aboutsummaryrefslogtreecommitdiffstats
path: root/src/synth/synth-decls.adb
blob: 89d3b3ad8b459770d637c5ffdfc05a43fb9b8559 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
--  Create declarations for synthesis.
--  Copyright (C) 2017 Tristan Gingold
--
--  This file is part of GHDL.
--
--  This program 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 of the License, or
--  (at your option) any later version.
--
--  This program 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 this program; if not, write to the Free Software
--  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
--  MA 02110-1301, USA.

with Types; use Types;
with Mutils; use Mutils;

with Netlists; use Netlists;
with Netlists.Builders; use Netlists.Builders;
with Netlists.Folds; use Netlists.Folds;
with Netlists.Utils; use Netlists.Utils;
with Netlists.Gates;

with Vhdl.Errors;
with Vhdl.Utils; use Vhdl.Utils;
with Vhdl.Std_Package;
with Vhdl.Ieee.Std_Logic_1164;

with Synth.Environment; use Synth.Environment;
with Synth.Expr; use Synth.Expr;
with Synth.Stmts;
with Synth.Source; use Synth.Source;
with Synth.Errors; use Synth.Errors;
with Synth.Files_Operations;
with Synth.Values; use Synth.Values;

package body Synth.Decls is
   procedure Synth_Anonymous_Subtype_Indication
     (Syn_Inst : Synth_Instance_Acc; Atype : Node);

   procedure Create_Var_Wire
     (Syn_Inst : Synth_Instance_Acc; Decl : Iir; Init : Valtyp)
   is
      Vt : constant Valtyp := Get_Value (Syn_Inst, Decl);
      Value : Net;
      Ival : Net;
      W : Width;
      Name : Sname;
   begin
      case Vt.Val.Kind is
         when Value_Wire =>
            --  FIXME: get the width directly from the wire ?
            W := Get_Type_Width (Vt.Typ);
            Name := New_Sname_User (Get_Identifier (Decl),
                                    Get_Sname (Syn_Inst));
            if Init /= No_Valtyp then
               Ival := Get_Net (Init);
               pragma Assert (Get_Width (Ival) = W);
               Value := Build_Isignal (Get_Build (Syn_Inst), Name, Ival);
            else
               Value := Build_Signal (Get_Build (Syn_Inst), Name, W);
            end if;
            Set_Location (Value, Decl);
            Set_Wire_Gate (Vt.Val.W, Value);
         when others =>
            raise Internal_Error;
      end case;
   end Create_Var_Wire;

   procedure Synth_Subtype_Indication_If_Anonymous
     (Syn_Inst : Synth_Instance_Acc; Atype : Node) is
   begin
      if Get_Type_Declarator (Atype) = Null_Node then
         Synth_Subtype_Indication (Syn_Inst, Atype);
      end if;
   end Synth_Subtype_Indication_If_Anonymous;

   function Synth_Array_Type_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node) return Type_Acc
   is
      El_Type : constant Node := Get_Element_Subtype (Def);
      Ndims : constant Natural := Get_Nbr_Dimensions (Def);
      El_Typ : Type_Acc;
      Typ : Type_Acc;
   begin
      Synth_Subtype_Indication_If_Anonymous (Syn_Inst, El_Type);
      El_Typ := Get_Subtype_Object (Syn_Inst, El_Type);

      if El_Typ.Kind in Type_Nets and then Ndims = 1 then
         Typ := Create_Unbounded_Vector (El_Typ);
      else
         Typ := Create_Unbounded_Array (Dim_Type (Ndims), El_Typ);
      end if;
      return Typ;
   end Synth_Array_Type_Definition;

   --  Synth subtype of record elements.
   procedure Synth_Record_Elements_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node)
   is
      El_List : constant Node_Flist := Get_Elements_Declaration_List (Def);
      El : Node;
   begin
      for I in Flist_First .. Flist_Last (El_List) loop
         El := Get_Nth_Element (El_List, I);
         Synth_Declaration_Type (Syn_Inst, El);
      end loop;
   end Synth_Record_Elements_Definition;

   function Synth_Record_Type_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node) return Type_Acc
   is
      El_List : constant Node_Flist := Get_Elements_Declaration_List (Def);
      Rec_Els : Rec_El_Array_Acc;
      El : Node;
      El_Typ : Type_Acc;
   begin
      if not Is_Fully_Constrained_Type (Def) then
         return null;
      end if;
      Rec_Els := Create_Rec_El_Array
        (Iir_Index32 (Get_Nbr_Elements (El_List)));

      for I in Flist_First .. Flist_Last (El_List) loop
         El := Get_Nth_Element (El_List, I);
         El_Typ := Get_Subtype_Object (Syn_Inst, Get_Type (El));
         Rec_Els.E (Iir_Index32 (I + 1)).Typ := El_Typ;
      end loop;

      return Create_Record_Type (Rec_Els);
   end Synth_Record_Type_Definition;

   function Synth_Access_Type_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node) return Type_Acc
   is
      Des_Type : constant Node := Get_Designated_Type (Def);
      Des_Typ : Type_Acc;
      Typ : Type_Acc;
   begin
      Synth_Subtype_Indication_If_Anonymous (Syn_Inst, Des_Type);
      Des_Typ := Get_Subtype_Object (Syn_Inst, Des_Type);

      Typ := Create_Access_Type (Des_Typ);
      return Typ;
   end Synth_Access_Type_Definition;

   function Synth_File_Type_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node) return Type_Acc
   is
      File_Type : constant Node := Get_Type (Get_File_Type_Mark (Def));
      File_Typ : Type_Acc;
      Typ : Type_Acc;
   begin
      File_Typ := Get_Subtype_Object (Syn_Inst, File_Type);

      Typ := Create_File_Type (File_Typ);
      return Typ;
   end Synth_File_Type_Definition;

   function Scalar_Size_To_Size (Def : Node) return Size_Type is
   begin
      case Get_Scalar_Size (Def) is
         when Scalar_8 =>
            return 1;
         when Scalar_16 =>
            return 2;
         when Scalar_32 =>
            return 4;
         when Scalar_64 =>
            return 8;
      end case;
   end Scalar_Size_To_Size;

   procedure Synth_Type_Definition (Syn_Inst : Synth_Instance_Acc; Def : Node)
   is
      Typ : Type_Acc;
   begin
      case Get_Kind (Def) is
         when Iir_Kind_Enumeration_Type_Definition =>
            if Def = Vhdl.Ieee.Std_Logic_1164.Std_Ulogic_Type
              or else Def = Vhdl.Ieee.Std_Logic_1164.Std_Logic_Type
            then
               Typ := Logic_Type;
            elsif Def = Vhdl.Std_Package.Boolean_Type_Definition then
               Typ := Boolean_Type;
            elsif Def = Vhdl.Std_Package.Bit_Type_Definition then
               Typ := Bit_Type;
            else
               declare
                  Nbr_El : constant Natural :=
                    Get_Nbr_Elements (Get_Enumeration_Literal_List (Def));
                  Rng : Discrete_Range_Type;
                  W : Width;
               begin
                  W := Uns32 (Clog2 (Uns64 (Nbr_El)));
                  Rng := (Dir => Iir_To,
                          Is_Signed => False,
                          Left => 0,
                          Right => Int64 (Nbr_El - 1));
                  Typ := Create_Discrete_Type
                    (Rng, Scalar_Size_To_Size (Def), W);
               end;
            end if;
         when Iir_Kind_Array_Type_Definition =>
            Typ := Synth_Array_Type_Definition (Syn_Inst, Def);
         when Iir_Kind_Access_Type_Definition =>
            Typ := Synth_Access_Type_Definition (Syn_Inst, Def);
         when Iir_Kind_File_Type_Definition =>
            Typ := Synth_File_Type_Definition (Syn_Inst, Def);
         when Iir_Kind_Record_Type_Definition =>
            Synth_Record_Elements_Definition (Syn_Inst, Def);
            Typ := Synth_Record_Type_Definition (Syn_Inst, Def);
         when others =>
            Vhdl.Errors.Error_Kind ("synth_type_definition", Def);
      end case;
      if Typ /= null then
         Create_Subtype_Object (Syn_Inst, Def, Typ);
      end if;
   end Synth_Type_Definition;

   procedure Synth_Anonymous_Type_Definition
     (Syn_Inst : Synth_Instance_Acc; Def : Node; St : Node)
   is
      Typ : Type_Acc;
   begin
      case Get_Kind (Def) is
         when Iir_Kind_Integer_Type_Definition
           | Iir_Kind_Physical_Type_Definition =>
            declare
               Cst : constant Node := Get_Range_Constraint (St);
               L, R : Int64;
               Rng : Discrete_Range_Type;
               W : Width;
            begin
               L := Get_Value (Get_Left_Limit (Cst));
               R := Get_Value (Get_Right_Limit (Cst));
               Rng := Synth_Discrete_Range_Expression
                 (L, R, Get_Direction (Cst));
               W := Discrete_Range_Width (Rng);
               Typ := Create_Discrete_Type
                 (Rng, Scalar_Size_To_Size (Def), W);
            end;
         when Iir_Kind_Floating_Type_Definition =>
            declare
               Cst : constant Node := Get_Range_Constraint (St);
               L, R : Fp64;
               Rng : Float_Range_Type;
            begin
               L := Get_Fp_Value (Get_Left_Limit (Cst));
               R := Get_Fp_Value (Get_Right_Limit (Cst));
               Rng := (Get_Direction (Cst), L, R);
               Typ := Create_Float_Type (Rng);
            end;
         when Iir_Kind_Array_Type_Definition =>
            Typ := Synth_Array_Type_Definition (Syn_Inst, Def);
         when others =>
            Vhdl.Errors.Error_Kind ("synth_anonymous_type_definition", Def);
      end case;
      Create_Subtype_Object (Syn_Inst, Def, Typ);
   end Synth_Anonymous_Type_Definition;

   function Synth_Discrete_Range_Constraint
     (Syn_Inst : Synth_Instance_Acc; Rng : Node) return Discrete_Range_Type
   is
      Res : Discrete_Range_Type;
   begin
      Synth_Discrete_Range (Syn_Inst, Rng, Res);
      return Res;
   end Synth_Discrete_Range_Constraint;

   function Synth_Float_Range_Constraint
     (Syn_Inst : Synth_Instance_Acc; Rng : Node) return Float_Range_Type is
   begin
      case Get_Kind (Rng) is
         when Iir_Kind_Range_Expression =>
            --  FIXME: check range.
            return Synth_Float_Range_Expression (Syn_Inst, Rng);
         when others =>
            Vhdl.Errors.Error_Kind ("synth_float_range_constraint", Rng);
      end case;
   end Synth_Float_Range_Constraint;

   function Synth_Array_Subtype_Indication
     (Syn_Inst : Synth_Instance_Acc; Atype : Node) return Type_Acc
   is
      El_Type : constant Node := Get_Element_Subtype (Atype);
      St_Indexes : constant Node_Flist := Get_Index_Subtype_List (Atype);
      Ptype : Node;
      St_El : Node;
      Btyp : Type_Acc;
      Etyp : Type_Acc;
      Bnds : Bound_Array_Acc;
   begin
      --  VHDL08
      if Get_Array_Element_Constraint (Atype) /= Null_Node
        or else
        (Get_Resolution_Indication (Atype) /= Null_Node
           and then
           (Get_Kind (Get_Resolution_Indication (Atype))
              = Iir_Kind_Array_Element_Resolution))
      then
         --  This subtype has created a new anonymous subtype for the
         --  element.
         Synth_Subtype_Indication (Syn_Inst, El_Type);
      end if;

      if not Get_Index_Constraint_Flag (Atype) then
         Ptype := Get_Type (Get_Subtype_Type_Mark (Atype));
         if Get_Element_Subtype (Ptype) = Get_Element_Subtype (Atype) then
            --  That's an alias.
            --  FIXME: maybe a resolution function was added?
            --  FIXME: also handle resolution added in element subtype.
            return Get_Subtype_Object (Syn_Inst, Ptype);
         end if;
      end if;

      Btyp := Get_Subtype_Object (Syn_Inst, Get_Base_Type (Atype));
      case Btyp.Kind is
         when Type_Unbounded_Vector =>
            if Get_Index_Constraint_Flag (Atype) then
               St_El := Get_Index_Type (St_Indexes, 0);
               return Create_Vector_Type
                 (Synth_Bounds_From_Range (Syn_Inst, St_El), Btyp.Uvec_El);
            else
               --  An alias.
               --  Handle vhdl08 definition of std_logic_vector from
               --  std_ulogic_vector.
               return Btyp;
            end if;
         when Type_Unbounded_Array =>
            --  FIXME: partially constrained arrays, subtype in indexes...
            Etyp := Get_Subtype_Object (Syn_Inst, El_Type);
            if Get_Index_Constraint_Flag (Atype) then
               Bnds := Create_Bound_Array
                 (Dim_Type (Get_Nbr_Elements (St_Indexes)));
               for I in Flist_First .. Flist_Last (St_Indexes) loop
                  St_El := Get_Index_Type (St_Indexes, I);
                  Bnds.D (Dim_Type (I + 1)) :=
                    Synth_Bounds_From_Range (Syn_Inst, St_El);
               end loop;
               return Create_Array_Type (Bnds, Etyp);
            else
               raise Internal_Error;
            end if;
         when others =>
            raise Internal_Error;
      end case;
   end Synth_Array_Subtype_Indication;

   function Synth_Subtype_Indication
     (Syn_Inst : Synth_Instance_Acc; Atype : Node) return Type_Acc is
   begin
      --  TODO: handle aliases directly.
      case Get_Kind (Atype) is
         when Iir_Kind_Array_Subtype_Definition =>
            return Synth_Array_Subtype_Indication (Syn_Inst, Atype);
         when Iir_Kind_Record_Subtype_Definition =>
            return Synth_Record_Type_Definition (Syn_Inst, Atype);
         when Iir_Kind_Integer_Subtype_Definition
           | Iir_Kind_Physical_Subtype_Definition
           | Iir_Kind_Enumeration_Subtype_Definition =>
            declare
               Btype : constant Type_Acc :=
                 Get_Subtype_Object (Syn_Inst, Get_Base_Type (Atype));
               Rng : Discrete_Range_Type;
               W : Width;
            begin
               if Btype.Kind in Type_Nets then
                  --  A subtype of a bit/logic type is still a bit/logic.
                  --  FIXME: bounds.
                  return Btype;
               else
                  Rng := Synth_Discrete_Range_Constraint
                    (Syn_Inst, Get_Range_Constraint (Atype));
                  W := Discrete_Range_Width (Rng);
                  return
                    Create_Discrete_Type (Rng, Btype.Sz, W);
               end if;
            end;
         when Iir_Kind_Floating_Subtype_Definition =>
            declare
               Rng : Float_Range_Type;
            begin
               Rng := Synth_Float_Range_Constraint
                 (Syn_Inst, Get_Range_Constraint (Atype));
               return Create_Float_Type (Rng);
            end;
         when others =>
            Vhdl.Errors.Error_Kind ("synth_subtype_indication", Atype);
      end case;
   end Synth_Subtype_Indication;

   procedure Synth_Subtype_Indication
     (Syn_Inst : Synth_Instance_Acc; Atype : Node)
   is
      Typ : Type_Acc;
   begin
      Typ := Synth_Subtype_Indication (Syn_Inst, Atype);
      Create_Subtype_Object (Syn_Inst, Atype, Typ);
   end Synth_Subtype_Indication;

   procedure Synth_Anonymous_Subtype_Indication
     (Syn_Inst : Synth_Instance_Acc; Atype : Node) is
   begin
      if Atype = Null_Node
        or else Get_Type_Declarator (Atype) /= Null_Node
      then
         return;
      end if;
      Synth_Subtype_Indication (Syn_Inst, Atype);
   end Synth_Anonymous_Subtype_Indication;

   pragma Unreferenced (Synth_Anonymous_Subtype_Indication);

   function Get_Declaration_Type (Decl : Node) return Node
   is
      Ind : constant Node := Get_Subtype_Indication (Decl);
      Atype : Node;
   begin
      if Ind = Null_Node then
         --  No subtype indication; use the same type.
         return Null_Node;
      end if;
      Atype := Ind;
      loop
         case Get_Kind (Atype) is
            when Iir_Kinds_Denoting_Name =>
               Atype := Get_Named_Entity (Atype);
            when Iir_Kind_Subtype_Declaration
              | Iir_Kind_Type_Declaration =>
               --  Type already declared, so already handled.
               return Null_Node;
            when Iir_Kind_Array_Subtype_Definition
              | Iir_Kind_Record_Subtype_Definition
              | Iir_Kind_Integer_Subtype_Definition
              | Iir_Kind_Floating_Subtype_Definition
              | Iir_Kind_Physical_Subtype_Definition
              | Iir_Kind_Enumeration_Subtype_Definition =>
               return Atype;
            when others =>
               Vhdl.Errors.Error_Kind ("get_declaration_type", Atype);
         end case;
      end loop;
   end Get_Declaration_Type;

   procedure Synth_Declaration_Type
     (Syn_Inst : Synth_Instance_Acc; Decl : Node)
   is
      Atype : constant Node := Get_Declaration_Type (Decl);
   begin
      if Atype = Null_Node then
         return;
      end if;
      Synth_Subtype_Indication (Syn_Inst, Atype);
   end Synth_Declaration_Type;

   procedure Synth_Constant_Declaration
     (Syn_Inst : Synth_Instance_Acc; Decl : Node; Last_Type : in out Node)
   is
      Deferred_Decl : constant Node := Get_Deferred_Declaration (Decl);
      First_Decl : Node;
      Decl_Type : Node;
      Val : Valtyp;
      Cst : Valtyp;
      Obj_Type : Type_Acc;
   begin
      Synth_Declaration_Type (Syn_Inst, Decl);
      if Deferred_Decl = Null_Node
        or else Get_Deferred_Declaration_Flag (Decl)
      then
         --  Create the object (except for full declaration of a
         --  deferred constant).
         Create_Object (Syn_Inst, Decl, No_Valtyp);
      end if;
      --  Initialize the value (except for a deferred declaration).
      if Deferred_Decl = Null_Node then
         --  A normal constant declaration
         First_Decl := Decl;
      elsif not Get_Deferred_Declaration_Flag (Decl) then
         --  The full declaration of a deferred constant.
         First_Decl := Deferred_Decl;
      else
         --  The first declaration of a deferred constant.
         First_Decl := Null_Node;
      end if;
      if First_Decl /= Null_Node then
         --  Use the type of the declaration.  The type of the constant may
         --  be derived from the value.
         --  FIXME: what about multiple declarations ?
         Decl_Type := Get_Subtype_Indication (Decl);
         if Decl_Type = Null_Node then
            Decl_Type := Last_Type;
         else
            if Get_Kind (Decl_Type) in Iir_Kinds_Denoting_Name then
               --  Type mark.
               Decl_Type := Get_Type (Get_Named_Entity (Decl_Type));
            end if;
            Last_Type := Decl_Type;
         end if;
         Obj_Type := Get_Subtype_Object (Syn_Inst, Decl_Type);
         Val := Synth_Expression_With_Type
           (Syn_Inst, Get_Default_Value (Decl), Obj_Type);
         if Val = No_Valtyp then
            Set_Error (Syn_Inst);
            return;
         end if;
         Val := Synth_Subtype_Conversion (Val, Obj_Type, True, Decl);
         --  For constant functions, the value must be constant.
         pragma Assert (not Get_Instance_Const (Syn_Inst)
                          or else Is_Static (Val.Val));
         case Val.Val.Kind is
            when Value_Const
              | Value_Alias =>
               Cst := Val;
            when others =>
               Cst := Create_Value_Const (Val, Decl);
         end case;
         Create_Object_Force (Syn_Inst, First_Decl, Cst);
      end if;
   end Synth_Constant_Declaration;

   procedure Synth_Attribute_Specification
     (Syn_Inst : Synth_Instance_Acc; Spec : Node)
   is
      Decl : constant Node := Get_Attribute_Designator (Spec);
      Value : Iir_Attribute_Value;
      Val : Valtyp;
      Val_Type : Type_Acc;
   begin
      Val_Type := Get_Subtype_Object
        (Syn_Inst, Get_Type (Get_Named_Entity (Decl)));
      Value := Get_Attribute_Value_Spec_Chain (Spec);
      while Value /= Null_Iir loop
         --  2. The expression is evaluated to determine the value
         --     of the attribute.
         --     It is an error if the value of the expression does not
         --     belong to the subtype of the attribute; if the
         --     attribute is of an array type, then an implicit
         --     subtype conversion is first performed on the value,
         --     unless the attribute's subtype indication denotes an
         --     unconstrained array type.
         Val := Synth_Expression_With_Type
           (Syn_Inst, Get_Expression (Spec), Val_Type);
         --  Check_Constraints (Instance, Val, Attr_Type, Decl);

         --  3. A new instance of the designated attribute is created
         --     and associated with each of the affected items.
         --
         --  4. Each new attribute instance is assigned the value of
         --     the expression.
         Create_Object (Syn_Inst, Value, Val);
         --  Unshare (Val, Instance_Pool);

         Value := Get_Spec_Chain (Value);
      end loop;
   end Synth_Attribute_Specification;

   procedure Synth_Subprogram_Declaration
     (Syn_Inst : Synth_Instance_Acc; Subprg : Node)
   is
      Inter : Node;
   begin
      if Is_Second_Subprogram_Specification (Subprg) then
         --  Already handled.
         return;
      end if;

      Inter := Get_Interface_Declaration_Chain (Subprg);
      while Inter /= Null_Node loop
         Synth_Declaration_Type (Syn_Inst, Inter);
         Inter := Get_Chain (Inter);
      end loop;
   end Synth_Subprogram_Declaration;

   procedure Synth_Convertible_Declarations (Syn_Inst : Synth_Instance_Acc)
   is
      use Vhdl.Std_Package;
   begin
      Create_Subtype_Object
        (Syn_Inst, Convertible_Integer_Type_Definition,
         Get_Subtype_Object (Syn_Inst, Universal_Integer_Type_Definition));
      Create_Subtype_Object
        (Syn_Inst, Convertible_Real_Type_Definition,
         Get_Subtype_Object (Syn_Inst, Universal_Real_Type_Definition));
   end Synth_Convertible_Declarations;

   function Create_Package_Instance (Parent_Inst : Synth_Instance_Acc;
                                     Pkg : Node)
                                    return Synth_Instance_Acc
   is
      Syn_Inst : Synth_Instance_Acc;
   begin
      Syn_Inst := Make_Instance (Parent_Inst, Pkg);
      if Get_Kind (Get_Parent (Pkg)) = Iir_Kind_Design_Unit then
         --  Global package.
         Create_Package_Object (Parent_Inst, Pkg, Syn_Inst, True);
      else
         --  Local package: check elaboration order.
         Create_Package_Object (Parent_Inst, Pkg, Syn_Inst, False);
      end if;
      return Syn_Inst;
   end Create_Package_Instance;

   procedure Synth_Package_Declaration
     (Parent_Inst : Synth_Instance_Acc; Pkg : Node)
   is
      Syn_Inst : Synth_Instance_Acc;
   begin
      if Is_Uninstantiated_Package (Pkg) then
         --  Nothing to do (yet) for uninstantiated packages.
         return;
      end if;

      Syn_Inst := Create_Package_Instance (Parent_Inst, Pkg);

      Synth_Declarations (Syn_Inst, Get_Declaration_Chain (Pkg));
      if Pkg = Vhdl.Std_Package.Standard_Package then
         Synth_Convertible_Declarations (Syn_Inst);
      end if;
   end Synth_Package_Declaration;

   procedure Synth_Package_Body
     (Parent_Inst : Synth_Instance_Acc; Pkg : Node; Bod : Node)
   is
      Pkg_Inst : Synth_Instance_Acc;
   begin
      if Is_Uninstantiated_Package (Pkg) then
         --  Nothing to do (yet) for uninstantiated packages.
         return;
      end if;

      Pkg_Inst := Get_Package_Object (Parent_Inst, Pkg);

      Synth_Declarations (Pkg_Inst, Get_Declaration_Chain (Bod));
   end Synth_Package_Body;

   procedure Synth_Generics_Association (Sub_Inst : Synth_Instance_Acc;
                                         Syn_Inst : Synth_Instance_Acc;
                                         Inter_Chain : Node;
                                         Assoc_Chain : Node)
   is
      Inter : Node;
      Inter_Type : Type_Acc;
      Assoc : Node;
      Assoc_Inter : Node;
      Actual : Node;
      Val : Valtyp;
   begin
      Assoc := Assoc_Chain;
      Assoc_Inter := Inter_Chain;
      while Is_Valid (Assoc) loop
         Inter := Get_Association_Interface (Assoc, Assoc_Inter);

         Synth_Declaration_Type (Sub_Inst, Inter);
         Inter_Type := Get_Subtype_Object (Sub_Inst, Get_Type (Inter));

         pragma Assert (Iir_Parameter_Modes (Get_Mode (Inter)) = Iir_In_Mode);
         case Get_Kind (Assoc) is
            when Iir_Kind_Association_Element_Open =>
               Actual := Get_Default_Value (Inter);
               Val := Synth_Expression_With_Type
                 (Sub_Inst, Actual, Inter_Type);
            when Iir_Kind_Association_Element_By_Expression =>
               Actual := Get_Actual (Assoc);
               Val := Synth_Expression_With_Type
                 (Syn_Inst, Actual, Inter_Type);
            when others =>
               raise Internal_Error;
         end case;

         Val := Synth_Subtype_Conversion (Val, Inter_Type, True, Assoc);

         pragma Assert (Is_Static (Val.Val));

         Create_Object (Sub_Inst, Inter, Val);

         Next_Association_Interface (Assoc, Assoc_Inter);
      end loop;
   end Synth_Generics_Association;

   procedure Synth_Package_Instantiation
     (Parent_Inst : Synth_Instance_Acc; Pkg : Node)
   is
      Bod : constant Node := Get_Instance_Package_Body (Pkg);
      Sub_Inst : Synth_Instance_Acc;
   begin
      Sub_Inst := Create_Package_Instance (Parent_Inst, Pkg);

      Synth_Generics_Association
        (Sub_Inst, Parent_Inst,
         Get_Generic_Chain (Pkg), Get_Generic_Map_Aspect_Chain (Pkg));

      Synth_Declarations (Sub_Inst, Get_Declaration_Chain (Pkg));

      if Bod /= Null_Node then
         --  Macro expended package instantiation.
         raise Internal_Error;
      else
         --  Shared body
         declare
            Uninst : constant Node := Get_Uninstantiated_Package_Decl (Pkg);
            Uninst_Bod : constant Node := Get_Package_Body (Uninst);
         begin
            Set_Uninstantiated_Scope (Sub_Inst, Uninst);
            --  Synth declarations of (optional) body.
            if Uninst_Bod /= Null_Node then
               Synth_Declarations
                 (Sub_Inst, Get_Declaration_Chain (Uninst_Bod));
            end if;
         end;
      end if;
   end Synth_Package_Instantiation;

   procedure Synth_Variable_Declaration
     (Syn_Inst : Synth_Instance_Acc; Decl : Node; Is_Subprg : Boolean)
   is
      Def : constant Iir := Get_Default_Value (Decl);
      --  Slot : constant Object_Slot_Type := Get_Info (Decl).Slot;
      Init : Valtyp;
      Obj_Typ : Type_Acc;
   begin
      Synth_Declaration_Type (Syn_Inst, Decl);
      Obj_Typ := Get_Subtype_Object (Syn_Inst, Get_Type (Decl));
      if not Obj_Typ.Is_Synth
        and then not Get_Instance_Const (Syn_Inst)
      then
         Error_Msg_Synth
           (+Decl, "variable with access type is not synthesizable");
         --  FIXME: use a poison value ?
         Create_Object (Syn_Inst, Decl, Create_Value_Default (Obj_Typ));
      else
         if Is_Valid (Def) then
            Init := Synth_Expression_With_Type (Syn_Inst, Def, Obj_Typ);
            Init := Synth_Subtype_Conversion (Init, Obj_Typ, False, Decl);
         else
            Init := Create_Value_Default (Obj_Typ);
         end if;
         if Get_Instance_Const (Syn_Inst) then
            Init := Unshare (Init, Current_Pool);
            Create_Object (Syn_Inst, Decl, Init);
         else
            Create_Wire_Object (Syn_Inst, Wire_Variable, Decl);
            Create_Var_Wire (Syn_Inst, Decl, Init);
            if Is_Subprg then
               Phi_Assign
                 (Get_Build (Syn_Inst),
                  Get_Value (Syn_Inst, Decl).Val.W, Get_Net (Init), 0);
            end if;
         end if;
      end if;
   end Synth_Variable_Declaration;

   procedure Synth_Object_Alias_Declaration
     (Syn_Inst : Synth_Instance_Acc; Decl : Node)
   is
      Atype : constant Node := Get_Declaration_Type (Decl);
      Off : Value_Offsets;
      Voff : Net;
      Rdwd : Width;
      Res : Valtyp;
      Obj_Typ : Type_Acc;
      Base : Valtyp;
      Typ : Type_Acc;
   begin
      --  Subtype indication may not be present.
      if Atype /= Null_Node then
         Synth_Subtype_Indication (Syn_Inst, Atype);
         Obj_Typ := Get_Subtype_Object (Syn_Inst, Atype);
      else
         Obj_Typ := null;
      end if;

      Stmts.Synth_Assignment_Prefix (Syn_Inst, Get_Name (Decl),
                                     Base, Typ, Off, Voff, Rdwd);
      pragma Assert (Voff = No_Net);
      if Base.Val.Kind = Value_Net then
         --  Object is a net if it is not writable.  Extract the
         --  bits for the alias.
         Res := Create_Value_Net
           (Build2_Extract (Get_Build (Syn_Inst),
                            Base.Val.N, Off.Net_Off, Typ.W),
            Typ);
      else
         Res := Create_Value_Alias (Base.Val, Off, Typ);
      end if;
      if Obj_Typ /= null then
         Res := Synth_Subtype_Conversion (Res, Obj_Typ, True, Decl);
      end if;
      Create_Object (Syn_Inst, Decl, Res);
   end Synth_Object_Alias_Declaration;

   procedure Synth_Declaration (Syn_Inst : Synth_Instance_Acc;
                                Decl : Node;
                                Is_Subprg : Boolean;
                                Last_Type : in out Node) is
   begin
      case Get_Kind (Decl) is
         when Iir_Kind_Variable_Declaration =>
            Synth_Variable_Declaration (Syn_Inst, Decl, Is_Subprg);
         when Iir_Kind_Interface_Variable_Declaration =>
            --  Ignore default value.
            Create_Wire_Object (Syn_Inst, Wire_Variable, Decl);
            Create_Var_Wire (Syn_Inst, Decl, No_Valtyp);
         when Iir_Kind_Constant_Declaration =>
            Synth_Constant_Declaration (Syn_Inst, Decl, Last_Type);
         when Iir_Kind_Signal_Declaration =>
            Synth_Declaration_Type (Syn_Inst, Decl);
            declare
               Def : constant Iir := Get_Default_Value (Decl);
               --  Slot : constant Object_Slot_Type := Get_Info (Decl).Slot;
               Init : Valtyp;
               Obj_Typ : Type_Acc;
            begin
               Create_Wire_Object (Syn_Inst, Wire_Signal, Decl);
               if Is_Valid (Def) then
                  Obj_Typ := Get_Subtype_Object (Syn_Inst, Get_Type (Decl));
                  Init := Synth_Expression_With_Type (Syn_Inst, Def, Obj_Typ);
                  Init := Synth_Subtype_Conversion
                    (Init, Obj_Typ, False, Decl);
               else
                  Init := No_Valtyp;
               end if;
               Create_Var_Wire (Syn_Inst, Decl, Init);
            end;
         when Iir_Kind_Object_Alias_Declaration =>
            Synth_Object_Alias_Declaration (Syn_Inst, Decl);
         when Iir_Kind_Anonymous_Signal_Declaration =>
            --  Anonymous signals created by inertial associations are
            --  simply ignored.
            null;
         when Iir_Kind_Procedure_Declaration
           | Iir_Kind_Function_Declaration =>
            Synth_Subprogram_Declaration (Syn_Inst, Decl);
         when Iir_Kind_Procedure_Body
           | Iir_Kind_Function_Body =>
            null;
         when Iir_Kind_Non_Object_Alias_Declaration =>
            null;
         when Iir_Kind_Attribute_Declaration =>
            --  Nothing to do: the type is a type_mark, not a subtype
            --  indication.
            null;
         when Iir_Kind_Attribute_Specification =>
            Synth_Attribute_Specification (Syn_Inst, Decl);
         when Iir_Kind_Type_Declaration =>
            Synth_Type_Definition (Syn_Inst, Get_Type_Definition (Decl));
         when Iir_Kind_Anonymous_Type_Declaration =>
            Synth_Anonymous_Type_Definition
              (Syn_Inst, Get_Type_Definition (Decl),
               Get_Subtype_Definition (Decl));
         when  Iir_Kind_Subtype_Declaration =>
            Synth_Declaration_Type (Syn_Inst, Decl);
         when Iir_Kind_Component_Declaration =>
            null;
         when Iir_Kind_File_Declaration =>
            declare
               F : File_Index;
               Res : Valtyp;
               Obj_Typ : Type_Acc;
            begin
               F := Synth.Files_Operations.Elaborate_File_Declaration
                 (Syn_Inst, Decl);
               Obj_Typ := Get_Subtype_Object (Syn_Inst, Get_Type (Decl));
               Res := Create_Value_File (Obj_Typ, F);
               Create_Object (Syn_Inst, Decl, Res);
            end;
         when Iir_Kind_Psl_Default_Clock =>
            --  Ignored; directly used by PSL directives.
            null;
         when Iir_Kind_Use_Clause =>
            null;
         when Iir_Kind_Configuration_Specification =>
            null;
         when others =>
            Vhdl.Errors.Error_Kind ("synth_declaration", Decl);
      end case;
   end Synth_Declaration;

   procedure Synth_Declarations
     (Syn_Inst : Synth_Instance_Acc; Decls : Iir; Is_Subprg : Boolean := False)
   is
      Decl : Node;
      Last_Type : Node;
   begin
      Last_Type := Null_Node;
      Decl := Decls;
      while Is_Valid (Decl) loop
         Synth_Declaration (Syn_Inst, Decl, Is_Subprg, Last_Type);

         exit when Is_Error (Syn_Inst);

         Decl := Get_Chain (Decl);
      end loop;
   end Synth_Declarations;

   procedure Finalize_Signal (Syn_Inst : Synth_Instance_Acc; Decl : Node)
   is
      use Netlists.Gates;
      Vt : Valtyp;
      Gate_Net : Net;
      Gate : Instance;
      Drv : Net;
      Def_Val : Net;
   begin
      Vt := Get_Value (Syn_Inst, Decl);
      if Vt = No_Valtyp then
         pragma Assert (Is_Error (Syn_Inst));
         return;
      end if;

      Gate_Net := Get_Wire_Gate (Vt.Val.W);
      Gate := Get_Net_Parent (Gate_Net);
      case Get_Id (Gate) is
         when Id_Signal =>
            Drv := Get_Input_Net (Gate, 0);
            Def_Val := No_Net;
         when Id_Isignal =>
            Drv := Get_Input_Net (Gate, 0);
            Def_Val := Get_Input_Net (Gate, 1);
         when others =>
            --  Todo: output ?
            raise Internal_Error;
      end case;
      if Drv = No_Net then
         if Is_Connected (Get_Output (Gate, 0)) then
            --  No warning if the signal is not used.
            --  TODO: maybe simply remove it.
            if Def_Val = No_Net then
               Warning_Msg_Synth
                 (+Decl, "%n is never assigned and has no default value",
                  (1 => +Decl));
            else
               Warning_Msg_Synth (+Decl, "%n is never assigned", (1 => +Decl));
            end if;
         end if;
         if Def_Val = No_Net then
            Def_Val := Build_Const_X (Get_Build (Syn_Inst),
                                      Get_Width (Gate_Net));
         end if;
         Connect (Get_Input (Gate, 0), Def_Val);
      end if;

      Free_Wire (Vt.Val.W);
   end Finalize_Signal;

   procedure Finalize_Declaration
     (Syn_Inst : Synth_Instance_Acc; Decl : Node; Is_Subprg : Boolean) is
   begin
      case Get_Kind (Decl) is
         when Iir_Kind_Variable_Declaration
           | Iir_Kind_Interface_Variable_Declaration =>
            if not Get_Instance_Const (Syn_Inst) then
               declare
                  Vt : constant Valtyp := Get_Value (Syn_Inst, Decl);
               begin
                  Free_Wire (Vt.Val.W);
               end;
            end if;
         when Iir_Kind_Constant_Declaration =>
            null;
         when Iir_Kind_Signal_Declaration =>
            pragma Assert (not Is_Subprg);
            Finalize_Signal (Syn_Inst, Decl);
         when Iir_Kind_Anonymous_Signal_Declaration =>
            null;
         when Iir_Kind_Object_Alias_Declaration =>
            null;
         when Iir_Kind_Procedure_Declaration
           | Iir_Kind_Function_Declaration =>
            null;
         when Iir_Kind_Procedure_Body
           | Iir_Kind_Function_Body =>
            null;
         when Iir_Kind_Non_Object_Alias_Declaration =>
            null;
         when Iir_Kind_Attribute_Declaration =>
            null;
         when Iir_Kind_Attribute_Specification =>
            null;
         when Iir_Kind_Type_Declaration =>
            null;
         when Iir_Kind_Anonymous_Type_Declaration =>
            null;
         when  Iir_Kind_Subtype_Declaration =>
            null;
         when Iir_Kind_Component_Declaration =>
            null;
         when Iir_Kind_File_Declaration =>
            null;
         when Iir_Kind_Configuration_Specification =>
            null;
         when Iir_Kind_Psl_Default_Clock =>
            --  Ignored; directly used by PSL directives.
            null;
         when others =>
            Vhdl.Errors.Error_Kind ("finalize_declaration", Decl);
      end case;
   end Finalize_Declaration;

   procedure Finalize_Declarations (Syn_Inst : Synth_Instance_Acc;
                                    Decls : Iir;
                                    Is_Subprg : Boolean := False)
   is
      Decl : Iir;
   begin
      Decl := Decls;
      while Is_Valid (Decl) loop
         Finalize_Declaration (Syn_Inst, Decl, Is_Subprg);

         Decl := Get_Chain (Decl);
      end loop;
   end Finalize_Declarations;
end Synth.Decls;