vhdl: recognize ieee.std_logic_1164.is_x.

6 files changed, 367 insertions, 353 deletions

diff --git a/python/libghdl/thin/std_names.py b/python/libghdl/thin/std_names.py
index 27639788f..3dca3b712 100644
--- a/python/libghdl/thin/std_names.py
+++ b/python/libghdl/thin/std_names.py
@@ -592,189 +592,190 @@ class Name:
     Rotate_Left = 806
     Rotate_Right = 807
     To_Bitvector = 808
-    Conv_Signed = 809
-    Conv_Unsigned = 810
-    Conv_Integer = 811
-    Math_Real = 812
-    Ceil = 813
-    Log2 = 814
-    Sin = 815
-    Cos = 816
-    Last_Ieee = 816
-    First_Synthesis = 817
-    Allconst = 817
-    Allseq = 818
-    Anyconst = 819
-    Anyseq = 820
-    Last_Synthesis = 820
-    First_Directive = 821
-    Define = 821
-    Endif = 822
-    Ifdef = 823
-    Ifndef = 824
-    Include = 825
-    Timescale = 826
-    Undef = 827
-    Protect = 828
-    Begin_Protected = 829
-    End_Protected = 830
-    Key_Block = 831
-    Data_Block = 832
-    Line = 833
-    Celldefine = 834
-    Endcelldefine = 835
-    Default_Nettype = 836
-    Resetall = 837
-    Last_Directive = 837
-    First_Systask = 838
-    Bits = 838
-    D_Root = 839
-    D_Unit = 840
-    Last_Systask = 840
-    First_SV_Method = 841
-    Size = 841
-    Insert = 842
-    Delete = 843
-    Pop_Front = 844
-    Pop_Back = 845
-    Push_Front = 846
-    Push_Back = 847
-    Name = 848
-    Len = 849
-    Substr = 850
-    Exists = 851
-    Atoi = 852
-    Itoa = 853
-    Find = 854
-    Find_Index = 855
-    Find_First = 856
-    Find_First_Index = 857
-    Find_Last = 858
-    Find_Last_Index = 859
-    Num = 860
-    Randomize = 861
-    Pre_Randomize = 862
-    Post_Randomize = 863
-    Srandom = 864
-    Get_Randstate = 865
-    Set_Randstate = 866
-    Seed = 867
-    State = 868
-    Last_SV_Method = 868
-    First_BSV = 869
-    uAction = 869
-    uActionValue = 870
-    BVI = 871
-    uC = 872
-    uCF = 873
-    uE = 874
-    uSB = 875
-    uSBR = 876
-    Action = 877
-    Endaction = 878
-    Actionvalue = 879
-    Endactionvalue = 880
-    Ancestor = 881
-    Clocked_By = 882
-    Default_Clock = 883
-    Default_Reset = 884
-    Dependencies = 885
-    Deriving = 886
-    Determines = 887
-    Enable = 888
-    Ifc_Inout = 889
-    Input_Clock = 890
-    Input_Reset = 891
-    Instance = 892
-    Endinstance = 893
-    Let = 894
-    Match = 895
-    Method = 896
-    Endmethod = 897
-    Numeric = 898
-    Output_Clock = 899
-    Output_Reset = 900
-    Par = 901
-    Endpar = 902
-    Path = 903
-    Provisos = 904
-    Ready = 905
-    Reset_By = 906
-    Rule = 907
-    Endrule = 908
-    Rules = 909
-    Endrules = 910
-    Same_Family = 911
-    Schedule = 912
-    Seq = 913
-    Endseq = 914
-    Typeclass = 915
-    Endtypeclass = 916
-    Valueof = 917
-    uValueof = 918
-    Last_BSV = 918
-    First_Comment = 919
-    Psl = 919
-    Pragma = 920
-    Synthesis = 921
-    Synopsys = 922
-    Translate_Off = 923
-    Translate_On = 924
-    Last_Comment = 924
-    First_PSL = 925
-    A = 925
-    Af = 926
-    Ag = 927
-    Ax = 928
-    Abort = 929
-    Assume_Guarantee = 930
-    Before = 931
-    Clock = 932
-    E = 933
-    Ef = 934
-    Eg = 935
-    Ex = 936
-    Endpoint = 937
-    Eventually = 938
-    Fairness = 939
-    Fell = 940
-    Forall = 941
-    G = 942
-    Inf = 943
-    Inherit = 944
-    Never = 945
-    Next_A = 946
-    Next_E = 947
-    Next_Event = 948
-    Next_Event_A = 949
-    Next_Event_E = 950
-    Prev = 951
-    Rose = 952
-    Strong = 953
-    W = 954
-    Whilenot = 955
-    Within = 956
-    X = 957
-    Last_PSL = 957
-    First_Edif = 958
-    Celltype = 968
-    View = 969
-    Viewtype = 970
-    Direction = 971
-    Contents = 972
-    Net = 973
-    Viewref = 974
-    Cellref = 975
-    Libraryref = 976
-    Portinstance = 977
-    Joined = 978
-    Portref = 979
-    Instanceref = 980
-    Design = 981
-    Designator = 982
-    Owner = 983
-    Member = 984
-    Number = 985
-    Rename = 986
-    Userdata = 987
-    Last_Edif = 987
+    Is_X = 809
+    Conv_Signed = 810
+    Conv_Unsigned = 811
+    Conv_Integer = 812
+    Math_Real = 813
+    Ceil = 814
+    Log2 = 815
+    Sin = 816
+    Cos = 817
+    Last_Ieee = 817
+    First_Synthesis = 818
+    Allconst = 818
+    Allseq = 819
+    Anyconst = 820
+    Anyseq = 821
+    Last_Synthesis = 821
+    First_Directive = 822
+    Define = 822
+    Endif = 823
+    Ifdef = 824
+    Ifndef = 825
+    Include = 826
+    Timescale = 827
+    Undef = 828
+    Protect = 829
+    Begin_Protected = 830
+    End_Protected = 831
+    Key_Block = 832
+    Data_Block = 833
+    Line = 834
+    Celldefine = 835
+    Endcelldefine = 836
+    Default_Nettype = 837
+    Resetall = 838
+    Last_Directive = 838
+    First_Systask = 839
+    Bits = 839
+    D_Root = 840
+    D_Unit = 841
+    Last_Systask = 841
+    First_SV_Method = 842
+    Size = 842
+    Insert = 843
+    Delete = 844
+    Pop_Front = 845
+    Pop_Back = 846
+    Push_Front = 847
+    Push_Back = 848
+    Name = 849
+    Len = 850
+    Substr = 851
+    Exists = 852
+    Atoi = 853
+    Itoa = 854
+    Find = 855
+    Find_Index = 856
+    Find_First = 857
+    Find_First_Index = 858
+    Find_Last = 859
+    Find_Last_Index = 860
+    Num = 861
+    Randomize = 862
+    Pre_Randomize = 863
+    Post_Randomize = 864
+    Srandom = 865
+    Get_Randstate = 866
+    Set_Randstate = 867
+    Seed = 868
+    State = 869
+    Last_SV_Method = 869
+    First_BSV = 870
+    uAction = 870
+    uActionValue = 871
+    BVI = 872
+    uC = 873
+    uCF = 874
+    uE = 875
+    uSB = 876
+    uSBR = 877
+    Action = 878
+    Endaction = 879
+    Actionvalue = 880
+    Endactionvalue = 881
+    Ancestor = 882
+    Clocked_By = 883
+    Default_Clock = 884
+    Default_Reset = 885
+    Dependencies = 886
+    Deriving = 887
+    Determines = 888
+    Enable = 889
+    Ifc_Inout = 890
+    Input_Clock = 891
+    Input_Reset = 892
+    Instance = 893
+    Endinstance = 894
+    Let = 895
+    Match = 896
+    Method = 897
+    Endmethod = 898
+    Numeric = 899
+    Output_Clock = 900
+    Output_Reset = 901
+    Par = 902
+    Endpar = 903
+    Path = 904
+    Provisos = 905
+    Ready = 906
+    Reset_By = 907
+    Rule = 908
+    Endrule = 909
+    Rules = 910
+    Endrules = 911
+    Same_Family = 912
+    Schedule = 913
+    Seq = 914
+    Endseq = 915
+    Typeclass = 916
+    Endtypeclass = 917
+    Valueof = 918
+    uValueof = 919
+    Last_BSV = 919
+    First_Comment = 920
+    Psl = 920
+    Pragma = 921
+    Synthesis = 922
+    Synopsys = 923
+    Translate_Off = 924
+    Translate_On = 925
+    Last_Comment = 925
+    First_PSL = 926
+    A = 926
+    Af = 927
+    Ag = 928
+    Ax = 929
+    Abort = 930
+    Assume_Guarantee = 931
+    Before = 932
+    Clock = 933
+    E = 934
+    Ef = 935
+    Eg = 936
+    Ex = 937
+    Endpoint = 938
+    Eventually = 939
+    Fairness = 940
+    Fell = 941
+    Forall = 942
+    G = 943
+    Inf = 944
+    Inherit = 945
+    Never = 946
+    Next_A = 947
+    Next_E = 948
+    Next_Event = 949
+    Next_Event_A = 950
+    Next_Event_E = 951
+    Prev = 952
+    Rose = 953
+    Strong = 954
+    W = 955
+    Whilenot = 956
+    Within = 957
+    X = 958
+    Last_PSL = 958
+    First_Edif = 959
+    Celltype = 969
+    View = 970
+    Viewtype = 971
+    Direction = 972
+    Contents = 973
+    Net = 974
+    Viewref = 975
+    Cellref = 976
+    Libraryref = 977
+    Portinstance = 978
+    Joined = 979
+    Portref = 980
+    Instanceref = 981
+    Design = 982
+    Designator = 983
+    Owner = 984
+    Member = 985
+    Number = 986
+    Rename = 987
+    Userdata = 988
+    Last_Edif = 988
diff --git a/python/libghdl/thin/vhdl/nodes.py b/python/libghdl/thin/vhdl/nodes.py
index 15b1d9074..e5c1a431b 100644
--- a/python/libghdl/thin/vhdl/nodes.py
+++ b/python/libghdl/thin/vhdl/nodes.py
@@ -1066,165 +1066,167 @@ class Iir_Predefined:
     Ieee_1164_Vector_Xnor = 187
     Ieee_1164_Vector_Not = 188
     Ieee_1164_To_Bitvector = 189
-    Ieee_1164_Rising_Edge = 190
-    Ieee_1164_Falling_Edge = 191
-    Ieee_1164_Vector_And_Reduce = 192
-    Ieee_1164_Vector_Or_Reduce = 193
-    Ieee_1164_Condition_Operator = 194
-    Ieee_Numeric_Std_Toint_Uns_Nat = 195
-    Ieee_Numeric_Std_Toint_Sgn_Int = 196
-    Ieee_Numeric_Std_Touns_Nat_Nat_Uns = 197
-    Ieee_Numeric_Std_Touns_Nat_Uns_Uns = 198
-    Ieee_Numeric_Std_Tosgn_Int_Nat_Sgn = 199
-    Ieee_Numeric_Std_Tosgn_Int_Sgn_Sgn = 200
-    Ieee_Numeric_Std_Resize_Uns_Nat = 201
-    Ieee_Numeric_Std_Resize_Sgn_Nat = 202
-    Ieee_Numeric_Std_Resize_Uns_Uns = 203
-    Ieee_Numeric_Std_Resize_Sgn_Sgn = 204
-    Ieee_Numeric_Std_Add_Uns_Uns = 205
-    Ieee_Numeric_Std_Add_Uns_Nat = 206
-    Ieee_Numeric_Std_Add_Nat_Uns = 207
-    Ieee_Numeric_Std_Add_Uns_Log = 208
-    Ieee_Numeric_Std_Add_Log_Uns = 209
-    Ieee_Numeric_Std_Add_Sgn_Sgn = 210
-    Ieee_Numeric_Std_Add_Sgn_Int = 211
-    Ieee_Numeric_Std_Add_Int_Sgn = 212
-    Ieee_Numeric_Std_Add_Sgn_Log = 213
-    Ieee_Numeric_Std_Add_Log_Sgn = 214
-    Ieee_Numeric_Std_Sub_Uns_Uns = 215
-    Ieee_Numeric_Std_Sub_Uns_Nat = 216
-    Ieee_Numeric_Std_Sub_Nat_Uns = 217
-    Ieee_Numeric_Std_Sub_Sgn_Sgn = 218
-    Ieee_Numeric_Std_Sub_Sgn_Int = 219
-    Ieee_Numeric_Std_Sub_Int_Sgn = 220
-    Ieee_Numeric_Std_Mul_Uns_Uns = 221
-    Ieee_Numeric_Std_Mul_Uns_Nat = 222
-    Ieee_Numeric_Std_Mul_Nat_Uns = 223
-    Ieee_Numeric_Std_Mul_Sgn_Sgn = 224
-    Ieee_Numeric_Std_Mul_Sgn_Int = 225
-    Ieee_Numeric_Std_Mul_Int_Sgn = 226
-    Ieee_Numeric_Std_Div_Uns_Uns = 227
-    Ieee_Numeric_Std_Div_Uns_Nat = 228
-    Ieee_Numeric_Std_Div_Nat_Uns = 229
-    Ieee_Numeric_Std_Div_Sgn_Sgn = 230
-    Ieee_Numeric_Std_Div_Sgn_Int = 231
-    Ieee_Numeric_Std_Div_Int_Sgn = 232
-    Ieee_Numeric_Std_Gt_Uns_Uns = 233
-    Ieee_Numeric_Std_Gt_Uns_Nat = 234
-    Ieee_Numeric_Std_Gt_Nat_Uns = 235
-    Ieee_Numeric_Std_Gt_Sgn_Sgn = 236
-    Ieee_Numeric_Std_Gt_Sgn_Int = 237
-    Ieee_Numeric_Std_Gt_Int_Sgn = 238
-    Ieee_Numeric_Std_Lt_Uns_Uns = 239
-    Ieee_Numeric_Std_Lt_Uns_Nat = 240
-    Ieee_Numeric_Std_Lt_Nat_Uns = 241
-    Ieee_Numeric_Std_Lt_Sgn_Sgn = 242
-    Ieee_Numeric_Std_Lt_Sgn_Int = 243
-    Ieee_Numeric_Std_Lt_Int_Sgn = 244
-    Ieee_Numeric_Std_Le_Uns_Uns = 245
-    Ieee_Numeric_Std_Le_Uns_Nat = 246
-    Ieee_Numeric_Std_Le_Nat_Uns = 247
-    Ieee_Numeric_Std_Le_Sgn_Sgn = 248
-    Ieee_Numeric_Std_Le_Sgn_Int = 249
-    Ieee_Numeric_Std_Le_Int_Sgn = 250
-    Ieee_Numeric_Std_Ge_Uns_Uns = 251
-    Ieee_Numeric_Std_Ge_Uns_Nat = 252
-    Ieee_Numeric_Std_Ge_Nat_Uns = 253
-    Ieee_Numeric_Std_Ge_Sgn_Sgn = 254
-    Ieee_Numeric_Std_Ge_Sgn_Int = 255
-    Ieee_Numeric_Std_Ge_Int_Sgn = 256
-    Ieee_Numeric_Std_Eq_Uns_Uns = 257
-    Ieee_Numeric_Std_Eq_Uns_Nat = 258
-    Ieee_Numeric_Std_Eq_Nat_Uns = 259
-    Ieee_Numeric_Std_Eq_Sgn_Sgn = 260
-    Ieee_Numeric_Std_Eq_Sgn_Int = 261
-    Ieee_Numeric_Std_Eq_Int_Sgn = 262
-    Ieee_Numeric_Std_Ne_Uns_Uns = 263
-    Ieee_Numeric_Std_Ne_Uns_Nat = 264
-    Ieee_Numeric_Std_Ne_Nat_Uns = 265
-    Ieee_Numeric_Std_Ne_Sgn_Sgn = 266
-    Ieee_Numeric_Std_Ne_Sgn_Int = 267
-    Ieee_Numeric_Std_Ne_Int_Sgn = 268
-    Ieee_Numeric_Std_Shl_Uns_Nat = 269
-    Ieee_Numeric_Std_Shr_Uns_Nat = 270
-    Ieee_Numeric_Std_Shl_Sgn_Nat = 271
-    Ieee_Numeric_Std_Shr_Sgn_Nat = 272
-    Ieee_Numeric_Std_Rol_Uns_Nat = 273
-    Ieee_Numeric_Std_Ror_Uns_Nat = 274
-    Ieee_Numeric_Std_Rol_Sgn_Nat = 275
-    Ieee_Numeric_Std_Ror_Sgn_Nat = 276
-    Ieee_Numeric_Std_Not_Uns = 277
-    Ieee_Numeric_Std_Not_Sgn = 278
-    Ieee_Numeric_Std_And_Uns_Uns = 279
-    Ieee_Numeric_Std_And_Sgn_Sgn = 280
-    Ieee_Numeric_Std_Or_Uns_Uns = 281
-    Ieee_Numeric_Std_Or_Sgn_Sgn = 282
-    Ieee_Numeric_Std_Nand_Uns_Uns = 283
-    Ieee_Numeric_Std_Nand_Sgn_Sgn = 284
-    Ieee_Numeric_Std_Nor_Uns_Uns = 285
-    Ieee_Numeric_Std_Nor_Sgn_Sgn = 286
-    Ieee_Numeric_Std_Xor_Uns_Uns = 287
-    Ieee_Numeric_Std_Xor_Sgn_Sgn = 288
-    Ieee_Numeric_Std_Xnor_Uns_Uns = 289
-    Ieee_Numeric_Std_Xnor_Sgn_Sgn = 290
-    Ieee_Numeric_Std_Neg_Uns = 291
-    Ieee_Numeric_Std_Neg_Sgn = 292
-    Ieee_Numeric_Std_Match_Log = 293
-    Ieee_Numeric_Std_Match_Uns = 294
-    Ieee_Numeric_Std_Match_Sgn = 295
-    Ieee_Numeric_Std_Match_Slv = 296
-    Ieee_Numeric_Std_Match_Suv = 297
-    Ieee_Math_Real_Ceil = 298
-    Ieee_Math_Real_Log2 = 299
-    Ieee_Math_Real_Sin = 300
-    Ieee_Math_Real_Cos = 301
-    Ieee_Std_Logic_Unsigned_Add_Slv_Slv = 302
-    Ieee_Std_Logic_Unsigned_Add_Slv_Int = 303
-    Ieee_Std_Logic_Unsigned_Add_Int_Slv = 304
-    Ieee_Std_Logic_Unsigned_Add_Slv_Sl = 305
-    Ieee_Std_Logic_Unsigned_Add_Sl_Slv = 306
-    Ieee_Std_Logic_Unsigned_Sub_Slv_Slv = 307
-    Ieee_Std_Logic_Unsigned_Sub_Slv_Int = 308
-    Ieee_Std_Logic_Unsigned_Sub_Int_Slv = 309
-    Ieee_Std_Logic_Unsigned_Sub_Slv_Sl = 310
-    Ieee_Std_Logic_Unsigned_Sub_Sl_Slv = 311
-    Ieee_Std_Logic_Unsigned_Lt_Slv_Slv = 312
-    Ieee_Std_Logic_Unsigned_Lt_Slv_Int = 313
-    Ieee_Std_Logic_Unsigned_Lt_Int_Slv = 314
-    Ieee_Std_Logic_Unsigned_Le_Slv_Slv = 315
-    Ieee_Std_Logic_Unsigned_Le_Slv_Int = 316
-    Ieee_Std_Logic_Unsigned_Le_Int_Slv = 317
-    Ieee_Std_Logic_Unsigned_Gt_Slv_Slv = 318
-    Ieee_Std_Logic_Unsigned_Gt_Slv_Int = 319
-    Ieee_Std_Logic_Unsigned_Gt_Int_Slv = 320
-    Ieee_Std_Logic_Unsigned_Ge_Slv_Slv = 321
-    Ieee_Std_Logic_Unsigned_Ge_Slv_Int = 322
-    Ieee_Std_Logic_Unsigned_Ge_Int_Slv = 323
-    Ieee_Std_Logic_Unsigned_Eq_Slv_Slv = 324
-    Ieee_Std_Logic_Unsigned_Eq_Slv_Int = 325
-    Ieee_Std_Logic_Unsigned_Eq_Int_Slv = 326
-    Ieee_Std_Logic_Unsigned_Ne_Slv_Slv = 327
-    Ieee_Std_Logic_Unsigned_Ne_Slv_Int = 328
-    Ieee_Std_Logic_Unsigned_Ne_Int_Slv = 329
-    Ieee_Std_Logic_Unsigned_Conv_Integer = 330
-    Ieee_Std_Logic_Signed_Add_Slv_Slv = 331
-    Ieee_Std_Logic_Signed_Add_Slv_Int = 332
-    Ieee_Std_Logic_Signed_Add_Int_Slv = 333
-    Ieee_Std_Logic_Signed_Add_Slv_Sl = 334
-    Ieee_Std_Logic_Signed_Add_Sl_Slv = 335
-    Ieee_Std_Logic_Signed_Sub_Slv_Slv = 336
-    Ieee_Std_Logic_Signed_Sub_Slv_Int = 337
-    Ieee_Std_Logic_Signed_Sub_Int_Slv = 338
-    Ieee_Std_Logic_Signed_Sub_Slv_Sl = 339
-    Ieee_Std_Logic_Signed_Sub_Sl_Slv = 340
-    Ieee_Std_Logic_Arith_Conv_Unsigned_Int = 341
-    Ieee_Std_Logic_Arith_Conv_Unsigned_Uns = 342
-    Ieee_Std_Logic_Arith_Conv_Unsigned_Sgn = 343
-    Ieee_Std_Logic_Arith_Conv_Unsigned_Log = 344
-    Ieee_Std_Logic_Arith_Conv_Integer_Int = 345
-    Ieee_Std_Logic_Arith_Conv_Integer_Uns = 346
-    Ieee_Std_Logic_Arith_Conv_Integer_Sgn = 347
-    Ieee_Std_Logic_Arith_Conv_Integer_Log = 348
+    Ieee_1164_Vector_Is_X = 190
+    Ieee_1164_Scalar_Is_X = 191
+    Ieee_1164_Rising_Edge = 192
+    Ieee_1164_Falling_Edge = 193
+    Ieee_1164_Vector_And_Reduce = 194
+    Ieee_1164_Vector_Or_Reduce = 195
+    Ieee_1164_Condition_Operator = 196
+    Ieee_Numeric_Std_Toint_Uns_Nat = 197
+    Ieee_Numeric_Std_Toint_Sgn_Int = 198
+    Ieee_Numeric_Std_Touns_Nat_Nat_Uns = 199
+    Ieee_Numeric_Std_Touns_Nat_Uns_Uns = 200
+    Ieee_Numeric_Std_Tosgn_Int_Nat_Sgn = 201
+    Ieee_Numeric_Std_Tosgn_Int_Sgn_Sgn = 202
+    Ieee_Numeric_Std_Resize_Uns_Nat = 203
+    Ieee_Numeric_Std_Resize_Sgn_Nat = 204
+    Ieee_Numeric_Std_Resize_Uns_Uns = 205
+    Ieee_Numeric_Std_Resize_Sgn_Sgn = 206
+    Ieee_Numeric_Std_Add_Uns_Uns = 207
+    Ieee_Numeric_Std_Add_Uns_Nat = 208
+    Ieee_Numeric_Std_Add_Nat_Uns = 209
+    Ieee_Numeric_Std_Add_Uns_Log = 210
+    Ieee_Numeric_Std_Add_Log_Uns = 211
+    Ieee_Numeric_Std_Add_Sgn_Sgn = 212
+    Ieee_Numeric_Std_Add_Sgn_Int = 213
+    Ieee_Numeric_Std_Add_Int_Sgn = 214
+    Ieee_Numeric_Std_Add_Sgn_Log = 215
+    Ieee_Numeric_Std_Add_Log_Sgn = 216
+    Ieee_Numeric_Std_Sub_Uns_Uns = 217
+    Ieee_Numeric_Std_Sub_Uns_Nat = 218
+    Ieee_Numeric_Std_Sub_Nat_Uns = 219
+    Ieee_Numeric_Std_Sub_Sgn_Sgn = 220
+    Ieee_Numeric_Std_Sub_Sgn_Int = 221
+    Ieee_Numeric_Std_Sub_Int_Sgn = 222
+    Ieee_Numeric_Std_Mul_Uns_Uns = 223
+    Ieee_Numeric_Std_Mul_Uns_Nat = 224
+    Ieee_Numeric_Std_Mul_Nat_Uns = 225
+    Ieee_Numeric_Std_Mul_Sgn_Sgn = 226
+    Ieee_Numeric_Std_Mul_Sgn_Int = 227
+    Ieee_Numeric_Std_Mul_Int_Sgn = 228
+    Ieee_Numeric_Std_Div_Uns_Uns = 229
+    Ieee_Numeric_Std_Div_Uns_Nat = 230
+    Ieee_Numeric_Std_Div_Nat_Uns = 231
+    Ieee_Numeric_Std_Div_Sgn_Sgn = 232
+    Ieee_Numeric_Std_Div_Sgn_Int = 233
+    Ieee_Numeric_Std_Div_Int_Sgn = 234
+    Ieee_Numeric_Std_Gt_Uns_Uns = 235
+    Ieee_Numeric_Std_Gt_Uns_Nat = 236
+    Ieee_Numeric_Std_Gt_Nat_Uns = 237
+    Ieee_Numeric_Std_Gt_Sgn_Sgn = 238
+    Ieee_Numeric_Std_Gt_Sgn_Int = 239
+    Ieee_Numeric_Std_Gt_Int_Sgn = 240
+    Ieee_Numeric_Std_Lt_Uns_Uns = 241
+    Ieee_Numeric_Std_Lt_Uns_Nat = 242
+    Ieee_Numeric_Std_Lt_Nat_Uns = 243
+    Ieee_Numeric_Std_Lt_Sgn_Sgn = 244
+    Ieee_Numeric_Std_Lt_Sgn_Int = 245
+    Ieee_Numeric_Std_Lt_Int_Sgn = 246
+    Ieee_Numeric_Std_Le_Uns_Uns = 247
+    Ieee_Numeric_Std_Le_Uns_Nat = 248
+    Ieee_Numeric_Std_Le_Nat_Uns = 249
+    Ieee_Numeric_Std_Le_Sgn_Sgn = 250
+    Ieee_Numeric_Std_Le_Sgn_Int = 251
+    Ieee_Numeric_Std_Le_Int_Sgn = 252
+    Ieee_Numeric_Std_Ge_Uns_Uns = 253
+    Ieee_Numeric_Std_Ge_Uns_Nat = 254
+    Ieee_Numeric_Std_Ge_Nat_Uns = 255
+    Ieee_Numeric_Std_Ge_Sgn_Sgn = 256
+    Ieee_Numeric_Std_Ge_Sgn_Int = 257
+    Ieee_Numeric_Std_Ge_Int_Sgn = 258
+    Ieee_Numeric_Std_Eq_Uns_Uns = 259
+    Ieee_Numeric_Std_Eq_Uns_Nat = 260
+    Ieee_Numeric_Std_Eq_Nat_Uns = 261
+    Ieee_Numeric_Std_Eq_Sgn_Sgn = 262
+    Ieee_Numeric_Std_Eq_Sgn_Int = 263
+    Ieee_Numeric_Std_Eq_Int_Sgn = 264
+    Ieee_Numeric_Std_Ne_Uns_Uns = 265
+    Ieee_Numeric_Std_Ne_Uns_Nat = 266
+    Ieee_Numeric_Std_Ne_Nat_Uns = 267
+    Ieee_Numeric_Std_Ne_Sgn_Sgn = 268
+    Ieee_Numeric_Std_Ne_Sgn_Int = 269
+    Ieee_Numeric_Std_Ne_Int_Sgn = 270
+    Ieee_Numeric_Std_Shl_Uns_Nat = 271
+    Ieee_Numeric_Std_Shr_Uns_Nat = 272
+    Ieee_Numeric_Std_Shl_Sgn_Nat = 273
+    Ieee_Numeric_Std_Shr_Sgn_Nat = 274
+    Ieee_Numeric_Std_Rol_Uns_Nat = 275
+    Ieee_Numeric_Std_Ror_Uns_Nat = 276
+    Ieee_Numeric_Std_Rol_Sgn_Nat = 277
+    Ieee_Numeric_Std_Ror_Sgn_Nat = 278
+    Ieee_Numeric_Std_Not_Uns = 279
+    Ieee_Numeric_Std_Not_Sgn = 280
+    Ieee_Numeric_Std_And_Uns_Uns = 281
+    Ieee_Numeric_Std_And_Sgn_Sgn = 282
+    Ieee_Numeric_Std_Or_Uns_Uns = 283
+    Ieee_Numeric_Std_Or_Sgn_Sgn = 284
+    Ieee_Numeric_Std_Nand_Uns_Uns = 285
+    Ieee_Numeric_Std_Nand_Sgn_Sgn = 286
+    Ieee_Numeric_Std_Nor_Uns_Uns = 287
+    Ieee_Numeric_Std_Nor_Sgn_Sgn = 288
+    Ieee_Numeric_Std_Xor_Uns_Uns = 289
+    Ieee_Numeric_Std_Xor_Sgn_Sgn = 290
+    Ieee_Numeric_Std_Xnor_Uns_Uns = 291
+    Ieee_Numeric_Std_Xnor_Sgn_Sgn = 292
+    Ieee_Numeric_Std_Neg_Uns = 293
+    Ieee_Numeric_Std_Neg_Sgn = 294
+    Ieee_Numeric_Std_Match_Log = 295
+    Ieee_Numeric_Std_Match_Uns = 296
+    Ieee_Numeric_Std_Match_Sgn = 297
+    Ieee_Numeric_Std_Match_Slv = 298
+    Ieee_Numeric_Std_Match_Suv = 299
+    Ieee_Math_Real_Ceil = 300
+    Ieee_Math_Real_Log2 = 301
+    Ieee_Math_Real_Sin = 302
+    Ieee_Math_Real_Cos = 303
+    Ieee_Std_Logic_Unsigned_Add_Slv_Slv = 304
+    Ieee_Std_Logic_Unsigned_Add_Slv_Int = 305
+    Ieee_Std_Logic_Unsigned_Add_Int_Slv = 306
+    Ieee_Std_Logic_Unsigned_Add_Slv_Sl = 307
+    Ieee_Std_Logic_Unsigned_Add_Sl_Slv = 308
+    Ieee_Std_Logic_Unsigned_Sub_Slv_Slv = 309
+    Ieee_Std_Logic_Unsigned_Sub_Slv_Int = 310
+    Ieee_Std_Logic_Unsigned_Sub_Int_Slv = 311
+    Ieee_Std_Logic_Unsigned_Sub_Slv_Sl = 312
+    Ieee_Std_Logic_Unsigned_Sub_Sl_Slv = 313
+    Ieee_Std_Logic_Unsigned_Lt_Slv_Slv = 314
+    Ieee_Std_Logic_Unsigned_Lt_Slv_Int = 315
+    Ieee_Std_Logic_Unsigned_Lt_Int_Slv = 316
+    Ieee_Std_Logic_Unsigned_Le_Slv_Slv = 317
+    Ieee_Std_Logic_Unsigned_Le_Slv_Int = 318
+    Ieee_Std_Logic_Unsigned_Le_Int_Slv = 319
+    Ieee_Std_Logic_Unsigned_Gt_Slv_Slv = 320
+    Ieee_Std_Logic_Unsigned_Gt_Slv_Int = 321
+    Ieee_Std_Logic_Unsigned_Gt_Int_Slv = 322
+    Ieee_Std_Logic_Unsigned_Ge_Slv_Slv = 323
+    Ieee_Std_Logic_Unsigned_Ge_Slv_Int = 324
+    Ieee_Std_Logic_Unsigned_Ge_Int_Slv = 325
+    Ieee_Std_Logic_Unsigned_Eq_Slv_Slv = 326
+    Ieee_Std_Logic_Unsigned_Eq_Slv_Int = 327
+    Ieee_Std_Logic_Unsigned_Eq_Int_Slv = 328
+    Ieee_Std_Logic_Unsigned_Ne_Slv_Slv = 329
+    Ieee_Std_Logic_Unsigned_Ne_Slv_Int = 330
+    Ieee_Std_Logic_Unsigned_Ne_Int_Slv = 331
+    Ieee_Std_Logic_Unsigned_Conv_Integer = 332
+    Ieee_Std_Logic_Signed_Add_Slv_Slv = 333
+    Ieee_Std_Logic_Signed_Add_Slv_Int = 334
+    Ieee_Std_Logic_Signed_Add_Int_Slv = 335
+    Ieee_Std_Logic_Signed_Add_Slv_Sl = 336
+    Ieee_Std_Logic_Signed_Add_Sl_Slv = 337
+    Ieee_Std_Logic_Signed_Sub_Slv_Slv = 338
+    Ieee_Std_Logic_Signed_Sub_Slv_Int = 339
+    Ieee_Std_Logic_Signed_Sub_Int_Slv = 340
+    Ieee_Std_Logic_Signed_Sub_Slv_Sl = 341
+    Ieee_Std_Logic_Signed_Sub_Sl_Slv = 342
+    Ieee_Std_Logic_Arith_Conv_Unsigned_Int = 343
+    Ieee_Std_Logic_Arith_Conv_Unsigned_Uns = 344
+    Ieee_Std_Logic_Arith_Conv_Unsigned_Sgn = 345
+    Ieee_Std_Logic_Arith_Conv_Unsigned_Log = 346
+    Ieee_Std_Logic_Arith_Conv_Integer_Int = 347
+    Ieee_Std_Logic_Arith_Conv_Integer_Uns = 348
+    Ieee_Std_Logic_Arith_Conv_Integer_Sgn = 349
+    Ieee_Std_Logic_Arith_Conv_Integer_Log = 350
 
 Get_Kind = libghdl.vhdl__nodes__get_kind
 Get_Location = libghdl.vhdl__nodes__get_location
diff --git a/src/std_names.adb b/src/std_names.adb
index 5612363d4..7f6e20242 100644
--- a/src/std_names.adb
+++ b/src/std_names.adb
@@ -644,6 +644,7 @@ package body Std_Names is
       Def ("rotate_left",        Name_Rotate_Left);
       Def ("rotate_right",       Name_Rotate_Right);
       Def ("to_bitvector",       Name_To_Bitvector);
+      Def ("is_x",               Name_Is_X);
       Def ("conv_signed",        Name_Conv_Signed);
       Def ("conv_unsigned",      Name_Conv_Unsigned);
       Def ("conv_integer",       Name_Conv_Integer);
diff --git a/src/std_names.ads b/src/std_names.ads
index 57901576b..544f7ed7b 100644
--- a/src/std_names.ads
+++ b/src/std_names.ads
@@ -725,14 +725,15 @@ package Std_Names is
    Name_Rotate_Left        : constant Name_Id := Name_First_Ieee + 026;
    Name_Rotate_Right       : constant Name_Id := Name_First_Ieee + 027;
    Name_To_Bitvector       : constant Name_Id := Name_First_Ieee + 028;
-   Name_Conv_Signed        : constant Name_Id := Name_First_Ieee + 029;
-   Name_Conv_Unsigned      : constant Name_Id := Name_First_Ieee + 030;
-   Name_Conv_Integer       : constant Name_Id := Name_First_Ieee + 031;
-   Name_Math_Real          : constant Name_Id := Name_First_Ieee + 032;
-   Name_Ceil               : constant Name_Id := Name_First_Ieee + 033;
-   Name_Log2               : constant Name_Id := Name_First_Ieee + 034;
-   Name_Sin                : constant Name_Id := Name_First_Ieee + 035;
-   Name_Cos                : constant Name_Id := Name_First_Ieee + 036;
+   Name_Is_X               : constant Name_Id := Name_First_Ieee + 029;
+   Name_Conv_Signed        : constant Name_Id := Name_First_Ieee + 030;
+   Name_Conv_Unsigned      : constant Name_Id := Name_First_Ieee + 031;
+   Name_Conv_Integer       : constant Name_Id := Name_First_Ieee + 032;
+   Name_Math_Real          : constant Name_Id := Name_First_Ieee + 033;
+   Name_Ceil               : constant Name_Id := Name_First_Ieee + 034;
+   Name_Log2               : constant Name_Id := Name_First_Ieee + 035;
+   Name_Sin                : constant Name_Id := Name_First_Ieee + 036;
+   Name_Cos                : constant Name_Id := Name_First_Ieee + 037;
    Name_Last_Ieee          : constant Name_Id := Name_Cos;
 
    Name_First_Synthesis    : constant Name_Id := Name_Last_Ieee + 1;
diff --git a/src/vhdl/vhdl-ieee-std_logic_1164.adb b/src/vhdl/vhdl-ieee-std_logic_1164.adb
index 431b5bf6a..9c123d16a 100644
--- a/src/vhdl/vhdl-ieee-std_logic_1164.adb
+++ b/src/vhdl/vhdl-ieee-std_logic_1164.adb
@@ -271,6 +271,9 @@ package body Vhdl.Ieee.Std_Logic_1164 is
                         when Name_Op_Condition =>
                            Predefined :=
                              Iir_Predefined_Ieee_1164_Condition_Operator;
+                        when Name_Is_X =>
+                           Predefined :=
+                             Iir_Predefined_Ieee_1164_Scalar_Is_X;
                         when others =>
                            Predefined := Iir_Predefined_None;
                      end case;
@@ -301,6 +304,9 @@ package body Vhdl.Ieee.Std_Logic_1164 is
                         when Name_Or =>
                            Predefined :=
                              Iir_Predefined_Ieee_1164_Vector_Or_Reduce;
+                        when Name_Is_X =>
+                           Predefined :=
+                             Iir_Predefined_Ieee_1164_Scalar_Is_X;
                         when others =>
                            Predefined := Iir_Predefined_None;
                      end case;
diff --git a/src/vhdl/vhdl-nodes.ads b/src/vhdl/vhdl-nodes.ads
index 1f65efb0f..688c30555 100644
--- a/src/vhdl/vhdl-nodes.ads
+++ b/src/vhdl/vhdl-nodes.ads
@@ -4920,6 +4920,9 @@ package Vhdl.Nodes is
 
       Iir_Predefined_Ieee_1164_To_Bitvector,
 
+      Iir_Predefined_Ieee_1164_Vector_Is_X,
+      Iir_Predefined_Ieee_1164_Scalar_Is_X,
+
       Iir_Predefined_Ieee_1164_Rising_Edge,
       Iir_Predefined_Ieee_1164_Falling_Edge,