doc/getting/mcode.rst


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

.. _BUILD:mcode:

mcode backend
#############

The mcode backend is available for all supported platforms and is also the
simplest procedure, because it requires the fewest dependencies and configuration
options.

.. _BUILD:mcode:GNAT:

GCC/GNAT: GNU/Linux or Windows (MinGW/MSYS2)
============================================

.. rubric:: Requirements

* GCC (Gnu Compiler Collection)
* GNAT (Ada compiler for GCC)

GHDL is configured by ``configure`` and built by ``make``.

* First, GHDL needs to be configured. It is common to specify a ``PREFIX``
  (installation directory like ``/usr/local`` or ``/opt/ghdl``). Without any
  other option, ``configure`` selects `mcode` as the backend.

* Next, ``make`` starts the compilation process.

* Finally, ``make install`` installs GHDL into the installation directory
  specified by ``PREFIX``.

.. HINT :: ON GNU/Linux, you may need super user privileges (``sudo ...``).


.. rubric:: Example:

.. code-block:: Bash

   $ cd <ghdl>
   $ mkdir build
   $ cd build
   $ ../configure --prefix=PREFIX
   $ make
   $ make install

.. _BUILD:mcode:GNATGPL-Windows:

GNAT GPL: Windows
=================

.. rubric:: Requirements

* GNAT GPL from http://libre.adacore.com
* PowerShell 4
* PowerShell Community Extensions (PSCX)

.. rubric:: `compile.ps1`

.. code-block::

   Commands          Description
   --------------------------------------------------------------------
   -Help             Display the integrated help pages
   -Clean            Clean up all files and directories
   -Compile          Compile GHDL
   -Install          Install all files into a directory (xcopy deployment)
   -Uninstall        Uninstall all files from a directory
   -Update           Update files in the installation directory
   -CreatePackage    create an installer package

   Install options:
   -InstallPath      Installation directory

   CreatePackage options:
   -Zip              Create a zip-file for xcopy deployment
--  Package (and subprograms) instantiations

--  When a package is instantiated, we need to 'duplicate' its declaration.
--  This looks useless for analysis but it isn't: a type from a package
--  instantiated twice declares two different types.  Without duplication, we
--  need to attach to each declaration its instance, which looks more expansive
--  that duplicating the declaration.
--
--  Furthermore, for generic type interface, it looks a good idea to duplicate
--  the body (macro expansion).
--
--  Duplicating is not trivial: internal links must be kept and external
--  links preserved.  A table is used to map nodes from the uninstantiated
--  package to its duplicated node.  Links from instantiated declaration to
--  the original declaration are also stored in that table.

with Tables;
with Vhdl.Nodes_Priv;
with Vhdl.Nodes_Meta;
with Types; use Types;
with Files_Map;
with Vhdl.Utils; use Vhdl.Utils;
with Vhdl.Errors; use Vhdl.Errors;
with Vhdl.Sem_Utils;

package body Vhdl.Sem_Inst is
   --  Table of origin.  This is an extension of vhdl nodes to track the
   --  origin of a node.  If a node has a non-null origin, then the node was
   --  instantiated for the origin node.
   --
   --  Furthermore, during instantiation, we need to keep track of instantiated
   --  nodes (ie nodes created by instantiation) used by references.  As an
   --  instance cannot be uninstantiated, there is no collisions, as soon as
   --  such entries are cleaned after instantiation.
   --
   --  As an example, here are declarations of an uninstantiated package:
   --    type Nat is range 0 to 1023;
   --    constant N : Nat := 5;
   --  A node Nat1 will be created from node Nat (an integer type definition).
   --  The origin of Nat1 is Nat and this is true forever.  During
   --  instantiation, the instance of Nat is Nat1, so that the type of N will
   --  be set to Nat1.
   package Origin_Table is new Tables
     (Table_Component_Type => Iir,
      Table_Index_Type => Iir,
      Table_Low_Bound => 2,
      Table_Initial => 1024);

   procedure Expand_Origin_Table
   is
      use Vhdl.Nodes_Priv;
      Last : constant Iir := Nodes.Get_Last_Node;
      El : constant Iir := Origin_Table.Last;
   begin
      if El < Last then
         Origin_Table.Set_Last (Last);
         Origin_Table.Table (El + 1 .. Last) := (others => Null_Iir);
      end if;
   end Expand_Origin_Table;

   --  This is the public function; the table may not have been extended.
   function Get_Origin (N : Iir) return Iir
   is
      --  Make the '<=' operator visible.
      use Vhdl.Nodes_Priv;
   begin
      if N <= Origin_Table.Last then
         return Origin_Table.Table (N);
      else
         return Null_Iir;
      end if;
   end Get_Origin;

   --  This is the private function: the table *must* have been extended.
   function Get_Instance (N : Iir) return Iir
   is
      --  Make '<=' operator visible for the assert.
      use Vhdl.Nodes_Priv;
   begin
      pragma Assert (N <= Origin_Table.Last);
      return Origin_Table.Table (N);
   end Get_Instance;

   procedure Set_Origin (N : Iir; Orig : Iir) is
   begin
      --  As nodes are created, we need to expand origin table.
      Expand_Origin_Table;

      pragma Assert (Orig = Null_Iir
                       or else Origin_Table.Table (N) = Null_Iir);
      Origin_Table.Table (N) := Orig;
   end Set_Origin;

   type Instance_Entry_Type is record
      --  Node
      N : Iir;

      --  Old value in Origin_Table.
      Old_Origin : Iir;
   end record;

   type Instance_Index_Type is new Natural;

   --  Table of previous values in Origin_Table.  The first purpose of this
   --  table is to be able to revert the calls to Set_Instance, so that a unit
   --  can be instantiated several times.  Keeping the nodes that have been
   --  instantiated is cheaper than walking the tree a second time.
   --  The second purpose of this table is to be able to have uninstantiated
   --  packages in instantiated packages.  In that case, the slot in
   --  Origin_Table cannot be the origin and the instance at the same time and
   --  has to be saved.
   package Prev_Instance_Table is new Tables
     (Table_Component_Type => Instance_Entry_Type,
      Table_Index_Type => Instance_Index_Type,
      Table_Low_Bound => 1,
      Table_Initial => 256);

   --  The instance of ORIG is now N.  So during instantiation, a reference
   --  to ORIG will be replaced by a reference to N.  The previous instance
   --  of ORIG is saved.
   procedure Set_Instance (Orig : Iir; N : Iir)
   is
      use Vhdl.Nodes_Priv;
   begin
      pragma Assert (Orig <= Origin_Table.Last);

      --  Save the old entry
      Prev_Instance_Table.Append
        (Instance_Entry_Type'(N => Orig,
                              Old_Origin => Origin_Table.Table (Orig)));

      --  Set the entry.
      Origin_Table.Table (Orig) := N;
   end Set_Instance;

   procedure Restore_Origin (Mark : Instance_Index_Type) is
   begin
      for I in reverse Mark + 1 .. Prev_Instance_Table.Last loop
         declare
            El : Instance_Entry_Type renames Prev_Instance_Table.Table (I);
         begin
            Origin_Table.Table (El.N) := El.Old_Origin;
         end;
      end loop;
      Prev_Instance_Table.Set_Last (Mark);
   end Restore_Origin;

   --  The virtual file for the instance.
   Instance_File : Source_File_Entry;

   --  True if currently instantiated a shared generic.
   Is_Within_Shared_Instance : Boolean := False;

   --  Get the new location.
   function Relocate (Loc : Location_Type) return Location_Type is
   begin
      if Instance_File /= No_Source_File_Entry then
         --  For Instantiate.
         return Files_Map.Instance_Relocate (Instance_File, Loc);
      else
         --  For Copy_Tree.
         return Loc;
      end if;
   end Relocate;

   procedure Create_Relocation (Inst : Iir; Orig : Iir)
   is
      use Files_Map;
      Orig_File : Source_File_Entry;
      Pos : Source_Ptr;
   begin
      Location_To_File_Pos (Get_Location (Orig), Orig_File, Pos);
      Instance_File := Create_Instance_Source_File
        (Orig_File, Get_Location (Inst), Inst);
   end Create_Relocation;

   function Instantiate_Iir (N : Iir; Is_Ref : Boolean) return Iir;

   --  Instantiate a list.  Simply create a new list and instantiate nodes of
   --  that list.
   function Instantiate_Iir_List (L : Iir_List; Is_Ref : Boolean)
                                 return Iir_List
   is
      Res : Iir_List;
      It : List_Iterator;
      El : Iir;
   begin
      case L is
         when Null_Iir_List
           | Iir_List_All =>
            return L;
         when others =>
            Res := Create_Iir_List;
            It := List_Iterate (L);
            while Is_Valid (It) loop
               El := Get_Element (It);
               Append_Element (Res, Instantiate_Iir (El, Is_Ref));
               Next (It);
            end loop;
            return Res;
      end case;
   end Instantiate_Iir_List;

   function Instantiate_Iir_Flist (L : Iir_Flist; Is_Ref : Boolean)
                                  return Iir_Flist
   is
      Res : Iir_Flist;
      El : Iir;
   begin
      case L is
         when Null_Iir_Flist
           | Iir_Flist_All
           | Iir_Flist_Others =>
            return L;
         when others =>
            Res := Create_Iir_Flist (Get_Nbr_Elements (L));
            for I in Flist_First .. Flist_Last (L) loop
               El := Get_Nth_Element (L, I);
               Set_Nth_Element (Res, I, Instantiate_Iir (El, Is_Ref));
            end loop;
            return Res;
      end case;
   end Instantiate_Iir_Flist;

   --  Instantiate a chain.  This is a special case to reduce stack depth.
   function Instantiate_Iir_Chain (N : Iir) return Iir
   is
      First : Iir;
      Last : Iir;
      Next_N : Iir;
      Next_R : Iir;
   begin
      if N = Null_Iir then
         return Null_Iir;
      end if;

      First := Instantiate_Iir (N, False);
      Last := First;
      Next_N := Get_Chain (N);
      while Next_N /= Null_Iir loop
         Next_R := Instantiate_Iir (Next_N, False);
         Set_Chain (Last, Next_R);
         Last := Next_R;
         Next_N := Get_Chain (Next_N);
      end loop;

      return First;
   end Instantiate_Iir_Chain;

   procedure Instantiate_Iir_Field
     (Res : Iir; N : Iir; F : Nodes_Meta.Fields_Enum)
   is
      use Nodes_Meta;
   begin
      case Get_Field_Type (F) is
         when Type_Iir =>
            declare
               S : constant Iir := Get_Iir (N, F);
               R : Iir;
            begin
               case Get_Field_Attribute (F) is
                  when Attr_None =>
                     R := Instantiate_Iir (S, False);
                  when Attr_Ref =>
                     R := Instantiate_Iir (S, True);
                  when Attr_Maybe_Ref =>
                     R := Instantiate_Iir (S, Get_Is_Ref (N));
                  when Attr_Forward_Ref =>
                     --  Must be explicitely handled in Instantiate_Iir, as it
                     --  requires special handling.
                     raise Internal_Error;
                  when Attr_Maybe_Forward_Ref =>
                     if Get_Is_Forward_Ref (N) then
                        --  Likewise: must be explicitely handled.
                        raise Internal_Error;
                     else
                        R := Instantiate_Iir (S, True);
                     end if;
                  when Attr_Chain =>
                     R := Instantiate_Iir_Chain (S);
                  when Attr_Chain_Next =>
                     R := Null_Iir;
                  when Attr_Of_Ref | Attr_Of_Maybe_Ref =>
                     --  Can only appear in list.
                     raise Internal_Error;
               end case;
               Set_Iir (Res, F, R);
            end;
         when Type_Iir_List =>
            declare
               S : constant Iir_List := Get_Iir_List (N, F);
               R : Iir_List;
               Ref : Boolean;
            begin
               case Get_Field_Attribute (F) is
                  when Attr_None =>
                     Ref := False;
                  when Attr_Of_Ref =>
                     Ref := True;
                  when Attr_Of_Maybe_Ref =>
                     Ref := Get_Is_Ref (N);
                  when others =>
                     --  Ref is specially handled in Instantiate_Iir.
                     --  Others cannot appear for lists.
                     raise Internal_Error;
               end case;
               R := Instantiate_Iir_List (S, Ref);
               Set_Iir_List (Res, F, R);
            end;
         when Type_Iir_Flist =>
            declare
               S : constant Iir_Flist := Get_Iir_Flist (N, F);
               R : Iir_Flist;
               Ref : Boolean;
            begin
               case Get_Field_Attribute (F) is
                  when Attr_None =>
                     Ref := False;
                  when Attr_Of_Ref =>
                     Ref := True;
                  when Attr_Of_Maybe_Ref =>
                     Ref := Get_Is_Ref (N);
                  when others =>
                     --  Ref is specially handled in Instantiate_Iir.
                     --  Others cannot appear for lists.
                     raise Internal_Error;
               end case;
               R := Instantiate_Iir_Flist (S, Ref);
               Set_Iir_Flist (Res, F, R);
            end;
         when Type_PSL_NFA
           | Type_PSL_Node =>
            --  TODO
            raise Internal_Error;
         when Type_String8_Id =>
            Set_String8_Id (Res, F, Get_String8_Id (N, F));
         when Type_Source_Ptr =>
            Set_Source_Ptr (Res, F, Get_Source_Ptr (N, F));
         when Type_Source_File_Entry =>
            Set_Source_File_Entry (Res, F, Get_Source_File_Entry (N, F));
         when Type_Date_Type
           | Type_Date_State_Type
           | Type_Time_Stamp_Id
           | Type_File_Checksum_Id =>
            --  Can this happen ?
            raise Internal_Error;
         when Type_Number_Base_Type =>
            Set_Number_Base_Type (Res, F, Get_Number_Base_Type (N, F));
         when Type_Iir_Constraint =>
            Set_Iir_Constraint (Res, F, Get_Iir_Constraint (N, F));
         when Type_Iir_Mode =>
            Set_Iir_Mode (Res, F, Get_Iir_Mode (N, F));
         when Type_Iir_Index32 =>
            Set_Iir_Index32 (Res, F, Get_Iir_Index32 (N, F));
         when Type_Int64 =>
            Set_Int64 (Res, F, Get_Int64 (N, F));
         when Type_Boolean =>
            Set_Boolean (Res, F, Get_Boolean (N, F));
         when Type_Iir_Staticness =>
            Set_Iir_Staticness (Res, F, Get_Iir_Staticness (N, F));
         when Type_Iir_All_Sensitized =>
            Set_Iir_All_Sensitized (Res, F, Get_Iir_All_Sensitized (N, F));
         when Type_Iir_Signal_Kind =>
            Set_Iir_Signal_Kind (Res, F, Get_Iir_Signal_Kind (N, F));
         when Type_Tri_State_Type =>
            Set_Tri_State_Type (Res, F, Get_Tri_State_Type (N, F));
         when Type_Iir_Pure_State =>
            Set_Iir_Pure_State (Res, F, Get_Iir_Pure_State (N, F));
         when Type_Iir_Delay_Mechanism =>
            Set_Iir_Delay_Mechanism (Res, F, Get_Iir_Delay_Mechanism (N, F));
         when Type_Iir_Force_Mode =>
            Set_Iir_Force_Mode (Res, F, Get_Iir_Force_Mode (N, F));
         when Type_Iir_Predefined_Functions =>
            Set_Iir_Predefined_Functions
              (Res, F, Get_Iir_Predefined_Functions (N, F));
         when Type_Direction_Type =>
            Set_Direction_Type (Res, F, Get_Direction_Type (N, F));
         when Type_Iir_Int32 =>
            Set_Iir_Int32 (Res, F, Get_Iir_Int32 (N, F));
         when Type_Int32 =>
            Set_Int32 (Res, F, Get_Int32 (N, F));
         when Type_Fp64 =>
            Set_Fp64 (Res, F, Get_Fp64 (N, F));
         when Type_Token_Type =>
            Set_Token_Type (Res, F, Get_Token_Type (N, F));
         when Type_Scalar_Size =>
            Set_Scalar_Size (Res, F, Get_Scalar_Size (N, F));
         when Type_Name_Id =>
            Set_Name_Id (Res, F, Get_Name_Id (N, F));
      end case;
   end Instantiate_Iir_Field;

   --  Set designated_entity of attribute_value from attribute_value_chain
   --  of RES.
   procedure Instantiate_Attribute_Value_Chain (Res : Iir)
   is
      Val : Iir;
      Ref_Ent : Iir;
   begin
      Val := Get_Attribute_Value_Chain (Res);
      while Val /= Null_Iir loop
         pragma Assert (Get_Designated_Entity (Val) = Null_Iir);
         Ref_Ent := Get_Designated_Entity (Get_Origin (Val));
         Ref_Ent := Instantiate_Iir (Ref_Ent, True);
         Set_Designated_Entity (Val, Ref_Ent);
         Val := Get_Value_Chain (Val);
      end loop;
   end Instantiate_Attribute_Value_Chain;

   function Instantiate_Iir (N : Iir; Is_Ref : Boolean) return Iir
   is
      Res : Iir;
   begin
      --  Nothing to do for null node.
      if N = Null_Iir then
         return Null_Iir;
      end if;

      --  For a reference, do not create a new node.
      if Is_Ref then
         Res := Get_Instance (N);
         if Res /= Null_Iir then
            --  There is an instance for N.
            return Res;
         else
            --  Reference outside the instance.
            return N;
         end if;
      end if;

      declare
         use Nodes_Meta;
         Kind : constant Iir_Kind := Get_Kind (N);
         Fields : constant Fields_Array := Get_Fields (Kind);
         F : Fields_Enum;
      begin
         --  In general, Get_Instance (N) is Null_Iir.  There are two
         --  exceptions:
         --  - N is also an instance (instance within an uninstantiated
         --    package).  As instances and origin share the same table,
         --    Get_Instance returns the origin.  During instantiation, the old
         --    value of Origin is saved so this case is correctly handled.
         --  - N is shared, so it was already instantiated.  This happends only
         --    for interface_constant of implicit operators.  In that case,
         --    multiple instances are created for the same node, which is not
         --    ideal.  That's still ok (if no infos are attached to the
         --    interface) and is the price to pay for this optimization.

         --  Create a new node.
         Res := Create_Iir (Kind);

         --  The origin of this new node is N.
         Set_Origin (Res, N);

         --  And the instance of N is RES.
         Set_Instance (N, Res);

         Set_Location (Res, Relocate (Get_Location (N)));

         for I in Fields'Range loop
            F := Fields (I);

            --  Fields that are handled specially.
            case F is
               when Field_Index_Subtype_List =>
                  --  Index_Subtype_List is always a reference, so retrieve
                  --  the instance of the referenced list.  This is a special
                  --  case because there is no origins for list.
                  declare
                     List : Iir_Flist;
                  begin
                     case Kind is
                        when Iir_Kind_Array_Type_Definition =>
                           List := Get_Index_Subtype_Definition_List (Res);
                        when Iir_Kind_Array_Subtype_Definition =>
                           List := Get_Index_Constraint_List (Res);
                           if List = Null_Iir_Flist then
                              List := Get_Index_Subtype_List
                                (Get_Denoted_Type_Mark (Res));
                           end if;
                        when others =>
                           --  All the nodes where Index_Subtype_List appears
                           --  are handled above.
                           raise Internal_Error;
                     end case;
                     Set_Index_Subtype_List (Res, List);
                  end;

               when Field_Simple_Aggregate_List =>
                  Set_Simple_Aggregate_List
                    (Res, Get_Simple_Aggregate_List (N));

               when Field_Subprogram_Body =>
                  --  This is a forward reference.  Not yet solved.
                  Set_Subprogram_Body (Res, Null_Iir);

               when Field_Subprogram_Specification =>
                  --  Resolve it.
                  Instantiate_Iir_Field (Res, N, F);

                  --  Set body.
                  pragma Assert (Kind_In (Res, Iir_Kind_Procedure_Body,
                                          Iir_Kind_Function_Body));
                  declare
                     Spec : constant Iir := Get_Subprogram_Specification (Res);
                  begin
                     pragma Assert (Get_Subprogram_Body (Spec) = Null_Iir);
                     Set_Subprogram_Body (Spec, Res);
                  end;

               when Field_Incomplete_Type_Ref_Chain =>
                  if Get_Kind (Res) = Iir_Kind_Access_Type_Definition then
                     --  Link
                     declare
                        Def : constant Iir := Get_Named_Entity
                          (Get_Designated_Subtype_Indication (Res));
                     begin
                        if Get_Kind (Def) = Iir_Kind_Incomplete_Type_Definition
                        then
                           Set_Incomplete_Type_Ref_Chain
                             (Res, Get_Incomplete_Type_Ref_Chain (Def));
                           Set_Incomplete_Type_Ref_Chain (Def, Res);
                        end if;
                     end;
                  end if;

               when Field_Designated_Type =>
                  null;
               when Field_Designated_Subtype_Indication =>
                  Instantiate_Iir_Field (Res, N, F);
                  --  The designated type will be patched later if it is an
                  --  incomplete type definition
                  Set_Designated_Type
                    (Res, Get_Type (Get_Designated_Subtype_Indication (Res)));

               when Field_Complete_Type_Definition =>
                  --  Will be set by the declaration of the complete type
                  null;
               when Field_Incomplete_Type_Declaration =>
                  Instantiate_Iir_Field (Res, N, F);
                  declare
                     Res_Decl : constant Iir :=
                       Get_Incomplete_Type_Declaration (Res);
                     N_Decl : constant Iir :=
                       Get_Incomplete_Type_Declaration (N);
                     Res_Complete : Iir;
                     N_Def, Res_Def : Iir;
                     N_El, Next_N_El : Iir;
                     Res_El, Next_Res_El : Iir;
                  begin
                     if Is_Valid (N_Decl) then
                        --  N/RES completes a type declaration.
                        N_Def := Get_Type_Definition (N_Decl);
                        Res_Def := Get_Type_Definition (Res_Decl);
                        --  Set Complete_Type_Definition
                        Res_Complete := Get_Type (Res);
                        Set_Complete_Type_Definition (Res_Def, Res_Complete);
                        --  Rebuild the list and patch designated types
                        N_El := N_Def;
                        Res_El := Res_Def;
                        loop
                           Next_N_El := Get_Incomplete_Type_Ref_Chain (N_El);
                           exit when Is_Null (Next_N_El);
                           Next_Res_El := Get_Instance (Next_N_El);
                           Set_Designated_Type (Next_Res_El, Res_Complete);
                           Set_Incomplete_Type_Ref_Chain (Res_El, Next_Res_El);
                           N_El := Next_N_El;
                        end loop;
                     end if;
                  end;

               when Field_Deferred_Declaration =>
                  if not Get_Deferred_Declaration_Flag (N)
                    and then Is_Valid (Get_Deferred_Declaration (N))
                  then
                     --  This is the completion.
                     declare
                        Incomplete_Decl_N : constant Iir :=
                          Get_Deferred_Declaration (N);
                        Incomplete_Decl_Res : constant Iir :=
                          Get_Instance (Incomplete_Decl_N);
                     begin
                        pragma Assert (Is_Valid (Incomplete_Decl_Res));
                        Set_Deferred_Declaration (Res, Incomplete_Decl_Res);
                        Set_Deferred_Declaration (Incomplete_Decl_Res, Res);
                     end;
                  end if;

               when Field_Protected_Type_Body =>
                  null;
               when Field_Protected_Type_Declaration =>
                  Instantiate_Iir_Field (Res, N, F);
                  Set_Protected_Type_Body
                    (Get_Protected_Type_Declaration (Res), Res);

               when Field_Package_Body =>
                  null;
               when Field_Package =>
                  Instantiate_Iir_Field (Res, N, F);
                  declare
                     Pkg : constant Iir := Get_Package (Res);
                  begin
                     --  The current node can be the body of a package; in that
                     --  case set the forward link.
                     --  Or it can be the body of an instantiated package; in
                     --  that case there is no forward link.
                     if Get_Kind (Pkg) = Iir_Kind_Package_Declaration then
                        Set_Package_Body (Get_Package (Res), Res);
                     end if;
                  end;

               when Field_Instance_Package_Body =>
                  --  Do not instantiate the body of a package while
                  --  instantiating a shared package.
                  if not Is_Within_Shared_Instance then
                     Instantiate_Iir_Field (Res, N, F);
                  end if;

               when Field_Subtype_Definition =>
                  --  TODO
                  null;

               when Field_Instance_Source_File =>
                  Set_Instance_Source_File
                    (Res, Files_Map.Create_Instance_Source_File
                       (Get_Instance_Source_File (N),
                        Get_Location (Res), Res));

               when Field_Generic_Chain
                 | Field_Declaration_Chain =>
                  if Kind = Iir_Kind_Package_Instantiation_Declaration then
                     declare
                        Prev_Instance_File : constant Source_File_Entry :=
                          Instance_File;
                     begin
                        --  Also relocate the instantiated declarations.
                        Instance_File := Get_Instance_Source_File (Res);
                        pragma Assert (Instance_File /= No_Source_File_Entry);
                        Instantiate_Iir_Field (Res, N, F);
                        Instance_File := Prev_Instance_File;
                     end;
                  else
                     Instantiate_Iir_Field (Res, N, F);
                  end if;

               when Field_Designated_Entity =>
                  --  This is a field of attribute_value.  It is a
                  --  forward_ref because it may reference a statement.
                  --  Handle it later.
                  null;

               when Field_Attribute_Value_Chain =>
                  --  Chain of attribute_value for a scope parent.  This is
                  --  a ref.  As the field is declared after the declarations
                  --  and statements of the scope, the attribute_value have
                  --  been instantiated.  So the reference can be resolved.
                  Instantiate_Iir_Field (Res, N, F);

                  --  However, the designated_entity of attribute_value have
                  --  not been resolved.  As they are now instantiated, the
                  --  forward_ref links can be fixed.
                  Instantiate_Attribute_Value_Chain (Res);

               when others =>
                  --  Common case.
                  Instantiate_Iir_Field (Res, N, F);
            end case;
         end loop;

         --  TODO: other forward references:
         --  incomplete constant
         --  incomplete type

         if Get_Kind (Res) in Iir_Kinds_Subprogram_Declaration then
            --  Recompute the hash as the interface may have
            --  changed due to instantiation.
            Sem_Utils.Compute_Subprogram_Hash (Res);
         end if;

         return Res;
      end;
   end Instantiate_Iir;

   --  As the scope generic interfaces extends beyond the immediate scope (see
   --  LRM08 12.2 Scope of declarations), they must be instantiated.
   function Instantiate_Generic_Chain (Inst : Iir; Inters : Iir) return Iir
   is
      Inter : Iir;
      First : Iir;
      Last : Iir;
      Res : Iir;
   begin
      First := Null_Iir;
      Last := Null_Iir;

      Inter := Inters;
      while Inter /= Null_Iir loop
         --  Create a copy of the interface.  FIXME: is it really needed ?
         Res := Create_Iir (Get_Kind (Inter));
         Set_Location (Res, Relocate (Get_Location (Inter)));