Add support for --time-resolution (jit only). Fix #613

21 files changed, 456 insertions, 478 deletions

diff --git a/src/flags.adb b/src/flags.adb
index 4bd150124..de536815b 100644
--- a/src/flags.adb
+++ b/src/flags.adb
@@ -41,16 +41,7 @@ package body Flags is
          Flag_String (4) := 't';
       end if;
 
-      if Flag_Time_64 then
-         --  Time_Resolution is always fs.
-         Flag_String (5) := '-';
-      elsif Vhdl_Std = Vhdl_87 then
-         --  Time_Resolution is fixed in vhdl87, as time expressions are
-         --  locally static.
-         Flag_String (5) := Time_Resolution;
-      else
-         --  Time_Resolution can be changed at simulation time.
-         Flag_String (5) := '?';
-      end if;
+      --  Time_Resolution is always fs.
+      Flag_String (5) := '-';
    end Create_Flag_String;
 end Flags;
diff --git a/src/flags.ads b/src/flags.ads
index f9c0be2a1..3134c14de 100644
--- a/src/flags.ads
+++ b/src/flags.ads
@@ -122,18 +122,6 @@ package Flags is
    --  If set, performs VITAL checks.
    Flag_Vital_Checks : Boolean := True;
 
-   -- --time-resolution=X
-   -- Where X corresponds to:
-   -- fs => 'f'
-   -- ps => 'p'
-   -- ns => 'n'
-   -- us => 'u'
-   -- ms => 'm'
-   -- sec => 's'
-   -- min => 'M'
-   -- hr => 'h'
-   Time_Resolution: Character := 'f';
-
    --  Integer and time types can be either 32 bits or 64 bits values.
    --  The default is 32 bits for Integer and 64 bits for Time.
    --  Be very careful: if you don't use the default sizes, you may have to
diff --git a/src/ghdldrv/ghdlcomp.adb b/src/ghdldrv/ghdlcomp.adb
index e9a0338a9..df7f02cb1 100644
--- a/src/ghdldrv/ghdlcomp.adb
+++ b/src/ghdldrv/ghdlcomp.adb
@@ -49,6 +49,7 @@ package body Ghdlcomp is
                             Arg : String;
                             Res : out Option_Res)
    is
+      pragma Assert (Option'First = 1);
    begin
       if Option = "--expect-failure" then
          Flag_Expect_Failure := True;
@@ -58,6 +59,31 @@ package body Ghdlcomp is
          Res := Option_Ok;
       elsif Hooks.Decode_Option.all (Option) then
          Res := Option_Ok;
+      elsif Option'Length > 18
+        and then Option (1 .. 18) = "--time-resolution="
+      then
+         Res := Option_Ok;
+         if Option (19 .. Option'Last) = "fs" then
+            Time_Resolution := 'f';
+         elsif Option (19 .. Option'Last) = "ps" then
+            Time_Resolution := 'p';
+         elsif Option (19 .. Option'Last) = "ns" then
+            Time_Resolution := 'n';
+         elsif Option (19 .. Option'Last) = "us" then
+            Time_Resolution := 'u';
+         elsif Option (19 .. Option'Last) = "ms" then
+            Time_Resolution := 'm';
+         elsif Option (19 .. Option'Last) = "sec" then
+            Time_Resolution := 's';
+         elsif Option (19 .. Option'Last) = "min" then
+            Time_Resolution := 'M';
+         elsif Option (19 .. Option'Last) = "hr" then
+            Time_Resolution := 'h';
+         elsif Option (19 .. Option'Last) = "auto" then
+            Time_Resolution := 'a';
+         else
+            Res := Option_Bad;
+         end if;
       else
          Decode_Option (Command_Lib (Cmd), Option, Arg, Res);
       end if;
@@ -71,6 +97,8 @@ package body Ghdlcomp is
       Disp_Long_Help (Command_Lib (Cmd));
       Hooks.Disp_Long_Help.all;
       Put_Line (" --expect-failure  Expect analysis/elaboration failure");
+      Put_Line (" --time-resolution=UNIT   Set the resolution of type time");
+      Put_Line ("            UNIT can be fs, ps, ns, us, ms, sec, min or hr");
    end Disp_Long_Help;
 
    --  Command -r
@@ -366,8 +394,6 @@ package body Ghdlcomp is
          raise Compilation_Error;
       end if;
 
-      Setup_Libraries (True);
-
       Hooks.Compile_Init.all (True);
 
       --  Parse all files.
diff --git a/src/ghdldrv/ghdlcomp.ads b/src/ghdldrv/ghdlcomp.ads
index 487f70fc1..0e265a7c2 100644
--- a/src/ghdldrv/ghdlcomp.ads
+++ b/src/ghdldrv/ghdlcomp.ads
@@ -69,6 +69,18 @@ package Ghdlcomp is
    --  Output of --disp-config.
    procedure Disp_Config;
 
+   -- --time-resolution=X
+   -- Where X corresponds to:
+   -- fs => 'f'
+   -- ps => 'p'
+   -- ns => 'n'
+   -- us => 'u'
+   -- ms => 'm'
+   -- sec => 's'
+   -- min => 'M'
+   -- hr => 'h'
+   Time_Resolution: Character := 'f';
+
    --  Functionnal interface.
    --  Must be first initialized by Compile_Init
    procedure Compile_Analyze_Init (Load_Work : Boolean := True);
diff --git a/src/ghdldrv/ghdldrv.adb b/src/ghdldrv/ghdldrv.adb
index b68c46850..31d4a530b 100644
--- a/src/ghdldrv/ghdldrv.adb
+++ b/src/ghdldrv/ghdldrv.adb
@@ -677,6 +677,11 @@ package body Ghdldrv is
             Add_Argument (Compiler_Args, new String'(Opt));
          end if;
          Res := Option_Ok;
+      elsif Opt'Length > 18
+        and then Opt (1 .. 18) = "--time-resolution="
+      then
+         Error ("option --time-resolution not supported by back-end");
+         raise Option_Error;
       elsif Opt'Length >= 2
         and then (Opt (2) = 'O' or Opt (2) = 'f')
       then
diff --git a/src/ghdldrv/ghdlrun.adb b/src/ghdldrv/ghdlrun.adb
index 76c683ab2..b2cff0411 100644
--- a/src/ghdldrv/ghdlrun.adb
+++ b/src/ghdldrv/ghdlrun.adb
@@ -15,26 +15,29 @@
 --  along with GCC; see the file COPYING.  If not, write to the Free
 --  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 --  02111-1307, USA.
+with System; use System;
+
+with Ada.Unchecked_Conversion;
+with Ada.Command_Line;
+with Ada.Text_IO;
+
+with Interfaces;
 with Interfaces.C;
 
 with Ghdlmain; use Ghdlmain;
 with Ghdllocal; use Ghdllocal;
 with GNAT.OS_Lib; use GNAT.OS_Lib;
 
-with Ada.Unchecked_Conversion;
-with Ada.Command_Line;
-with Ada.Text_IO;
-
 with Ortho_Jit;
 with Ortho_Nodes; use Ortho_Nodes;
-with Interfaces;
-with System; use System;
 with Trans_Decls;
 with Iirs; use Iirs;
+with Std_Package;
 with Flags;
 with Errorout; use Errorout;
 with Libraries;
 with Canon;
+with Configuration;
 with Trans_Be;
 with Translation;
 with Ieee.Std_Logic_1164;
@@ -61,7 +64,7 @@ with Grt.Std_Logic_1164;
 with Grt.Errors;
 with Grt.Backtraces.Jit;
 
-with Ghdlcomp;
+with Ghdlcomp; use Ghdlcomp;
 with Foreigns;
 with Grtlink;
 
@@ -84,6 +87,18 @@ package body Ghdlrun is
    procedure Compile_Init (Analyze_Only : Boolean) is
    begin
       if Analyze_Only then
+         Setup_Libraries (True);
+      else
+         Setup_Libraries (False);
+         Libraries.Load_Std_Library;
+         --  WORK library is not loaded.  FIXME: why ?
+      end if;
+
+      if Time_Resolution /= 'a' then
+         Std_Package.Set_Time_Resolution (Time_Resolution);
+      end if;
+
+      if Analyze_Only then
          return;
       end if;
 
@@ -95,9 +110,6 @@ package body Ghdlrun is
       --  The design is always analyzed in whole.
       Flags.Flag_Whole_Analyze := True;
 
-      Setup_Libraries (False);
-      Libraries.Load_Std_Library;
-
       Ortho_Jit.Init;
 
       Translation.Initialize;
@@ -116,6 +128,7 @@ package body Ghdlrun is
    procedure Compile_Elab
      (Cmd_Name : String; Args : Argument_List; Opt_Arg : out Natural)
    is
+      Config : Iir;
    begin
       Extract_Elab_Unit (Cmd_Name, Args, Opt_Arg);
       if Sec_Name = null then
@@ -123,11 +136,44 @@ package body Ghdlrun is
       end if;
 
       Flags.Flag_Elaborate := True;
+
+      Config := Configuration.Configure (Prim_Name.all, Sec_Name.all);
+      if Config = Null_Iir then
+         raise Compilation_Error;
+      end if;
+
+      if Time_Resolution = 'a' then
+         Time_Resolution := Std_Package.Get_Minimal_Time_Resolution;
+         if Time_Resolution = '?' then
+            Time_Resolution := 'f';
+         end if;
+         if Flag_Verbose then
+            declare
+               use Ada.Text_IO;
+            begin
+               Put ("Time resolution is 1 ");
+               case Time_Resolution is
+                  when 'f' => Put ("fs");
+                  when 'p' => Put ("ps");
+                  when 'n' => Put ("ns");
+                  when 'u' => Put ("us");
+                  when 'm' => Put ("ms");
+                  when 's' => Put ("sec");
+                  when 'M' => Put ("min");
+                  when 'h' => Put ("hr");
+                  when others => Put ("??");
+               end case;
+               New_Line;
+            end;
+         end if;
+      end if;
+      Std_Package.Set_Time_Resolution (Time_Resolution);
+
       case Elab_Mode is
          when Elab_Static =>
             raise Program_Error;
          when Elab_Dynamic =>
-            Translation.Elaborate (Prim_Name.all, Sec_Name.all, "", True);
+            Translation.Elaborate (Config, "", True);
       end case;
 
       if Errorout.Nbr_Errors > 0 then
diff --git a/src/grt/grt-main.adb b/src/grt/grt-main.adb
index d50f8d7db..8a0f307b9 100644
--- a/src/grt/grt-main.adb
+++ b/src/grt/grt-main.adb
@@ -112,12 +112,6 @@ package body Grt.Main is
       --  They may insert hooks.
       Grt.Modules.Register_Modules;
 
-      --  If the time resolution is to be set by the user, select a default
-      --  resolution.  Options may override it.
-      if Flag_String (5) = '?' then
-         Set_Time_Resolution ('n');
-      end if;
-
       --  Decode options.
       Grt.Options.Decode (Stop);
 
diff --git a/src/grt/grt-options.adb b/src/grt/grt-options.adb
index 535c0b8a8..3362e5ac1 100644
--- a/src/grt/grt-options.adb
+++ b/src/grt/grt-options.adb
@@ -32,112 +32,6 @@ with Grt.Wave_Opt.File;
 
 package body Grt.Options is
 
-   Std_Standard_Time_Fs : Std_Time;
-   Std_Standard_Time_Ps : Std_Time;
-   Std_Standard_Time_Ns : Std_Time;
-   Std_Standard_Time_Us : Std_Time;
-   Std_Standard_Time_Ms : Std_Time;
-   Std_Standard_Time_Sec : Std_Time;
-   Std_Standard_Time_Min : Std_Time;
-   Std_Standard_Time_Hr : Std_Time;
-   pragma Export (C, Std_Standard_Time_Fs, "std__standard__time__BT__fs");
-   pragma Weak_External (Std_Standard_Time_Fs);
-   pragma Export (C, Std_Standard_Time_Ps, "std__standard__time__BT__ps");
-   pragma Weak_External (Std_Standard_Time_Ps);
-   pragma Export (C, Std_Standard_Time_Ns, "std__standard__time__BT__ns");
-   pragma Weak_External (Std_Standard_Time_Ns);
-   pragma Export (C, Std_Standard_Time_Us, "std__standard__time__BT__us");
-   pragma Weak_External (Std_Standard_Time_Us);
-   pragma Export (C, Std_Standard_Time_Ms, "std__standard__time__BT__ms");
-   pragma Weak_External (Std_Standard_Time_Ms);
-   pragma Export (C, Std_Standard_Time_Sec, "std__standard__time__BT__sec");
-   pragma Weak_External (Std_Standard_Time_Sec);
-   pragma Export (C, Std_Standard_Time_Min, "std__standard__time__BT__min");
-   pragma Weak_External (Std_Standard_Time_Min);
-   pragma Export (C, Std_Standard_Time_Hr, "std__standard__time__BT__hr");
-   pragma Weak_External (Std_Standard_Time_Hr);
-
-   procedure Set_Time_Resolution (Res : Character) is
-   begin
-      Std_Standard_Time_Hr := 0;
-      case Res is
-         when 'f' =>
-            Std_Standard_Time_Fs := 1;
-            Std_Standard_Time_Ps := 1000;
-            Std_Standard_Time_Ns := 1000_000;
-            Std_Standard_Time_Us := 1000_000_000;
-            Std_Standard_Time_Ms := Std_Time'Last;
-            Std_Standard_Time_Sec := Std_Time'Last;
-            Std_Standard_Time_Min := Std_Time'Last;
-            Std_Standard_Time_Hr := Std_Time'Last;
-         when 'p' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 1;
-            Std_Standard_Time_Ns := 1000;
-            Std_Standard_Time_Us := 1000_000;
-            Std_Standard_Time_Ms := 1000_000_000;
-            Std_Standard_Time_Sec := Std_Time'Last;
-            Std_Standard_Time_Min := Std_Time'Last;
-            Std_Standard_Time_Hr := Std_Time'Last;
-         when 'n' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 1;
-            Std_Standard_Time_Us := 1000;
-            Std_Standard_Time_Ms := 1000_000;
-            Std_Standard_Time_Sec := 1000_000_000;
-            Std_Standard_Time_Min := Std_Time'Last;
-            Std_Standard_Time_Hr := Std_Time'Last;
-         when 'u' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 0;
-            Std_Standard_Time_Us := 1;
-            Std_Standard_Time_Ms := 1000;
-            Std_Standard_Time_Sec := 1000_000;
-            Std_Standard_Time_Min := 60_000_000;
-            Std_Standard_Time_Hr := Std_Time'Last;
-         when 'm' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 0;
-            Std_Standard_Time_Us := 0;
-            Std_Standard_Time_Ms := 1;
-            Std_Standard_Time_Sec := 1000;
-            Std_Standard_Time_Min := 60_000;
-            Std_Standard_Time_Hr := 3600_000;
-         when 's' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 0;
-            Std_Standard_Time_Us := 0;
-            Std_Standard_Time_Ms := 0;
-            Std_Standard_Time_Sec := 1;
-            Std_Standard_Time_Min := 60;
-            Std_Standard_Time_Hr := 3600;
-         when 'M' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 0;
-            Std_Standard_Time_Us := 0;
-            Std_Standard_Time_Ms := 0;
-            Std_Standard_Time_Sec := 0;
-            Std_Standard_Time_Min := 1;
-            Std_Standard_Time_Hr := 60;
-         when 'h' =>
-            Std_Standard_Time_Fs := 0;
-            Std_Standard_Time_Ps := 0;
-            Std_Standard_Time_Ns := 0;
-            Std_Standard_Time_Us := 0;
-            Std_Standard_Time_Ms := 0;
-            Std_Standard_Time_Sec := 0;
-            Std_Standard_Time_Min := 0;
-            Std_Standard_Time_Hr := 1;
-         when others =>
-            Error ("bad time resolution");
-      end case;
-   end Set_Time_Resolution;
-
    procedure Help
    is
       use Grt.Astdio;
@@ -316,57 +210,6 @@ package body Grt.Options is
          Flag_Stats := True;
       elsif Option = "--no-run" then
          Flag_No_Run := True;
-      elsif Len > 18 and then Option (1 .. 18) = "--time-resolution=" then
-         declare
-            Res : Character;
-            Unit : String (1 .. 3);
-         begin
-            Res := '?';
-            if Len >= 20 then
-               Unit (1) := To_Lower (Option (19));
-               Unit (2) := To_Lower (Option (20));
-               if Len = 20 then
-                  if Unit (1 .. 2) = "fs" then
-                     Res := 'f';
-                  elsif Unit (1 .. 2) = "ps" then
-                     Res := 'p';
-                  elsif Unit (1 .. 2) = "ns" then
-                     Res := 'n';
-                  elsif Unit (1 .. 2) = "us" then
-                     Res := 'u';
-                  elsif Unit (1 .. 2) = "ms" then
-                     Res := 'm';
-                  elsif Unit (1 .. 2) = "hr" then
-                     Res := 'h';
-                  end if;
-               elsif Len = 21 then
-                  Unit (3) := To_Lower (Option (21));
-                  if Unit = "min" then
-                     Res := 'M';
-                  elsif Unit = "sec" then
-                     Res := 's';
-                  end if;
-               end if;
-            end if;
-            if Res = '?' then
-               Error_C ("bad unit for '");
-               Error_C (Option);
-               Error_E ("'");
-            else
-               if Flag_String (5) = '-' then
-                  Error ("time resolution is ignored");
-               elsif Flag_String (5) = '?' then
-                  if Stop_Time /= Std_Time'First then
-                     Error ("time resolution must be set "
-                              & "before --stop-time");
-                  else
-                     Set_Time_Resolution (Res);
-                  end if;
-               elsif Flag_String (5) /= Res then
-                  Error ("time resolution is fixed during analysis");
-               end if;
-            end if;
-         end;
       elsif Len > 12 and then Option (1 .. 12) = "--stop-time=" then
          Stop_Time := Parse_Time (Option (13 .. Len));
          if Stop_Time = -1 then
diff --git a/src/grt/grt-options.ads b/src/grt/grt-options.ads
index 78fe9d8d7..4f24793f0 100644
--- a/src/grt/grt-options.ads
+++ b/src/grt/grt-options.ads
@@ -149,10 +149,6 @@ package Grt.Options is
    --  message and returns -1.
    function Parse_Time (Str : String) return Std_Time;
 
-   --  Set the time resolution.
-   --  Only call this subprogram if you are allowed to set the time resolution.
-   procedure Set_Time_Resolution (Res : Character);
-
    --  Simply linked list of generic override (option -gIDENT=VALUE).
    type Generic_Override_Type;
    type Generic_Override_Acc is access Generic_Override_Type;
diff --git a/src/options.adb b/src/options.adb
index 9c752da87..43f68bbb5 100644
--- a/src/options.adb
+++ b/src/options.adb
@@ -200,29 +200,6 @@ package body Options is
          Flag_Integer_64 := True;
       elsif Opt = "--ftime32" then
          Flag_Time_64 := False;
---       elsif Opt'Length > 17
---         and then Opt (Beg .. Beg + 17) = "--time-resolution="
---       then
---          Beg := Beg + 18;
---          if Opt (Beg .. Beg + 1) = "fs" then
---             Time_Resolution := 'f';
---          elsif Opt (Beg .. Beg + 1) = "ps" then
---             Time_Resolution := 'p';
---          elsif Opt (Beg .. Beg + 1) = "ns" then
---             Time_Resolution := 'n';
---          elsif Opt (Beg .. Beg + 1) = "us" then
---             Time_Resolution := 'u';
---          elsif Opt (Beg .. Beg + 1) = "ms" then
---             Time_Resolution := 'm';
---          elsif Opt (Beg .. Beg + 2) = "sec" then
---             Time_Resolution := 's';
---          elsif Opt (Beg .. Beg + 2) = "min" then
---             Time_Resolution := 'M';
---          elsif Opt (Beg .. Beg + 1) = "hr" then
---             Time_Resolution := 'h';
---          else
---             return False;
---          end if;
       elsif Back_End.Parse_Option /= null
         and then Back_End.Parse_Option.all (Opt)
       then
@@ -257,8 +234,6 @@ package body Options is
       P ("  -Wunused           warns if a subprogram is never used");
       P ("  -Werror            turns warnings into errors");
 --    P ("Simulation option:");
---    P ("  --time-resolution=UNIT   set the resolution of type time");
---    P ("            UNIT can be fs, ps, ns, us, ms, sec, min or hr");
 --    P ("  --assert-level=LEVEL     set the level which stop the");
 --    P ("           simulation.  LEVEL is note, warning, error,");
 --    P ("           failure or none");
diff --git a/src/vhdl/iirs.ads b/src/vhdl/iirs.ads
index f7985f6d4..33ac760f0 100644
--- a/src/vhdl/iirs.ads
+++ b/src/vhdl/iirs.ads
@@ -2162,6 +2162,9 @@ package Iirs is
    --   Get/Set_Name_Staticness (State2)
    --
    --   Get/Set_Visible_Flag (Flag4)
+   --
+   --  Used for time literals, to compute minimal resolution.
+   --   Get/Set_Use_Flag (Flag6)
 
    --  LRM08 5.2 Scalar types
    --
@@ -4966,6 +4969,10 @@ package Iirs is
    --Iir_Kind_Physical_Int_Literal
      Iir_Kind_Physical_Fp_Literal;
 
+   subtype Iir_Kinds_Physical_Literal is Iir_Kind range
+     Iir_Kind_Physical_Int_Literal ..
+     Iir_Kind_Physical_Fp_Literal;
+
    subtype Iir_Kinds_Array_Type_Definition is Iir_Kind range
      Iir_Kind_Array_Type_Definition ..
      Iir_Kind_Array_Subtype_Definition;
diff --git a/src/vhdl/nodes_meta.adb b/src/vhdl/nodes_meta.adb
index fe1b2353b..b14c47b93 100644
--- a/src/vhdl/nodes_meta.adb
+++ b/src/vhdl/nodes_meta.adb
@@ -2864,6 +2864,7 @@ package body Nodes_Meta is
       --  Iir_Kind_Unit_Declaration
       Field_Identifier,
       Field_Visible_Flag,
+      Field_Use_Flag,
       Field_Expr_Staticness,
       Field_Name_Staticness,
       Field_Parent,
@@ -4482,189 +4483,189 @@ package body Nodes_Meta is
       Iir_Kind_Package_Body => 551,
       Iir_Kind_Architecture_Body => 563,
       Iir_Kind_Package_Header => 565,
-      Iir_Kind_Unit_Declaration => 573,
-      Iir_Kind_Library_Declaration => 580,
-      Iir_Kind_Component_Declaration => 590,
-      Iir_Kind_Attribute_Declaration => 597,
-      Iir_Kind_Group_Template_Declaration => 603,
-      Iir_Kind_Group_Declaration => 610,
-      Iir_Kind_Element_Declaration => 618,
-      Iir_Kind_Non_Object_Alias_Declaration => 626,
-      Iir_Kind_Psl_Declaration => 634,
-      Iir_Kind_Psl_Endpoint_Declaration => 648,
-      Iir_Kind_Terminal_Declaration => 654,
-      Iir_Kind_Free_Quantity_Declaration => 663,
-      Iir_Kind_Across_Quantity_Declaration => 675,
-      Iir_Kind_Through_Quantity_Declaration => 687,
-      Iir_Kind_Enumeration_Literal => 698,
-      Iir_Kind_Function_Declaration => 723,
-      Iir_Kind_Procedure_Declaration => 747,
-      Iir_Kind_Function_Body => 757,
-      Iir_Kind_Procedure_Body => 768,
-      Iir_Kind_Object_Alias_Declaration => 779,
-      Iir_Kind_File_Declaration => 793,
-      Iir_Kind_Guard_Signal_Declaration => 806,
-      Iir_Kind_Signal_Declaration => 823,
-      Iir_Kind_Variable_Declaration => 836,
-      Iir_Kind_Constant_Declaration => 850,
-      Iir_Kind_Iterator_Declaration => 861,
-      Iir_Kind_Interface_Constant_Declaration => 877,
-      Iir_Kind_Interface_Variable_Declaration => 893,
-      Iir_Kind_Interface_Signal_Declaration => 914,
-      Iir_Kind_Interface_File_Declaration => 930,
-      Iir_Kind_Interface_Type_Declaration => 940,
-      Iir_Kind_Interface_Package_Declaration => 952,
-      Iir_Kind_Interface_Function_Declaration => 969,
-      Iir_Kind_Interface_Procedure_Declaration => 982,
-      Iir_Kind_Signal_Attribute_Declaration => 985,
-      Iir_Kind_Identity_Operator => 989,
-      Iir_Kind_Negation_Operator => 993,
-      Iir_Kind_Absolute_Operator => 997,
-      Iir_Kind_Not_Operator => 1001,
-      Iir_Kind_Implicit_Condition_Operator => 1005,
-      Iir_Kind_Condition_Operator => 1009,
-      Iir_Kind_Reduction_And_Operator => 1013,
-      Iir_Kind_Reduction_Or_Operator => 1017,
-      Iir_Kind_Reduction_Nand_Operator => 1021,
-      Iir_Kind_Reduction_Nor_Operator => 1025,
-      Iir_Kind_Reduction_Xor_Operator => 1029,
-      Iir_Kind_Reduction_Xnor_Operator => 1033,
-      Iir_Kind_And_Operator => 1038,
-      Iir_Kind_Or_Operator => 1043,
-      Iir_Kind_Nand_Operator => 1048,
-      Iir_Kind_Nor_Operator => 1053,
-      Iir_Kind_Xor_Operator => 1058,
-      Iir_Kind_Xnor_Operator => 1063,
-      Iir_Kind_Equality_Operator => 1068,
-      Iir_Kind_Inequality_Operator => 1073,
-      Iir_Kind_Less_Than_Operator => 1078,
-      Iir_Kind_Less_Than_Or_Equal_Operator => 1083,
-      Iir_Kind_Greater_Than_Operator => 1088,
-      Iir_Kind_Greater_Than_Or_Equal_Operator => 1093,
-      Iir_Kind_Match_Equality_Operator => 1098,
-      Iir_Kind_Match_Inequality_Operator => 1103,
-      Iir_Kind_Match_Less_Than_Operator => 1108,
-      Iir_Kind_Match_Less_Than_Or_Equal_Operator => 1113,
-      Iir_Kind_Match_Greater_Than_Operator => 1118,
-      Iir_Kind_Match_Greater_Than_Or_Equal_Operator => 1123,
-      Iir_Kind_Sll_Operator => 1128,
-      Iir_Kind_Sla_Operator => 1133,
-      Iir_Kind_Srl_Operator => 1138,
-      Iir_Kind_Sra_Operator => 1143,
-      Iir_Kind_Rol_Operator => 1148,
-      Iir_Kind_Ror_Operator => 1153,
-      Iir_Kind_Addition_Operator => 1158,
-      Iir_Kind_Substraction_Operator => 1163,
-      Iir_Kind_Concatenation_Operator => 1168,
-      Iir_Kind_Multiplication_Operator => 1173,
-      Iir_Kind_Division_Operator => 1178,
-      Iir_Kind_Modulus_Operator => 1183,
-      Iir_Kind_Remainder_Operator => 1188,
-      Iir_Kind_Exponentiation_Operator => 1193,
-      Iir_Kind_Function_Call => 1201,
-      Iir_Kind_Aggregate => 1208,
-      Iir_Kind_Parenthesis_Expression => 1211,
-      Iir_Kind_Qualified_Expression => 1215,
-      Iir_Kind_Type_Conversion => 1220,
-      Iir_Kind_Allocator_By_Expression => 1224,
-      Iir_Kind_Allocator_By_Subtype => 1229,
-      Iir_Kind_Selected_Element => 1236,
-      Iir_Kind_Dereference => 1241,
-      Iir_Kind_Implicit_Dereference => 1246,
-      Iir_Kind_Slice_Name => 1253,
-      Iir_Kind_Indexed_Name => 1259,
-      Iir_Kind_Psl_Expression => 1261,
-      Iir_Kind_Sensitized_Process_Statement => 1282,
-      Iir_Kind_Process_Statement => 1302,
-      Iir_Kind_Concurrent_Simple_Signal_Assignment => 1314,
-      Iir_Kind_Concurrent_Conditional_Signal_Assignment => 1326,
-      Iir_Kind_Concurrent_Selected_Signal_Assignment => 1339,
-      Iir_Kind_Concurrent_Assertion_Statement => 1347,
-      Iir_Kind_Concurrent_Procedure_Call_Statement => 1354,
-      Iir_Kind_Psl_Assert_Statement => 1367,
-      Iir_Kind_Psl_Cover_Statement => 1380,
-      Iir_Kind_Block_Statement => 1393,
-      Iir_Kind_If_Generate_Statement => 1404,
-      Iir_Kind_Case_Generate_Statement => 1413,
-      Iir_Kind_For_Generate_Statement => 1422,
-      Iir_Kind_Component_Instantiation_Statement => 1433,
-      Iir_Kind_Psl_Default_Clock => 1437,
-      Iir_Kind_Simple_Simultaneous_Statement => 1444,
-      Iir_Kind_Generate_Statement_Body => 1455,
-      Iir_Kind_If_Generate_Else_Clause => 1461,
-      Iir_Kind_Simple_Signal_Assignment_Statement => 1471,
-      Iir_Kind_Conditional_Signal_Assignment_Statement => 1481,
-      Iir_Kind_Selected_Waveform_Assignment_Statement => 1492,
-      Iir_Kind_Null_Statement => 1496,
-      Iir_Kind_Assertion_Statement => 1503,
-      Iir_Kind_Report_Statement => 1509,
-      Iir_Kind_Wait_Statement => 1517,
-      Iir_Kind_Variable_Assignment_Statement => 1524,
-      Iir_Kind_Conditional_Variable_Assignment_Statement => 1531,
-      Iir_Kind_Return_Statement => 1537,
-      Iir_Kind_For_Loop_Statement => 1546,
-      Iir_Kind_While_Loop_Statement => 1555,
-      Iir_Kind_Next_Statement => 1562,
-      Iir_Kind_Exit_Statement => 1569,
-      Iir_Kind_Case_Statement => 1577,
-      Iir_Kind_Procedure_Call_Statement => 1583,
-      Iir_Kind_If_Statement => 1593,
-      Iir_Kind_Elsif => 1599,
-      Iir_Kind_Character_Literal => 1607,
-      Iir_Kind_Simple_Name => 1615,
-      Iir_Kind_Selected_Name => 1624,
-      Iir_Kind_Operator_Symbol => 1630,
-      Iir_Kind_Reference_Name => 1633,
-      Iir_Kind_External_Constant_Name => 1642,
-      Iir_Kind_External_Signal_Name => 1651,
-      Iir_Kind_External_Variable_Name => 1660,
-      Iir_Kind_Selected_By_All_Name => 1666,
-      Iir_Kind_Parenthesis_Name => 1671,
-      Iir_Kind_Package_Pathname => 1675,
-      Iir_Kind_Absolute_Pathname => 1676,
-      Iir_Kind_Relative_Pathname => 1677,
-      Iir_Kind_Pathname_Element => 1682,
-      Iir_Kind_Base_Attribute => 1684,
-      Iir_Kind_Subtype_Attribute => 1689,
-      Iir_Kind_Element_Attribute => 1694,
-      Iir_Kind_Left_Type_Attribute => 1699,
-      Iir_Kind_Right_Type_Attribute => 1704,
-      Iir_Kind_High_Type_Attribute => 1709,
-      Iir_Kind_Low_Type_Attribute => 1714,
-      Iir_Kind_Ascending_Type_Attribute => 1719,
-      Iir_Kind_Image_Attribute => 1725,
-      Iir_Kind_Value_Attribute => 1731,
-      Iir_Kind_Pos_Attribute => 1737,
-      Iir_Kind_Val_Attribute => 1743,
-      Iir_Kind_Succ_Attribute => 1749,
-      Iir_Kind_Pred_Attribute => 1755,
-      Iir_Kind_Leftof_Attribute => 1761,
-      Iir_Kind_Rightof_Attribute => 1767,
-      Iir_Kind_Delayed_Attribute => 1776,
-      Iir_Kind_Stable_Attribute => 1785,
-      Iir_Kind_Quiet_Attribute => 1794,
-      Iir_Kind_Transaction_Attribute => 1803,
-      Iir_Kind_Event_Attribute => 1807,
-      Iir_Kind_Active_Attribute => 1811,
-      Iir_Kind_Last_Event_Attribute => 1815,
-      Iir_Kind_Last_Active_Attribute => 1819,
-      Iir_Kind_Last_Value_Attribute => 1823,
-      Iir_Kind_Driving_Attribute => 1827,
-      Iir_Kind_Driving_Value_Attribute => 1831,
-      Iir_Kind_Behavior_Attribute => 1831,
-      Iir_Kind_Structure_Attribute => 1831,
-      Iir_Kind_Simple_Name_Attribute => 1838,
-      Iir_Kind_Instance_Name_Attribute => 1843,
-      Iir_Kind_Path_Name_Attribute => 1848,
-      Iir_Kind_Left_Array_Attribute => 1855,
-      Iir_Kind_Right_Array_Attribute => 1862,
-      Iir_Kind_High_Array_Attribute => 1869,
-      Iir_Kind_Low_Array_Attribute => 1876,
-      Iir_Kind_Length_Array_Attribute => 1883,
-      Iir_Kind_Ascending_Array_Attribute => 1890,
-      Iir_Kind_Range_Array_Attribute => 1897,
-      Iir_Kind_Reverse_Range_Array_Attribute => 1904,
-      Iir_Kind_Attribute_Name => 1913
+      Iir_Kind_Unit_Declaration => 574,
+      Iir_Kind_Library_Declaration => 581,
+      Iir_Kind_Component_Declaration => 591,
+      Iir_Kind_Attribute_Declaration => 598,
+      Iir_Kind_Group_Template_Declaration => 604,
+      Iir_Kind_Group_Declaration => 611,
+      Iir_Kind_Element_Declaration => 619,
+      Iir_Kind_Non_Object_Alias_Declaration => 627,
+      Iir_Kind_Psl_Declaration => 635,
+      Iir_Kind_Psl_Endpoint_Declaration => 649,
+      Iir_Kind_Terminal_Declaration => 655,
+      Iir_Kind_Free_Quantity_Declaration => 664,
+      Iir_Kind_Across_Quantity_Declaration => 676,
+      Iir_Kind_Through_Quantity_Declaration => 688,
+      Iir_Kind_Enumeration_Literal => 699,
+      Iir_Kind_Function_Declaration => 724,
+      Iir_Kind_Procedure_Declaration => 748,
+      Iir_Kind_Function_Body => 758,
+      Iir_Kind_Procedure_Body => 769,
+      Iir_Kind_Object_Alias_Declaration => 780,
+      Iir_Kind_File_Declaration => 794,
+      Iir_Kind_Guard_Signal_Declaration => 807,
+      Iir_Kind_Signal_Declaration => 824,
+      Iir_Kind_Variable_Declaration => 837,
+      Iir_Kind_Constant_Declaration => 851,
+      Iir_Kind_Iterator_Declaration => 862,
+      Iir_Kind_Interface_Constant_Declaration => 878,
+      Iir_Kind_Interface_Variable_Declaration => 894,
+      Iir_Kind_Interface_Signal_Declaration => 915,
+      Iir_Kind_Interface_File_Declaration => 931,
+      Iir_Kind_Interface_Type_Declaration => 941,
+      Iir_Kind_Interface_Package_Declaration => 953,
+      Iir_Kind_Interface_Function_Declaration => 970,
+      Iir_Kind_Interface_Procedure_Declaration => 983,
+      Iir_Kind_Signal_Attribute_Declaration => 986,
+      Iir_Kind_Identity_Operator => 990,
+      Iir_Kind_Negation_Operator => 994,
+      Iir_Kind_Absolute_Operator => 998,
+      Iir_Kind_Not_Operator => 1002,
+      Iir_Kind_Implicit_Condition_Operator => 1006,
+      Iir_Kind_Condition_Operator => 1010,
+      Iir_Kind_Reduction_And_Operator => 1014,
+      Iir_Kind_Reduction_Or_Operator => 1018,
+      Iir_Kind_Reduction_Nand_Operator => 1022,
+      Iir_Kind_Reduction_Nor_Operator => 1026,
+      Iir_Kind_Reduction_Xor_Operator => 1030,
+      Iir_Kind_Reduction_Xnor_Operator => 1034,
+      Iir_Kind_And_Operator => 1039,
+      Iir_Kind_Or_Operator => 1044,
+      Iir_Kind_Nand_Operator => 1049,
+      Iir_Kind_Nor_Operator => 1054,
+      Iir_Kind_Xor_Operator => 1059,
+      Iir_Kind_Xnor_Operator => 1064,
+      Iir_Kind_Equality_Operator => 1069,
+      Iir_Kind_Inequality_Operator => 1074,
+      Iir_Kind_Less_Than_Operator => 1079,
+      Iir_Kind_Less_Than_Or_Equal_Operator => 1084,
+      Iir_Kind_Greater_Than_Operator => 1089,
+      Iir_Kind_Greater_Than_Or_Equal_Operator => 1094,
+      Iir_Kind_Match_Equality_Operator => 1099,
+      Iir_Kind_Match_Inequality_Operator => 1104,
+      Iir_Kind_Match_Less_Than_Operator => 1109,
+      Iir_Kind_Match_Less_Than_Or_Equal_Operator => 1114,
+      Iir_Kind_Match_Greater_Than_Operator => 1119,
+      Iir_Kind_Match_Greater_Than_Or_Equal_Operator => 1124,
+      Iir_Kind_Sll_Operator => 1129,
+      Iir_Kind_Sla_Operator => 1134,
+      Iir_Kind_Srl_Operator => 1139,
+      Iir_Kind_Sra_Operator => 1144,
+      Iir_Kind_Rol_Operator => 1149,
+      Iir_Kind_Ror_Operator => 1154,
+      Iir_Kind_Addition_Operator => 1159,
+      Iir_Kind_Substraction_Operator => 1164,
+      Iir_Kind_Concatenation_Operator => 1169,
+      Iir_Kind_Multiplication_Operator => 1174,
+      Iir_Kind_Division_Operator => 1179,
+      Iir_Kind_Modulus_Operator => 1184,
+      Iir_Kind_Remainder_Operator => 1189,
+      Iir_Kind_Exponentiation_Operator => 1194,
+      Iir_Kind_Function_Call => 1202,
+      Iir_Kind_Aggregate => 1209,
+      Iir_Kind_Parenthesis_Expression => 1212,
+      Iir_Kind_Qualified_Expression => 1216,
+      Iir_Kind_Type_Conversion => 1221,
+      Iir_Kind_Allocator_By_Expression => 1225,
+      Iir_Kind_Allocator_By_Subtype => 1230,
+      Iir_Kind_Selected_Element => 1237,
+      Iir_Kind_Dereference => 1242,
+      Iir_Kind_Implicit_Dereference => 1247,
+      Iir_Kind_Slice_Name => 1254,
+      Iir_Kind_Indexed_Name => 1260,
+      Iir_Kind_Psl_Expression => 1262,
+      Iir_Kind_Sensitized_Process_Statement => 1283,
+      Iir_Kind_Process_Statement => 1303,
+      Iir_Kind_Concurrent_Simple_Signal_Assignment => 1315,
+      Iir_Kind_Concurrent_Conditional_Signal_Assignment => 1327,
+      Iir_Kind_Concurrent_Selected_Signal_Assignment => 1340,
+      Iir_Kind_Concurrent_Assertion_Statement => 1348,
+      Iir_Kind_Concurrent_Procedure_Call_Statement => 1355,
+      Iir_Kind_Psl_Assert_Statement => 1368,
+      Iir_Kind_Psl_Cover_Statement => 1381,
+      Iir_Kind_Block_Statement => 1394,
+      Iir_Kind_If_Generate_Statement => 1405,
+      Iir_Kind_Case_Generate_Statement => 1414,
+      Iir_Kind_For_Generate_Statement => 1423,
+      Iir_Kind_Component_Instantiation_Statement => 1434,
+      Iir_Kind_Psl_Default_Clock => 1438,
+      Iir_Kind_Simple_Simultaneous_Statement => 1445,
+      Iir_Kind_Generate_Statement_Body => 1456,
+      Iir_Kind_If_Generate_Else_Clause => 1462,
+      Iir_Kind_Simple_Signal_Assignment_Statement => 1472,
+      Iir_Kind_Conditional_Signal_Assignment_Statement => 1482,
+      Iir_Kind_Selected_Waveform_Assignment_Statement => 1493,
+      Iir_Kind_Null_Statement => 1497,
+      Iir_Kind_Assertion_Statement => 1504,
+      Iir_Kind_Report_Statement => 1510,
+      Iir_Kind_Wait_Statement => 1518,
+      Iir_Kind_Variable_Assignment_Statement => 1525,
+      Iir_Kind_Conditional_Variable_Assignment_Statement => 1532,
+      Iir_Kind_Return_Statement => 1538,
+      Iir_Kind_For_Loop_Statement => 1547,
+      Iir_Kind_While_Loop_Statement => 1556,
+      Iir_Kind_Next_Statement => 1563,
+      Iir_Kind_Exit_Statement => 1570,
+      Iir_Kind_Case_Statement => 1578,
+      Iir_Kind_Procedure_Call_Statement => 1584,
+      Iir_Kind_If_Statement => 1594,
+      Iir_Kind_Elsif => 1600,
+      Iir_Kind_Character_Literal => 1608,
+      Iir_Kind_Simple_Name => 1616,
+      Iir_Kind_Selected_Name => 1625,
+      Iir_Kind_Operator_Symbol => 1631,
+      Iir_Kind_Reference_Name => 1634,
+      Iir_Kind_External_Constant_Name => 1643,
+      Iir_Kind_External_Signal_Name => 1652,
+      Iir_Kind_External_Variable_Name => 1661,
+      Iir_Kind_Selected_By_All_Name => 1667,
+      Iir_Kind_Parenthesis_Name => 1672,
+      Iir_Kind_Package_Pathname => 1676,
+      Iir_Kind_Absolute_Pathname => 1677,
+      Iir_Kind_Relative_Pathname => 1678,
+      Iir_Kind_Pathname_Element => 1683,
+      Iir_Kind_Base_Attribute => 1685,
+      Iir_Kind_Subtype_Attribute => 1690,
+      Iir_Kind_Element_Attribute => 1695,
+      Iir_Kind_Left_Type_Attribute => 1700,
+      Iir_Kind_Right_Type_Attribute => 1705,
+      Iir_Kind_High_Type_Attribute => 1710,
+      Iir_Kind_Low_Type_Attribute => 1715,
+      Iir_Kind_Ascending_Type_Attribute => 1720,
+      Iir_Kind_Image_Attribute => 1726,
+      Iir_Kind_Value_Attribute => 1732,
+      Iir_Kind_Pos_Attribute => 1738,
+      Iir_Kind_Val_Attribute => 1744,
+      Iir_Kind_Succ_Attribute => 1750,
+      Iir_Kind_Pred_Attribute => 1756,
+      Iir_Kind_Leftof_Attribute => 1762,
+      Iir_Kind_Rightof_Attribute => 1768,
+      Iir_Kind_Delayed_Attribute => 1777,
+      Iir_Kind_Stable_Attribute => 1786,
+      Iir_Kind_Quiet_Attribute => 1795,
+      Iir_Kind_Transaction_Attribute => 1804,
+      Iir_Kind_Event_Attribute => 1808,
+      Iir_Kind_Active_Attribute => 1812,
+      Iir_Kind_Last_Event_Attribute => 1816,
+      Iir_Kind_Last_Active_Attribute => 1820,
+      Iir_Kind_Last_Value_Attribute => 1824,
+      Iir_Kind_Driving_Attribute => 1828,
+      Iir_Kind_Driving_Value_Attribute => 1832,
+      Iir_Kind_Behavior_Attribute => 1832,
+      Iir_Kind_Structure_Attribute => 1832,
+      Iir_Kind_Simple_Name_Attribute => 1839,
+      Iir_Kind_Instance_Name_Attribute => 1844,
+      Iir_Kind_Path_Name_Attribute => 1849,
+      Iir_Kind_Left_Array_Attribute => 1856,
+      Iir_Kind_Right_Array_Attribute => 1863,
+      Iir_Kind_High_Array_Attribute => 1870,
+      Iir_Kind_Low_Array_Attribute => 1877,
+      Iir_Kind_Length_Array_Attribute => 1884,
+      Iir_Kind_Ascending_Array_Attribute => 1891,
+      Iir_Kind_Range_Array_Attribute => 1898,
+      Iir_Kind_Reverse_Range_Array_Attribute => 1905,
+      Iir_Kind_Attribute_Name => 1914
      );
 
    function Get_Fields_First (K : Iir_Kind) return Fields_Index is
@@ -10311,6 +10312,7 @@ package body Nodes_Meta is
            | Iir_Kind_Subtype_Declaration
            | Iir_Kind_Nature_Declaration
            | Iir_Kind_Subnature_Declaration
+           | Iir_Kind_Unit_Declaration
            | Iir_Kind_Component_Declaration
            | Iir_Kind_Attribute_Declaration
            | Iir_Kind_Group_Template_Declaration
diff --git a/src/vhdl/sem_expr.adb b/src/vhdl/sem_expr.adb
index 92dcc408a..5fa1e91c3 100644
--- a/src/vhdl/sem_expr.adb
+++ b/src/vhdl/sem_expr.adb
@@ -3593,10 +3593,20 @@ package body Sem_Expr is
       end case;
    end Sem_Aggregate;
 
-   -- Transform LIT into a physical_literal.
-   -- LIT can be either a not analyzed physical literal or
-   --  a simple name that is a physical unit.  In the later case, a physical
-   --  literal is created.
+   function Is_Physical_Literal_Zero (Lit : Iir) return Boolean is
+   begin
+      case Iir_Kinds_Physical_Literal (Get_Kind (Lit)) is
+         when Iir_Kind_Physical_Int_Literal =>
+            return Get_Value (Lit) = 0;
+         when Iir_Kind_Physical_Fp_Literal =>
+            return Get_Fp_Value (Lit) = 0.0;
+      end case;
+   end Is_Physical_Literal_Zero;
+
+   --  Transform LIT into a physical_literal.
+   --  LIT can be either a not analyzed physical literal or
+   --   a simple name that is a physical unit.  In the later case, a physical
+   --   literal is created.
    function Sem_Physical_Literal (Lit: Iir) return Iir
    is
       Unit_Name : Iir;
@@ -3625,17 +3635,36 @@ package body Sem_Expr is
             Error_Class_Match (Unit_Name, "unit");
          end if;
          Set_Named_Entity (Unit_Name, Create_Error_Name (Unit_Name));
+      else
+         --  Physical unit is used.
+         Set_Use_Flag (Unit, True);
+
+         if Get_Type (Unit) = Time_Type_Definition
+           and then Get_Value (Get_Physical_Literal (Unit)) = 0
+           and then not Is_Physical_Literal_Zero (Res)
+         then
+            --  LRM08 5.2.4.2 Predefined physical types
+            --  It is an error if a given unit of type TIME appears anywhere
+            --  within the design hierarchy defining a model to be elaborated,
+            --  and if the position number of that unit is less than that of
+            --  the secondary unit selected as the resolution limit for type
+            --  TIME during the elaboration of the model, unless that unit is
+            --  part of a physical literal whose abstract literal is either
+            --  the integer value zero or the floating-point value zero.
+            Error_Msg_Sem
+              (+Res, "physical unit %i is below the time resolution", +Unit);
+         end if;
       end if;
       Set_Unit_Name (Res, Unit_Name);
       Set_Physical_Unit (Res, Get_Named_Entity (Unit_Name));
       Unit_Type := Get_Type (Unit_Name);
       Set_Type (Res, Unit_Type);
 
-      -- LRM93 7.4.2
-      -- 1. a literal of type TIME.
+      --  LRM93 7.4.2
+      --  1. a literal of type TIME.
       --
-      -- LRM93 7.4.1
-      -- 1. a literal of any type other than type TIME;
+      --  LRM93 7.4.1
+      --  1. a literal of any type other than type TIME;
       Set_Expr_Staticness (Res, Get_Expr_Staticness (Unit_Name));
       --Eval_Check_Constraints (Res);
       return Res;
diff --git a/src/vhdl/simulate/simul-execution.adb b/src/vhdl/simulate/simul-execution.adb
index 0958462a5..451889bc9 100644
--- a/src/vhdl/simulate/simul-execution.adb
+++ b/src/vhdl/simulate/simul-execution.adb
@@ -3831,9 +3831,7 @@ package body Simul.Execution is
    begin
       case Get_Identifier (Imp) is
          when Std_Names.Name_Get_Resolution_Limit =>
-            Res := Create_I64_Value
-              (Ghdl_I64
-                 (Evaluation.Get_Physical_Value (Std_Package.Time_Base)));
+            Res := Create_I64_Value (1);
          when Std_Names.Name_Textio_Read_Real =>
             Res := Create_F64_Value
               (File_Operation.Textio_Read_Real (Block.Objects (1)));
diff --git a/src/vhdl/std_package.adb b/src/vhdl/std_package.adb
index 6d1456b7d..04c17ce22 100644
--- a/src/vhdl/std_package.adb
+++ b/src/vhdl/std_package.adb
@@ -36,6 +36,16 @@ package body Std_Package is
    Std_Location: Location_Type := Location_Nil;
    Std_Filename : Name_Id := Null_Identifier;
 
+   --  Could be public.
+   Time_Fs_Unit: Iir_Unit_Declaration;
+   Time_Ps_Unit: Iir_Unit_Declaration;
+   Time_Ns_Unit: Iir_Unit_Declaration;
+   Time_Us_Unit: Iir_Unit_Declaration;
+   Time_Ms_Unit: Iir_Unit_Declaration;
+   Time_Sec_Unit: Iir_Unit_Declaration;
+   Time_Min_Unit: Iir_Unit_Declaration;
+   Time_Hr_Unit: Iir_Unit_Declaration;
+
    function Create_Std_Iir (Kind : Iir_Kind) return Iir
    is
       Res : Iir;
@@ -824,14 +834,6 @@ package body Std_Package is
             Append (Last_Unit, Time_Type_Definition, Unit);
          end Create_Unit;
 
-         Time_Fs_Unit: Iir_Unit_Declaration;
-         Time_Ps_Unit: Iir_Unit_Declaration;
-         Time_Ns_Unit: Iir_Unit_Declaration;
-         Time_Us_Unit: Iir_Unit_Declaration;
-         Time_Ms_Unit: Iir_Unit_Declaration;
-         Time_Sec_Unit: Iir_Unit_Declaration;
-         Time_Min_Unit: Iir_Unit_Declaration;
-         Time_Hr_Unit: Iir_Unit_Declaration;
          Constraint : Iir_Range_Expression;
       begin
          if Vhdl_Std >= Vhdl_93c then
@@ -908,28 +910,6 @@ package body Std_Package is
          Set_Subtype_Definition
            (Time_Type_Declaration, Time_Subtype_Definition);
 
-         -- The default time base.
-         case Flags.Time_Resolution is
-            when 'f' =>
-               Time_Base := Time_Fs_Unit;
-            when 'p' =>
-               Time_Base := Time_Ps_Unit;
-            when 'n' =>
-               Time_Base := Time_Ns_Unit;
-            when 'u' =>
-               Time_Base := Time_Us_Unit;
-            when 'm' =>
-               Time_Base := Time_Ms_Unit;
-            when 's' =>
-               Time_Base := Time_Sec_Unit;
-            when 'M' =>
-               Time_Base := Time_Min_Unit;
-            when 'h' =>
-               Time_Base := Time_Hr_Unit;
-            when others =>
-               raise Internal_Error;
-         end case;
-
          --  VHDL93
          --  subtype DELAY_LENGTH is TIME range 0 to TIME'HIGH
          if Vhdl_Std >= Vhdl_93c then
@@ -1280,4 +1260,94 @@ package body Std_Package is
       Set_Error_Origin (Error_Type, Null_Iir);
       Create_Wildcard_Type (Error_Type, "unknown type");
    end Create_Std_Standard_Package;
+
+   procedure Set_Time_Resolution (Resolution : Character)
+   is
+      Unit : Iir;
+      Prim : Iir;
+      Rng : Iir;
+   begin
+      case Resolution is
+         when 'f' =>
+            Prim := Time_Fs_Unit;
+         when 'p' =>
+            Prim := Time_Ps_Unit;
+         when 'n' =>
+            Prim := Time_Ns_Unit;
+         when 'u' =>
+            Prim := Time_Us_Unit;
+         when 'm' =>
+            Prim := Time_Ms_Unit;
+         when 's' =>
+            Prim := Time_Sec_Unit;
+         when 'M' =>
+            Prim := Time_Min_Unit;
+         when 'h' =>
+            Prim := Time_Hr_Unit;
+         when others =>
+            raise Internal_Error;
+      end case;
+
+      --  Adjust range of TIME subtype.
+      Rng := Get_Range_Constraint (Time_Subtype_Definition);
+      Set_Physical_Unit (Get_Left_Limit (Rng), Prim);
+      Set_Physical_Unit (Get_Right_Limit (Rng), Prim);
+
+      --  Adjust range of DELAY_LENGTH.
+      if Vhdl_Std >= Vhdl_93c then
+         Rng := Get_Range_Constraint (Delay_Length_Subtype_Definition);
+         Set_Physical_Unit (Get_Left_Limit (Rng), Prim);
+         Set_Physical_Unit (Get_Right_Limit (Rng), Prim);
+      end if;
+
+      Unit := Get_Unit_Chain (Time_Type_Definition);
+      while Unit /= Null_Iir loop
+         declare
+            Lit : constant Iir := Get_Physical_Literal (Unit);
+            Orig : constant Iir := Get_Literal_Origin (Lit);
+            Lit_Unit : Iir;
+         begin
+            if Prim = Null_Iir then
+               --  Primary already set, just recompute values.
+               Lit_Unit := Get_Physical_Literal (Get_Physical_Unit (Orig));
+               Set_Value (Lit, Get_Value (Orig) * Get_Value (Lit_Unit));
+            elsif Unit = Prim then
+               Set_Value (Lit, 1);
+               Prim := Null_Iir;
+            else
+               Set_Value (Lit, 0);
+            end if;
+         end;
+         Unit := Get_Chain (Unit);
+      end loop;
+   end Set_Time_Resolution;
+
+   function Get_Minimal_Time_Resolution return Character is
+   begin
+      if Get_Use_Flag (Time_Fs_Unit) then
+         return 'f';
+      end if;
+      if Get_Use_Flag (Time_Ps_Unit) then
+         return 'p';
+      end if;
+      if Get_Use_Flag (Time_Ns_Unit) then
+         return 'n';
+      end if;
+      if Get_Use_Flag (Time_Us_Unit) then
+         return 'u';
+      end if;
+      if Get_Use_Flag (Time_Ms_Unit) then
+         return 'm';
+      end if;
+      if Get_Use_Flag (Time_Sec_Unit) then
+         return 's';
+      end if;
+      if Get_Use_Flag (Time_Min_Unit) then
+         return 'M';
+      end if;
+      if Get_Use_Flag (Time_Hr_Unit) then
+         return 'h';
+      end if;
+      return '?';
+   end Get_Minimal_Time_Resolution;
 end Std_Package;
diff --git a/src/vhdl/std_package.ads b/src/vhdl/std_package.ads
index e655cb181..1c714b95c 100644
--- a/src/vhdl/std_package.ads
+++ b/src/vhdl/std_package.ads
@@ -27,10 +27,6 @@ package Std_Package is
    -- Some well know values declared in the STANDARD package.
    -- These values (except time_base) *must* not be modified, and are set by
    -- create_std_standard_package.
-   -- Time_base is the base unit of time.  It is set during the creation of
-   -- all these nodes, and can be modified only *immediatly* after.
-
-   Time_Base: Iir_Unit_Declaration := Null_Iir;
 
    Std_Standard_File: Iir_Design_File := Null_Iir;
    Std_Standard_Unit : Iir_Design_Unit := Null_Iir;
@@ -181,6 +177,10 @@ package Std_Package is
    --  Create the node for the standard package.
    procedure Create_Std_Standard_Package (Parent : Iir_Library_Declaration);
 
+   procedure Set_Time_Resolution (Resolution : Character);
+
+   --  Return the minimal time resolution according to use of time units.
+   function Get_Minimal_Time_Resolution return Character;
 private
    --  For speed reasons, some often used nodes are hard-coded.
    Error_Mark : constant Iir := 2;
diff --git a/src/vhdl/translate/ortho_front.adb b/src/vhdl/translate/ortho_front.adb
index 236c94906..143a6f6f1 100644
--- a/src/vhdl/translate/ortho_front.adb
+++ b/src/vhdl/translate/ortho_front.adb
@@ -393,6 +393,7 @@ package body Ortho_Front is
       Res : Iir_Design_File;
       Design : Iir_Design_Unit;
       Next_Design : Iir_Design_Unit;
+      Config : Iir;
    begin
       if Nbr_Parse = 0 then
          --  Initialize only once...
@@ -417,9 +418,13 @@ package body Ortho_Front is
                Error_Msg_Option ("missing -l for --elab");
                raise Option_Error;
             end if;
-            Translation.Elaborate
-              (Elab_Entity.all, Elab_Architecture.all,
-               Elab_Filelist.all, False);
+            Config := Configuration.Configure
+              (Elab_Entity.all, Elab_Architecture.all);
+            if Errorout.Nbr_Errors > 0 then
+               --  This may happen (bad entity for example).
+               raise Compilation_Error;
+            end if;
+            Translation.Elaborate (Config, Elab_Filelist.all, False);
 
             if Errorout.Nbr_Errors > 0 then
                --  This may happen (bad entity for example).
@@ -464,8 +469,9 @@ package body Ortho_Front is
 
             Flags.Flag_Elaborate := True;
             Flags.Flag_Only_Elab_Warnings := False;
-            Translation.Elaborate
-              (Elab_Entity.all, Elab_Architecture.all, "", True);
+            Config := Configuration.Configure
+              (Elab_Entity.all, Elab_Architecture.all);
+            Translation.Elaborate (Config, "", True);
 
             if Errorout.Nbr_Errors > 0 then
                --  This may happen (bad entity for example).
diff --git a/src/vhdl/translate/trans-chap12.adb b/src/vhdl/translate/trans-chap12.adb
index b0e096565..9a2d7022e 100644
--- a/src/vhdl/translate/trans-chap12.adb
+++ b/src/vhdl/translate/trans-chap12.adb
@@ -587,8 +587,7 @@ package body Trans.Chap12 is
       R := fclose (F);
    end Write_File_List;
 
-   procedure Elaborate (Primary : String;
-                        Secondary : String;
+   procedure Elaborate (Config : Iir_Design_Unit;
                         Filelist : String;
                         Whole : Boolean)
    is
@@ -596,17 +595,12 @@ package body Trans.Chap12 is
 
       Unit : Iir_Design_Unit;
       Lib_Unit : Iir;
-      Config : Iir_Design_Unit;
       Config_Lib : Iir_Configuration_Declaration;
       Entity : Iir_Entity_Declaration;
       Arch : Iir_Architecture_Body;
       Conf_Info : Config_Info_Acc;
       Last_Design_Unit : Natural;
    begin
-      Config := Configure (Primary, Secondary);
-      if Config = Null_Iir then
-         return;
-      end if;
       Config_Lib := Get_Library_Unit (Config);
       Entity := Get_Entity (Config_Lib);
       Arch := Strip_Denoting_Name
diff --git a/src/vhdl/translate/trans-chap12.ads b/src/vhdl/translate/trans-chap12.ads
index 23abea998..a0db62399 100644
--- a/src/vhdl/translate/trans-chap12.ads
+++ b/src/vhdl/translate/trans-chap12.ads
@@ -26,10 +26,8 @@ package Trans.Chap12 is
    --  Write to file FILELIST all the files that are needed to link the design.
    procedure Write_File_List (Filelist : String);
 
-   --  Primary unit + secondary unit (architecture name which may be null)
-   --  to elaborate.
-   procedure Elaborate (Primary : String;
-                        Secondary : String;
+   --  Generate elaboration code for CONFIG.
+   procedure Elaborate (Config : Iir_Design_Unit;
                         Filelist : String;
                         Whole : Boolean);
 end Trans.Chap12;
diff --git a/src/vhdl/translate/translation.adb b/src/vhdl/translate/translation.adb
index 5c39283e3..a7ec6e7da 100644
--- a/src/vhdl/translate/translation.adb
+++ b/src/vhdl/translate/translation.adb
@@ -2085,8 +2085,7 @@ package body Translation is
       Free_Old_Temp;
    end Finalize;
 
-   procedure Elaborate (Primary : String;
-                        Secondary : String;
+   procedure Elaborate (Config : Iir;
                         Filelist : String;
                         Whole : Boolean) renames Trans.Chap12.Elaborate;
 
diff --git a/src/vhdl/translate/translation.ads b/src/vhdl/translate/translation.ads
index 2228f8973..4c9b2ff27 100644
--- a/src/vhdl/translate/translation.ads
+++ b/src/vhdl/translate/translation.ads
@@ -40,10 +40,9 @@ package Translation is
 
    procedure Gen_Filename (Design_File : Iir);
 
-   --  Primary unit + secondary unit (architecture name which may be null)
-   --  to elaborate.
-   procedure Elaborate (Primary : String;
-                        Secondary : String;
+   --  Generate elaboration code for CONFIG.  Also use units from Configure
+   --  package.
+   procedure Elaborate (Config : Iir;
                         Filelist : String;
                         Whole : Boolean);