[pf3gnuchains/gcc-fork.git] / gcc / ada / trans.c

/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                                T R A N S                                 *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *          Copyright (C) 1992-2008, Free Software Foundation, Inc.         *
 *                                                                          *
 * GNAT is free software;  you can  redistribute it  and/or modify it under *
 * terms of the  GNU General Public License as published  by the Free Soft- *
 * ware  Foundation;  either version 2,  or (at your option) any later ver- *
 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
 * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License *
 * for  more details.  You should have  received  a copy of the GNU General *
 * Public License  distributed with GNAT;  see file COPYING.  If not, write *
 * to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, *
 * Boston, MA 02110-1301, USA.                                              *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "real.h"
#include "flags.h"
#include "toplev.h"
#include "rtl.h"
#include "expr.h"
#include "ggc.h"
#include "cgraph.h"
#include "function.h"
#include "except.h"
#include "debug.h"
#include "output.h"
#include "tree-gimple.h"
#include "ada.h"
#include "types.h"
#include "atree.h"
#include "elists.h"
#include "namet.h"
#include "nlists.h"
#include "snames.h"
#include "stringt.h"
#include "uintp.h"
#include "urealp.h"
#include "fe.h"
#include "sinfo.h"
#include "einfo.h"
#include "ada-tree.h"
#include "gigi.h"
#include "adadecode.h"

#include "dwarf2.h"
#include "dwarf2out.h"

/* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
   for fear of running out of stack space.  If we need more, we use xmalloc
   instead.  */
#define ALLOCA_THRESHOLD 1000

/* Let code below know whether we are targetting VMS without need of
   intrusive preprocessor directives.  */
#ifndef TARGET_ABI_OPEN_VMS
#define TARGET_ABI_OPEN_VMS 0
#endif

extern char *__gnat_to_canonical_file_spec (char *);

int max_gnat_nodes;
int number_names;
int number_files;
struct Node *Nodes_Ptr;
Node_Id *Next_Node_Ptr;
Node_Id *Prev_Node_Ptr;
struct Elist_Header *Elists_Ptr;
struct Elmt_Item *Elmts_Ptr;
struct String_Entry *Strings_Ptr;
Char_Code *String_Chars_Ptr;
struct List_Header *List_Headers_Ptr;

/* Current filename without path. */
const char *ref_filename;

/* If true, then gigi is being called on an analyzed but unexpanded
   tree, and the only purpose of the call is to properly annotate
   types with representation information. */
bool type_annotate_only;

/* When not optimizing, we cache the 'First, 'Last and 'Length attributes
   of unconstrained array IN parameters to avoid emitting a great deal of
   redundant instructions to recompute them each time.  */
struct parm_attr GTY (())
{
  int id; /* GTY doesn't like Entity_Id.  */
  int dim;
  tree first;
  tree last;
  tree length;
};

typedef struct parm_attr *parm_attr;

DEF_VEC_P(parm_attr);
DEF_VEC_ALLOC_P(parm_attr,gc);

struct language_function GTY(())
{
  VEC(parm_attr,gc) *parm_attr_cache;
};

#define f_parm_attr_cache \
  DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache

/* A structure used to gather together information about a statement group.
   We use this to gather related statements, for example the "then" part
   of a IF.  In the case where it represents a lexical scope, we may also
   have a BLOCK node corresponding to it and/or cleanups.  */

struct stmt_group GTY((chain_next ("%h.previous"))) {
  struct stmt_group *previous;  /* Previous code group.  */
  tree stmt_list;               /* List of statements for this code group. */
  tree block;                   /* BLOCK for this code group, if any. */
  tree cleanups;                /* Cleanups for this code group, if any.  */
};

static GTY(()) struct stmt_group *current_stmt_group;

/* List of unused struct stmt_group nodes.  */
static GTY((deletable)) struct stmt_group *stmt_group_free_list;

/* A structure used to record information on elaboration procedures
   we've made and need to process.

   ??? gnat_node should be Node_Id, but gengtype gets confused.  */

struct elab_info GTY((chain_next ("%h.next"))) {
  struct elab_info *next;       /* Pointer to next in chain. */
  tree elab_proc;               /* Elaboration procedure.  */
  int gnat_node;                /* The N_Compilation_Unit.  */
};

static GTY(()) struct elab_info *elab_info_list;

/* Free list of TREE_LIST nodes used for stacks.  */
static GTY((deletable)) tree gnu_stack_free_list;

/* List of TREE_LIST nodes representing a stack of exception pointer
   variables.  TREE_VALUE is the VAR_DECL that stores the address of
   the raised exception.  Nonzero means we are in an exception
   handler.  Not used in the zero-cost case.  */
static GTY(()) tree gnu_except_ptr_stack;

/* List of TREE_LIST nodes used to store the current elaboration procedure
   decl.  TREE_VALUE is the decl.  */
static GTY(()) tree gnu_elab_proc_stack;

/* Variable that stores a list of labels to be used as a goto target instead of
   a return in some functions.  See processing for N_Subprogram_Body.  */
static GTY(()) tree gnu_return_label_stack;

/* List of TREE_LIST nodes representing a stack of LOOP_STMT nodes.
   TREE_VALUE of each entry is the label of the corresponding LOOP_STMT.  */
static GTY(()) tree gnu_loop_label_stack;

/* List of TREE_LIST nodes representing labels for switch statements.
   TREE_VALUE of each entry is the label at the end of the switch.  */
static GTY(()) tree gnu_switch_label_stack;

/* List of TREE_LIST nodes containing the stacks for N_{Push,Pop}_*_Label.  */
static GTY(()) tree gnu_constraint_error_label_stack;
static GTY(()) tree gnu_storage_error_label_stack;
static GTY(()) tree gnu_program_error_label_stack;

/* Map GNAT tree codes to GCC tree codes for simple expressions.  */
static enum tree_code gnu_codes[Number_Node_Kinds];

/* Current node being treated, in case abort called.  */
Node_Id error_gnat_node;

static void init_code_table (void);
static void Compilation_Unit_to_gnu (Node_Id);
static void record_code_position (Node_Id);
static void insert_code_for (Node_Id);
static void add_cleanup (tree, Node_Id);
static tree unshare_save_expr (tree *, int *, void *);
static void add_stmt_list (List_Id);
static void push_exception_label_stack (tree *, Entity_Id);
static tree build_stmt_group (List_Id, bool);
static void push_stack (tree *, tree, tree);
static void pop_stack (tree *);
static enum gimplify_status gnat_gimplify_stmt (tree *);
static void elaborate_all_entities (Node_Id);
static void process_freeze_entity (Node_Id);
static void process_inlined_subprograms (Node_Id);
static void process_decls (List_Id, List_Id, Node_Id, bool, bool);
static tree emit_range_check (tree, Node_Id);
static tree emit_index_check (tree, tree, tree, tree);
static tree emit_check (tree, tree, int);
static tree convert_with_check (Entity_Id, tree, bool, bool, bool);
static bool smaller_packable_type_p (tree, tree);
static bool addressable_p (tree, tree);
static tree assoc_to_constructor (Entity_Id, Node_Id, tree);
static tree extract_values (tree, tree);
static tree pos_to_constructor (Node_Id, tree, Entity_Id);
static tree maybe_implicit_deref (tree);
static tree gnat_stabilize_reference (tree, bool);
static tree gnat_stabilize_reference_1 (tree, bool);
static void set_expr_location_from_node (tree, Node_Id);
static int lvalue_required_p (Node_Id, tree, int);

/* Hooks for debug info back-ends, only supported and used in a restricted set
   of configurations.  */
static const char *extract_encoding (const char *) ATTRIBUTE_UNUSED;
static const char *decode_name (const char *) ATTRIBUTE_UNUSED;
\f
/* This is the main program of the back-end.  It sets up all the table
   structures and then generates code.  */

void
gigi (Node_Id gnat_root, int max_gnat_node, int number_name,
      struct Node *nodes_ptr, Node_Id *next_node_ptr, Node_Id *prev_node_ptr,
      struct Elist_Header *elists_ptr, struct Elmt_Item *elmts_ptr,
      struct String_Entry *strings_ptr, Char_Code *string_chars_ptr,
      struct List_Header *list_headers_ptr, Nat number_file,
      struct File_Info_Type *file_info_ptr,
      Entity_Id standard_integer, Entity_Id standard_long_long_float,
      Entity_Id standard_exception_type, Int gigi_operating_mode)
{
  tree gnu_standard_long_long_float;
  tree gnu_standard_exception_type;
  struct elab_info *info;
  int i;

  max_gnat_nodes = max_gnat_node;
  number_names = number_name;
  number_files = number_file;
  Nodes_Ptr = nodes_ptr;
  Next_Node_Ptr = next_node_ptr;
  Prev_Node_Ptr = prev_node_ptr;
  Elists_Ptr = elists_ptr;
  Elmts_Ptr = elmts_ptr;
  Strings_Ptr = strings_ptr;
  String_Chars_Ptr = string_chars_ptr;
  List_Headers_Ptr = list_headers_ptr;

  type_annotate_only = (gigi_operating_mode == 1);

  for (i = 0; i < number_files; i++)
    {
      /* Use the identifier table to make a permanent copy of the filename as
         the name table gets reallocated after Gigi returns but before all the
         debugging information is output.  The __gnat_to_canonical_file_spec
         call translates filenames from pragmas Source_Reference that contain
         host style syntax not understood by gdb. */
      const char *filename
        = IDENTIFIER_POINTER
           (get_identifier
            (__gnat_to_canonical_file_spec
             (Get_Name_String (file_info_ptr[i].File_Name))));

      /* We rely on the order isomorphism between files and line maps.  */
      gcc_assert ((int) line_table->used == i);

      /* We create the line map for a source file at once, with a fixed number
         of columns chosen to avoid jumping over the next power of 2.  */
      linemap_add (line_table, LC_ENTER, 0, filename, 1);
      linemap_line_start (line_table, file_info_ptr[i].Num_Source_Lines, 252);
      linemap_position_for_column (line_table, 252 - 1);
      linemap_add (line_table, LC_LEAVE, 0, NULL, 0);
    }

  /* Initialize ourselves.  */
  init_code_table ();
  init_gnat_to_gnu ();
  gnat_compute_largest_alignment ();
  init_dummy_type ();

  /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
     errors.  */
  if (type_annotate_only)
    {
      TYPE_SIZE (void_type_node) = bitsize_zero_node;
      TYPE_SIZE_UNIT (void_type_node) = size_zero_node;
    }

  /* If the GNU type extensions to DWARF are available, setup the hooks.  */
#if defined (DWARF2_DEBUGGING_INFO) && defined (DWARF2_GNU_TYPE_EXTENSIONS)
  /* We condition the name demangling and the generation of type encoding
     strings on -gdwarf+ and always set descriptive types on.  */
  if (use_gnu_debug_info_extensions)
    {
      dwarf2out_set_type_encoding_func (extract_encoding);
      dwarf2out_set_demangle_name_func (decode_name);
    }
  dwarf2out_set_descriptive_type_func (get_parallel_type);
#endif

  /* Enable GNAT stack checking method if needed */
  if (!Stack_Check_Probes_On_Target)
    set_stack_check_libfunc (gen_rtx_SYMBOL_REF (Pmode, "_gnat_stack_check"));

  /* Give names and make TYPE_DECLs for common types.  */
  create_type_decl (get_identifier (SIZE_TYPE), sizetype,
                    NULL, false, true, Empty);
  create_type_decl (get_identifier ("integer"), integer_type_node,
                    NULL, false, true, Empty);
  create_type_decl (get_identifier ("unsigned char"), char_type_node,
                    NULL, false, true, Empty);
  create_type_decl (get_identifier ("long integer"), long_integer_type_node,
                    NULL, false, true, Empty);

  /* Save the type we made for integer as the type for Standard.Integer.
     Then make the rest of the standard types.  Note that some of these
     may be subtypes.  */
  save_gnu_tree (Base_Type (standard_integer), TYPE_NAME (integer_type_node),
                 false);

  gnu_except_ptr_stack = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE);
  gnu_constraint_error_label_stack
    = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE);
  gnu_storage_error_label_stack = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE);
  gnu_program_error_label_stack = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE);

  gnu_standard_long_long_float
    = gnat_to_gnu_entity (Base_Type (standard_long_long_float), NULL_TREE, 0);
  gnu_standard_exception_type
    = gnat_to_gnu_entity (Base_Type (standard_exception_type),  NULL_TREE, 0);

  init_gigi_decls (gnu_standard_long_long_float, gnu_standard_exception_type);

  /* Process any Pragma Ident for the main unit.  */
#ifdef ASM_OUTPUT_IDENT
  if (Present (Ident_String (Main_Unit)))
    ASM_OUTPUT_IDENT
      (asm_out_file,
       TREE_STRING_POINTER (gnat_to_gnu (Ident_String (Main_Unit))));
#endif

  /* If we are using the GCC exception mechanism, let GCC know.  */
  if (Exception_Mechanism == Back_End_Exceptions)
    gnat_init_gcc_eh ();

  gcc_assert (Nkind (gnat_root) == N_Compilation_Unit);
  start_stmt_group ();
  Compilation_Unit_to_gnu (gnat_root);

  /* Now see if we have any elaboration procedures to deal with. */
  for (info = elab_info_list; info; info = info->next)
    {
      tree gnu_body = DECL_SAVED_TREE (info->elab_proc);
      tree gnu_stmts;

      /* Unshare SAVE_EXPRs between subprograms.  These are not unshared by
         the gimplifier for obvious reasons, but it turns out that we need to
         unshare them for the global level because of SAVE_EXPRs made around
         checks for global objects and around allocators for global objects
         of variable size, in order to prevent node sharing in the underlying
         expression.  Note that this implicitly assumes that the SAVE_EXPR
         nodes themselves are not shared between subprograms, which would be
         an upstream bug for which we would not change the outcome.  */
      walk_tree_without_duplicates (&gnu_body, unshare_save_expr, NULL);

      /* Set the current function to be the elaboration procedure and gimplify
         what we have.  */
      current_function_decl = info->elab_proc;
      gimplify_body (&gnu_body, info->elab_proc, true);

      /* We should have a BIND_EXPR, but it may or may not have any statements
         in it.  If it doesn't have any, we have nothing to do.  */
      gnu_stmts = gnu_body;
      if (TREE_CODE (gnu_stmts) == BIND_EXPR)
        gnu_stmts = BIND_EXPR_BODY (gnu_stmts);

      /* If there are no statements, there is no elaboration code.  */
      if (!gnu_stmts || !STATEMENT_LIST_HEAD (gnu_stmts))
        {
          Set_Has_No_Elaboration_Code (info->gnat_node, 1);
          cgraph_remove_node (cgraph_node (info->elab_proc));
        }
      else
        {
          /* Otherwise, compile the function.  Note that we'll be gimplifying
             it twice, but that's fine for the nodes we use.  */
          begin_subprog_body (info->elab_proc);
          end_subprog_body (gnu_body);
        }
    }

  /* We cannot track the location of errors past this point.  */
  error_gnat_node = Empty;
}
\f
/* Return a positive value if an lvalue is required for GNAT_NODE.
   GNU_TYPE is the type that will be used for GNAT_NODE in the
   translated GNU tree.  ALIASED indicates whether the underlying
   object represented by GNAT_NODE is aliased in the Ada sense.

   The function climbs up the GNAT tree starting from the node and
   returns 1 upon encountering a node that effectively requires an
   lvalue downstream.  It returns int instead of bool to facilitate
   usage in non purely binary logic contexts.  */

static int
lvalue_required_p (Node_Id gnat_node, tree gnu_type, int aliased)
{
  Node_Id gnat_parent = Parent (gnat_node), gnat_temp;

  switch (Nkind (gnat_parent))
    {
    case N_Reference:
      return 1;

    case N_Attribute_Reference:
      {
        unsigned char id = Get_Attribute_Id (Attribute_Name (gnat_parent));
        return id == Attr_Address
               || id == Attr_Access
               || id == Attr_Unchecked_Access
               || id == Attr_Unrestricted_Access;
      }

    case N_Parameter_Association:
    case N_Function_Call:
    case N_Procedure_Call_Statement:
      return (must_pass_by_ref (gnu_type) || default_pass_by_ref (gnu_type));

    case N_Indexed_Component:
      /* Only the array expression can require an lvalue.  */
      if (Prefix (gnat_parent) != gnat_node)
        return 0;

      /* ??? Consider that referencing an indexed component with a
         non-constant index forces the whole aggregate to memory.
         Note that N_Integer_Literal is conservative, any static
         expression in the RM sense could probably be accepted.  */
      for (gnat_temp = First (Expressions (gnat_parent));
           Present (gnat_temp);
           gnat_temp = Next (gnat_temp))
        if (Nkind (gnat_temp) != N_Integer_Literal)
          return 1;

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

    case N_Slice:
      /* Only the array expression can require an lvalue.  */
      if (Prefix (gnat_parent) != gnat_node)
        return 0;

      aliased |= Has_Aliased_Components (Etype (gnat_node));
      return lvalue_required_p (gnat_parent, gnu_type, aliased);

    case N_Selected_Component:
      aliased |= Is_Aliased (Entity (Selector_Name (gnat_parent)));
      return lvalue_required_p (gnat_parent, gnu_type, aliased);

    case N_Object_Renaming_Declaration:
      /* We need to make a real renaming only if the constant object is
         aliased or if we may use a renaming pointer; otherwise we can
         optimize and return the rvalue.  We make an exception if the object
         is an identifier since in this case the rvalue can be propagated
         attached to the CONST_DECL.  */
      return (aliased != 0
              /* This should match the constant case of the renaming code.  */
              || Is_Composite_Type (Etype (Name (gnat_parent)))
              || Nkind (Name (gnat_parent)) == N_Identifier);

    default:
      return 0;
    }

  gcc_unreachable ();
}

/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
   to a GCC tree, which is returned.  GNU_RESULT_TYPE_P is a pointer
   to where we should place the result type.  */

static tree
Identifier_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p)
{
  Node_Id gnat_temp, gnat_temp_type;
  tree gnu_result, gnu_result_type;

  /* Whether we should require an lvalue for GNAT_NODE.  Needed in
     specific circumstances only, so evaluated lazily.  < 0 means
     unknown, > 0 means known true, 0 means known false.  */
  int require_lvalue = -1;

  /* If GNAT_NODE is a constant, whether we should use the initialization
     value instead of the constant entity, typically for scalars with an
     address clause when the parent doesn't require an lvalue.  */
  bool use_constant_initializer = false;

  /* If the Etype of this node does not equal the Etype of the Entity,
     something is wrong with the entity map, probably in generic
     instantiation. However, this does not apply to types. Since we sometime
     have strange Ekind's, just do this test for objects. Also, if the Etype of
     the Entity is private, the Etype of the N_Identifier is allowed to be the
     full type and also we consider a packed array type to be the same as the
     original type. Similarly, a class-wide type is equivalent to a subtype of
     itself. Finally, if the types are Itypes, one may be a copy of the other,
     which is also legal.  */
  gnat_temp = (Nkind (gnat_node) == N_Defining_Identifier
               ? gnat_node : Entity (gnat_node));
  gnat_temp_type = Etype (gnat_temp);

  gcc_assert (Etype (gnat_node) == gnat_temp_type
              || (Is_Packed (gnat_temp_type)
                  && Etype (gnat_node) == Packed_Array_Type (gnat_temp_type))
              || (Is_Class_Wide_Type (Etype (gnat_node)))
              || (IN (Ekind (gnat_temp_type), Private_Kind)
                  && Present (Full_View (gnat_temp_type))
                  && ((Etype (gnat_node) == Full_View (gnat_temp_type))
                      || (Is_Packed (Full_View (gnat_temp_type))
                          && (Etype (gnat_node)
                              == Packed_Array_Type (Full_View
                                                    (gnat_temp_type))))))
              || (Is_Itype (Etype (gnat_node)) && Is_Itype (gnat_temp_type))
              || !(Ekind (gnat_temp) == E_Variable
                   || Ekind (gnat_temp) == E_Component
                   || Ekind (gnat_temp) == E_Constant
                   || Ekind (gnat_temp) == E_Loop_Parameter
                   || IN (Ekind (gnat_temp), Formal_Kind)));

  /* If this is a reference to a deferred constant whose partial view is an
     unconstrained private type, the proper type is on the full view of the
     constant, not on the full view of the type, which may be unconstrained.

     This may be a reference to a type, for example in the prefix of the
     attribute Position, generated for dispatching code (see Make_DT in
     exp_disp,adb). In that case we need the type itself, not is parent,
     in particular if it is a derived type  */
  if (Is_Private_Type (gnat_temp_type)
      && Has_Unknown_Discriminants (gnat_temp_type)
      && Ekind (gnat_temp) == E_Constant
      && Present (Full_View (gnat_temp)))
    {
      gnat_temp = Full_View (gnat_temp);
      gnat_temp_type = Etype (gnat_temp);
    }
  else
    {
      /* We want to use the Actual_Subtype if it has already been elaborated,
         otherwise the Etype.  Avoid using Actual_Subtype for packed arrays to
         simplify things.  */
      if ((Ekind (gnat_temp) == E_Constant
           || Ekind (gnat_temp) == E_Variable || Is_Formal (gnat_temp))
          && !(Is_Array_Type (Etype (gnat_temp))
               && Present (Packed_Array_Type (Etype (gnat_temp))))
          && Present (Actual_Subtype (gnat_temp))
          && present_gnu_tree (Actual_Subtype (gnat_temp)))
        gnat_temp_type = Actual_Subtype (gnat_temp);
      else
        gnat_temp_type = Etype (gnat_node);
    }

  /* Expand the type of this identifier first, in case it is an enumeral
     literal, which only get made when the type is expanded.  There is no
     order-of-elaboration issue here.  */
  gnu_result_type = get_unpadded_type (gnat_temp_type);

  /* If this is a non-imported scalar constant with an address clause,
     retrieve the value instead of a pointer to be dereferenced unless
     an lvalue is required.  This is generally more efficient and actually
     required if this is a static expression because it might be used
     in a context where a dereference is inappropriate, such as a case
     statement alternative or a record discriminant.  There is no possible
     volatile-ness short-circuit here since Volatile constants must be imported
     per C.6. */
  if (Ekind (gnat_temp) == E_Constant && Is_Scalar_Type (gnat_temp_type)
      && !Is_Imported (gnat_temp)
      && Present (Address_Clause (gnat_temp)))
    {
      require_lvalue = lvalue_required_p (gnat_node, gnu_result_type,
                                          Is_Aliased (gnat_temp));
      use_constant_initializer = !require_lvalue;
    }

  if (use_constant_initializer)
    {
      /* If this is a deferred constant, the initializer is attached to
         the full view.  */
      if (Present (Full_View (gnat_temp)))
        gnat_temp = Full_View (gnat_temp);

      gnu_result = gnat_to_gnu (Expression (Declaration_Node (gnat_temp)));
    }
  else
    gnu_result = gnat_to_gnu_entity (gnat_temp, NULL_TREE, 0);

  /* If we are in an exception handler, force this variable into memory to
     ensure optimization does not remove stores that appear redundant but are
     actually needed in case an exception occurs.

     ??? Note that we need not do this if the variable is declared within the
     handler, only if it is referenced in the handler and declared in an
     enclosing block, but we have no way of testing that right now.

     ??? We used to essentially set the TREE_ADDRESSABLE flag on the variable
     here, but it can now be removed by the Tree aliasing machinery if the
     address of the variable is never taken.  All we can do is to make the
     variable volatile, which might incur the generation of temporaries just
     to access the memory in some circumstances.  This can be avoided for
     variables of non-constant size because they are automatically allocated
     to memory.  There might be no way of allocating a proper temporary for
     them in any case.  We only do this for SJLJ though.  */
  if (TREE_VALUE (gnu_except_ptr_stack)
      && TREE_CODE (gnu_result) == VAR_DECL
      && TREE_CODE (DECL_SIZE_UNIT (gnu_result)) == INTEGER_CST)
    TREE_THIS_VOLATILE (gnu_result) = TREE_SIDE_EFFECTS (gnu_result) = 1;

  /* Some objects (such as parameters passed by reference, globals of
     variable size, and renamed objects) actually represent the address
     of the object.  In that case, we must do the dereference.  Likewise,
     deal with parameters to foreign convention subprograms.  */
  if (DECL_P (gnu_result)
      && (DECL_BY_REF_P (gnu_result)
          || (TREE_CODE (gnu_result) == PARM_DECL
              && DECL_BY_COMPONENT_PTR_P (gnu_result))))
    {
      bool ro = DECL_POINTS_TO_READONLY_P (gnu_result);
      tree renamed_obj;

      if (TREE_CODE (gnu_result) == PARM_DECL
          && DECL_BY_COMPONENT_PTR_P (gnu_result))
        gnu_result
          = build_unary_op (INDIRECT_REF, NULL_TREE,
                            convert (build_pointer_type (gnu_result_type),
                                     gnu_result));

      /* If it's a renaming pointer and we are at the right binding level,
         we can reference the renamed object directly, since the renamed
         expression has been protected against multiple evaluations.  */
      else if (TREE_CODE (gnu_result) == VAR_DECL
               && (renamed_obj = DECL_RENAMED_OBJECT (gnu_result)) != 0
               && (! DECL_RENAMING_GLOBAL_P (gnu_result)
                   || global_bindings_p ()))
        gnu_result = renamed_obj;

      /* Return the underlying CST for a CONST_DECL like a few lines below,
         after dereferencing in this case.  */
      else if (TREE_CODE (gnu_result) == CONST_DECL)
        gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE,
                                     DECL_INITIAL (gnu_result));

      else
        gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE, gnu_result);

      TREE_READONLY (gnu_result) = TREE_STATIC (gnu_result) = ro;
    }

  /* The GNAT tree has the type of a function as the type of its result.  Also
     use the type of the result if the Etype is a subtype which is nominally
     unconstrained.  But remove any padding from the resulting type.  */
  if (TREE_CODE (TREE_TYPE (gnu_result)) == FUNCTION_TYPE
      || Is_Constr_Subt_For_UN_Aliased (gnat_temp_type))
    {
      gnu_result_type = TREE_TYPE (gnu_result);
      if (TREE_CODE (gnu_result_type) == RECORD_TYPE
          && TYPE_IS_PADDING_P (gnu_result_type))
        gnu_result_type = TREE_TYPE (TYPE_FIELDS (gnu_result_type));
    }

  /* If we have a constant declaration and its initializer at hand,
     try to return the latter to avoid the need to call fold in lots
     of places and the need of elaboration code if this Id is used as
     an initializer itself.  */
  if (TREE_CONSTANT (gnu_result)
      && DECL_P (gnu_result)
      && DECL_INITIAL (gnu_result))
    {
      tree object
        = (TREE_CODE (gnu_result) == CONST_DECL
           ? DECL_CONST_CORRESPONDING_VAR (gnu_result) : gnu_result);

      /* If there is a corresponding variable, we only want to return
         the CST value if an lvalue is not required.  Evaluate this
         now if we have not already done so.  */
      if (object && require_lvalue < 0)
        require_lvalue = lvalue_required_p (gnat_node, gnu_result_type,
                                            Is_Aliased (gnat_temp));

      if (!object || !require_lvalue)
        gnu_result = unshare_expr (DECL_INITIAL (gnu_result));
    }

  *gnu_result_type_p = gnu_result_type;
  return gnu_result;
}
\f
/* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma.  Return
   any statements we generate.  */

static tree
Pragma_to_gnu (Node_Id gnat_node)
{
  Node_Id gnat_temp;
  tree gnu_result = alloc_stmt_list ();

  /* Check for (and ignore) unrecognized pragma and do nothing if we are just
     annotating types.  */
  if (type_annotate_only
      || !Is_Pragma_Name (Chars (Pragma_Identifier (gnat_node))))
    return gnu_result;

  switch (Get_Pragma_Id (Chars (Pragma_Identifier (gnat_node))))
    {
    case Pragma_Inspection_Point:
      /* Do nothing at top level: all such variables are already viewable.  */
      if (global_bindings_p ())
        break;

      for (gnat_temp = First (Pragma_Argument_Associations (gnat_node));
           Present (gnat_temp);
           gnat_temp = Next (gnat_temp))
        {
          Node_Id gnat_expr = Expression (gnat_temp);
          tree gnu_expr = gnat_to_gnu (gnat_expr);
          int use_address;
          enum machine_mode mode;
          tree asm_constraint = NULL_TREE;
#ifdef ASM_COMMENT_START
          char *comment;
#endif

          if (TREE_CODE (gnu_expr) == UNCONSTRAINED_ARRAY_REF)
            gnu_expr = TREE_OPERAND (gnu_expr, 0);

          /* Use the value only if it fits into a normal register,
             otherwise use the address.  */
          mode = TYPE_MODE (TREE_TYPE (gnu_expr));
          use_address = ((GET_MODE_CLASS (mode) != MODE_INT
                          && GET_MODE_CLASS (mode) != MODE_PARTIAL_INT)
                         || GET_MODE_SIZE (mode) > UNITS_PER_WORD);

          if (use_address)
            gnu_expr = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_expr);

#ifdef ASM_COMMENT_START
          comment = concat (ASM_COMMENT_START,
                            " inspection point: ",
                            Get_Name_String (Chars (gnat_expr)),
                            use_address ? " address" : "",
                            " is in %0",
                            NULL);
          asm_constraint = build_string (strlen (comment), comment);
          free (comment);
#endif
          gnu_expr = build4 (ASM_EXPR, void_type_node,
                             asm_constraint,
                             NULL_TREE,
                             tree_cons
                             (build_tree_list (NULL_TREE,
                                               build_string (1, "g")),
                              gnu_expr, NULL_TREE),
                             NULL_TREE);
          ASM_VOLATILE_P (gnu_expr) = 1;
          set_expr_location_from_node (gnu_expr, gnat_node);
          append_to_statement_list (gnu_expr, &gnu_result);
        }
      break;

    case Pragma_Optimize:
      switch (Chars (Expression
                     (First (Pragma_Argument_Associations (gnat_node)))))
        {
        case Name_Time:  case Name_Space:
          if (optimize == 0)
            post_error ("insufficient -O value?", gnat_node);
          break;

        case Name_Off:
          if (optimize != 0)
            post_error ("must specify -O0?", gnat_node);
          break;

        default:
          gcc_unreachable ();
        }
      break;

    case Pragma_Reviewable:
      if (write_symbols == NO_DEBUG)
        post_error ("must specify -g?", gnat_node);
      break;
    }

  return gnu_result;
}
/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Attribute,
   to a GCC tree, which is returned.  GNU_RESULT_TYPE_P is a pointer to
   where we should place the result type.  ATTRIBUTE is the attribute ID.  */

static tree
Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute)
{
  tree gnu_result = error_mark_node;
  tree gnu_result_type;
  tree gnu_expr;
  bool prefix_unused = false;
  tree gnu_prefix = gnat_to_gnu (Prefix (gnat_node));
  tree gnu_type = TREE_TYPE (gnu_prefix);

  /* If the input is a NULL_EXPR, make a new one.  */
  if (TREE_CODE (gnu_prefix) == NULL_EXPR)
    {
      *gnu_result_type_p = get_unpadded_type (Etype (gnat_node));
      return build1 (NULL_EXPR, *gnu_result_type_p,
                     TREE_OPERAND (gnu_prefix, 0));
    }

  switch (attribute)
    {
    case Attr_Pos:
    case Attr_Val:
      /* These are just conversions until since representation clauses for
         enumerations are handled in the front end.  */
      {
        bool checkp = Do_Range_Check (First (Expressions (gnat_node)));

        gnu_result = gnat_to_gnu (First (Expressions (gnat_node)));
        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        gnu_result = convert_with_check (Etype (gnat_node), gnu_result,
                                         checkp, checkp, true);
      }
      break;

    case Attr_Pred:
    case Attr_Succ:
      /* These just add or subject the constant 1.  Representation clauses for
         enumerations are handled in the front-end.  */
      gnu_expr = gnat_to_gnu (First (Expressions (gnat_node)));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));

      if (Do_Range_Check (First (Expressions (gnat_node))))
        {
          gnu_expr = protect_multiple_eval (gnu_expr);
          gnu_expr
            = emit_check
              (build_binary_op (EQ_EXPR, integer_type_node,
                                gnu_expr,
                                attribute == Attr_Pred
                                ? TYPE_MIN_VALUE (gnu_result_type)
                                : TYPE_MAX_VALUE (gnu_result_type)),
               gnu_expr, CE_Range_Check_Failed);
        }

      gnu_result
        = build_binary_op (attribute == Attr_Pred
                           ? MINUS_EXPR : PLUS_EXPR,
                           gnu_result_type, gnu_expr,
                           convert (gnu_result_type, integer_one_node));
      break;

    case Attr_Address:
    case Attr_Unrestricted_Access:
      /* Conversions don't change something's address but can cause us to miss
         the COMPONENT_REF case below, so strip them off.  */
      gnu_prefix = remove_conversions (gnu_prefix,
                                       !Must_Be_Byte_Aligned (gnat_node));

      /* If we are taking 'Address of an unconstrained object, this is the
         pointer to the underlying array.  */
      if (attribute == Attr_Address)
        gnu_prefix = maybe_unconstrained_array (gnu_prefix);

      /* If we are building a static dispatch table, we have to honor
         TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
         with the C++ ABI.  We do it in the non-static case as well,
         see gnat_to_gnu_entity, case E_Access_Subprogram_Type.  */
      else if (TARGET_VTABLE_USES_DESCRIPTORS
               && Is_Dispatch_Table_Entity (Etype (gnat_node)))
        {
          tree gnu_field, gnu_list = NULL_TREE, t;
          /* Descriptors can only be built here for top-level functions.  */
          bool build_descriptor = (global_bindings_p () != 0);
          int i;

          gnu_result_type = get_unpadded_type (Etype (gnat_node));

          /* If we're not going to build the descriptor, we have to retrieve
             the one which will be built by the linker (or by the compiler
             later if a static chain is requested).  */
          if (!build_descriptor)
            {
              gnu_result = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_prefix);
              gnu_result = fold_convert (build_pointer_type (gnu_result_type),
                                         gnu_result);
              gnu_result = build1 (INDIRECT_REF, gnu_result_type, gnu_result);
            }

          for (gnu_field = TYPE_FIELDS (gnu_result_type), i = 0;
               i < TARGET_VTABLE_USES_DESCRIPTORS;
               gnu_field = TREE_CHAIN (gnu_field), i++)
            {
              if (build_descriptor)
                {
                  t = build2 (FDESC_EXPR, TREE_TYPE (gnu_field), gnu_prefix,
                              build_int_cst (NULL_TREE, i));
                  TREE_CONSTANT (t) = 1;
                }
              else
                t = build3 (COMPONENT_REF, ptr_void_ftype, gnu_result,
                            gnu_field, NULL_TREE);

              gnu_list = tree_cons (gnu_field, t, gnu_list);
            }

          gnu_result = gnat_build_constructor (gnu_result_type, gnu_list);
          break;
        }

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

    case Attr_Access:
    case Attr_Unchecked_Access:
    case Attr_Code_Address:
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result
        = build_unary_op (((attribute == Attr_Address
                            || attribute == Attr_Unrestricted_Access)
                           && !Must_Be_Byte_Aligned (gnat_node))
                          ? ATTR_ADDR_EXPR : ADDR_EXPR,
                          gnu_result_type, gnu_prefix);

      /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
         don't try to build a trampoline.  */
      if (attribute == Attr_Code_Address)
        {
          for (gnu_expr = gnu_result;
               CONVERT_EXPR_P (gnu_expr);
               gnu_expr = TREE_OPERAND (gnu_expr, 0))
            TREE_CONSTANT (gnu_expr) = 1;

          if (TREE_CODE (gnu_expr) == ADDR_EXPR)
            TREE_NO_TRAMPOLINE (gnu_expr) = TREE_CONSTANT (gnu_expr) = 1;
        }

      /* For other address attributes applied to a nested function,
         find an inner ADDR_EXPR and annotate it so that we can issue
         a useful warning with -Wtrampolines.  */
      else if (TREE_CODE (TREE_TYPE (gnu_prefix)) == FUNCTION_TYPE)
        {
          for (gnu_expr = gnu_result;
               CONVERT_EXPR_P (gnu_expr);
               gnu_expr = TREE_OPERAND (gnu_expr, 0))
            ;

          if (TREE_CODE (gnu_expr) == ADDR_EXPR
              && decl_function_context (TREE_OPERAND (gnu_expr, 0)))
            {
              set_expr_location_from_node (gnu_expr, gnat_node);

              /* Check that we're not violating the No_Implicit_Dynamic_Code
                 restriction.  Be conservative if we don't know anything
                 about the trampoline strategy for the target.  */
              Check_Implicit_Dynamic_Code_Allowed (gnat_node);
            }
        }
      break;

    case Attr_Pool_Address:
      {
        tree gnu_obj_type;
        tree gnu_ptr = gnu_prefix;

        gnu_result_type = get_unpadded_type (Etype (gnat_node));

        /* If this is an unconstrained array, we know the object must have been
           allocated with the template in front of the object.  So compute the
           template address.*/
        if (TYPE_FAT_POINTER_P (TREE_TYPE (gnu_ptr)))
          gnu_ptr
            = convert (build_pointer_type
                       (TYPE_OBJECT_RECORD_TYPE
                        (TYPE_UNCONSTRAINED_ARRAY (TREE_TYPE (gnu_ptr)))),
                       gnu_ptr);

        gnu_obj_type = TREE_TYPE (TREE_TYPE (gnu_ptr));
        if (TREE_CODE (gnu_obj_type) == RECORD_TYPE
            && TYPE_CONTAINS_TEMPLATE_P (gnu_obj_type))
          {
            tree gnu_char_ptr_type = build_pointer_type (char_type_node);
            tree gnu_pos = byte_position (TYPE_FIELDS (gnu_obj_type));
            tree gnu_byte_offset
              = convert (sizetype,
                         size_diffop (size_zero_node, gnu_pos));
            gnu_byte_offset = fold_build1 (NEGATE_EXPR, sizetype, gnu_byte_offset);

            gnu_ptr = convert (gnu_char_ptr_type, gnu_ptr);
            gnu_ptr = build_binary_op (POINTER_PLUS_EXPR, gnu_char_ptr_type,
                                       gnu_ptr, gnu_byte_offset);
          }

        gnu_result = convert (gnu_result_type, gnu_ptr);
      }
      break;

    case Attr_Size:
    case Attr_Object_Size:
    case Attr_Value_Size:
    case Attr_Max_Size_In_Storage_Elements:
      gnu_expr = gnu_prefix;

      /* Remove NOPS from gnu_expr and conversions from gnu_prefix.
         We only use GNU_EXPR to see if a COMPONENT_REF was involved. */
      while (TREE_CODE (gnu_expr) == NOP_EXPR)
        gnu_expr = TREE_OPERAND (gnu_expr, 0);

      gnu_prefix = remove_conversions (gnu_prefix, true);
      prefix_unused = true;
      gnu_type = TREE_TYPE (gnu_prefix);

      /* Replace an unconstrained array type with the type of the underlying
         array.  We can't do this with a call to maybe_unconstrained_array
         since we may have a TYPE_DECL.  For 'Max_Size_In_Storage_Elements,
         use the record type that will be used to allocate the object and its
         template.  */
      if (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE)
        {
          gnu_type = TYPE_OBJECT_RECORD_TYPE (gnu_type);
          if (attribute != Attr_Max_Size_In_Storage_Elements)
            gnu_type = TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_type)));
        }

      /* If we're looking for the size of a field, return the field size.
         Otherwise, if the prefix is an object, or if 'Object_Size or
         'Max_Size_In_Storage_Elements has been specified, the result is the
         GCC size of the type.  Otherwise, the result is the RM_Size of the
         type.  */
      if (TREE_CODE (gnu_prefix) == COMPONENT_REF)
        gnu_result = DECL_SIZE (TREE_OPERAND (gnu_prefix, 1));
      else if (TREE_CODE (gnu_prefix) != TYPE_DECL
               || attribute == Attr_Object_Size
               || attribute == Attr_Max_Size_In_Storage_Elements)
        {
          /* If this is a padded type, the GCC size isn't relevant to the
             programmer.  Normally, what we want is the RM_Size, which was set
             from the specified size, but if it was not set, we want the size
             of the relevant field.  Using the MAX of those two produces the
             right result in all case.  Don't use the size of the field if it's
             a self-referential type, since that's never what's wanted.  */
          if (TREE_CODE (gnu_type) == RECORD_TYPE
              && TYPE_IS_PADDING_P (gnu_type)
              && TREE_CODE (gnu_expr) == COMPONENT_REF)
            {
              gnu_result = rm_size (gnu_type);
              if (!(CONTAINS_PLACEHOLDER_P
                    (DECL_SIZE (TREE_OPERAND (gnu_expr, 1)))))
                gnu_result
                  = size_binop (MAX_EXPR, gnu_result,
                                DECL_SIZE (TREE_OPERAND (gnu_expr, 1)));
            }
          else if (Nkind (Prefix (gnat_node)) == N_Explicit_Dereference)
            {
              Node_Id gnat_deref = Prefix (gnat_node);
              Node_Id gnat_actual_subtype = Actual_Designated_Subtype (gnat_deref);
              tree gnu_ptr_type = TREE_TYPE (gnat_to_gnu (Prefix (gnat_deref)));
              if (TYPE_FAT_OR_THIN_POINTER_P (gnu_ptr_type)
                && Present (gnat_actual_subtype))
                {
                  tree gnu_actual_obj_type = gnat_to_gnu_type (gnat_actual_subtype);
                  gnu_type = build_unc_object_type_from_ptr (gnu_ptr_type,
                               gnu_actual_obj_type, get_identifier ("SIZE"));
                }

              gnu_result = TYPE_SIZE (gnu_type);
            }
          else
            gnu_result = TYPE_SIZE (gnu_type);
        }
      else
        gnu_result = rm_size (gnu_type);

      gcc_assert (gnu_result);

      /* Deal with a self-referential size by returning the maximum size for a
         type and by qualifying the size with the object for 'Size of an
         object.  */
      if (CONTAINS_PLACEHOLDER_P (gnu_result))
        {
          if (TREE_CODE (gnu_prefix) != TYPE_DECL)
            gnu_result = substitute_placeholder_in_expr (gnu_result, gnu_expr);
          else
            gnu_result = max_size (gnu_result, true);
        }

      /* If the type contains a template, subtract its size.  */
      if (TREE_CODE (gnu_type) == RECORD_TYPE
          && TYPE_CONTAINS_TEMPLATE_P (gnu_type))
        gnu_result = size_binop (MINUS_EXPR, gnu_result,
                                 DECL_SIZE (TYPE_FIELDS (gnu_type)));

      gnu_result_type = get_unpadded_type (Etype (gnat_node));

      /* Always perform division using unsigned arithmetic as the size cannot
         be negative, but may be an overflowed positive value. This provides
         correct results for sizes up to 512 MB.

         ??? Size should be calculated in storage elements directly.  */

      if (attribute == Attr_Max_Size_In_Storage_Elements)
        gnu_result = convert (sizetype,
                              fold_build2 (CEIL_DIV_EXPR, bitsizetype,
                                           gnu_result, bitsize_unit_node));
      break;

    case Attr_Alignment:
      if (TREE_CODE (gnu_prefix) == COMPONENT_REF
          && (TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_prefix, 0)))
              == RECORD_TYPE)
          && (TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_prefix, 0)))))
        gnu_prefix = TREE_OPERAND (gnu_prefix, 0);

      gnu_type = TREE_TYPE (gnu_prefix);
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      prefix_unused = true;

      gnu_result = size_int ((TREE_CODE (gnu_prefix) == COMPONENT_REF
                              ? DECL_ALIGN (TREE_OPERAND (gnu_prefix, 1))
                              : TYPE_ALIGN (gnu_type)) / BITS_PER_UNIT);
      break;

    case Attr_First:
    case Attr_Last:
    case Attr_Range_Length:
      prefix_unused = true;

      if (INTEGRAL_TYPE_P (gnu_type) || TREE_CODE (gnu_type) == REAL_TYPE)
        {
          gnu_result_type = get_unpadded_type (Etype (gnat_node));

          if (attribute == Attr_First)
            gnu_result = TYPE_MIN_VALUE (gnu_type);
          else if (attribute == Attr_Last)
            gnu_result = TYPE_MAX_VALUE (gnu_type);
          else
            gnu_result
              = build_binary_op
                (MAX_EXPR, get_base_type (gnu_result_type),
                 build_binary_op
                 (PLUS_EXPR, get_base_type (gnu_result_type),
                  build_binary_op (MINUS_EXPR,
                                   get_base_type (gnu_result_type),
                                   convert (gnu_result_type,
                                            TYPE_MAX_VALUE (gnu_type)),
                                   convert (gnu_result_type,
                                            TYPE_MIN_VALUE (gnu_type))),
                  convert (gnu_result_type, integer_one_node)),
                 convert (gnu_result_type, integer_zero_node));

          break;
        }

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

    case Attr_Length:
      {
        int Dimension = (Present (Expressions (gnat_node))
                         ? UI_To_Int (Intval (First (Expressions (gnat_node))))
                         : 1), i;
        struct parm_attr *pa = NULL;
        Entity_Id gnat_param = Empty;

        /* Make sure any implicit dereference gets done.  */
        gnu_prefix = maybe_implicit_deref (gnu_prefix);
        gnu_prefix = maybe_unconstrained_array (gnu_prefix);
        /* We treat unconstrained array In parameters specially.  */
        if (Nkind (Prefix (gnat_node)) == N_Identifier
            && !Is_Constrained (Etype (Prefix (gnat_node)))
            && Ekind (Entity (Prefix (gnat_node))) == E_In_Parameter)
          gnat_param = Entity (Prefix (gnat_node));
        gnu_type = TREE_TYPE (gnu_prefix);
        prefix_unused = true;
        gnu_result_type = get_unpadded_type (Etype (gnat_node));

        if (TYPE_CONVENTION_FORTRAN_P (gnu_type))
          {
            int ndim;
            tree gnu_type_temp;

            for (ndim = 1, gnu_type_temp = gnu_type;
                 TREE_CODE (TREE_TYPE (gnu_type_temp)) == ARRAY_TYPE
                 && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_type_temp));
                 ndim++, gnu_type_temp = TREE_TYPE (gnu_type_temp))
              ;

            Dimension = ndim + 1 - Dimension;
          }

        for (i = 1; i < Dimension; i++)
          gnu_type = TREE_TYPE (gnu_type);

        gcc_assert (TREE_CODE (gnu_type) == ARRAY_TYPE);

        /* When not optimizing, look up the slot associated with the parameter
           and the dimension in the cache and create a new one on failure.  */
        if (!optimize && Present (gnat_param))
          {
            for (i = 0; VEC_iterate (parm_attr, f_parm_attr_cache, i, pa); i++)
              if (pa->id == gnat_param && pa->dim == Dimension)
                break;

            if (!pa)
              {
                pa = GGC_CNEW (struct parm_attr);
                pa->id = gnat_param;
                pa->dim = Dimension;
                VEC_safe_push (parm_attr, gc, f_parm_attr_cache, pa);
              }
          }

        /* Return the cached expression or build a new one.  */
        if (attribute == Attr_First)
          {
            if (pa && pa->first)
              {
                gnu_result = pa->first;
                break;
              }

            gnu_result
              = TYPE_MIN_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type)));
          }

        else if (attribute == Attr_Last)
          {
            if (pa && pa->last)
              {
                gnu_result = pa->last;
                break;
              }

            gnu_result
              = TYPE_MAX_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type)));
          }

        else /* attribute == Attr_Range_Length || attribute == Attr_Length  */
          {
            if (pa && pa->length)
              {
                gnu_result = pa->length;
                break;
              }
            else
              {
                /* We used to compute the length as max (hb - lb + 1, 0),
                   which could overflow for some cases of empty arrays, e.g.
                   when lb == index_type'first.  We now compute the length as
                   (hb < lb) ? 0 : hb - lb + 1, which would only overflow in
                   much rarer cases, for extremely large arrays we expect
                   never to encounter in practice.  In addition, the former
                   computation required the use of potentially constraining
                   signed arithmetic while the latter doesn't.  */
                
                tree gnu_compute_type = get_base_type (gnu_result_type);

                tree index_type
                  = TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type));
                tree lb
                  = convert (gnu_compute_type, TYPE_MIN_VALUE (index_type));
                tree hb
                  = convert (gnu_compute_type, TYPE_MAX_VALUE (index_type));
                
                gnu_result
                  = build3
                    (COND_EXPR, gnu_compute_type,
                     build_binary_op (LT_EXPR, gnu_compute_type, hb, lb),
                     convert (gnu_compute_type, integer_zero_node),
                     build_binary_op
                     (PLUS_EXPR, gnu_compute_type,
                      build_binary_op (MINUS_EXPR, gnu_compute_type, hb, lb),
                      convert (gnu_compute_type, integer_one_node)));
              }
          }

        /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
           handling.  Note that these attributes could not have been used on
           an unconstrained array type.  */
        gnu_result = SUBSTITUTE_PLACEHOLDER_IN_EXPR (gnu_result,
                                                     gnu_prefix);

        /* Cache the expression we have just computed.  Since we want to do it
           at runtime, we force the use of a SAVE_EXPR and let the gimplifier
           create the temporary.  */
        if (pa)
          {
            gnu_result
              = build1 (SAVE_EXPR, TREE_TYPE (gnu_result), gnu_result);
            TREE_SIDE_EFFECTS (gnu_result) = 1;
            if (attribute == Attr_First)
              pa->first = gnu_result;
            else if (attribute == Attr_Last)
              pa->last = gnu_result;
            else
              pa->length = gnu_result;
          }
        break;
      }

    case Attr_Bit_Position:
    case Attr_Position:
    case Attr_First_Bit:
    case Attr_Last_Bit:
    case Attr_Bit:
      {
        HOST_WIDE_INT bitsize;
        HOST_WIDE_INT bitpos;
        tree gnu_offset;
        tree gnu_field_bitpos;
        tree gnu_field_offset;
        tree gnu_inner;
        enum machine_mode mode;
        int unsignedp, volatilep;

        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        gnu_prefix = remove_conversions (gnu_prefix, true);
        prefix_unused = true;

        /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
           the result is 0.  Don't allow 'Bit on a bare component, though. */
        if (attribute == Attr_Bit
            && TREE_CODE (gnu_prefix) != COMPONENT_REF
            && TREE_CODE (gnu_prefix) != FIELD_DECL)
          {
            gnu_result = integer_zero_node;
            break;
          }

        else
          gcc_assert (TREE_CODE (gnu_prefix) == COMPONENT_REF
                      || (attribute == Attr_Bit_Position
                          && TREE_CODE (gnu_prefix) == FIELD_DECL));

        get_inner_reference (gnu_prefix, &bitsize, &bitpos, &gnu_offset,
                             &mode, &unsignedp, &volatilep, false);

        if (TREE_CODE (gnu_prefix) == COMPONENT_REF)
          {
            gnu_field_bitpos = bit_position (TREE_OPERAND (gnu_prefix, 1));
            gnu_field_offset = byte_position (TREE_OPERAND (gnu_prefix, 1));

            for (gnu_inner = TREE_OPERAND (gnu_prefix, 0);
                 TREE_CODE (gnu_inner) == COMPONENT_REF
                 && DECL_INTERNAL_P (TREE_OPERAND (gnu_inner, 1));
                 gnu_inner = TREE_OPERAND (gnu_inner, 0))
              {
                gnu_field_bitpos
                  = size_binop (PLUS_EXPR, gnu_field_bitpos,
                                bit_position (TREE_OPERAND (gnu_inner, 1)));
                gnu_field_offset
                  = size_binop (PLUS_EXPR, gnu_field_offset,
                                byte_position (TREE_OPERAND (gnu_inner, 1)));
              }
          }
        else if (TREE_CODE (gnu_prefix) == FIELD_DECL)
          {
            gnu_field_bitpos = bit_position (gnu_prefix);
            gnu_field_offset = byte_position (gnu_prefix);
          }
        else
          {
            gnu_field_bitpos = bitsize_zero_node;
            gnu_field_offset = size_zero_node;
          }

        switch (attribute)
          {
          case Attr_Position:
            gnu_result = gnu_field_offset;
            break;

          case Attr_First_Bit:
          case Attr_Bit:
            gnu_result = size_int (bitpos % BITS_PER_UNIT);
            break;

          case Attr_Last_Bit:
            gnu_result = bitsize_int (bitpos % BITS_PER_UNIT);
            gnu_result = size_binop (PLUS_EXPR, gnu_result,
                                     TYPE_SIZE (TREE_TYPE (gnu_prefix)));
            gnu_result = size_binop (MINUS_EXPR, gnu_result,
                                     bitsize_one_node);
            break;

          case Attr_Bit_Position:
            gnu_result = gnu_field_bitpos;
            break;
                }

        /* If this has a PLACEHOLDER_EXPR, qualify it by the object
           we are handling. */
        gnu_result = SUBSTITUTE_PLACEHOLDER_IN_EXPR (gnu_result, gnu_prefix);
        break;
      }

    case Attr_Min:
    case Attr_Max:
      {
        tree gnu_lhs = gnat_to_gnu (First (Expressions (gnat_node)));
        tree gnu_rhs = gnat_to_gnu (Next (First (Expressions (gnat_node))));

        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        gnu_result = build_binary_op (attribute == Attr_Min
                                      ? MIN_EXPR : MAX_EXPR,
                                      gnu_result_type, gnu_lhs, gnu_rhs);
      }
      break;

    case Attr_Passed_By_Reference:
      gnu_result = size_int (default_pass_by_ref (gnu_type)
                             || must_pass_by_ref (gnu_type));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      break;

    case Attr_Component_Size:
      if (TREE_CODE (gnu_prefix) == COMPONENT_REF
          && (TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_prefix, 0)))
              == RECORD_TYPE)
          && (TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_prefix, 0)))))
        gnu_prefix = TREE_OPERAND (gnu_prefix, 0);

      gnu_prefix = maybe_implicit_deref (gnu_prefix);
      gnu_type = TREE_TYPE (gnu_prefix);

      if (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE)
        gnu_type = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_type))));

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

      gcc_assert (TREE_CODE (gnu_type) == ARRAY_TYPE);

      /* Note this size cannot be self-referential.  */
      gnu_result = TYPE_SIZE (TREE_TYPE (gnu_type));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      prefix_unused = true;
      break;

    case Attr_Null_Parameter:
      /* This is just a zero cast to the pointer type for
         our prefix and dereferenced.  */
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result
        = build_unary_op (INDIRECT_REF, NULL_TREE,
                          convert (build_pointer_type (gnu_result_type),
                                   integer_zero_node));
      TREE_PRIVATE (gnu_result) = 1;
      break;

    case Attr_Mechanism_Code:
      {
        int code;
        Entity_Id gnat_obj = Entity (Prefix (gnat_node));

        prefix_unused = true;
        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        if (Present (Expressions (gnat_node)))
          {
            int i = UI_To_Int (Intval (First (Expressions (gnat_node))));

            for (gnat_obj = First_Formal (gnat_obj); i > 1;
                 i--, gnat_obj = Next_Formal (gnat_obj))
              ;
          }

        code = Mechanism (gnat_obj);
        if (code == Default)
          code = ((present_gnu_tree (gnat_obj)
                   && (DECL_BY_REF_P (get_gnu_tree (gnat_obj))
                       || ((TREE_CODE (get_gnu_tree (gnat_obj))
                            == PARM_DECL)
                           && (DECL_BY_COMPONENT_PTR_P
                               (get_gnu_tree (gnat_obj))))))
                  ? By_Reference : By_Copy);
        gnu_result = convert (gnu_result_type, size_int (- code));
      }
      break;

    default:
      /* Say we have an unimplemented attribute.  Then set the value to be
         returned to be a zero and hope that's something we can convert to the
         type of this attribute.  */
      post_error ("unimplemented attribute", gnat_node);
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result = integer_zero_node;
      break;
    }

  /* If this is an attribute where the prefix was unused, force a use of it if
     it has a side-effect.  But don't do it if the prefix is just an entity
     name.  However, if an access check is needed, we must do it.  See second
     example in AARM 11.6(5.e). */
  if (prefix_unused && TREE_SIDE_EFFECTS (gnu_prefix)
      && !Is_Entity_Name (Prefix (gnat_node)))
    gnu_result = fold_build2 (COMPOUND_EXPR, TREE_TYPE (gnu_result),
                              gnu_prefix, gnu_result);

  *gnu_result_type_p = gnu_result_type;
  return gnu_result;
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
   to a GCC tree, which is returned.  */

static tree
Case_Statement_to_gnu (Node_Id gnat_node)
{
  tree gnu_result;
  tree gnu_expr;
  Node_Id gnat_when;

  gnu_expr = gnat_to_gnu (Expression (gnat_node));
  gnu_expr = convert (get_base_type (TREE_TYPE (gnu_expr)), gnu_expr);

  /*  The range of values in a case statement is determined by the rules in
      RM 5.4(7-9). In almost all cases, this range is represented by the Etype
      of the expression. One exception arises in the case of a simple name that
      is parenthesized. This still has the Etype of the name, but since it is
      not a name, para 7 does not apply, and we need to go to the base type.
      This is the only case where parenthesization affects the dynamic
      semantics (i.e. the range of possible values at runtime that is covered
      by the others alternative.

      Another exception is if the subtype of the expression is non-static.  In
      that case, we also have to use the base type.  */
  if (Paren_Count (Expression (gnat_node)) != 0
      || !Is_OK_Static_Subtype (Underlying_Type
                                (Etype (Expression (gnat_node)))))
    gnu_expr = convert (get_base_type (TREE_TYPE (gnu_expr)), gnu_expr);

  /* We build a SWITCH_EXPR that contains the code with interspersed
     CASE_LABEL_EXPRs for each label.  */

  push_stack (&gnu_switch_label_stack, NULL_TREE, create_artificial_label ());
  start_stmt_group ();
  for (gnat_when = First_Non_Pragma (Alternatives (gnat_node));
       Present (gnat_when);
       gnat_when = Next_Non_Pragma (gnat_when))
    {
      Node_Id gnat_choice;
      int choices_added = 0;

      /* First compile all the different case choices for the current WHEN
         alternative.  */
      for (gnat_choice = First (Discrete_Choices (gnat_when));
           Present (gnat_choice); gnat_choice = Next (gnat_choice))
        {
          tree gnu_low = NULL_TREE, gnu_high = NULL_TREE;

          switch (Nkind (gnat_choice))
            {
            case N_Range:
              gnu_low = gnat_to_gnu (Low_Bound (gnat_choice));
              gnu_high = gnat_to_gnu (High_Bound (gnat_choice));
              break;

            case N_Subtype_Indication:
              gnu_low = gnat_to_gnu (Low_Bound (Range_Expression
                                                (Constraint (gnat_choice))));
              gnu_high = gnat_to_gnu (High_Bound (Range_Expression
                                                  (Constraint (gnat_choice))));
              break;

            case N_Identifier:
            case N_Expanded_Name:
              /* This represents either a subtype range or a static value of
                 some kind; Ekind says which.  */
              if (IN (Ekind (Entity (gnat_choice)), Type_Kind))
                {
                  tree gnu_type = get_unpadded_type (Entity (gnat_choice));

                  gnu_low = fold (TYPE_MIN_VALUE (gnu_type));
                  gnu_high = fold (TYPE_MAX_VALUE (gnu_type));
                  break;
                }

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

            case N_Character_Literal:
            case N_Integer_Literal:
              gnu_low = gnat_to_gnu (gnat_choice);
              break;

            case N_Others_Choice:
              break;

            default:
              gcc_unreachable ();
            }

          /* If the case value is a subtype that raises Constraint_Error at
             run-time because of a wrong bound, then gnu_low or gnu_high is
             not transtaleted into an INTEGER_CST.  In such a case, we need
             to ensure that the when statement is not added in the tree,
             otherwise it will crash the gimplifier.  */
          if ((!gnu_low || TREE_CODE (gnu_low) == INTEGER_CST)
              && (!gnu_high || TREE_CODE (gnu_high) == INTEGER_CST))
            {
              add_stmt_with_node (build3 (CASE_LABEL_EXPR, void_type_node,
                                          gnu_low, gnu_high,
                                          create_artificial_label ()),
                                  gnat_choice);
              choices_added++;
            }
        }

      /* Push a binding level here in case variables are declared as we want
         them to be local to this set of statements instead of to the block
         containing the Case statement.  */
      if (choices_added > 0)
        {
          add_stmt (build_stmt_group (Statements (gnat_when), true));
          add_stmt (build1 (GOTO_EXPR, void_type_node,
                            TREE_VALUE (gnu_switch_label_stack)));
        }
    }

  /* Now emit a definition of the label all the cases branched to. */
  add_stmt (build1 (LABEL_EXPR, void_type_node,
                    TREE_VALUE (gnu_switch_label_stack)));
  gnu_result = build3 (SWITCH_EXPR, TREE_TYPE (gnu_expr), gnu_expr,
                       end_stmt_group (), NULL_TREE);
  pop_stack (&gnu_switch_label_stack);

  return gnu_result;
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
   to a GCC tree, which is returned.  */

static tree
Loop_Statement_to_gnu (Node_Id gnat_node)
{
  /* ??? It would be nice to use "build" here, but there's no build5.  */
  tree gnu_loop_stmt = build_nt (LOOP_STMT, NULL_TREE, NULL_TREE,
                                 NULL_TREE, NULL_TREE, NULL_TREE);
  tree gnu_loop_var = NULL_TREE;
  Node_Id gnat_iter_scheme = Iteration_Scheme (gnat_node);
  tree gnu_cond_expr = NULL_TREE;
  tree gnu_result;

  TREE_TYPE (gnu_loop_stmt) = void_type_node;
  TREE_SIDE_EFFECTS (gnu_loop_stmt) = 1;
  LOOP_STMT_LABEL (gnu_loop_stmt) = create_artificial_label ();
  set_expr_location_from_node (gnu_loop_stmt, gnat_node);
  Sloc_to_locus (Sloc (End_Label (gnat_node)),
                 &DECL_SOURCE_LOCATION (LOOP_STMT_LABEL (gnu_loop_stmt)));

  /* Save the end label of this LOOP_STMT in a stack so that the corresponding
     N_Exit_Statement can find it.  */
  push_stack (&gnu_loop_label_stack, NULL_TREE,
              LOOP_STMT_LABEL (gnu_loop_stmt));

  /* Set the condition that under which the loop should continue.
     For "LOOP .... END LOOP;" the condition is always true.  */
  if (No (gnat_iter_scheme))
    ;
  /* The case "WHILE condition LOOP ..... END LOOP;" */
  else if (Present (Condition (gnat_iter_scheme)))
    LOOP_STMT_TOP_COND (gnu_loop_stmt)
      = gnat_to_gnu (Condition (gnat_iter_scheme));
  else
    {
      /* We have an iteration scheme.  */
      Node_Id gnat_loop_spec = Loop_Parameter_Specification (gnat_iter_scheme);
      Entity_Id gnat_loop_var = Defining_Entity (gnat_loop_spec);
      Entity_Id gnat_type = Etype (gnat_loop_var);
      tree gnu_type = get_unpadded_type (gnat_type);
      tree gnu_low = TYPE_MIN_VALUE (gnu_type);
      tree gnu_high = TYPE_MAX_VALUE (gnu_type);
      bool reversep = Reverse_Present (gnat_loop_spec);
      tree gnu_first = reversep ? gnu_high : gnu_low;
      tree gnu_last = reversep ? gnu_low : gnu_high;
      enum tree_code end_code = reversep ? GE_EXPR : LE_EXPR;
      tree gnu_base_type = get_base_type (gnu_type);
      tree gnu_limit = (reversep ? TYPE_MIN_VALUE (gnu_base_type)
                        : TYPE_MAX_VALUE (gnu_base_type));

      /* We know the loop variable will not overflow if GNU_LAST is a constant
         and is not equal to GNU_LIMIT.  If it might overflow, we have to move
         the limit test to the end of the loop.  In that case, we have to test
         for an empty loop outside the loop.  */
      if (TREE_CODE (gnu_last) != INTEGER_CST
          || TREE_CODE (gnu_limit) != INTEGER_CST
          || tree_int_cst_equal (gnu_last, gnu_limit))
        {
          gnu_cond_expr
            = build3 (COND_EXPR, void_type_node,
                      build_binary_op (LE_EXPR, integer_type_node,
                                       gnu_low, gnu_high),
                      NULL_TREE, alloc_stmt_list ());
          set_expr_location_from_node (gnu_cond_expr, gnat_loop_spec);
        }

      /* Open a new nesting level that will surround the loop to declare the
         loop index variable.  */
      start_stmt_group ();
      gnat_pushlevel ();

      /* Declare the loop index and set it to its initial value.  */
      gnu_loop_var = gnat_to_gnu_entity (gnat_loop_var, gnu_first, 1);
      if (DECL_BY_REF_P (gnu_loop_var))
        gnu_loop_var = build_unary_op (INDIRECT_REF, NULL_TREE, gnu_loop_var);

      /* The loop variable might be a padded type, so use `convert' to get a
         reference to the inner variable if so.  */
      gnu_loop_var = convert (get_base_type (gnu_type), gnu_loop_var);

      /* Set either the top or bottom exit condition as appropriate depending
         on whether or not we know an overflow cannot occur. */
      if (gnu_cond_expr)
        LOOP_STMT_BOT_COND (gnu_loop_stmt)
          = build_binary_op (NE_EXPR, integer_type_node,
                             gnu_loop_var, gnu_last);
      else
        LOOP_STMT_TOP_COND (gnu_loop_stmt)
          = build_binary_op (end_code, integer_type_node,
                             gnu_loop_var, gnu_last);

      LOOP_STMT_UPDATE (gnu_loop_stmt)
        = build_binary_op (reversep ? PREDECREMENT_EXPR
                           : PREINCREMENT_EXPR,
                           TREE_TYPE (gnu_loop_var),
                           gnu_loop_var,
                           convert (TREE_TYPE (gnu_loop_var),
                                    integer_one_node));
      set_expr_location_from_node (LOOP_STMT_UPDATE (gnu_loop_stmt),
                          gnat_iter_scheme);
    }

  /* If the loop was named, have the name point to this loop.  In this case,
     the association is not a ..._DECL node, but the end label from this
     LOOP_STMT. */
  if (Present (Identifier (gnat_node)))
    save_gnu_tree (Entity (Identifier (gnat_node)),
                   LOOP_STMT_LABEL (gnu_loop_stmt), true);

  /* Make the loop body into its own block, so any allocated storage will be
     released every iteration.  This is needed for stack allocation.  */
  LOOP_STMT_BODY (gnu_loop_stmt)
    = build_stmt_group (Statements (gnat_node), true);

  /* If we declared a variable, then we are in a statement group for that
     declaration.  Add the LOOP_STMT to it and make that the "loop".  */
  if (gnu_loop_var)
    {
      add_stmt (gnu_loop_stmt);
      gnat_poplevel ();
      gnu_loop_stmt = end_stmt_group ();
    }

  /* If we have an outer COND_EXPR, that's our result and this loop is its
     "true" statement.  Otherwise, the result is the LOOP_STMT. */
  if (gnu_cond_expr)
    {
      COND_EXPR_THEN (gnu_cond_expr) = gnu_loop_stmt;
      gnu_result = gnu_cond_expr;
      recalculate_side_effects (gnu_cond_expr);
    }
  else
    gnu_result = gnu_loop_stmt;

  pop_stack (&gnu_loop_label_stack);

  return gnu_result;
}
\f
/* Emit statements to establish __gnat_handle_vms_condition as a VMS condition
   handler for the current function.  */

/* This is implemented by issuing a call to the appropriate VMS specific
   builtin.  To avoid having VMS specific sections in the global gigi decls
   array, we maintain the decls of interest here.  We can't declare them
   inside the function because we must mark them never to be GC'd, which we
   can only do at the global level.  */

static GTY(()) tree vms_builtin_establish_handler_decl = NULL_TREE;
static GTY(()) tree gnat_vms_condition_handler_decl = NULL_TREE;

static void
establish_gnat_vms_condition_handler (void)
{
  tree establish_stmt;

  /* Elaborate the required decls on the first call.  Check on the decl for
     the gnat condition handler to decide, as this is one we create so we are
     sure that it will be non null on subsequent calls.  The builtin decl is
     looked up so remains null on targets where it is not implemented yet.  */
  if (gnat_vms_condition_handler_decl == NULL_TREE)
    {
      vms_builtin_establish_handler_decl
        = builtin_decl_for
          (get_identifier ("__builtin_establish_vms_condition_handler"));

      gnat_vms_condition_handler_decl
        = create_subprog_decl (get_identifier ("__gnat_handle_vms_condition"),
                               NULL_TREE,
                               build_function_type_list (integer_type_node,
                                                         ptr_void_type_node,
                                                         ptr_void_type_node,
                                                         NULL_TREE),
                               NULL_TREE, 0, 1, 1, 0, Empty);
    }

  /* Do nothing if the establish builtin is not available, which might happen
     on targets where the facility is not implemented.  */
  if (vms_builtin_establish_handler_decl == NULL_TREE)
    return;

  establish_stmt
    = build_call_1_expr (vms_builtin_establish_handler_decl,
                         build_unary_op
                         (ADDR_EXPR, NULL_TREE,
                          gnat_vms_condition_handler_decl));

  add_stmt (establish_stmt);
}
\f
/* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body.  We
   don't return anything.  */

static void
Subprogram_Body_to_gnu (Node_Id gnat_node)
{
  /* Defining identifier of a parameter to the subprogram.  */
  Entity_Id gnat_param;
  /* The defining identifier for the subprogram body. Note that if a
     specification has appeared before for this body, then the identifier
     occurring in that specification will also be a defining identifier and all
     the calls to this subprogram will point to that specification.  */
  Entity_Id gnat_subprog_id
    = (Present (Corresponding_Spec (gnat_node))
       ? Corresponding_Spec (gnat_node) : Defining_Entity (gnat_node));
  /* The FUNCTION_DECL node corresponding to the subprogram spec.   */
  tree gnu_subprog_decl;
  /* The FUNCTION_TYPE node corresponding to the subprogram spec.  */
  tree gnu_subprog_type;
  tree gnu_cico_list;
  tree gnu_result;
  VEC(parm_attr,gc) *cache;

  /* If this is a generic object or if it has been eliminated,
     ignore it.  */
  if (Ekind (gnat_subprog_id) == E_Generic_Procedure
      || Ekind (gnat_subprog_id) == E_Generic_Function
      || Is_Eliminated (gnat_subprog_id))
    return;

  /* If this subprogram acts as its own spec, define it.  Otherwise, just get
     the already-elaborated tree node.  However, if this subprogram had its
     elaboration deferred, we will already have made a tree node for it.  So
     treat it as not being defined in that case.  Such a subprogram cannot
     have an address clause or a freeze node, so this test is safe, though it
     does disable some otherwise-useful error checking.  */
  gnu_subprog_decl
    = gnat_to_gnu_entity (gnat_subprog_id, NULL_TREE,
                          Acts_As_Spec (gnat_node)
                          && !present_gnu_tree (gnat_subprog_id));

  gnu_subprog_type = TREE_TYPE (gnu_subprog_decl);

  /* Propagate the debug mode.  */
  if (!Needs_Debug_Info (gnat_subprog_id))
    DECL_IGNORED_P (gnu_subprog_decl) = 1;

  /* Set the line number in the decl to correspond to that of the body so that
     the line number notes are written correctly.  */
  Sloc_to_locus (Sloc (gnat_node), &DECL_SOURCE_LOCATION (gnu_subprog_decl));

  /* Initialize the information structure for the function.  */
  allocate_struct_function (gnu_subprog_decl, false);
  DECL_STRUCT_FUNCTION (gnu_subprog_decl)->language
    = GGC_CNEW (struct language_function);

  begin_subprog_body (gnu_subprog_decl);
  gnu_cico_list = TYPE_CI_CO_LIST (gnu_subprog_type);

  /* If there are Out parameters, we need to ensure that the return statement
     properly copies them out.  We do this by making a new block and converting
     any inner return into a goto to a label at the end of the block.  */
  push_stack (&gnu_return_label_stack, NULL_TREE,
              gnu_cico_list ? create_artificial_label () : NULL_TREE);

  /* Get a tree corresponding to the code for the subprogram.  */
  start_stmt_group ();
  gnat_pushlevel ();

  /* See if there are any parameters for which we don't yet have GCC entities.
     These must be for Out parameters for which we will be making VAR_DECL
     nodes here.  Fill them in to TYPE_CI_CO_LIST, which must contain the empty
     entry as well.  We can match up the entries because TYPE_CI_CO_LIST is in
     the order of the parameters.  */
  for (gnat_param = First_Formal_With_Extras (gnat_subprog_id);
       Present (gnat_param);
       gnat_param = Next_Formal_With_Extras (gnat_param))
    if (!present_gnu_tree (gnat_param))
      {
        /* Skip any entries that have been already filled in; they must
           correspond to In Out parameters.  */
        for (; gnu_cico_list && TREE_VALUE (gnu_cico_list);
             gnu_cico_list = TREE_CHAIN (gnu_cico_list))
          ;

        /* Do any needed references for padded types.  */
        TREE_VALUE (gnu_cico_list)
          = convert (TREE_TYPE (TREE_PURPOSE (gnu_cico_list)),
                     gnat_to_gnu_entity (gnat_param, NULL_TREE, 1));
      }

  /* On VMS, establish our condition handler to possibly turn a condition into
     the corresponding exception if the subprogram has a foreign convention or
     is exported.

     To ensure proper execution of local finalizations on condition instances,
     we must turn a condition into the corresponding exception even if there
     is no applicable Ada handler, and need at least one condition handler per
     possible call chain involving GNAT code.  OTOH, establishing the handler
     has a cost so we want to minimize the number of subprograms into which
     this happens.  The foreign or exported condition is expected to satisfy
     all the constraints.  */
  if (TARGET_ABI_OPEN_VMS
      && (Has_Foreign_Convention (gnat_node) || Is_Exported (gnat_node)))
    establish_gnat_vms_condition_handler ();

  process_decls (Declarations (gnat_node), Empty, Empty, true, true);

  /* Generate the code of the subprogram itself.  A return statement will be
     present and any Out parameters will be handled there.  */
  add_stmt (gnat_to_gnu (Handled_Statement_Sequence (gnat_node)));
  gnat_poplevel ();
  gnu_result = end_stmt_group ();

  /* If we populated the parameter attributes cache, we need to make sure
     that the cached expressions are evaluated on all possible paths.  */
  cache = DECL_STRUCT_FUNCTION (gnu_subprog_decl)->language->parm_attr_cache;
  if (cache)
    {
      struct parm_attr *pa;
      int i;

      start_stmt_group ();

      for (i = 0; VEC_iterate (parm_attr, cache, i, pa); i++)
        {
          if (pa->first)
            add_stmt (pa->first);
          if (pa->last)
            add_stmt (pa->last);
          if (pa->length)
            add_stmt (pa->length);
        }

      add_stmt (gnu_result);
      gnu_result = end_stmt_group ();
    }

  /* If we made a special return label, we need to make a block that contains
     the definition of that label and the copying to the return value.  That
     block first contains the function, then the label and copy statement.  */
  if (TREE_VALUE (gnu_return_label_stack))
    {
      tree gnu_retval;

      start_stmt_group ();
      gnat_pushlevel ();
      add_stmt (gnu_result);
      add_stmt (build1 (LABEL_EXPR, void_type_node,
                        TREE_VALUE (gnu_return_label_stack)));

      gnu_cico_list = TYPE_CI_CO_LIST (gnu_subprog_type);
      if (list_length (gnu_cico_list) == 1)
        gnu_retval = TREE_VALUE (gnu_cico_list);
      else
        gnu_retval = gnat_build_constructor (TREE_TYPE (gnu_subprog_type),
                                             gnu_cico_list);

      if (DECL_P (gnu_retval) && DECL_BY_REF_P (gnu_retval))
        gnu_retval = build_unary_op (INDIRECT_REF, NULL_TREE, gnu_retval);

      add_stmt_with_node
        (build_return_expr (DECL_RESULT (gnu_subprog_decl), gnu_retval),
         gnat_node);
      gnat_poplevel ();
      gnu_result = end_stmt_group ();
    }

  pop_stack (&gnu_return_label_stack);

  /* Set the end location.  */
  Sloc_to_locus
    ((Present (End_Label (Handled_Statement_Sequence (gnat_node)))
      ? Sloc (End_Label (Handled_Statement_Sequence (gnat_node)))
      : Sloc (gnat_node)),
     &DECL_STRUCT_FUNCTION (gnu_subprog_decl)->function_end_locus);

  end_subprog_body (gnu_result);

  /* Disconnect the trees for parameters that we made variables for from the
     GNAT entities since these are unusable after we end the function.  */
  for (gnat_param = First_Formal_With_Extras (gnat_subprog_id);
       Present (gnat_param);
       gnat_param = Next_Formal_With_Extras (gnat_param))
    if (TREE_CODE (get_gnu_tree (gnat_param)) == VAR_DECL)
      save_gnu_tree (gnat_param, NULL_TREE, false);

  if (DECL_FUNCTION_STUB (gnu_subprog_decl))
    build_function_stub (gnu_subprog_decl, gnat_subprog_id);

  mark_out_of_scope (Defining_Unit_Name (Specification (gnat_node)));
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
   or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
   GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
   If GNU_TARGET is non-null, this must be a function call and the result
   of the call is to be placed into that object.  */

static tree
call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target)
{
  tree gnu_result;
  /* The GCC node corresponding to the GNAT subprogram name.  This can either
     be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
     or an indirect reference expression (an INDIRECT_REF node) pointing to a
     subprogram.  */
  tree gnu_subprog_node = gnat_to_gnu (Name (gnat_node));
  /* The FUNCTION_TYPE node giving the GCC type of the subprogram.  */
  tree gnu_subprog_type = TREE_TYPE (gnu_subprog_node);
  tree gnu_subprog_addr = build_unary_op (ADDR_EXPR, NULL_TREE,
                                          gnu_subprog_node);
  Entity_Id gnat_formal;
  Node_Id gnat_actual;
  tree gnu_actual_list = NULL_TREE;
  tree gnu_name_list = NULL_TREE;
  tree gnu_before_list = NULL_TREE;
  tree gnu_after_list = NULL_TREE;
  tree gnu_subprog_call;

  switch (Nkind (Name (gnat_node)))
    {
    case N_Identifier:
    case N_Operator_Symbol:
    case N_Expanded_Name:
    case N_Attribute_Reference:
      if (Is_Eliminated (Entity (Name (gnat_node))))
        Eliminate_Error_Msg (gnat_node, Entity (Name (gnat_node)));
    }

  gcc_assert (TREE_CODE (gnu_subprog_type) == FUNCTION_TYPE);

  /* If we are calling a stubbed function, make this into a raise of
     Program_Error.  Elaborate all our args first.  */
  if (TREE_CODE (gnu_subprog_node) == FUNCTION_DECL
      && DECL_STUBBED_P (gnu_subprog_node))
    {
      for (gnat_actual = First_Actual (gnat_node);
           Present (gnat_actual);
           gnat_actual = Next_Actual (gnat_actual))
        add_stmt (gnat_to_gnu (gnat_actual));

      {
        tree call_expr
          = build_call_raise (PE_Stubbed_Subprogram_Called, gnat_node,
                              N_Raise_Program_Error);

        if (Nkind (gnat_node) == N_Function_Call && !gnu_target)
          {
            *gnu_result_type_p = TREE_TYPE (gnu_subprog_type);
            return build1 (NULL_EXPR, *gnu_result_type_p, call_expr);
          }
        else
          return call_expr;
      }
    }

  /* If we are calling by supplying a pointer to a target, set up that
     pointer as the first argument.  Use GNU_TARGET if one was passed;
     otherwise, make a target by building a variable of the maximum size
     of the type.  */
  if (TYPE_RETURNS_BY_TARGET_PTR_P (gnu_subprog_type))
    {
      tree gnu_real_ret_type
        = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (gnu_subprog_type)));

      if (!gnu_target)
        {
          tree gnu_obj_type
            = maybe_pad_type (gnu_real_ret_type,
                              max_size (TYPE_SIZE (gnu_real_ret_type), true),
                              0, Etype (Name (gnat_node)), "PAD", false,
                              false, false);

          /* ??? We may be about to create a static temporary if we happen to
             be at the global binding level.  That's a regression from what
             the 3.x back-end would generate in the same situation, but we
             don't have a mechanism in Gigi for creating automatic variables
             in the elaboration routines.  */
          gnu_target
            = create_var_decl (create_tmp_var_name ("LR"), NULL, gnu_obj_type,
                               NULL, false, false, false, false, NULL,
                               gnat_node);
        }

      gnu_actual_list
        = tree_cons (NULL_TREE,
                     build_unary_op (ADDR_EXPR, NULL_TREE,
                                     unchecked_convert (gnu_real_ret_type,
                                                        gnu_target,
                                                        false)),
                     NULL_TREE);

    }

  /* The only way we can be making a call via an access type is if Name is an
     explicit dereference.  In that case, get the list of formal args from the
     type the access type is pointing to.  Otherwise, get the formals from
     entity being called.  */
  if (Nkind (Name (gnat_node)) == N_Explicit_Dereference)
    gnat_formal = First_Formal_With_Extras (Etype (Name (gnat_node)));
  else if (Nkind (Name (gnat_node)) == N_Attribute_Reference)
    /* Assume here that this must be 'Elab_Body or 'Elab_Spec.  */
    gnat_formal = 0;
  else
    gnat_formal = First_Formal_With_Extras (Entity (Name (gnat_node)));

  /* Create the list of the actual parameters as GCC expects it, namely a chain
     of TREE_LIST nodes in which the TREE_VALUE field of each node is a
     parameter-expression and the TREE_PURPOSE field is null.  Skip Out
     parameters not passed by reference and don't need to be copied in.  */
  for (gnat_actual = First_Actual (gnat_node);
       Present (gnat_actual);
       gnat_formal = Next_Formal_With_Extras (gnat_formal),
       gnat_actual = Next_Actual (gnat_actual))
    {
      tree gnu_formal
        = (present_gnu_tree (gnat_formal)
           ? get_gnu_tree (gnat_formal) : NULL_TREE);
      tree gnu_formal_type = gnat_to_gnu_type (Etype (gnat_formal));
      /* We must suppress conversions that can cause the creation of a
         temporary in the Out or In Out case because we need the real
         object in this case, either to pass its address if it's passed
         by reference or as target of the back copy done after the call
         if it uses the copy-in copy-out mechanism.  We do it in the In
         case too, except for an unchecked conversion because it alone
         can cause the actual to be misaligned and the addressability
         test is applied to the real object.  */
      bool suppress_type_conversion
        = ((Nkind (gnat_actual) == N_Unchecked_Type_Conversion
            && Ekind (gnat_formal) != E_In_Parameter)
           || (Nkind (gnat_actual) == N_Type_Conversion
               && Is_Composite_Type (Underlying_Type (Etype (gnat_formal)))));
      Node_Id gnat_name = (suppress_type_conversion
                           ? Expression (gnat_actual) : gnat_actual);
      tree gnu_name = gnat_to_gnu (gnat_name), gnu_name_type;
      tree gnu_actual;

      /* If it's possible we may need to use this expression twice, make sure
         that any side-effects are handled via SAVE_EXPRs.  Likewise if we need
         to force side-effects before the call.
         ??? This is more conservative than we need since we don't need to do
         this for pass-by-ref with no conversion.  */
      if (Ekind (gnat_formal) != E_In_Parameter)
        gnu_name = gnat_stabilize_reference (gnu_name, true);

      /* If we are passing a non-addressable parameter by reference, pass the
         address of a copy.  In the Out or In Out case, set up to copy back
         out after the call.  */
      if (gnu_formal
          && (DECL_BY_REF_P (gnu_formal)
              || (TREE_CODE (gnu_formal) == PARM_DECL
                  && (DECL_BY_COMPONENT_PTR_P (gnu_formal)
                      || (DECL_BY_DESCRIPTOR_P (gnu_formal)))))
          && (gnu_name_type = gnat_to_gnu_type (Etype (gnat_name)))
          && !addressable_p (gnu_name, gnu_name_type))
        {
          tree gnu_copy = gnu_name, gnu_temp;

          /* If the type is by_reference, a copy is not allowed.  */
          if (Is_By_Reference_Type (Etype (gnat_formal)))
            post_error
              ("misaligned actual cannot be passed by reference", gnat_actual);

          /* For users of Starlet we issue a warning because the
             interface apparently assumes that by-ref parameters
             outlive the procedure invocation.  The code still
             will not work as intended, but we cannot do much
             better since other low-level parts of the back-end
             would allocate temporaries at will because of the
             misalignment if we did not do so here.  */
          else if (Is_Valued_Procedure (Entity (Name (gnat_node))))
            {
              post_error
                ("?possible violation of implicit assumption", gnat_actual);
              post_error_ne
                ("?made by pragma Import_Valued_Procedure on &", gnat_actual,
                 Entity (Name (gnat_node)));
              post_error_ne ("?because of misalignment of &", gnat_actual,
                             gnat_formal);
            }

          /* Remove any unpadding from the object and reset the copy.  */
          if (TREE_CODE (gnu_name) == COMPONENT_REF
              && ((TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_name, 0)))
                   == RECORD_TYPE)
                  && (TYPE_IS_PADDING_P
                      (TREE_TYPE (TREE_OPERAND (gnu_name, 0))))))
            gnu_name = gnu_copy = TREE_OPERAND (gnu_name, 0);

          /* Otherwise convert to the nominal type of the object if it's
             a record type.  There are several cases in which we need to
             make the temporary using this type instead of the actual type
             of the object if they are distinct, because the expectations
             of the callee would otherwise not be met:
               - if it's a justified modular type,
               - if the actual type is a smaller packable version of it.  */
          else if (TREE_CODE (gnu_name_type) == RECORD_TYPE
                   && (TYPE_JUSTIFIED_MODULAR_P (gnu_name_type)
                       || smaller_packable_type_p (TREE_TYPE (gnu_name),
                                                 gnu_name_type)))
            gnu_name = convert (gnu_name_type, gnu_name);

          /* Make a SAVE_EXPR to both properly account for potential side
             effects and handle the creation of a temporary copy.  Special
             code in gnat_gimplify_expr ensures that the same temporary is
             used as the object and copied back after the call if needed.  */
          gnu_name = build1 (SAVE_EXPR, TREE_TYPE (gnu_name), gnu_name);
          TREE_SIDE_EFFECTS (gnu_name) = 1;

          /* Set up to move the copy back to the original.  */
          if (Ekind (gnat_formal) != E_In_Parameter)
            {
              gnu_temp = build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_copy,
                                          gnu_name);
              set_expr_location_from_node (gnu_temp, gnat_actual);
              append_to_statement_list (gnu_temp, &gnu_after_list);
            }
        }

      /* Start from the real object and build the actual.  */
      gnu_actual = gnu_name;

      /* If this was a procedure call, we may not have removed any padding.
         So do it here for the part we will use as an input, if any.  */
      if (Ekind (gnat_formal) != E_Out_Parameter
          && TREE_CODE (TREE_TYPE (gnu_actual)) == RECORD_TYPE
          && TYPE_IS_PADDING_P (TREE_TYPE (gnu_actual)))
        gnu_actual = convert (get_unpadded_type (Etype (gnat_actual)),
                              gnu_actual);

      /* Do any needed conversions for the actual and make sure that it is
         in range of the formal's type.  */
      if (suppress_type_conversion)
        {
          /* Put back the conversion we suppressed above in the computation
             of the real object.  Note that we treat a conversion between
             aggregate types as if it is an unchecked conversion here.  */
          gnu_actual
            = unchecked_convert (gnat_to_gnu_type (Etype (gnat_actual)),
                                 gnu_actual,
                                 (Nkind (gnat_actual)
                                  == N_Unchecked_Type_Conversion)
                                 && No_Truncation (gnat_actual));

          if (Ekind (gnat_formal) != E_Out_Parameter
              && Do_Range_Check (gnat_actual))
            gnu_actual = emit_range_check (gnu_actual, Etype (gnat_formal));
        }
      else
        {
          if (Ekind (gnat_formal) != E_Out_Parameter
              && Do_Range_Check (gnat_actual))
            gnu_actual = emit_range_check (gnu_actual, Etype (gnat_formal));

          /* We may have suppressed a conversion to the Etype of the actual
             since the parent is a procedure call.  So put it back here.
             ??? We use the reverse order compared to the case above because
             of an awkward interaction with the check and actually don't put
             back the conversion at all if a check is emitted.  This is also
             done for the conversion to the formal's type just below.  */
          if (TREE_CODE (gnu_actual) != SAVE_EXPR)
            gnu_actual = convert (gnat_to_gnu_type (Etype (gnat_actual)),
                                  gnu_actual);
        }

      if (TREE_CODE (gnu_actual) != SAVE_EXPR)
        gnu_actual = convert (gnu_formal_type, gnu_actual);

      /* Unless this is an In parameter, we must remove any justified modular
         building from GNU_NAME to get an lvalue.  */
      if (Ekind (gnat_formal) != E_In_Parameter
          && TREE_CODE (gnu_name) == CONSTRUCTOR
          && TREE_CODE (TREE_TYPE (gnu_name)) == RECORD_TYPE
          && TYPE_JUSTIFIED_MODULAR_P (TREE_TYPE (gnu_name)))
        gnu_name = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_name))),
                            gnu_name);

      /* If we have not saved a GCC object for the formal, it means it is an
         Out parameter not passed by reference and that does not need to be
         copied in. Otherwise, look at the PARM_DECL to see if it is passed by
         reference. */
      if (gnu_formal
          && TREE_CODE (gnu_formal) == PARM_DECL
          && DECL_BY_REF_P (gnu_formal))
        {
          if (Ekind (gnat_formal) != E_In_Parameter)
            {
              /* In Out or Out parameters passed by reference don't use the
                 copy-in copy-out mechanism so the address of the real object
                 must be passed to the function.  */
              gnu_actual = gnu_name;

              /* If we have a padded type, be sure we've removed padding.  */
              if (TREE_CODE (TREE_TYPE (gnu_actual)) == RECORD_TYPE
                  && TYPE_IS_PADDING_P (TREE_TYPE (gnu_actual))
                  && TREE_CODE (gnu_actual) != SAVE_EXPR)
                gnu_actual = convert (get_unpadded_type (Etype (gnat_actual)),
                                      gnu_actual);

              /* If we have the constructed subtype of an aliased object
                 with an unconstrained nominal subtype, the type of the
                 actual includes the template, although it is formally
                 constrained.  So we need to convert it back to the real
                 constructed subtype to retrieve the constrained part
                 and takes its address.  */
              if (TREE_CODE (TREE_TYPE (gnu_actual)) == RECORD_TYPE
                  && TYPE_CONTAINS_TEMPLATE_P (TREE_TYPE (gnu_actual))
                  && TREE_CODE (gnu_actual) != SAVE_EXPR
                  && Is_Constr_Subt_For_UN_Aliased (Etype (gnat_actual))
                  && Is_Array_Type (Etype (gnat_actual)))
                gnu_actual = convert (gnat_to_gnu_type (Etype (gnat_actual)),
                                      gnu_actual);
            }

          /* The symmetry of the paths to the type of an entity is broken here
             since arguments don't know that they will be passed by ref. */
          gnu_formal_type = TREE_TYPE (get_gnu_tree (gnat_formal));
          gnu_actual = build_unary_op (ADDR_EXPR, gnu_formal_type, gnu_actual);
        }
      else if (gnu_formal
               && TREE_CODE (gnu_formal) == PARM_DECL
               && DECL_BY_COMPONENT_PTR_P (gnu_formal))
        {
          gnu_formal_type = TREE_TYPE (get_gnu_tree (gnat_formal));
          gnu_actual = maybe_implicit_deref (gnu_actual);
          gnu_actual = maybe_unconstrained_array (gnu_actual);

          if (TREE_CODE (gnu_formal_type) == RECORD_TYPE
              && TYPE_IS_PADDING_P (gnu_formal_type))
            {
              gnu_formal_type = TREE_TYPE (TYPE_FIELDS (gnu_formal_type));
              gnu_actual = convert (gnu_formal_type, gnu_actual);
            }

          /* Take the address of the object and convert to the proper pointer
             type.  We'd like to actually compute the address of the beginning
             of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
             possibility that the ARRAY_REF might return a constant and we'd be
             getting the wrong address.  Neither approach is exactly correct,
             but this is the most likely to work in all cases.  */
          gnu_actual = convert (gnu_formal_type,
                                build_unary_op (ADDR_EXPR, NULL_TREE,
                                                gnu_actual));
        }
      else if (gnu_formal
               && TREE_CODE (gnu_formal) == PARM_DECL
               && DECL_BY_DESCRIPTOR_P (gnu_formal))
        {
          /* If arg is 'Null_Parameter, pass zero descriptor.  */
          if ((TREE_CODE (gnu_actual) == INDIRECT_REF
               || TREE_CODE (gnu_actual) == UNCONSTRAINED_ARRAY_REF)
              && TREE_PRIVATE (gnu_actual))
            gnu_actual = convert (DECL_ARG_TYPE (get_gnu_tree (gnat_formal)),
                                  integer_zero_node);
          else
            gnu_actual = build_unary_op (ADDR_EXPR, NULL_TREE,
                                         fill_vms_descriptor (gnu_actual,
                                                              gnat_formal));
        }
      else
        {
          tree gnu_actual_size = TYPE_SIZE (TREE_TYPE (gnu_actual));

          if (Ekind (gnat_formal) != E_In_Parameter)
            gnu_name_list = tree_cons (NULL_TREE, gnu_name, gnu_name_list);

          if (!gnu_formal || TREE_CODE (gnu_formal) != PARM_DECL)
            continue;

          /* If this is 'Null_Parameter, pass a zero even though we are
             dereferencing it.  */
          else if (TREE_CODE (gnu_actual) == INDIRECT_REF
                   && TREE_PRIVATE (gnu_actual)
                   && host_integerp (gnu_actual_size, 1)
                   && 0 >= compare_tree_int (gnu_actual_size,
                                                   BITS_PER_WORD))
            gnu_actual
              = unchecked_convert (DECL_ARG_TYPE (gnu_formal),
                                   convert (gnat_type_for_size
                                            (tree_low_cst (gnu_actual_size, 1),
                                             1),
                                            integer_zero_node),
                                   false);
          else
            gnu_actual = convert (DECL_ARG_TYPE (gnu_formal), gnu_actual);
        }

      gnu_actual_list = tree_cons (NULL_TREE, gnu_actual, gnu_actual_list);
    }

  gnu_subprog_call = build_call_list (TREE_TYPE (gnu_subprog_type),
                                      gnu_subprog_addr,
                                      nreverse (gnu_actual_list));
  set_expr_location_from_node (gnu_subprog_call, gnat_node);

  /* If we return by passing a target, the result is the target after the
     call.  We must not emit the call directly here because this might be
     evaluated as part of an expression with conditions to control whether
     the call should be emitted or not.  */
  if (TYPE_RETURNS_BY_TARGET_PTR_P (gnu_subprog_type))
    {
      /* Conceptually, what we need is a COMPOUND_EXPR with the call followed
         by the target object converted to the proper type.  Doing so would
         potentially be very inefficient, however, as this expression might
         end up wrapped into an outer SAVE_EXPR later on, which would incur a
         pointless temporary copy of the whole object.

         What we do instead is build a COMPOUND_EXPR returning the address of
         the target, and then dereference.  Wrapping the COMPOUND_EXPR into a
         SAVE_EXPR later on then only incurs a pointer copy.  */

      tree gnu_result_type
        = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (gnu_subprog_type)));

      /* Build and return
         (result_type) *[gnu_subprog_call (&gnu_target, ...), &gnu_target]  */

      tree gnu_target_address
        = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_target);
      set_expr_location_from_node (gnu_target_address, gnat_node);

      gnu_result
        = build2 (COMPOUND_EXPR, TREE_TYPE (gnu_target_address),
                  gnu_subprog_call, gnu_target_address);

      gnu_result
        = unchecked_convert (gnu_result_type,
                             build_unary_op (INDIRECT_REF, NULL_TREE,
                                             gnu_result),
                             false);

      *gnu_result_type_p = gnu_result_type;
      return gnu_result;
    }

  /* If it is a function call, the result is the call expression unless
     a target is specified, in which case we copy the result into the target
     and return the assignment statement.  */
  else if (Nkind (gnat_node) == N_Function_Call)
    {
      gnu_result = gnu_subprog_call;

      /* If the function returns an unconstrained array or by reference,
         we have to de-dereference the pointer.  */
      if (TYPE_RETURNS_UNCONSTRAINED_P (gnu_subprog_type)
          || TYPE_RETURNS_BY_REF_P (gnu_subprog_type))
        gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE, gnu_result);

      if (gnu_target)
        gnu_result = build_binary_op (MODIFY_EXPR, NULL_TREE,
                                      gnu_target, gnu_result);
      else
        *gnu_result_type_p = get_unpadded_type (Etype (gnat_node));

      return gnu_result;
    }

  /* If this is the case where the GNAT tree contains a procedure call
     but the Ada procedure has copy in copy out parameters, the special
     parameter passing mechanism must be used.  */
  else if (TYPE_CI_CO_LIST (gnu_subprog_type) != NULL_TREE)
    {
      /* List of FIELD_DECLs associated with the PARM_DECLs of the copy
         in copy out parameters.  */
      tree scalar_return_list = TYPE_CI_CO_LIST (gnu_subprog_type);
      int length = list_length (scalar_return_list);

      if (length > 1)
        {
          tree gnu_name;

          gnu_subprog_call = save_expr (gnu_subprog_call);
          gnu_name_list = nreverse (gnu_name_list);

          /* If any of the names had side-effects, ensure they are all
             evaluated before the call.  */
          for (gnu_name = gnu_name_list; gnu_name;
               gnu_name = TREE_CHAIN (gnu_name))
            if (TREE_SIDE_EFFECTS (TREE_VALUE (gnu_name)))
              append_to_statement_list (TREE_VALUE (gnu_name),
                                        &gnu_before_list);
        }

      if (Nkind (Name (gnat_node)) == N_Explicit_Dereference)
        gnat_formal = First_Formal_With_Extras (Etype (Name (gnat_node)));
      else
        gnat_formal = First_Formal_With_Extras (Entity (Name (gnat_node)));

      for (gnat_actual = First_Actual (gnat_node);
           Present (gnat_actual);
           gnat_formal = Next_Formal_With_Extras (gnat_formal),
           gnat_actual = Next_Actual (gnat_actual))
        /* If we are dealing with a copy in copy out parameter, we must
           retrieve its value from the record returned in the call.  */
        if (!(present_gnu_tree (gnat_formal)
              && TREE_CODE (get_gnu_tree (gnat_formal)) == PARM_DECL
              && (DECL_BY_REF_P (get_gnu_tree (gnat_formal))
                  || (TREE_CODE (get_gnu_tree (gnat_formal)) == PARM_DECL
                      && ((DECL_BY_COMPONENT_PTR_P (get_gnu_tree (gnat_formal))
                           || (DECL_BY_DESCRIPTOR_P
                               (get_gnu_tree (gnat_formal))))))))
            && Ekind (gnat_formal) != E_In_Parameter)
          {
            /* Get the value to assign to this Out or In Out parameter.  It is
               either the result of the function if there is only a single such
               parameter or the appropriate field from the record returned.  */
            tree gnu_result
              = length == 1 ? gnu_subprog_call
                : build_component_ref (gnu_subprog_call, NULL_TREE,
                                       TREE_PURPOSE (scalar_return_list),
                                       false);

            /* If the actual is a conversion, get the inner expression, which
               will be the real destination, and convert the result to the
               type of the actual parameter.  */
            tree gnu_actual
              = maybe_unconstrained_array (TREE_VALUE (gnu_name_list));

            /* If the result is a padded type, remove the padding.  */
            if (TREE_CODE (TREE_TYPE (gnu_result)) == RECORD_TYPE
                && TYPE_IS_PADDING_P (TREE_TYPE (gnu_result)))
              gnu_result = convert (TREE_TYPE (TYPE_FIELDS
                                               (TREE_TYPE (gnu_result))),
                                    gnu_result);

            /* If the actual is a type conversion, the real target object is
               denoted by the inner Expression and we need to convert the
               result to the associated type.
               We also need to convert our gnu assignment target to this type
               if the corresponding GNU_NAME was constructed from the GNAT
               conversion node and not from the inner Expression.  */
            if (Nkind (gnat_actual) == N_Type_Conversion)
              {
                gnu_result
                  = convert_with_check
                    (Etype (Expression (gnat_actual)), gnu_result,
                     Do_Overflow_Check (gnat_actual),
                     Do_Range_Check (Expression (gnat_actual)),
                     Float_Truncate (gnat_actual));

                if (!Is_Composite_Type (Underlying_Type (Etype (gnat_formal))))
                  gnu_actual = convert (TREE_TYPE (gnu_result), gnu_actual);
              }

            /* Unchecked conversions as actuals for Out parameters are not
               allowed in user code because they are not variables, but do
               occur in front-end expansions.  The associated GNU_NAME is
               always obtained from the inner expression in such cases.  */
            else if (Nkind (gnat_actual) == N_Unchecked_Type_Conversion)
              gnu_result = unchecked_convert (TREE_TYPE (gnu_actual),
                                              gnu_result,
                                              No_Truncation (gnat_actual));
            else
              {
                if (Do_Range_Check (gnat_actual))
                  gnu_result = emit_range_check (gnu_result,
                                                 Etype (gnat_actual));

                if (!(!TREE_CONSTANT (TYPE_SIZE (TREE_TYPE (gnu_actual)))
                      && TREE_CONSTANT (TYPE_SIZE (TREE_TYPE (gnu_result)))))
                  gnu_result = convert (TREE_TYPE (gnu_actual), gnu_result);
              }

            gnu_result = build_binary_op (MODIFY_EXPR, NULL_TREE,
                                          gnu_actual, gnu_result);
            set_expr_location_from_node (gnu_result, gnat_actual);
            append_to_statement_list (gnu_result, &gnu_before_list);
            scalar_return_list = TREE_CHAIN (scalar_return_list);
            gnu_name_list = TREE_CHAIN (gnu_name_list);
          }
        }
  else
    append_to_statement_list (gnu_subprog_call, &gnu_before_list);

  append_to_statement_list (gnu_after_list, &gnu_before_list);
  return gnu_before_list;
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, an
   N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned.  */

static tree
Handled_Sequence_Of_Statements_to_gnu (Node_Id gnat_node)
{
  tree gnu_jmpsave_decl = NULL_TREE;
  tree gnu_jmpbuf_decl = NULL_TREE;
  /* If just annotating, ignore all EH and cleanups.  */
  bool gcc_zcx = (!type_annotate_only
                  && Present (Exception_Handlers (gnat_node))
                  && Exception_Mechanism == Back_End_Exceptions);
  bool setjmp_longjmp
    = (!type_annotate_only && Present (Exception_Handlers (gnat_node))
       && Exception_Mechanism == Setjmp_Longjmp);
  bool at_end = !type_annotate_only && Present (At_End_Proc (gnat_node));
  bool binding_for_block = (at_end || gcc_zcx || setjmp_longjmp);
  tree gnu_inner_block; /* The statement(s) for the block itself.  */
  tree gnu_result;
  tree gnu_expr;
  Node_Id gnat_temp;

  /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
     and we have our own SJLJ mechanism.  To call the GCC mechanism, we call
     add_cleanup, and when we leave the binding, end_stmt_group will create
     the TRY_FINALLY_EXPR.

     ??? The region level calls down there have been specifically put in place
     for a ZCX context and currently the order in which things are emitted
     (region/handlers) is different from the SJLJ case. Instead of putting
     other calls with different conditions at other places for the SJLJ case,
     it seems cleaner to reorder things for the SJLJ case and generalize the
     condition to make it not ZCX specific.

     If there are any exceptions or cleanup processing involved, we need an
     outer statement group (for Setjmp_Longjmp) and binding level.  */
  if (binding_for_block)
    {
      start_stmt_group ();
      gnat_pushlevel ();
    }

  /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
     area for address of previous buffer.  Do this first since we need to have
     the setjmp buf known for any decls in this block.  */
  if (setjmp_longjmp)
    {
      gnu_jmpsave_decl = create_var_decl (get_identifier ("JMPBUF_SAVE"),
                                          NULL_TREE, jmpbuf_ptr_type,
                                          build_call_0_expr (get_jmpbuf_decl),
                                          false, false, false, false, NULL,
                                          gnat_node);
      DECL_ARTIFICIAL (gnu_jmpsave_decl) = 1;

      /* The __builtin_setjmp receivers will immediately reinstall it.  Now
         because of the unstructured form of EH used by setjmp_longjmp, there
         might be forward edges going to __builtin_setjmp receivers on which
         it is uninitialized, although they will never be actually taken.  */
      TREE_NO_WARNING (gnu_jmpsave_decl) = 1;
      gnu_jmpbuf_decl = create_var_decl (get_identifier ("JMP_BUF"),
                                         NULL_TREE, jmpbuf_type,
                                         NULL_TREE, false, false, false, false,
                                         NULL, gnat_node);
      DECL_ARTIFICIAL (gnu_jmpbuf_decl) = 1;

      set_block_jmpbuf_decl (gnu_jmpbuf_decl);

      /* When we exit this block, restore the saved value.  */
      add_cleanup (build_call_1_expr (set_jmpbuf_decl, gnu_jmpsave_decl),
                   End_Label (gnat_node));
    }

  /* If we are to call a function when exiting this block, add a cleanup
     to the binding level we made above.  Note that add_cleanup is FIFO
     so we must register this cleanup after the EH cleanup just above.  */
  if (at_end)
    add_cleanup (build_call_0_expr (gnat_to_gnu (At_End_Proc (gnat_node))),
                 End_Label (gnat_node));

  /* Now build the tree for the declarations and statements inside this block.
     If this is SJLJ, set our jmp_buf as the current buffer.  */
  start_stmt_group ();

  if (setjmp_longjmp)
    add_stmt (build_call_1_expr (set_jmpbuf_decl,
                                 build_unary_op (ADDR_EXPR, NULL_TREE,
                                                 gnu_jmpbuf_decl)));

  if (Present (First_Real_Statement (gnat_node)))
    process_decls (Statements (gnat_node), Empty,
                   First_Real_Statement (gnat_node), true, true);

  /* Generate code for each statement in the block.  */
  for (gnat_temp = (Present (First_Real_Statement (gnat_node))
                    ? First_Real_Statement (gnat_node)
                    : First (Statements (gnat_node)));
       Present (gnat_temp); gnat_temp = Next (gnat_temp))
    add_stmt (gnat_to_gnu (gnat_temp));
  gnu_inner_block = end_stmt_group ();

  /* Now generate code for the two exception models, if either is relevant for
     this block.  */
  if (setjmp_longjmp)
    {
      tree *gnu_else_ptr = 0;
      tree gnu_handler;

      /* Make a binding level for the exception handling declarations and code
         and set up gnu_except_ptr_stack for the handlers to use.  */
      start_stmt_group ();
      gnat_pushlevel ();

      push_stack (&gnu_except_ptr_stack, NULL_TREE,
                  create_var_decl (get_identifier ("EXCEPT_PTR"),
                                   NULL_TREE,
                                   build_pointer_type (except_type_node),
                                   build_call_0_expr (get_excptr_decl), false,
                                   false, false, false, NULL, gnat_node));

      /* Generate code for each handler. The N_Exception_Handler case does the
         real work and returns a COND_EXPR for each handler, which we chain
         together here.  */
      for (gnat_temp = First_Non_Pragma (Exception_Handlers (gnat_node));
           Present (gnat_temp); gnat_temp = Next_Non_Pragma (gnat_temp))
        {
          gnu_expr = gnat_to_gnu (gnat_temp);

          /* If this is the first one, set it as the outer one. Otherwise,
             point the "else" part of the previous handler to us. Then point
             to our "else" part.  */
          if (!gnu_else_ptr)
            add_stmt (gnu_expr);
          else
            *gnu_else_ptr = gnu_expr;

          gnu_else_ptr = &COND_EXPR_ELSE (gnu_expr);
        }

      /* If none of the exception handlers did anything, re-raise but do not
         defer abortion.  */
      gnu_expr = build_call_1_expr (raise_nodefer_decl,
                                    TREE_VALUE (gnu_except_ptr_stack));
      set_expr_location_from_node (gnu_expr, gnat_node);

      if (gnu_else_ptr)
        *gnu_else_ptr = gnu_expr;
      else
        add_stmt (gnu_expr);

      /* End the binding level dedicated to the exception handlers and get the
         whole statement group.  */
      pop_stack (&gnu_except_ptr_stack);
      gnat_poplevel ();
      gnu_handler = end_stmt_group ();

      /* If the setjmp returns 1, we restore our incoming longjmp value and
         then check the handlers.  */
      start_stmt_group ();
      add_stmt_with_node (build_call_1_expr (set_jmpbuf_decl,
                                             gnu_jmpsave_decl),
                          gnat_node);
      add_stmt (gnu_handler);
      gnu_handler = end_stmt_group ();

      /* This block is now "if (setjmp) ... <handlers> else <block>".  */
      gnu_result = build3 (COND_EXPR, void_type_node,
                           (build_call_1_expr
                            (setjmp_decl,
                             build_unary_op (ADDR_EXPR, NULL_TREE,
                                             gnu_jmpbuf_decl))),
                           gnu_handler, gnu_inner_block);
    }
  else if (gcc_zcx)
    {
      tree gnu_handlers;

      /* First make a block containing the handlers.  */
      start_stmt_group ();
      for (gnat_temp = First_Non_Pragma (Exception_Handlers (gnat_node));
           Present (gnat_temp);
           gnat_temp = Next_Non_Pragma (gnat_temp))
        add_stmt (gnat_to_gnu (gnat_temp));
      gnu_handlers = end_stmt_group ();

      /* Now make the TRY_CATCH_EXPR for the block.  */
      gnu_result = build2 (TRY_CATCH_EXPR, void_type_node,
                           gnu_inner_block, gnu_handlers);
    }
  else
    gnu_result = gnu_inner_block;

  /* Now close our outer block, if we had to make one.  */
  if (binding_for_block)
    {
      add_stmt (gnu_result);
      gnat_poplevel ();
      gnu_result = end_stmt_group ();
    }

  return gnu_result;
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
   to a GCC tree, which is returned.  This is the variant for Setjmp_Longjmp
   exception handling.  */

static tree
Exception_Handler_to_gnu_sjlj (Node_Id gnat_node)
{
  /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
     an "if" statement to select the proper exceptions.  For "Others", exclude
     exceptions where Handled_By_Others is nonzero unless the All_Others flag
     is set. For "Non-ada", accept an exception if "Lang" is 'V'.  */
  tree gnu_choice = integer_zero_node;
  tree gnu_body = build_stmt_group (Statements (gnat_node), false);
  Node_Id gnat_temp;

  for (gnat_temp = First (Exception_Choices (gnat_node));
       gnat_temp; gnat_temp = Next (gnat_temp))
    {
      tree this_choice;

      if (Nkind (gnat_temp) == N_Others_Choice)
        {
          if (All_Others (gnat_temp))
            this_choice = integer_one_node;
          else
            this_choice
              = build_binary_op
                (EQ_EXPR, integer_type_node,
                 convert
                 (integer_type_node,
                  build_component_ref
                  (build_unary_op
                   (INDIRECT_REF, NULL_TREE,
                    TREE_VALUE (gnu_except_ptr_stack)),
                   get_identifier ("not_handled_by_others"), NULL_TREE,
                   false)),
                 integer_zero_node);
        }

      else if (Nkind (gnat_temp) == N_Identifier
               || Nkind (gnat_temp) == N_Expanded_Name)
        {
          Entity_Id gnat_ex_id = Entity (gnat_temp);
          tree gnu_expr;

          /* Exception may be a renaming. Recover original exception which is
             the one elaborated and registered.  */
          if (Present (Renamed_Object (gnat_ex_id)))
            gnat_ex_id = Renamed_Object (gnat_ex_id);

          gnu_expr = gnat_to_gnu_entity (gnat_ex_id, NULL_TREE, 0);

          this_choice
            = build_binary_op
              (EQ_EXPR, integer_type_node, TREE_VALUE (gnu_except_ptr_stack),
               convert (TREE_TYPE (TREE_VALUE (gnu_except_ptr_stack)),
                        build_unary_op (ADDR_EXPR, NULL_TREE, gnu_expr)));

          /* If this is the distinguished exception "Non_Ada_Error" (and we are
             in VMS mode), also allow a non-Ada exception (a VMS condition) t
             match.  */
          if (Is_Non_Ada_Error (Entity (gnat_temp)))
            {
              tree gnu_comp
                = build_component_ref
                  (build_unary_op (INDIRECT_REF, NULL_TREE,
                                   TREE_VALUE (gnu_except_ptr_stack)),
                   get_identifier ("lang"), NULL_TREE, false);

              this_choice
                = build_binary_op
                  (TRUTH_ORIF_EXPR, integer_type_node,
                   build_binary_op (EQ_EXPR, integer_type_node, gnu_comp,
                                    build_int_cst (TREE_TYPE (gnu_comp), 'V')),
                   this_choice);
            }
        }
      else
        gcc_unreachable ();

      gnu_choice = build_binary_op (TRUTH_ORIF_EXPR, integer_type_node,
                                    gnu_choice, this_choice);
    }

  return build3 (COND_EXPR, void_type_node, gnu_choice, gnu_body, NULL_TREE);
}
\f
/* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
   to a GCC tree, which is returned.  This is the variant for ZCX.  */

static tree
Exception_Handler_to_gnu_zcx (Node_Id gnat_node)
{
  tree gnu_etypes_list = NULL_TREE;
  tree gnu_expr;
  tree gnu_etype;
  tree gnu_current_exc_ptr;
  tree gnu_incoming_exc_ptr;
  Node_Id gnat_temp;

  /* We build a TREE_LIST of nodes representing what exception types this
     handler can catch, with special cases for others and all others cases.

     Each exception type is actually identified by a pointer to the exception
     id, or to a dummy object for "others" and "all others".

     Care should be taken to ensure that the control flow impact of "others"
     and "all others" is known to GCC. lang_eh_type_covers is doing the trick
     currently.  */
  for (gnat_temp = First (Exception_Choices (gnat_node));
       gnat_temp; gnat_temp = Next (gnat_temp))
    {
      if (Nkind (gnat_temp) == N_Others_Choice)
        {
          tree gnu_expr
            = All_Others (gnat_temp) ? all_others_decl : others_decl;

          gnu_etype
            = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_expr);
        }
      else if (Nkind (gnat_temp) == N_Identifier
               || Nkind (gnat_temp) == N_Expanded_Name)
        {
          Entity_Id gnat_ex_id = Entity (gnat_temp);

          /* Exception may be a renaming. Recover original exception which is
             the one elaborated and registered.  */
          if (Present (Renamed_Object (gnat_ex_id)))
            gnat_ex_id = Renamed_Object (gnat_ex_id);

          gnu_expr = gnat_to_gnu_entity (gnat_ex_id, NULL_TREE, 0);
          gnu_etype = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_expr);

          /* The Non_Ada_Error case for VMS exceptions is handled
             by the personality routine.  */
        }
      else
        gcc_unreachable ();

      /* The GCC interface expects NULL to be passed for catch all handlers, so
         it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
         is integer_zero_node.  It would not work, however, because GCC's
         notion of "catch all" is stronger than our notion of "others".  Until
         we correctly use the cleanup interface as well, doing that would
         prevent the "all others" handlers from being seen, because nothing
         can be caught beyond a catch all from GCC's point of view.  */
      gnu_etypes_list = tree_cons (NULL_TREE, gnu_etype, gnu_etypes_list);
    }

  start_stmt_group ();
  gnat_pushlevel ();

  /* Expand a call to the begin_handler hook at the beginning of the handler,
     and arrange for a call to the end_handler hook to occur on every possible
     exit path.

     The hooks expect a pointer to the low level occurrence. This is required
     for our stack management scheme because a raise inside the handler pushes
     a new occurrence on top of the stack, which means that this top does not
     necessarily match the occurrence this handler was dealing with.

     The EXC_PTR_EXPR object references the exception occurrence being
     propagated. Upon handler entry, this is the exception for which the
     handler is triggered. This might not be the case upon handler exit,
     however, as we might have a new occurrence propagated by the handler's
     body, and the end_handler hook called as a cleanup in this context.

     We use a local variable to retrieve the incoming value at handler entry
     time, and reuse it to feed the end_handler hook's argument at exit.  */
  gnu_current_exc_ptr = build0 (EXC_PTR_EXPR, ptr_type_node);
  gnu_incoming_exc_ptr = create_var_decl (get_identifier ("EXPTR"), NULL_TREE,
                                          ptr_type_node, gnu_current_exc_ptr,
                                          false, false, false, false, NULL,
                                          gnat_node);

  add_stmt_with_node (build_call_1_expr (begin_handler_decl,
                                         gnu_incoming_exc_ptr),
                      gnat_node);
  /* ??? We don't seem to have an End_Label at hand to set the location.  */
  add_cleanup (build_call_1_expr (end_handler_decl, gnu_incoming_exc_ptr),
               Empty);
  add_stmt_list (Statements (gnat_node));
  gnat_poplevel ();

  return build2 (CATCH_EXPR, void_type_node, gnu_etypes_list,
                 end_stmt_group ());
}
\f
/* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit.  */

static void
Compilation_Unit_to_gnu (Node_Id gnat_node)
{
  /* Make the decl for the elaboration procedure.  */
  bool body_p = (Defining_Entity (Unit (gnat_node)),
            Nkind (Unit (gnat_node)) == N_Package_Body
            || Nkind (Unit (gnat_node)) == N_Subprogram_Body);
  Entity_Id gnat_unit_entity = Defining_Entity (Unit (gnat_node));
  tree gnu_elab_proc_decl
    = create_subprog_decl
      (create_concat_name (gnat_unit_entity,
                           body_p ? "elabb" : "elabs"),
       NULL_TREE, void_ftype, NULL_TREE, false, true, false, NULL,
       gnat_unit_entity);
  struct elab_info *info;

  push_stack (&gnu_elab_proc_stack, NULL_TREE, gnu_elab_proc_decl);

  DECL_ELABORATION_PROC_P (gnu_elab_proc_decl) = 1;
  allocate_struct_function (gnu_elab_proc_decl, false);
  Sloc_to_locus (Sloc (gnat_unit_entity), &cfun->function_end_locus);
  set_cfun (NULL);

  /* For a body, first process the spec if there is one. */
  if (Nkind (Unit (gnat_node)) == N_Package_Body
      || (Nkind (Unit (gnat_node)) == N_Subprogram_Body
              && !Acts_As_Spec (gnat_node)))
    {
      add_stmt (gnat_to_gnu (Library_Unit (gnat_node)));
      finalize_from_with_types ();
    }

  process_inlined_subprograms (gnat_node);

  if (type_annotate_only && gnat_node == Cunit (Main_Unit))
    {
      elaborate_all_entities (gnat_node);

      if (Nkind (Unit (gnat_node)) == N_Subprogram_Declaration
          || Nkind (Unit (gnat_node)) == N_Generic_Package_Declaration
          || Nkind (Unit (gnat_node)) == N_Generic_Subprogram_Declaration)
        return;
    }

  process_decls (Declarations (Aux_Decls_Node (gnat_node)), Empty, Empty,
                 true, true);
  add_stmt (gnat_to_gnu (Unit (gnat_node)));

  /* Process any pragmas and actions following the unit.  */
  add_stmt_list (Pragmas_After (Aux_Decls_Node (gnat_node)));
  add_stmt_list (Actions (Aux_Decls_Node (gnat_node)));
  finalize_from_with_types ();

  /* Save away what we've made so far and record this potential elaboration
     procedure.  */
  info = (struct elab_info *) ggc_alloc (sizeof (struct elab_info));
  set_current_block_context (gnu_elab_proc_decl);
  gnat_poplevel ();
  DECL_SAVED_TREE (gnu_elab_proc_decl) = end_stmt_group ();
  info->next = elab_info_list;
  info->elab_proc = gnu_elab_proc_decl;
  info->gnat_node = gnat_node;
  elab_info_list = info;

  /* Generate elaboration code for this unit, if necessary, and say whether
     we did or not.  */
  pop_stack (&gnu_elab_proc_stack);

  /* Invalidate the global renaming pointers.  This is necessary because
     stabilization of the renamed entities may create SAVE_EXPRs which
     have been tied to a specific elaboration routine just above.  */
  invalidate_global_renaming_pointers ();
}
\f
/* This function is the driver of the GNAT to GCC tree transformation
   process.  It is the entry point of the tree transformer.  GNAT_NODE is the
   root of some GNAT tree.  Return the root of the corresponding GCC tree.
   If this is an expression, return the GCC equivalent of the expression.  If
   it is a statement, return the statement.  In the case when called for a
   statement, it may also add statements to the current statement group, in
   which case anything it returns is to be interpreted as occurring after
   anything `it already added.  */

tree
gnat_to_gnu (Node_Id gnat_node)
{
  bool went_into_elab_proc = false;
  tree gnu_result = error_mark_node; /* Default to no value. */
  tree gnu_result_type = void_type_node;
  tree gnu_expr;
  tree gnu_lhs, gnu_rhs;
  Node_Id gnat_temp;

  /* Save node number for error message and set location information.  */
  error_gnat_node = gnat_node;
  Sloc_to_locus (Sloc (gnat_node), &input_location);

  if (type_annotate_only
      && IN (Nkind (gnat_node), N_Statement_Other_Than_Procedure_Call))
    return alloc_stmt_list ();

  /* If this node is a non-static subexpression and we are only
     annotating types, make this into a NULL_EXPR.  */
  if (type_annotate_only
      && IN (Nkind (gnat_node), N_Subexpr)
      && Nkind (gnat_node) != N_Identifier
      && !Compile_Time_Known_Value (gnat_node))
    return build1 (NULL_EXPR, get_unpadded_type (Etype (gnat_node)),
                   build_call_raise (CE_Range_Check_Failed, gnat_node,
                                     N_Raise_Constraint_Error));

  /* If this is a Statement and we are at top level, it must be part of the
     elaboration procedure, so mark us as being in that procedure and push our
     context.

     If we are in the elaboration procedure, check if we are violating a
     No_Elaboration_Code restriction by having a statement there.  */
  if ((IN (Nkind (gnat_node), N_Statement_Other_Than_Procedure_Call)
       && Nkind (gnat_node) != N_Null_Statement)
      || Nkind (gnat_node) == N_Procedure_Call_Statement
      || Nkind (gnat_node) == N_Label
      || Nkind (gnat_node) == N_Implicit_Label_Declaration
      || Nkind (gnat_node) == N_Handled_Sequence_Of_Statements
      || ((Nkind (gnat_node) == N_Raise_Constraint_Error
           || Nkind (gnat_node) == N_Raise_Storage_Error
           || Nkind (gnat_node) == N_Raise_Program_Error)
          && (Ekind (Etype (gnat_node)) == E_Void)))
    {
      if (!current_function_decl)
        {
          current_function_decl = TREE_VALUE (gnu_elab_proc_stack);
          start_stmt_group ();
          gnat_pushlevel ();
          went_into_elab_proc = true;
        }

      /* Don't check for a possible No_Elaboration_Code restriction violation
         on N_Handled_Sequence_Of_Statements, as we want to signal an error on
         every nested real statement instead.  This also avoids triggering
         spurious errors on dummy (empty) sequences created by the front-end
         for package bodies in some cases.  */

      if (current_function_decl == TREE_VALUE (gnu_elab_proc_stack)
          && Nkind (gnat_node) != N_Handled_Sequence_Of_Statements)
        Check_Elaboration_Code_Allowed (gnat_node);
    }

  switch (Nkind (gnat_node))
    {
      /********************************/
      /* Chapter 2: Lexical Elements: */
      /********************************/

    case N_Identifier:
    case N_Expanded_Name:
    case N_Operator_Symbol:
    case N_Defining_Identifier:
      gnu_result = Identifier_to_gnu (gnat_node, &gnu_result_type);
      break;

    case N_Integer_Literal:
      {
        tree gnu_type;

        /* Get the type of the result, looking inside any padding and
           justified modular types.  Then get the value in that type.  */
        gnu_type = gnu_result_type = get_unpadded_type (Etype (gnat_node));

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

        gnu_result = UI_To_gnu (Intval (gnat_node), gnu_type);

        /* If the result overflows (meaning it doesn't fit in its base type),
           abort.  We would like to check that the value is within the range
           of the subtype, but that causes problems with subtypes whose usage
           will raise Constraint_Error and with biased representation, so
           we don't.  */
        gcc_assert (!TREE_OVERFLOW (gnu_result));
      }
      break;

    case N_Character_Literal:
      /* If a Entity is present, it means that this was one of the
         literals in a user-defined character type.  In that case,
         just return the value in the CONST_DECL.  Otherwise, use the
         character code.  In that case, the base type should be an
         INTEGER_TYPE, but we won't bother checking for that.  */
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      if (Present (Entity (gnat_node)))
        gnu_result = DECL_INITIAL (get_gnu_tree (Entity (gnat_node)));
      else
        gnu_result
          = build_int_cst_type
              (gnu_result_type, UI_To_CC (Char_Literal_Value (gnat_node)));
      break;

    case N_Real_Literal:
      /* If this is of a fixed-point type, the value we want is the
         value of the corresponding integer.  */
      if (IN (Ekind (Underlying_Type (Etype (gnat_node))), Fixed_Point_Kind))
        {
          gnu_result_type = get_unpadded_type (Etype (gnat_node));
          gnu_result = UI_To_gnu (Corresponding_Integer_Value (gnat_node),
                                  gnu_result_type);
          gcc_assert (!TREE_OVERFLOW (gnu_result));
        }

      /* We should never see a Vax_Float type literal, since the front end
         is supposed to transform these using appropriate conversions */
      else if (Vax_Float (Underlying_Type (Etype (gnat_node))))
        gcc_unreachable ();

      else
        {
          Ureal ur_realval = Realval (gnat_node);

          gnu_result_type = get_unpadded_type (Etype (gnat_node));

          /* If the real value is zero, so is the result.  Otherwise,
             convert it to a machine number if it isn't already.  That
             forces BASE to 0 or 2 and simplifies the rest of our logic.  */
          if (UR_Is_Zero (ur_realval))
            gnu_result = convert (gnu_result_type, integer_zero_node);
          else
            {
              if (!Is_Machine_Number (gnat_node))
                ur_realval
                  = Machine (Base_Type (Underlying_Type (Etype (gnat_node))),
                             ur_realval, Round_Even, gnat_node);

              gnu_result
                = UI_To_gnu (Numerator (ur_realval), gnu_result_type);

              /* If we have a base of zero, divide by the denominator.
                 Otherwise, the base must be 2 and we scale the value, which
                 we know can fit in the mantissa of the type (hence the use
                 of that type above).  */
              if (No (Rbase (ur_realval)))
                gnu_result
                  = build_binary_op (RDIV_EXPR,
                                     get_base_type (gnu_result_type),
                                     gnu_result,
                                     UI_To_gnu (Denominator (ur_realval),
                                                gnu_result_type));
              else
                {
                  REAL_VALUE_TYPE tmp;

                  gcc_assert (Rbase (ur_realval) == 2);
                  real_ldexp (&tmp, &TREE_REAL_CST (gnu_result),
                              - UI_To_Int (Denominator (ur_realval)));
                  gnu_result = build_real (gnu_result_type, tmp);
                }
            }

          /* Now see if we need to negate the result.  Do it this way to
             properly handle -0.  */
          if (UR_Is_Negative (Realval (gnat_node)))
            gnu_result
              = build_unary_op (NEGATE_EXPR, get_base_type (gnu_result_type),
                                gnu_result);
        }

      break;

    case N_String_Literal:
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      if (TYPE_PRECISION (TREE_TYPE (gnu_result_type)) == HOST_BITS_PER_CHAR)
        {
          String_Id gnat_string = Strval (gnat_node);
          int length = String_Length (gnat_string);
          int i;
          char *string;
          if (length >= ALLOCA_THRESHOLD)
             string = XNEWVEC (char, length + 1); /* in case of large strings */
          else
             string = (char *) alloca (length + 1);

          /* Build the string with the characters in the literal.  Note
             that Ada strings are 1-origin.  */
          for (i = 0; i < length; i++)
            string[i] = Get_String_Char (gnat_string, i + 1);

          /* Put a null at the end of the string in case it's in a context
             where GCC will want to treat it as a C string.  */
          string[i] = 0;

          gnu_result = build_string (length, string);

          /* Strings in GCC don't normally have types, but we want
             this to not be converted to the array type.  */
          TREE_TYPE (gnu_result) = gnu_result_type;

          if (length >= ALLOCA_THRESHOLD) /* free if heap-allocated */
             free (string);
        }
      else
        {
          /* Build a list consisting of each character, then make
             the aggregate.  */
          String_Id gnat_string = Strval (gnat_node);
          int length = String_Length (gnat_string);
          int i;
          tree gnu_list = NULL_TREE;
          tree gnu_idx = TYPE_MIN_VALUE (TYPE_DOMAIN (gnu_result_type));

          for (i = 0; i < length; i++)
            {
              gnu_list
                = tree_cons (gnu_idx,
                             build_int_cst (TREE_TYPE (gnu_result_type),
                                            Get_String_Char (gnat_string,
                                                             i + 1)),
                             gnu_list);

              gnu_idx = int_const_binop (PLUS_EXPR, gnu_idx, integer_one_node,
                                         0);
            }

          gnu_result
            = gnat_build_constructor (gnu_result_type, nreverse (gnu_list));
        }
      break;

    case N_Pragma:
      gnu_result = Pragma_to_gnu (gnat_node);
      break;

    /**************************************/
    /* Chapter 3: Declarations and Types: */
    /**************************************/

    case N_Subtype_Declaration:
    case N_Full_Type_Declaration:
    case N_Incomplete_Type_Declaration:
    case N_Private_Type_Declaration:
    case N_Private_Extension_Declaration:
    case N_Task_Type_Declaration:
      process_type (Defining_Entity (gnat_node));
      gnu_result = alloc_stmt_list ();
      break;

    case N_Object_Declaration:
    case N_Exception_Declaration:
      gnat_temp = Defining_Entity (gnat_node);
      gnu_result = alloc_stmt_list ();

      /* If we are just annotating types and this object has an unconstrained
         or task type, don't elaborate it.   */
      if (type_annotate_only
          && (((Is_Array_Type (Etype (gnat_temp))
                || Is_Record_Type (Etype (gnat_temp)))
               && !Is_Constrained (Etype (gnat_temp)))
            || Is_Concurrent_Type (Etype (gnat_temp))))
        break;

      if (Present (Expression (gnat_node))
          && !(Nkind (gnat_node) == N_Object_Declaration
               && No_Initialization (gnat_node))
          && (!type_annotate_only
              || Compile_Time_Known_Value (Expression (gnat_node))))
        {
          gnu_expr = gnat_to_gnu (Expression (gnat_node));
          if (Do_Range_Check (Expression (gnat_node)))
            gnu_expr = emit_range_check (gnu_expr, Etype (gnat_temp));

          /* If this object has its elaboration delayed, we must force
             evaluation of GNU_EXPR right now and save it for when the object
             is frozen.  */
          if (Present (Freeze_Node (gnat_temp)))
            {
              if ((Is_Public (gnat_temp) || global_bindings_p ())
                  && !TREE_CONSTANT (gnu_expr))
                gnu_expr
                  = create_var_decl (create_concat_name (gnat_temp, "init"),
                                     NULL_TREE, TREE_TYPE (gnu_expr),
                                     gnu_expr, false, Is_Public (gnat_temp),
                                     false, false, NULL, gnat_temp);
              else
                gnu_expr = maybe_variable (gnu_expr);

              save_gnu_tree (gnat_node, gnu_expr, true);
            }
        }
      else
        gnu_expr = NULL_TREE;

      if (type_annotate_only && gnu_expr && TREE_CODE (gnu_expr) == ERROR_MARK)
        gnu_expr = NULL_TREE;

      if (No (Freeze_Node (gnat_temp)))
        gnat_to_gnu_entity (gnat_temp, gnu_expr, 1);
      break;

    case N_Object_Renaming_Declaration:
      gnat_temp = Defining_Entity (gnat_node);

      /* Don't do anything if this renaming is handled by the front end or if
         we are just annotating types and this object has a composite or task
         type, don't elaborate it.  We return the result in case it has any
         SAVE_EXPRs in it that need to be evaluated here.  */
      if (!Is_Renaming_Of_Object (gnat_temp)
          && ! (type_annotate_only
                && (Is_Array_Type (Etype (gnat_temp))
                    || Is_Record_Type (Etype (gnat_temp))
                    || Is_Concurrent_Type (Etype (gnat_temp)))))
        gnu_result
          = gnat_to_gnu_entity (gnat_temp,
                                gnat_to_gnu (Renamed_Object (gnat_temp)), 1);
      else
        gnu_result = alloc_stmt_list ();
      break;

    case N_Implicit_Label_Declaration:
      gnat_to_gnu_entity (Defining_Entity (gnat_node), NULL_TREE, 1);
      gnu_result = alloc_stmt_list ();
      break;

    case N_Exception_Renaming_Declaration:
    case N_Number_Declaration:
    case N_Package_Renaming_Declaration:
    case N_Subprogram_Renaming_Declaration:
      /* These are fully handled in the front end.  */
      gnu_result = alloc_stmt_list ();
      break;

    /*************************************/
    /* Chapter 4: Names and Expressions: */
    /*************************************/

    case N_Explicit_Dereference:
      gnu_result = gnat_to_gnu (Prefix (gnat_node));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE, gnu_result);
      break;

    case N_Indexed_Component:
      {
        tree gnu_array_object = gnat_to_gnu (Prefix (gnat_node));
        tree gnu_type;
        int ndim;
        int i;
        Node_Id *gnat_expr_array;

        gnu_array_object = maybe_implicit_deref (gnu_array_object);
        gnu_array_object = maybe_unconstrained_array (gnu_array_object);

        /* If we got a padded type, remove it too.  */
        if (TREE_CODE (TREE_TYPE (gnu_array_object)) == RECORD_TYPE
            && TYPE_IS_PADDING_P (TREE_TYPE (gnu_array_object)))
          gnu_array_object
            = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_array_object))),
                       gnu_array_object);

        gnu_result = gnu_array_object;

        /* First compute the number of dimensions of the array, then
           fill the expression array, the order depending on whether
           this is a Convention_Fortran array or not.  */
        for (ndim = 1, gnu_type = TREE_TYPE (gnu_array_object);
             TREE_CODE (TREE_TYPE (gnu_type)) == ARRAY_TYPE
             && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_type));
             ndim++, gnu_type = TREE_TYPE (gnu_type))
          ;

        gnat_expr_array = (Node_Id *) alloca (ndim * sizeof (Node_Id));

        if (TYPE_CONVENTION_FORTRAN_P (TREE_TYPE (gnu_array_object)))
          for (i = ndim - 1, gnat_temp = First (Expressions (gnat_node));
               i >= 0;
               i--, gnat_temp = Next (gnat_temp))
            gnat_expr_array[i] = gnat_temp;
        else
          for (i = 0, gnat_temp = First (Expressions (gnat_node));
               i < ndim;
               i++, gnat_temp = Next (gnat_temp))
            gnat_expr_array[i] = gnat_temp;

        for (i = 0, gnu_type = TREE_TYPE (gnu_array_object);
             i < ndim; i++, gnu_type = TREE_TYPE (gnu_type))
          {
            gcc_assert (TREE_CODE (gnu_type) == ARRAY_TYPE);
            gnat_temp = gnat_expr_array[i];
            gnu_expr = gnat_to_gnu (gnat_temp);

            if (Do_Range_Check (gnat_temp))
              gnu_expr
                = emit_index_check
                  (gnu_array_object, gnu_expr,
                   TYPE_MIN_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type))),
                   TYPE_MAX_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type))));

            gnu_result = build_binary_op (ARRAY_REF, NULL_TREE,
                                          gnu_result, gnu_expr);
          }
      }

      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      break;

    case N_Slice:
      {
        tree gnu_type;
        Node_Id gnat_range_node = Discrete_Range (gnat_node);

        gnu_result = gnat_to_gnu (Prefix (gnat_node));
        gnu_result_type = get_unpadded_type (Etype (gnat_node));

        /* Do any implicit dereferences of the prefix and do any needed
           range check.  */
        gnu_result = maybe_implicit_deref (gnu_result);
        gnu_result = maybe_unconstrained_array (gnu_result);
        gnu_type = TREE_TYPE (gnu_result);
        if (Do_Range_Check (gnat_range_node))
          {
            /* Get the bounds of the slice.  */
            tree gnu_index_type
              = TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_result_type));
            tree gnu_min_expr = TYPE_MIN_VALUE (gnu_index_type);
            tree gnu_max_expr = TYPE_MAX_VALUE (gnu_index_type);
            /* Get the permitted bounds.  */
            tree gnu_base_index_type
              = TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type));
            tree gnu_base_min_expr = TYPE_MIN_VALUE (gnu_base_index_type);
            tree gnu_base_max_expr = TYPE_MAX_VALUE (gnu_base_index_type);
            tree gnu_expr_l, gnu_expr_h, gnu_expr_type;

            /* Check to see that the minimum slice value is in range.  */
            gnu_expr_l = emit_index_check (gnu_result,
                                           gnu_min_expr,
                                           gnu_base_min_expr,
                                           gnu_base_max_expr);

            /* Check to see that the maximum slice value is in range.  */
            gnu_expr_h = emit_index_check (gnu_result,
                                           gnu_max_expr,
                                           gnu_base_min_expr,
                                           gnu_base_max_expr);

            /* Derive a good type to convert everything to.  */
            gnu_expr_type = get_base_type (TREE_TYPE (gnu_expr_l));

            /* Build a compound expression that does the range checks and
               returns the low bound.  */
            gnu_expr = build_binary_op (COMPOUND_EXPR, gnu_expr_type,
                                        convert (gnu_expr_type, gnu_expr_h),
                                        convert (gnu_expr_type, gnu_expr_l));

           /* Build a conditional expression that does the range check and
              returns the low bound if the slice is not empty (max >= min),
              and returns the naked low bound otherwise (max < min), unless
              it is non-constant and the high bound is; this prevents VRP
              from inferring bogus ranges on the unlikely path.  */
            gnu_expr = fold_build3 (COND_EXPR, gnu_expr_type,
                                    build_binary_op (GE_EXPR, gnu_expr_type,
                                                     convert (gnu_expr_type,
                                                              gnu_max_expr),
                                                     convert (gnu_expr_type,
                                                              gnu_min_expr)),
                                    gnu_expr,
                                    TREE_CODE (gnu_min_expr) != INTEGER_CST
                                    && TREE_CODE (gnu_max_expr) == INTEGER_CST
                                    ? gnu_max_expr : gnu_min_expr);
          }
        else
          /* Simply return the naked low bound.  */
          gnu_expr = TYPE_MIN_VALUE (TYPE_DOMAIN (gnu_result_type));

        gnu_result = build_binary_op (ARRAY_RANGE_REF, gnu_result_type,
                                      gnu_result, gnu_expr);
      }
      break;

    case N_Selected_Component:
      {
        tree gnu_prefix = gnat_to_gnu (Prefix (gnat_node));
        Entity_Id gnat_field = Entity (Selector_Name (gnat_node));
        Entity_Id gnat_pref_type = Etype (Prefix (gnat_node));
        tree gnu_field;

        while (IN (Ekind (gnat_pref_type), Incomplete_Or_Private_Kind)
               || IN (Ekind (gnat_pref_type), Access_Kind))
          {
            if (IN (Ekind (gnat_pref_type), Incomplete_Or_Private_Kind))
              gnat_pref_type = Underlying_Type (gnat_pref_type);
            else if (IN (Ekind (gnat_pref_type), Access_Kind))
              gnat_pref_type = Designated_Type (gnat_pref_type);
          }

        gnu_prefix = maybe_implicit_deref (gnu_prefix);

        /* For discriminant references in tagged types always substitute the
           corresponding discriminant as the actual selected component. */

        if (Is_Tagged_Type (gnat_pref_type))
          while (Present (Corresponding_Discriminant (gnat_field)))
            gnat_field = Corresponding_Discriminant (gnat_field);

        /* For discriminant references of untagged types always substitute the
           corresponding stored discriminant. */

        else if (Present (Corresponding_Discriminant (gnat_field)))
          gnat_field = Original_Record_Component (gnat_field);

        /* Handle extracting the real or imaginary part of a complex.
           The real part is the first field and the imaginary the last.  */

        if (TREE_CODE (TREE_TYPE (gnu_prefix)) == COMPLEX_TYPE)
          gnu_result = build_unary_op (Present (Next_Entity (gnat_field))
                                       ? REALPART_EXPR : IMAGPART_EXPR,
                                       NULL_TREE, gnu_prefix);
        else
          {
            gnu_field = gnat_to_gnu_field_decl (gnat_field);

            /* If there are discriminants, the prefix might be
               evaluated more than once, which is a problem if it has
               side-effects. */
            if (Has_Discriminants (Is_Access_Type (Etype (Prefix (gnat_node)))
                                   ? Designated_Type (Etype
                                                      (Prefix (gnat_node)))
                                   : Etype (Prefix (gnat_node))))
              gnu_prefix = gnat_stabilize_reference (gnu_prefix, false);

            gnu_result
              = build_component_ref (gnu_prefix, NULL_TREE, gnu_field,
                                     (Nkind (Parent (gnat_node))
                                      == N_Attribute_Reference));
          }

        gcc_assert (gnu_result);
        gnu_result_type = get_unpadded_type (Etype (gnat_node));
      }
      break;

    case N_Attribute_Reference:
      {
        /* The attribute designator (like an enumeration value). */
        int attribute = Get_Attribute_Id (Attribute_Name (gnat_node));

        /* The Elab_Spec and Elab_Body attributes are special in that
           Prefix is a unit, not an object with a GCC equivalent.  Similarly
           for Elaborated, since that variable isn't otherwise known.  */
        if (attribute == Attr_Elab_Body || attribute == Attr_Elab_Spec)
          return (create_subprog_decl
                  (create_concat_name (Entity (Prefix (gnat_node)),
                                       attribute == Attr_Elab_Body
                                       ? "elabb" : "elabs"),
                   NULL_TREE, void_ftype, NULL_TREE, false, true, true, NULL,
                   gnat_node));

        gnu_result = Attribute_to_gnu (gnat_node, &gnu_result_type, attribute);
      }
      break;

    case N_Reference:
      /* Like 'Access as far as we are concerned.  */
      gnu_result = gnat_to_gnu (Prefix (gnat_node));
      gnu_result = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_result);
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      break;

    case N_Aggregate:
    case N_Extension_Aggregate:
      {
        tree gnu_aggr_type;

        /* ??? It is wrong to evaluate the type now, but there doesn't
           seem to be any other practical way of doing it.  */

        gcc_assert (!Expansion_Delayed (gnat_node));

        gnu_aggr_type = gnu_result_type
          = get_unpadded_type (Etype (gnat_node));

        if (TREE_CODE (gnu_result_type) == RECORD_TYPE
            && TYPE_CONTAINS_TEMPLATE_P (gnu_result_type))
          gnu_aggr_type
            = TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (gnu_result_type)));

        if (Null_Record_Present (gnat_node))
          gnu_result = gnat_build_constructor (gnu_aggr_type, NULL_TREE);

        else if (TREE_CODE (gnu_aggr_type) == RECORD_TYPE
                 || TREE_CODE (gnu_aggr_type) == UNION_TYPE)
          gnu_result
            = assoc_to_constructor (Etype (gnat_node),
                                    First (Component_Associations (gnat_node)),
                                    gnu_aggr_type);
        else if (TREE_CODE (gnu_aggr_type) == ARRAY_TYPE)
          gnu_result = pos_to_constructor (First (Expressions (gnat_node)),
                                           gnu_aggr_type,
                                           Component_Type (Etype (gnat_node)));
        else if (TREE_CODE (gnu_aggr_type) == COMPLEX_TYPE)
          gnu_result
            = build_binary_op
              (COMPLEX_EXPR, gnu_aggr_type,
               gnat_to_gnu (Expression (First
                                        (Component_Associations (gnat_node)))),
               gnat_to_gnu (Expression
                            (Next
                             (First (Component_Associations (gnat_node))))));
        else
          gcc_unreachable ();

        gnu_result = convert (gnu_result_type, gnu_result);
      }
      break;

    case N_Null:
      if (TARGET_VTABLE_USES_DESCRIPTORS
          && Ekind (Etype (gnat_node)) == E_Access_Subprogram_Type
          && Is_Dispatch_Table_Entity (Etype (gnat_node)))
        gnu_result = null_fdesc_node;
      else
        gnu_result = null_pointer_node;
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      break;

    case N_Type_Conversion:
    case N_Qualified_Expression:
      /* Get the operand expression.  */
      gnu_result = gnat_to_gnu (Expression (gnat_node));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));

      gnu_result
        = convert_with_check (Etype (gnat_node), gnu_result,
                              Do_Overflow_Check (gnat_node),
                              Do_Range_Check (Expression (gnat_node)),
                              Nkind (gnat_node) == N_Type_Conversion
                              && Float_Truncate (gnat_node));
      break;

    case N_Unchecked_Type_Conversion:
      gnu_result = gnat_to_gnu (Expression (gnat_node));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));

      /* If the result is a pointer type, see if we are improperly
         converting to a stricter alignment.  */
      if (STRICT_ALIGNMENT && POINTER_TYPE_P (gnu_result_type)
          && IN (Ekind (Etype (gnat_node)), Access_Kind))
        {
          unsigned int align = known_alignment (gnu_result);
          tree gnu_obj_type = TREE_TYPE (gnu_result_type);
          unsigned int oalign = TYPE_ALIGN (gnu_obj_type);

          if (align != 0 && align < oalign && !TYPE_ALIGN_OK (gnu_obj_type))
            post_error_ne_tree_2
              ("?source alignment (^) '< alignment of & (^)",
               gnat_node, Designated_Type (Etype (gnat_node)),
               size_int (align / BITS_PER_UNIT), oalign / BITS_PER_UNIT);
        }

      /* If we are converting a descriptor to a function pointer, first
         build the pointer.  */
      if (TARGET_VTABLE_USES_DESCRIPTORS
          && TREE_TYPE (gnu_result) == fdesc_type_node
          && POINTER_TYPE_P (gnu_result_type))
        gnu_result = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_result);

      gnu_result = unchecked_convert (gnu_result_type, gnu_result,
                                      No_Truncation (gnat_node));
      break;

    case N_In:
    case N_Not_In:
      {
        tree gnu_object = gnat_to_gnu (Left_Opnd (gnat_node));
        Node_Id gnat_range = Right_Opnd (gnat_node);
        tree gnu_low;
        tree gnu_high;

        /* GNAT_RANGE is either an N_Range node or an identifier
           denoting a subtype.  */
        if (Nkind (gnat_range) == N_Range)
          {
            gnu_low = gnat_to_gnu (Low_Bound (gnat_range));
            gnu_high = gnat_to_gnu (High_Bound (gnat_range));
          }
        else if (Nkind (gnat_range) == N_Identifier
              || Nkind (gnat_range) == N_Expanded_Name)
          {
            tree gnu_range_type = get_unpadded_type (Entity (gnat_range));

            gnu_low = TYPE_MIN_VALUE (gnu_range_type);
            gnu_high = TYPE_MAX_VALUE (gnu_range_type);
          }
        else
          gcc_unreachable ();

        gnu_result_type = get_unpadded_type (Etype (gnat_node));

        /* If LOW and HIGH are identical, perform an equality test.
           Otherwise, ensure that GNU_OBJECT is only evaluated once
           and perform a full range test.  */
        if (operand_equal_p (gnu_low, gnu_high, 0))
          gnu_result = build_binary_op (EQ_EXPR, gnu_result_type,
                                        gnu_object, gnu_low);
        else
          {
            gnu_object = protect_multiple_eval (gnu_object);
            gnu_result
              = build_binary_op (TRUTH_ANDIF_EXPR, gnu_result_type,
                                 build_binary_op (GE_EXPR, gnu_result_type,
                                                  gnu_object, gnu_low),
                                 build_binary_op (LE_EXPR, gnu_result_type,
                                                  gnu_object, gnu_high));
          }

        if (Nkind (gnat_node) == N_Not_In)
          gnu_result = invert_truthvalue (gnu_result);
      }
      break;

    case N_Op_Divide:
      gnu_lhs = gnat_to_gnu (Left_Opnd (gnat_node));
      gnu_rhs = gnat_to_gnu (Right_Opnd (gnat_node));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result = build_binary_op (FLOAT_TYPE_P (gnu_result_type)
                                    ? RDIV_EXPR
                                    : (Rounded_Result (gnat_node)
                                       ? ROUND_DIV_EXPR : TRUNC_DIV_EXPR),
                                    gnu_result_type, gnu_lhs, gnu_rhs);
      break;

    case N_Op_Or:    case N_Op_And:      case N_Op_Xor:
      /* These can either be operations on booleans or on modular types.
         Fall through for boolean types since that's the way GNU_CODES is
         set up.  */
      if (IN (Ekind (Underlying_Type (Etype (gnat_node))),
              Modular_Integer_Kind))
        {
          enum tree_code code
            = (Nkind (gnat_node) == N_Op_Or ? BIT_IOR_EXPR
               : Nkind (gnat_node) == N_Op_And ? BIT_AND_EXPR
               : BIT_XOR_EXPR);

          gnu_lhs = gnat_to_gnu (Left_Opnd (gnat_node));
          gnu_rhs = gnat_to_gnu (Right_Opnd (gnat_node));
          gnu_result_type = get_unpadded_type (Etype (gnat_node));
          gnu_result = build_binary_op (code, gnu_result_type,
                                        gnu_lhs, gnu_rhs);
          break;
        }

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

    case N_Op_Eq:    case N_Op_Ne:       case N_Op_Lt:
    case N_Op_Le:    case N_Op_Gt:       case N_Op_Ge:
    case N_Op_Add:   case N_Op_Subtract: case N_Op_Multiply:
    case N_Op_Mod:   case N_Op_Rem:
    case N_Op_Rotate_Left:
    case N_Op_Rotate_Right:
    case N_Op_Shift_Left:
    case N_Op_Shift_Right:
    case N_Op_Shift_Right_Arithmetic:
    case N_And_Then: case N_Or_Else:
      {
        enum tree_code code = gnu_codes[Nkind (gnat_node)];
        bool ignore_lhs_overflow = false;
        tree gnu_type;

        gnu_lhs = gnat_to_gnu (Left_Opnd (gnat_node));
        gnu_rhs = gnat_to_gnu (Right_Opnd (gnat_node));
        gnu_type = gnu_result_type = get_unpadded_type (Etype (gnat_node));

        /* If this is a comparison operator, convert any references to
           an unconstrained array value into a reference to the
           actual array.  */
        if (TREE_CODE_CLASS (code) == tcc_comparison)
          {
            gnu_lhs = maybe_unconstrained_array (gnu_lhs);
            gnu_rhs = maybe_unconstrained_array (gnu_rhs);
          }

        /* If the result type is a private type, its full view may be a
           numeric subtype. The representation we need is that of its base
           type, given that it is the result of an arithmetic operation.  */
        else if (Is_Private_Type (Etype (gnat_node)))
          gnu_type = gnu_result_type
            = get_unpadded_type (Base_Type (Full_View (Etype (gnat_node))));

        /* If this is a shift whose count is not guaranteed to be correct,
           we need to adjust the shift count.  */
        if (IN (Nkind (gnat_node), N_Op_Shift)
            && !Shift_Count_OK (gnat_node))
          {
            tree gnu_count_type = get_base_type (TREE_TYPE (gnu_rhs));
            tree gnu_max_shift
              = convert (gnu_count_type, TYPE_SIZE (gnu_type));

            if (Nkind (gnat_node) == N_Op_Rotate_Left
                || Nkind (gnat_node) == N_Op_Rotate_Right)
              gnu_rhs = build_binary_op (TRUNC_MOD_EXPR, gnu_count_type,
                                         gnu_rhs, gnu_max_shift);
            else if (Nkind (gnat_node) == N_Op_Shift_Right_Arithmetic)
              gnu_rhs
                = build_binary_op
                  (MIN_EXPR, gnu_count_type,
                   build_binary_op (MINUS_EXPR,
                                    gnu_count_type,
                                    gnu_max_shift,
                                    convert (gnu_count_type,
                                             integer_one_node)),
                   gnu_rhs);
          }

        /* For right shifts, the type says what kind of shift to do,
           so we may need to choose a different type.  In this case,
           we have to ignore integer overflow lest it propagates all
           the way down and causes a CE to be explicitly raised.  */
        if (Nkind (gnat_node) == N_Op_Shift_Right
            && !TYPE_UNSIGNED (gnu_type))
          {
            gnu_type = gnat_unsigned_type (gnu_type);
            ignore_lhs_overflow = true;
          }
        else if (Nkind (gnat_node) == N_Op_Shift_Right_Arithmetic
                 && TYPE_UNSIGNED (gnu_type))
          {
            gnu_type = gnat_signed_type (gnu_type);
            ignore_lhs_overflow = true;
          }

        if (gnu_type != gnu_result_type)
          {
            tree gnu_old_lhs = gnu_lhs;
            gnu_lhs = convert (gnu_type, gnu_lhs);
            if (TREE_CODE (gnu_lhs) == INTEGER_CST && ignore_lhs_overflow)
              TREE_OVERFLOW (gnu_lhs) = TREE_OVERFLOW (gnu_old_lhs);
            gnu_rhs = convert (gnu_type, gnu_rhs);
          }

        gnu_result = build_binary_op (code, gnu_type, gnu_lhs, gnu_rhs);

        /* If this is a logical shift with the shift count not verified,
           we must return zero if it is too large.  We cannot compensate
           above in this case.  */
        if ((Nkind (gnat_node) == N_Op_Shift_Left
             || Nkind (gnat_node) == N_Op_Shift_Right)
            && !Shift_Count_OK (gnat_node))
          gnu_result
            = build_cond_expr
              (gnu_type,
               build_binary_op (GE_EXPR, integer_type_node,
                                gnu_rhs,
                                convert (TREE_TYPE (gnu_rhs),
                                         TYPE_SIZE (gnu_type))),
               convert (gnu_type, integer_zero_node),
               gnu_result);
      }
      break;

    case N_Conditional_Expression:
      {
        tree gnu_cond = gnat_to_gnu (First (Expressions (gnat_node)));
        tree gnu_true = gnat_to_gnu (Next (First (Expressions (gnat_node))));
        tree gnu_false
          = gnat_to_gnu (Next (Next (First (Expressions (gnat_node)))));

        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        gnu_result = build_cond_expr (gnu_result_type,
                                      gnat_truthvalue_conversion (gnu_cond),
                                      gnu_true, gnu_false);
      }
      break;

    case N_Op_Plus:
      gnu_result = gnat_to_gnu (Right_Opnd (gnat_node));
      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      break;

    case N_Op_Not:
      /* This case can apply to a boolean or a modular type.
         Fall through for a boolean operand since GNU_CODES is set
         up to handle this.  */
      if (Is_Modular_Integer_Type (Etype (gnat_node))
          || (Ekind (Etype (gnat_node)) == E_Private_Type
              && Is_Modular_Integer_Type (Full_View (Etype (gnat_node)))))
        {
          gnu_expr = gnat_to_gnu (Right_Opnd (gnat_node));
          gnu_result_type = get_unpadded_type (Etype (gnat_node));
          gnu_result = build_unary_op (BIT_NOT_EXPR, gnu_result_type,
                                       gnu_expr);
          break;
        }

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

    case N_Op_Minus:  case N_Op_Abs:
      gnu_expr = gnat_to_gnu (Right_Opnd (gnat_node));

      if (Ekind (Etype (gnat_node)) != E_Private_Type)
         gnu_result_type = get_unpadded_type (Etype (gnat_node));
      else
         gnu_result_type = get_unpadded_type (Base_Type
                                              (Full_View (Etype (gnat_node))));

      gnu_result = build_unary_op (gnu_codes[Nkind (gnat_node)],
                                   gnu_result_type, gnu_expr);
      break;

    case N_Allocator:
      {
        tree gnu_init = 0;
        tree gnu_type;
        bool ignore_init_type = false;

        gnat_temp = Expression (gnat_node);

        /* The Expression operand can either be an N_Identifier or
           Expanded_Name, which must represent a type, or a
           N_Qualified_Expression, which contains both the object type and an
           initial value for the object.  */
        if (Nkind (gnat_temp) == N_Identifier
            || Nkind (gnat_temp) == N_Expanded_Name)
          gnu_type = gnat_to_gnu_type (Entity (gnat_temp));
        else if (Nkind (gnat_temp) == N_Qualified_Expression)
          {
            Entity_Id gnat_desig_type
              = Designated_Type (Underlying_Type (Etype (gnat_node)));

            ignore_init_type = Has_Constrained_Partial_View (gnat_desig_type);
            gnu_init = gnat_to_gnu (Expression (gnat_temp));

            gnu_init = maybe_unconstrained_array (gnu_init);
            if (Do_Range_Check (Expression (gnat_temp)))
              gnu_init = emit_range_check (gnu_init, gnat_desig_type);

            if (Is_Elementary_Type (gnat_desig_type)
                || Is_Constrained (gnat_desig_type))
              {
                gnu_type = gnat_to_gnu_type (gnat_desig_type);
                gnu_init = convert (gnu_type, gnu_init);
              }
            else
              {
                gnu_type = gnat_to_gnu_type (Etype (Expression (gnat_temp)));
                if (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE)
                  gnu_type = TREE_TYPE (gnu_init);

                gnu_init = convert (gnu_type, gnu_init);
              }
          }
        else
          gcc_unreachable ();

        gnu_result_type = get_unpadded_type (Etype (gnat_node));
        return build_allocator (gnu_type, gnu_init, gnu_result_type,
                                Procedure_To_Call (gnat_node),
                                Storage_Pool (gnat_node), gnat_node,
                                ignore_init_type);
      }
      break;

    /***************************/
    /* Chapter 5: Statements:  */
    /***************************/

    case N_Label:
      gnu_result = build1 (LABEL_EXPR, void_type_node,
                           gnat_to_gnu (Identifier (gnat_node)));
      break;

    case N_Null_Statement:
      gnu_result = alloc_stmt_list ();
      break;

    case N_Assignment_Statement:
      /* Get the LHS and RHS of the statement and convert any reference to an
         unconstrained array into a reference to the underlying array.
         If we are not to do range checking and the RHS is an N_Function_Call,
         pass the LHS to the call function.  */
      gnu_lhs = maybe_unconstrained_array (gnat_to_gnu (Name (gnat_node)));

      /* If the type has a size that overflows, convert this into raise of
         Storage_Error: execution shouldn't have gotten here anyway.  */
      if (TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (gnu_lhs))) == INTEGER_CST
           && TREE_OVERFLOW (TYPE_SIZE_UNIT (TREE_TYPE (gnu_lhs))))
        gnu_result = build_call_raise (SE_Object_Too_Large, gnat_node,
                                       N_Raise_Storage_Error);
      else if (Nkind (Expression (gnat_node)) == N_Function_Call
               && !Do_Range_Check (Expression (gnat_node)))
        gnu_result = call_to_gnu (Expression (gnat_node),
                                  &gnu_result_type, gnu_lhs);
      else
        {
          gnu_rhs
            = maybe_unconstrained_array (gnat_to_gnu (Expression (gnat_node)));

          /* If range check is needed, emit code to generate it */
          if (Do_Range_Check (Expression (gnat_node)))
            gnu_rhs = emit_range_check (gnu_rhs, Etype (Name (gnat_node)));

          gnu_result
            = build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_lhs, gnu_rhs);
        }
      break;

    case N_If_Statement:
      {
        tree *gnu_else_ptr;     /* Point to put next "else if" or "else". */

        /* Make the outer COND_EXPR.  Avoid non-determinism.  */
        gnu_result = build3 (COND_EXPR, void_type_node,
                             gnat_to_gnu (Condition (gnat_node)),
                             NULL_TREE, NULL_TREE);
        COND_EXPR_THEN (gnu_result)
          = build_stmt_group (Then_Statements (gnat_node), false);
        TREE_SIDE_EFFECTS (gnu_result) = 1;
        gnu_else_ptr = &COND_EXPR_ELSE (gnu_result);

        /* Now make a COND_EXPR for each of the "else if" parts.  Put each
           into the previous "else" part and point to where to put any
           outer "else".  Also avoid non-determinism.  */
        if (Present (Elsif_Parts (gnat_node)))
          for (gnat_temp = First (Elsif_Parts (gnat_node));
               Present (gnat_temp); gnat_temp = Next (gnat_temp))
            {
              gnu_expr = build3 (COND_EXPR, void_type_node,
                                 gnat_to_gnu (Condition (gnat_temp)),
                                 NULL_TREE, NULL_TREE);
              COND_EXPR_THEN (gnu_expr)
                = build_stmt_group (Then_Statements (gnat_temp), false);
              TREE_SIDE_EFFECTS (gnu_expr) = 1;
              set_expr_location_from_node (gnu_expr, gnat_temp);
              *gnu_else_ptr = gnu_expr;
              gnu_else_ptr = &COND_EXPR_ELSE (gnu_expr);
            }

        *gnu_else_ptr = build_stmt_group (Else_Statements (gnat_node), false);
      }
      break;

    case N_Case_Statement:
      gnu_result = Case_Statement_to_gnu (gnat_node);
      break;

    case N_Loop_Statement:
      gnu_result = Loop_Statement_to_gnu (gnat_node);
      break;

    case N_Block_Statement:
      start_stmt_group ();
      gnat_pushlevel ();
      process_decls (Declarations (gnat_node), Empty, Empty, true, true);
      add_stmt (gnat_to_gnu (Handled_Statement_Sequence (gnat_node)));
      gnat_poplevel ();
      gnu_result = end_stmt_group ();

      if (Present (Identifier (gnat_node)))
        mark_out_of_scope (Entity (Identifier (gnat_node)));
      break;

    case N_Exit_Statement:
      gnu_result
        = build2 (EXIT_STMT, void_type_node,
                  (Present (Condition (gnat_node))
                   ? gnat_to_gnu (Condition (gnat_node)) : NULL_TREE),
                  (Present (Name (gnat_node))
                   ? get_gnu_tree (Entity (Name (gnat_node)))
                   : TREE_VALUE (gnu_loop_label_stack)));
      break;

    case N_Return_Statement:
      {
        /* The gnu function type of the subprogram currently processed.  */
        tree gnu_subprog_type = TREE_TYPE (current_function_decl);
        /* The return value from the subprogram.  */
        tree gnu_ret_val = NULL_TREE;
        /* The place to put the return value.  */
        tree gnu_lhs;

        /* If we are dealing with a "return;" from an Ada procedure with
           parameters passed by copy in copy out, we need to return a record
           containing the final values of these parameters.  If the list
           contains only one entry, return just that entry.

           For a full description of the copy in copy out parameter mechanism,
           see the part of the gnat_to_gnu_entity routine dealing with the
           translation of subprograms.

           But if we have a return label defined, convert this into
           a branch to that label.  */

        if (TREE_VALUE (gnu_return_label_stack))
          {
            gnu_result = build1 (GOTO_EXPR, void_type_node,
                                 TREE_VALUE (gnu_return_label_stack));
            break;
          }

        else if (TYPE_CI_CO_LIST (gnu_subprog_type))
          {
            gnu_lhs = DECL_RESULT (current_function_decl);
            if (list_length (TYPE_CI_CO_LIST (gnu_subprog_type)) == 1)
              gnu_ret_val = TREE_VALUE (TYPE_CI_CO_LIST (gnu_subprog_type));
            else
              gnu_ret_val
                = gnat_build_constructor (TREE_TYPE (gnu_subprog_type),
                                          TYPE_CI_CO_LIST (gnu_subprog_type));
          }

        /* If the Ada subprogram is a function, we just need to return the
           expression.   If the subprogram returns an unconstrained
           array, we have to allocate a new version of the result and
           return it.  If we return by reference, return a pointer.  */

        else if (Present (Expression (gnat_node)))
          {
            /* If the current function returns by target pointer and we
               are doing a call, pass that target to the call.  */
            if (TYPE_RETURNS_BY_TARGET_PTR_P (gnu_subprog_type)
                && Nkind (Expression (gnat_node)) == N_Function_Call)
              {
                gnu_lhs
                  = build_unary_op (INDIRECT_REF, NULL_TREE,
                                    DECL_ARGUMENTS (current_function_decl));
                gnu_result = call_to_gnu (Expression (gnat_node),
                                          &gnu_result_type, gnu_lhs);
              }
            else
              {
                gnu_ret_val = gnat_to_gnu (Expression (gnat_node));

                if (TYPE_RETURNS_BY_TARGET_PTR_P (gnu_subprog_type))
                  /* The original return type was unconstrained so dereference
                     the TARGET pointer in the actual return value's type. */
                  gnu_lhs
                    = build_unary_op (INDIRECT_REF, TREE_TYPE (gnu_ret_val),
                                      DECL_ARGUMENTS (current_function_decl));
                else
                  gnu_lhs = DECL_RESULT (current_function_decl);

                /* Do not remove the padding from GNU_RET_VAL if the inner
                   type is self-referential since we want to allocate the fixed
                   size in that case.  */
                if (TREE_CODE (gnu_ret_val) == COMPONENT_REF
                    && (TREE_CODE (TREE_TYPE (TREE_OPERAND (gnu_ret_val, 0)))
                        == RECORD_TYPE)
                    && (TYPE_IS_PADDING_P
                        (TREE_TYPE (TREE_OPERAND (gnu_ret_val, 0))))
                    && (CONTAINS_PLACEHOLDER_P
                        (TYPE_SIZE (TREE_TYPE (gnu_ret_val)))))
                  gnu_ret_val = TREE_OPERAND (gnu_ret_val, 0);

                if (TYPE_RETURNS_BY_REF_P (gnu_subprog_type)
                    || By_Ref (gnat_node))
                  gnu_ret_val
                    = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_ret_val);

                else if (TYPE_RETURNS_UNCONSTRAINED_P (gnu_subprog_type))
                  {
                    gnu_ret_val = maybe_unconstrained_array (gnu_ret_val);
                    gnu_ret_val
                      = build_allocator (TREE_TYPE (gnu_ret_val),
                                         gnu_ret_val,
                                         TREE_TYPE (gnu_subprog_type),
                                         Procedure_To_Call (gnat_node),
                                         Storage_Pool (gnat_node),
                                         gnat_node, false);
                  }
              }
          }
        else
          /* If the Ada subprogram is a regular procedure, just return.  */
          gnu_lhs = NULL_TREE;

        if (TYPE_RETURNS_BY_TARGET_PTR_P (gnu_subprog_type))
          {
            if (gnu_ret_val)
              gnu_result = build_binary_op (MODIFY_EXPR, NULL_TREE,
                                            gnu_lhs, gnu_ret_val);
            add_stmt_with_node (gnu_result, gnat_node);
            gnu_lhs = NULL_TREE;
          }

        gnu_result = build_return_expr (gnu_lhs, gnu_ret_val);
      }
      break;

    case N_Goto_Statement:
      gnu_result = build1 (GOTO_EXPR, void_type_node,
                           gnat_to_gnu (Name (gnat_node)));
      break;

    /****************************/
    /* Chapter 6: Subprograms:  */
    /****************************/

    case N_Subprogram_Declaration:
      /* Unless there is a freeze node, declare the subprogram.  We consider
         this a "definition" even though we're not generating code for
         the subprogram because we will be making the corresponding GCC
         node here. */

      if (No (Freeze_Node (Defining_Entity (Specification (gnat_node)))))
        gnat_to_gnu_entity (Defining_Entity (Specification (gnat_node)),
                            NULL_TREE, 1);
      gnu_result = alloc_stmt_list ();
      break;

    case N_Abstract_Subprogram_Declaration:
      /* This subprogram doesn't exist for code generation purposes, but we
         have to elaborate the types of any parameters and result, unless
         they are imported types (nothing to generate in this case).  */

      /* Process the parameter types first.  */

      for (gnat_temp
           = First_Formal_With_Extras
              (Defining_Entity (Specification (gnat_node)));
           Present (gnat_temp);
           gnat_temp = Next_Formal_With_Extras (gnat_temp))
        if (Is_Itype (Etype (gnat_temp))
            && !From_With_Type (Etype (gnat_temp)))
          gnat_to_gnu_entity (Etype (gnat_temp), NULL_TREE, 0);


      /* Then the result type, set to Standard_Void_Type for procedures.  */

      {
        Entity_Id gnat_temp_type
          = Etype (Defining_Entity (Specification (gnat_node)));

        if (Is_Itype (gnat_temp_type) && !From_With_Type (gnat_temp_type))
          gnat_to_gnu_entity (Etype (gnat_temp_type), NULL_TREE, 0);
      }

      gnu_result = alloc_stmt_list ();
      break;

    case N_Defining_Program_Unit_Name:
      /* For a child unit identifier go up a level to get the
         specification.  We get this when we try to find the spec of
         a child unit package that is the compilation unit being compiled. */
      gnu_result = gnat_to_gnu (Parent (gnat_node));
      break;

    case N_Subprogram_Body:
      Subprogram_Body_to_gnu (gnat_node);
      gnu_result = alloc_stmt_list ();
      break;

    case N_Function_Call:
    case N_Procedure_Call_Statement:
      gnu_result = call_to_gnu (gnat_node, &gnu_result_type, NULL_TREE);
      break;

    /*************************/
    /* Chapter 7: Packages:  */
    /*************************/

    case N_Package_Declaration:
      gnu_result = gnat_to_gnu (Specification (gnat_node));
      break;

    case N_Package_Specification:

      start_stmt_group ();
      process_decls (Visible_Declarations (gnat_node),
                     Private_Declarations (gnat_node), Empty, true, true);
      gnu_result = end_stmt_group ();
      break;

    case N_Package_Body:

      /* If this is the body of a generic package - do nothing */
      if (Ekind (Corresponding_Spec (gnat_node)) == E_Generic_Package)
        {
          gnu_result = alloc_stmt_list ();
          break;
        }

      start_stmt_group ();
      process_decls (Declarations (gnat_node), Empty, Empty, true, true);

      if (Present (Handled_Statement_Sequence (gnat_node)))
        add_stmt (gnat_to_gnu (Handled_Statement_Sequence (gnat_node)));

      gnu_result = end_stmt_group ();
      break;

    /*********************************/
    /* Chapter 8: Visibility Rules:  */
    /*********************************/

    case N_Use_Package_Clause:
    case N_Use_Type_Clause:
      /* Nothing to do here - but these may appear in list of declarations */
      gnu_result = alloc_stmt_list ();
      break;

    /***********************/
    /* Chapter 9: Tasks:   */
    /***********************/

    case N_Protected_Type_Declaration:
      gnu_result = alloc_stmt_list ();
      break;

    case N_Single_Task_Declaration:
      gnat_to_gnu_entity (Defining_Entity (gnat_node), NULL_TREE, 1);
      gnu_result = alloc_stmt_list ();
      break;

    /***********************************************************/
    /* Chapter 10: Program Structure and Compilation Issues:   */
    /***********************************************************/

    case N_Compilation_Unit:

      /* This is not called for the main unit, which is handled in function
         gigi above.  */
      start_stmt_group ();
      gnat_pushlevel ();

      Compilation_Unit_to_gnu (gnat_node);
      gnu_result = alloc_stmt_list ();
      break;

    case N_Subprogram_Body_Stub:
    case N_Package_Body_Stub:
    case N_Protected_Body_Stub:
    case N_Task_Body_Stub:
      /* Simply process whatever unit is being inserted.  */
      gnu_result = gnat_to_gnu (Unit (Library_Unit (gnat_node)));
      break;

    case N_Subunit:
      gnu_result = gnat_to_gnu (Proper_Body (gnat_node));
      break;

    /***************************/
    /* Chapter 11: Exceptions: */
    /***************************/

    case N_Handled_Sequence_Of_Statements:
      /* If there is an At_End procedure attached to this node, and the EH
         mechanism is SJLJ, we must have at least a corresponding At_End
         handler, unless the No_Exception_Handlers restriction is set.  */
      gcc_assert (type_annotate_only
                  || Exception_Mechanism != Setjmp_Longjmp
                  || No (At_End_Proc (gnat_node))
                  || Present (Exception_Handlers (gnat_node))
                  || No_Exception_Handlers_Set ());

      gnu_result = Handled_Sequence_Of_Statements_to_gnu (gnat_node);
      break;

    case N_Exception_Handler:
      if (Exception_Mechanism == Setjmp_Longjmp)
        gnu_result = Exception_Handler_to_gnu_sjlj (gnat_node);
      else if (Exception_Mechanism == Back_End_Exceptions)
        gnu_result = Exception_Handler_to_gnu_zcx (gnat_node);
      else
        gcc_unreachable ();

      break;

    case N_Push_Constraint_Error_Label:
      push_exception_label_stack (&gnu_constraint_error_label_stack,
                                  Exception_Label (gnat_node));
      break;

    case N_Push_Storage_Error_Label:
      push_exception_label_stack (&gnu_storage_error_label_stack,
                                  Exception_Label (gnat_node));
      break;

    case N_Push_Program_Error_Label:
      push_exception_label_stack (&gnu_program_error_label_stack,
                                  Exception_Label (gnat_node));
      break;

    case N_Pop_Constraint_Error_Label:
      gnu_constraint_error_label_stack
        = TREE_CHAIN (gnu_constraint_error_label_stack);
      break;

    case N_Pop_Storage_Error_Label:
      gnu_storage_error_label_stack
        = TREE_CHAIN (gnu_storage_error_label_stack);
      break;

    case N_Pop_Program_Error_Label:
      gnu_program_error_label_stack
        = TREE_CHAIN (gnu_program_error_label_stack);
      break;

    /*******************************/
    /* Chapter 12: Generic Units:  */
    /*******************************/

    case N_Generic_Function_Renaming_Declaration:
    case N_Generic_Package_Renaming_Declaration:
    case N_Generic_Procedure_Renaming_Declaration:
    case N_Generic_Package_Declaration:
    case N_Generic_Subprogram_Declaration:
    case N_Package_Instantiation:
    case N_Procedure_Instantiation:
    case N_Function_Instantiation:
      /* These nodes can appear on a declaration list but there is nothing to
         to be done with them.  */
      gnu_result = alloc_stmt_list ();
      break;

    /***************************************************/
    /* Chapter 13: Representation Clauses and          */
    /*             Implementation-Dependent Features:  */
    /***************************************************/

    case N_Attribute_Definition_Clause:

      gnu_result = alloc_stmt_list ();

      /* The only one we need deal with is for 'Address.  For the others, SEM
         puts the information elsewhere.  We need only deal with 'Address
         if the object has a Freeze_Node (which it never will currently).  */
      if (Get_Attribute_Id (Chars (gnat_node)) != Attr_Address
          || No (Freeze_Node (Entity (Name (gnat_node)))))
        break;

      /* Get the value to use as the address and save it as the
         equivalent for GNAT_TEMP.  When the object is frozen,
         gnat_to_gnu_entity will do the right thing. */
      save_gnu_tree (Entity (Name (gnat_node)),
                     gnat_to_gnu (Expression (gnat_node)), true);
      break;

    case N_Enumeration_Representation_Clause:
    case N_Record_Representation_Clause:
    case N_At_Clause:
      /* We do nothing with these.  SEM puts the information elsewhere.  */
      gnu_result = alloc_stmt_list ();
      break;

    case N_Code_Statement:
      if (!type_annotate_only)
        {
          tree gnu_template = gnat_to_gnu (Asm_Template (gnat_node));
          tree gnu_inputs = NULL_TREE, gnu_outputs = NULL_TREE;
          tree gnu_clobbers = NULL_TREE, tail;
          bool allows_mem, allows_reg, fake;
          int ninputs, noutputs, i;
          const char **oconstraints;
          const char *constraint;
          char *clobber;

          /* First retrieve the 3 operand lists built by the front-end.  */
          Setup_Asm_Outputs (gnat_node);
          while (Present (gnat_temp = Asm_Output_Variable ()))
            {
              tree gnu_value = gnat_to_gnu (gnat_temp);
              tree gnu_constr = build_tree_list (NULL_TREE, gnat_to_gnu
                                                 (Asm_Output_Constraint ()));

              gnu_outputs = tree_cons (gnu_constr, gnu_value, gnu_outputs);
              Next_Asm_Output ();
            }

          Setup_Asm_Inputs (gnat_node);
          while (Present (gnat_temp = Asm_Input_Value ()))
            {
              tree gnu_value = gnat_to_gnu (gnat_temp);
              tree gnu_constr = build_tree_list (NULL_TREE, gnat_to_gnu
                                                 (Asm_Input_Constraint ()));

              gnu_inputs = tree_cons (gnu_constr, gnu_value, gnu_inputs);
              Next_Asm_Input ();
            }

          Clobber_Setup (gnat_node);
          while ((clobber = Clobber_Get_Next ()))
            gnu_clobbers
              = tree_cons (NULL_TREE,
                           build_string (strlen (clobber) + 1, clobber),
                           gnu_clobbers);

          /* Then perform some standard checking and processing on the
             operands.  In particular, mark them addressable if needed.  */
          gnu_outputs = nreverse (gnu_outputs);
          noutputs = list_length (gnu_outputs);
          gnu_inputs = nreverse (gnu_inputs);
          ninputs = list_length (gnu_inputs);
          oconstraints
            = (const char **) alloca (noutputs * sizeof (const char *));

          for (i = 0, tail = gnu_outputs; tail; ++i, tail = TREE_CHAIN (tail))
            {
              tree output = TREE_VALUE (tail);
              constraint
                = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));
              oconstraints[i] = constraint;

              if (parse_output_constraint (&constraint, i, ninputs, noutputs,
                                           &allows_mem, &allows_reg, &fake))
                {
                  /* If the operand is going to end up in memory,
                     mark it addressable.  Note that we don't test
                     allows_mem like in the input case below; this
                     is modelled on the C front-end.  */
                  if (!allows_reg
                      && !gnat_mark_addressable (output))
                    output = error_mark_node;
                }
              else
                output = error_mark_node;

              TREE_VALUE (tail) = output;
            }

          for (i = 0, tail = gnu_inputs; tail; ++i, tail = TREE_CHAIN (tail))
            {
              tree input = TREE_VALUE (tail);
              constraint
                = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tail)));

              if (parse_input_constraint (&constraint, i, ninputs, noutputs,
                                          0, oconstraints,
                                          &allows_mem, &allows_reg))
                {
                  /* If the operand is going to end up in memory,
                     mark it addressable.  */
                  if (!allows_reg && allows_mem
                      && !gnat_mark_addressable (input))
                    input = error_mark_node;
                }
              else
                input = error_mark_node;

              TREE_VALUE (tail) = input;
            }

          gnu_result = build4 (ASM_EXPR,  void_type_node,
                               gnu_template, gnu_outputs,
                               gnu_inputs, gnu_clobbers);
          ASM_VOLATILE_P (gnu_result) = Is_Asm_Volatile (gnat_node);
        }
      else
        gnu_result = alloc_stmt_list ();

      break;

    /***************************************************/
    /* Added Nodes                                     */
    /***************************************************/

    case N_Freeze_Entity:
      start_stmt_group ();
      process_freeze_entity (gnat_node);
      process_decls (Actions (gnat_node), Empty, Empty, true, true);
      gnu_result = end_stmt_group ();
      break;

    case N_Itype_Reference:
      if (!present_gnu_tree (Itype (gnat_node)))
        process_type (Itype (gnat_node));

      gnu_result = alloc_stmt_list ();
      break;

    case N_Free_Statement:
      if (!type_annotate_only)
        {
          tree gnu_ptr = gnat_to_gnu (Expression (gnat_node));
          tree gnu_ptr_type = TREE_TYPE (gnu_ptr);
          tree gnu_obj_type;
          tree gnu_actual_obj_type = 0;
          tree gnu_obj_size;
          unsigned int align;
          unsigned int default_allocator_alignment
            = get_target_default_allocator_alignment () * BITS_PER_UNIT;

          /* If this is a thin pointer, we must dereference it to create
             a fat pointer, then go back below to a thin pointer.  The
             reason for this is that we need a fat pointer someplace in
             order to properly compute the size.  */
          if (TYPE_THIN_POINTER_P (TREE_TYPE (gnu_ptr)))
            gnu_ptr = build_unary_op (ADDR_EXPR, NULL_TREE,
                                      build_unary_op (INDIRECT_REF, NULL_TREE,
                                                      gnu_ptr));

          /* If this is an unconstrained array, we know the object must
             have been allocated with the template in front of the object.
             So pass the template address, but get the total size.  Do this
             by converting to a thin pointer.  */
          if (TYPE_FAT_POINTER_P (TREE_TYPE (gnu_ptr)))
            gnu_ptr
              = convert (build_pointer_type
                         (TYPE_OBJECT_RECORD_TYPE
                          (TYPE_UNCONSTRAINED_ARRAY (TREE_TYPE (gnu_ptr)))),
                         gnu_ptr);

          gnu_obj_type = TREE_TYPE (TREE_TYPE (gnu_ptr));

          if (Present (Actual_Designated_Subtype (gnat_node)))
            {
              gnu_actual_obj_type
                = gnat_to_gnu_type (Actual_Designated_Subtype (gnat_node));

              if (TYPE_FAT_OR_THIN_POINTER_P (gnu_ptr_type))
                gnu_actual_obj_type
                  = build_unc_object_type_from_ptr (gnu_ptr_type,
                      gnu_actual_obj_type,
                      get_identifier ("DEALLOC"));
            }
          else
            gnu_actual_obj_type = gnu_obj_type;

          gnu_obj_size = TYPE_SIZE_UNIT (gnu_actual_obj_type);
          align = TYPE_ALIGN (gnu_obj_type);

          if (TREE_CODE (gnu_obj_type) == RECORD_TYPE
              && TYPE_CONTAINS_TEMPLATE_P (gnu_obj_type))
            {
              tree gnu_char_ptr_type = build_pointer_type (char_type_node);
              tree gnu_pos = byte_position (TYPE_FIELDS (gnu_obj_type));
              tree gnu_byte_offset
                = convert (sizetype,
                           size_diffop (size_zero_node, gnu_pos));
              gnu_byte_offset = fold_build1 (NEGATE_EXPR, sizetype, gnu_byte_offset);

              gnu_ptr = convert (gnu_char_ptr_type, gnu_ptr);
              gnu_ptr = build_binary_op (POINTER_PLUS_EXPR, gnu_char_ptr_type,
                                         gnu_ptr, gnu_byte_offset);
            }

          /* If the object was allocated from the default storage pool, the
             alignment was greater than what the allocator provides, and this
             is not a fat or thin pointer, what we have in gnu_ptr here is an
             address dynamically adjusted to match the alignment requirement
             (see build_allocator).  What we need to pass to free is the
             initial allocator's return value, which has been stored just in
             front of the block we have.  */

          if (No (Procedure_To_Call (gnat_node))
              && align > default_allocator_alignment
              && ! TYPE_FAT_OR_THIN_POINTER_P (gnu_ptr_type))
            {
              /* We set GNU_PTR
                 as * (void **)((void *)GNU_PTR - (void *)sizeof(void *))
                 in two steps:  */

              /* GNU_PTR (void *)
                 = (void *)GNU_PTR - (void *)sizeof (void *))  */
              gnu_ptr
                = build_binary_op
                    (POINTER_PLUS_EXPR, ptr_void_type_node,
                     convert (ptr_void_type_node, gnu_ptr),
                     size_int (-POINTER_SIZE/BITS_PER_UNIT));

              /* GNU_PTR (void *) = *(void **)GNU_PTR  */
              gnu_ptr
                = build_unary_op
                    (INDIRECT_REF, NULL_TREE,
                     convert (build_pointer_type (ptr_void_type_node),
                              gnu_ptr));
            }

          gnu_result = build_call_alloc_dealloc (gnu_ptr, gnu_obj_size, align,
                                                 Procedure_To_Call (gnat_node),
                                                 Storage_Pool (gnat_node),
                                                 gnat_node);
        }
      break;

    case N_Raise_Constraint_Error:
    case N_Raise_Program_Error:
    case N_Raise_Storage_Error:
      if (type_annotate_only)
        {
          gnu_result = alloc_stmt_list ();
          break;
        }

      gnu_result_type = get_unpadded_type (Etype (gnat_node));
      gnu_result
        = build_call_raise (UI_To_Int (Reason (gnat_node)), gnat_node,
                            Nkind (gnat_node));

      /* If the type is VOID, this is a statement, so we need to
         generate the code for the call.  Handle a Condition, if there
         is one.  */
      if (TREE_CODE (gnu_result_type) == VOID_TYPE)
        {
          set_expr_location_from_node (gnu_result, gnat_node);

          if (Present (Condition (gnat_node)))
            gnu_result = build3 (COND_EXPR, void_type_node,
                                 gnat_to_gnu (Condition (gnat_node)),
                                 gnu_result, alloc_stmt_list ());
        }
      else
        gnu_result = build1 (NULL_EXPR, gnu_result_type, gnu_result);
      break;

    case N_Validate_Unchecked_Conversion:
      {
        Entity_Id gnat_target_type = Target_Type (gnat_node);
        tree gnu_source_type = gnat_to_gnu_type (Source_Type (gnat_node));
        tree gnu_target_type = gnat_to_gnu_type (gnat_target_type);

        /* No need for any warning in this case.  */
        if (!flag_strict_aliasing)
          ;

        /* If the result is a pointer type, see if we are either converting
           from a non-pointer or from a pointer to a type with a different
           alias set and warn if so.  If the result is defined in the same
           unit as this unchecked conversion, we can allow this because we
           can know to make the pointer type behave properly.  */
        else if (POINTER_TYPE_P (gnu_target_type)
                 && !In_Same_Source_Unit (gnat_target_type, gnat_node)
                 && !No_Strict_Aliasing (Underlying_Type (gnat_target_type)))
          {
            tree gnu_source_desig_type = POINTER_TYPE_P (gnu_source_type)
                                         ? TREE_TYPE (gnu_source_type)
                                         : NULL_TREE;
            tree gnu_target_desig_type = TREE_TYPE (gnu_target_type);

            if ((TYPE_DUMMY_P (gnu_target_desig_type)
                 || get_alias_set (gnu_target_desig_type) != 0)
                && (!POINTER_TYPE_P (gnu_source_type)
                    || (TYPE_DUMMY_P (gnu_source_desig_type)
                        != TYPE_DUMMY_P (gnu_target_desig_type))
                    || (TYPE_DUMMY_P (gnu_source_desig_type)
                        && gnu_source_desig_type != gnu_target_desig_type)
                    || (get_alias_set (gnu_source_desig_type)
                        != get_alias_set (gnu_target_desig_type))))
              {
                post_error_ne
                  ("?possible aliasing problem for type&",
                   gnat_node, Target_Type (gnat_node));
                post_error
                  ("\\?use -fno-strict-aliasing switch for references",
                   gnat_node);
                post_error_ne
                  ("\\?or use `pragma No_Strict_Aliasing (&);`",
                   gnat_node, Target_Type (gnat_node));
              }
          }

        /* But if the result is a fat pointer type, we have no mechanism to
           do that, so we unconditionally warn in problematic cases.  */
        else if (TYPE_FAT_POINTER_P (gnu_target_type))
          {
            tree gnu_source_array_type
              = TYPE_FAT_POINTER_P (gnu_source_type)
                ? TREE_TYPE (TREE_TYPE (TYPE_FIELDS (gnu_source_type)))
                : NULL_TREE;
            tree gnu_target_array_type
              = TREE_TYPE (TREE_TYPE (TYPE_FIELDS (gnu_target_type)));

            if ((TYPE_DUMMY_P (gnu_target_array_type)
                 || get_alias_set (gnu_target_array_type) != 0)
                && (!TYPE_FAT_POINTER_P (gnu_source_type)
                    || (TYPE_DUMMY_P (gnu_source_array_type)
                        != TYPE_DUMMY_P (gnu_target_array_type))
                    || (TYPE_DUMMY_P (gnu_source_array_type)
                        && gnu_source_array_type != gnu_target_array_type)
                    || (get_alias_set (gnu_source_array_type)
                        != get_alias_set (gnu_target_array_type))))
              {
                post_error_ne
                  ("?possible aliasing problem for type&",
                   gnat_node, Target_Type (gnat_node));
                post_error
                  ("\\?use -fno-strict-aliasing switch for references",
                   gnat_node);
              }
          }
      }
      gnu_result = alloc_stmt_list ();
      break;

    case N_Raise_Statement:
    case N_Function_Specification:
    case N_Procedure_Specification:
    case N_Op_Concat:
    case N_Component_Association:
    case N_Task_Body:
    default:
      gcc_assert (type_annotate_only);
      gnu_result = alloc_stmt_list ();
    }

  /* If we pushed our level as part of processing the elaboration routine,
     pop it back now.  */
  if (went_into_elab_proc)
    {
      add_stmt (gnu_result);
      gnat_poplevel ();
      gnu_result = end_stmt_group ();
      current_function_decl = NULL_TREE;
    }

  /* Set the location information on the result if it is a real expression.
     References can be reused for multiple GNAT nodes and they would get
     the location information of their last use.  Note that we may have
     no result if we tried to build a CALL_EXPR node to a procedure with
     no side-effects and optimization is enabled.  */
  if (gnu_result
      && EXPR_P (gnu_result)
      && TREE_CODE (gnu_result) != NOP_EXPR
      && !REFERENCE_CLASS_P (gnu_result))
    set_expr_location_from_node (gnu_result, gnat_node);

  /* If we're supposed to return something of void_type, it means we have
     something we're elaborating for effect, so just return.  */
  if (TREE_CODE (gnu_result_type) == VOID_TYPE)
    return gnu_result;

  /* If the result is a constant that overflows, raise constraint error.  */
  else if (TREE_CODE (gnu_result) == INTEGER_CST
      && TREE_OVERFLOW (gnu_result))
    {
      post_error ("Constraint_Error will be raised at run-time?", gnat_node);

      gnu_result
        = build1 (NULL_EXPR, gnu_result_type,
                  build_call_raise (CE_Overflow_Check_Failed, gnat_node,
                                    N_Raise_Constraint_Error));
    }

  /* If our result has side-effects and is of an unconstrained type,
     make a SAVE_EXPR so that we can be sure it will only be referenced
     once.  Note we must do this before any conversions.  */
  if (TREE_SIDE_EFFECTS (gnu_result)
      && (TREE_CODE (gnu_result_type) == UNCONSTRAINED_ARRAY_TYPE
          || CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_result_type))))
    gnu_result = gnat_stabilize_reference (gnu_result, false);

  /* Now convert the result to the result type, unless we are in one of the
     following cases:

       1. If this is the Name of an assignment statement or a parameter of
          a procedure call, return the result almost unmodified since the
          RHS will have to be converted to our type in that case, unless
          the result type has a simpler size.   Similarly, don't convert
          integral types that are the operands of an unchecked conversion
          since we need to ignore those conversions (for 'Valid).

       2. If we have a label (which doesn't have any well-defined type), a
          field or an error, return the result almost unmodified.  Also don't
          do the conversion if the result type involves a PLACEHOLDER_EXPR in
          its size since those are the cases where the front end may have the
          type wrong due to "instantiating" the unconstrained record with
          discriminant values.  Similarly, if the two types are record types
          with the same name don't convert.  This will be the case when we are
          converting from a packable version of a type to its original type and
          we need those conversions to be NOPs in order for assignments into
          these types to work properly.

       3. If the type is void or if we have no result, return error_mark_node
          to show we have no result.

       4. Finally, if the type of the result is already correct.  */

  if (Present (Parent (gnat_node))
      && ((Nkind (Parent (gnat_node)) == N_Assignment_Statement
           && Name (Parent (gnat_node)) == gnat_node)
          || (Nkind (Parent (gnat_node)) == N_Procedure_Call_Statement
              && Name (Parent (gnat_node)) != gnat_node)
          || Nkind (Parent (gnat_node)) == N_Parameter_Association
          || (Nkind (Parent (gnat_node)) == N_Unchecked_Type_Conversion
              && !AGGREGATE_TYPE_P (gnu_result_type)
              && !AGGREGATE_TYPE_P (TREE_TYPE (gnu_result))))
      && !(TYPE_SIZE (gnu_result_type)
           && TYPE_SIZE (TREE_TYPE (gnu_result))
           && (AGGREGATE_TYPE_P (gnu_result_type)
               == AGGREGATE_TYPE_P (TREE_TYPE (gnu_result)))
           && ((TREE_CODE (TYPE_SIZE (gnu_result_type)) == INTEGER_CST
                && (TREE_CODE (TYPE_SIZE (TREE_TYPE (gnu_result)))
                    != INTEGER_CST))
               || (TREE_CODE (TYPE_SIZE (gnu_result_type)) != INTEGER_CST
                   && !CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_result_type))
                   && (CONTAINS_PLACEHOLDER_P
                       (TYPE_SIZE (TREE_TYPE (gnu_result))))))
           && !(TREE_CODE (gnu_result_type) == RECORD_TYPE
                && TYPE_JUSTIFIED_MODULAR_P (gnu_result_type))))
    {
      /* Remove padding only if the inner object is of self-referential
         size: in that case it must be an object of unconstrained type
         with a default discriminant and we want to avoid copying too
         much data.  */
      if (TREE_CODE (TREE_TYPE (gnu_result)) == RECORD_TYPE
          && TYPE_IS_PADDING_P (TREE_TYPE (gnu_result))
          && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (TREE_TYPE (TYPE_FIELDS
                                     (TREE_TYPE (gnu_result))))))
        gnu_result = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_result))),
                              gnu_result);
    }

  else if (TREE_CODE (gnu_result) == LABEL_DECL
           || TREE_CODE (gnu_result) == FIELD_DECL
           || TREE_CODE (gnu_result) == ERROR_MARK
           || (TYPE_SIZE (gnu_result_type)
               && TREE_CODE (TYPE_SIZE (gnu_result_type)) != INTEGER_CST
               && TREE_CODE (gnu_result) != INDIRECT_REF
               && CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_result_type)))
           || ((TYPE_NAME (gnu_result_type)
                == TYPE_NAME (TREE_TYPE (gnu_result)))
               && TREE_CODE (gnu_result_type) == RECORD_TYPE
               && TREE_CODE (TREE_TYPE (gnu_result)) == RECORD_TYPE))
    {
      /* Remove any padding.  */
      if (TREE_CODE (TREE_TYPE (gnu_result)) == RECORD_TYPE
          && TYPE_IS_PADDING_P (TREE_TYPE (gnu_result)))
        gnu_result = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_result))),
                              gnu_result);
    }

  else if (gnu_result == error_mark_node || gnu_result_type == void_type_node)
    gnu_result = error_mark_node;

  else if (gnu_result_type != TREE_TYPE (gnu_result))
    gnu_result = convert (gnu_result_type, gnu_result);

  /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result.  */
  while ((TREE_CODE (gnu_result) == NOP_EXPR
          || TREE_CODE (gnu_result) == NON_LVALUE_EXPR)
         && TREE_TYPE (TREE_OPERAND (gnu_result, 0)) == TREE_TYPE (gnu_result))
    gnu_result = TREE_OPERAND (gnu_result, 0);

  return gnu_result;
}
\f
/* Subroutine of above to push the exception label stack.  GNU_STACK is
   a pointer to the stack to update and GNAT_LABEL, if present, is the
   label to push onto the stack.  */

static void
push_exception_label_stack (tree *gnu_stack, Entity_Id gnat_label)
{
  tree gnu_label = (Present (gnat_label)
                    ? gnat_to_gnu_entity (gnat_label, NULL_TREE, 0)
                    : NULL_TREE);

  *gnu_stack = tree_cons (NULL_TREE, gnu_label, *gnu_stack);
}
\f
/* Record the current code position in GNAT_NODE.  */

static void
record_code_position (Node_Id gnat_node)
{
  tree stmt_stmt = build1 (STMT_STMT, void_type_node, NULL_TREE);

  add_stmt_with_node (stmt_stmt, gnat_node);
  save_gnu_tree (gnat_node, stmt_stmt, true);
}

/* Insert the code for GNAT_NODE at the position saved for that node.  */

static void
insert_code_for (Node_Id gnat_node)
{
  STMT_STMT_STMT (get_gnu_tree (gnat_node)) = gnat_to_gnu (gnat_node);
  save_gnu_tree (gnat_node, NULL_TREE, true);
}
\f
/* Start a new statement group chained to the previous group.  */

void
start_stmt_group (void)
{
  struct stmt_group *group = stmt_group_free_list;

  /* First see if we can get one from the free list.  */
  if (group)
    stmt_group_free_list = group->previous;
  else
    group = (struct stmt_group *) ggc_alloc (sizeof (struct stmt_group));

  group->previous = current_stmt_group;
  group->stmt_list = group->block = group->cleanups = NULL_TREE;
  current_stmt_group = group;
}

/* Add GNU_STMT to the current statement group.  */

void
add_stmt (tree gnu_stmt)
{
  append_to_statement_list (gnu_stmt, &current_stmt_group->stmt_list);
}

/* Similar, but set the location of GNU_STMT to that of GNAT_NODE.  */

void
add_stmt_with_node (tree gnu_stmt, Node_Id gnat_node)
{
  if (Present (gnat_node))
    set_expr_location_from_node (gnu_stmt, gnat_node);
  add_stmt (gnu_stmt);
}

/* Add a declaration statement for GNU_DECL to the current statement group.
   Get SLOC from Entity_Id.  */

void
add_decl_expr (tree gnu_decl, Entity_Id gnat_entity)
{
  tree type = TREE_TYPE (gnu_decl);
  tree gnu_stmt, gnu_init, t;

  /* If this is a variable that Gigi is to ignore, we may have been given
     an ERROR_MARK.  So test for it.  We also might have been given a
     reference for a renaming.  So only do something for a decl.  Also
     ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE.  */
  if (!DECL_P (gnu_decl)
      || (TREE_CODE (gnu_decl) == TYPE_DECL
          && TREE_CODE (type) == UNCONSTRAINED_ARRAY_TYPE))
    return;

  gnu_stmt = build1 (DECL_EXPR, void_type_node, gnu_decl);

  /* If we are global, we don't want to actually output the DECL_EXPR for
     this decl since we already have evaluated the expressions in the
     sizes and positions as globals and doing it again would be wrong.  */
  if (global_bindings_p ())
    {
      /* Mark everything as used to prevent node sharing with subprograms.
         Note that walk_tree knows how to deal with TYPE_DECL, but neither
         VAR_DECL nor CONST_DECL.  This appears to be somewhat arbitrary.  */
      mark_visited (&gnu_stmt);
      if (TREE_CODE (gnu_decl) == VAR_DECL
          || TREE_CODE (gnu_decl) == CONST_DECL)
        {
          mark_visited (&DECL_SIZE (gnu_decl));
          mark_visited (&DECL_SIZE_UNIT (gnu_decl));
          mark_visited (&DECL_INITIAL (gnu_decl));
        }
      /* In any case, we have to deal with our own TYPE_ADA_SIZE field.  */
      if (TREE_CODE (gnu_decl) == TYPE_DECL
          && (TREE_CODE (type) == RECORD_TYPE
              || TREE_CODE (type) == UNION_TYPE
              || TREE_CODE (type) == QUAL_UNION_TYPE)
          && (t = TYPE_ADA_SIZE (type)))
        mark_visited (&t);
    }
  else
    add_stmt_with_node (gnu_stmt, gnat_entity);

  /* If this is a variable and an initializer is attached to it, it must be
     valid for the context.  Similar to init_const in create_var_decl_1.  */
  if (TREE_CODE (gnu_decl) == VAR_DECL
      && (gnu_init = DECL_INITIAL (gnu_decl)) != NULL_TREE
      && (!gnat_types_compatible_p (type, TREE_TYPE (gnu_init))
          || (TREE_STATIC (gnu_decl)
              && !initializer_constant_valid_p (gnu_init,
                                                TREE_TYPE (gnu_init)))))
    {
      /* If GNU_DECL has a padded type, convert it to the unpadded
         type so the assignment is done properly.  */
      if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
        t = convert (TREE_TYPE (TYPE_FIELDS (type)), gnu_decl);
      else
        t = gnu_decl;

      gnu_stmt = build_binary_op (MODIFY_EXPR, NULL_TREE, t, gnu_init);

      DECL_INITIAL (gnu_decl) = NULL_TREE;
      if (TREE_READONLY (gnu_decl))
        {
          TREE_READONLY (gnu_decl) = 0;
          DECL_READONLY_ONCE_ELAB (gnu_decl) = 1;
        }

      add_stmt_with_node (gnu_stmt, gnat_entity);
    }
}

/* Callback for walk_tree to mark the visited trees rooted at *TP.  */

static tree
mark_visited_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
{
  if (TREE_VISITED (*tp))
    *walk_subtrees = 0;

  /* Don't mark a dummy type as visited because we want to mark its sizes
     and fields once it's filled in.  */
  else if (!TYPE_IS_DUMMY_P (*tp))
    TREE_VISITED (*tp) = 1;

  if (TYPE_P (*tp))
    TYPE_SIZES_GIMPLIFIED (*tp) = 1;

  return NULL_TREE;
}

/* Utility function to unshare expressions wrapped up in a SAVE_EXPR.  */

static tree
unshare_save_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
                   void *data ATTRIBUTE_UNUSED)
{
  tree t = *tp;

  if (TREE_CODE (t) == SAVE_EXPR)
    TREE_OPERAND (t, 0) = unshare_expr (TREE_OPERAND (t, 0));

  return NULL_TREE;
}

/* Mark nodes rooted at *TP with TREE_VISITED and types as having their
   sized gimplified.  We use this to indicate all variable sizes and
   positions in global types may not be shared by any subprogram.  */

void
mark_visited (tree *tp)
{
  walk_tree (tp, mark_visited_r, NULL, NULL);
}

/* Add GNU_CLEANUP, a cleanup action, to the current code group and
   set its location to that of GNAT_NODE if present.  */

static void
add_cleanup (tree gnu_cleanup, Node_Id gnat_node)
{
  if (Present (gnat_node))
    set_expr_location_from_node (gnu_cleanup, gnat_node);
  append_to_statement_list (gnu_cleanup, &current_stmt_group->cleanups);
}

/* Set the BLOCK node corresponding to the current code group to GNU_BLOCK.  */

void
set_block_for_group (tree gnu_block)
{
  gcc_assert (!current_stmt_group->block);
  current_stmt_group->block = gnu_block;
}

/* Return code corresponding to the current code group.  It is normally
   a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
   BLOCK or cleanups were set.  */

tree
end_stmt_group (void)
{
  struct stmt_group *group = current_stmt_group;
  tree gnu_retval = group->stmt_list;

  /* If this is a null list, allocate a new STATEMENT_LIST.  Then, if there
     are cleanups, make a TRY_FINALLY_EXPR.  Last, if there is a BLOCK,
     make a BIND_EXPR.  Note that we nest in that because the cleanup may
     reference variables in the block.  */
  if (gnu_retval == NULL_TREE)
    gnu_retval = alloc_stmt_list ();

  if (group->cleanups)
    gnu_retval = build2 (TRY_FINALLY_EXPR, void_type_node, gnu_retval,
                         group->cleanups);

  if (current_stmt_group->block)
    gnu_retval = build3 (BIND_EXPR, void_type_node, BLOCK_VARS (group->block),
                         gnu_retval, group->block);

  /* Remove this group from the stack and add it to the free list.  */
  current_stmt_group = group->previous;
  group->previous = stmt_group_free_list;
  stmt_group_free_list = group;

  return gnu_retval;
}

/* Add a list of statements from GNAT_LIST, a possibly-empty list of
   statements.*/

static void
add_stmt_list (List_Id gnat_list)
{
  Node_Id gnat_node;

  if (Present (gnat_list))
    for (gnat_node = First (gnat_list); Present (gnat_node);
         gnat_node = Next (gnat_node))
      add_stmt (gnat_to_gnu (gnat_node));
}

/* Build a tree from GNAT_LIST, a possibly-empty list of statements.
   If BINDING_P is true, push and pop a binding level around the list.  */

static tree
build_stmt_group (List_Id gnat_list, bool binding_p)
{
  start_stmt_group ();
  if (binding_p)
    gnat_pushlevel ();

  add_stmt_list (gnat_list);
  if (binding_p)
    gnat_poplevel ();

  return end_stmt_group ();
}
\f
/* Push and pop routines for stacks.  We keep a free list around so we
   don't waste tree nodes.  */

static void
push_stack (tree *gnu_stack_ptr, tree gnu_purpose, tree gnu_value)
{
  tree gnu_node = gnu_stack_free_list;

  if (gnu_node)
    {
      gnu_stack_free_list = TREE_CHAIN (gnu_node);
      TREE_CHAIN (gnu_node) = *gnu_stack_ptr;
      TREE_PURPOSE (gnu_node) = gnu_purpose;
      TREE_VALUE (gnu_node) = gnu_value;
    }
  else
    gnu_node = tree_cons (gnu_purpose, gnu_value, *gnu_stack_ptr);

  *gnu_stack_ptr = gnu_node;
}

static void
pop_stack (tree *gnu_stack_ptr)
{
  tree gnu_node = *gnu_stack_ptr;

  *gnu_stack_ptr = TREE_CHAIN (gnu_node);
  TREE_CHAIN (gnu_node) = gnu_stack_free_list;
  gnu_stack_free_list = gnu_node;
}
\f
/* Generate GIMPLE in place for the expression at *EXPR_P.  */

int
gnat_gimplify_expr (tree *expr_p, tree *pre_p, tree *post_p ATTRIBUTE_UNUSED)
{
  tree expr = *expr_p;
  tree op;

  if (IS_ADA_STMT (expr))
    return gnat_gimplify_stmt (expr_p);

  switch (TREE_CODE (expr))
    {
    case NULL_EXPR:
      /* If this is for a scalar, just make a VAR_DECL for it.  If for
         an aggregate, get a null pointer of the appropriate type and
         dereference it.  */
      if (AGGREGATE_TYPE_P (TREE_TYPE (expr)))
        *expr_p = build1 (INDIRECT_REF, TREE_TYPE (expr),
                          convert (build_pointer_type (TREE_TYPE (expr)),
                                   integer_zero_node));
      else
        {
          *expr_p = create_tmp_var (TREE_TYPE (expr), NULL);
          TREE_NO_WARNING (*expr_p) = 1;
        }

      gimplify_and_add (TREE_OPERAND (expr, 0), pre_p);
      return GS_OK;

    case UNCONSTRAINED_ARRAY_REF:
      /* We should only do this if we are just elaborating for side-effects,
         but we can't know that yet.  */
      *expr_p = TREE_OPERAND (*expr_p, 0);
      return GS_OK;

    case ADDR_EXPR:
      op = TREE_OPERAND (expr, 0);

      /* If we're taking the address of a constant CONSTRUCTOR, force it to
         be put into static memory.  We know it's going to be readonly given
         the semantics we have and it's required to be static memory in
         the case when the reference is in an elaboration procedure.   */
      if (TREE_CODE (op) == CONSTRUCTOR && TREE_CONSTANT (op))
        {
          tree new_var = create_tmp_var (TREE_TYPE (op), "C");

          TREE_READONLY (new_var) = 1;
          TREE_STATIC (new_var) = 1;
          TREE_ADDRESSABLE (new_var) = 1;
          DECL_INITIAL (new_var) = op;

          TREE_OPERAND (expr, 0) = new_var;
          recompute_tree_invariant_for_addr_expr (expr);
          return GS_ALL_DONE;
        }

      /* If we are taking the address of a SAVE_EXPR, we are typically
         processing a misaligned argument to be passed by reference in a
         procedure call.  We just mark the operand as addressable + not
         readonly here and let the common gimplifier code perform the
         temporary creation, initialization, and "instantiation" in place of
         the SAVE_EXPR in further operands, in particular in the copy back
         code inserted after the call.  */
      else if (TREE_CODE (op) == SAVE_EXPR)
        {
          TREE_ADDRESSABLE (op) = 1;
          TREE_READONLY (op) = 0;
        }

      /* We let the gimplifier process &COND_EXPR and expect it to yield the
         address of the selected operand when it is addressable.  Besides, we
         also expect addressable_p to only let COND_EXPRs where both arms are
         addressable reach here.  */
      else if (TREE_CODE (op) == COND_EXPR)
        ;

      /* Otherwise, if we are taking the address of something that is neither
         reference, declaration, or constant, make a variable for the operand
         here and then take its address.  If we don't do it this way, we may
         confuse the gimplifier because it needs to know the variable is
         addressable at this point.  This duplicates code in
         internal_get_tmp_var, which is unfortunate.  */
      else if (TREE_CODE_CLASS (TREE_CODE (op)) != tcc_reference
               && TREE_CODE_CLASS (TREE_CODE (op)) != tcc_declaration
               && TREE_CODE_CLASS (TREE_CODE (op)) != tcc_constant)
        {
          tree new_var = create_tmp_var (TREE_TYPE (op), "A");
          tree mod = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (op), new_var, op);

          TREE_ADDRESSABLE (new_var) = 1;

          if (EXPR_HAS_LOCATION (op))
            SET_EXPR_LOCUS (mod, EXPR_LOCUS (op));

          gimplify_and_add (mod, pre_p);
          TREE_OPERAND (expr, 0) = new_var;
          recompute_tree_invariant_for_addr_expr (expr);
          return GS_ALL_DONE;
        }

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

    default:
      return GS_UNHANDLED;
    }
}

/* Generate GIMPLE in place for the statement at *STMT_P.  */

static enum gimplify_status
gnat_gimplify_stmt (tree *stmt_p)
{
  tree stmt = *stmt_p;

  switch (TREE_CODE (stmt))
    {
    case STMT_STMT:
      *stmt_p = STMT_STMT_STMT (stmt);
      return GS_OK;

    case LOOP_STMT:
      {
        tree gnu_start_label = create_artificial_label ();
        tree gnu_end_label = LOOP_STMT_LABEL (stmt);
        tree t;

        /* Set to emit the statements of the loop.  */
        *stmt_p = NULL_TREE;

        /* We first emit the start label and then a conditional jump to
           the end label if there's a top condition, then the body of the
           loop, then a conditional branch to the end label, then the update,
           if any, and finally a jump to the start label and the definition
           of the end label.  */
        append_to_statement_list (build1 (LABEL_EXPR, void_type_node,
                                          gnu_start_label),
                                  stmt_p);

        if (LOOP_STMT_TOP_COND (stmt))
          append_to_statement_list (build3 (COND_EXPR, void_type_node,
                                            LOOP_STMT_TOP_COND (stmt),
                                            alloc_stmt_list (),
                                            build1 (GOTO_EXPR,
                                                    void_type_node,
                                                    gnu_end_label)),
                                    stmt_p);

        append_to_statement_list (LOOP_STMT_BODY (stmt), stmt_p);

        if (LOOP_STMT_BOT_COND (stmt))
          append_to_statement_list (build3 (COND_EXPR, void_type_node,
                                            LOOP_STMT_BOT_COND (stmt),
                                            alloc_stmt_list (),
                                            build1 (GOTO_EXPR,
                                                    void_type_node,
                                                    gnu_end_label)),
                                    stmt_p);

        if (LOOP_STMT_UPDATE (stmt))
          append_to_statement_list (LOOP_STMT_UPDATE (stmt), stmt_p);

        t = build1 (GOTO_EXPR, void_type_node, gnu_start_label);
        set_expr_location (t, DECL_SOURCE_LOCATION (gnu_end_label));
        append_to_statement_list (t, stmt_p);

        append_to_statement_list (build1 (LABEL_EXPR, void_type_node,
                                          gnu_end_label),
                                  stmt_p);
        return GS_OK;
      }

    case EXIT_STMT:
      /* Build a statement to jump to the corresponding end label, then
         see if it needs to be conditional.  */
      *stmt_p = build1 (GOTO_EXPR, void_type_node, EXIT_STMT_LABEL (stmt));
      if (EXIT_STMT_COND (stmt))
        *stmt_p = build3 (COND_EXPR, void_type_node,
                          EXIT_STMT_COND (stmt), *stmt_p, alloc_stmt_list ());
      return GS_OK;

    default:
      gcc_unreachable ();
    }
}
\f
/* Force references to each of the entities in packages withed by GNAT_NODE.
   Operate recursively but check that we aren't elaborating something more
   than once.

   This routine is exclusively called in type_annotate mode, to compute DDA
   information for types in withed units, for ASIS use.  */

static void
elaborate_all_entities (Node_Id gnat_node)
{
  Entity_Id gnat_with_clause, gnat_entity;

  /* Process each unit only once.  As we trace the context of all relevant
     units transitively, including generic bodies, we may encounter the
     same generic unit repeatedly.  */
  if (!present_gnu_tree (gnat_node))
     save_gnu_tree (gnat_node, integer_zero_node, true);

  /* Save entities in all context units.  A body may have an implicit_with
     on its own spec, if the context includes a child unit, so don't save
     the spec twice.  */
  for (gnat_with_clause = First (Context_Items (gnat_node));
       Present (gnat_with_clause);
       gnat_with_clause = Next (gnat_with_clause))
    if (Nkind (gnat_with_clause) == N_With_Clause
        && !present_gnu_tree (Library_Unit (gnat_with_clause))
        && Library_Unit (gnat_with_clause) != Library_Unit (Cunit (Main_Unit)))
      {
        elaborate_all_entities (Library_Unit (gnat_with_clause));

        if (Ekind (Entity (Name (gnat_with_clause))) == E_Package)
          {
            for (gnat_entity = First_Entity (Entity (Name (gnat_with_clause)));
                 Present (gnat_entity);
                 gnat_entity = Next_Entity (gnat_entity))
              if (Is_Public (gnat_entity)
                  && Convention (gnat_entity) != Convention_Intrinsic
                  && Ekind (gnat_entity) != E_Package
                  && Ekind (gnat_entity) != E_Package_Body
                  && Ekind (gnat_entity) != E_Operator
                  && !(IN (Ekind (gnat_entity), Type_Kind)
                       && !Is_Frozen (gnat_entity))
                  && !((Ekind (gnat_entity) == E_Procedure
                        || Ekind (gnat_entity) == E_Function)
                       && Is_Intrinsic_Subprogram (gnat_entity))
                  && !IN (Ekind (gnat_entity), Named_Kind)
                  && !IN (Ekind (gnat_entity), Generic_Unit_Kind))
                gnat_to_gnu_entity (gnat_entity, NULL_TREE, 0);
          }
        else if (Ekind (Entity (Name (gnat_with_clause))) == E_Generic_Package)
          {
            Node_Id gnat_body
              = Corresponding_Body (Unit (Library_Unit (gnat_with_clause)));

            /* Retrieve compilation unit node of generic body.  */
            while (Present (gnat_body)
                   && Nkind (gnat_body) != N_Compilation_Unit)
              gnat_body = Parent (gnat_body);

            /* If body is available, elaborate its context.  */
            if (Present (gnat_body))
              elaborate_all_entities (gnat_body);
          }
      }

  if (Nkind (Unit (gnat_node)) == N_Package_Body)
    elaborate_all_entities (Library_Unit (gnat_node));
}
\f
/* Do the processing of N_Freeze_Entity, GNAT_NODE.  */

static void
process_freeze_entity (Node_Id gnat_node)
{
  Entity_Id gnat_entity = Entity (gnat_node);
  tree gnu_old;
  tree gnu_new;
  tree gnu_init
    = (Nkind (Declaration_Node (gnat_entity)) == N_Object_Declaration
       && present_gnu_tree (Declaration_Node (gnat_entity)))
      ? get_gnu_tree (Declaration_Node (gnat_entity)) : NULL_TREE;

  /* If this is a package, need to generate code for the package.  */
  if (Ekind (gnat_entity) == E_Package)
    {
      insert_code_for
        (Parent (Corresponding_Body
                 (Parent (Declaration_Node (gnat_entity)))));
      return;
    }

  /* Check for old definition after the above call.  This Freeze_Node
     might be for one its Itypes.  */
  gnu_old
    = present_gnu_tree (gnat_entity) ? get_gnu_tree (gnat_entity) : 0;

  /* If this entity has an Address representation clause, GNU_OLD is the
     address, so discard it here. */
  if (Present (Address_Clause (gnat_entity)))
    gnu_old = 0;

  /* Don't do anything for class-wide types they are always
     transformed into their root type.  */
  if (Ekind (gnat_entity) == E_Class_Wide_Type
      || (Ekind (gnat_entity) == E_Class_Wide_Subtype
          && Present (Equivalent_Type (gnat_entity))))
    return;

  /* Don't do anything for subprograms that may have been elaborated before
     their freeze nodes.  This can happen, for example because of an inner call
     in an instance body, or a previous compilation of a spec for inlining
     purposes. */
  if (gnu_old
      && ((TREE_CODE (gnu_old) == FUNCTION_DECL
           && (Ekind (gnat_entity) == E_Function
               || Ekind (gnat_entity) == E_Procedure))
          || (gnu_old
              && TREE_CODE (TREE_TYPE (gnu_old)) == FUNCTION_TYPE
              && Ekind (gnat_entity) == E_Subprogram_Type)))
    return;

  /* If we have a non-dummy type old tree, we have nothing to do, except
     aborting if this is the public view of a private type whose full view was
     not delayed, as this node was never delayed as it should have been.  We
     let this happen for concurrent types and their Corresponding_Record_Type,
     however, because each might legitimately be elaborated before it's own
     freeze node, e.g. while processing the other.  */
  if (gnu_old
      && !(TREE_CODE (gnu_old) == TYPE_DECL
           && TYPE_IS_DUMMY_P (TREE_TYPE (gnu_old))))
    {
      gcc_assert ((IN (Ekind (gnat_entity), Incomplete_Or_Private_Kind)
                   && Present (Full_View (gnat_entity))
                   && No (Freeze_Node (Full_View (gnat_entity))))
                  || Is_Concurrent_Type (gnat_entity)
                  || (IN (Ekind (gnat_entity), Record_Kind)
                      && Is_Concurrent_Record_Type (gnat_entity)));
      return;
    }

  /* Reset the saved tree, if any, and elaborate the object or type for real.
     If there is a full declaration, elaborate it and copy the type to
     GNAT_ENTITY.  Likewise if this is the record subtype corresponding to
     a class wide type or subtype. */
  if (gnu_old)
    {
      save_gnu_tree (gnat_entity, NULL_TREE, false);
      if (IN (Ekind (gnat_entity), Incomplete_Or_Private_Kind)
          && Present (Full_View (gnat_entity))
          && present_gnu_tree (Full_View (gnat_entity)))
        save_gnu_tree (Full_View (gnat_entity), NULL_TREE, false);
      if (Present (Class_Wide_Type (gnat_entity))
          && Class_Wide_Type (gnat_entity) != gnat_entity)
        save_gnu_tree (Class_Wide_Type (gnat_entity), NULL_TREE, false);
    }

  if (IN (Ekind (gnat_entity), Incomplete_Or_Private_Kind)
      && Present (Full_View (gnat_entity)))
    {
      gnu_new = gnat_to_gnu_entity (Full_View (gnat_entity), NULL_TREE, 1);

      /* Propagate back-annotations from full view to partial view.  */
      if (Unknown_Alignment (gnat_entity))
        Set_Alignment (gnat_entity, Alignment (Full_View (gnat_entity)));

      if (Unknown_Esize (gnat_entity))
        Set_Esize (gnat_entity, Esize (Full_View (gnat_entity)));

      if (Unknown_RM_Size (gnat_entity))
        Set_RM_Size (gnat_entity, RM_Size (Full_View (gnat_entity)));

      /* The above call may have defined this entity (the simplest example
         of this is when we have a private enumeral type since the bounds
         will have the public view.  */
      if (!present_gnu_tree (gnat_entity))
        save_gnu_tree (gnat_entity, gnu_new, false);
      if (Present (Class_Wide_Type (gnat_entity))
          && Class_Wide_Type (gnat_entity) != gnat_entity)
        save_gnu_tree (Class_Wide_Type (gnat_entity), gnu_new, false);
    }
  else
    gnu_new = gnat_to_gnu_entity (gnat_entity, gnu_init, 1);

  /* If we've made any pointers to the old version of this type, we
     have to update them.  */
  if (gnu_old)
    update_pointer_to (TYPE_MAIN_VARIANT (TREE_TYPE (gnu_old)),
                       TREE_TYPE (gnu_new));
}
\f
/* Process the list of inlined subprograms of GNAT_NODE, which is an
   N_Compilation_Unit.  */

static void
process_inlined_subprograms (Node_Id gnat_node)
{
  Entity_Id gnat_entity;
  Node_Id gnat_body;

  /* If we can inline, generate RTL for all the inlined subprograms.
     Define the entity first so we set DECL_EXTERNAL.  */
  if (optimize > 0 && !flag_really_no_inline)
    for (gnat_entity = First_Inlined_Subprogram (gnat_node);
         Present (gnat_entity);
         gnat_entity = Next_Inlined_Subprogram (gnat_entity))
      {
        gnat_body = Parent (Declaration_Node (gnat_entity));

        if (Nkind (gnat_body) != N_Subprogram_Body)
          {
            /* ??? This really should always be Present.  */
            if (No (Corresponding_Body (gnat_body)))
              continue;

            gnat_body
              = Parent (Declaration_Node (Corresponding_Body (gnat_body)));
          }

        if (Present (gnat_body))
          {
            gnat_to_gnu_entity (gnat_entity, NULL_TREE, 0);
            add_stmt (gnat_to_gnu (gnat_body));
          }
      }
}
\f
/* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
   We make two passes, one to elaborate anything other than bodies (but
   we declare a function if there was no spec).  The second pass
   elaborates the bodies.

   GNAT_END_LIST gives the element in the list past the end.  Normally,
   this is Empty, but can be First_Real_Statement for a
   Handled_Sequence_Of_Statements.

   We make a complete pass through both lists if PASS1P is true, then make
   the second pass over both lists if PASS2P is true.  The lists usually
   correspond to the public and private parts of a package.  */

static void
process_decls (List_Id gnat_decls, List_Id gnat_decls2,
               Node_Id gnat_end_list, bool pass1p, bool pass2p)
{
  List_Id gnat_decl_array[2];
  Node_Id gnat_decl;
  int i;

  gnat_decl_array[0] = gnat_decls, gnat_decl_array[1] = gnat_decls2;

  if (pass1p)
    for (i = 0; i <= 1; i++)
      if (Present (gnat_decl_array[i]))
        for (gnat_decl = First (gnat_decl_array[i]);
             gnat_decl != gnat_end_list; gnat_decl = Next (gnat_decl))
          {
            /* For package specs, we recurse inside the declarations,
               thus taking the two pass approach inside the boundary.  */
            if (Nkind (gnat_decl) == N_Package_Declaration
                && (Nkind (Specification (gnat_decl)
                           == N_Package_Specification)))
              process_decls (Visible_Declarations (Specification (gnat_decl)),
                             Private_Declarations (Specification (gnat_decl)),
                             Empty, true, false);

            /* Similarly for any declarations in the actions of a
               freeze node.  */
            else if (Nkind (gnat_decl) == N_Freeze_Entity)
              {
                process_freeze_entity (gnat_decl);
                process_decls (Actions (gnat_decl), Empty, Empty, true, false);
              }

            /* Package bodies with freeze nodes get their elaboration deferred
               until the freeze node, but the code must be placed in the right
               place, so record the code position now.  */
            else if (Nkind (gnat_decl) == N_Package_Body
                     && Present (Freeze_Node (Corresponding_Spec (gnat_decl))))
              record_code_position (gnat_decl);

            else if (Nkind (gnat_decl) == N_Package_Body_Stub
                     && Present (Library_Unit (gnat_decl))
                     && Present (Freeze_Node
                                 (Corresponding_Spec
                                  (Proper_Body (Unit
                                                (Library_Unit (gnat_decl)))))))
              record_code_position
                (Proper_Body (Unit (Library_Unit (gnat_decl))));

            /* We defer most subprogram bodies to the second pass.  */
            else if (Nkind (gnat_decl) == N_Subprogram_Body)
              {
                if (Acts_As_Spec (gnat_decl))
                  {
                    Node_Id gnat_subprog_id = Defining_Entity (gnat_decl);

                    if (Ekind (gnat_subprog_id) != E_Generic_Procedure
                        && Ekind (gnat_subprog_id) != E_Generic_Function)
                      gnat_to_gnu_entity (gnat_subprog_id, NULL_TREE, 1);
                  }
              }
            /* For bodies and stubs that act as their own specs, the entity
               itself must be elaborated in the first pass, because it may
               be used in other declarations. */
            else if (Nkind (gnat_decl) == N_Subprogram_Body_Stub)
              {
                  Node_Id gnat_subprog_id =
                     Defining_Entity (Specification (gnat_decl));

                    if (Ekind (gnat_subprog_id) != E_Subprogram_Body
                        && Ekind (gnat_subprog_id) != E_Generic_Procedure
                        && Ekind (gnat_subprog_id) != E_Generic_Function)
                      gnat_to_gnu_entity (gnat_subprog_id, NULL_TREE, 1);
               }

            /* Concurrent stubs stand for the corresponding subprogram bodies,
               which are deferred like other bodies.  */
            else if (Nkind (gnat_decl) == N_Task_Body_Stub
                     || Nkind (gnat_decl) == N_Protected_Body_Stub)
              ;
            else
              add_stmt (gnat_to_gnu (gnat_decl));
          }

  /* Here we elaborate everything we deferred above except for package bodies,
     which are elaborated at their freeze nodes.  Note that we must also
     go inside things (package specs and freeze nodes) the first pass did.  */
  if (pass2p)
    for (i = 0; i <= 1; i++)
      if (Present (gnat_decl_array[i]))
        for (gnat_decl = First (gnat_decl_array[i]);
             gnat_decl != gnat_end_list; gnat_decl = Next (gnat_decl))
          {
            if (Nkind (gnat_decl) == N_Subprogram_Body
                || Nkind (gnat_decl) == N_Subprogram_Body_Stub
                || Nkind (gnat_decl) == N_Task_Body_Stub
                || Nkind (gnat_decl) == N_Protected_Body_Stub)
              add_stmt (gnat_to_gnu (gnat_decl));

            else if (Nkind (gnat_decl) == N_Package_Declaration
                     && (Nkind (Specification (gnat_decl)
                                == N_Package_Specification)))
              process_decls (Visible_Declarations (Specification (gnat_decl)),
                             Private_Declarations (Specification (gnat_decl)),
                             Empty, false, true);

            else if (Nkind (gnat_decl) == N_Freeze_Entity)
              process_decls (Actions (gnat_decl), Empty, Empty, false, true);
          }
}
\f
/* Emit code for a range check. GNU_EXPR is the expression to be checked,
   GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
   which we have to check. */

static tree
emit_range_check (tree gnu_expr, Entity_Id gnat_range_type)
{
  tree gnu_range_type = get_unpadded_type (gnat_range_type);
  tree gnu_low  = TYPE_MIN_VALUE (gnu_range_type);
  tree gnu_high = TYPE_MAX_VALUE (gnu_range_type);
  tree gnu_compare_type = get_base_type (TREE_TYPE (gnu_expr));

  /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
     This can for example happen when translating 'Val or 'Value.  */
  if (gnu_compare_type == gnu_range_type)
    return gnu_expr;

  /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
     we can't do anything since we might be truncating the bounds.  No
     check is needed in this case.  */
  if (INTEGRAL_TYPE_P (TREE_TYPE (gnu_expr))
      && (TYPE_PRECISION (gnu_compare_type)
          < TYPE_PRECISION (get_base_type (gnu_range_type))))
    return gnu_expr;

  /* Checked expressions must be evaluated only once. */
  gnu_expr = protect_multiple_eval (gnu_expr);

  /* There's no good type to use here, so we might as well use
     integer_type_node. Note that the form of the check is
        (not (expr >= lo)) or (not (expr <= hi))
      the reason for this slightly convoluted form is that NaNs
      are not considered to be in range in the float case. */
  return emit_check
    (build_binary_op (TRUTH_ORIF_EXPR, integer_type_node,
                      invert_truthvalue
                      (build_binary_op (GE_EXPR, integer_type_node,
                                       convert (gnu_compare_type, gnu_expr),
                                       convert (gnu_compare_type, gnu_low))),
                      invert_truthvalue
                      (build_binary_op (LE_EXPR, integer_type_node,
                                        convert (gnu_compare_type, gnu_expr),
                                        convert (gnu_compare_type,
                                                 gnu_high)))),
     gnu_expr, CE_Range_Check_Failed);
}
\f
/* Emit code for an index check. GNU_ARRAY_OBJECT is the array object
   which we are about to index, GNU_EXPR is the index expression to be
   checked, GNU_LOW and GNU_HIGH are the lower and upper bounds
   against which GNU_EXPR has to be checked. Note that for index
   checking we cannot use the emit_range_check function (although very
   similar code needs to be generated in both cases) since for index
   checking the array type against which we are checking the indices
   may be unconstrained and consequently we need to retrieve the
   actual index bounds from the array object itself
   (GNU_ARRAY_OBJECT). The place where we need to do that is in
   subprograms having unconstrained array formal parameters */

static tree
emit_index_check (tree gnu_array_object,
                  tree gnu_expr,
                  tree gnu_low,
                  tree gnu_high)
{
  tree gnu_expr_check;

  /* Checked expressions must be evaluated only once. */
  gnu_expr = protect_multiple_eval (gnu_expr);

  /* Must do this computation in the base type in case the expression's
     type is an unsigned subtypes.  */
  gnu_expr_check = convert (get_base_type (TREE_TYPE (gnu_expr)), gnu_expr);

  /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
     the object we are handling. */
  gnu_low = SUBSTITUTE_PLACEHOLDER_IN_EXPR (gnu_low, gnu_array_object);
  gnu_high = SUBSTITUTE_PLACEHOLDER_IN_EXPR (gnu_high, gnu_array_object);

  /* There's no good type to use here, so we might as well use
     integer_type_node.   */
  return emit_check
    (build_binary_op (TRUTH_ORIF_EXPR, integer_type_node,
                      build_binary_op (LT_EXPR, integer_type_node,
                                       gnu_expr_check,
                                       convert (TREE_TYPE (gnu_expr_check),
                                                gnu_low)),
                      build_binary_op (GT_EXPR, integer_type_node,
                                       gnu_expr_check,
                                       convert (TREE_TYPE (gnu_expr_check),
                                                gnu_high))),
     gnu_expr, CE_Index_Check_Failed);
}
\f
/* GNU_COND contains the condition corresponding to an access, discriminant or
   range check of value GNU_EXPR.  Build a COND_EXPR that returns GNU_EXPR if
   GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
   REASON is the code that says why the exception was raised.  */

static tree
emit_check (tree gnu_cond, tree gnu_expr, int reason)
{
  tree gnu_call;
  tree gnu_result;

  gnu_call = build_call_raise (reason, Empty, N_Raise_Constraint_Error);

  /* Use an outer COMPOUND_EXPR to make sure that GNU_EXPR will get evaluated
     in front of the comparison in case it ends up being a SAVE_EXPR.  Put the
     whole thing inside its own SAVE_EXPR so the inner SAVE_EXPR doesn't leak
     out.  */
  gnu_result = fold_build3 (COND_EXPR, TREE_TYPE (gnu_expr), gnu_cond,
                            build2 (COMPOUND_EXPR, TREE_TYPE (gnu_expr),
                                    gnu_call, gnu_expr),
                            gnu_expr);

  /* If GNU_EXPR has side effects, make the outer COMPOUND_EXPR and
     protect it.  Otherwise, show GNU_RESULT has no side effects: we
     don't need to evaluate it just for the check.  */
  if (TREE_SIDE_EFFECTS (gnu_expr))
    gnu_result
      = build2 (COMPOUND_EXPR, TREE_TYPE (gnu_expr), gnu_expr, gnu_result);
  else
    TREE_SIDE_EFFECTS (gnu_result) = 0;

  /* ??? Unfortunately, if we don't put a SAVE_EXPR around this whole thing,
     we will repeatedly do the test.  It would be nice if GCC was able
     to optimize this and only do it once.  */
  return save_expr (gnu_result);
}
\f
/* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing
   overflow checks if OVERFLOW_P is nonzero and range checks if
   RANGE_P is nonzero.  GNAT_TYPE is known to be an integral type.
   If TRUNCATE_P is nonzero, do a float to integer conversion with
   truncation; otherwise round.  */

static tree
convert_with_check (Entity_Id gnat_type, tree gnu_expr, bool overflowp,
                    bool rangep, bool truncatep)
{
  tree gnu_type = get_unpadded_type (gnat_type);
  tree gnu_in_type = TREE_TYPE (gnu_expr);
  tree gnu_in_basetype = get_base_type (gnu_in_type);
  tree gnu_base_type = get_base_type (gnu_type);
  tree gnu_result = gnu_expr;

  /* If we are not doing any checks, the output is an integral type, and
     the input is not a floating type, just do the conversion.  This
     shortcut is required to avoid problems with packed array types
     and simplifies code in all cases anyway.   */
  if (!rangep && !overflowp && INTEGRAL_TYPE_P (gnu_base_type)
      && !FLOAT_TYPE_P (gnu_in_type))
    return convert (gnu_type, gnu_expr);

  /* First convert the expression to its base type.  This
     will never generate code, but makes the tests below much simpler.
     But don't do this if converting from an integer type to an unconstrained
     array type since then we need to get the bounds from the original
     (unpacked) type.  */
  if (TREE_CODE (gnu_type) != UNCONSTRAINED_ARRAY_TYPE)
    gnu_result = convert (gnu_in_basetype, gnu_result);

  /* If overflow checks are requested,  we need to be sure the result will
     fit in the output base type.  But don't do this if the input
     is integer and the output floating-point.  */
  if (overflowp
      && !(FLOAT_TYPE_P (gnu_base_type) && INTEGRAL_TYPE_P (gnu_in_basetype)))
    {
      /* Ensure GNU_EXPR only gets evaluated once.  */
      tree gnu_input = protect_multiple_eval (gnu_result);
      tree gnu_cond = integer_zero_node;
      tree gnu_in_lb = TYPE_MIN_VALUE (gnu_in_basetype);
      tree gnu_in_ub = TYPE_MAX_VALUE (gnu_in_basetype);
      tree gnu_out_lb = TYPE_MIN_VALUE (gnu_base_type);
      tree gnu_out_ub = TYPE_MAX_VALUE (gnu_base_type);

      /* Convert the lower bounds to signed types, so we're sure we're
         comparing them properly.  Likewise, convert the upper bounds
         to unsigned types.  */
      if (INTEGRAL_TYPE_P (gnu_in_basetype) && TYPE_UNSIGNED (gnu_in_basetype))
        gnu_in_lb = convert (gnat_signed_type (gnu_in_basetype), gnu_in_lb);

      if (INTEGRAL_TYPE_P (gnu_in_basetype)
          && !TYPE_UNSIGNED (gnu_in_basetype))
        gnu_in_ub = convert (gnat_unsigned_type (gnu_in_basetype), gnu_in_ub);

      if (INTEGRAL_TYPE_P (gnu_base_type) && TYPE_UNSIGNED (gnu_base_type))
        gnu_out_lb = convert (gnat_signed_type (gnu_base_type), gnu_out_lb);

      if (INTEGRAL_TYPE_P (gnu_base_type) && !TYPE_UNSIGNED (gnu_base_type))
        gnu_out_ub = convert (gnat_unsigned_type (gnu_base_type), gnu_out_ub);

      /* Check each bound separately and only if the result bound
         is tighter than the bound on the input type.  Note that all the
         types are base types, so the bounds must be constant. Also,
         the comparison is done in the base type of the input, which
         always has the proper signedness.  First check for input
         integer (which means output integer), output float (which means
         both float), or mixed, in which case we always compare.
         Note that we have to do the comparison which would *fail* in the
         case of an error since if it's an FP comparison and one of the
         values is a NaN or Inf, the comparison will fail.  */
      if (INTEGRAL_TYPE_P (gnu_in_basetype)
          ? tree_int_cst_lt (gnu_in_lb, gnu_out_lb)
          : (FLOAT_TYPE_P (gnu_base_type)
             ? REAL_VALUES_LESS (TREE_REAL_CST (gnu_in_lb),
                                 TREE_REAL_CST (gnu_out_lb))
             : 1))
        gnu_cond
          = invert_truthvalue
            (build_binary_op (GE_EXPR, integer_type_node,
                              gnu_input, convert (gnu_in_basetype,
                                                  gnu_out_lb)));

      if (INTEGRAL_TYPE_P (gnu_in_basetype)
          ? tree_int_cst_lt (gnu_out_ub, gnu_in_ub)
          : (FLOAT_TYPE_P (gnu_base_type)
             ? REAL_VALUES_LESS (TREE_REAL_CST (gnu_out_ub),
                                 TREE_REAL_CST (gnu_in_lb))
             : 1))
        gnu_cond
          = build_binary_op (TRUTH_ORIF_EXPR, integer_type_node, gnu_cond,
                             invert_truthvalue
                             (build_binary_op (LE_EXPR, integer_type_node,
                                               gnu_input,
                                               convert (gnu_in_basetype,
                                                        gnu_out_ub))));

      if (!integer_zerop (gnu_cond))
        gnu_result = emit_check (gnu_cond, gnu_input,
                                 CE_Overflow_Check_Failed);
    }

  /* Now convert to the result base type.  If this is a non-truncating
     float-to-integer conversion, round.  */
  if (INTEGRAL_TYPE_P (gnu_base_type) && FLOAT_TYPE_P (gnu_in_basetype)
      && !truncatep)
    {
      REAL_VALUE_TYPE half_minus_pred_half, pred_half;
      tree gnu_conv, gnu_zero, gnu_comp, gnu_saved_result, calc_type;
      tree gnu_pred_half, gnu_add_pred_half, gnu_subtract_pred_half;
      const struct real_format *fmt;

      /* The following calculations depend on proper rounding to even
         of each arithmetic operation. In order to prevent excess
         precision from spoiling this property, use the widest hardware
         floating-point type.

         FIXME: For maximum efficiency, this should only be done for machines
         and types where intermediates may have extra precision.  */

      calc_type = longest_float_type_node;
      /* FIXME: Should not have padding in the first place */
      if (TREE_CODE (calc_type) == RECORD_TYPE
              && TYPE_IS_PADDING_P (calc_type))
        calc_type = TREE_TYPE (TYPE_FIELDS (calc_type));

      /* Compute the exact value calc_type'Pred (0.5) at compile time. */
      fmt = REAL_MODE_FORMAT (TYPE_MODE (calc_type));
      real_2expN (&half_minus_pred_half, -(fmt->p) - 1, TYPE_MODE (calc_type));
      REAL_ARITHMETIC (pred_half, MINUS_EXPR, dconsthalf,
                       half_minus_pred_half);
      gnu_pred_half = build_real (calc_type, pred_half);

      /* If the input is strictly negative, subtract this value
         and otherwise add it from the input. For 0.5, the result
         is exactly between 1.0 and the machine number preceding 1.0
         (for calc_type). Since the last bit of 1.0 is even, this 0.5
         will round to 1.0, while all other number with an absolute
         value less than 0.5 round to 0.0. For larger numbers exactly
         halfway between integers, rounding will always be correct as
         the true mathematical result will be closer to the higher
         integer compared to the lower one. So, this constant works
         for all floating-point numbers.

         The reason to use the same constant with subtract/add instead
         of a positive and negative constant is to allow the comparison
         to be scheduled in parallel with retrieval of the constant and
         conversion of the input to the calc_type (if necessary).
      */

      gnu_zero = convert (gnu_in_basetype, integer_zero_node);
      gnu_saved_result = save_expr (gnu_result);
      gnu_conv = convert (calc_type, gnu_saved_result);
      gnu_comp = build2 (GE_EXPR, integer_type_node,
                        gnu_saved_result, gnu_zero);
      gnu_add_pred_half
        = build2 (PLUS_EXPR, calc_type, gnu_conv, gnu_pred_half);
      gnu_subtract_pred_half
        = build2 (MINUS_EXPR, calc_type, gnu_conv, gnu_pred_half);
      gnu_result = build3 (COND_EXPR, calc_type, gnu_comp,
                           gnu_add_pred_half, gnu_subtract_pred_half);
    }

  if (TREE_CODE (gnu_base_type) == INTEGER_TYPE
      && TYPE_HAS_ACTUAL_BOUNDS_P (gnu_base_type)
      && TREE_CODE (gnu_result) == UNCONSTRAINED_ARRAY_REF)
    gnu_result = unchecked_convert (gnu_base_type, gnu_result, false);
  else
    gnu_result = convert (gnu_base_type, gnu_result);

  /* Finally, do the range check if requested.  Note that if the
     result type is a modular type, the range check is actually
     an overflow check.  */

  if (rangep
      || (TREE_CODE (gnu_base_type) == INTEGER_TYPE
          && TYPE_MODULAR_P (gnu_base_type) && overflowp))
    gnu_result = emit_range_check (gnu_result, gnat_type);

  return convert (gnu_type, gnu_result);
}
\f
/* Return true if TYPE is a smaller packable version of RECORD_TYPE.  */

static bool
smaller_packable_type_p (tree type, tree record_type)
{
  tree size, rsize;

  /* We're not interested in variants here.  */
  if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (record_type))
    return false;

  /* Like a variant, a packable version keeps the original TYPE_NAME.  */
  if (TYPE_NAME (type) != TYPE_NAME (record_type))
    return false;

  size = TYPE_SIZE (type);
  rsize = TYPE_SIZE (record_type);

  if (!(TREE_CODE (size) == INTEGER_CST && TREE_CODE (rsize) == INTEGER_CST))
    return false;

  return tree_int_cst_lt (size, rsize) != 0;
}

/* Return true if GNU_EXPR can be directly addressed.  This is the case
   unless it is an expression involving computation or if it involves a
   reference to a bitfield or to an object not sufficiently aligned for
   its type.  If GNU_TYPE is non-null, return true only if GNU_EXPR can
   be directly addressed as an object of this type.

   *** Notes on addressability issues in the Ada compiler ***

   This predicate is necessary in order to bridge the gap between Gigi
   and the middle-end about addressability of GENERIC trees.  A tree
   is said to be addressable if it can be directly addressed, i.e. if
   its address can be taken, is a multiple of the type's alignment on
   strict-alignment architectures and returns the first storage unit
   assigned to the object represented by the tree.

   In the C family of languages, everything is in practice addressable
   at the language level, except for bit-fields.  This means that these
   compilers will take the address of any tree that doesn't represent
   a bit-field reference and expect the result to be the first storage
   unit assigned to the object.  Even in cases where this will result
   in unaligned accesses at run time, nothing is supposed to be done
   and the program is considered as erroneous instead (see PR c/18287).

   The implicit assumptions made in the middle-end are in keeping with
   the C viewpoint described above:
     - the address of a bit-field reference is supposed to be never
       taken; the compiler (generally) will stop on such a construct,
     - any other tree is addressable if it is formally addressable,
       i.e. if it is formally allowed to be the operand of ADDR_EXPR.

   In Ada, the viewpoint is the opposite one: nothing is addressable
   at the language level unless explicitly declared so.  This means
   that the compiler will both make sure that the trees representing
   references to addressable ("aliased" in Ada parlance) objects are
   addressable and make no real attempts at ensuring that the trees
   representing references to non-addressable objects are addressable.

   In the first case, Ada is effectively equivalent to C and handing
   down the direct result of applying ADDR_EXPR to these trees to the
   middle-end works flawlessly.  In the second case, Ada cannot afford
   to consider the program as erroneous if the address of trees that
   are not addressable is requested for technical reasons, unlike C;
   as a consequence, the Ada compiler must arrange for either making
   sure that this address is not requested in the middle-end or for
   compensating by inserting temporaries if it is requested in Gigi.

   The first goal can be achieved because the middle-end should not
   request the address of non-addressable trees on its own; the only
   exception is for the invocation of low-level block operations like
   memcpy, for which the addressability requirements are lower since
   the type's alignment can be disregarded.  In practice, this means
   that Gigi must make sure that such operations cannot be applied to
   non-BLKmode bit-fields.

   The second goal is achieved by means of the addressable_p predicate
   and by inserting SAVE_EXPRs around trees deemed non-addressable.
   They will be turned during gimplification into proper temporaries
   whose address will be used in lieu of that of the original tree.  */

static bool
addressable_p (tree gnu_expr, tree gnu_type)
{
  /* The size of the real type of the object must not be smaller than
     that of the expected type, otherwise an indirect access in the
     latter type would be larger than the object.  Only records need
     to be considered in practice.  */
  if (gnu_type
      && TREE_CODE (gnu_type) == RECORD_TYPE
      && smaller_packable_type_p (TREE_TYPE (gnu_expr), gnu_type))
    return false;

  switch (TREE_CODE (gnu_expr))
    {
    case VAR_DECL:
    case PARM_DECL:
    case FUNCTION_DECL:
    case RESULT_DECL:
      /* All DECLs are addressable: if they are in a register, we can force
         them to memory.  */
      return true;

    case UNCONSTRAINED_ARRAY_REF:
    case INDIRECT_REF:
    case CONSTRUCTOR:
    case STRING_CST:
    case INTEGER_CST:
    case NULL_EXPR:
    case SAVE_EXPR:
    case CALL_EXPR:
      return true;

    case COND_EXPR:
      /* We accept &COND_EXPR as soon as both operands are addressable and
         expect the outcome to be the address of the selected operand.  */
      return (addressable_p (TREE_OPERAND (gnu_expr, 1), NULL_TREE)
              && addressable_p (TREE_OPERAND (gnu_expr, 2), NULL_TREE));

    case COMPONENT_REF:
      return (((!DECL_BIT_FIELD (TREE_OPERAND (gnu_expr, 1))
                /* Even with DECL_BIT_FIELD cleared, we have to ensure that
                   the field is sufficiently aligned, in case it is subject
                   to a pragma Component_Alignment.  But we don't need to
                   check the alignment of the containing record, as it is
                   guaranteed to be not smaller than that of its most
                   aligned field that is not a bit-field.  */
                && (!STRICT_ALIGNMENT
                    || DECL_ALIGN (TREE_OPERAND (gnu_expr, 1))
                       >= TYPE_ALIGN (TREE_TYPE (gnu_expr))))
               /* The field of a padding record is always addressable.  */
               || TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_expr, 0))))
              && addressable_p (TREE_OPERAND (gnu_expr, 0), NULL_TREE));

    case ARRAY_REF:  case ARRAY_RANGE_REF:
    case REALPART_EXPR:  case IMAGPART_EXPR:
    case NOP_EXPR:
      return addressable_p (TREE_OPERAND (gnu_expr, 0), NULL_TREE);

    case CONVERT_EXPR:
      return (AGGREGATE_TYPE_P (TREE_TYPE (gnu_expr))
              && addressable_p (TREE_OPERAND (gnu_expr, 0), NULL_TREE));

    case VIEW_CONVERT_EXPR:
      {
        /* This is addressable if we can avoid a copy.  */
        tree type = TREE_TYPE (gnu_expr);
        tree inner_type = TREE_TYPE (TREE_OPERAND (gnu_expr, 0));
        return (((TYPE_MODE (type) == TYPE_MODE (inner_type)
                  && (!STRICT_ALIGNMENT
                      || TYPE_ALIGN (type) <= TYPE_ALIGN (inner_type)
                      || TYPE_ALIGN (inner_type) >= BIGGEST_ALIGNMENT))
                 || ((TYPE_MODE (type) == BLKmode
                      || TYPE_MODE (inner_type) == BLKmode)
                     && (!STRICT_ALIGNMENT
                         || TYPE_ALIGN (type) <= TYPE_ALIGN (inner_type)
                         || TYPE_ALIGN (inner_type) >= BIGGEST_ALIGNMENT
                         || TYPE_ALIGN_OK (type)
                         || TYPE_ALIGN_OK (inner_type))))
                && addressable_p (TREE_OPERAND (gnu_expr, 0), NULL_TREE));
      }

    default:
      return false;
    }
}
\f
/* Do the processing for the declaration of a GNAT_ENTITY, a type.  If
   a separate Freeze node exists, delay the bulk of the processing.  Otherwise
   make a GCC type for GNAT_ENTITY and set up the correspondence.  */

void
process_type (Entity_Id gnat_entity)
{
  tree gnu_old
    = present_gnu_tree (gnat_entity) ? get_gnu_tree (gnat_entity) : 0;
  tree gnu_new;

  /* If we are to delay elaboration of this type, just do any
     elaborations needed for expressions within the declaration and
     make a dummy type entry for this node and its Full_View (if
     any) in case something points to it.  Don't do this if it
     has already been done (the only way that can happen is if
     the private completion is also delayed).  */
  if (Present (Freeze_Node (gnat_entity))
      || (IN (Ekind (gnat_entity), Incomplete_Or_Private_Kind)
          && Present (Full_View (gnat_entity))
          && Freeze_Node (Full_View (gnat_entity))
          && !present_gnu_tree (Full_View (gnat_entity))))
    {
      elaborate_entity (gnat_entity);

      if (!gnu_old)
        {
          tree gnu_decl = create_type_decl (get_entity_name (gnat_entity),
                                            make_dummy_type (gnat_entity),
                                            NULL, false, false, gnat_entity);

          save_gnu_tree (gnat_entity, gnu_decl, false);
          if (IN (Ekind (gnat_entity), Incomplete_Or_Private_Kind)
              && Present (Full_View (gnat_entity)))
            save_gnu_tree (Full_View (gnat_entity), gnu_decl, false);
        }

      return;
    }

  /* If we saved away a dummy type for this node it means that this
     made the type that corresponds to the full type of an incomplete
     type.  Clear that type for now and then update the type in the
     pointers.  */
  if (gnu_old)
    {
      gcc_assert (TREE_CODE (gnu_old) == TYPE_DECL
                  && TYPE_IS_DUMMY_P (TREE_TYPE (gnu_old)));

      save_gnu_tree (gnat_entity, NULL_TREE, false);
    }

  /* Now fully elaborate the type.  */
  gnu_new = gnat_to_gnu_entity (gnat_entity, NULL_TREE, 1);
  gcc_assert (TREE_CODE (gnu_new) == TYPE_DECL);

  /* If we have an old type and we've made pointers to this type,
     update those pointers.  */
  if (gnu_old)
    update_pointer_to (TYPE_MAIN_VARIANT (TREE_TYPE (gnu_old)),
                       TREE_TYPE (gnu_new));

  /* If this is a record type corresponding to a task or protected type
     that is a completion of an incomplete type, perform a similar update
     on the type.  */
  /* ??? Including protected types here is a guess. */

  if (IN (Ekind (gnat_entity), Record_Kind)
      && Is_Concurrent_Record_Type (gnat_entity)
      && present_gnu_tree (Corresponding_Concurrent_Type (gnat_entity)))
    {
      tree gnu_task_old
        = get_gnu_tree (Corresponding_Concurrent_Type (gnat_entity));

      save_gnu_tree (Corresponding_Concurrent_Type (gnat_entity),
                     NULL_TREE, false);
      save_gnu_tree (Corresponding_Concurrent_Type (gnat_entity),
                     gnu_new, false);

      update_pointer_to (TYPE_MAIN_VARIANT (TREE_TYPE (gnu_task_old)),
                         TREE_TYPE (gnu_new));
    }
}
\f
/* GNAT_ENTITY is the type of the resulting constructors,
   GNAT_ASSOC is the front of the Component_Associations of an N_Aggregate,
   and GNU_TYPE is the GCC type of the corresponding record.

   Return a CONSTRUCTOR to build the record.  */

static tree
assoc_to_constructor (Entity_Id gnat_entity, Node_Id gnat_assoc, tree gnu_type)
{
  tree gnu_list, gnu_result;

  /* We test for GNU_FIELD being empty in the case where a variant
     was the last thing since we don't take things off GNAT_ASSOC in
     that case.  We check GNAT_ASSOC in case we have a variant, but it
     has no fields.  */

  for (gnu_list = NULL_TREE; Present (gnat_assoc);
       gnat_assoc = Next (gnat_assoc))
    {
      Node_Id gnat_field = First (Choices (gnat_assoc));
      tree gnu_field = gnat_to_gnu_field_decl (Entity (gnat_field));
      tree gnu_expr = gnat_to_gnu (Expression (gnat_assoc));

      /* The expander is supposed to put a single component selector name
         in every record component association */
      gcc_assert (No (Next (gnat_field)));

      /* Ignore fields that have Corresponding_Discriminants since we'll
         be setting that field in the parent.  */
      if (Present (Corresponding_Discriminant (Entity (gnat_field)))
          && Is_Tagged_Type (Scope (Entity (gnat_field))))
        continue;

      /* Also ignore discriminants of Unchecked_Unions.  */
      else if (Is_Unchecked_Union (gnat_entity)
               && Ekind (Entity (gnat_field)) == E_Discriminant)
        continue;

      /* Before assigning a value in an aggregate make sure range checks
         are done if required.  Then convert to the type of the field.  */
      if (Do_Range_Check (Expression (gnat_assoc)))
        gnu_expr = emit_range_check (gnu_expr, Etype (gnat_field));

      gnu_expr = convert (TREE_TYPE (gnu_field), gnu_expr);

      /* Add the field and expression to the list.  */
      gnu_list = tree_cons (gnu_field, gnu_expr, gnu_list);
    }

  gnu_result = extract_values (gnu_list, gnu_type);

#ifdef ENABLE_CHECKING
  {
    tree gnu_field;

    /* Verify every entry in GNU_LIST was used.  */
    for (gnu_field = gnu_list; gnu_field; gnu_field = TREE_CHAIN (gnu_field))
      gcc_assert (TREE_ADDRESSABLE (gnu_field));
  }
#endif

  return gnu_result;
}

/* Builds a possibly nested constructor for array aggregates. GNAT_EXPR
   is the first element of an array aggregate. It may itself be an
   aggregate (an array or record aggregate). GNU_ARRAY_TYPE is the gnu type
   corresponding to the array aggregate. GNAT_COMPONENT_TYPE is the type
   of the array component. It is needed for range checking. */

static tree
pos_to_constructor (Node_Id gnat_expr, tree gnu_array_type,
                    Entity_Id gnat_component_type)
{
  tree gnu_expr_list = NULL_TREE;
  tree gnu_index = TYPE_MIN_VALUE (TYPE_DOMAIN (gnu_array_type));
  tree gnu_expr;

  for ( ; Present (gnat_expr); gnat_expr = Next (gnat_expr))
    {
      /* If the expression is itself an array aggregate then first build the
         innermost constructor if it is part of our array (multi-dimensional
         case).  */

      if (Nkind (gnat_expr) == N_Aggregate
          && TREE_CODE (TREE_TYPE (gnu_array_type)) == ARRAY_TYPE
          && TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_array_type)))
        gnu_expr = pos_to_constructor (First (Expressions (gnat_expr)),
                                       TREE_TYPE (gnu_array_type),
                                       gnat_component_type);
      else
        {
          gnu_expr = gnat_to_gnu (gnat_expr);

          /* before assigning the element to the array make sure it is
             in range */
          if (Do_Range_Check (gnat_expr))
            gnu_expr = emit_range_check (gnu_expr, gnat_component_type);
        }

      gnu_expr_list
        = tree_cons (gnu_index, convert (TREE_TYPE (gnu_array_type), gnu_expr),
                     gnu_expr_list);

      gnu_index = int_const_binop (PLUS_EXPR, gnu_index, integer_one_node, 0);
    }

  return gnat_build_constructor (gnu_array_type, nreverse (gnu_expr_list));
}
\f
/* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
   some of which are from RECORD_TYPE.  Return a CONSTRUCTOR consisting
   of the associations that are from RECORD_TYPE.  If we see an internal
   record, make a recursive call to fill it in as well.  */

static tree
extract_values (tree values, tree record_type)
{
  tree result = NULL_TREE;
  tree field, tem;

  for (field = TYPE_FIELDS (record_type); field; field = TREE_CHAIN (field))
    {
      tree value = 0;

      /* _Parent is an internal field, but may have values in the aggregate,
         so check for values first.  */
      if ((tem = purpose_member (field, values)))
        {
          value = TREE_VALUE (tem);
          TREE_ADDRESSABLE (tem) = 1;
        }

      else if (DECL_INTERNAL_P (field))
        {
          value = extract_values (values, TREE_TYPE (field));
          if (TREE_CODE (value) == CONSTRUCTOR
              && VEC_empty (constructor_elt, CONSTRUCTOR_ELTS (value)))
            value = 0;
        }
      else
        /* If we have a record subtype, the names will match, but not the
           actual FIELD_DECLs.  */
        for (tem = values; tem; tem = TREE_CHAIN (tem))
          if (DECL_NAME (TREE_PURPOSE (tem)) == DECL_NAME (field))
            {
              value = convert (TREE_TYPE (field), TREE_VALUE (tem));
              TREE_ADDRESSABLE (tem) = 1;
            }

      if (!value)
        continue;

      result = tree_cons (field, value, result);
    }

  return gnat_build_constructor (record_type, nreverse (result));
}
\f
/* EXP is to be treated as an array or record.  Handle the cases when it is
   an access object and perform the required dereferences.  */

static tree
maybe_implicit_deref (tree exp)
{
  /* If the type is a pointer, dereference it.  */

  if (POINTER_TYPE_P (TREE_TYPE (exp)) || TYPE_FAT_POINTER_P (TREE_TYPE (exp)))
    exp = build_unary_op (INDIRECT_REF, NULL_TREE, exp);

  /* If we got a padded type, remove it too.  */
  if (TREE_CODE (TREE_TYPE (exp)) == RECORD_TYPE
      && TYPE_IS_PADDING_P (TREE_TYPE (exp)))
    exp = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (exp))), exp);

  return exp;
}
\f
/* Protect EXP from multiple evaluation.  This may make a SAVE_EXPR.  */

tree
protect_multiple_eval (tree exp)
{
  tree type = TREE_TYPE (exp);

  /* If this has no side effects, we don't need to do anything.  */
  if (!TREE_SIDE_EFFECTS (exp))
    return exp;

  /* If it is a conversion, protect what's inside the conversion.
     Similarly, if we're indirectly referencing something, we only
     actually need to protect the address since the data itself can't
     change in these situations.  */
  else if (TREE_CODE (exp) == NON_LVALUE_EXPR
           || CONVERT_EXPR_P (exp)
           || TREE_CODE (exp) == VIEW_CONVERT_EXPR
           || TREE_CODE (exp) == INDIRECT_REF
           || TREE_CODE (exp) == UNCONSTRAINED_ARRAY_REF)
    return build1 (TREE_CODE (exp), type,
                   protect_multiple_eval (TREE_OPERAND (exp, 0)));

  /* If EXP is a fat pointer or something that can be placed into a register,
     just make a SAVE_EXPR.  */
  if (TYPE_FAT_POINTER_P (type) || TYPE_MODE (type) != BLKmode)
    return save_expr (exp);

  /* Otherwise, dereference, protect the address, and re-reference.  */
  else
    return
      build_unary_op (INDIRECT_REF, type,
                      save_expr (build_unary_op (ADDR_EXPR,
                                                 build_reference_type (type),
                                                 exp)));
}
\f
/* This is equivalent to stabilize_reference in tree.c, but we know how to
   handle our own nodes and we take extra arguments.  FORCE says whether to
   force evaluation of everything.  We set SUCCESS to true unless we walk
   through something we don't know how to stabilize.  */

tree
maybe_stabilize_reference (tree ref, bool force, bool *success)
{
  tree type = TREE_TYPE (ref);
  enum tree_code code = TREE_CODE (ref);
  tree result;

  /* Assume we'll success unless proven otherwise.  */
  *success = true;

  switch (code)
    {
    case CONST_DECL:
    case VAR_DECL:
    case PARM_DECL:
    case RESULT_DECL:
      /* No action is needed in this case.  */
      return ref;

    case ADDR_EXPR:
    CASE_CONVERT:
    case FLOAT_EXPR:
    case FIX_TRUNC_EXPR:
    case VIEW_CONVERT_EXPR:
      result
        = build1 (code, type,
                  maybe_stabilize_reference (TREE_OPERAND (ref, 0), force,
                                             success));
      break;

    case INDIRECT_REF:
    case UNCONSTRAINED_ARRAY_REF:
      result = build1 (code, type,
                       gnat_stabilize_reference_1 (TREE_OPERAND (ref, 0),
                                                   force));
      break;

    case COMPONENT_REF:
     result = build3 (COMPONENT_REF, type,
                      maybe_stabilize_reference (TREE_OPERAND (ref, 0), force,
                                                 success),
                      TREE_OPERAND (ref, 1), NULL_TREE);
      break;

    case BIT_FIELD_REF:
      result = build3 (BIT_FIELD_REF, type,
                       maybe_stabilize_reference (TREE_OPERAND (ref, 0), force,
                                                  success),
                       gnat_stabilize_reference_1 (TREE_OPERAND (ref, 1),
                                                   force),
                       gnat_stabilize_reference_1 (TREE_OPERAND (ref, 2),
                                                   force));
      break;

    case ARRAY_REF:
    case ARRAY_RANGE_REF:
      result = build4 (code, type,
                       maybe_stabilize_reference (TREE_OPERAND (ref, 0), force,
                                                  success),
                       gnat_stabilize_reference_1 (TREE_OPERAND (ref, 1),
                                                   force),
                       NULL_TREE, NULL_TREE);
      break;

    case COMPOUND_EXPR:
      result = gnat_stabilize_reference_1 (ref, force);
      break;

    case CALL_EXPR:
      /* This generates better code than the scheme in protect_multiple_eval
         because large objects will be returned via invisible reference in
         most ABIs so the temporary will directly be filled by the callee.  */
      result = gnat_stabilize_reference_1 (ref, force);
      break;

    case CONSTRUCTOR:
      /* Constructors with 1 element are used extensively to formally
         convert objects to special wrapping types.  */
      if (TREE_CODE (type) == RECORD_TYPE
          && VEC_length (constructor_elt, CONSTRUCTOR_ELTS (ref)) == 1)
        {
          tree index
            = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (ref), 0)->index;
          tree value
            = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (ref), 0)->value;
          result
            = build_constructor_single (type, index,
                                        gnat_stabilize_reference_1 (value,
                                                                    force));
        }
      else
        {
          *success = false;
          return ref;
        }
      break;

    case ERROR_MARK:
      ref = error_mark_node;

      /* ...  Fallthru to failure ... */

      /* If arg isn't a kind of lvalue we recognize, make no change.
         Caller should recognize the error for an invalid lvalue.  */
    default:
      *success = false;
      return ref;
    }

  TREE_READONLY (result) = TREE_READONLY (ref);

  /* TREE_THIS_VOLATILE and TREE_SIDE_EFFECTS attached to the initial
     expression may not be sustained across some paths, such as the way via
     build1 for INDIRECT_REF.  We re-populate those flags here for the general
     case, which is consistent with the GCC version of this routine.

     Special care should be taken regarding TREE_SIDE_EFFECTS, because some
     paths introduce side effects where there was none initially (e.g. calls
     to save_expr), and we also want to keep track of that.  */

  TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (ref);
  TREE_SIDE_EFFECTS (result) |= TREE_SIDE_EFFECTS (ref);

  return result;
}

/* Wrapper around maybe_stabilize_reference, for common uses without
   lvalue restrictions and without need to examine the success
   indication.  */

static tree
gnat_stabilize_reference (tree ref, bool force)
{
  bool dummy;
  return maybe_stabilize_reference (ref, force, &dummy);
}

/* Similar to stabilize_reference_1 in tree.c, but supports an extra
   arg to force a SAVE_EXPR for everything.  */

static tree
gnat_stabilize_reference_1 (tree e, bool force)
{
  enum tree_code code = TREE_CODE (e);
  tree type = TREE_TYPE (e);
  tree result;

  /* We cannot ignore const expressions because it might be a reference
     to a const array but whose index contains side-effects.  But we can
     ignore things that are actual constant or that already have been
     handled by this function.  */

  if (TREE_CONSTANT (e) || code == SAVE_EXPR)
    return e;

  switch (TREE_CODE_CLASS (code))
    {
    case tcc_exceptional:
    case tcc_type:
    case tcc_declaration:
    case tcc_comparison:
    case tcc_statement:
    case tcc_expression:
    case tcc_reference:
    case tcc_vl_exp:
      /* If this is a COMPONENT_REF of a fat pointer, save 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 (code == COMPONENT_REF
          && TYPE_FAT_POINTER_P (TREE_TYPE (TREE_OPERAND (e, 0))))
        result = build3 (COMPONENT_REF, type,
                         gnat_stabilize_reference_1 (TREE_OPERAND (e, 0),
                                                     force),
                         TREE_OPERAND (e, 1), TREE_OPERAND (e, 2));
      else if (TREE_SIDE_EFFECTS (e) || force)
        return save_expr (e);
      else
        return e;
      break;

    case tcc_constant:
      /* Constants need no processing.  In fact, we should never reach
         here.  */
      return e;

    case tcc_binary:
      /* Recursively stabilize each operand.  */
      result = build2 (code, type,
                       gnat_stabilize_reference_1 (TREE_OPERAND (e, 0), force),
                       gnat_stabilize_reference_1 (TREE_OPERAND (e, 1),
                                                   force));
      break;

    case tcc_unary:
      /* Recursively stabilize each operand.  */
      result = build1 (code, type,
                       gnat_stabilize_reference_1 (TREE_OPERAND (e, 0),
                                                   force));
      break;

    default:
      gcc_unreachable ();
    }

  TREE_READONLY (result) = TREE_READONLY (e);

  TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
  TREE_SIDE_EFFECTS (result) |= TREE_SIDE_EFFECTS (e);
  return result;
}
\f
/* Convert SLOC into LOCUS.  Return true if SLOC corresponds to a source code
   location and false if it doesn't.  In the former case, set the Gigi global
   variable REF_FILENAME to the simple debug file name as given by sinput.  */

bool
Sloc_to_locus (Source_Ptr Sloc, location_t *locus)
{
  if (Sloc == No_Location)
    return false;

  if (Sloc <= Standard_Location)
    {
      if (*locus == UNKNOWN_LOCATION)
        *locus = BUILTINS_LOCATION;
      return false;
    }
  else
    {
      Source_File_Index file = Get_Source_File_Index (Sloc);
      Logical_Line_Number line = Get_Logical_Line_Number (Sloc);
      Column_Number column = Get_Column_Number (Sloc);
      struct line_map *map = &line_table->maps[file - 1];

      /* Translate the location according to the line-map.h formula.  */
      *locus = map->start_location
                + ((line - map->to_line) << map->column_bits)
                + (column & ((1 << map->column_bits) - 1));
    }

  ref_filename
    = IDENTIFIER_POINTER
      (get_identifier
       (Get_Name_String (Debug_Source_Name (Get_Source_File_Index (Sloc)))));;

  return true;
}

/* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
   don't do anything if it doesn't correspond to a source location.  */

static void
set_expr_location_from_node (tree node, Node_Id gnat_node)
{
  location_t locus;

  if (!Sloc_to_locus (Sloc (gnat_node), &locus))
    return;

  set_expr_location (node, locus);
}
\f
/* Return a colon-separated list of encodings contained in encoded Ada
   name.  */

static const char *
extract_encoding (const char *name)
{
  char *encoding = GGC_NEWVEC (char, strlen (name));
  
  get_encoding (name, encoding);
  
  return encoding;
}

/* Extract the Ada name from an encoded name.  */

static const char *
decode_name (const char *name)
{
  char *decoded = GGC_NEWVEC (char, strlen (name) * 2 + 60);
  
  __gnat_decode (name, decoded, 0);
  
  return decoded;
}
\f
/* Post an error message.  MSG is the error message, properly annotated.
   NODE is the node at which to post the error and the node to use for the
   "&" substitution.  */

void
post_error (const char *msg, Node_Id node)
{
  String_Template temp;
  Fat_Pointer fp;

  temp.Low_Bound = 1, temp.High_Bound = strlen (msg);
  fp.Array = msg, fp.Bounds = &temp;
  if (Present (node))
    Error_Msg_N (fp, node);
}

/* Similar, but NODE is the node at which to post the error and ENT
   is the node to use for the "&" substitution.  */

void
post_error_ne (const char *msg, Node_Id node, Entity_Id ent)
{
  String_Template temp;
  Fat_Pointer fp;

  temp.Low_Bound = 1, temp.High_Bound = strlen (msg);
  fp.Array = msg, fp.Bounds = &temp;
  if (Present (node))
    Error_Msg_NE (fp, node, ent);
}

/* Similar, but NODE is the node at which to post the error, ENT is the node
   to use for the "&" substitution, and N is the number to use for the ^.  */

void
post_error_ne_num (const char *msg, Node_Id node, Entity_Id ent, int n)
{
  String_Template temp;
  Fat_Pointer fp;

  temp.Low_Bound = 1, temp.High_Bound = strlen (msg);
  fp.Array = msg, fp.Bounds = &temp;
  Error_Msg_Uint_1 = UI_From_Int (n);

  if (Present (node))
    Error_Msg_NE (fp, node, ent);
}
\f
/* Similar to post_error_ne_num, but T is a GCC tree representing the
   number to write.  If the tree represents a constant that fits within
   a host integer, the text inside curly brackets in MSG will be output
   (presumably including a '^').  Otherwise that text will not be output
   and the text inside square brackets will be output instead.  */

void
post_error_ne_tree (const char *msg, Node_Id node, Entity_Id ent, tree t)
{
  char *newmsg = XALLOCAVEC (char, strlen (msg) + 1);
  String_Template temp = {1, 0};
  Fat_Pointer fp;
  char start_yes, end_yes, start_no, end_no;
  const char *p;
  char *q;

  fp.Array = newmsg, fp.Bounds = &temp;

  if (host_integerp (t, 1)
#if HOST_BITS_PER_WIDE_INT > HOST_BITS_PER_INT
      &&
      compare_tree_int
      (t, (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_INT - 1)) - 1)) < 0
#endif
      )
    {
      Error_Msg_Uint_1 = UI_From_Int (tree_low_cst (t, 1));
      start_yes = '{', end_yes = '}', start_no = '[', end_no = ']';
    }
  else
    start_yes = '[', end_yes = ']', start_no = '{', end_no = '}';

  for (p = msg, q = newmsg; *p; p++)
    {
      if (*p == start_yes)
        for (p++; *p != end_yes; p++)
          *q++ = *p;
      else if (*p == start_no)
        for (p++; *p != end_no; p++)
          ;
      else
        *q++ = *p;
    }

  *q = 0;

  temp.High_Bound = strlen (newmsg);
  if (Present (node))
    Error_Msg_NE (fp, node, ent);
}

/* Similar to post_error_ne_tree, except that NUM is a second
   integer to write in the message.  */

void
post_error_ne_tree_2 (const char *msg,
                      Node_Id node,
                      Entity_Id ent,
                      tree t,
                      int num)
{
  Error_Msg_Uint_2 = UI_From_Int (num);
  post_error_ne_tree (msg, node, ent, t);
}
\f
/* Initialize the table that maps GNAT codes to GCC codes for simple
   binary and unary operations.  */

static void
init_code_table (void)
{
  gnu_codes[N_And_Then] = TRUTH_ANDIF_EXPR;
  gnu_codes[N_Or_Else] = TRUTH_ORIF_EXPR;

  gnu_codes[N_Op_And] = TRUTH_AND_EXPR;
  gnu_codes[N_Op_Or] = TRUTH_OR_EXPR;
  gnu_codes[N_Op_Xor] = TRUTH_XOR_EXPR;
  gnu_codes[N_Op_Eq] = EQ_EXPR;
  gnu_codes[N_Op_Ne] = NE_EXPR;
  gnu_codes[N_Op_Lt] = LT_EXPR;
  gnu_codes[N_Op_Le] = LE_EXPR;
  gnu_codes[N_Op_Gt] = GT_EXPR;
  gnu_codes[N_Op_Ge] = GE_EXPR;
  gnu_codes[N_Op_Add] = PLUS_EXPR;
  gnu_codes[N_Op_Subtract] = MINUS_EXPR;
  gnu_codes[N_Op_Multiply] = MULT_EXPR;
  gnu_codes[N_Op_Mod] = FLOOR_MOD_EXPR;
  gnu_codes[N_Op_Rem] = TRUNC_MOD_EXPR;
  gnu_codes[N_Op_Minus] = NEGATE_EXPR;
  gnu_codes[N_Op_Abs] = ABS_EXPR;
  gnu_codes[N_Op_Not] = TRUTH_NOT_EXPR;
  gnu_codes[N_Op_Rotate_Left] = LROTATE_EXPR;
  gnu_codes[N_Op_Rotate_Right] = RROTATE_EXPR;
  gnu_codes[N_Op_Shift_Left] = LSHIFT_EXPR;
  gnu_codes[N_Op_Shift_Right] = RSHIFT_EXPR;
  gnu_codes[N_Op_Shift_Right_Arithmetic] = RSHIFT_EXPR;
}

/* Return a label to branch to for the exception type in KIND or NULL_TREE
   if none.  */

tree
get_exception_label (char kind)
{
  if (kind == N_Raise_Constraint_Error)
    return TREE_VALUE (gnu_constraint_error_label_stack);
  else if (kind == N_Raise_Storage_Error)
    return TREE_VALUE (gnu_storage_error_label_stack);
  else if (kind == N_Raise_Program_Error)
    return TREE_VALUE (gnu_program_error_label_stack);
  else
    return NULL_TREE;
}

#include "gt-ada-trans.h"