_position (gnu_field_list))))
            {
              gnu_field = gnu_field_list;
              DECL_CONTEXT (gnu_field) = gnu_record_type;
            }
          else
            {
              /* Finalize the variant type now.  We used to throw away empty
                 record types 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.  */
              if (gnu_field_list && variants_have_rep && !gnu_variant->has_rep)
                {
                  /* The variant part will be at offset 0 so we need to ensure
                     that the fields are laid out starting from the first free
                     position at this level.  */
                  tree gnu_rep_type = make_node (RECORD_TYPE);
                  tree gnu_rep_part;
                  TYPE_REVERSE_STORAGE_ORDER (gnu_rep_type)
                    = TYPE_REVERSE_STORAGE_ORDER (gnu_variant_type);
                  finish_record_type (gnu_rep_type, NULL_TREE, 0, debug_info);
                  gnu_rep_part
                    = create_rep_part (gnu_rep_type, gnu_variant_type,
                                       this_first_free_pos);
                  DECL_CHAIN (gnu_rep_part) = gnu_field_list;
                  gnu_field_list = gnu_rep_part;
                  finish_record_type (gnu_variant_type, gnu_field_list, 0,
                                      false);
                }

              if (debug_info)
                rest_of_record_type_compilation (gnu_variant_type);
              create_type_decl (TYPE_NAME (gnu_variant_type), gnu_variant_type,
                                true, needs_xv_encodings, gnat_component_list);

              gnu_field
                = create_field_decl (gnu_variant->name, gnu_variant_type,
                                     gnu_union_type,
                                     all_rep_and_size
                                     ? TYPE_SIZE (gnu_variant_type) : 0,
                                     variants_have_rep ? bitsize_zero_node : 0,
                                     gnu_variant->packed, 0);

              DECL_INTERNAL_P (gnu_field) = 1;

              if (!unchecked_union)
                DECL_QUALIFIER (gnu_field) = gnu_variant->qual;
            }

          DECL_CHAIN (gnu_field) = gnu_variant_list;
          gnu_variant_list = gnu_field;
        }

      /* Only make the QUAL_UNION_TYPE if there are 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, needs_xv_encodings);

          /* 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_rep_list);
              return variants_have_rep;
            }

          create_type_decl (TYPE_NAME (gnu_union_type), gnu_union_type, true,
                            needs_xv_encodings, gnat_component_list);

          /* Deal with packedness like in gnat_to_gnu_field.  */
          if (union_field_needs_strict_alignment)
            union_field_packed = 0;
          else
            union_field_packed
              = adjust_packed (gnu_union_type, gnu_record_type, packed);

          gnu_variant_part
            = create_field_decl (gnu_var_name, gnu_union_type, gnu_record_type,
                                 all_rep_and_size
                                 ? TYPE_SIZE (gnu_union_type) : 0,
                                 variants_have_rep ? bitsize_zero_node : 0,
                                 union_field_packed, 0);

          DECL_INTERNAL_P (gnu_variant_part) = 1;
        }
    }

  /* Scan GNU_FIELD_LIST and see if any fields have rep clauses.  If they do,
     pull them out and put them onto the appropriate list.  We have to do it
     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.

     Similarly, pull out the fields with zero size and no rep clause, as they
     would otherwise modify the layout and thus very likely run afoul of the
     Ada semantics, which are different from those of C here.

     Finally, if there is an aliased field placed in the list after fields
     with self-referential size, pull out the latter in the same way.

     Optionally, if the reordering mechanism is enabled, pull out the fields
     with self-referential size, variable size and fixed size not a multiple
     of a byte, so that they don't cause the regular fields to be either at
     self-referential/variable offset or misaligned.  Note, in the latter
     case, that this can only happen in packed record types so the alignment
     is effectively capped to the byte for the whole record.

     Optionally, if the layout warning is enabled, keep track of the above 4
     different kinds of fields and issue a warning if some of them would be
     (or are being) reordered by the reordering mechanism.

     Finally, pull out the fields whose size is not a multiple of a byte, so
     that they don't cause the regular fields to be misaligned.  As this can
     only happen in packed record types, the alignment is capped to the byte.

     ??? If we reorder them, debugging information will be wrong but there is
     nothing that can be done about this at the moment.  */
  const bool do_reorder = OK_To_Reorder_Components (gnat_record_type);
  const bool w_reorder
    = Warn_On_Questionable_Layout
      && (Convention (gnat_record_type) == Convention_Ada);
  const bool in_variant = (p_gnu_rep_list != NULL);
  tree gnu_zero_list = NULL_TREE;
  tree gnu_self_list = NULL_TREE;
  tree gnu_var_list = NULL_TREE;
  tree gnu_bitp_list = NULL_TREE;
  tree gnu_tmp_bitp_list = NULL_TREE;
  unsigned int tmp_bitp_size = 0;
  unsigned int last_reorder_field_type = -1;
  unsigned int tmp_last_reorder_field_type = -1;

#define MOVE_FROM_FIELD_LIST_TO(LIST)   \
  do {                                  \
    if (gnu_last)                       \
      DECL_CHAIN (gnu_last) = gnu_next; \
    else                                \
      gnu_field_list = gnu_next;        \
                                        \
    DECL_CHAIN (gnu_field) = (LIST);    \
    (LIST) = gnu_field;                 \
  } while (0)

  gnu_last = NULL_TREE;
  for (gnu_field = gnu_field_list; gnu_field; gnu_field = gnu_next)
    {
      gnu_next = DECL_CHAIN (gnu_field);

      if (DECL_FIELD_OFFSET (gnu_field))
        {
          MOVE_FROM_FIELD_LIST_TO (gnu_rep_list);
          continue;
        }

      if (DECL_SIZE (gnu_field) && integer_zerop (DECL_SIZE (gnu_field)))
        {
          DECL_FIELD_OFFSET (gnu_field) = size_zero_node;
          SET_DECL_OFFSET_ALIGN (gnu_field, BIGGEST_ALIGNMENT);
          DECL_FIELD_BIT_OFFSET (gnu_field) = bitsize_zero_node;
          if (DECL_ALIASED_P (gnu_field))
            SET_TYPE_ALIGN (gnu_record_type,
                            MAX (TYPE_ALIGN (gnu_record_type),
                                 TYPE_ALIGN (TREE_TYPE (gnu_field))));
          MOVE_FROM_FIELD_LIST_TO (gnu_zero_list);
          continue;
        }

      if (has_aliased_after_self_field && field_has_self_size (gnu_field))
        {
          MOVE_FROM_FIELD_LIST_TO (gnu_self_list);
          continue;
        }

      /* We don't need further processing in default mode.  */
      if (!w_reorder && !do_reorder)
        {
          gnu_last = gnu_field;
          continue;
        }

      if (field_has_self_size (gnu_field))
        {
          if (w_reorder)
            {
              if (last_reorder_field_type < 4)
                warn_on_field_placement (gnu_field, gnat_component_list,
                                         gnat_record_type, in_variant,
                                         do_reorder);
              else
                last_reorder_field_type = 4;
            }

          if (do_reorder)
            {
              MOVE_FROM_FIELD_LIST_TO (gnu_self_list);
              continue;
            }
        }

      else if (field_has_variable_size (gnu_field))
        {
          if (w_reorder)
            {
              if (last_reorder_field_type < 3)
                warn_on_field_placement (gnu_field, gnat_component_list,
                                         gnat_record_type, in_variant,
                                         do_reorder);
              else
                last_reorder_field_type = 3;
            }

          if (do_reorder)
            {
              MOVE_FROM_FIELD_LIST_TO (gnu_var_list);
              continue;
            }
        }

      else
        {
          /* If the field has no size, then it cannot be bit-packed.  */
          const unsigned int bitp_size
            = DECL_SIZE (gnu_field)
              ? TREE_INT_CST_LOW (DECL_SIZE (gnu_field)) % BITS_PER_UNIT
              : 0;

          /* If the field is bit-packed, we move it to a temporary list that
             contains the contiguously preceding bit-packed fields, because
             we want to be able to put them back if the misalignment happens
             to cancel itself after several bit-packed fields.  */
          if (bitp_size != 0)
            {
              tmp_bitp_size = (tmp_bitp_size + bitp_size) % BITS_PER_UNIT;

              if (last_reorder_field_type != 2)
                {
                  tmp_last_reorder_field_type = last_reorder_field_type;
                  last_reorder_field_type = 2;
                }

              if (do_reorder)
                {
                  MOVE_FROM_FIELD_LIST_TO (gnu_tmp_bitp_list);
                  continue;
                }
            }

          /* No more bit-packed fields, move the existing ones to the end or
             put them back at their original location.  */
          else if (last_reorder_field_type == 2 || gnu_tmp_bitp_list)
            {
              last_reorder_field_type = 1;

              if (tmp_bitp_size != 0)
                {
                  if (w_reorder && tmp_last_reorder_field_type < 2)
                    warn_on_field_placement (gnu_tmp_bitp_list
                                             ? gnu_tmp_bitp_list : gnu_last,
                                             gnat_component_list,
                                             gnat_record_type, in_variant,
                                             do_reorder);

                  if (do_reorder)
                    gnu_bitp_list = chainon (gnu_tmp_bitp_list, gnu_bitp_list);

                  gnu_tmp_bitp_list = NULL_TREE;
                  tmp_bitp_size = 0;
                }
              else
                {
                  /* Rechain the temporary list in front of GNU_FIELD.  */
                  tree gnu_bitp_field = gnu_field;
                  while (gnu_tmp_bitp_list)
                    {
                      tree gnu_bitp_next = DECL_CHAIN (gnu_tmp_bitp_list);
                      DECL_CHAIN (gnu_tmp_bitp_list) = gnu_bitp_field;
                      if (gnu_last)
                        DECL_CHAIN (gnu_last) = gnu_tmp_bitp_list;
                      else
                        gnu_field_list = gnu_tmp_bitp_list;
                      gnu_bitp_field = gnu_tmp_bitp_list;
                      gnu_tmp_bitp_list = gnu_bitp_next;
                    }
                }
            }

          else
            last_reorder_field_type = 1;
        }

      gnu_last = gnu_field;
    }

#undef MOVE_FROM_FIELD_LIST_TO

  gnu_field_list = nreverse (gnu_field_list);

  /* If permitted, we reorder the fields as follows:

      1) all (groups of) fields whose length is fixed and multiple of a byte,
      2) the remaining fields whose length is fixed and not multiple of a byte,
      3) the remaining fields whose length doesn't depend on discriminants,
      4) all fields whose length depends on discriminants,
      5) the variant part,

     within the record and within each variant recursively.  */

  if (w_reorder)
    {
      /* If we have pending bit-packed fields, warn if they would be moved
         to after regular fields.  */
      if (last_reorder_field_type == 2
          && tmp_bitp_size != 0
          && tmp_last_reorder_field_type < 2)
        warn_on_field_placement (gnu_tmp_bitp_list
                                 ? gnu_tmp_bitp_list : gnu_field_list,
                                 gnat_component_list, gnat_record_type,
                                 in_variant, do_reorder);
    }

  if (do_reorder)
    {
      /* If we have pending bit-packed fields on the temporary list, we put
         them either on the bit-packed list or back on the regular list.  */
      if (gnu_tmp_bitp_list)
        {
          if (tmp_bitp_size != 0)
            gnu_bitp_list = chainon (gnu_tmp_bitp_list, gnu_bitp_list);
          else
            gnu_field_list = chainon (gnu_tmp_bitp_list, gnu_field_list);
        }

      gnu_field_list
        = chainon (gnu_field_list,
                   chainon (gnu_bitp_list,
                            chainon (gnu_var_list, gnu_self_list)));
    }

  /* Otherwise, if there is an aliased field placed after a field whose length
     depends on discriminants, we put all the fields of the latter sort, last.
     We need to do this in case an object of this record type is mutable.  */
  else if (has_aliased_after_self_field)
    gnu_field_list = chainon (gnu_field_list, gnu_self_list);

  /* If P_REP_LIST is nonzero, this means that we are asked to move the fields
     in our REP list to the previous level because this level needs them in
     order to do a correct layout, i.e. avoid having overlapping fields.  */
  if (p_gnu_rep_list && gnu_rep_list)
    *p_gnu_rep_list = chainon (*p_gnu_rep_list, gnu_rep_list);

  /* Deal with the annoying case of an extension of a record with variable size
     and partial rep clause, for which the _Parent field is forced at offset 0
     and has variable size, which we do not support below.  Note that we cannot
     do it if the field has fixed size because we rely on the presence of the
     REP part built below to trigger the reordering of the fields in a derived
     record type when all the fields have a fixed position.  */
  else if (gnu_rep_list
           && !DECL_CHAIN (gnu_rep_list)
           && TREE_CODE (DECL_SIZE (gnu_rep_list)) != INTEGER_CST
           && !variants_have_rep
           && first_free_pos
           && integer_zerop (first_free_pos)
           && integer_zerop (bit_position (gnu_rep_list)))
    {
      DECL_CHAIN (gnu_rep_list) = gnu_field_list;
      gnu_field_list = gnu_rep_list;
      gnu_rep_list = NULL_TREE;
    }

  /* Otherwise, sort the fields by bit position and put them into their own
     record, before the others, if we also have fields without rep clause.  */
  else if (gnu_rep_list)
    {
      tree gnu_rep_type, gnu_rep_part;
      int i, len = list_length (gnu_rep_list);
      tree *gnu_arr = XALLOCAVEC (tree, len);

      /* If all the fields have a rep clause, we can do a flat layout.  */
      layout_with_rep = !gnu_field_list
                        && (!gnu_variant_part || variants_have_rep);
      gnu_rep_type
        = layout_with_rep ? gnu_record_type : make_node (RECORD_TYPE);

      for (gnu_field = gnu_rep_list, i = 0;
           gnu_field;
           gnu_field = DECL_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_rep_list = NULL_TREE;
      for (i = len - 1; i >= 0; i--)
        {
          DECL_CHAIN (gnu_arr[i]) = gnu_rep_list;
          gnu_rep_list = gnu_arr[i];
          DECL_CONTEXT (gnu_arr[i]) = gnu_rep_type;
        }

      if (layout_with_rep)
        gnu_field_list = gnu_rep_list;
      else
        {
          TYPE_REVERSE_STORAGE_ORDER (gnu_rep_type)
            = TYPE_REVERSE_STORAGE_ORDER (gnu_record_type);
          finish_record_type (gnu_rep_type, gnu_rep_list, 1, debug_info);

          /* If FIRST_FREE_POS is nonzero, we need to ensure that the fields
             without rep clause are laid out starting from this position.
             Therefore, we force it as a minimal size on the REP part.  */
          gnu_rep_part
            = create_rep_part (gnu_rep_type, gnu_record_type, first_free_pos);

          /* Chain the REP part at the beginning of the field list.  */
          DECL_CHAIN (gnu_rep_part) = gnu_field_list;
          gnu_field_list = gnu_rep_part;
        }
    }

  /* Chain the variant part at the end of the field list.  */
  if (gnu_variant_part)
    gnu_field_list = chainon (gnu_field_list, gnu_variant_part);

  if (cancel_alignment)
    SET_TYPE_ALIGN (gnu_record_type, 0);

  TYPE_ARTIFICIAL (gnu_record_type) = artificial;

  finish_record_type (gnu_record_type, gnu_field_list, layout_with_rep ? 1 : 0,
                      debug_info && !maybe_unused);

  /* Chain the fields with zero size at the beginning of the field list.  */
  if (gnu_zero_list)
    TYPE_FIELDS (gnu_record_type)
      = chainon (gnu_zero_list, TYPE_FIELDS (gnu_record_type));

  return (gnu_rep_list && !p_gnu_rep_list) || variants_have_rep;
}
\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)
{
  static int var_count = 0;
  TCode tcode;
  Node_Ref_Or_Val ops[3] = { No_Uint, No_Uint, No_Uint };
  struct tree_int_map in;

  /* See if we've already saved the value for this node.  */
  if (EXPR_P (gnu_size) || DECL_P (gnu_size))
    {
      struct tree_int_map *e;

      in.base.from = gnu_size;
      e = annotate_value_cache->find (&in);

      if (e)
        return (Node_Ref_Or_Val) e->to;
    }
  else
    in.base.from = NULL_TREE;

  /* If we do not return inside this switch, TCODE will be set to the
     code to be used in a call to Create_Node.  */
  switch (TREE_CODE (gnu_size))
    {
    case INTEGER_CST:
      /* For negative values, build NEGATE_EXPR of the opposite.  Such values
         can appear for discriminants in expressions for variants.  */
      if (tree_int_cst_sgn (gnu_size) < 0)
        {
          tree t = wide_int_to_tree (sizetype, wi::neg (gnu_size));
          tcode = Negate_Expr;
          ops[0] = UI_From_gnu (t);
        }
      else
        return TREE_OVERFLOW (gnu_size) ? No_Uint : UI_From_gnu (gnu_size);
      break;

    case COMPONENT_REF:
      /* The only case we handle here is a simple discriminant reference.  */
      if (DECL_DISCRIMINANT_NUMBER (TREE_OPERAND (gnu_size, 1)))
        {
          tree ref = gnu_size;
          gnu_size = TREE_OPERAND (ref, 1);

          /* Climb up the chain of successive extensions, if any.  */
          while (TREE_CODE (TREE_OPERAND (ref, 0)) == COMPONENT_REF
                 && DECL_NAME (TREE_OPERAND (TREE_OPERAND (ref, 0), 1))
                    == parent_name_id)
            ref = TREE_OPERAND (ref, 0);

          if (TREE_CODE (TREE_OPERAND (ref, 0)) == PLACEHOLDER_EXPR)
            {
              /* Fall through to common processing as a FIELD_DECL.  */
              tcode = Discrim_Val;
              ops[0] = UI_From_gnu (DECL_DISCRIMINANT_NUMBER (gnu_size));
            }
          else
            return No_Uint;
        }
      else
        return No_Uint;
      break;

    case VAR_DECL:
      tcode = Dynamic_Val;
      ops[0] = UI_From_Int (++var_count);
      break;

    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 MINUS_EXPR:            tcode = Minus_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 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;

    case MULT_EXPR:
    case PLUS_EXPR:
      tcode = (TREE_CODE (gnu_size) == MULT_EXPR ? Mult_Expr : Plus_Expr);
      /* Fold conversions from bytes to bits into inner operations.  */
      if (TREE_CODE (TREE_OPERAND (gnu_size, 1)) == INTEGER_CST
          && CONVERT_EXPR_P (TREE_OPERAND (gnu_size, 0)))
        {
          tree inner_op = TREE_OPERAND (TREE_OPERAND (gnu_size, 0), 0);
          if (TREE_CODE (inner_op) == TREE_CODE (gnu_size)
              && TREE_CODE (TREE_OPERAND (inner_op, 1)) == INTEGER_CST)
            {
              tree inner_op_op1 = TREE_OPERAND (inner_op, 1);
              tree gnu_size_op1 = TREE_OPERAND (gnu_size, 1);
              wide_int op1;
              if (TREE_CODE (gnu_size) == MULT_EXPR)
                op1 = wi::mul (inner_op_op1, gnu_size_op1);
              else
                op1 = wi::add (inner_op_op1, gnu_size_op1);
              ops[1] = UI_From_gnu (wide_int_to_tree (sizetype, op1));
              ops[0] = annotate_value (TREE_OPERAND (inner_op, 0));
            }
        }
      break;

    case BIT_AND_EXPR:
      tcode = Bit_And_Expr;
      /* For negative values in sizetype, build NEGATE_EXPR of the opposite.
         Such values appear in expressions with aligning patterns.  Note that,
         since sizetype is unsigned, we have to jump through some hoops.   */
      if (TREE_CODE (TREE_OPERAND (gnu_size, 1)) == INTEGER_CST)
        {
          tree op1 = TREE_OPERAND (gnu_size, 1);
          wide_int signed_op1 = wi::sext (op1, TYPE_PRECISION (sizetype));
          if (wi::neg_p (signed_op1))
            {
              op1 = wide_int_to_tree (sizetype, wi::neg (signed_op1));
              ops[1] = annotate_value (build1 (NEGATE_EXPR, sizetype, op1));
            }
        }
      break;

    case CALL_EXPR:
      /* In regular mode, inline back only if symbolic annotation is requested
         in order to avoid memory explosion on big discriminated record types.
         But not in ASIS mode, as symbolic annotation is required for DDA.  */
      if (List_Representation_Info == 3 || type_annotate_only)
        {
          tree t = maybe_inline_call_in_expr (gnu_size);
          return t ? annotate_value (t) : No_Uint;
        }
      else
        return Uint_Minus_1;

    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 (int i = 0; i < TREE_CODE_LENGTH (TREE_CODE (gnu_size)); i++)
    if (ops[i] == No_Uint)
      {
        ops[i] = annotate_value (TREE_OPERAND (gnu_size, i));
        if (ops[i] == No_Uint)
          return No_Uint;
      }

  Node_Ref_Or_Val ret = Create_Node (tcode, ops[0], ops[1], ops[2]);

  /* Save the result in the cache.  */
  if (in.base.from)
    {
      struct tree_int_map **h;
      /* We can't assume the hash table data hasn't moved since the initial
         look up, so we have to search again.  Allocating and inserting an
         entry at that point would be an alternative, but then we'd better
         discard the entry if we decided not to cache it.  */
      h = annotate_value_cache->find_slot (&in, INSERT);
      gcc_assert (!*h);
      *h = ggc_alloc<tree_int_map> ();
      (*h)->base.from = in.base.from;
      (*h)->to = ret;
    }

  return ret;
}

/* Given GNAT_ENTITY, an object (constant, variable, parameter, exception)
   and GNU_TYPE, its corresponding GCC type, set Esize and Alignment to the
   size and alignment used by Gigi.  Prefer SIZE over TYPE_SIZE if non-null.
   BY_REF is true if the object is used by reference.  */

void
annotate_object (Entity_Id gnat_entity, tree gnu_type, tree size, bool by_ref)
{
  if (by_ref)
    {
      if (TYPE_IS_FAT_POINTER_P (gnu_type))
        gnu_type = TYPE_UNCONSTRAINED_ARRAY (gnu_type);
      else
        gnu_type = TREE_TYPE (gnu_type);
    }

  if (Unknown_Esize (gnat_entity))
    {
      if (TREE_CODE (gnu_type) == RECORD_TYPE
          && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
        size = TYPE_SIZE (TREE_TYPE (DECL_CHAIN (TYPE_FIELDS (gnu_type))));
      else if (!size)
        size = TYPE_SIZE (gnu_type);

      if (size)
        Set_Esize (gnat_entity, annotate_value (size));
    }

  if (Unknown_Alignment (gnat_entity))
    Set_Alignment (gnat_entity,
                   UI_From_Int (TYPE_ALIGN (gnu_type) / BITS_PER_UNIT));
}

/* Return first element of field list whose TREE_PURPOSE is the same as ELEM.
   Return NULL_TREE if there is no such element in the list.  */

static tree
purpose_member_field (const_tree elem, tree list)
{
  while (list)
    {
      tree field = TREE_PURPOSE (list);
      if (SAME_FIELD_P (field, elem))
        return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Given GNAT_ENTITY, a record type, and GNU_TYPE, its corresponding GCC type,
   set Component_Bit_Offset and Esize of the components to the position and
   size used by Gigi.  */

static void
annotate_rep (Entity_Id gnat_entity, tree gnu_type)
{
  /* For an extension, the inherited components have not been translated because
     they are fetched from the _Parent component on the fly.  */
  const bool is_extension
    = Is_Tagged_Type (gnat_entity) && Is_Derived_Type (gnat_entity);

  /* We operate by first making a list of all fields and their position (we
     can get the size easily) and then update all the sizes in the tree.  */
  tree gnu_list
    = build_position_list (gnu_type, false, size_zero_node, bitsize_zero_node,
                           BIGGEST_ALIGNMENT, NULL_TREE);

  for (Entity_Id gnat_field = First_Entity (gnat_entity);
       Present (gnat_field);
       gnat_field = Next_Entity (gnat_field))
    if ((Ekind (gnat_field) == E_Component
         && (is_extension || present_gnu_tree (gnat_field)))
        || (Ekind (gnat_field) == E_Discriminant
            && !Is_Unchecked_Union (Scope (gnat_field))))
      {
        tree t = purpose_member_field (gnat_to_gnu_field_decl (gnat_field),
                                       gnu_list);
        if (t)
          {
            tree parent_offset;

            /* If we are just annotating types and the type is tagged, the tag
               and the parent components are not generated by the front-end so
               we need to add the appropriate offset to each component without
               representation clause.  */
            if (type_annotate_only
                && Is_Tagged_Type (gnat_entity)
                && No (Component_Clause (gnat_field)))
              {
                /* 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);

                if (TYPE_FIELDS (gnu_type))
                  parent_offset
                    = round_up (parent_offset,
                                DECL_ALIGN (TYPE_FIELDS (gnu_type)));
              }
            else
              parent_offset = bitsize_zero_node;

            Set_Component_Bit_Offset
              (gnat_field,
               annotate_value
                 (size_binop (PLUS_EXPR,
                              bit_from_pos (TREE_VEC_ELT (TREE_VALUE (t), 0),
                                            TREE_VEC_ELT (TREE_VALUE (t), 2)),
                              parent_offset)));

            Set_Esize (gnat_field,
                       annotate_value (DECL_SIZE (TREE_PURPOSE (t))));
          }
        else if (is_extension)
          {
            /* If there is no entry, this is an inherited component whose
               position is the same as in the parent type.  */
            Entity_Id gnat_orig_field = Original_Record_Component (gnat_field);

            /* If we are just annotating types, discriminants renaming those of
               the parent have no entry so deal with them specifically.  */
            if (type_annotate_only
                && gnat_orig_field == gnat_field
                && Ekind (gnat_field) == E_Discriminant)
              gnat_orig_field = Corresponding_Discriminant (gnat_field);

            Set_Component_Bit_Offset (gnat_field,
                                      Component_Bit_Offset (gnat_orig_field));

            Set_Esize (gnat_field, Esize (gnat_orig_field));
          }
      }
}
\f
/* Scan all fields in GNU_TYPE and return a TREE_LIST where TREE_PURPOSE is
   the FIELD_DECL and TREE_VALUE a TREE_VEC containing the byte position, the
   value to be placed into DECL_OFFSET_ALIGN and the bit position.  The list
   of fields is flattened, except for variant parts if DO_NOT_FLATTEN_VARIANT
   is set to true.  GNU_POS is to be added to the position, GNU_BITPOS to the
   bit position, OFFSET_ALIGN is the present offset alignment.  GNU_LIST is a
   pre-existing list to be chained to the newly created entries.  */

static tree
build_position_list (tree gnu_type, bool do_not_flatten_variant, tree gnu_pos,
                     tree gnu_bitpos, unsigned int offset_align, tree gnu_list)
{
  tree gnu_field;

  for (gnu_field = TYPE_FIELDS (gnu_type);
       gnu_field;
       gnu_field = DECL_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));
      tree v = make_tree_vec (3);

      TREE_VEC_ELT (v, 0) = gnu_our_offset;
      TREE_VEC_ELT (v, 1) = size_int (our_offset_align);
      TREE_VEC_ELT (v, 2) = gnu_our_bitpos;
      gnu_list = tree_cons (gnu_field, v, gnu_list);

      /* Recurse on internal fields, flattening the nested fields except for
         those in the variant part, if requested.  */
      if (DECL_INTERNAL_P (gnu_field))
        {
          tree gnu_field_type = TREE_TYPE (gnu_field);
          if (do_not_flatten_variant
              && TREE_CODE (gnu_field_type) == QUAL_UNION_TYPE)
            gnu_list
              = build_position_list (gnu_field_type, do_not_flatten_variant,
                                     size_zero_node, bitsize_zero_node,
                                     BIGGEST_ALIGNMENT, gnu_list);
          else
            gnu_list
              = build_position_list (gnu_field_type, do_not_flatten_variant,
                                     gnu_our_offset, gnu_our_bitpos,
                                     our_offset_align, gnu_list);
        }
    }

  return gnu_list;
}

/* Return a list describing the substitutions needed to reflect the
   discriminant substitutions from GNAT_TYPE to GNAT_SUBTYPE.  They can
   be in any order.  The values in an element of the list are in the form
   of operands to SUBSTITUTE_IN_EXPR.  DEFINITION is true if this is for
   a definition of GNAT_SUBTYPE.  */

static vec<subst_pair>
build_subst_list (Entity_Id gnat_subtype, Entity_Id gnat_type, bool definition)
{
  vec<subst_pair> gnu_list = vNULL;
  Entity_Id gnat_discrim;
  Node_Id gnat_constr;

  for (gnat_discrim = First_Stored_Discriminant (gnat_type),
       gnat_constr = First_Elmt (Stored_Constraint (gnat_subtype));
       Present (gnat_discrim);
       gnat_discrim = Next_Stored_Discriminant (gnat_discrim),
       gnat_constr = Next_Elmt (gnat_constr))
    /* Ignore access discriminants.  */
    if (!Is_Access_Type (Etype (Node (gnat_constr))))
      {
        tree gnu_field = gnat_to_gnu_field_decl (gnat_discrim);
        tree replacement = convert (TREE_TYPE (gnu_field),
                                    elaborate_expression
                                    (Node (gnat_constr), gnat_subtype,
                                     get_entity_char (gnat_discrim),
                                     definition, true, false));
        subst_pair s = { gnu_field, replacement };
        gnu_list.safe_push (s);
      }

  return gnu_list;
}

/* Scan all fields in QUAL_UNION_TYPE and return a list describing the
   variants of QUAL_UNION_TYPE that are still relevant after applying
   the substitutions described in SUBST_LIST.  GNU_LIST is a pre-existing
   list to be prepended to the newly created entries.  */

static vec<variant_desc>
build_variant_list (tree qual_union_type, vec<subst_pair> subst_list,
                    vec<variant_desc> gnu_list)
{
  tree gnu_field;

  for (gnu_field = TYPE_FIELDS (qual_union_type);
       gnu_field;
       gnu_field = DECL_CHAIN (gnu_field))
    {
      tree qual = DECL_QUALIFIER (gnu_field);
      unsigned int i;
      subst_pair *s;

      FOR_EACH_VEC_ELT (subst_list, i, s)
        qual = SUBSTITUTE_IN_EXPR (qual, s->discriminant, s->replacement);

      /* If the new qualifier is not unconditionally false, its variant may
         still be accessed.  */
      if (!integer_zerop (qual))
        {
          tree variant_type = TREE_TYPE (gnu_field), variant_subpart;
          variant_desc v = { variant_type, gnu_field, qual, NULL_TREE };

          gnu_list.safe_push (v);

          /* Recurse on the variant subpart of the variant, if any.  */
          variant_subpart = get_variant_part (variant_type);
          if (variant_subpart)
            gnu_list = build_variant_list (TREE_TYPE (variant_subpart),
                                           subst_list, gnu_list);

          /* If the new qualifier is unconditionally true, the subsequent
             variants cannot be accessed.  */
          if (integer_onep (qual))
            break;
        }
    }

  return gnu_list;
}
\f
/* UINT_SIZE is a Uint giving the specified size for an object of GNU_TYPE
   corresponding to GNAT_OBJECT.  If the size is valid, return an INTEGER_CST
   corresponding to its value.  Otherwise, return NULL_TREE.  KIND is set to
   VAR_DECL if we are specifying the size of 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 only for error messages.  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;

  /* Return 0 if no size was specified.  */
  if (uint_size == No_Uint)
    return NULL_TREE;

  /* Ignore a negative size since that corresponds to our back-annotation.  */
  if (UI_Lt (uint_size, Uint_0))
    return NULL_TREE;

  /* Find the node to use for error messages.  */
  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;

  /* Get the size as an INTEGER_CST.  Issue an error if a size was specified
     but cannot be represented in bitsizetype.  */
  size = UI_To_gnu (uint_size, bitsizetype);
  if (TREE_OVERFLOW (size))
    {
      if (component_p)
        post_error_ne ("component size for& is too large", gnat_error_node,
                       gnat_object);
      else
        post_error_ne ("size for& is too large", gnat_error_node,
                       gnat_object);
      return NULL_TREE;
    }

  /* Ignore a zero size if it is not permitted.  */
  if (!zero_ok && integer_zerop (size))
    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
     already verified the size, so we need not do it here (which would mean
     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);

  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);

  /* Modify the size of a discriminated type to be the maximum size.  */
  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_IS_FAT_POINTER_P (gnu_type))
    {
      scalar_int_mode p_mode = NARROWEST_INT_MODE;
      while (!targetm.valid_pointer_mode (p_mode))
        p_mode = GET_MODE_WIDER_MODE (p_mode).require ();
      type_size = bitsize_int (GET_MODE_BITSIZE (p_mode));
    }

  /* Issue an error either if the default size of the object isn't a constant
     or if the new size is smaller than it.  */
  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);
      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)
{
  Node_Id gnat_attr_node;
  tree old_size, size;

  /* Do nothing if no size was specified.  */
  if (uint_size == No_Uint)
    return;

  /* Ignore a negative size since that corresponds to our back-annotation.  */
  if (UI_Lt (uint_size, Uint_0))
    return;

  /* Only issue an error if a Value_Size clause was explicitly given.
     Otherwise, we'd be duplicating an error on the Size clause.  */
  gnat_attr_node
    = Get_Attribute_Definition_Clause (gnat_entity, Attr_Value_Size);

  /* Get the size as an INTEGER_CST.  Issue an error if a size was specified
     but cannot be represented in bitsizetype.  */
  size = UI_To_gnu (uint_size, bitsizetype);
  if (TREE_OVERFLOW (size))
    {
      if (Present (gnat_attr_node))
        post_error_ne ("Value_Size for& is too large", gnat_attr_node,
                       gnat_entity);
      return;
    }

  /* Ignore a zero size unless a Value_Size clause exists, or a size clause
     exists, or this is an integer type, in which case the front-end will
     have always set it.  */
  if (No (gnat_attr_node)
      && integer_zerop (size)
      && !Has_Size_Clause (gnat_entity)
      && !Is_Discrete_Or_Fixed_Point_Type (gnat_entity))
    return;

  old_size = rm_size (gnu_type);

  /* If the old size is self-referential, get the maximum size.  */
  if (CONTAINS_PLACEHOLDER_P (old_size))
    old_size = max_size (old_size, true);

  /* Issue an error either if the old size of the object isn't a constant or
     if the new size is smaller than it.  The front-end has already verified
     this for scalar and packed array types.  */
  if (TREE_CODE (old_size) != INTEGER_CST
      || TREE_OVERFLOW (old_size)
      || (AGGREGATE_TYPE_P (gnu_type)
          && !(TREE_CODE (gnu_type) == ARRAY_TYPE
               && TYPE_PACKED_ARRAY_TYPE_P (gnu_type))
          && !(TYPE_IS_PADDING_P (gnu_type)
               && TREE_CODE (TREE_TYPE (TYPE_FIELDS (gnu_type))) == ARRAY_TYPE
               && TYPE_PACKED_ARRAY_TYPE_P
                  (TREE_TYPE (TYPE_FIELDS (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 proper for integral types...  */
  if ((TREE_CODE (gnu_type) == INTEGER_TYPE
       && Is_Discrete_Or_Fixed_Point_Type (gnat_entity))
      || (TREE_CODE (gnu_type) == ENUMERAL_TYPE
          || TREE_CODE (gnu_type) == BOOLEAN_TYPE))
    SET_TYPE_RM_SIZE (gnu_type, size);

  /* ...or the Ada size for record and union types.  */
  else if (RECORD_OR_UNION_TYPE_P (gnu_type)
           && !TYPE_FAT_POINTER_P (gnu_type))
    SET_TYPE_ADA_SIZE (gnu_type, size);
}
\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.  Note, for the implicit
     base type of an array type, the alignment clause is on the first
     subtype.  */
  if (Present (Alignment_Clause (gnat_entity)))
    gnat_error_node = Expression (Alignment_Clause (gnat_entity));

  else if (Is_Itype (gnat_entity)
           && Is_Array_Type (gnat_entity)
           && Etype (gnat_entity) == gnat_entity
           && Present (Alignment_Clause (First_Subtype (gnat_entity))))
    gnat_error_node =
      Expression (Alignment_Clause (First_Subtype (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)
    {
      unsigned int double_align;
      bool is_capped_double, align_clause;

      /* If the default alignment of "double" or larger scalar types is
         specifically capped and the new alignment is above the cap, do
         not post an error and change the alignment only if there is an
         alignment clause; this makes it possible to have the associated
         GCC type overaligned by default for performance reasons.  */
      if ((double_align = double_float_alignment) > 0)
        {
          Entity_Id gnat_type
            = Is_Type (gnat_entity) ? gnat_entity : Etype (gnat_entity);
          is_capped_double
            = is_double_float_or_array (gnat_type, &align_clause);
        }
      else if ((double_align = double_scalar_alignment) > 0)
        {
          Entity_Id gnat_type
            = Is_Type (gnat_entity) ? gnat_entity : Etype (gnat_entity);
          is_capped_double
            = is_double_scalar_or_array (gnat_type, &align_clause);
        }
      else
        is_capped_double = align_clause = false;

      if (is_capped_double && new_align >= double_align)
        {
          if (align_clause)
            align = new_align * BITS_PER_UNIT;
        }
      else
        {
          if (is_capped_double)
            align = double_align * BITS_PER_UNIT;

          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;
}
\f
/* Verify that TYPE is something we can implement atomically.  If not, issue
   an error for GNAT_ENTITY.  COMPONENT_P is true if we are being called to
   process a component type.  */

static void
check_ok_for_atomic_type (tree type, Entity_Id gnat_entity, bool component_p)
{
  Node_Id gnat_error_point = gnat_entity;
  Node_Id gnat_node;
  machine_mode mode;
  enum mode_class mclass;
  unsigned int align;
  tree size;

  /* If this is an anonymous base type, nothing to check, the error will be
     reported on the source type if need be.  */
  if (!Comes_From_Source (gnat_entity))
    return;

  mode = TYPE_MODE (type);
  mclass = GET_MODE_CLASS (mode);
  align = TYPE_ALIGN (type);
  size = TYPE_SIZE (type);

  /* Consider all aligned floating-point types atomic and any aligned types
     that are represented by integers no wider than a machine word.  */
  scalar_int_mode int_mode;
  if ((mclass == MODE_FLOAT
       || (is_a <scalar_int_mode> (mode, &int_mode)
           && GET_MODE_BITSIZE (int_mode) <= BITS_PER_WORD))
      && align >= GET_MODE_ALIGNMENT (mode))
    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 (Nkind (gnat_node) == N_Pragma)
      {
        unsigned char pragma_id
          = Get_Pragma_Id (Chars (Pragma_Identifier (gnat_node)));

        if ((pragma_id == Pragma_Atomic && !component_p)
            || (pragma_id == Pragma_Atomic_Components && component_p))
          {
            gnat_error_point = First (Pragma_Argument_Associations (gnat_node));
            break;
          }
      }

  if (component_p)
    post_error_ne ("atomic access to component of & cannot be guaranteed",
                   gnat_error_point, gnat_entity);
  else if (Is_Volatile_Full_Access (gnat_entity))
    post_error_ne ("volatile full access to & cannot be guaranteed",
                   gnat_error_point, gnat_entity);
  else
    post_error_ne ("atomic access to & cannot be guaranteed",
                   gnat_error_point, gnat_entity);
}
\f

/* Helper for the intrin compatibility checks family.  Evaluate whether
   two types are definitely incompatible.  */

static bool
intrin_types_incompatible_p (tree t1, tree t2)
{
  enum tree_code code;

  if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return false;

  if (TYPE_MODE (t1) != TYPE_MODE (t2))
    return true;

  if (TREE_CODE (t1) != TREE_CODE (t2))
    return true;

  code = TREE_CODE (t1);

  switch (code)
    {
    case INTEGER_TYPE:
    case REAL_TYPE:
      return TYPE_PRECISION (t1) != TYPE_PRECISION (t2);

    case POINTER_TYPE:
    case REFERENCE_TYPE:
      /* Assume designated types are ok.  We'd need to account for char * and
         void * variants to do better, which could rapidly get messy and isn't
         clearly worth the effort.  */
      return false;

    default:
      break;
    }

  return false;
}

/* Helper for intrin_profiles_compatible_p, to perform compatibility checks
   on the Ada/builtin argument lists for the INB binding.  */

static bool
intrin_arglists_compatible_p (intrin_binding_t * inb)
{
  function_args_iterator ada_iter, btin_iter;

  function_args_iter_init (&ada_iter, inb->ada_fntype);
  function_args_iter_init (&btin_iter, inb->btin_fntype);

  /* Sequence position of the last argument we checked.  */
  int argpos = 0;

  while (true)
    {
      tree ada_type = function_args_iter_cond (&ada_iter);
      tree btin_type = function_args_iter_cond (&btin_iter);

      /* If we've exhausted both lists simultaneously, we're done.  */
      if (!ada_type && !btin_type)
        break;

      /* If one list is shorter than the other, they fail to match.  */
      if (!ada_type || !btin_type)
        return false;

      /* If we're done with the Ada args and not with the internal builtin
         args, or the other way around, complain.  */
      if (ada_type == void_type_node
          && btin_type != void_type_node)
        {
          post_error ("?Ada arguments list too short!", inb->gnat_entity);
          return false;
        }

      if (btin_type == void_type_node
          && ada_type != void_type_node)
        {
          post_error_ne_num ("?Ada arguments list too long ('> ^)!",
                             inb->gnat_entity, inb->gnat_entity, argpos);
          return false;
        }

      /* Otherwise, check that types match for the current argument.  */
      argpos ++;
      if (intrin_types_incompatible_p (ada_type, btin_type))
        {
          post_error_ne_num ("?intrinsic binding type mismatch on argument ^!",
                             inb->gnat_entity, inb->gnat_entity, argpos);
          return false;
        }


      function_args_iter_next (&ada_iter);
      function_args_iter_next (&btin_iter);
    }

  return true;
}

/* Helper for intrin_profiles_compatible_p, to perform compatibility checks
   on the Ada/builtin return values for the INB binding.  */

static bool
intrin_return_compatible_p (intrin_binding_t * inb)
{
  tree ada_return_type = TREE_TYPE (inb->ada_fntype);
  tree btin_return_type = TREE_TYPE (inb->btin_fntype);

  /* Accept function imported as procedure, common and convenient.  */
  if (VOID_TYPE_P (ada_return_type)
      && !VOID_TYPE_P (btin_return_type))
    return true;

  /* Check return types compatibility otherwise.  Note that this
     handles void/void as well.  */
  if (intrin_types_incompatible_p (btin_return_type, ada_return_type))
    {
      post_error ("?intrinsic binding type mismatch on return value!",
                  inb->gnat_entity);
      return false;
    }

  return true;
}

/* Check and return whether the Ada and gcc builtin profiles bound by INB are
   compatible.  Issue relevant warnings when they are not.

   This is intended as a light check to diagnose the most obvious cases, not
   as a full fledged type compatibility predicate.  It is the programmer's
   responsibility to ensure correctness of the Ada declarations in Imports,
   especially when binding straight to a compiler internal.  */

static bool
intrin_profiles_compatible_p (intrin_binding_t * inb)
{
  /* Check compatibility on return values and argument lists, each responsible
     for posting warnings as appropriate.  Ensure use of the proper sloc for
     this purpose.  */

  bool arglists_compatible_p, return_compatible_p;
  location_t saved_location = input_location;

  Sloc_to_locus (Sloc (inb->gnat_entity), &input_location);

  return_compatible_p = intrin_return_compatible_p (inb);
  arglists_compatible_p = intrin_arglists_compatible_p (inb);

  input_location = saved_location;

  return return_compatible_p && arglists_compatible_p;
}
\f
/* Return a FIELD_DECL node modeled on OLD_FIELD.  FIELD_TYPE is its type
   and RECORD_TYPE is the type of the parent.  If SIZE is nonzero, it is the
   specified size for this field.  POS_LIST is a position list describing
   the layout of OLD_FIELD and SUBST_LIST a substitution list to be applied
   to this layout.  */

static tree
create_field_decl_from (tree old_field, tree field_type, tree record_type,
                        tree size, tree pos_list,
                        vec<subst_pair> subst_list)
{
  tree t = TREE_VALUE (purpose_member (old_field, pos_list));
  tree pos = TREE_VEC_ELT (t, 0), bitpos = TREE_VEC_ELT (t, 2);
  unsigned int offset_align = tree_to_uhwi (TREE_VEC_ELT (t, 1));
  tree new_pos, new_field;
  unsigned int i;
  subst_pair *s;

  if (CONTAINS_PLACEHOLDER_P (pos))
    FOR_EACH_VEC_ELT (subst_list, i, s)
      pos = SUBSTITUTE_IN_EXPR (pos, s->discriminant, s->replacement);

  /* 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.  */
  if (TREE_CONSTANT (pos))
    new_pos = bit_from_pos (pos, bitpos);
  else
    new_pos = NULL_TREE;

  new_field
    = create_field_decl (DECL_NAME (old_field), field_type, record_type,
                         size, new_pos, DECL_PACKED (old_field),
                         !DECL_NONADDRESSABLE_P (old_field));

  if (!new_pos)
    {
      normalize_offset (&pos, &bitpos, offset_align);
      /* Finalize the position.  */
      DECL_FIELD_OFFSET (new_field) = variable_size (pos);
      DECL_FIELD_BIT_OFFSET (new_field) = bitpos;
      SET_DECL_OFFSET_ALIGN (new_field, offset_align);
      DECL_SIZE (new_field) = size;
      DECL_SIZE_UNIT (new_field)
        = convert (sizetype,
                   size_binop (CEIL_DIV_EXPR, size, bitsize_unit_node));
      layout_decl (new_field, DECL_OFFSET_ALIGN (new_field));
    }

  DECL_INTERNAL_P (new_field) = DECL_INTERNAL_P (old_field);
  SET_DECL_ORIGINAL_FIELD_TO_FIELD (new_field, old_field);
  DECL_DISCRIMINANT_NUMBER (new_field) = DECL_DISCRIMINANT_NUMBER (old_field);
  TREE_THIS_VOLATILE (new_field) = TREE_THIS_VOLATILE (old_field);

  return new_field;
}

/* Create the REP part of RECORD_TYPE with REP_TYPE.  If MIN_SIZE is nonzero,
   it is the minimal size the REP_PART must have.  */

static tree
create_rep_part (tree rep_type, tree record_type, tree min_size)
{
  tree field;

  if (min_size && !tree_int_cst_lt (TYPE_SIZE (rep_type), min_size))
    min_size = NULL_TREE;

  field = create_field_decl (get_identifier ("REP"), rep_type, record_type,
                             min_size, NULL_TREE, 0, 1);
  DECL_INTERNAL_P (field) = 1;

  return field;
}

/* Return the REP part of RECORD_TYPE, if any.  Otherwise return NULL.  */

static tree
get_rep_part (tree record_type)
{
  tree field = TYPE_FIELDS (record_type);

  /* The REP part is the first field, internal, another record, and its name
     starts with an 'R'.  */
  if (field
      && DECL_INTERNAL_P (field)
      && TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
      && IDENTIFIER_POINTER (DECL_NAME (field)) [0] == 'R')
    return field;

  return NULL_TREE;
}

/* Return the variant part of RECORD_TYPE, if any.  Otherwise return NULL.  */

tree
get_variant_part (tree record_type)
{
  tree field;

  /* The variant part is the only internal field that is a qualified union.  */
  for (field = TYPE_FIELDS (record_type); field; field = DECL_CHAIN (field))
    if (DECL_INTERNAL_P (field)
        && TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE)
      return field;

  return NULL_TREE;
}

/* Return a new variant part modeled on OLD_VARIANT_PART.  VARIANT_LIST is
   the list of variants to be used and RECORD_TYPE is the type of the parent.
   POS_LIST is a position list describing the layout of fields present in
   OLD_VARIANT_PART and SUBST_LIST a substitution list to be applied to this
   layout.  DEBUG_INFO_P is true if we need to write debug information.  */

static tree
create_variant_part_from (tree old_variant_part,
                          vec<variant_desc> variant_list,
                          tree record_type, tree pos_list,
                          vec<subst_pair> subst_list,
                          bool debug_info_p)
{
  tree offset = DECL_FIELD_OFFSET (old_variant_part);
  tree old_union_type = TREE_TYPE (old_variant_part);
  tree new_union_type, new_variant_part;
  tree union_field_list = NULL_TREE;
  variant_desc *v;
  unsigned int i;

  /* First create the type of the variant part from that of the old one.  */
  new_union_type = make_node (QUAL_UNION_TYPE);
  TYPE_NAME (new_union_type)
    = concat_name (TYPE_NAME (record_type),
                   IDENTIFIER_POINTER (DECL_NAME (old_variant_part)));

  /* If the position of the variant part is constant, subtract it from the
     size of the type of the parent to get the new size.  This manual CSE
     reduces the code size when not optimizing.  */
  if (TREE_CODE (offset) == INTEGER_CST
      && TYPE_SIZE (record_type)
      && TYPE_SIZE_UNIT (record_type))
    {
      tree bitpos = DECL_FIELD_BIT_OFFSET (old_variant_part);
      tree first_bit = bit_from_pos (offset, bitpos);
      TYPE_SIZE (new_union_type)
        = size_binop (MINUS_EXPR, TYPE_SIZE (record_type), first_bit);
      TYPE_SIZE_UNIT (new_union_type)
        = size_binop (MINUS_EXPR, TYPE_SIZE_UNIT (record_type),
                      byte_from_pos (offset, bitpos));
      SET_TYPE_ADA_SIZE (new_union_type,
                         size_binop (MINUS_EXPR, TYPE_ADA_SIZE (record_type),
                                     first_bit));
      SET_TYPE_ALIGN (new_union_type, TYPE_ALIGN (old_union_type));
      relate_alias_sets (new_union_type, old_union_type, ALIAS_SET_COPY);
    }
  else
    copy_and_substitute_in_size (new_union_type, old_union_type, subst_list);

  /* Now finish up the new variants and populate the union type.  */
  FOR_EACH_VEC_ELT_REVERSE (variant_list, i, v)
    {
      tree old_field = v->field, new_field;
      tree old_variant, old_variant_subpart, new_variant, field_list;

      /* Skip variants that don't belong to this nesting level.  */
      if (DECL_CONTEXT (old_field) != old_union_type)
        continue;

      /* Retrieve the list of fields already added to the new variant.  */
      new_variant = v->new_type;
      field_list = TYPE_FIELDS (new_variant);

      /* If the old variant had a variant subpart, we need to create a new
         variant subpart and add it to the field list.  */
      old_variant = v->type;
      old_variant_subpart = get_variant_part (old_variant);
      if (old_variant_subpart)
        {
          tree new_variant_subpart
            = create_variant_part_from (old_variant_subpart, variant_list,
                                        new_variant, pos_list, subst_list,
                                        debug_info_p);
          DECL_CHAIN (new_variant_subpart) = field_list;
          field_list = new_variant_subpart;
        }

      /* Finish up the new variant and create the field.  */
      finish_record_type (new_variant, nreverse (field_list), 2, debug_info_p);
      compute_record_mode (new_variant);
      create_type_decl (TYPE_NAME (new_variant), new_variant, true,
                        debug_info_p, Empty);

      new_field
        = create_field_decl_from (old_field, new_variant, new_union_type,
                                  TYPE_SIZE (new_variant),
                                  pos_list, subst_list);
      DECL_QUALIFIER (new_field) = v->qual;
      DECL_INTERNAL_P (new_field) = 1;
      DECL_CHAIN (new_field) = union_field_list;
      union_field_list = new_field;
    }

  /* Finish up the union type and create the variant part.  Note that we don't
     reverse the field list because VARIANT_LIST has been traversed in reverse
     order.  */
  finish_record_type (new_union_type, union_field_list, 2, debug_info_p);
  compute_record_mode (new_union_type);
  create_type_decl (TYPE_NAME (new_union_type), new_union_type, true,
                    debug_info_p, Empty);

  new_variant_part
    = create_field_decl_from (old_variant_part, new_union_type, record_type,
                              TYPE_SIZE (new_union_type),
                              pos_list, subst_list);
  DECL_INTERNAL_P (new_variant_part) = 1;

  /* With multiple discriminants it is possible for an inner variant to be
     statically selected while outer ones are not; in this case, the list
     of fields of the inner variant is not flattened and we end up with a
     qualified union with a single member.  Drop the useless container.  */
  if (!DECL_CHAIN (union_field_list))
    {
      DECL_CONTEXT (union_field_list) = record_type;
      DECL_FIELD_OFFSET (union_field_list)
        = DECL_FIELD_OFFSET (new_variant_part);
      DECL_FIELD_BIT_OFFSET (union_field_list)
        = DECL_FIELD_BIT_OFFSET (new_variant_part);
      SET_DECL_OFFSET_ALIGN (union_field_list,
                             DECL_OFFSET_ALIGN (new_variant_part));
      new_variant_part = union_field_list;
    }

  return new_variant_part;
}

/* Copy the size (and alignment and alias set) from OLD_TYPE to NEW_TYPE,
   which are both RECORD_TYPE, after applying the substitutions described
   in SUBST_LIST.  */

static void
copy_and_substitute_in_size (tree new_type, tree old_type,
                             vec<subst_pair> subst_list)
{
  unsigned int i;
  subst_pair *s;

  TYPE_SIZE (new_type) = TYPE_SIZE (old_type);
  TYPE_SIZE_UNIT (new_type) = TYPE_SIZE_UNIT (old_type);
  SET_TYPE_ADA_SIZE (new_type, TYPE_ADA_SIZE (old_type));
  SET_TYPE_ALIGN (new_type, TYPE_ALIGN (old_type));
  relate_alias_sets (new_type, old_type, ALIAS_SET_COPY);

  if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (new_type)))
    FOR_EACH_VEC_ELT (subst_list, i, s)
      TYPE_SIZE (new_type)
        = SUBSTITUTE_IN_EXPR (TYPE_SIZE (new_type),
                              s->discriminant, s->replacement);

  if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE_UNIT (new_type)))
    FOR_EACH_VEC_ELT (subst_list, i, s)
      TYPE_SIZE_UNIT (new_type)
        = SUBSTITUTE_IN_EXPR (TYPE_SIZE_UNIT (new_type),
                              s->discriminant, s->replacement);

  if (CONTAINS_PLACEHOLDER_P (TYPE_ADA_SIZE (new_type)))
    FOR_EACH_VEC_ELT (subst_list, i, s)
      SET_TYPE_ADA_SIZE
        (new_type, SUBSTITUTE_IN_EXPR (TYPE_ADA_SIZE (new_type),
                                       s->discriminant, s->replacement));

  /* Finalize the size.  */
  TYPE_SIZE (new_type) = variable_size (TYPE_SIZE (new_type));
  TYPE_SIZE_UNIT (new_type) = variable_size (TYPE_SIZE_UNIT (new_type));
}

/* Return true if DISC is a stored discriminant of RECORD_TYPE.  */

static inline bool
is_stored_discriminant (Entity_Id discr, Entity_Id record_type)
{
  if (Is_Tagged_Type (record_type))
    return No (Corresponding_Discriminant (discr));
  else if (Ekind (record_type) == E_Record_Type)
    return Original_Record_Component (discr) == discr;
  else
    return true;
}

/* Copy the layout from {GNAT,GNU}_OLD_TYPE to {GNAT,GNU}_NEW_TYPE, which are
   both record types, after applying the substitutions described in SUBST_LIST.
   DEBUG_INFO_P is true if we need to write debug information for NEW_TYPE.  */

static void
copy_and_substitute_in_layout (Entity_Id gnat_new_type,
                               Entity_Id gnat_old_type,
                               tree gnu_new_type,
                               tree gnu_old_type,
                               vec<subst_pair> gnu_subst_list,
                               bool debug_info_p)
{
  const bool is_subtype = (Ekind (gnat_new_type) == E_Record_Subtype);
  tree gnu_field_list = NULL_TREE;
  bool selected_variant, all_constant_pos = true;
  vec<variant_desc> gnu_variant_list;

  /* Look for REP and variant parts in the old type.  */
  tree gnu_rep_part = get_rep_part (gnu_old_type);
  tree gnu_variant_part = get_variant_part (gnu_old_type);

  /* If there is a variant part, we must compute whether the constraints
     statically select a particular variant.  If so, we simply drop the
     qualified union and flatten the list of fields.  Otherwise we will
     build a new qualified union for the variants that are still relevant.  */
  if (gnu_variant_part)
    {
      variant_desc *v;
      unsigned int i;

      gnu_variant_list = build_variant_list (TREE_TYPE (gnu_variant_part),
                                             gnu_subst_list, vNULL);

      /* If all the qualifiers are unconditionally true, the innermost variant
         is statically selected.  */
      selected_variant = true;
      FOR_EACH_VEC_ELT (gnu_variant_list, i, v)
        if (!integer_onep (v->qual))
          {
            selected_variant = false;
            break;
          }

      /* Otherwise, create the new variants.  */
      if (!selected_variant)
        FOR_EACH_VEC_ELT (gnu_variant_list, i, v)
          {
            tree old_variant = v->type;
            tree new_variant = make_node (RECORD_TYPE);
            tree suffix
              = concat_name (DECL_NAME (gnu_variant_part),
                             IDENTIFIER_POINTER (DECL_NAME (v->field)));
            TYPE_NAME (new_variant)
              = concat_name (TYPE_NAME (gnu_new_type),
                             IDENTIFIER_POINTER (suffix));
            TYPE_REVERSE_STORAGE_ORDER (new_variant)
              = TYPE_REVERSE_STORAGE_ORDER (gnu_new_type);
            copy_and_substitute_in_size (new_variant, old_variant,
                                         gnu_subst_list);
            v->new_type = new_variant;
          }
    }
  else
    {
      gnu_variant_list.create (0);
      selected_variant = false;
    }

  /* Make a list of fields and their position in the old type.  */
  tree gnu_pos_list
    = build_position_list (gnu_old_type,
                           gnu_variant_list.exists () && !selected_variant,
                           size_zero_node, bitsize_zero_node,
                           BIGGEST_ALIGNMENT, NULL_TREE);

  /* Now go down every component in the new type and compute its size and
     position from those of the component in the old type and the stored
     constraints of the new type.  */
  Entity_Id gnat_field, gnat_old_field;
  for (gnat_field = First_Entity (gnat_new_type);
       Present (gnat_field);
       gnat_field = Next_Entity (gnat_field))
    if ((Ekind (gnat_field) == E_Component
         || (Ekind (gnat_field) == E_Discriminant
             && is_stored_discriminant (gnat_field, gnat_new_type)))
        && (gnat_old_field = is_subtype
                             ? Original_Record_Component (gnat_field)
                             : Corresponding_Record_Component (gnat_field))
        && Underlying_Type (Scope (gnat_old_field)) == gnat_old_type
        && present_gnu_tree (gnat_old_field))
      {
        Name_Id gnat_name = Chars (gnat_field);
        tree gnu_old_field = get_gnu_tree (gnat_old_field);
        if (TREE_CODE (gnu_old_field) == COMPONENT_REF)
          gnu_old_field = TREE_OPERAND (gnu_old_field, 1);
        tree gnu_context = DECL_CONTEXT (gnu_old_field);
        tree gnu_field, gnu_field_type, gnu_size, gnu_pos;
        tree gnu_cont_type, gnu_last = NULL_TREE;

        /* If the type is the same, retrieve the GCC type from the
           old field to take into account possible adjustments.  */
        if (Etype (gnat_field) == Etype (gnat_old_field))
          gnu_field_type = TREE_TYPE (gnu_old_field);
        else
          gnu_field_type = gnat_to_gnu_type (Etype (gnat_field));

        /* If there was a component clause, the field types must be the same
           for the old and new types, 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 (gnat_old_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 with 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 (RECORD_OR_UNION_TYPE_P (gnu_field_type)
                && !TYPE_FAT_POINTER_P (gnu_field_type)
                && tree_fits_uhwi_p (TYPE_SIZE (gnu_field_type)))
              gnu_field_type = make_packable_type (gnu_field_type, true);
          }

        else
          gnu_size = TYPE_SIZE (gnu_field_type);

        /* If the context of the old field is the old type or its REP part,
           put the field directly in the new type; otherwise look up the
           context in the variant list and put the field either in the new
           type if there is a selected variant or in one new variant.  */
        if (gnu_context == gnu_old_type
            || (gnu_rep_part && gnu_context == TREE_TYPE (gnu_rep_part)))
          gnu_cont_type = gnu_new_type;
        else
          {
            variant_desc *v;
            unsigned int i;
            tree rep_part;

            FOR_EACH_VEC_ELT (gnu_variant_list, i, v)
              if (gnu_context == v->type
                  || ((rep_part = get_rep_part (v->type))
                      && gnu_context == TREE_TYPE (rep_part)))
                break;

            if (v)
              gnu_cont_type = selected_variant ? gnu_new_type : v->new_type;
            else
              /* The front-end may pass us "ghost" components if it fails to
                 recognize that a constrain statically selects a particular
                 variant.  Discard them.  */
              continue;
          }

        /* Now create the new field modeled on the old one.  */
        gnu_field
          = create_field_decl_from (gnu_old_field, gnu_field_type,
                                    gnu_cont_type, gnu_size,
                                    gnu_pos_list, gnu_subst_list);
        gnu_pos = DECL_FIELD_OFFSET (gnu_field);

        /* If the context is a variant, put it in the new variant directly.  */
        if (gnu_cont_type != gnu_new_type)
          {
            DECL_CHAIN (gnu_field) = TYPE_FIELDS (gnu_cont_type);
            TYPE_FIELDS (gnu_cont_type) = gnu_field;
          }

        /* To match the layout crafted in components_to_record, if this is
           the _Tag or _Parent field, put it before any other fields.  */
        else if (gnat_name == Name_uTag || gnat_name == Name_uParent)
          gnu_field_list = chainon (gnu_field_list, gnu_field);

        /* Similarly, if this is the _Controller field, put it before the
           other fields except for the _Tag or _Parent field.  */
        else if (gnat_name == Name_uController && gnu_last)
          {
            DECL_CHAIN (gnu_field) = DECL_CHAIN (gnu_last);
            DECL_CHAIN (gnu_last) = gnu_field;
          }

        /* Otherwise, put it after the other fields.  */
        else
          {
            DECL_CHAIN (gnu_field) = gnu_field_list;
            gnu_field_list = gnu_field;
            if (!gnu_last)
              gnu_last = gnu_field;
            if (TREE_CODE (gnu_pos) != INTEGER_CST)
              all_constant_pos = false;
          }

        /* For a stored discriminant in a derived type, replace the field.  */
        if (!is_subtype && Ekind (gnat_field) == E_Discriminant)
          {
            tree gnu_ref = get_gnu_tree (gnat_field);
            TREE_OPERAND (gnu_ref, 1) = gnu_field;
          }
        else
          save_gnu_tree (gnat_field, gnu_field, false);
      }

  /* If there is a variant list, a selected variant and the fields all have a
     constant position, put them in order of increasing position to match that
     of constant CONSTRUCTORs.  Likewise if there is no variant list but a REP
     part, since the latter has been flattened in the process.  */
  if ((gnu_variant_list.exists () ? selected_variant : gnu_rep_part != NULL)
      && all_constant_pos)
    {
      const int len = list_length (gnu_field_list);
      tree *field_arr = XALLOCAVEC (tree, len), t = gnu_field_list;

      for (int i = 0; t; t = DECL_CHAIN (t), i++)
        field_arr[i] = t;

      qsort (field_arr, len, sizeof (tree), compare_field_bitpos);

      gnu_field_list = NULL_TREE;
      for (int i = 0; i < len; i++)
        {
          DECL_CHAIN (field_arr[i]) = gnu_field_list;
          gnu_field_list = field_arr[i];
        }
    }

  /* If there is a variant list and no selected variant, we need to create the
     nest of variant parts from the old nest.  */
  else if (gnu_variant_list.exists () && !selected_variant)
    {
      tree new_variant_part
        = create_variant_part_from (gnu_variant_part, gnu_variant_list,
                                    gnu_new_type, gnu_pos_list,
                                    gnu_subst_list, debug_info_p);
      DECL_CHAIN (new_variant_part) = gnu_field_list;
      gnu_field_list = new_variant_part;
    }

  gnu_variant_list.release ();
  gnu_subst_list.release ();

  gnu_field_list = nreverse (gnu_field_list);

  /* If NEW_TYPE is a subtype, it inherits all the attributes from OLD_TYPE.
     Otherwise sizes and alignment must be computed independently.  */
  if (is_subtype)
    {
      finish_record_type (gnu_new_type, gnu_field_list, 2, debug_info_p);
      compute_record_mode (gnu_new_type);
    }
  else
    finish_record_type (gnu_new_type, gnu_field_list, 1, debug_info_p);

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

/* Associate to GNU_TYPE, the translation of GNAT_ENTITY, which is
   the implementation type of a packed array type (Is_Packed_Array_Impl_Type),
   the original array type if it has been translated.  This association is a
   parallel type for GNAT encodings or a debug type for standard DWARF.  Note
   that for standard DWARF, we also want to get the original type name.  */

static void
associate_original_type_to_packed_array (tree gnu_type, Entity_Id gnat_entity)
{
  Entity_Id gnat_original_array_type
    = Underlying_Type (Original_Array_Type (gnat_entity));
  tree gnu_original_array_type;

  if (!present_gnu_tree (gnat_original_array_type))
    return;

  gnu_original_array_type = gnat_to_gnu_type (gnat_original_array_type);

  if (TYPE_IS_DUMMY_P (gnu_original_array_type))
    return;

  if (gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
    {
      tree original_name = TYPE_NAME (gnu_original_array_type);

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

      SET_TYPE_ORIGINAL_PACKED_ARRAY (gnu_type, gnu_original_array_type);
      TYPE_NAME (gnu_type) = original_name;
    }
  else
    add_parallel_type (gnu_type, gnu_original_array_type);
}
\f
/* Given a type T, a FIELD_DECL F, and a replacement value R, return an
   equivalent type with adjusted size expressions where all occurrences
   of references to F in a PLACEHOLDER_EXPR have been replaced by R.

   The function doesn't update the layout of the type, i.e. it assumes
   that the substitution is purely formal.  That's why the replacement
   value R must itself contain a PLACEHOLDER_EXPR.  */

tree
substitute_in_type (tree t, tree f, tree r)
{
  tree nt;

  gcc_assert (CONTAINS_PLACEHOLDER_P (r));

  switch (TREE_CODE (t))
    {
    case INTEGER_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
    case REAL_TYPE:

      /* First the domain types of arrays.  */
      if (CONTAINS_PLACEHOLDER_P (TYPE_GCC_MIN_VALUE (t))
          || CONTAINS_PLACEHOLDER_P (TYPE_GCC_MAX_VALUE (t)))
        {
          tree low = SUBSTITUTE_IN_EXPR (TYPE_GCC_MIN_VALUE (t), f, r);
          tree high = SUBSTITUTE_IN_EXPR (TYPE_GCC_MAX_VALUE (t), f, r);

          if (low == TYPE_GCC_MIN_VALUE (t) && high == TYPE_GCC_MAX_VALUE (t))
            return t;

          nt = copy_type (t);
          TYPE_GCC_MIN_VALUE (nt) = low;
          TYPE_GCC_MAX_VALUE (nt) = high;

          if (TREE_CODE (t) == INTEGER_TYPE && TYPE_INDEX_TYPE (t))
            SET_TYPE_INDEX_TYPE
              (nt, substitute_in_type (TYPE_INDEX_TYPE (t), f, r));

          return nt;
        }

      /* Then the subtypes.  */
      if (CONTAINS_PLACEHOLDER_P (TYPE_RM_MIN_VALUE (t))
          || CONTAINS_PLACEHOLDER_P (TYPE_RM_MAX_VALUE (t)))
        {
          tree low = SUBSTITUTE_IN_EXPR (TYPE_RM_MIN_VALUE (t), f, r);
          tree high = SUBSTITUTE_IN_EXPR (TYPE_RM_MAX_VALUE (t), f, r);

          if (low == TYPE_RM_MIN_VALUE (t) && high == TYPE_RM_MAX_VALUE (t))
            return t;

          nt = copy_type (t);
          SET_TYPE_RM_MIN_VALUE (nt, low);
          SET_TYPE_RM_MAX_VALUE (nt, high);

          return nt;
        }

      return t;

    case COMPLEX_TYPE:
      nt = substitute_in_type (TREE_TYPE (t), f, r);
      if (nt == TREE_TYPE (t))
        return t;

      return build_complex_type (nt);

    case FUNCTION_TYPE:
      /* These should never show up here.  */
      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;

        nt = build_nonshared_array_type (component, domain);
        SET_TYPE_ALIGN (nt, TYPE_ALIGN (t));
        TYPE_USER_ALIGN (nt) = TYPE_USER_ALIGN (t);
        SET_TYPE_MODE (nt, TYPE_MODE (t));
        TYPE_SIZE (nt) = SUBSTITUTE_IN_EXPR (TYPE_SIZE (t), f, r);
        TYPE_SIZE_UNIT (nt) = SUBSTITUTE_IN_EXPR (TYPE_SIZE_UNIT (t), f, r);
        TYPE_MULTI_ARRAY_P (nt) = TYPE_MULTI_ARRAY_P (t);
        TYPE_CONVENTION_FORTRAN_P (nt) = TYPE_CONVENTION_FORTRAN_P (t);
        if (TYPE_REVERSE_STORAGE_ORDER (t))
          set_reverse_storage_order_on_array_type (nt);
        if (TYPE_NONALIASED_COMPONENT (t))
          set_nonaliased_component_on_array_type (nt);
        return nt;
      }

    case RECORD_TYPE:
    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      {
        bool changed_field = false;
        tree field;

        /* 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.  */
        nt = copy_type (t);
        TYPE_FIELDS (nt) = NULL_TREE;

        for (field = TYPE_FIELDS (t); field; field = DECL_CHAIN (field))
          {
            tree new_field = copy_node (field), new_n;

            new_n = substitute_in_type (TREE_TYPE (field), f, r);
            if (new_n != TREE_TYPE (field))
              {
                TREE_TYPE (new_field) = new_n;
                changed_field = true;
              }

            new_n = SUBSTITUTE_IN_EXPR (DECL_FIELD_OFFSET (field), f, r);
            if (new_n != DECL_FIELD_OFFSET (field))
              {
                DECL_FIELD_OFFSET (new_field) = new_n;
                changed_field = true;
              }

            /* Do the substitution inside the qualifier, if any.  */
            if (TREE_CODE (t) == QUAL_UNION_TYPE)
              {
                new_n = SUBSTITUTE_IN_EXPR (DECL_QUALIFIER (field), f, r);
                if (new_n != DECL_QUALIFIER (field))
                  {
                    DECL_QUALIFIER (new_field) = new_n;
                    changed_field = true;
                  }
              }

            DECL_CONTEXT (new_field) = nt;
            SET_DECL_ORIGINAL_FIELD_TO_FIELD (new_field, field);

            DECL_CHAIN (new_field) = TYPE_FIELDS (nt);
            TYPE_FIELDS (nt) = new_field;
          }

        if (!changed_field)
          return t;

        TYPE_FIELDS (nt) = nreverse (TYPE_FIELDS (nt));
        TYPE_SIZE (nt) = SUBSTITUTE_IN_EXPR (TYPE_SIZE (t), f, r);
        TYPE_SIZE_UNIT (nt) = SUBSTITUTE_IN_EXPR (TYPE_SIZE_UNIT (t), f, r);
        SET_TYPE_ADA_SIZE (nt, SUBSTITUTE_IN_EXPR (TYPE_ADA_SIZE (t), f, r));
        return nt;
      }

    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 integral types, we store the RM size explicitly.  */
  if (INTEGRAL_TYPE_P (gnu_type) && TYPE_RM_SIZE (gnu_type))
    return TYPE_RM_SIZE (gnu_type);

  /* Return the RM size of the actual data plus the size of the template.  */
  if (TREE_CODE (gnu_type) == RECORD_TYPE
      && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
    return
      size_binop (PLUS_EXPR,
                  rm_size (TREE_TYPE (DECL_CHAIN (TYPE_FIELDS (gnu_type)))),
                  DECL_SIZE (TYPE_FIELDS (gnu_type)));

  /* For record or union types, we store the size explicitly.  */
  if (RECORD_OR_UNION_TYPE_P (gnu_type)
      && !TYPE_FAT_POINTER_P (gnu_type)
      && TYPE_ADA_SIZE (gnu_type))
    return TYPE_ADA_SIZE (gnu_type);

  /* For other types, this is just the size.  */
  return TYPE_SIZE (gnu_type);
}
\f
/* 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.  */

static const char *
get_entity_char (Entity_Id gnat_entity)
{
  Get_Encoded_Name (gnat_entity);
  return ggc_strdup (Name_Buffer);
}

tree
get_entity_name (Entity_Id gnat_entity)
{
  Get_Encoded_Name (gnat_entity);
  return get_identifier_with_length (Name_Buffer, Name_Len);
}

/* 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)
{
  const Entity_Kind kind = Ekind (gnat_entity);
  const bool has_suffix = (suffix != NULL);
  String_Template temp = {1, has_suffix ? strlen (suffix) : 0};
  String_Pointer sp = {suffix, &temp};

  Get_External_Name (gnat_entity, has_suffix, sp);

  /* A variable using the Stdcall convention lives in a DLL.  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 int len = strlen (STDCALL_PREFIX) + Name_Len;
      char *new_name = (char *) alloca (len + 1);
      strcpy (new_name, STDCALL_PREFIX);
      strcat (new_name, Name_Buffer);
      return get_identifier_with_length (new_name, len);
    }

  return get_identifier_with_length (Name_Buffer, Name_Len);
}

/* Given GNU_NAME, an IDENTIFIER_NODE containing a name and SUFFIX, a
   string, return a new IDENTIFIER_NODE that is the concatenation of
   the name followed by "___" and the specified suffix.  */

tree
concat_name (tree gnu_name, const char *suffix)
{
  const int len = IDENTIFIER_LENGTH (gnu_name) + 3 + strlen (suffix);
  char *new_name = (char *) alloca (len + 1);
  strcpy (new_name, IDENTIFIER_POINTER (gnu_name));
  strcat (new_name, "___");
  strcat (new_name, suffix);
  return get_identifier_with_length (new_name, len);
}

/* Initialize data structures of the decl.c module.  */

void
init_gnat_decl (void)
{
  /* Initialize the cache of annotated values.  */
  annotate_value_cache = hash_table<value_annotation_hasher>::create_ggc (512);

  /* Initialize the association of dummy types with subprograms.  */
  dummy_to_subprog_map = hash_table<dummy_type_hasher>::create_ggc (512);
}

/* Destroy data structures of the decl.c module.  */

void
destroy_gnat_decl (void)
{
  /* Destroy the cache of annotated values.  */
  annotate_value_cache->empty ();
  annotate_value_cache = NULL;

  /* Destroy the association of dummy types with subprograms.  */
  dummy_to_subprog_map->empty ();
  dummy_to_subprog_map = NULL;
}

#include "gt-ada-decl.h"