[thirdparty/gcc.git] / gcc / ada / repinfo.adb

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                              R E P I N F O                               --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1999-2020, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with Alloc;
with Atree;   use Atree;
with Casing;  use Casing;
with Debug;   use Debug;
with Einfo;   use Einfo;
with Lib;     use Lib;
with Namet;   use Namet;
with Nlists;  use Nlists;
with Opt;     use Opt;
with Output;  use Output;
with Sem_Aux; use Sem_Aux;
with Sinfo;   use Sinfo;
with Sinput;  use Sinput;
with Snames;  use Snames;
with Stringt; use Stringt;
with Table;
with Uname;   use Uname;
with Urealp;  use Urealp;

with Ada.Unchecked_Conversion;

with GNAT.HTable;

package body Repinfo is

   SSU : constant := 8;
   --  Value for Storage_Unit, we do not want to get this from TTypes, since
   --  this introduces problematic dependencies in ASIS, and in any case this
   --  value is assumed to be 8 for the implementation of the DDA.

   ---------------------------------------
   -- Representation of GCC Expressions --
   ---------------------------------------

   --    A table internal to this unit is used to hold the values of back
   --    annotated expressions.

   --    Node values are stored as Uint values using the negative of the node
   --    index in this table. Constants appear as non-negative Uint values.

   type Exp_Node is record
      Expr : TCode;
      Op1  : Node_Ref_Or_Val;
      Op2  : Node_Ref_Or_Val;
      Op3  : Node_Ref_Or_Val;
   end record;

   --  The following representation clause ensures that the above record
   --  has no holes. We do this so that when instances of this record are
   --  written, we do not write uninitialized values to the file.

   for Exp_Node use record
      Expr at  0 range 0 .. 31;
      Op1  at  4 range 0 .. 31;
      Op2  at  8 range 0 .. 31;
      Op3  at 12 range 0 .. 31;
   end record;

   for Exp_Node'Size use 16 * 8;
   --  This ensures that we did not leave out any fields

   package Rep_Table is new Table.Table (
      Table_Component_Type => Exp_Node,
      Table_Index_Type     => Nat,
      Table_Low_Bound      => 1,
      Table_Initial        => Alloc.Rep_Table_Initial,
      Table_Increment      => Alloc.Rep_Table_Increment,
      Table_Name           => "BE_Rep_Table");

   --------------------------------------------------------------
   -- Representation of Front-End Dynamic Size/Offset Entities --
   --------------------------------------------------------------

   package Dynamic_SO_Entity_Table is new Table.Table (
      Table_Component_Type => Entity_Id,
      Table_Index_Type     => Nat,
      Table_Low_Bound      => 1,
      Table_Initial        => Alloc.Rep_Table_Initial,
      Table_Increment      => Alloc.Rep_Table_Increment,
      Table_Name           => "FE_Rep_Table");

   Unit_Casing : Casing_Type;
   --  Identifier casing for current unit. This is set by List_Rep_Info for
   --  each unit, before calling subprograms which may read it.

   Need_Separator : Boolean;
   --  Set True if a separator is needed before outputting any information for
   --  the current entity.

   ------------------------------
   -- Set of Relevant Entities --
   ------------------------------

   Relevant_Entities_Size : constant := 4093;
   --  Number of headers in hash table

   subtype Entity_Header_Num is Integer range 0 .. Relevant_Entities_Size - 1;
   --  Range of headers in hash table

   function Entity_Hash (Id : Entity_Id) return Entity_Header_Num;
   --  Simple hash function for Entity_Ids

   package Relevant_Entities is new GNAT.Htable.Simple_HTable
     (Header_Num => Entity_Header_Num,
      Element    => Boolean,
      No_Element => False,
      Key        => Entity_Id,
      Hash       => Entity_Hash,
      Equal      => "=");
   --  Hash table to record which compiler-generated entities are relevant

   -----------------------
   -- Local Subprograms --
   -----------------------

   function Back_End_Layout return Boolean;
   --  Test for layout mode, True = back end, False = front end. This function
   --  is used rather than checking the configuration parameter because we do
   --  not want Repinfo to depend on Targparm (for ASIS)

   procedure List_Entities
     (Ent              : Entity_Id;
      Bytes_Big_Endian : Boolean;
      In_Subprogram    : Boolean := False);
   --  This procedure lists the entities associated with the entity E, starting
   --  with the First_Entity and using the Next_Entity link. If a nested
   --  package is found, entities within the package are recursively processed.
   --  When recursing within a subprogram body, Is_Subprogram suppresses
   --  duplicate information about signature.

   procedure List_Name (Ent : Entity_Id);
   --  List name of entity Ent in appropriate case. The name is listed with
   --  full qualification up to but not including the compilation unit name.

   procedure List_Array_Info (Ent : Entity_Id; Bytes_Big_Endian : Boolean);
   --  List representation info for array type Ent

   procedure List_Common_Type_Info (Ent : Entity_Id);
   --  List common type info (name, size, alignment) for type Ent

   procedure List_Linker_Section (Ent : Entity_Id);
   --  List linker section for Ent (caller has checked that Ent is an entity
   --  for which the Linker_Section_Pragma field is defined).

   procedure List_Location (Ent : Entity_Id);
   --  List location information for Ent

   procedure List_Object_Info (Ent : Entity_Id);
   --  List representation info for object Ent

   procedure List_Record_Info (Ent : Entity_Id; Bytes_Big_Endian : Boolean);
   --  List representation info for record type Ent

   procedure List_Scalar_Storage_Order
     (Ent              : Entity_Id;
      Bytes_Big_Endian : Boolean);
   --  List scalar storage order information for record or array type Ent.
   --  Also includes bit order information for record types, if necessary.

   procedure List_Subprogram_Info (Ent : Entity_Id);
   --  List subprogram info for subprogram Ent

   procedure List_Type_Info (Ent : Entity_Id);
   --  List type info for type Ent

   function Rep_Not_Constant (Val : Node_Ref_Or_Val) return Boolean;
   --  Returns True if Val represents a variable value, and False if it
   --  represents a value that is fixed at compile time.

   procedure Spaces (N : Natural);
   --  Output given number of spaces

   procedure Write_Info_Line (S : String);
   --  Routine to write a line to Repinfo output file. This routine is passed
   --  as a special output procedure to Output.Set_Special_Output. Note that
   --  Write_Info_Line is called with an EOL character at the end of each line,
   --  as per the Output spec, but the internal call to the appropriate routine
   --  in Osint requires that the end of line sequence be stripped off.

   procedure Write_Mechanism (M : Mechanism_Type);
   --  Writes symbolic string for mechanism represented by M

   procedure Write_Separator;
   --  Called before outputting anything for an entity. Ensures that
   --  a separator precedes the output for a particular entity.

   procedure Write_Unknown_Val;
   --  Writes symbolic string for an unknown or non-representable value

   procedure Write_Val (Val : Node_Ref_Or_Val; Paren : Boolean := False);
   --  Given a representation value, write it out. No_Uint values or values
   --  dependent on discriminants are written as two question marks. If the
   --  flag Paren is set, then the output is surrounded in parentheses if it is
   --  other than a simple value.

   ---------------------
   -- Back_End_Layout --
   ---------------------

   function Back_End_Layout return Boolean is
   begin
      --  We have back-end layout if the back end has made any entries in the
      --  table of GCC expressions, otherwise we have front-end layout.

      return Rep_Table.Last > 0;
   end Back_End_Layout;

   ------------------------
   -- Create_Discrim_Ref --
   ------------------------

   function Create_Discrim_Ref (Discr : Entity_Id) return Node_Ref is
   begin
      return Create_Node
        (Expr => Discrim_Val,
         Op1  => Discriminant_Number (Discr));
   end Create_Discrim_Ref;

   ---------------------------
   -- Create_Dynamic_SO_Ref --
   ---------------------------

   function Create_Dynamic_SO_Ref (E : Entity_Id) return Dynamic_SO_Ref is
   begin
      Dynamic_SO_Entity_Table.Append (E);
      return UI_From_Int (-Dynamic_SO_Entity_Table.Last);
   end Create_Dynamic_SO_Ref;

   -----------------
   -- Create_Node --
   -----------------

   function Create_Node
     (Expr : TCode;
      Op1  : Node_Ref_Or_Val;
      Op2  : Node_Ref_Or_Val := No_Uint;
      Op3  : Node_Ref_Or_Val := No_Uint) return Node_Ref
   is
   begin
      Rep_Table.Append (
        (Expr => Expr,
         Op1  => Op1,
         Op2  => Op2,
         Op3  => Op3));
      return UI_From_Int (-Rep_Table.Last);
   end Create_Node;

   -----------------
   -- Entity_Hash --
   -----------------

   function Entity_Hash (Id : Entity_Id) return Entity_Header_Num is
   begin
      return Entity_Header_Num (Id mod Relevant_Entities_Size);
   end Entity_Hash;

   ---------------------------
   -- Get_Dynamic_SO_Entity --
   ---------------------------

   function Get_Dynamic_SO_Entity (U : Dynamic_SO_Ref) return Entity_Id is
   begin
      return Dynamic_SO_Entity_Table.Table (-UI_To_Int (U));
   end Get_Dynamic_SO_Entity;

   -----------------------
   -- Is_Dynamic_SO_Ref --
   -----------------------

   function Is_Dynamic_SO_Ref (U : SO_Ref) return Boolean is
   begin
      return U < Uint_0;
   end Is_Dynamic_SO_Ref;

   ----------------------
   -- Is_Static_SO_Ref --
   ----------------------

   function Is_Static_SO_Ref (U : SO_Ref) return Boolean is
   begin
      return U >= Uint_0;
   end Is_Static_SO_Ref;

   ---------
   -- lgx --
   ---------

   procedure lgx (U : Node_Ref_Or_Val) is
   begin
      List_GCC_Expression (U);
      Write_Eol;
   end lgx;

   ----------------------
   -- List_Array_Info --
   ----------------------

   procedure List_Array_Info (Ent : Entity_Id; Bytes_Big_Endian : Boolean) is
   begin
      Write_Separator;

      if List_Representation_Info_To_JSON then
         Write_Line ("{");
      end if;

      List_Common_Type_Info (Ent);

      if List_Representation_Info_To_JSON then
         Write_Line (",");
         Write_Str ("  ""Component_Size"": ");
         Write_Val (Component_Size (Ent));
      else
         Write_Str ("for ");
         List_Name (Ent);
         Write_Str ("'Component_Size use ");
         Write_Val (Component_Size (Ent));
         Write_Line (";");
      end if;

      List_Scalar_Storage_Order (Ent, Bytes_Big_Endian);

      List_Linker_Section (Ent);

      if List_Representation_Info_To_JSON then
         Write_Eol;
         Write_Line ("}");
      end if;

      --  The component type is relevant for an array

      if List_Representation_Info = 4
        and then Is_Itype (Component_Type (Base_Type (Ent)))
      then
         Relevant_Entities.Set (Component_Type (Base_Type (Ent)), True);
      end if;
   end List_Array_Info;

   ---------------------------
   -- List_Common_Type_Info --
   ---------------------------

   procedure List_Common_Type_Info (Ent : Entity_Id) is
   begin
      if List_Representation_Info_To_JSON then
         Write_Str ("  ""name"": """);
         List_Name (Ent);
         Write_Line (""",");
         List_Location (Ent);
      end if;

      --  Do not list size info for unconstrained arrays, not meaningful

      if Is_Array_Type (Ent) and then not Is_Constrained (Ent) then
         null;

      else
         --  If Esize and RM_Size are the same, list as Size. This is a common
         --  case, which we may as well list in simple form.

         if Esize (Ent) = RM_Size (Ent) then
            if List_Representation_Info_To_JSON then
               Write_Str ("  ""Size"": ");
               Write_Val (Esize (Ent));
               Write_Line (",");
            else
               Write_Str ("for ");
               List_Name (Ent);
               Write_Str ("'Size use ");
               Write_Val (Esize (Ent));
               Write_Line (";");
            end if;

         --  Otherwise list size values separately

         else
            if List_Representation_Info_To_JSON then
               Write_Str ("  ""Object_Size"": ");
               Write_Val (Esize (Ent));
               Write_Line (",");

               Write_Str ("  ""Value_Size"": ");
               Write_Val (RM_Size (Ent));
               Write_Line (",");

            else
               Write_Str ("for ");
               List_Name (Ent);
               Write_Str ("'Object_Size use ");
               Write_Val (Esize (Ent));
               Write_Line (";");

               Write_Str ("for ");
               List_Name (Ent);
               Write_Str ("'Value_Size use ");
               Write_Val (RM_Size (Ent));
               Write_Line (";");
            end if;
         end if;
      end if;

      if List_Representation_Info_To_JSON then
         Write_Str ("  ""Alignment"": ");
         Write_Val (Alignment (Ent));
      else
         Write_Str ("for ");
         List_Name (Ent);
         Write_Str ("'Alignment use ");
         Write_Val (Alignment (Ent));
         Write_Line (";");
      end if;
   end List_Common_Type_Info;

   -------------------
   -- List_Entities --
   -------------------

   procedure List_Entities
     (Ent              : Entity_Id;
      Bytes_Big_Endian : Boolean;
      In_Subprogram    : Boolean := False)
   is
      Body_E : Entity_Id;
      E      : Entity_Id;

      function Find_Declaration (E : Entity_Id) return Node_Id;
      --  Utility to retrieve declaration node for entity in the
      --  case of package bodies and subprograms.

      ----------------------
      -- Find_Declaration --
      ----------------------

      function Find_Declaration (E : Entity_Id) return Node_Id is
         Decl : Node_Id;

      begin
         Decl := Parent (E);
         while Present (Decl)
           and then Nkind (Decl) /= N_Package_Body
           and then Nkind (Decl) /= N_Subprogram_Declaration
           and then Nkind (Decl) /= N_Subprogram_Body
         loop
            Decl := Parent (Decl);
         end loop;

         return Decl;
      end Find_Declaration;

   --  Start of processing for List_Entities

   begin
      --  List entity if we have one, and it is not a renaming declaration.
      --  For renamings, we don't get proper information, and really it makes
      --  sense to restrict the output to the renamed entity.

      if Present (Ent)
        and then Nkind (Declaration_Node (Ent)) not in N_Renaming_Declaration
        and then not Is_Ignored_Ghost_Entity (Ent)
      then
         --  If entity is a subprogram and we are listing mechanisms,
         --  then we need to list mechanisms for this entity. We skip this
         --  if it is a nested subprogram, as the information has already
         --  been produced when listing the enclosing scope.

         if List_Representation_Info_Mechanisms
           and then (Is_Subprogram (Ent)
                      or else Ekind (Ent) = E_Entry
                      or else Ekind (Ent) = E_Entry_Family)
           and then not In_Subprogram
         then
            List_Subprogram_Info (Ent);
         end if;

         E := First_Entity (Ent);
         while Present (E) loop
            --  We list entities that come from source (excluding private or
            --  incomplete types or deferred constants, for which we will list
            --  the information for the full view). If requested, we also list
            --  relevant entities that have been generated when processing the
            --  original entities coming from source. But if debug flag A is
            --  set, then all entities are listed.

            if ((Comes_From_Source (E)
                   or else (Ekind (E) = E_Block
                              and then
                            Nkind (Parent (E)) = N_Implicit_Label_Declaration
                              and then
                            Comes_From_Source (Label_Construct (Parent (E)))))
              and then not Is_Incomplete_Or_Private_Type (E)
              and then not (Ekind (E) = E_Constant
                              and then Present (Full_View (E))))
              or else (List_Representation_Info = 4
                         and then Relevant_Entities.Get (E))
              or else Debug_Flag_AA
            then
               if Is_Subprogram (E) then
                  if List_Representation_Info_Mechanisms then
                     List_Subprogram_Info (E);
                  end if;

                  --  Recurse into entities local to subprogram

                  List_Entities (E, Bytes_Big_Endian, True);

               elsif Ekind_In (E, E_Entry,
                                  E_Entry_Family,
                                  E_Subprogram_Type)
               then
                  if List_Representation_Info_Mechanisms then
                     List_Subprogram_Info (E);
                  end if;

               elsif Is_Record_Type (E) then
                  if List_Representation_Info >= 1 then
                     List_Record_Info (E, Bytes_Big_Endian);
                  end if;

                  --  Recurse into entities local to a record type

                  if List_Representation_Info = 4 then
                     List_Entities (E, Bytes_Big_Endian, False);
                  end if;

               elsif Is_Array_Type (E) then
                  if List_Representation_Info >= 1 then
                     List_Array_Info (E, Bytes_Big_Endian);
                  end if;

               elsif Is_Type (E) then
                  if List_Representation_Info >= 2 then
                     List_Type_Info (E);
                  end if;

               --  Note that formals are not annotated so we skip them here

               elsif Ekind_In (E, E_Constant,
                                  E_Loop_Parameter,
                                  E_Variable)
               then
                  if List_Representation_Info >= 2 then
                     List_Object_Info (E);
                  end if;
               end if;

               --  Recurse into nested package, but not if they are package
               --  renamings (in particular renamings of the enclosing package,
               --  as for some Java bindings and for generic instances).

               if Ekind (E) = E_Package then
                  if No (Renamed_Object (E)) then
                     List_Entities (E, Bytes_Big_Endian);
                  end if;

               --  Recurse into bodies

               elsif Ekind_In (E, E_Package_Body,
                                  E_Protected_Body,
                                  E_Protected_Type,
                                  E_Subprogram_Body,
                                  E_Task_Body,
                                  E_Task_Type)
               then
                  List_Entities (E, Bytes_Big_Endian);

               --  Recurse into blocks

               elsif Ekind (E) = E_Block then
                  List_Entities (E, Bytes_Big_Endian);
               end if;
            end if;

            Next_Entity (E);
         end loop;

         --  For a package body, the entities of the visible subprograms are
         --  declared in the corresponding spec. Iterate over its entities in
         --  order to handle properly the subprogram bodies. Skip bodies in
         --  subunits, which are listed independently.

         if Ekind (Ent) = E_Package_Body
           and then Present (Corresponding_Spec (Find_Declaration (Ent)))
         then
            E := First_Entity (Corresponding_Spec (Find_Declaration (Ent)));
            while Present (E) loop
               if Is_Subprogram (E)
                 and then
                   Nkind (Find_Declaration (E)) = N_Subprogram_Declaration
               then
                  Body_E := Corresponding_Body (Find_Declaration (E));

                  if Present (Body_E)
                    and then
                      Nkind (Parent (Find_Declaration (Body_E))) /= N_Subunit
                  then
                     List_Entities (Body_E, Bytes_Big_Endian);
                  end if;
               end if;

               Next_Entity (E);
            end loop;
         end if;
      end if;
   end List_Entities;

   -------------------------
   -- List_GCC_Expression --
   -------------------------

   procedure List_GCC_Expression (U : Node_Ref_Or_Val) is

      procedure Print_Expr (Val : Node_Ref_Or_Val);
      --  Internal recursive procedure to print expression

      ----------------
      -- Print_Expr --
      ----------------

      procedure Print_Expr (Val : Node_Ref_Or_Val) is
      begin
         if Val >= 0 then
            UI_Write (Val, Decimal);

         else
            declare
               Node : Exp_Node renames Rep_Table.Table (-UI_To_Int (Val));

               procedure Unop (S : String);
               --  Output text for unary operator with S being operator name

               procedure Binop (S : String);
               --  Output text for binary operator with S being operator name

               ----------
               -- Unop --
               ----------

               procedure Unop (S : String) is
               begin
                  if List_Representation_Info_To_JSON then
                     Write_Str ("{ ""code"": """);
                     if S (S'Last) = ' ' then
                        Write_Str (S (S'First .. S'Last - 1));
                     else
                        Write_Str (S);
                     end if;
                     Write_Str (""", ""operands"": [ ");
                     Print_Expr (Node.Op1);
                     Write_Str (" ] }");
                  else
                     Write_Str (S);
                     Print_Expr (Node.Op1);
                  end if;
               end Unop;

               -----------
               -- Binop --
               -----------

               procedure Binop (S : String) is
               begin
                  if List_Representation_Info_To_JSON then
                     Write_Str ("{ ""code"": """);
                     Write_Str (S (S'First + 1 .. S'Last - 1));
                     Write_Str (""", ""operands"": [ ");
                     Print_Expr (Node.Op1);
                     Write_Str (", ");
                     Print_Expr (Node.Op2);
                     Write_Str (" ] }");
                  else
                     Write_Char ('(');
                     Print_Expr (Node.Op1);
                     Write_Str (S);
                     Print_Expr (Node.Op2);
                     Write_Char (')');
                  end if;
               end Binop;

            --  Start of processing for Print_Expr

            begin
               case Node.Expr is
                  when Cond_Expr =>
                     if List_Representation_Info_To_JSON then
                        Write_Str ("{ ""code"": ""?<>""");
                        Write_Str (", ""operands"": [ ");
                        Print_Expr (Node.Op1);
                        Write_Str (", ");
                        Print_Expr (Node.Op2);
                        Write_Str (", ");
                        Print_Expr (Node.Op3);
                        Write_Str (" ] }");
                     else
                        Write_Str ("(if ");
                        Print_Expr (Node.Op1);
                        Write_Str (" then ");
                        Print_Expr (Node.Op2);
                        Write_Str (" else ");
                        Print_Expr (Node.Op3);
                        Write_Str (" end)");
                     end if;

                  when Plus_Expr =>
                     Binop (" + ");

                  when Minus_Expr =>
                     Binop (" - ");

                  when Mult_Expr =>
                     Binop (" * ");

                  when Trunc_Div_Expr =>
                     Binop (" /t ");

                  when Ceil_Div_Expr =>
                     Binop (" /c ");

                  when Floor_Div_Expr =>
                     Binop (" /f ");

                  when Trunc_Mod_Expr =>
                     Binop (" modt ");

                  when Ceil_Mod_Expr =>
                     Binop (" modc ");

                  when Floor_Mod_Expr =>
                     Binop (" modf ");

                  when Exact_Div_Expr =>
                     Binop (" /e ");

                  when Negate_Expr =>
                     Unop ("-");

                  when Min_Expr =>
                     Binop (" min ");

                  when Max_Expr =>
                     Binop (" max ");

                  when Abs_Expr =>
                     Unop ("abs ");

                  when Truth_And_Expr =>
                     Binop (" and ");

                  when Truth_Or_Expr =>
                     Binop (" or ");

                  when Truth_Xor_Expr =>
                     Binop (" xor ");

                  when Truth_Not_Expr =>
                     Unop ("not ");

                  when Lt_Expr =>
                     Binop (" < ");

                  when Le_Expr =>
                     Binop (" <= ");

                  when Gt_Expr =>
                     Binop (" > ");

                  when Ge_Expr =>
                     Binop (" >= ");

                  when Eq_Expr =>
                     Binop (" == ");

                  when Ne_Expr =>
                     Binop (" != ");

                  when Bit_And_Expr =>
                     Binop (" & ");

                  when Discrim_Val =>
                     Unop ("#");

                  when Dynamic_Val =>
                     Unop ("var");
               end case;
            end;
         end if;
      end Print_Expr;

   --  Start of processing for List_GCC_Expression

   begin
      if U = No_Uint then
         Write_Unknown_Val;
      else
         Print_Expr (U);
      end if;
   end List_GCC_Expression;

   -------------------------
   -- List_Linker_Section --
   -------------------------

   procedure List_Linker_Section (Ent : Entity_Id) is
      function Expr_Value_S (N : Node_Id) return Node_Id;
      --  Returns the folded value of the expression. This function is called
      --  in instances where it has already been determined that the expression
      --  is static or its value is known at compile time. This version is used
      --  for string types and returns the corresponding N_String_Literal node.
      --  NOTE: This is an exact copy of Sem_Eval.Expr_Value_S. Licensing stops
      --  Repinfo from within Sem_Eval. Once ASIS is removed, and the licenses
      --  are modified, Repinfo should be able to rely on Sem_Eval.

      ------------------
      -- Expr_Value_S --
      ------------------

      function Expr_Value_S (N : Node_Id) return Node_Id is
      begin
         if Nkind (N) = N_String_Literal then
            return N;
         else
            pragma Assert (Ekind (Entity (N)) = E_Constant);
            return Expr_Value_S (Constant_Value (Entity (N)));
         end if;
      end Expr_Value_S;

      --  Local variables

      Args : List_Id;
      Sect : Node_Id;

   --  Start of processing for List_Linker_Section

   begin
      if Present (Linker_Section_Pragma (Ent)) then
         Args := Pragma_Argument_Associations (Linker_Section_Pragma (Ent));
         Sect := Expr_Value_S (Get_Pragma_Arg (Last (Args)));

         if List_Representation_Info_To_JSON then
            Write_Line (",");
            Write_Str ("  ""Linker_Section"": """);
         else
            Write_Str ("pragma Linker_Section (");
            List_Name (Ent);
            Write_Str (", """);
         end if;

         pragma Assert (Nkind (Sect) = N_String_Literal);
         String_To_Name_Buffer (Strval (Sect));
         Write_Str (Name_Buffer (1 .. Name_Len));
         Write_Str ("""");
         if not List_Representation_Info_To_JSON then
            Write_Line (");");
         end if;
      end if;
   end List_Linker_Section;

   -------------------
   -- List_Location --
   -------------------

   procedure List_Location (Ent : Entity_Id) is
   begin
      pragma Assert (List_Representation_Info_To_JSON);
      Write_Str ("  ""location"": """);
      Write_Location (Sloc (Ent));
      Write_Line (""",");
   end List_Location;

   ---------------
   -- List_Name --
   ---------------

   procedure List_Name (Ent : Entity_Id) is
      C : Character;

   begin
      --  List the qualified name recursively, except
      --  at compilation unit level in default mode.

      if Is_Compilation_Unit (Ent) then
         null;
      elsif not Is_Compilation_Unit (Scope (Ent))
        or else List_Representation_Info_To_JSON
      then
         List_Name (Scope (Ent));
         Write_Char ('.');
      end if;

      Get_Unqualified_Decoded_Name_String (Chars (Ent));
      Set_Casing (Unit_Casing);

      --  The name of operators needs to be properly escaped for JSON

      for J in 1 .. Name_Len loop
         C := Name_Buffer (J);
         if C = '"' and then List_Representation_Info_To_JSON then
            Write_Char ('\');
         end if;
         Write_Char (C);
      end loop;
   end List_Name;

   ---------------------
   -- List_Object_Info --
   ---------------------

   procedure List_Object_Info (Ent : Entity_Id) is
   begin
      Write_Separator;

      if List_Representation_Info_To_JSON then
         Write_Line ("{");

         Write_Str ("  ""name"": """);
         List_Name (Ent);
         Write_Line (""",");
         List_Location (Ent);

         Write_Str ("  ""Size"": ");
         Write_Val (Esize (Ent));
         Write_Line (",");

         Write_Str ("  ""Alignment"": ");
         Write_Val (Alignment (Ent));

         List_Linker_Section (Ent);

         Write_Eol;
         Write_Line ("}");
      else
         Write_Str ("for ");
         List_Name (Ent);
         Write_Str ("'Size use ");
         Write_Val (Esize (Ent));
         Write_Line (";");

         Write_Str ("for ");
         List_Name (Ent);
         Write_Str ("'Alignment use ");
         Write_Val (Alignment (Ent));
         Write_Line (";");

         List_Linker_Section (Ent);
      end if;

      --  The type is relevant for an object

      if List_Representation_Info = 4 and then Is_Itype (Etype (Ent)) then
         Relevant_Entities.Set (Etype (Ent), True);
      end if;
   end List_Object_Info;

   ----------------------
   -- List_Record_Info --
   ----------------------

   procedure List_Record_Info (Ent : Entity_Id; Bytes_Big_Endian : Boolean) is
      procedure Compute_Max_Length
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix_Length      : Natural := 0);
      --  Internal recursive procedure to compute the max length

      procedure List_Component_Layout
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix             : String := "";
         Indent             : Natural := 0);
      --  Procedure to display the layout of a single component

      procedure List_Record_Layout
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix             : String := "");
      --  Internal recursive procedure to display the layout

      procedure List_Structural_Record_Layout
        (Ent       : Entity_Id;
         Outer_Ent : Entity_Id;
         Variant   : Node_Id := Empty;
         Indent    : Natural := 0);
      --  Internal recursive procedure to display the structural layout

      Incomplete_Layout : exception;
      --  Exception raised if the layout is incomplete in -gnatc mode

      Not_In_Extended_Main : exception;
      --  Exception raised when an ancestor is not declared in the main unit

      Max_Name_Length : Natural := 0;
      Max_Spos_Length : Natural := 0;

      ------------------------
      -- Compute_Max_Length --
      ------------------------

      procedure Compute_Max_Length
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix_Length      : Natural := 0)
      is
         Comp : Entity_Id;

      begin
         Comp := First_Component_Or_Discriminant (Ent);
         while Present (Comp) loop

            --  Skip discriminant in unchecked union (since it is not there!)

            if Ekind (Comp) = E_Discriminant
              and then Is_Unchecked_Union (Ent)
            then
               goto Continue;
            end if;

            --  Skip _Parent component in extension (to avoid overlap)

            if Chars (Comp) = Name_uParent then
               goto Continue;
            end if;

            --  All other cases

            declare
               Ctyp : constant Entity_Id := Underlying_Type (Etype (Comp));
               Bofs : constant Uint      := Component_Bit_Offset (Comp);
               Npos : Uint;
               Fbit : Uint;
               Spos : Uint;
               Sbit : Uint;

               Name_Length : Natural;

            begin
               Get_Decoded_Name_String (Chars (Comp));
               Name_Length := Prefix_Length + Name_Len;

               if Rep_Not_Constant (Bofs) then

                  --  If the record is not packed, then we know that all fields
                  --  whose position is not specified have starting normalized
                  --  bit position of zero.

                  if Unknown_Normalized_First_Bit (Comp)
                    and then not Is_Packed (Ent)
                  then
                     Set_Normalized_First_Bit (Comp, Uint_0);
                  end if;

                  UI_Image_Length := 2; -- For "??" marker
               else
                  Npos := Bofs / SSU;
                  Fbit := Bofs mod SSU;

                  --  Complete annotation in case not done

                  if Unknown_Normalized_First_Bit (Comp) then
                     Set_Normalized_Position  (Comp, Npos);
                     Set_Normalized_First_Bit (Comp, Fbit);
                  end if;

                  Spos := Starting_Position  + Npos;
                  Sbit := Starting_First_Bit + Fbit;

                  if Sbit >= SSU then
                     Spos := Spos + 1;
                     Sbit := Sbit - SSU;
                  end if;

                  --  If extended information is requested, recurse fully into
                  --  record components, i.e. skip the outer level.

                  if List_Representation_Info_Extended
                    and then Is_Record_Type (Ctyp)
                  then
                     Compute_Max_Length (Ctyp, Spos, Sbit, Name_Length + 1);
                     goto Continue;
                  end if;

                  UI_Image (Spos);
               end if;

               Max_Name_Length := Natural'Max (Max_Name_Length, Name_Length);
               Max_Spos_Length :=
                 Natural'Max (Max_Spos_Length, UI_Image_Length);
            end;

         <<Continue>>
            Next_Component_Or_Discriminant (Comp);
         end loop;
      end Compute_Max_Length;

      ---------------------------
      -- List_Component_Layout --
      ---------------------------

      procedure List_Component_Layout
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix             : String := "";
         Indent             : Natural := 0)
      is
         Esiz  : constant Uint := Esize (Ent);
         Npos  : constant Uint := Normalized_Position (Ent);
         Fbit  : constant Uint := Normalized_First_Bit (Ent);
         Spos  : Uint;
         Sbit  : Uint;
         Lbit  : Uint;

      begin
         if List_Representation_Info_To_JSON then
            Spaces (Indent);
            Write_Line ("    {");
            Spaces (Indent);
            Write_Str ("      ""name"": """);
            Write_Str (Prefix);
            Write_Str (Name_Buffer (1 .. Name_Len));
            Write_Line (""",");
            if Ekind (Ent) = E_Discriminant then
               Spaces (Indent);
               Write_Str ("      ""discriminant"": ");
               UI_Write (Discriminant_Number (Ent), Decimal);
               Write_Line (",");
            end if;
            Spaces (Indent);
            Write_Str ("      ""Position"": ");
         else
            Write_Str ("   ");
            Write_Str (Prefix);
            Write_Str (Name_Buffer (1 .. Name_Len));
            Spaces (Max_Name_Length - Prefix'Length - Name_Len);
            Write_Str (" at ");
         end if;

         if Known_Static_Normalized_Position (Ent) then
            Spos := Starting_Position  + Npos;
            Sbit := Starting_First_Bit + Fbit;

            if Sbit >= SSU then
               Spos := Spos + 1;
            end if;

            UI_Image (Spos);
            Spaces (Max_Spos_Length - UI_Image_Length);
            Write_Str (UI_Image_Buffer (1 .. UI_Image_Length));

         elsif Known_Normalized_Position (Ent)
           and then List_Representation_Info >= 3
         then
            Spaces (Max_Spos_Length - 2);

            if Starting_Position /= Uint_0 then
               UI_Write (Starting_Position, Decimal);
               Write_Str (" + ");
            end if;

            Write_Val (Npos);

         else
            Write_Unknown_Val;
         end if;

         if List_Representation_Info_To_JSON then
            Write_Line (",");
            Spaces (Indent);
            Write_Str ("      ""First_Bit"": ");
         else
            Write_Str (" range  ");
         end if;

         Sbit := Starting_First_Bit + Fbit;

         if Sbit >= SSU then
            Sbit := Sbit - SSU;
         end if;

         UI_Write (Sbit, Decimal);

         if List_Representation_Info_To_JSON then
            Write_Line (", ");
            Spaces (Indent);
            Write_Str ("      ""Size"": ");
         else
            Write_Str (" .. ");
         end if;

         --  Allowing Uint_0 here is an annoying special case. Really this
         --  should be a fine Esize value but currently it means unknown,
         --  except that we know after gigi has back annotated that a size
         --  of zero is real, since otherwise gigi back annotates using
         --  No_Uint as the value to indicate unknown.

         if (Esize (Ent) = Uint_0 or else Known_Static_Esize (Ent))
           and then Known_Static_Normalized_First_Bit (Ent)
         then
            Lbit := Sbit + Esiz - 1;

            if List_Representation_Info_To_JSON then
               UI_Write (Esiz, Decimal);
            else
               if Lbit >= 0 and then Lbit < 10 then
                  Write_Char (' ');
               end if;

               UI_Write (Lbit, Decimal);
            end if;

         --  The test for Esize (Ent) not Uint_0 here is an annoying special
         --  case. Officially a value of zero for Esize means unknown, but
         --  here we use the fact that we know that gigi annotates Esize with
         --  No_Uint, not Uint_0. Really everyone should use No_Uint???

         elsif List_Representation_Info < 3
           or else (Esize (Ent) /= Uint_0 and then Unknown_Esize (Ent))
         then
            Write_Unknown_Val;

         --  List_Representation >= 3 and Known_Esize (Ent)

         else
            Write_Val (Esiz, Paren => not List_Representation_Info_To_JSON);

            --  If in front-end layout mode, then dynamic size is stored in
            --  storage units, so renormalize for output.

            if not Back_End_Layout then
               Write_Str (" * ");
               Write_Int (SSU);
            end if;

            --  Add appropriate first bit offset

            if not List_Representation_Info_To_JSON then
               if Sbit = 0 then
                  Write_Str (" - 1");

               elsif Sbit = 1 then
                  null;

               else
                  Write_Str (" + ");
                  Write_Int (UI_To_Int (Sbit) - 1);
               end if;
            end if;
         end if;

         if List_Representation_Info_To_JSON then
            Write_Eol;
            Spaces (Indent);
            Write_Str ("    }");
         else
            Write_Line (";");
         end if;

         --  The type is relevant for a component

         if List_Representation_Info = 4 and then Is_Itype (Etype (Ent)) then
            Relevant_Entities.Set (Etype (Ent), True);
         end if;
      end List_Component_Layout;

      ------------------------
      -- List_Record_Layout --
      ------------------------

      procedure List_Record_Layout
        (Ent                : Entity_Id;
         Starting_Position  : Uint := Uint_0;
         Starting_First_Bit : Uint := Uint_0;
         Prefix             : String := "")
      is
         Comp  : Entity_Id;
         First : Boolean := True;

      begin
         Comp := First_Component_Or_Discriminant (Ent);
         while Present (Comp) loop

            --  Skip discriminant in unchecked union (since it is not there!)

            if Ekind (Comp) = E_Discriminant
              and then Is_Unchecked_Union (Ent)
            then
               goto Continue;
            end if;

            --  Skip _Parent component in extension (to avoid overlap)

            if Chars (Comp) = Name_uParent then
               goto Continue;
            end if;

            --  All other cases

            declare
               Ctyp : constant Entity_Id := Underlying_Type (Etype (Comp));
               Npos : constant Uint      := Normalized_Position (Comp);
               Fbit : constant Uint      := Normalized_First_Bit (Comp);
               Spos : Uint;
               Sbit : Uint;

            begin
               Get_Decoded_Name_String (Chars (Comp));
               Set_Casing (Unit_Casing);

               --  If extended information is requested, recurse fully into
               --  record components, i.e. skip the outer level.

               if List_Representation_Info_Extended
                 and then Is_Record_Type (Ctyp)
                 and then Known_Static_Normalized_Position (Comp)
                 and then Known_Static_Normalized_First_Bit (Comp)
               then
                  Spos := Starting_Position  + Npos;
                  Sbit := Starting_First_Bit + Fbit;

                  if Sbit >= SSU then
                     Spos := Spos + 1;
                     Sbit := Sbit - SSU;
                  end if;

                  List_Record_Layout (Ctyp,
                    Spos, Sbit, Prefix & Name_Buffer (1 .. Name_Len) & ".");

                  goto Continue;
               end if;

               if List_Representation_Info_To_JSON then
                  if First then
                     Write_Eol;
                     First := False;
                  else
                     Write_Line (",");
                  end if;
               end if;

               List_Component_Layout (Comp,
                 Starting_Position, Starting_First_Bit, Prefix);
            end;

         <<Continue>>
            Next_Component_Or_Discriminant (Comp);
         end loop;
      end List_Record_Layout;

      -----------------------------------
      -- List_Structural_Record_Layout --
      -----------------------------------

      procedure List_Structural_Record_Layout
        (Ent       : Entity_Id;
         Outer_Ent : Entity_Id;
         Variant   : Node_Id := Empty;
         Indent    : Natural := 0)
      is
         function Derived_Discriminant (Disc : Entity_Id) return Entity_Id;
         --  This function assumes that Outer_Ent is an extension of Ent.
         --  Disc is a discriminant of Ent that does not itself constrain a
         --  discriminant of the parent type of Ent. Return the discriminant
         --  of Outer_Ent that ultimately constrains Disc, if any.

         ----------------------------
         --  Derived_Discriminant  --
         ----------------------------

         function Derived_Discriminant (Disc : Entity_Id) return Entity_Id is
            Corr_Disc    : Entity_Id;
            Derived_Disc : Entity_Id;

         begin
            Derived_Disc := First_Stored_Discriminant (Outer_Ent);

            --  Loop over the discriminants of the extension

            while Present (Derived_Disc) loop

               --  Check if this discriminant constrains another discriminant.
               --  If so, find the ultimately constrained discriminant and
               --  compare with the original components in the base type.

               if Present (Corresponding_Discriminant (Derived_Disc)) then
                  Corr_Disc := Corresponding_Discriminant (Derived_Disc);

                  while Present (Corresponding_Discriminant (Corr_Disc)) loop
                     Corr_Disc := Corresponding_Discriminant (Corr_Disc);
                  end loop;

                  if Original_Record_Component (Corr_Disc) =
                     Original_Record_Component (Disc)
                  then
                     return Derived_Disc;
                  end if;
               end if;

               Next_Stored_Discriminant (Derived_Disc);
            end loop;

            --  Disc is not constrained by a discriminant of Outer_Ent

            return Empty;
         end Derived_Discriminant;

         --  Local declarations

         Comp       : Node_Id;
         Comp_List  : Node_Id;
         First      : Boolean := True;
         Var        : Node_Id;

      --  Start of processing for List_Structural_Record_Layout

      begin
         --  If we are dealing with a variant, just process the components

         if Present (Variant) then
            Comp_List := Component_List (Variant);

         --  Otherwise, we are dealing with the full record and need to get
         --  to its definition in order to retrieve its structural layout.

         else
            declare
               Definition : Node_Id :=
                              Type_Definition (Declaration_Node (Ent));

               Is_Extension : constant Boolean :=
                                Is_Tagged_Type (Ent)
                                  and then Nkind (Definition) =
                                             N_Derived_Type_Definition;

               Disc        : Entity_Id;
               Listed_Disc : Entity_Id;
               Parent_Type : Entity_Id;

            begin
               --  If this is an extension, first list the layout of the parent
               --  and then proceed to the extension part, if any.

               if Is_Extension then
                  Parent_Type := Parent_Subtype (Ent);
                  if No (Parent_Type) then
                     raise Incomplete_Layout;
                  end if;

                  if Is_Private_Type (Parent_Type) then
                     Parent_Type := Full_View (Parent_Type);
                     pragma Assert (Present (Parent_Type));
                  end if;

                  Parent_Type := Base_Type (Parent_Type);
                  if not In_Extended_Main_Source_Unit (Parent_Type) then
                     raise Not_In_Extended_Main;
                  end if;

                  List_Structural_Record_Layout (Parent_Type, Outer_Ent);
                  First := False;

                  if Present (Record_Extension_Part (Definition)) then
                     Definition := Record_Extension_Part (Definition);
                  end if;
               end if;

               --  If the record has discriminants and is not an unchecked
               --  union, then display them now.

               if Has_Discriminants (Ent)
                 and then not Is_Unchecked_Union (Ent)
               then
                  Disc := First_Stored_Discriminant (Ent);
                  while Present (Disc) loop

                     --  If this is a record extension and the discriminant is
                     --  the renaming of another discriminant, skip it.

                     if Is_Extension
                       and then Present (Corresponding_Discriminant (Disc))
                     then
                        goto Continue_Disc;
                     end if;

                     --  If this is the parent type of an extension, retrieve
                     --  the derived discriminant from the extension, if any.

                     if Ent /= Outer_Ent then
                        Listed_Disc := Derived_Discriminant (Disc);

                        if No (Listed_Disc) then
                           goto Continue_Disc;
                        end if;
                     else
                        Listed_Disc := Disc;
                     end if;

                     Get_Decoded_Name_String (Chars (Listed_Disc));
                     Set_Casing (Unit_Casing);

                     if First then
                        Write_Eol;
                        First := False;
                     else
                        Write_Line (",");
                     end if;

                     List_Component_Layout (Listed_Disc, Indent => Indent);

                  <<Continue_Disc>>
                     Next_Stored_Discriminant (Disc);
                  end loop;
               end if;

               Comp_List := Component_List (Definition);
            end;
         end if;

         --  Bail out for the null record

         if No (Comp_List) then
            return;
         end if;

         --  Now deal with the regular components, if any

         if Present (Component_Items (Comp_List)) then
            Comp := First_Non_Pragma (Component_Items (Comp_List));
            while Present (Comp) loop

               --  Skip _Parent component in extension (to avoid overlap)

               if Chars (Defining_Identifier (Comp)) = Name_uParent then
                  goto Continue_Comp;
               end if;

               Get_Decoded_Name_String (Chars (Defining_Identifier (Comp)));
               Set_Casing (Unit_Casing);

               if First then
                  Write_Eol;
                  First := False;
               else
                  Write_Line (",");
               end if;

               List_Component_Layout
                 (Defining_Identifier (Comp), Indent => Indent);

            <<Continue_Comp>>
               Next_Non_Pragma (Comp);
            end loop;
         end if;

         --  We are done if there is no variant part

         if No (Variant_Part (Comp_List)) then
            return;
         end if;

         Write_Eol;
         Spaces (Indent);
         Write_Line ("  ],");
         Spaces (Indent);
         Write_Str ("  ""variant"" : [");

         --  Otherwise we recurse on each variant

         Var := First_Non_Pragma (Variants (Variant_Part (Comp_List)));
         First := True;
         while Present (Var) loop
            if First then
               Write_Eol;
               First := False;
            else
               Write_Line (",");
            end if;

            Spaces (Indent);
            Write_Line ("    {");
            Spaces (Indent);
            Write_Str ("      ""present"": ");
            Write_Val (Present_Expr (Var));
            Write_Line (",");
            Spaces (Indent);
            Write_Str ("      ""record"": [");

            List_Structural_Record_Layout (Ent, Outer_Ent, Var, Indent + 4);

            Write_Eol;
            Spaces (Indent);
            Write_Line ("      ]");
            Spaces (Indent);
            Write_Str ("    }");
            Next_Non_Pragma (Var);
         end loop;
      end List_Structural_Record_Layout;

   --  Start of processing for List_Record_Info

   begin
      Write_Separator;

      if List_Representation_Info_To_JSON then
         Write_Line ("{");
      end if;

      List_Common_Type_Info (Ent);

      --  First find out max line length and max starting position
      --  length, for the purpose of lining things up nicely.

      Compute_Max_Length (Ent);

      --  Then do actual output based on those values

      if List_Representation_Info_To_JSON then
         Write_Line (",");
         Write_Str ("  ""record"": [");

         --  ??? We can output structural layout only for base types fully
         --  declared in the extended main source unit for the time being,
         --  because otherwise declarations might not be processed at all.

         if Is_Base_Type (Ent) then
            begin
               List_Structural_Record_Layout (Ent, Ent);

            exception
               when Incomplete_Layout
                  | Not_In_Extended_Main
               =>
                  List_Record_Layout (Ent);

               when others =>
                  raise Program_Error;
            end;
         else
            List_Record_Layout (Ent);
         end if;

         Write_Eol;
         Write_Str ("  ]");
      else
         Write_Str ("for ");
         List_Name (Ent);
         Write_Line (" use record");

         List_Record_Layout (Ent);

         Write_Line ("end record;");
      end if;

      List_Scalar_Storage_Order (Ent, Bytes_Big_Endian);

      List_Linker_Section (Ent);

      if List_Representation_Info_To_JSON then
         Write_Eol;
         Write_Line ("}");
      end if;

      --  The type is relevant for a record subtype

      if List_Representation_Info = 4
        and then not Is_Base_Type (Ent)
        and then Is_Itype (Etype (Ent))
      then
         Relevant_Entities.Set (Etype (Ent), True);
      end if;
   end List_Record_Info;

   -------------------
   -- List_Rep_Info --
   -------------------

   procedure List_Rep_Info (Bytes_Big_Endian : Boolean) is
      Col : Nat;

   begin
      if List_Representation_Info /= 0
        or else List_Representation_Info_Mechanisms
      then
         --  For the normal case, we output a single JSON stream

         if not List_Representation_Info_To_File
           and then List_Representation_Info_To_JSON
         then
            Write_Line ("[");
            Need_Separator := False;
         end if;

         for U in Main_Unit .. Last_Unit loop
            if In_Extended_Main_Source_Unit (Cunit_Entity (U)) then
               Unit_Casing := Identifier_Casing (Source_Index (U));

               if List_Representation_Info = 4 then
                  Relevant_Entities.Reset;
               end if;

               --  Normal case, list to standard output

               if not List_Representation_Info_To_File then
                  if not List_Representation_Info_To_JSON then
                     Write_Eol;
                     Write_Str ("Representation information for unit ");
                     Write_Unit_Name (Unit_Name (U));
                     Col := Column;
                     Write_Eol;

                     for J in 1 .. Col - 1 loop
                        Write_Char ('-');
                     end loop;

                     Write_Eol;
                     Need_Separator := True;
                  end if;

                  List_Entities (Cunit_Entity (U), Bytes_Big_Endian);

               --  List representation information to file

               else
                  Create_Repinfo_File_Access.all
                    (Get_Name_String (File_Name (Source_Index (U))));
                  Set_Special_Output (Write_Info_Line'Access);
                  if List_Representation_Info_To_JSON then
                     Write_Line ("[");
                  end if;
                  Need_Separator := False;
                  List_Entities (Cunit_Entity (U), Bytes_Big_Endian);
                  if List_Representation_Info_To_JSON then
                     Write_Line ("]");
                  end if;
                  Cancel_Special_Output;
                  Close_Repinfo_File_Access.all;
               end if;
            end if;
         end loop;

         if not List_Representation_Info_To_File
           and then List_Representation_Info_To_JSON
         then
            Write_Line ("]");
         end if;
      end if;
   end List_Rep_Info;

   -------------------------------
   -- List_Scalar_Storage_Order --
   -------------------------------

   procedure List_Scalar_Storage_Order
     (Ent              : Entity_Id;
      Bytes_Big_Endian : Boolean)
   is
      procedure List_Attr (Attr_Name : String; Is_Reversed : Boolean);
      --  Show attribute definition clause for Attr_Name (an endianness
      --  attribute), depending on whether or not the endianness is reversed
      --  compared to native endianness.

      ---------------
      -- List_Attr --
      ---------------

      procedure List_Attr (Attr_Name : String; Is_Reversed : Boolean) is
      begin
         if List_Representation_Info_To_JSON then
            Write_Line (",");
            Write_Str ("  """);
            Write_Str (Attr_Name);
            Write_Str (""": ""System.");
         else
            Write_Str ("for ");
            List_Name (Ent);
            Write_Char (''');
            Write_Str (Attr_Name);
            Write_Str (" use System.");
         end if;

         if Bytes_Big_Endian xor Is_Reversed then
            Write_Str ("High");
         else
            Write_Str ("Low");
         end if;

         Write_Str ("_Order_First");
         if List_Representation_Info_To_JSON then
            Write_Str ("""");
         else
            Write_Line (";");
         end if;
      end List_Attr;

      List_SSO : constant Boolean :=
                   Has_Rep_Item (Ent, Name_Scalar_Storage_Order)
                     or else SSO_Set_Low_By_Default  (Ent)
                     or else SSO_Set_High_By_Default (Ent);
      --  Scalar_Storage_Order is displayed if specified explicitly or set by
      --  Default_Scalar_Storage_Order.

   --  Start of processing for List_Scalar_Storage_Order

   begin
      --  For record types, list Bit_Order if not default, or if SSO is shown

      --  Also, when -gnatR4 is in effect always list bit order and scalar
      --  storage order explicitly, so that you don't need to know the native
      --  endianness of the target for which the output was produced in order
      --  to interpret it.

      if Is_Record_Type (Ent)
        and then (List_SSO
                   or else Reverse_Bit_Order (Ent)
                   or else List_Representation_Info = 4)
      then
         List_Attr ("Bit_Order", Reverse_Bit_Order (Ent));
      end if;

      --  List SSO if required. If not, then storage is supposed to be in
      --  native order.

      if List_SSO or else List_Representation_Info = 4 then
         List_Attr ("Scalar_Storage_Order", Reverse_Storage_Order (Ent));
      else
         pragma Assert (not Reverse_Storage_Order (Ent));
         null;
      end if;
   end List_Scalar_Storage_Order;

   --------------------------
   -- List_Subprogram_Info --
   --------------------------

   procedure List_Subprogram_Info (Ent : Entity_Id) is
      First : Boolean := True;
      Plen  : Natural;
      Form  : Entity_Id;

   begin
      Write_Separator;

      if List_Representation_Info_To_JSON then
         Write_Line ("{");
         Write_Str ("  ""name"": """);
         List_Name (Ent);
         Write_Line (""",");
         List_Location (Ent);

         Write_Str ("  ""Convention"": """);
      else
         case Ekind (Ent) is
            when E_Function =>
               Write_Str ("function ");

            when E_Operator =>
               Write_Str ("operator ");

            when E_Procedure =>
               Write_Str ("procedure ");

            when E_Subprogram_Type =>
               Write_Str ("type ");

            when E_Entry
               | E_Entry_Family
            =>
               Write_Str ("entry ");

            when others =>
               raise Program_Error;
         end case;

         List_Name (Ent);
         Write_Str (" declared at ");
         Write_Location (Sloc (Ent));
         Write_Eol;

         Write_Str ("convention : ");
      end if;

      case Convention (Ent) is
         when Convention_Ada =>
            Write_Str ("Ada");

         when Convention_Ada_Pass_By_Copy =>
            Write_Str ("Ada_Pass_By_Copy");

         when Convention_Ada_Pass_By_Reference =>
            Write_Str ("Ada_Pass_By_Reference");

         when Convention_Intrinsic =>
            Write_Str ("Intrinsic");

         when Convention_Entry =>
            Write_Str ("Entry");

         when Convention_Protected =>
            Write_Str ("Protected");

         when Convention_Assembler =>
            Write_Str ("Assembler");

         when Convention_C =>
            Write_Str ("C");

         when Convention_COBOL =>
            Write_Str ("COBOL");

         when Convention_CPP =>
            Write_Str ("C++");

         when Convention_Fortran =>
            Write_Str ("Fortran");

         when Convention_Stdcall =>
            Write_Str ("Stdcall");

         when Convention_Stubbed =>
            Write_Str ("Stubbed");
      end case;

      if List_Representation_Info_To_JSON then
         Write_Line (""",");
         Write_Str ("  ""formal"": [");
      else
         Write_Eol;
      end if;

      --  Find max length of formal name

      Plen := 0;
      Form := First_Formal (Ent);
      while Present (Form) loop
         Get_Unqualified_Decoded_Name_String (Chars (Form));

         if Name_Len > Plen then
            Plen := Name_Len;
         end if;

         Next_Formal (Form);
      end loop;

      --  Output formals and mechanisms

      Form := First_Formal (Ent);
      while Present (Form) loop
         Get_Unqualified_Decoded_Name_String (Chars (Form));
         Set_Casing (Unit_Casing);

         if List_Representation_Info_To_JSON then
            if First then
               Write_Eol;
               First := False;
            else
               Write_Line (",");
            end if;

            Write_Line ("    {");
            Write_Str ("      ""name"": """);
            Write_Str (Name_Buffer (1 .. Name_Len));
            Write_Line (""",");

            Write_Str ("      ""mechanism"": """);
            Write_Mechanism (Mechanism (Form));
            Write_Line ("""");
            Write_Str ("    }");
         else
            while Name_Len <= Plen loop
               Name_Len := Name_Len + 1;
               Name_Buffer (Name_Len) := ' ';
            end loop;

            Write_Str ("   ");
            Write_Str (Name_Buffer (1 .. Plen + 1));
            Write_Str (": passed by ");

            Write_Mechanism (Mechanism (Form));
            Write_Eol;
         end if;

         Next_Formal (Form);
      end loop;

      if List_Representation_Info_To_JSON then
         Write_Eol;
         Write_Str ("  ]");
      end if;

      if Ekind (Ent) = E_Function then
         if List_Representation_Info_To_JSON then
            Write_Line (",");
            Write_Str ("  ""mechanism"": """);
            Write_Mechanism (Mechanism (Ent));
            Write_Str ("""");
         else
            Write_Str ("returns by ");
            Write_Mechanism (Mechanism (Ent));
            Write_Eol;
         end if;
      end if;

      if not Is_Entry (Ent) then
         List_Linker_Section (Ent);
      end if;

      if List_Representation_Info_To_JSON then
         Write_Eol;
         Write_Line ("}");
      end if;
   end List_Subprogram_Info;

   --------------------
   -- List_Type_Info --
   --------------------

   procedure List_Type_Info (Ent : Entity_Id) is
   begin
      Write_Separator;

      if List_Representation_Info_To_JSON then
         Write_Line ("{");
      end if;

      List_Common_Type_Info (Ent);

      --  Special stuff for fixed-point

      if Is_Fixed_Point_Type (Ent) then

         --  Write small (always a static constant)

         if List_Representation_Info_To_JSON then
            Write_Line (",");
            Write_Str ("  ""Small"": ");
            UR_Write (Small_Value (Ent));
         else
            Write_Str ("for ");
            List_Name (Ent);
            Write_Str ("'Small use ");
            UR_Write (Small_Value (Ent));
            Write_Line (";");
         end if;

         --  Write range if static

         declare
            R : constant Node_Id := Scalar_Range (Ent);

         begin
            if Nkind (Low_Bound (R)) = N_Real_Literal
                 and then
               Nkind (High_Bound (R)) = N_Real_Literal
            then
               if List_Representation_Info_To_JSON then
                  Write_Line (",");
                  Write_Str ("  ""Range"": [ ");
                  UR_Write (Realval (Low_Bound (R)));
                  Write_Str (", ");
                  UR_Write (Realval (High_Bound (R)));
                  Write_Str (" ]");
               else
                  Write_Str ("for ");
                  List_Name (Ent);
                  Write_Str ("'Range use ");
                  UR_Write (Realval (Low_Bound (R)));
                  Write_Str (" .. ");
                  UR_Write (Realval (High_Bound (R)));
                  Write_Line (";");
               end if;
            end if;
         end;
      end if;

      List_Linker_Section (Ent);

      if List_Representation_Info_To_JSON then
         Write_Eol;
         Write_Line ("}");
      end if;
   end List_Type_Info;

   ----------------------
   -- Rep_Not_Constant --
   ----------------------

   function Rep_Not_Constant (Val : Node_Ref_Or_Val) return Boolean is
   begin
      if Val = No_Uint or else Val < 0 then
         return True;
      else
         return False;
      end if;
   end Rep_Not_Constant;

   ---------------
   -- Rep_Value --
   ---------------

   function Rep_Value (Val : Node_Ref_Or_Val; D : Discrim_List) return Uint is

      function B (Val : Boolean) return Uint;
      --  Returns Uint_0 for False, Uint_1 for True

      function T (Val : Node_Ref_Or_Val) return Boolean;
      --  Returns True for 0, False for any non-zero (i.e. True)

      function V (Val : Node_Ref_Or_Val) return Uint;
      --  Internal recursive routine to evaluate tree

      function W (Val : Uint) return Word;
      --  Convert Val to Word, assuming Val is always in the Int range. This
      --  is a helper function for the evaluation of bitwise expressions like
      --  Bit_And_Expr, for which there is no direct support in uintp. Uint
      --  values out of the Int range are expected to be seen in such
      --  expressions only with overflowing byte sizes around, introducing
      --  inherent unreliabilities in computations anyway.

      -------
      -- B --
      -------

      function B (Val : Boolean) return Uint is
      begin
         if Val then
            return Uint_1;
         else
            return Uint_0;
         end if;
      end B;

      -------
      -- T --
      -------

      function T (Val : Node_Ref_Or_Val) return Boolean is
      begin
         if V (Val) = 0 then
            return False;
         else
            return True;
         end if;
      end T;

      -------
      -- V --
      -------

      function V (Val : Node_Ref_Or_Val) return Uint is
         L, R, Q : Uint;

      begin
         if Val >= 0 then
            return Val;

         else
            declare
               Node : Exp_Node renames Rep_Table.Table (-UI_To_Int (Val));

            begin
               case Node.Expr is
                  when Cond_Expr =>
                     if T (Node.Op1) then
                        return V (Node.Op2);
                     else
                        return V (Node.Op3);
                     end if;

                  when Plus_Expr =>
                     return V (Node.Op1) + V (Node.Op2);

                  when Minus_Expr =>
                     return V (Node.Op1) - V (Node.Op2);

                  when Mult_Expr =>
                     return V (Node.Op1) * V (Node.Op2);

                  when Trunc_Div_Expr =>
                     return V (Node.Op1) / V (Node.Op2);

                  when Ceil_Div_Expr =>
                     return
                       UR_Ceiling
                         (V (Node.Op1) / UR_From_Uint (V (Node.Op2)));

                  when Floor_Div_Expr =>
                     return
                       UR_Floor
                         (V (Node.Op1) / UR_From_Uint (V (Node.Op2)));

                  when Trunc_Mod_Expr =>
                     return V (Node.Op1) rem V (Node.Op2);

                  when Floor_Mod_Expr =>
                     return V (Node.Op1) mod V (Node.Op2);

                  when Ceil_Mod_Expr =>
                     L := V (Node.Op1);
                     R := V (Node.Op2);
                     Q := UR_Ceiling (L / UR_From_Uint (R));
                     return L - R * Q;

                  when Exact_Div_Expr =>
                     return V (Node.Op1) / V (Node.Op2);

                  when Negate_Expr =>
                     return -V (Node.Op1);

                  when Min_Expr =>
                     return UI_Min (V (Node.Op1), V (Node.Op2));

                  when Max_Expr =>
                     return UI_Max (V (Node.Op1), V (Node.Op2));

                  when Abs_Expr =>
                     return UI_Abs (V (Node.Op1));

                  when Truth_And_Expr =>
                     return B (T (Node.Op1) and then T (Node.Op2));

                  when Truth_Or_Expr =>
                     return B (T (Node.Op1) or else T (Node.Op2));

                  when Truth_Xor_Expr =>
                     return B (T (Node.Op1) xor T (Node.Op2));

                  when Truth_Not_Expr =>
                     return B (not T (Node.Op1));

                  when Bit_And_Expr =>
                     L := V (Node.Op1);
                     R := V (Node.Op2);
                     return UI_From_Int (Int (W (L) and W (R)));

                  when Lt_Expr =>
                     return B (V (Node.Op1) < V (Node.Op2));

                  when Le_Expr =>
                     return B (V (Node.Op1) <= V (Node.Op2));

                  when Gt_Expr =>
                     return B (V (Node.Op1) > V (Node.Op2));

                  when Ge_Expr =>
                     return B (V (Node.Op1) >= V (Node.Op2));

                  when Eq_Expr =>
                     return B (V (Node.Op1) = V (Node.Op2));

                  when Ne_Expr =>
                     return B (V (Node.Op1) /= V (Node.Op2));

                  when Discrim_Val =>
                     declare
                        Sub : constant Int := UI_To_Int (Node.Op1);
                     begin
                        pragma Assert (Sub in D'Range);
                        return D (Sub);
                     end;

                  when Dynamic_Val =>
                     return No_Uint;
               end case;
            end;
         end if;
      end V;

      -------
      -- W --
      -------

      --  We use an unchecked conversion to map Int values to their Word
      --  bitwise equivalent, which we could not achieve with a normal type
      --  conversion for negative Ints. We want bitwise equivalents because W
      --  is used as a helper for bit operators like Bit_And_Expr, and can be
      --  called for negative Ints in the context of aligning expressions like
      --  X+Align & -Align.

      function W (Val : Uint) return Word is
         function To_Word is new Ada.Unchecked_Conversion (Int, Word);
      begin
         return To_Word (UI_To_Int (Val));
      end W;

   --  Start of processing for Rep_Value

   begin
      if Val = No_Uint then
         return No_Uint;

      else
         return V (Val);
      end if;
   end Rep_Value;

   ------------
   -- Spaces --
   ------------

   procedure Spaces (N : Natural) is
   begin
      for J in 1 .. N loop
         Write_Char (' ');
      end loop;
   end Spaces;

   ---------------------
   -- Write_Info_Line --
   ---------------------

   procedure Write_Info_Line (S : String) is
   begin
      Write_Repinfo_Line_Access.all (S (S'First .. S'Last - 1));
   end Write_Info_Line;

   ---------------------
   -- Write_Mechanism --
   ---------------------

   procedure Write_Mechanism (M : Mechanism_Type) is
   begin
      case M is
         when 0 =>
            Write_Str ("default");

         when -1 =>
            Write_Str ("copy");

         when -2 =>
            Write_Str ("reference");

         when others =>
            raise Program_Error;
      end case;
   end Write_Mechanism;

   ---------------------
   -- Write_Separator --
   ---------------------

   procedure Write_Separator is
   begin
      if Need_Separator then
         if List_Representation_Info_To_JSON then
            Write_Line (",");
         else
            Write_Eol;
         end if;
      else
         Need_Separator := True;
      end if;
   end Write_Separator;

   -----------------------
   -- Write_Unknown_Val --
   -----------------------

   procedure Write_Unknown_Val is
   begin
      if List_Representation_Info_To_JSON then
         Write_Str ("""??""");
      else
         Write_Str ("??");
      end if;
   end Write_Unknown_Val;

   ---------------
   -- Write_Val --
   ---------------

   procedure Write_Val (Val : Node_Ref_Or_Val; Paren : Boolean := False) is
   begin
      if Rep_Not_Constant (Val) then
         if List_Representation_Info < 3 or else Val = No_Uint then
            Write_Unknown_Val;

         else
            if Paren then
               Write_Char ('(');
            end if;

            if Back_End_Layout then
               List_GCC_Expression (Val);
            else
               Write_Name_Decoded (Chars (Get_Dynamic_SO_Entity (Val)));
            end if;

            if Paren then
               Write_Char (')');
            end if;
         end if;

      else
         UI_Write (Val, Decimal);
      end if;
   end Write_Val;

end Repinfo;