path: root/gcc/ada/exp_imgv.adb

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                             E X P _ I M G V                              --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--                            $Revision$
--                                                                          --
--            Copyright (C) 2001 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,  59 Temple Place - Suite 330,  Boston, --
-- MA 02111-1307, USA.                                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
--                                                                          --
------------------------------------------------------------------------------

with Atree;    use Atree;
with Casing;   use Casing;
with Checks;   use Checks;
with Einfo;    use Einfo;
with Exp_Util; use Exp_Util;
with Namet;    use Namet;
with Nmake;    use Nmake;
with Nlists;   use Nlists;
with Opt;      use Opt;
with Rtsfind;  use Rtsfind;
with Sem_Res;  use Sem_Res;
with Sinfo;    use Sinfo;
with Snames;   use Snames;
with Stand;    use Stand;
with Stringt;  use Stringt;
with Tbuild;   use Tbuild;
with Ttypes;   use Ttypes;
with Uintp;    use Uintp;

package body Exp_Imgv is

   ------------------------------------
   -- Build_Enumeration_Image_Tables --
   ------------------------------------

   procedure Build_Enumeration_Image_Tables (E : Entity_Id; N : Node_Id) is
      Loc  : constant Source_Ptr := Sloc (E);
      Str  : String_Id;
      Ind  : List_Id;
      Lit  : Entity_Id;
      Nlit : Nat;
      Len  : Nat;
      Estr : Entity_Id;
      Eind : Entity_Id;
      Ityp : Node_Id;

   begin
      --  Nothing to do for other than a root enumeration type

      if E /= Root_Type (E) then
         return;

      --  Nothing to do if pragma Discard_Names applies

      elsif Discard_Names (E) then
         return;
      end if;

      --  Otherwise tables need constructing

      Start_String;
      Ind := New_List;
      Lit := First_Literal (E);
      Len := 1;
      Nlit := 0;

      loop
         Append_To (Ind,
           Make_Integer_Literal (Loc, UI_From_Int (Len)));

         exit when No (Lit);
         Nlit := Nlit + 1;

         Get_Unqualified_Decoded_Name_String (Chars (Lit));

         if Name_Buffer (1) /= ''' then
            Set_Casing (All_Upper_Case);
         end if;

         Store_String_Chars (Name_Buffer (1 .. Name_Len));
         Len := Len + Int (Name_Len);
         Next_Literal (Lit);
      end loop;

      if Len < Int (2 ** (8 - 1)) then
         Ityp := Standard_Integer_8;
      elsif Len < Int (2 ** (16 - 1)) then
         Ityp := Standard_Integer_16;
      else
         Ityp := Standard_Integer_32;
      end if;

      Str := End_String;

      Estr :=
        Make_Defining_Identifier (Loc,
          Chars => New_External_Name (Chars (E), 'S'));

      Eind :=
        Make_Defining_Identifier (Loc,
          Chars => New_External_Name (Chars (E), 'I'));

      Set_Lit_Strings (E, Estr);
      Set_Lit_Indexes (E, Eind);

      Insert_Actions (N,
        New_List (
          Make_Object_Declaration (Loc,
            Defining_Identifier => Estr,
            Constant_Present    => True,
            Object_Definition   =>
              New_Occurrence_Of (Standard_String, Loc),
            Expression          =>
              Make_String_Literal (Loc,
                Strval => Str)),

          Make_Object_Declaration (Loc,
            Defining_Identifier => Eind,
            Constant_Present    => True,

            Object_Definition =>
              Make_Constrained_Array_Definition (Loc,
                Discrete_Subtype_Definitions => New_List (
                  Make_Range (Loc,
                    Low_Bound  => Make_Integer_Literal (Loc, 0),
                    High_Bound => Make_Integer_Literal (Loc, Nlit))),
                Subtype_Indication => New_Occurrence_Of (Ityp, Loc)),

            Expression          =>
              Make_Aggregate (Loc,
                Expressions => Ind))),
        Suppress => All_Checks);

   end Build_Enumeration_Image_Tables;

   ----------------------------
   -- Expand_Image_Attribute --
   ----------------------------

   --  For all non-enumeration types, and for enumeration types declared
   --  in packages Standard or System, typ'Image (Val) expands into:

   --     Image_xx (tp (Expr) [, pm])

   --  The name xx and type conversion tp (Expr) (called tv below) depend on
   --  the root type of Expr. The argument pm is an extra type dependent
   --  parameter only used in some cases as follows:

   --    For types whose root type is Character
   --      xx = Character
   --      tv = Character (Expr)

   --    For types whose root type is Boolean
   --      xx = Boolean
   --      tv = Boolean (Expr)

   --    For signed integer types with size <= Integer'Size
   --      xx = Integer
   --      tv = Integer (Expr)

   --    For other signed integer types
   --      xx = Long_Long_Integer
   --      tv = Long_Long_Integer (Expr)

   --    For modular types with modulus <= System.Unsigned_Types.Unsigned
   --      xx = Unsigned
   --      tv = System.Unsigned_Types.Unsigned (Expr)

   --    For other modular integer types
   --      xx = Long_Long_Unsigned
   --      tv = System.Unsigned_Types.Long_Long_Unsigned (Expr)

   --    For types whose root type is Wide_Character
   --      xx = Wide_Character
   --      tv = Wide_Character (Expr)
   --      pm = Wide_Character_Encoding_Method

   --    For floating-point types
   --      xx = Floating_Point
   --      tv = Long_Long_Float (Expr)
   --      pm = typ'Digits

   --    For ordinary fixed-point types
   --      xx = Ordinary_Fixed_Point
   --      tv = Long_Long_Float (Expr)
   --      pm = typ'Aft

   --    For decimal fixed-point types with size = Integer'Size
   --      xx = Decimal
   --      tv = Integer (Expr)
   --      pm = typ'Scale

   --    For decimal fixed-point types with size > Integer'Size
   --      xx = Long_Long_Decimal
   --      tv = Long_Long_Integer (Expr)
   --      pm = typ'Scale

   --    Note: for the decimal fixed-point type cases, the conversion is
   --    done literally without scaling (i.e. the actual expression that
   --    is generated is Image_xx (tp?(Expr) [, pm])

   --  For enumeration types other than those declared packages Standard
   --  or System, typ'Image (X) expands into:

   --    Image_Enumeration_NN (typ'Pos (X), typS, typI'Address)

   --  where typS and typI are the entities constructed as described in
   --  the spec for the procedure Build_Enumeration_Image_Tables and NN
   --  is 32/16/8 depending on the element type of Lit_Indexes.

   procedure Expand_Image_Attribute (N : Node_Id) is
      Loc      : constant Source_Ptr := Sloc (N);
      Exprs    : constant List_Id    := Expressions (N);
      Pref     : constant Node_Id    := Prefix (N);
      Ptyp     : constant Entity_Id  := Entity (Pref);
      Rtyp     : constant Entity_Id  := Root_Type (Ptyp);
      Expr     : constant Node_Id    := Relocate_Node (First (Exprs));
      Imid     : RE_Id;
      Tent     : Entity_Id;
      Arglist  : List_Id;
      Func     : RE_Id;
      Ttyp     : Entity_Id;
      Func_Ent : Entity_Id;

   begin
      if Rtyp = Standard_Boolean then
         Imid := RE_Image_Boolean;
         Tent := Rtyp;

      elsif Rtyp = Standard_Character then
         Imid := RE_Image_Character;
         Tent := Rtyp;

      elsif Rtyp = Standard_Wide_Character then
         Imid := RE_Image_Wide_Character;
         Tent := Rtyp;

      elsif Is_Signed_Integer_Type (Rtyp) then
         if Esize (Rtyp) <= Esize (Standard_Integer) then
            Imid := RE_Image_Integer;
            Tent := Standard_Integer;
         else
            Imid := RE_Image_Long_Long_Integer;
            Tent := Standard_Long_Long_Integer;
         end if;

      elsif Is_Modular_Integer_Type (Rtyp) then
         if Modulus (Rtyp) <= Modulus (RTE (RE_Unsigned)) then
            Imid := RE_Image_Unsigned;
            Tent := RTE (RE_Unsigned);
         else
            Imid := RE_Image_Long_Long_Unsigned;
            Tent := RTE (RE_Long_Long_Unsigned);
         end if;

      elsif Is_Decimal_Fixed_Point_Type (Rtyp) then
         if UI_To_Int (Esize (Rtyp)) <= Standard_Integer_Size then
            Imid := RE_Image_Decimal;
            Tent := Standard_Integer;
         else
            Imid := RE_Image_Long_Long_Decimal;
            Tent := Standard_Long_Long_Integer;
         end if;

      elsif Is_Ordinary_Fixed_Point_Type (Rtyp) then
         Imid := RE_Image_Ordinary_Fixed_Point;
         Tent := Standard_Long_Long_Float;

      elsif Is_Floating_Point_Type (Rtyp) then
         Imid := RE_Image_Floating_Point;
         Tent := Standard_Long_Long_Float;

      --  Only other possibility is user defined enumeration type

      else
         if Discard_Names (First_Subtype (Ptyp))
           or else No (Lit_Strings (Root_Type (Ptyp)))
         then
            --  When pragma Discard_Names applies to the first subtype,
            --  then build (Pref'Pos)'Img.

            Rewrite (N,
              Make_Attribute_Reference (Loc,
                Prefix =>
                   Make_Attribute_Reference (Loc,
                     Prefix         => Pref,
                     Attribute_Name => Name_Pos,
                     Expressions    => New_List (Expr)),
                Attribute_Name =>
                  Name_Img));
            Analyze_And_Resolve (N, Standard_String);

         else
            --  Here we get the Image of an enumeration type

            Ttyp := Component_Type (Etype (Lit_Indexes (Rtyp)));

            if Ttyp = Standard_Integer_8 then
               Func := RE_Image_Enumeration_8;
            elsif Ttyp = Standard_Integer_16  then
               Func := RE_Image_Enumeration_16;
            else
               Func := RE_Image_Enumeration_32;
            end if;

            --  Apply a validity check, since it is a bit drastic to
            --  get a completely junk image value for an invalid value.

            if not Expr_Known_Valid (Expr) then
               Insert_Valid_Check (Expr);
            end if;

            Rewrite (N,
              Make_Function_Call (Loc,
                Name => New_Occurrence_Of (RTE (Func), Loc),
                Parameter_Associations => New_List (
                  Make_Attribute_Reference (Loc,
                    Attribute_Name => Name_Pos,
                    Prefix         => New_Occurrence_Of (Ptyp, Loc),
                    Expressions    => New_List (Expr)),
                  New_Occurrence_Of (Lit_Strings (Rtyp), Loc),
                  Make_Attribute_Reference (Loc,
                    Prefix => New_Occurrence_Of (Lit_Indexes (Rtyp), Loc),
                    Attribute_Name => Name_Address))));

            Analyze_And_Resolve (N, Standard_String);
         end if;

         return;
      end if;

      --  If we fall through, we have one of the cases that is handled by
      --  calling one of the System.Img_xx routines and Imid is set to the
      --  RE_Id for the function to be called.

      Func_Ent := RTE (Imid);

      --  If the function entity is empty, that means we have a case in
      --  no run time mode where the operation is not allowed, and an
      --  appropriate diagnostic has already been issued.

      if No (Func_Ent) then
         return;
      end if;

      --  Otherwise prepare arguments for run-time call

      Arglist := New_List (Convert_To (Tent, Relocate_Node (Expr)));

      --  For floating-point types, append Digits argument

      if Is_Floating_Point_Type (Rtyp) then
         Append_To (Arglist,
           Make_Attribute_Reference (Loc,
             Prefix         => New_Reference_To (Ptyp, Loc),
             Attribute_Name => Name_Digits));

      --  For ordinary fixed-point types, append Aft parameter

      elsif Is_Ordinary_Fixed_Point_Type (Rtyp) then
         Append_To (Arglist,
           Make_Attribute_Reference (Loc,
             Prefix         => New_Reference_To (Ptyp, Loc),
             Attribute_Name => Name_Aft));

      --  For wide character, append encoding method

      elsif Rtyp = Standard_Wide_Character then
         Append_To (Arglist,
           Make_Integer_Literal (Loc,
             Intval => Int (Wide_Character_Encoding_Method)));

      --  For decimal, append Scale and also set to do literal conversion

      elsif Is_Decimal_Fixed_Point_Type (Rtyp) then
         Append_To (Arglist,
           Make_Attribute_Reference (Loc,
             Prefix => New_Reference_To (Ptyp, Loc),
             Attribute_Name => Name_Scale));

         Set_Conversion_OK (First (Arglist));
         Set_Etype (First (Arglist), Tent);
      end if;

      Rewrite (N,
        Make_Function_Call (Loc,
          Name => New_Reference_To (Func_Ent, Loc),
          Parameter_Associations => Arglist));

      Analyze_And_Resolve (N, Standard_String);
   end Expand_Image_Attribute;

   ----------------------------
   -- Expand_Value_Attribute --
   ----------------------------

   --  For scalar types derived from Boolean, Character and integer types
   --  in package Standard, typ'Value (X) expands into:

   --    btyp (Value_xx (X))

   --  where btyp is he base type of the prefix, and

   --    For types whose root type is Character
   --      xx = Character

   --    For types whose root type is Boolean
   --      xx = Boolean

   --    For signed integer types with size <= Integer'Size
   --      xx = Integer

   --    For other signed integer types
   --      xx = Long_Long_Integer

   --    For modular types with modulus <= System.Unsigned_Types.Unsigned
   --      xx = Unsigned

   --    For other modular integer types
   --      xx = Long_Long_Unsigned

   --    For floating-point types and ordinary fixed-point types
   --      xx = Real

   --  For types derived from Wide_Character, typ'Value (X) expands into

   --    Value_Wide_Character (X, Wide_Character_Encoding_Method)

   --  For decimal types with size <= Integer'Size, typ'Value (X)
   --  expands into

   --    btyp?(Value_Decimal (X, typ'Scale));

   --  For all other decimal types, typ'Value (X) expands into

   --    btyp?(Value_Long_Long_Decimal (X, typ'Scale))

   --  For enumeration types other than those derived from types Boolean,
   --  Character, and Wide_Character in Standard, typ'Value (X) expands to:

   --    Enum'Val (Value_Enumeration_NN (typS, typI'Address, Num, X))

   --  where typS and typI and the Lit_Strings and Lit_Indexes entities
   --  from T's root type entitym and Num is Enum'Pos (Enum'Last). The
   --  Value_Enumeration_NN function will search the tables looking for
   --  X and return the position number in the table if found which is
   --  used to provide the result of 'Value (using Enum'Val). If the
   --  value is not found Constraint_Error is raised. The suffix _NN
   --  depends on the element type of typI.

   procedure Expand_Value_Attribute (N : Node_Id) is
      Loc   : constant Source_Ptr := Sloc (N);
      Typ   : constant Entity_Id  := Etype (N);
      Btyp  : constant Entity_Id  := Base_Type (Typ);
      Rtyp  : constant Entity_Id  := Root_Type (Typ);
      Exprs : constant List_Id    := Expressions (N);
      Vid   : RE_Id;
      Args  : List_Id;
      Func  : RE_Id;
      Ttyp  : Entity_Id;

   begin
      Args := Exprs;

      if Rtyp = Standard_Character then
         Vid := RE_Value_Character;

      elsif Rtyp = Standard_Boolean then
         Vid := RE_Value_Boolean;

      elsif Rtyp = Standard_Wide_Character then
         Vid := RE_Value_Wide_Character;
         Append_To (Args,
           Make_Integer_Literal (Loc,
             Intval => Int (Wide_Character_Encoding_Method)));

      elsif     Rtyp = Base_Type (Standard_Short_Short_Integer)
        or else Rtyp = Base_Type (Standard_Short_Integer)
        or else Rtyp = Base_Type (Standard_Integer)
      then
         Vid := RE_Value_Integer;

      elsif Is_Signed_Integer_Type (Rtyp) then
         Vid := RE_Value_Long_Long_Integer;

      elsif Is_Modular_Integer_Type (Rtyp) then
         if Modulus (Rtyp) <= Modulus (RTE (RE_Unsigned)) then
            Vid := RE_Value_Unsigned;
         else
            Vid := RE_Value_Long_Long_Unsigned;
         end if;

      elsif Is_Decimal_Fixed_Point_Type (Rtyp) then
         if UI_To_Int (Esize (Rtyp)) <= Standard_Integer_Size then
            Vid := RE_Value_Decimal;
         else
            Vid := RE_Value_Long_Long_Decimal;
         end if;

         Append_To (Args,
           Make_Attribute_Reference (Loc,
             Prefix => New_Reference_To (Typ, Loc),
             Attribute_Name => Name_Scale));

         Rewrite (N,
           OK_Convert_To (Btyp,
             Make_Function_Call (Loc,
               Name => New_Reference_To (RTE (Vid), Loc),
               Parameter_Associations => Args)));

         Set_Etype (N, Btyp);
         Analyze_And_Resolve (N, Btyp);
         return;

      elsif Is_Real_Type (Rtyp) then
         Vid := RE_Value_Real;

      --  Only other possibility is user defined enumeration type

      else
         pragma Assert (Is_Enumeration_Type (Rtyp));

         --  Case of pragma Discard_Names, transform the Value
         --  attribute to Btyp'Val (Long_Long_Integer'Value (Args))

         if Discard_Names (First_Subtype (Typ))
           or else No (Lit_Strings (Rtyp))
         then
            Rewrite (N,
              Make_Attribute_Reference (Loc,
                Prefix => New_Reference_To (Btyp, Loc),
                Attribute_Name => Name_Val,
                Expressions => New_List (
                  Make_Attribute_Reference (Loc,
                    Prefix =>
                      New_Occurrence_Of (Standard_Long_Long_Integer, Loc),
                    Attribute_Name => Name_Value,
                    Expressions => Args))));

            Analyze_And_Resolve (N, Btyp);

         --  Here for normal case where we have enumeration tables, this
         --  is where we build

         --    T'Val (Value_Enumeration_NN (typS, typI'Address, Num, X))

         else
            Ttyp := Component_Type (Etype (Lit_Indexes (Rtyp)));

            if Ttyp = Standard_Integer_8 then
               Func := RE_Value_Enumeration_8;
            elsif Ttyp = Standard_Integer_16  then
               Func := RE_Value_Enumeration_16;
            else
               Func := RE_Value_Enumeration_32;
            end if;

            Prepend_To (Args,
              Make_Attribute_Reference (Loc,
                Prefix => New_Occurrence_Of (Rtyp, Loc),
                Attribute_Name => Name_Pos,
                Expressions => New_List (
                  Make_Attribute_Reference (Loc,
                    Prefix => New_Occurrence_Of (Rtyp, Loc),
                    Attribute_Name => Name_Last))));

            Prepend_To (Args,
              Make_Attribute_Reference (Loc,
                Prefix => New_Occurrence_Of (Lit_Indexes (Rtyp), Loc),
                Attribute_Name => Name_Address));

            Prepend_To (Args,
              New_Occurrence_Of (Lit_Strings (Rtyp), Loc));

            Rewrite (N,
              Make_Attribute_Reference (Loc,
                Prefix => New_Reference_To (Typ, Loc),
                Attribute_Name => Name_Val,
                Expressions => New_List (
                  Make_Function_Call (Loc,
                    Name =>
                      New_Reference_To (RTE (Func), Loc),
                    Parameter_Associations => Args))));

            Analyze_And_Resolve (N, Btyp);
         end if;

         return;
      end if;

      --  Fall through for all cases except user defined enumeration type
      --  and decimal types, with Vid set to the Id of the entity for the
      --  Value routine and Args set to the list of parameters for the call.

      Rewrite (N,
        Convert_To (Btyp,
          Make_Function_Call (Loc,
            Name => New_Reference_To (RTE (Vid), Loc),
            Parameter_Associations => Args)));

      Analyze_And_Resolve (N, Btyp);
   end Expand_Value_Attribute;

   ----------------------------
   -- Expand_Width_Attribute --
   ----------------------------

   --  The processing here also handles the case of Wide_Width. With the
   --  exceptions noted, the processing is identical

   --  For scalar types derived from Boolean, character and integer types
   --  in package Standard. Note that the Width attribute is computed at
   --  compile time for all cases except those involving non-static sub-
   --  types. For such subtypes, typ'Width and typ'Wide_Width expands into:

   --    Result_Type (xx (yy (Ptyp'First), yy (Ptyp'Last)))

   --  where

   --    For types whose root type is Character
   --      xx = Width_Character (Wide_Width_Character for Wide_Width case)
   --      yy = Character

   --    For types whose root type is Boolean
   --      xx = Width_Boolean
   --      yy = Boolean

   --    For signed integer types
   --      xx = Width_Long_Long_Integer
   --      yy = Long_Long_Integer

   --    For modular integer types
   --      xx = Width_Long_Long_Unsigned
   --      yy = Long_Long_Unsigned

   --  For types derived from Wide_Character, typ'Width expands into

   --    Result_Type (Width_Wide_Character (
   --      Wide_Character (typ'First),
   --      Wide_Character (typ'Last),
   --      Wide_Character_Encoding_Method);

   --  and typ'Wide_Width expands into:

   --    Result_Type (Wide_Width_Wide_Character (
   --      Wide_Character (typ'First),
   --      Wide_Character (typ'Last));

   --  For real types, typ'Width and typ'Wide_Width expand into

   --    if Ptyp'First > Ptyp'Last then 0 else btyp'Width end if

   --  where btyp is the base type. This looks recursive but it isn't
   --  because the base type is always static, and hence the expression
   --  in the else is reduced to an integer literal.

   --  For user defined enumeration types, typ'Width expands into

   --    Result_Type (Width_Enumeration_NN
   --                  (typS,
   --                   typI'Address,
   --                   typ'Pos (typ'First),
   --                   typ'Pos (Typ'Last)));

   --  and typ'Wide_Width expands into:

   --    Result_Type (Wide_Width_Enumeration_NN
   --                  (typS,
   --                   typI,
   --                   typ'Pos (typ'First),
   --                   typ'Pos (Typ'Last))
   --                   Wide_Character_Encoding_Method);

   --  where typS and typI are the enumeration image strings and
   --  indexes table, as described in Build_Enumeration_Image_Tables.
   --  NN is 8/16/32 for depending on the element type for typI.

   procedure Expand_Width_Attribute (N : Node_Id; Wide : Boolean) is
      Loc     : constant Source_Ptr := Sloc (N);
      Typ     : constant Entity_Id  := Etype (N);
      Pref    : constant Node_Id    := Prefix (N);
      Ptyp    : constant Entity_Id  := Etype (Pref);
      Rtyp    : constant Entity_Id  := Root_Type (Ptyp);
      XX      : RE_Id;
      YY      : Entity_Id;
      Arglist : List_Id;
      Ttyp    : Entity_Id;

   begin
      --  Types derived from Standard.Boolean

      if Rtyp = Standard_Boolean then
         XX := RE_Width_Boolean;
         YY := Rtyp;

      --  Types derived from Standard.Character

      elsif Rtyp = Standard_Character then
         if not Wide then
            XX := RE_Width_Character;
         else
            XX := RE_Wide_Width_Character;
         end if;

         YY := Rtyp;

      --  Types derived from Standard.Wide_Character

      elsif Rtyp = Standard_Wide_Character then
         if not Wide then
            XX := RE_Width_Wide_Character;
         else
            XX := RE_Wide_Width_Wide_Character;
         end if;

         YY := Rtyp;

      --  Signed integer types

      elsif Is_Signed_Integer_Type (Rtyp) then
         XX := RE_Width_Long_Long_Integer;
         YY := Standard_Long_Long_Integer;

      --  Modular integer types

      elsif Is_Modular_Integer_Type (Rtyp) then
         XX := RE_Width_Long_Long_Unsigned;
         YY := RTE (RE_Long_Long_Unsigned);

      --  Real types

      elsif Is_Real_Type (Rtyp) then

         Rewrite (N,
           Make_Conditional_Expression (Loc,
             Expressions => New_List (

               Make_Op_Gt (Loc,
                 Left_Opnd =>
                   Make_Attribute_Reference (Loc,
                     Prefix => New_Reference_To (Ptyp, Loc),
                     Attribute_Name => Name_First),

                 Right_Opnd =>
                   Make_Attribute_Reference (Loc,
                     Prefix => New_Reference_To (Ptyp, Loc),
                     Attribute_Name => Name_Last)),

               Make_Integer_Literal (Loc, 0),

               Make_Attribute_Reference (Loc,
                 Prefix => New_Reference_To (Base_Type (Ptyp), Loc),
                 Attribute_Name => Name_Width))));

         Analyze_And_Resolve (N, Typ);
         return;

      --  User defined enumeration types

      else
         pragma Assert (Is_Enumeration_Type (Rtyp));

         Ttyp := Component_Type (Etype (Lit_Indexes (Rtyp)));

         if not Wide then
            if Ttyp = Standard_Integer_8 then
               XX := RE_Width_Enumeration_8;
            elsif Ttyp = Standard_Integer_16  then
               XX := RE_Width_Enumeration_16;
            else
               XX := RE_Width_Enumeration_32;
            end if;

         else
            if Ttyp = Standard_Integer_8 then
               XX := RE_Wide_Width_Enumeration_8;
            elsif Ttyp = Standard_Integer_16  then
               XX := RE_Wide_Width_Enumeration_16;
            else
               XX := RE_Wide_Width_Enumeration_32;
            end if;
         end if;

         Arglist :=
           New_List (
             New_Occurrence_Of (Lit_Strings (Rtyp), Loc),

             Make_Attribute_Reference (Loc,
               Prefix => New_Occurrence_Of (Lit_Indexes (Rtyp), Loc),
               Attribute_Name => Name_Address),

             Make_Attribute_Reference (Loc,
               Prefix => New_Reference_To (Ptyp, Loc),
               Attribute_Name => Name_Pos,

               Expressions => New_List (
                 Make_Attribute_Reference (Loc,
                   Prefix => New_Reference_To (Ptyp, Loc),
                   Attribute_Name => Name_First))),

             Make_Attribute_Reference (Loc,
               Prefix => New_Reference_To (Ptyp, Loc),
               Attribute_Name => Name_Pos,

               Expressions => New_List (
                 Make_Attribute_Reference (Loc,
                   Prefix => New_Reference_To (Ptyp, Loc),
                   Attribute_Name => Name_Last))));

         --  For enumeration'Wide_Width, add encoding method parameter

         if Wide then
            Append_To (Arglist,
              Make_Integer_Literal (Loc,
                Intval => Int (Wide_Character_Encoding_Method)));
         end if;

         Rewrite (N,
           Convert_To (Typ,
             Make_Function_Call (Loc,
               Name => New_Reference_To (RTE (XX), Loc),
               Parameter_Associations => Arglist)));

         Analyze_And_Resolve (N, Typ);
         return;
      end if;

      --  If we fall through XX and YY are set

      Arglist := New_List (
        Convert_To (YY,
          Make_Attribute_Reference (Loc,
            Prefix => New_Reference_To (Ptyp, Loc),
            Attribute_Name => Name_First)),

        Convert_To (YY,
          Make_Attribute_Reference (Loc,
            Prefix => New_Reference_To (Ptyp, Loc),
            Attribute_Name => Name_Last)));

      --  For Wide_Character'Width, add encoding method parameter

      if Rtyp = Standard_Wide_Character and then Wide then
         Append_To (Arglist,
           Make_Integer_Literal (Loc,
             Intval => Int (Wide_Character_Encoding_Method)));
      end if;

      Rewrite (N,
        Convert_To (Typ,
          Make_Function_Call (Loc,
            Name => New_Reference_To (RTE (XX), Loc),
            Parameter_Associations => Arglist)));

      Analyze_And_Resolve (N, Typ);
   end Expand_Width_Attribute;

end Exp_Imgv;