vhdl: renames iir_chains to vhdl.nodes_utils. Remove iir_chain_handling.

17 files changed, 134 insertions, 255 deletions

diff --git a/src/vhdl/iir_chain_handling.adb b/src/vhdl/iir_chain_handling.adb
deleted file mode 100644
index 1e70a366a..000000000
--- a/src/vhdl/iir_chain_handling.adb
+++ /dev/null
@@ -1,68 +0,0 @@
---  Generic package to handle chains.
---  Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold
---
---  GHDL is free software; you can redistribute it and/or modify it under
---  the terms of the GNU General Public License as published by the Free
---  Software Foundation; either version 2, or (at your option) any later
---  version.
---
---  GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
---  WARRANTY; without even the implied warranty of MERCHANTABILITY or
---  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
---  for more details.
---
---  You should have received a copy of the GNU General Public License
---  along with GHDL; see the file COPYING.  If not, write to the Free
---  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
---  02111-1307, USA.
-package body Iir_Chain_Handling is
-   procedure Build_Init (Last : out Iir) is
-   begin
-      Last := Null_Iir;
-   end Build_Init;
-
-   procedure Build_Init (Last : out Iir; Parent : Iir)
-   is
-      El : Iir;
-   begin
-      El := Get_Chain_Start (Parent);
-      if El /= Null_Iir then
-         loop
-            Last := El;
-            El := Get_Chain (El);
-            exit when El = Null_Iir;
-         end loop;
-      else
-         Last := Null_Iir;
-      end if;
-   end Build_Init;
-
-   procedure Append (Last : in out Iir; Parent : Iir; El : Iir) is
-   begin
-      if Last = Null_Iir then
-         Set_Chain_Start (Parent, El);
-      else
-         Set_Chain (Last, El);
-      end if;
-      Last := El;
-   end Append;
-
-   procedure Append_Subchain (Last : in out Iir; Parent : Iir; Els : Iir)
-   is
-      El : Iir;
-   begin
-      if Last = Null_Iir then
-         Set_Chain_Start (Parent, Els);
-      else
-         Set_Chain (Last, Els);
-      end if;
-      El := Els;
-      loop
-         Set_Parent (El, Parent);
-         Last := El;
-         El := Get_Chain (El);
-         exit when El = Null_Iir;
-      end loop;
-   end Append_Subchain;
-end Iir_Chain_Handling;
-
diff --git a/src/vhdl/iir_chain_handling.ads b/src/vhdl/iir_chain_handling.ads
deleted file mode 100644
index ea17ac98a..000000000
--- a/src/vhdl/iir_chain_handling.ads
+++ /dev/null
@@ -1,47 +0,0 @@
---  Generic package to handle chains.
---  Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold
---
---  GHDL is free software; you can redistribute it and/or modify it under
---  the terms of the GNU General Public License as published by the Free
---  Software Foundation; either version 2, or (at your option) any later
---  version.
---
---  GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
---  WARRANTY; without even the implied warranty of MERCHANTABILITY or
---  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
---  for more details.
---
---  You should have received a copy of the GNU General Public License
---  along with GHDL; see the file COPYING.  If not, write to the Free
---  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
---  02111-1307, USA.
-with Vhdl.Nodes; use Vhdl.Nodes;
-
---  The generic package Chain_Handling can be used to build or modify
---  chains.
---  The formals are the subprograms to get and set the first element
---   from the parent.
-generic
-   with function Get_Chain_Start (Parent : Iir) return Iir;
-   with procedure Set_Chain_Start (Parent : Iir; First : Iir);
-package Iir_Chain_Handling is
-
-   --  Building a chain:
-   --  Initialize (set LAST to NULL_IIR).
-   procedure Build_Init (Last : out Iir);
-   --  Set LAST with the last element of the chain.
-   --  This is an initialization for an already built chain.
-   procedure Build_Init (Last : out Iir; Parent : Iir);
-
-   --  Append element EL to the chain, whose parent is PARENT and last
-   --   element LAST.
-   procedure Append (Last : in out Iir; Parent : Iir; El : Iir);
-
-   --  Append a subchain whose first element is ELS to a chain, whose
-   --   parent is PARENT and last element LAST.
-   --   The Parent field of each elements of Els is set to PARENT.
-   --  Note: the Append procedure declared just above is an optimization
-   --   of this subprogram if ELS has no next element.  However, the
-   --   above subprogram does not set the Parent field of EL.
-   procedure Append_Subchain (Last : in out Iir; Parent : Iir; Els : Iir);
-end Iir_Chain_Handling;
diff --git a/src/vhdl/simulate/simul-elaboration.adb b/src/vhdl/simulate/simul-elaboration.adb
index da8c15664..862d5d34c 100644
--- a/src/vhdl/simulate/simul-elaboration.adb
+++ b/src/vhdl/simulate/simul-elaboration.adb
@@ -25,7 +25,7 @@ with Vhdl.Utils; use Vhdl.Utils;
 with Libraries;
 with Name_Table;
 with Simul.File_Operation;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Sem_Lib; use Vhdl.Sem_Lib;
 with Simul.Annotations; use Simul.Annotations;
 with Simul.Elaboration.AMS; use Simul.Elaboration.AMS;
diff --git a/src/vhdl/simulate/simul-execution.adb b/src/vhdl/simulate/simul-execution.adb
index b820e6425..19f9286b0 100644
--- a/src/vhdl/simulate/simul-execution.adb
+++ b/src/vhdl/simulate/simul-execution.adb
@@ -32,7 +32,7 @@ with Simul.Debugger; use Simul.Debugger;
 with Std_Names;
 with Str_Table;
 with Files_Map;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Simul.Simulation; use Simul.Simulation;
 with Grt.Astdio.Vhdl;
 with Grt.Stdio;
diff --git a/src/vhdl/translate/trans-chap7.adb b/src/vhdl/translate/trans-chap7.adb
index 85b74416e..347281d3a 100644
--- a/src/vhdl/translate/trans-chap7.adb
+++ b/src/vhdl/translate/trans-chap7.adb
@@ -20,7 +20,7 @@ with Ada.Text_IO;
 with Name_Table;
 with Str_Table;
 with Vhdl.Utils; use Vhdl.Utils;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Std_Package; use Vhdl.Std_Package;
 with Errorout; use Errorout;
 with Flags; use Flags;
diff --git a/src/vhdl/translate/trans-chap8.adb b/src/vhdl/translate/trans-chap8.adb
index 59bbca656..34adc93c6 100644
--- a/src/vhdl/translate/trans-chap8.adb
+++ b/src/vhdl/translate/trans-chap8.adb
@@ -19,7 +19,7 @@
 with Ada.Text_IO;
 with Std_Names;
 with Errorout; use Errorout;
-with Iir_Chains;
+with Vhdl.Nodes_Utils;
 with Vhdl.Canon;
 with Vhdl.Evaluation; use Vhdl.Evaluation;
 with Vhdl.Std_Package; use Vhdl.Std_Package;
@@ -2656,7 +2656,7 @@ package body Trans.Chap8 is
       type Mnode_Array is array (Natural range <>) of Mnode;
       type O_Enode_Array is array (Natural range <>) of O_Enode;
       Nbr_Assoc : constant Natural :=
-        Iir_Chains.Get_Chain_Length (Assoc_Chain);
+        Vhdl.Nodes_Utils.Get_Chain_Length (Assoc_Chain);
 
       --  References to the formals (for copy-out), and variables for whole
       --  actual of individual associations.
diff --git a/src/vhdl/vhdl-canon.adb b/src/vhdl/vhdl-canon.adb
index 379adaed6..99db770ae 100644
--- a/src/vhdl/vhdl-canon.adb
+++ b/src/vhdl/vhdl-canon.adb
@@ -23,7 +23,7 @@ with Name_Table;
 with Vhdl.Sem;
 with Vhdl.Sem_Inst;
 with Vhdl.Sem_Specs;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with PSL.Nodes;
 with PSL.Rewrites;
 with PSL.Build;
@@ -2888,13 +2888,13 @@ package body Vhdl.Canon is
    procedure Canon_Block_Configuration (Top : Iir_Design_Unit;
                                         Conf : Iir_Block_Configuration)
    is
-      use Iir_Chains.Configuration_Item_Chain_Handling;
+      --  use Iir_Chains.Configuration_Item_Chain_Handling;
       Spec : constant Iir := Get_Block_Specification (Conf);
       Blk : constant Iir := Get_Block_From_Block_Specification (Spec);
       Stmts : constant Iir := Get_Concurrent_Statement_Chain (Blk);
       El : Iir;
       Sub_Blk : Iir;
-      Last_Item : Iir;
+      First_Item, Last_Item : Iir;
 
       procedure Create_Default_Block_Configuration (Targ : Iir)
       is
@@ -2913,7 +2913,7 @@ package body Vhdl.Canon is
             Spec := El;
          end if;
          Set_Block_Specification (Res, Spec);
-         Append (Last_Item, Conf, Res);
+         Sub_Chain_Append (First_Item, Last_Item, Res);
       end Create_Default_Block_Configuration;
    begin
       --  Note: the only allowed declarations are use clauses, which are not
@@ -2923,8 +2923,6 @@ package body Vhdl.Canon is
 
       Clear_Instantiation_Configuration (Blk, False);
 
-      Build_Init (Last_Item, Conf);
-
       --  1) Configure instantiations with configuration specifications.
       --  TODO: merge.
       El := Get_Declaration_Chain (Blk);
@@ -2939,7 +2937,8 @@ package body Vhdl.Canon is
 
       --  2) Configure instantations with component configurations,
       --     and map block configurations with block/generate statements.
-      El := Get_Configuration_Item_Chain (Conf);
+      First_Item := Get_Configuration_Item_Chain (Conf);
+      El := First_Item;
       while El /= Null_Iir loop
          case Get_Kind (El) is
             when Iir_Kind_Configuration_Specification =>
@@ -2970,6 +2969,7 @@ package body Vhdl.Canon is
             when others =>
                Error_Kind ("canon_block_configuration(1)", El);
          end case;
+         Last_Item := El;
          El := Get_Chain (El);
       end loop;
 
@@ -3005,7 +3005,7 @@ package body Vhdl.Canon is
                           (Designator_List, Build_Simple_Name (El, El));
                         Set_Instantiation_List
                           (Res, List_To_Flist (Designator_List));
-                        Append (Last_Item, Conf, Res);
+                        Sub_Chain_Append (First_Item, Last_Item, Res);
                      end if;
                   elsif Get_Kind (Comp_Conf)
                     = Iir_Kind_Configuration_Specification
@@ -3038,7 +3038,7 @@ package body Vhdl.Canon is
                      Set_Binding_Indication
                        (Res, Get_Binding_Indication (Comp_Conf));
                      Set_Is_Ref (Res, True);
-                     Append (Last_Item, Conf, Res);
+                     Sub_Chain_Append (First_Item, Last_Item, Res);
                   end if;
                end;
             when Iir_Kind_Block_Statement =>
@@ -3106,7 +3106,7 @@ package body Vhdl.Canon is
                         Set_Base_Name (Blk_Spec, El);
                         Set_Prefix (Blk_Spec, Build_Simple_Name (Bod, Res));
                         Set_Block_Specification (Res, Blk_Spec);
-                        Append (Last_Item, Conf, Res);
+                        Sub_Chain_Append (First_Item, Last_Item, Res);
                      end if;
                   end if;
                end;
@@ -3123,9 +3123,10 @@ package body Vhdl.Canon is
          end case;
          El := Get_Chain (El);
       end loop;
+      Set_Configuration_Item_Chain (Conf, First_Item);
 
       --  4) Canon component configuration and block configuration (recursion).
-      El := Get_Configuration_Item_Chain (Conf);
+      El := First_Item;
       while El /= Null_Iir loop
          case Get_Kind (El) is
             when Iir_Kind_Block_Configuration =>
diff --git a/src/vhdl/iir_chains.adb b/src/vhdl/vhdl-nodes_utils.adb
index ca2593bd7..236956a8c 100644
--- a/src/vhdl/iir_chains.adb
+++ b/src/vhdl/vhdl-nodes_utils.adb
@@ -15,7 +15,8 @@
 --  along with GHDL; see the file COPYING.  If not, write to the Free
 --  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 --  02111-1307, USA.
-package body Iir_Chains is
+
+package body Vhdl.Nodes_Utils is
    function Get_Chain_Length (First : Iir) return Natural
    is
       Res : Natural := 0;
@@ -79,6 +80,26 @@ package body Iir_Chains is
       Last := Last_Sub;
    end Sub_Chain_Append_Chain;
 
+   procedure Sub_Chain_Append_Subchain (First, Last : in out Iir;
+                                        Sub : Iir)
+   is
+      N : Iir;
+   begin
+      pragma Assert (Sub /= Null_Iir);
+      if First = Null_Iir then
+         First := Sub;
+      else
+         Set_Chain (Last, Sub);
+      end if;
+
+      --  Update last.
+      N := Sub;
+      while N /= Null_Iir loop
+         Last := N;
+         N := Get_Chain (N);
+      end loop;
+   end Sub_Chain_Append_Subchain;
+
    function Is_Chain_Length_One (Chain : Iir) return Boolean is
    begin
       return Chain /= Null_Iir and then Get_Chain (Chain) = Null_Iir;
@@ -96,4 +117,4 @@ package body Iir_Chains is
       Set_Chain (Last, El);
       Last := El;
    end Insert_Incr;
-end Iir_Chains;
+end Vhdl.Nodes_Utils;
diff --git a/src/vhdl/iir_chains.ads b/src/vhdl/vhdl-nodes_utils.ads
index f443341ab..ef71e504b 100644
--- a/src/vhdl/iir_chains.ads
+++ b/src/vhdl/vhdl-nodes_utils.ads
@@ -16,11 +16,9 @@
 --  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 --  02111-1307, USA.
 with Vhdl.Nodes; use Vhdl.Nodes;
-with Iir_Chain_Handling;
-pragma Elaborate_All (Iir_Chain_Handling);
 with Vhdl.Nodes_Meta;
 
-package Iir_Chains is
+package Vhdl.Nodes_Utils is
    --  Chains are simply linked list of iirs.
    --  Elements of the chain are ordered.
    --  Each element of a chain have a Chain field, which points to the next
@@ -43,43 +41,6 @@ package Iir_Chains is
    --  have to be appended.  Indeed, there is no direct access to the last
    --  element of a chain.
    --  An efficient way to build a chain is to keep the last element of it.
-   --  See Iir_Chain_Handling package.
-
-   package Declaration_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Declaration_Chain,
-      Set_Chain_Start => Set_Declaration_Chain);
-
-   package Interface_Declaration_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Interface_Declaration_Chain,
-      Set_Chain_Start => Set_Interface_Declaration_Chain);
-
-   package Context_Items_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Context_Items,
-      Set_Chain_Start => Set_Context_Items);
-
-   package Unit_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Unit_Chain,
-      Set_Chain_Start => Set_Unit_Chain);
-
-   package Configuration_Item_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Configuration_Item_Chain,
-      Set_Chain_Start => Set_Configuration_Item_Chain);
-
-   package Entity_Class_Entry_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Entity_Class_Entry_Chain,
-      Set_Chain_Start => Set_Entity_Class_Entry_Chain);
-
-   package Selected_Waveform_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Selected_Waveform_Chain,
-      Set_Chain_Start => Set_Selected_Waveform_Chain);
-
-   package Association_Choices_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Association_Choices_Chain,
-      Set_Chain_Start => Set_Association_Choices_Chain);
-
-   package Case_Statement_Alternative_Chain_Handling is new Iir_Chain_Handling
-     (Get_Chain_Start => Get_Case_Statement_Alternative_Chain,
-      Set_Chain_Start => Set_Case_Statement_Alternative_Chain);
 
    --  Return the number of elements in a chain starting with FIRST.
    --  Not very efficient since O(N).
@@ -105,6 +66,8 @@ package Iir_Chains is
    --  Null_Iir.
    procedure Sub_Chain_Append_Chain (First, Last : in out Iir;
                                      First_Sub, Last_Sub : Iir);
+   procedure Sub_Chain_Append_Subchain (First, Last : in out Iir;
+                                        Sub : Iir);
 
    --  Return TRUE iff CHAIN is of length one, ie CHAIN is not NULL_IIR
    --  and chain (CHAIN) is NULL_IIR.
@@ -116,4 +79,4 @@ package Iir_Chains is
 
    --  Insert EL after LAST and set LAST to EL.
    procedure Insert_Incr (Last : in out Iir; El : Iir);
-end Iir_Chains;
+end Vhdl.Nodes_Utils;
diff --git a/src/vhdl/vhdl-parse.adb b/src/vhdl/vhdl-parse.adb
index dfd98c400..073fe65d3 100644
--- a/src/vhdl/vhdl-parse.adb
+++ b/src/vhdl/vhdl-parse.adb
@@ -15,7 +15,7 @@
 --  along with GHDL; see the file COPYING.  If not, write to the Free
 --  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 --  02111-1307, USA.
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Tokens; use Vhdl.Tokens;
 with Vhdl.Scanner; use Vhdl.Scanner;
 with Vhdl.Utils; use Vhdl.Utils;
@@ -2396,7 +2396,6 @@ package body Vhdl.Parse is
    function Parse_Physical_Type_Definition (Parent : Iir)
                                            return Iir_Physical_Type_Definition
    is
-      use Iir_Chains.Unit_Chain_Handling;
       Res: Iir_Physical_Type_Definition;
       Unit: Iir_Unit_Declaration;
       Last : Iir_Unit_Declaration;
@@ -2416,8 +2415,8 @@ package body Vhdl.Parse is
 
       Scan_Semi_Colon ("primary physical unit");
 
-      Build_Init (Last);
-      Append (Last, Res, Unit);
+      Set_Unit_Chain (Res, Unit);
+      Last := Unit;
 
       --  Parse secondary units.
       while Current_Token = Tok_Identifier loop
@@ -2457,7 +2456,9 @@ package body Vhdl.Parse is
                   Skip_Until_Semi_Colon;
             end case;
          end if;
-         Append (Last, Res, Unit);
+         Set_Chain (Last, Unit);
+         Last := Unit;
+
          Scan_Semi_Colon ("secondary physical unit");
       end loop;
 
@@ -4200,10 +4201,9 @@ package body Vhdl.Parse is
       case Current_Token is
          when Tok_Is =>
             declare
-               use Iir_Chains.Entity_Class_Entry_Chain_Handling;
                Res : Iir_Group_Template_Declaration;
                El : Iir_Entity_Class;
-               Last : Iir_Entity_Class;
+               First, Last : Iir_Entity_Class;
             begin
                Res := Create_Iir (Iir_Kind_Group_Template_Declaration);
                Set_Location (Res, Loc);
@@ -4215,14 +4215,14 @@ package body Vhdl.Parse is
                --  Skip '('.
                Expect_Scan (Tok_Left_Paren);
 
-               Build_Init (Last);
+               Sub_Chain_Init (First, Last);
                loop
-                  Append (Last, Res, Parse_Entity_Class_Entry);
+                  Sub_Chain_Append (First, Last, Parse_Entity_Class_Entry);
                   if Current_Token = Tok_Box then
                      El := Create_Iir (Iir_Kind_Entity_Class);
                      Set_Location (El);
                      Set_Entity_Class (El, Tok_Box);
-                     Append (Last, Res, El);
+                     Sub_Chain_Append (First, Last, El);
 
                      --  Skip '<>'.
                      Scan;
@@ -4238,6 +4238,7 @@ package body Vhdl.Parse is
                   --  Skip ','.
                   Scan;
                end loop;
+               Set_Entity_Class_Entry_Chain (Res, First);
 
                --  Skip ')' ';'
                Expect_Scan (Tok_Right_Paren);
@@ -4664,8 +4665,7 @@ package body Vhdl.Parse is
    --       architecture_body and generate_statement)
    procedure Parse_Declarative_Part (Parent : Iir)
    is
-      use Declaration_Chain_Handling;
-      Last_Decl : Iir;
+      First_Decl, Last_Decl : Iir;
       Decl : Iir;
       Package_Parent_Cache : Iir;
 
@@ -4678,7 +4678,7 @@ package body Vhdl.Parse is
       end Package_Parent;
    begin
       Package_Parent_Cache := Null_Iir;
-      Build_Init (Last_Decl);
+      Sub_Chain_Init (First_Decl, Last_Decl);
       loop
          Decl := Null_Iir;
          case Current_Token is
@@ -4966,10 +4966,18 @@ package body Vhdl.Parse is
             when others =>
                exit;
          end case;
-         if Decl /= Null_Iir then
-            Append_Subchain (Last_Decl, Parent, Decl);
-         end if;
+         while Decl /= Null_Iir loop
+            Set_Parent (Decl, Parent);
+            if First_Decl = Null_Iir then
+               First_Decl := Decl;
+            else
+               Set_Chain (Last_Decl, Decl);
+            end if;
+            Last_Decl := Decl;
+            Decl := Get_Chain (Decl);
+         end loop;
       end loop;
+      Set_Declaration_Chain (Parent, First_Decl);
    end Parse_Declarative_Part;
 
    --  precond : ENTITY
@@ -5153,10 +5161,9 @@ package body Vhdl.Parse is
    --  element_association ::= [ choices => ] expression
    function Parse_Aggregate return Iir
    is
-      use Iir_Chains.Association_Choices_Chain_Handling;
       Expr: Iir;
       Res: Iir;
-      Last : Iir;
+      First, Last : Iir;
       Assoc: Iir;
       Loc, Right_Loc : Location_Type;
    begin
@@ -5221,7 +5228,7 @@ package body Vhdl.Parse is
       end if;
       Res := Create_Iir (Iir_Kind_Aggregate);
       Set_Location (Res, Loc);
-      Build_Init (Last);
+      Sub_Chain_Init (First, Last);
       loop
          if Current_Token = Tok_Others then
             Assoc := Parse_A_Choice (Null_Iir, Loc);
@@ -5256,7 +5263,7 @@ package body Vhdl.Parse is
             end case;
          end if;
          Set_Associated_Expr (Assoc, Expr);
-         Append_Subchain (Last, Res, Assoc);
+         Sub_Chain_Append_Subchain (First, Last, Assoc);
          exit when Current_Token /= Tok_Comma;
 
          Loc := Get_Token_Location;
@@ -5266,6 +5273,7 @@ package body Vhdl.Parse is
 
          Expr := Null_Iir;
       end loop;
+      Set_Association_Choices_Chain (Res, First);
 
       --  Eat ')'.
       Expect_Scan (Tok_Right_Paren);
@@ -6181,12 +6189,11 @@ package body Vhdl.Parse is
    --      waveform WHEN choices
    function Parse_Selected_Signal_Assignment return Iir
    is
-      use Iir_Chains.Selected_Waveform_Chain_Handling;
       Res : Iir;
       Assoc : Iir;
       Wf_Chain : Iir_Waveform_Element;
       Target : Iir;
-      Last : Iir;
+      First, Last : Iir;
       When_Loc : Location_Type;
    begin
       --  Skip 'with'.
@@ -6208,7 +6215,7 @@ package body Vhdl.Parse is
 
       Parse_Options (Res);
 
-      Build_Init (Last);
+      Sub_Chain_Init (First, Last);
       loop
          Wf_Chain := Parse_Waveform;
          Expect (Tok_When, "'when' expected after waveform");
@@ -6219,11 +6226,12 @@ package body Vhdl.Parse is
 
          Parse_Choices (Null_Iir, When_Loc, Assoc);
          Set_Associated_Chain (Assoc, Wf_Chain);
-         Append_Subchain (Last, Res, Assoc);
+         Sub_Chain_Append_Subchain (First, Last, Assoc);
          exit when Current_Token /= Tok_Comma;
          --  Skip ','.
          Scan;
       end loop;
+      Set_Selected_Waveform_Chain (Res, First);
 
       Expect_Scan (Tok_Semi_Colon, "';' expected at end of signal assignment");
 
@@ -6768,10 +6776,9 @@ package body Vhdl.Parse is
    --  case_statement_alternative ::= WHEN choices => sequence_of_statements
    function Parse_Case_Statement (Label : Name_Id) return Iir
    is
-      use Iir_Chains.Case_Statement_Alternative_Chain_Handling;
       Stmt : Iir;
       Assoc: Iir;
-      Last_Assoc : Iir;
+      First_Assoc, Last_Assoc : Iir;
       When_Loc : Location_Type;
    begin
       Stmt := Create_Iir (Iir_Kind_Case_Statement);
@@ -6791,7 +6798,7 @@ package body Vhdl.Parse is
          Error_Msg_Parse ("missing alternative in case statement");
       end if;
 
-      Build_Init (Last_Assoc);
+      Sub_Chain_Init (First_Assoc, Last_Assoc);
       while Current_Token = Tok_When loop
          When_Loc := Get_Token_Location;
 
@@ -6804,8 +6811,9 @@ package body Vhdl.Parse is
          Expect_Scan (Tok_Double_Arrow);
 
          Set_Associated_Chain (Assoc, Parse_Sequential_Statements (Stmt));
-         Append_Subchain (Last_Assoc, Stmt, Assoc);
+         Sub_Chain_Append_Subchain (First_Assoc, Last_Assoc, Assoc);
       end loop;
+      Set_Case_Statement_Alternative_Chain (Stmt, First_Assoc);
 
       if Flag_Elocations then
          Create_Elocations (Stmt);
@@ -9145,26 +9153,26 @@ package body Vhdl.Parse is
       --  Parse use clauses.
       if Current_Token = Tok_Use then
          declare
-            Last : Iir;
-            use Declaration_Chain_Handling;
+            First, Last : Iir;
          begin
-            Build_Init (Last);
+            Sub_Chain_Init (First, Last);
 
             while Current_Token = Tok_Use loop
-               Append_Subchain (Last, Res, Parse_Use_Clause);
+               Sub_Chain_Append_Subchain (First, Last, Parse_Use_Clause);
             end loop;
+            Set_Declaration_Chain (Res, First);
          end;
       end if;
 
       --  Parse configuration item list
       declare
-         use Iir_Chains.Configuration_Item_Chain_Handling;
-         Last : Iir;
+         First, Last : Iir;
       begin
-         Build_Init (Last);
+         Sub_Chain_Init (First, Last);
          while Current_Token = Tok_For loop
-            Append (Last, Res, Parse_Configuration_Item);
+            Sub_Chain_Append (First, Last, Parse_Configuration_Item);
          end loop;
+         Set_Configuration_Item_Chain (Res, First);
       end;
       Expect_Scan (Tok_End);
       Expect_Scan (Tok_For);
@@ -9279,17 +9287,16 @@ package body Vhdl.Parse is
    --  FIXME: attribute_specification, group_declaration
    procedure Parse_Configuration_Declarative_Part (Parent : Iir)
    is
-      use Declaration_Chain_Handling;
-      Last : Iir;
+      First, Last : Iir;
       El : Iir;
    begin
-      Build_Init (Last);
+      Sub_Chain_Init (First, Last);
       loop
          case Current_Token is
             when Tok_Invalid =>
                raise Internal_Error;
             when Tok_Use =>
-               Append_Subchain (Last, Parent, Parse_Use_Clause);
+               Sub_Chain_Append_Subchain (First, Last, Parse_Use_Clause);
             when Tok_Attribute =>
                El := Parse_Attribute;
                if El /= Null_Iir then
@@ -9297,7 +9304,7 @@ package body Vhdl.Parse is
                      Error_Msg_Parse
                        ("attribute declaration not allowed here");
                   end if;
-                  Append (Last, Parent, El);
+                  Sub_Chain_Append (First, Last, El);
                end if;
             when Tok_Group =>
                El := Parse_Group;
@@ -9306,12 +9313,13 @@ package body Vhdl.Parse is
                      Error_Msg_Parse
                        ("group template declaration not allowed here");
                   end if;
-                  Append (Last, Parent, El);
+                  Sub_Chain_Append (First, Last, El);
                end if;
             when others =>
                exit;
          end case;
       end loop;
+      Set_Declaration_Chain (Parent, First);
    end Parse_Configuration_Declarative_Part;
 
    --  precond : CONFIGURATION
@@ -9622,11 +9630,10 @@ package body Vhdl.Parse is
    --  context_item ::= library_clause | use_clause | context_reference
    procedure Parse_Context_Clause (Unit : Iir)
    is
-      use Context_Items_Chain_Handling;
-      Last : Iir;
+      First, Last : Iir;
       Els : Iir;
    begin
-      Build_Init (Last);
+      Sub_Chain_Init (First, Last);
 
       loop
          case Current_Token is
@@ -9659,8 +9666,9 @@ package body Vhdl.Parse is
             when others =>
                exit;
          end case;
-         Append_Subchain (Last, Unit, Els);
+         Sub_Chain_Append_Subchain (First, Last, Els);
       end loop;
+      Set_Context_Items (Unit, First);
    end Parse_Context_Clause;
 
    --  Precond:  IS
diff --git a/src/vhdl/vhdl-sem.adb b/src/vhdl/vhdl-sem.adb
index 077d9c5f6..62ab6b653 100644
--- a/src/vhdl/vhdl-sem.adb
+++ b/src/vhdl/vhdl-sem.adb
@@ -33,7 +33,7 @@ with Flags; use Flags;
 with Str_Table;
 with Vhdl.Sem_Utils;
 with Vhdl.Sem_Stmts; use Vhdl.Sem_Stmts;
-with Iir_Chains;
+with Vhdl.Nodes_Utils;
 with Vhdl.Xrefs; use Vhdl.Xrefs;
 
 package body Vhdl.Sem is
@@ -1710,7 +1710,7 @@ package body Vhdl.Sem is
       Nbr_Interfaces : Natural;
       Is_Method : Boolean;
    begin
-      Nbr_Interfaces := Iir_Chains.Get_Chain_Length
+      Nbr_Interfaces := Vhdl.Nodes_Utils.Get_Chain_Length
         (Get_Interface_Declaration_Chain (Subprg));
 
       --  For vhdl-02, the protected variable is an implicit parameter.
diff --git a/src/vhdl/vhdl-sem_assocs.adb b/src/vhdl/vhdl-sem_assocs.adb
index 6a9226fe0..41b97953e 100644
--- a/src/vhdl/vhdl-sem_assocs.adb
+++ b/src/vhdl/vhdl-sem_assocs.adb
@@ -27,7 +27,7 @@ with Vhdl.Sem_Types;
 with Vhdl.Sem_Decls;
 with Vhdl.Std_Package;
 with Vhdl.Sem_Scopes;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Xrefs;
 
 package body Vhdl.Sem_Assocs is
diff --git a/src/vhdl/vhdl-sem_expr.adb b/src/vhdl/vhdl-sem_expr.adb
index 096cd8961..151d2d54c 100644
--- a/src/vhdl/vhdl-sem_expr.adb
+++ b/src/vhdl/vhdl-sem_expr.adb
@@ -27,7 +27,7 @@ with Name_Table;
 with Str_Table;
 with Vhdl.Utils; use Vhdl.Utils;
 with Vhdl.Evaluation; use Vhdl.Evaluation;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Sem_Types;
 with Vhdl.Sem_Stmts; use Vhdl.Sem_Stmts;
 with Vhdl.Sem_Assocs; use Vhdl.Sem_Assocs;
@@ -1829,7 +1829,7 @@ package body Vhdl.Sem_Expr is
             --
             --  GHDL: So even in presence of default expression in a parameter,
             --  a unary operation has to match with a binary operator.
-            if Iir_Chains.Get_Chain_Length (Interface_Chain) /= Arity then
+            if Get_Chain_Length (Interface_Chain) /= Arity then
                goto Continue;
             end if;
 
diff --git a/src/vhdl/vhdl-sem_names.adb b/src/vhdl/vhdl-sem_names.adb
index 8cf89d02a..07773341b 100644
--- a/src/vhdl/vhdl-sem_names.adb
+++ b/src/vhdl/vhdl-sem_names.adb
@@ -22,7 +22,7 @@ with Flags; use Flags;
 with Name_Table;
 with Vhdl.Std_Package; use Vhdl.Std_Package;
 with Types; use Types;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Std_Names;
 with Vhdl.Sem;
 with Vhdl.Sem_Lib; use Vhdl.Sem_Lib;
diff --git a/src/vhdl/vhdl-sem_specs.adb b/src/vhdl/vhdl-sem_specs.adb
index 6bf56aed5..5b63995bc 100644
--- a/src/vhdl/vhdl-sem_specs.adb
+++ b/src/vhdl/vhdl-sem_specs.adb
@@ -26,7 +26,7 @@ with Vhdl.Sem_Lib; use Vhdl.Sem_Lib;
 with Vhdl.Sem_Scopes; use Vhdl.Sem_Scopes;
 with Vhdl.Sem_Assocs; use Vhdl.Sem_Assocs;
 with Libraries;
-with Iir_Chains; use Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Flags; use Flags;
 with Std_Names;
 with Vhdl.Sem_Decls;
@@ -1735,7 +1735,7 @@ package body Vhdl.Sem_Specs is
          Sub_Chain_Append (Res, Last, Assoc);
          Ent_El := Get_Chain (Ent_El);
       end loop;
-      if Iir_Chains.Get_Chain_Length (Comp_Chain) /= Found then
+      if Nodes_Utils.Get_Chain_Length (Comp_Chain) /= Found then
          --  At least one component generic/port cannot be associated with
          --  the entity one.
 
diff --git a/src/vhdl/vhdl-sem_utils.adb b/src/vhdl/vhdl-sem_utils.adb
index 0f3045bdf..65ffda3c0 100644
--- a/src/vhdl/vhdl-sem_utils.adb
+++ b/src/vhdl/vhdl-sem_utils.adb
@@ -19,8 +19,8 @@ with Ada.Unchecked_Conversion;
 with Types; use Types;
 with Flags; use Flags;
 with Errorout; use Errorout;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 with Vhdl.Utils; use Vhdl.Utils;
-with Iir_Chains; use Iir_Chains;
 with Vhdl.Ieee.Std_Logic_1164;
 with Std_Names;
 with Vhdl.Std_Package; use Vhdl.Std_Package;
@@ -128,7 +128,6 @@ package body Vhdl.Sem_Utils is
    procedure Create_Implicit_File_Primitives
      (Decl : Iir_Type_Declaration; Type_Definition : Iir_File_Type_Definition)
    is
-      use Iir_Chains.Interface_Declaration_Chain_Handling;
       Type_Mark : constant Iir := Get_File_Type_Mark (Type_Definition);
       Type_Mark_Type : constant Iir := Get_Type (Type_Mark);
       Proc: Iir_Procedure_Declaration;
@@ -136,7 +135,7 @@ package body Vhdl.Sem_Utils is
       Inter: Iir;
       Loc : Location_Type;
       File_Interface_Kind : Iir_Kind;
-      Last_Interface : Iir;
+      First_Interface, Last_Interface : Iir;
       Last : Iir;
    begin
       Last := Decl;
@@ -152,7 +151,7 @@ package body Vhdl.Sem_Utils is
             Set_Identifier (Proc, Std_Names.Name_File_Open);
             Set_Visible_Flag (Proc, True);
             Set_Wait_State (Proc, False);
-            Build_Init (Last_Interface);
+            Sub_Chain_Init (First_Interface, Last_Interface);
             case I is
                when 1 =>
                   Set_Implicit_Definition (Proc, Iir_Predefined_File_Open);
@@ -168,7 +167,7 @@ package body Vhdl.Sem_Utils is
                             Std_Package.File_Open_Status_Type_Definition);
                   Set_Mode (Inter, Iir_Out_Mode);
                   Set_Visible_Flag (Inter, True);
-                  Append (Last_Interface, Proc, Inter);
+                  Sub_Chain_Append (First_Interface, Last_Interface, Inter);
             end case;
             --  File F : FT
             Inter := Create_Iir (Iir_Kind_Interface_File_Declaration);
@@ -177,7 +176,7 @@ package body Vhdl.Sem_Utils is
             Set_Type (Inter, Type_Definition);
             Set_Mode (Inter, Iir_Inout_Mode);
             Set_Visible_Flag (Inter, True);
-            Append (Last_Interface, Proc, Inter);
+            Sub_Chain_Append (First_Interface, Last_Interface, Inter);
             --  External_Name : in STRING
             Inter := Create_Iir (Iir_Kind_Interface_Constant_Declaration);
             Set_Location (Inter, Loc);
@@ -185,7 +184,7 @@ package body Vhdl.Sem_Utils is
             Set_Type (Inter, Std_Package.String_Type_Definition);
             Set_Mode (Inter, Iir_In_Mode);
             Set_Visible_Flag (Inter, True);
-            Append (Last_Interface, Proc, Inter);
+            Sub_Chain_Append (First_Interface, Last_Interface, Inter);
             --  Open_Kind : in File_Open_Kind := Read_Mode.
             Inter := Create_Iir (Iir_Kind_Interface_Constant_Declaration);
             Set_Location (Inter, Loc);
@@ -196,7 +195,8 @@ package body Vhdl.Sem_Utils is
               (Inter,
                Build_Simple_Name (Std_Package.File_Open_Kind_Read_Mode, Loc));
             Set_Visible_Flag (Inter, True);
-            Append (Last_Interface, Proc, Inter);
+            Sub_Chain_Append (First_Interface, Last_Interface, Inter);
+            Set_Interface_Declaration_Chain (Proc, First_Interface);
             Compute_Subprogram_Hash (Proc);
             -- Add it to the list.
             Insert_Incr (Last, Proc);
@@ -210,14 +210,13 @@ package body Vhdl.Sem_Utils is
          Set_Implicit_Definition (Proc, Iir_Predefined_File_Close);
          Set_Visible_Flag (Proc, True);
          Set_Wait_State (Proc, False);
-         Build_Init (Last_Interface);
          Inter := Create_Iir (Iir_Kind_Interface_File_Declaration);
          Set_Identifier (Inter, Std_Names.Name_F);
          Set_Location (Inter, Loc);
          Set_Type (Inter, Type_Definition);
          Set_Mode (Inter, Iir_Inout_Mode);
          Set_Visible_Flag (Inter, True);
-         Append (Last_Interface, Proc, Inter);
+         Set_Interface_Declaration_Chain (Proc, Inter);
          Compute_Subprogram_Hash (Proc);
          -- Add it to the list.
          Insert_Incr (Last, Proc);
@@ -236,14 +235,14 @@ package body Vhdl.Sem_Utils is
       Set_Parent (Proc, Get_Parent (Decl));
       Set_Visible_Flag (Proc, True);
       Set_Wait_State (Proc, False);
-      Build_Init (Last_Interface);
+      Sub_Chain_Init (First_Interface, Last_Interface);
       Inter := Create_Iir (File_Interface_Kind);
       Set_Identifier (Inter, Std_Names.Name_F);
       Set_Location (Inter, Loc);
       Set_Type (Inter, Type_Definition);
       Set_Mode (Inter, Iir_In_Mode);
       Set_Visible_Flag (Inter, True);
-      Append (Last_Interface, Proc, Inter);
+      Sub_Chain_Append (First_Interface, Last_Interface, Inter);
       Inter := Create_Iir (Iir_Kind_Interface_Variable_Declaration);
       Set_Identifier (Inter, Std_Names.Name_Value);
       Set_Location (Inter, Loc);
@@ -251,7 +250,7 @@ package body Vhdl.Sem_Utils is
       Set_Type (Inter, Type_Mark_Type);
       Set_Mode (Inter, Iir_Out_Mode);
       Set_Visible_Flag (Inter, True);
-      Append (Last_Interface, Proc, Inter);
+      Sub_Chain_Append (First_Interface, Last_Interface, Inter);
       if Get_Kind (Type_Mark_Type) in Iir_Kinds_Array_Type_Definition
         and then Get_Constraint_State (Type_Mark_Type) /= Fully_Constrained
       then
@@ -261,11 +260,12 @@ package body Vhdl.Sem_Utils is
          Set_Type (Inter, Std_Package.Natural_Subtype_Definition);
          Set_Mode (Inter, Iir_Out_Mode);
          Set_Visible_Flag (Inter, True);
-         Append (Last_Interface, Proc, Inter);
+         Sub_Chain_Append (First_Interface, Last_Interface, Inter);
          Set_Implicit_Definition (Proc, Iir_Predefined_Read_Length);
       else
          Set_Implicit_Definition (Proc, Iir_Predefined_Read);
       end if;
+      Set_Interface_Declaration_Chain (Proc, First_Interface);
       Compute_Subprogram_Hash (Proc);
       -- Add it to the list.
       Insert_Incr (Last, Proc);
@@ -277,7 +277,7 @@ package body Vhdl.Sem_Utils is
       Set_Parent (Proc, Get_Parent (Decl));
       Set_Visible_Flag (Proc, True);
       Set_Wait_State (Proc, False);
-      Build_Init (Last_Interface);
+      Sub_Chain_Init (First_Interface, Last_Interface);
       Inter := Create_Iir (File_Interface_Kind);
       Set_Identifier (Inter, Std_Names.Name_F);
       Set_Location (Inter, Loc);
@@ -286,7 +286,7 @@ package body Vhdl.Sem_Utils is
       Set_Name_Staticness (Inter, Locally);
       Set_Expr_Staticness (Inter, None);
       Set_Visible_Flag (Inter, True);
-      Append (Last_Interface, Proc, Inter);
+      Sub_Chain_Append (First_Interface, Last_Interface, Inter);
       Inter := Create_Iir (Iir_Kind_Interface_Constant_Declaration);
       Set_Identifier (Inter, Std_Names.Name_Value);
       Set_Location (Inter, Loc);
@@ -294,8 +294,9 @@ package body Vhdl.Sem_Utils is
       Set_Type (Inter, Type_Mark_Type);
       Set_Mode (Inter, Iir_In_Mode);
       Set_Visible_Flag (Inter, True);
-      Append (Last_Interface, Proc, Inter);
+      Sub_Chain_Append (First_Interface, Last_Interface, Inter);
       Set_Implicit_Definition (Proc, Iir_Predefined_Write);
+      Set_Interface_Declaration_Chain (Proc, First_Interface);
       Compute_Subprogram_Hash (Proc);
       -- Add it to the list.
       Insert_Incr (Last, Proc);
@@ -308,7 +309,6 @@ package body Vhdl.Sem_Utils is
          Set_Parent (Proc, Get_Parent (Decl));
          Set_Visible_Flag (Proc, True);
          Set_Wait_State (Proc, False);
-         Build_Init (Last_Interface);
          Inter := Create_Iir (File_Interface_Kind);
          Set_Identifier (Inter, Std_Names.Name_F);
          Set_Location (Inter, Loc);
@@ -316,31 +316,32 @@ package body Vhdl.Sem_Utils is
          Set_Name_Staticness (Inter, Locally);
          Set_Expr_Staticness (Inter, None);
          Set_Visible_Flag (Inter, True);
-         Append (Last_Interface, Proc, Inter);
          Set_Implicit_Definition (Proc, Iir_Predefined_Flush);
+         Set_Interface_Declaration_Chain (Proc, Inter);
          Compute_Subprogram_Hash (Proc);
          -- Add it to the list.
          Insert_Incr (Last, Proc);
       end if;
+
       -- Create the implicit function endfile declaration.
       Func := Create_Iir (Iir_Kind_Function_Declaration);
       Set_Identifier (Func, Std_Names.Name_Endfile);
       Set_Location (Func, Loc);
       Set_Parent (Func, Get_Parent (Decl));
       Set_Visible_Flag (Func, True);
-      Build_Init (Last_Interface);
       Inter := Create_Iir (File_Interface_Kind);
       Set_Identifier (Inter, Std_Names.Name_F);
       Set_Location (Inter, Loc);
       Set_Type (Inter, Type_Definition);
       Set_Mode (Inter, Iir_In_Mode);
       Set_Visible_Flag (Inter, True);
-      Append (Last_Interface, Func, Inter);
       Set_Return_Type (Func, Std_Package.Boolean_Type_Definition);
       Set_Implicit_Definition (Func, Iir_Predefined_Endfile);
+      Set_Interface_Declaration_Chain (Func, Inter);
       Compute_Subprogram_Hash (Func);
       -- Add it to the list.
       Insert_Incr (Last, Func);
+
    end Create_Implicit_File_Primitives;
 
    procedure Create_Implicit_Operations
diff --git a/src/vhdl/vhdl-std_package.adb b/src/vhdl/vhdl-std_package.adb
index fb68dfd64..3d7a78c85 100644
--- a/src/vhdl/vhdl-std_package.adb
+++ b/src/vhdl/vhdl-std_package.adb
@@ -23,7 +23,7 @@ with Std_Names; use Std_Names;
 with Flags; use Flags;
 with Vhdl.Utils;
 with Vhdl.Sem_Utils;
-with Iir_Chains;
+with Vhdl.Nodes_Utils; use Vhdl.Nodes_Utils;
 
 package body Vhdl.Std_Package is
    type Bound_Array is array (Boolean) of Iir_Int64;
@@ -790,8 +790,7 @@ package body Vhdl.Std_Package is
       -- time definition
       declare
          Time_Staticness : Iir_Staticness;
-         Last_Unit : Iir_Unit_Declaration;
-         use Iir_Chains.Unit_Chain_Handling;
+         First_Unit, Last_Unit : Iir_Unit_Declaration;
 
          function Create_Std_Phys_Lit_Wo_Unit (Value : Iir_Int64; Unit : Iir)
                                       return Iir_Physical_Int_Literal
@@ -841,7 +840,7 @@ package body Vhdl.Std_Package is
 
             Set_Expr_Staticness (Unit, Time_Staticness);
             Set_Name_Staticness (Unit, Locally);
-            Append (Last_Unit, Time_Type_Definition, Unit);
+            Sub_Chain_Append (First_Unit, Last_Unit, Unit);
          end Create_Unit;
 
          Constraint : Iir_Range_Expression;
@@ -861,7 +860,7 @@ package body Vhdl.Std_Package is
                               not Flags.Flag_Whole_Analyze);
          Set_End_Has_Reserved_Id (Time_Type_Definition, True);
 
-         Build_Init (Last_Unit);
+         Sub_Chain_Init (First_Unit, Last_Unit);
 
          Time_Fs_Unit := Create_Std_Decl (Iir_Kind_Unit_Declaration);
          Set_Std_Identifier (Time_Fs_Unit, Name_Fs);
@@ -870,7 +869,7 @@ package body Vhdl.Std_Package is
          Set_Name_Staticness (Time_Fs_Unit, Locally);
          Set_Physical_Literal
            (Time_Fs_Unit, Create_Std_Phys_Lit (1, Time_Fs_Unit));
-         Append (Last_Unit, Time_Type_Definition, Time_Fs_Unit);
+         Sub_Chain_Append (First_Unit, Last_Unit, Time_Fs_Unit);
 
          Create_Unit (Time_Ps_Unit, 1000, Time_Fs_Unit, Name_Ps);
          Create_Unit (Time_Ns_Unit, 1000, Time_Ps_Unit, Name_Ns);
@@ -886,6 +885,7 @@ package body Vhdl.Std_Package is
          Set_Identifier (Time_Type_Declaration, Name_Time);
          Set_Type_Definition (Time_Type_Declaration, Time_Type_Definition);
          Set_Type_Declarator (Time_Type_Definition, Time_Type_Declaration);
+         Set_Unit_Chain (Time_Type_Definition, First_Unit);
          Add_Decl (Time_Type_Declaration);
 
          Add_Implicit_Operations (Time_Type_Declaration);