Add suspend_flag.

6 files changed, 316 insertions, 174 deletions

diff --git a/src/vhdl/iirs.adb b/src/vhdl/iirs.adb
index ac25a832c..1e57b035c 100644
--- a/src/vhdl/iirs.adb
+++ b/src/vhdl/iirs.adb
@@ -5139,6 +5139,22 @@ package body Iirs is
       Set_Flag11 (Decl, Flag);
    end Set_Has_Class;
 
+   function Get_Suspend_Flag (Stmt : Iir) return Boolean is
+   begin
+      pragma Assert (Stmt /= Null_Iir);
+      pragma Assert (Has_Suspend_Flag (Get_Kind (Stmt)),
+                     "no field Suspend_Flag");
+      return Get_Flag11 (Stmt);
+   end Get_Suspend_Flag;
+
+   procedure Set_Suspend_Flag (Stmt : Iir; Flag : Boolean) is
+   begin
+      pragma Assert (Stmt /= Null_Iir);
+      pragma Assert (Has_Suspend_Flag (Get_Kind (Stmt)),
+                     "no field Suspend_Flag");
+      Set_Flag11 (Stmt, Flag);
+   end Set_Suspend_Flag;
+
    function Get_Is_Ref (N : Iir) return Boolean is
    begin
       pragma Assert (N /= Null_Iir);
diff --git a/src/vhdl/iirs.ads b/src/vhdl/iirs.ads
index 0db83caec..37327913c 100644
--- a/src/vhdl/iirs.ads
+++ b/src/vhdl/iirs.ads
@@ -1271,6 +1271,9 @@ package Iirs is
    --  True is the specification is immediately followed by a body.
    --   Get/Set_Has_Body (Flag9)
    --
+   -- Only for Iir_Kind_Procedure_Declaration:
+   --   Get/Set_Suspend_Flag (Flag11)
+   --
    --   Get/Set_Wait_State (State1)
    --
    -- Only for Iir_Kind_Procedure_Declaration:
@@ -1314,6 +1317,9 @@ package Iirs is
    --   Get/Set_End_Has_Reserved_Id (Flag8)
    --
    --   Get/Set_End_Has_Identifier (Flag9)
+   --
+   -- Only for Iir_Kind_Procedure_Body:
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_Signal_Declaration (Short)
    --
@@ -2418,6 +2424,9 @@ package Iirs is
    --   Get/Set_End_Has_Identifier (Flag9)
    --
    --   Get/Set_End_Has_Postponed (Flag10)
+   --
+   -- Only for Iir_Kind_Process_Statement:
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_Concurrent_Assertion_Statement (Short)
    --
@@ -2689,6 +2698,9 @@ package Iirs is
    --   Get/Set_Visible_Flag (Flag4)
    --
    --   Get/Set_End_Has_Identifier (Flag9)
+   --
+   -- Only for Iir_Kind_If_Statement:
+   --   Get/Set_Suspend_Flag (Flag11)
 
    --  LRM08 10.10 Loop statement / LRM93 8.9
    --
@@ -2724,6 +2736,8 @@ package Iirs is
    --   Get/Set_Is_Within_Flag (Flag5)
    --
    --   Get/Set_End_Has_Identifier (Flag9)
+   --
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_While_Loop_Statement (Short)
    --
@@ -2741,6 +2755,8 @@ package Iirs is
    --   Get/Set_Visible_Flag (Flag4)
    --
    --   Get/Set_End_Has_Identifier (Flag9)
+   --
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_Exit_Statement (Short)
    -- Iir_Kind_Next_Statement (Short)
@@ -2892,6 +2908,8 @@ package Iirs is
    --   Get/Set_Visible_Flag (Flag4)
    --
    --   Get/Set_End_Has_Identifier (Flag9)
+   --
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_Procedure_Call_Statement (Short)
    -- Iir_Kind_Concurrent_Procedure_Call_Statement (Short)
@@ -2909,6 +2927,8 @@ package Iirs is
    --   Get/Set_Postponed_Flag (Flag3)
    --
    --   Get/Set_Visible_Flag (Flag4)
+   --
+   --   Get/Set_Suspend_Flag (Flag11)
 
    -- Iir_Kind_Procedure_Call (Short)
    --
@@ -6496,6 +6516,15 @@ package Iirs is
    function Get_Has_Class (Decl : Iir) return Boolean;
    procedure Set_Has_Class (Decl : Iir; Flag : Boolean);
 
+   --  Set on wait, procedure call and composite statements when there is a
+   --  sub-statement that can suspend a procedure or a process.  Also set
+   --  on procedure declaration.  Note that the flag is conservative: it must
+   --  be true if the node contains directly or indirectly a wait statement,
+   --  but need not to be false otherwise.
+   --  Field: Flag11
+   function Get_Suspend_Flag (Stmt : Iir) return Boolean;
+   procedure Set_Suspend_Flag (Stmt : Iir; Flag : Boolean);
+
    --  Set to True if Maybe_Ref fields are references.  This cannot be shared
    --  with Has_Identifier_List as: Is_Ref is set to True on all items but
    --  the first, while Has_Identifier_List is set to True on all items but
diff --git a/src/vhdl/nodes_meta.adb b/src/vhdl/nodes_meta.adb
index c93582571..c10ad3382 100644
--- a/src/vhdl/nodes_meta.adb
+++ b/src/vhdl/nodes_meta.adb
@@ -307,6 +307,7 @@ package body Nodes_Meta is
       Field_Has_Identifier_List => Type_Boolean,
       Field_Has_Mode => Type_Boolean,
       Field_Has_Class => Type_Boolean,
+      Field_Suspend_Flag => Type_Boolean,
       Field_Is_Ref => Type_Boolean,
       Field_Psl_Property => Type_PSL_Node,
       Field_Psl_Declaration => Type_PSL_Node,
@@ -900,6 +901,8 @@ package body Nodes_Meta is
             return "has_mode";
          when Field_Has_Class =>
             return "has_class";
+         when Field_Suspend_Flag =>
+            return "suspend_flag";
          when Field_Is_Ref =>
             return "is_ref";
          when Field_Psl_Property =>
@@ -2000,6 +2003,8 @@ package body Nodes_Meta is
             return Attr_None;
          when Field_Has_Class =>
             return Attr_None;
+         when Field_Suspend_Flag =>
+            return Attr_None;
          when Field_Is_Ref =>
             return Attr_None;
          when Field_Psl_Property =>
@@ -2761,6 +2766,7 @@ package body Nodes_Meta is
       Field_Subprogram_Hash,
       Field_Implicit_Definition,
       Field_Seen_Flag,
+      Field_Suspend_Flag,
       Field_Passive_Flag,
       Field_Foreign_Flag,
       Field_Visible_Flag,
@@ -2790,6 +2796,7 @@ package body Nodes_Meta is
       Field_Callees_List,
       --  Iir_Kind_Procedure_Body
       Field_Impure_Depth,
+      Field_Suspend_Flag,
       Field_End_Has_Reserved_Id,
       Field_End_Has_Identifier,
       Field_Declaration_Chain,
@@ -3335,6 +3342,7 @@ package body Nodes_Meta is
       Field_Label,
       Field_Seen_Flag,
       Field_End_Has_Postponed,
+      Field_Suspend_Flag,
       Field_Passive_Flag,
       Field_Postponed_Flag,
       Field_Visible_Flag,
@@ -3412,6 +3420,7 @@ package body Nodes_Meta is
       Field_Parent,
       --  Iir_Kind_Concurrent_Procedure_Call_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Postponed_Flag,
       Field_Visible_Flag,
       Field_Procedure_Call,
@@ -3543,6 +3552,7 @@ package body Nodes_Meta is
       Field_Type,
       --  Iir_Kind_For_Loop_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Visible_Flag,
       Field_Is_Within_Flag,
       Field_End_Has_Identifier,
@@ -3552,6 +3562,7 @@ package body Nodes_Meta is
       Field_Parent,
       --  Iir_Kind_While_Loop_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Visible_Flag,
       Field_End_Has_Identifier,
       Field_Condition,
@@ -3574,6 +3585,7 @@ package body Nodes_Meta is
       Field_Parent,
       --  Iir_Kind_Case_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Visible_Flag,
       Field_End_Has_Identifier,
       Field_Case_Statement_Alternative_Chain,
@@ -3582,12 +3594,14 @@ package body Nodes_Meta is
       Field_Parent,
       --  Iir_Kind_Procedure_Call_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Visible_Flag,
       Field_Procedure_Call,
       Field_Chain,
       Field_Parent,
       --  Iir_Kind_If_Statement
       Field_Label,
+      Field_Suspend_Flag,
       Field_Visible_Flag,
       Field_End_Has_Identifier,
       Field_Condition,
@@ -4040,160 +4054,160 @@ package body Nodes_Meta is
       Iir_Kind_Through_Quantity_Declaration => 604,
       Iir_Kind_Enumeration_Literal => 615,
       Iir_Kind_Function_Declaration => 639,
-      Iir_Kind_Procedure_Declaration => 661,
-      Iir_Kind_Function_Body => 671,
-      Iir_Kind_Procedure_Body => 681,
-      Iir_Kind_Object_Alias_Declaration => 693,
-      Iir_Kind_File_Declaration => 708,
-      Iir_Kind_Guard_Signal_Declaration => 721,
-      Iir_Kind_Signal_Declaration => 738,
-      Iir_Kind_Variable_Declaration => 751,
-      Iir_Kind_Constant_Declaration => 765,
-      Iir_Kind_Iterator_Declaration => 777,
-      Iir_Kind_Interface_Constant_Declaration => 793,
-      Iir_Kind_Interface_Variable_Declaration => 809,
-      Iir_Kind_Interface_Signal_Declaration => 830,
-      Iir_Kind_Interface_File_Declaration => 846,
-      Iir_Kind_Interface_Package_Declaration => 855,
-      Iir_Kind_Identity_Operator => 859,
-      Iir_Kind_Negation_Operator => 863,
-      Iir_Kind_Absolute_Operator => 867,
-      Iir_Kind_Not_Operator => 871,
-      Iir_Kind_Condition_Operator => 875,
-      Iir_Kind_Reduction_And_Operator => 879,
-      Iir_Kind_Reduction_Or_Operator => 883,
-      Iir_Kind_Reduction_Nand_Operator => 887,
-      Iir_Kind_Reduction_Nor_Operator => 891,
-      Iir_Kind_Reduction_Xor_Operator => 895,
-      Iir_Kind_Reduction_Xnor_Operator => 899,
-      Iir_Kind_And_Operator => 904,
-      Iir_Kind_Or_Operator => 909,
-      Iir_Kind_Nand_Operator => 914,
-      Iir_Kind_Nor_Operator => 919,
-      Iir_Kind_Xor_Operator => 924,
-      Iir_Kind_Xnor_Operator => 929,
-      Iir_Kind_Equality_Operator => 934,
-      Iir_Kind_Inequality_Operator => 939,
-      Iir_Kind_Less_Than_Operator => 944,
-      Iir_Kind_Less_Than_Or_Equal_Operator => 949,
-      Iir_Kind_Greater_Than_Operator => 954,
-      Iir_Kind_Greater_Than_Or_Equal_Operator => 959,
-      Iir_Kind_Match_Equality_Operator => 964,
-      Iir_Kind_Match_Inequality_Operator => 969,
-      Iir_Kind_Match_Less_Than_Operator => 974,
-      Iir_Kind_Match_Less_Than_Or_Equal_Operator => 979,
-      Iir_Kind_Match_Greater_Than_Operator => 984,
-      Iir_Kind_Match_Greater_Than_Or_Equal_Operator => 989,
-      Iir_Kind_Sll_Operator => 994,
-      Iir_Kind_Sla_Operator => 999,
-      Iir_Kind_Srl_Operator => 1004,
-      Iir_Kind_Sra_Operator => 1009,
-      Iir_Kind_Rol_Operator => 1014,
-      Iir_Kind_Ror_Operator => 1019,
-      Iir_Kind_Addition_Operator => 1024,
-      Iir_Kind_Substraction_Operator => 1029,
-      Iir_Kind_Concatenation_Operator => 1034,
-      Iir_Kind_Multiplication_Operator => 1039,
-      Iir_Kind_Division_Operator => 1044,
-      Iir_Kind_Modulus_Operator => 1049,
-      Iir_Kind_Remainder_Operator => 1054,
-      Iir_Kind_Exponentiation_Operator => 1059,
-      Iir_Kind_Function_Call => 1067,
-      Iir_Kind_Aggregate => 1073,
-      Iir_Kind_Parenthesis_Expression => 1076,
-      Iir_Kind_Qualified_Expression => 1080,
-      Iir_Kind_Type_Conversion => 1085,
-      Iir_Kind_Allocator_By_Expression => 1089,
-      Iir_Kind_Allocator_By_Subtype => 1093,
-      Iir_Kind_Selected_Element => 1099,
-      Iir_Kind_Dereference => 1104,
-      Iir_Kind_Implicit_Dereference => 1109,
-      Iir_Kind_Slice_Name => 1116,
-      Iir_Kind_Indexed_Name => 1122,
-      Iir_Kind_Psl_Expression => 1124,
-      Iir_Kind_Sensitized_Process_Statement => 1144,
-      Iir_Kind_Process_Statement => 1163,
-      Iir_Kind_Concurrent_Conditional_Signal_Assignment => 1174,
-      Iir_Kind_Concurrent_Selected_Signal_Assignment => 1186,
-      Iir_Kind_Concurrent_Assertion_Statement => 1194,
-      Iir_Kind_Psl_Default_Clock => 1198,
-      Iir_Kind_Psl_Assert_Statement => 1207,
-      Iir_Kind_Psl_Cover_Statement => 1216,
-      Iir_Kind_Concurrent_Procedure_Call_Statement => 1222,
-      Iir_Kind_Block_Statement => 1235,
-      Iir_Kind_If_Generate_Statement => 1245,
-      Iir_Kind_For_Generate_Statement => 1254,
-      Iir_Kind_Component_Instantiation_Statement => 1264,
-      Iir_Kind_Simple_Simultaneous_Statement => 1271,
-      Iir_Kind_Generate_Statement_Body => 1282,
-      Iir_Kind_If_Generate_Else_Clause => 1287,
-      Iir_Kind_Signal_Assignment_Statement => 1296,
-      Iir_Kind_Null_Statement => 1300,
-      Iir_Kind_Assertion_Statement => 1307,
-      Iir_Kind_Report_Statement => 1313,
-      Iir_Kind_Wait_Statement => 1320,
-      Iir_Kind_Variable_Assignment_Statement => 1326,
-      Iir_Kind_Return_Statement => 1332,
-      Iir_Kind_For_Loop_Statement => 1340,
-      Iir_Kind_While_Loop_Statement => 1347,
-      Iir_Kind_Next_Statement => 1353,
-      Iir_Kind_Exit_Statement => 1359,
-      Iir_Kind_Case_Statement => 1366,
-      Iir_Kind_Procedure_Call_Statement => 1371,
-      Iir_Kind_If_Statement => 1379,
-      Iir_Kind_Elsif => 1384,
-      Iir_Kind_Character_Literal => 1391,
-      Iir_Kind_Simple_Name => 1398,
-      Iir_Kind_Selected_Name => 1406,
-      Iir_Kind_Operator_Symbol => 1411,
-      Iir_Kind_Selected_By_All_Name => 1416,
-      Iir_Kind_Parenthesis_Name => 1420,
-      Iir_Kind_External_Constant_Name => 1429,
-      Iir_Kind_External_Signal_Name => 1438,
-      Iir_Kind_External_Variable_Name => 1447,
-      Iir_Kind_Package_Pathname => 1450,
-      Iir_Kind_Absolute_Pathname => 1451,
-      Iir_Kind_Relative_Pathname => 1452,
-      Iir_Kind_Pathname_Element => 1456,
-      Iir_Kind_Base_Attribute => 1458,
-      Iir_Kind_Left_Type_Attribute => 1463,
-      Iir_Kind_Right_Type_Attribute => 1468,
-      Iir_Kind_High_Type_Attribute => 1473,
-      Iir_Kind_Low_Type_Attribute => 1478,
-      Iir_Kind_Ascending_Type_Attribute => 1483,
-      Iir_Kind_Image_Attribute => 1489,
-      Iir_Kind_Value_Attribute => 1495,
-      Iir_Kind_Pos_Attribute => 1501,
-      Iir_Kind_Val_Attribute => 1507,
-      Iir_Kind_Succ_Attribute => 1513,
-      Iir_Kind_Pred_Attribute => 1519,
-      Iir_Kind_Leftof_Attribute => 1525,
-      Iir_Kind_Rightof_Attribute => 1531,
-      Iir_Kind_Delayed_Attribute => 1539,
-      Iir_Kind_Stable_Attribute => 1547,
-      Iir_Kind_Quiet_Attribute => 1555,
-      Iir_Kind_Transaction_Attribute => 1563,
-      Iir_Kind_Event_Attribute => 1567,
-      Iir_Kind_Active_Attribute => 1571,
-      Iir_Kind_Last_Event_Attribute => 1575,
-      Iir_Kind_Last_Active_Attribute => 1579,
-      Iir_Kind_Last_Value_Attribute => 1583,
-      Iir_Kind_Driving_Attribute => 1587,
-      Iir_Kind_Driving_Value_Attribute => 1591,
-      Iir_Kind_Behavior_Attribute => 1591,
-      Iir_Kind_Structure_Attribute => 1591,
-      Iir_Kind_Simple_Name_Attribute => 1598,
-      Iir_Kind_Instance_Name_Attribute => 1603,
-      Iir_Kind_Path_Name_Attribute => 1608,
-      Iir_Kind_Left_Array_Attribute => 1615,
-      Iir_Kind_Right_Array_Attribute => 1622,
-      Iir_Kind_High_Array_Attribute => 1629,
-      Iir_Kind_Low_Array_Attribute => 1636,
-      Iir_Kind_Length_Array_Attribute => 1643,
-      Iir_Kind_Ascending_Array_Attribute => 1650,
-      Iir_Kind_Range_Array_Attribute => 1657,
-      Iir_Kind_Reverse_Range_Array_Attribute => 1664,
-      Iir_Kind_Attribute_Name => 1672
+      Iir_Kind_Procedure_Declaration => 662,
+      Iir_Kind_Function_Body => 672,
+      Iir_Kind_Procedure_Body => 683,
+      Iir_Kind_Object_Alias_Declaration => 695,
+      Iir_Kind_File_Declaration => 710,
+      Iir_Kind_Guard_Signal_Declaration => 723,
+      Iir_Kind_Signal_Declaration => 740,
+      Iir_Kind_Variable_Declaration => 753,
+      Iir_Kind_Constant_Declaration => 767,
+      Iir_Kind_Iterator_Declaration => 779,
+      Iir_Kind_Interface_Constant_Declaration => 795,
+      Iir_Kind_Interface_Variable_Declaration => 811,
+      Iir_Kind_Interface_Signal_Declaration => 832,
+      Iir_Kind_Interface_File_Declaration => 848,
+      Iir_Kind_Interface_Package_Declaration => 857,
+      Iir_Kind_Identity_Operator => 861,
+      Iir_Kind_Negation_Operator => 865,
+      Iir_Kind_Absolute_Operator => 869,
+      Iir_Kind_Not_Operator => 873,
+      Iir_Kind_Condition_Operator => 877,
+      Iir_Kind_Reduction_And_Operator => 881,
+      Iir_Kind_Reduction_Or_Operator => 885,
+      Iir_Kind_Reduction_Nand_Operator => 889,
+      Iir_Kind_Reduction_Nor_Operator => 893,
+      Iir_Kind_Reduction_Xor_Operator => 897,
+      Iir_Kind_Reduction_Xnor_Operator => 901,
+      Iir_Kind_And_Operator => 906,
+      Iir_Kind_Or_Operator => 911,
+      Iir_Kind_Nand_Operator => 916,
+      Iir_Kind_Nor_Operator => 921,
+      Iir_Kind_Xor_Operator => 926,
+      Iir_Kind_Xnor_Operator => 931,
+      Iir_Kind_Equality_Operator => 936,
+      Iir_Kind_Inequality_Operator => 941,
+      Iir_Kind_Less_Than_Operator => 946,
+      Iir_Kind_Less_Than_Or_Equal_Operator => 951,
+      Iir_Kind_Greater_Than_Operator => 956,
+      Iir_Kind_Greater_Than_Or_Equal_Operator => 961,
+      Iir_Kind_Match_Equality_Operator => 966,
+      Iir_Kind_Match_Inequality_Operator => 971,
+      Iir_Kind_Match_Less_Than_Operator => 976,
+      Iir_Kind_Match_Less_Than_Or_Equal_Operator => 981,
+      Iir_Kind_Match_Greater_Than_Operator => 986,
+      Iir_Kind_Match_Greater_Than_Or_Equal_Operator => 991,
+      Iir_Kind_Sll_Operator => 996,
+      Iir_Kind_Sla_Operator => 1001,
+      Iir_Kind_Srl_Operator => 1006,
+      Iir_Kind_Sra_Operator => 1011,
+      Iir_Kind_Rol_Operator => 1016,
+      Iir_Kind_Ror_Operator => 1021,
+      Iir_Kind_Addition_Operator => 1026,
+      Iir_Kind_Substraction_Operator => 1031,
+      Iir_Kind_Concatenation_Operator => 1036,
+      Iir_Kind_Multiplication_Operator => 1041,
+      Iir_Kind_Division_Operator => 1046,
+      Iir_Kind_Modulus_Operator => 1051,
+      Iir_Kind_Remainder_Operator => 1056,
+      Iir_Kind_Exponentiation_Operator => 1061,
+      Iir_Kind_Function_Call => 1069,
+      Iir_Kind_Aggregate => 1075,
+      Iir_Kind_Parenthesis_Expression => 1078,
+      Iir_Kind_Qualified_Expression => 1082,
+      Iir_Kind_Type_Conversion => 1087,
+      Iir_Kind_Allocator_By_Expression => 1091,
+      Iir_Kind_Allocator_By_Subtype => 1095,
+      Iir_Kind_Selected_Element => 1101,
+      Iir_Kind_Dereference => 1106,
+      Iir_Kind_Implicit_Dereference => 1111,
+      Iir_Kind_Slice_Name => 1118,
+      Iir_Kind_Indexed_Name => 1124,
+      Iir_Kind_Psl_Expression => 1126,
+      Iir_Kind_Sensitized_Process_Statement => 1146,
+      Iir_Kind_Process_Statement => 1166,
+      Iir_Kind_Concurrent_Conditional_Signal_Assignment => 1177,
+      Iir_Kind_Concurrent_Selected_Signal_Assignment => 1189,
+      Iir_Kind_Concurrent_Assertion_Statement => 1197,
+      Iir_Kind_Psl_Default_Clock => 1201,
+      Iir_Kind_Psl_Assert_Statement => 1210,
+      Iir_Kind_Psl_Cover_Statement => 1219,
+      Iir_Kind_Concurrent_Procedure_Call_Statement => 1226,
+      Iir_Kind_Block_Statement => 1239,
+      Iir_Kind_If_Generate_Statement => 1249,
+      Iir_Kind_For_Generate_Statement => 1258,
+      Iir_Kind_Component_Instantiation_Statement => 1268,
+      Iir_Kind_Simple_Simultaneous_Statement => 1275,
+      Iir_Kind_Generate_Statement_Body => 1286,
+      Iir_Kind_If_Generate_Else_Clause => 1291,
+      Iir_Kind_Signal_Assignment_Statement => 1300,
+      Iir_Kind_Null_Statement => 1304,
+      Iir_Kind_Assertion_Statement => 1311,
+      Iir_Kind_Report_Statement => 1317,
+      Iir_Kind_Wait_Statement => 1324,
+      Iir_Kind_Variable_Assignment_Statement => 1330,
+      Iir_Kind_Return_Statement => 1336,
+      Iir_Kind_For_Loop_Statement => 1345,
+      Iir_Kind_While_Loop_Statement => 1353,
+      Iir_Kind_Next_Statement => 1359,
+      Iir_Kind_Exit_Statement => 1365,
+      Iir_Kind_Case_Statement => 1373,
+      Iir_Kind_Procedure_Call_Statement => 1379,
+      Iir_Kind_If_Statement => 1388,
+      Iir_Kind_Elsif => 1393,
+      Iir_Kind_Character_Literal => 1400,
+      Iir_Kind_Simple_Name => 1407,
+      Iir_Kind_Selected_Name => 1415,
+      Iir_Kind_Operator_Symbol => 1420,
+      Iir_Kind_Selected_By_All_Name => 1425,
+      Iir_Kind_Parenthesis_Name => 1429,
+      Iir_Kind_External_Constant_Name => 1438,
+      Iir_Kind_External_Signal_Name => 1447,
+      Iir_Kind_External_Variable_Name => 1456,
+      Iir_Kind_Package_Pathname => 1459,
+      Iir_Kind_Absolute_Pathname => 1460,
+      Iir_Kind_Relative_Pathname => 1461,
+      Iir_Kind_Pathname_Element => 1465,
+      Iir_Kind_Base_Attribute => 1467,
+      Iir_Kind_Left_Type_Attribute => 1472,
+      Iir_Kind_Right_Type_Attribute => 1477,
+      Iir_Kind_High_Type_Attribute => 1482,
+      Iir_Kind_Low_Type_Attribute => 1487,
+      Iir_Kind_Ascending_Type_Attribute => 1492,
+      Iir_Kind_Image_Attribute => 1498,
+      Iir_Kind_Value_Attribute => 1504,
+      Iir_Kind_Pos_Attribute => 1510,
+      Iir_Kind_Val_Attribute => 1516,
+      Iir_Kind_Succ_Attribute => 1522,
+      Iir_Kind_Pred_Attribute => 1528,
+      Iir_Kind_Leftof_Attribute => 1534,
+      Iir_Kind_Rightof_Attribute => 1540,
+      Iir_Kind_Delayed_Attribute => 1548,
+      Iir_Kind_Stable_Attribute => 1556,
+      Iir_Kind_Quiet_Attribute => 1564,
+      Iir_Kind_Transaction_Attribute => 1572,
+      Iir_Kind_Event_Attribute => 1576,
+      Iir_Kind_Active_Attribute => 1580,
+      Iir_Kind_Last_Event_Attribute => 1584,
+      Iir_Kind_Last_Active_Attribute => 1588,
+      Iir_Kind_Last_Value_Attribute => 1592,
+      Iir_Kind_Driving_Attribute => 1596,
+      Iir_Kind_Driving_Value_Attribute => 1600,
+      Iir_Kind_Behavior_Attribute => 1600,
+      Iir_Kind_Structure_Attribute => 1600,
+      Iir_Kind_Simple_Name_Attribute => 1607,
+      Iir_Kind_Instance_Name_Attribute => 1612,
+      Iir_Kind_Path_Name_Attribute => 1617,
+      Iir_Kind_Left_Array_Attribute => 1624,
+      Iir_Kind_Right_Array_Attribute => 1631,
+      Iir_Kind_High_Array_Attribute => 1638,
+      Iir_Kind_Low_Array_Attribute => 1645,
+      Iir_Kind_Length_Array_Attribute => 1652,
+      Iir_Kind_Ascending_Array_Attribute => 1659,
+      Iir_Kind_Range_Array_Attribute => 1666,
+      Iir_Kind_Reverse_Range_Array_Attribute => 1673,
+      Iir_Kind_Attribute_Name => 1681
      );
 
    function Get_Fields (K : Iir_Kind) return Fields_Array
@@ -4333,6 +4347,8 @@ package body Nodes_Meta is
             return Get_Has_Mode (N);
          when Field_Has_Class =>
             return Get_Has_Class (N);
+         when Field_Suspend_Flag =>
+            return Get_Suspend_Flag (N);
          when Field_Is_Ref =>
             return Get_Is_Ref (N);
          when others =>
@@ -4439,6 +4455,8 @@ package body Nodes_Meta is
             Set_Has_Mode (N, V);
          when Field_Has_Class =>
             Set_Has_Class (N, V);
+         when Field_Suspend_Flag =>
+            Set_Suspend_Flag (N, V);
          when Field_Is_Ref =>
             Set_Is_Ref (N, V);
          when others =>
@@ -9537,6 +9555,24 @@ package body Nodes_Meta is
       end case;
    end Has_Has_Class;
 
+   function Has_Suspend_Flag (K : Iir_Kind) return Boolean is
+   begin
+      case K is
+         when Iir_Kind_Procedure_Declaration
+           | Iir_Kind_Procedure_Body
+           | Iir_Kind_Process_Statement
+           | Iir_Kind_Concurrent_Procedure_Call_Statement
+           | Iir_Kind_For_Loop_Statement
+           | Iir_Kind_While_Loop_Statement
+           | Iir_Kind_Case_Statement
+           | Iir_Kind_Procedure_Call_Statement
+           | Iir_Kind_If_Statement =>
+            return True;
+         when others =>
+            return False;
+      end case;
+   end Has_Suspend_Flag;
+
    function Has_Is_Ref (K : Iir_Kind) return Boolean is
    begin
       case K is
diff --git a/src/vhdl/nodes_meta.ads b/src/vhdl/nodes_meta.ads
index ce1d33c55..e0face00b 100644
--- a/src/vhdl/nodes_meta.ads
+++ b/src/vhdl/nodes_meta.ads
@@ -347,6 +347,7 @@ package Nodes_Meta is
       Field_Has_Identifier_List,
       Field_Has_Mode,
       Field_Has_Class,
+      Field_Suspend_Flag,
       Field_Is_Ref,
       Field_Psl_Property,
       Field_Psl_Declaration,
@@ -831,6 +832,7 @@ package Nodes_Meta is
    function Has_Has_Identifier_List (K : Iir_Kind) return Boolean;
    function Has_Has_Mode (K : Iir_Kind) return Boolean;
    function Has_Has_Class (K : Iir_Kind) return Boolean;
+   function Has_Suspend_Flag (K : Iir_Kind) return Boolean;
    function Has_Is_Ref (K : Iir_Kind) return Boolean;
    function Has_Psl_Property (K : Iir_Kind) return Boolean;
    function Has_Psl_Declaration (K : Iir_Kind) return Boolean;
diff --git a/src/vhdl/sem.adb b/src/vhdl/sem.adb
index b78b6cf6e..ca44e17df 100644
--- a/src/vhdl/sem.adb
+++ b/src/vhdl/sem.adb
@@ -1776,29 +1776,27 @@ package body Sem is
    --  LRM 2.1  Subprogram Declarations.
    procedure Sem_Subprogram_Declaration (Subprg: Iir)
    is
+      Parent : constant Iir := Get_Parent (Subprg);
       Spec: Iir;
       Interface_Chain : Iir;
       Subprg_Body : Iir;
       Return_Type : Iir;
    begin
       --  Set depth.
-      declare
-         Parent : constant Iir := Get_Parent (Subprg);
-      begin
-         case Get_Kind (Parent) is
-            when Iir_Kind_Function_Declaration
-              | Iir_Kind_Procedure_Declaration =>
-               raise Internal_Error;
-            when Iir_Kind_Function_Body
-              | Iir_Kind_Procedure_Body =>
-               Set_Subprogram_Depth
-                 (Subprg,
-                  Get_Subprogram_Depth
-                  (Get_Subprogram_Specification (Parent)) + 1);
-            when others =>
-               Set_Subprogram_Depth (Subprg, 0);
-         end case;
-      end;
+      case Get_Kind (Parent) is
+         when Iir_Kind_Function_Declaration
+           | Iir_Kind_Procedure_Declaration =>
+            raise Internal_Error;
+         when Iir_Kind_Function_Body
+           | Iir_Kind_Procedure_Body =>
+            Set_Subprogram_Depth
+              (Subprg,
+               Get_Subprogram_Depth
+                 (Get_Subprogram_Specification (Parent)) + 1);
+         when others =>
+            --  FIXME: protected type ?
+            Set_Subprogram_Depth (Subprg, 0);
+      end case;
 
       --  LRM 10.1 Declarative Region
       --  3. A subprogram declaration, together with the corresponding
@@ -1877,6 +1875,14 @@ package body Sem is
                   Inter := Get_Chain (Inter);
                end loop;
             end;
+
+            --  Mark the procedure as suspendable, unless in a std packages.
+            --  This is a minor optimization.
+            if Get_Library (Get_Design_File (Get_Current_Design_Unit))
+              /= Libraries.Std_Library
+            then
+               Set_Suspend_Flag (Subprg, True);
+            end if;
          when others =>
             Error_Kind ("sem_subprogram_declaration", Subprg);
       end case;
@@ -1940,10 +1946,9 @@ package body Sem is
 
    procedure Sem_Subprogram_Body (Subprg : Iir)
    is
-      Spec : Iir;
+      Spec : constant Iir := Get_Subprogram_Specification (Subprg);
       El : Iir;
    begin
-      Spec := Get_Subprogram_Specification (Subprg);
       Set_Impure_Depth (Subprg, Iir_Depth_Pure);
 
       --  LRM 10.1  Declarative regions
@@ -1969,6 +1974,14 @@ package body Sem is
 
       case Get_Kind (Spec) is
          when Iir_Kind_Procedure_Declaration =>
+            if Get_Suspend_Flag (Subprg)
+              and then not Get_Suspend_Flag (Spec)
+            then
+               --  Incoherence: procedures declared in std library are not
+               --  expected to suspend.  This is an internal check.
+               Error_Msg_Sem ("unexpected suspendable procedure", Subprg);
+            end if;
+
             --  Update purity state of procedure if there are no callees.
             case Get_Purity_State (Spec) is
                when Pure
diff --git a/src/vhdl/sem_stmts.adb b/src/vhdl/sem_stmts.adb
index fdc590d12..593ded84c 100644
--- a/src/vhdl/sem_stmts.adb
+++ b/src/vhdl/sem_stmts.adb
@@ -1012,6 +1012,33 @@ package body Sem_Stmts is
       end loop;
    end Sem_Sensitivity_List;
 
+   --  Mark STMT and its parents as suspendable.
+   procedure Mark_Suspendable (Stmt : Iir)
+   is
+      Parent : Iir;
+   begin
+      Parent := Get_Parent (Stmt);
+      loop
+         case Get_Kind (Parent) is
+            when Iir_Kind_Function_Body
+              | Iir_Kind_Sensitized_Process_Statement =>
+               exit;
+            when Iir_Kind_Process_Statement
+              | Iir_Kind_Procedure_Body =>
+               Set_Suspend_Flag (Parent, True);
+               exit;
+            when Iir_Kind_If_Statement
+              | Iir_Kind_While_Loop_Statement
+              | Iir_Kind_For_Loop_Statement
+              | Iir_Kind_Case_Statement =>
+               Set_Suspend_Flag (Parent, True);
+               Parent := Get_Parent (Parent);
+            when others =>
+               Error_Kind ("mark_suspendable", Parent);
+         end case;
+      end loop;
+   end Mark_Suspendable;
+
    procedure Sem_Wait_Statement (Stmt: Iir_Wait_Statement)
    is
       Expr: Iir;
@@ -1054,11 +1081,13 @@ package body Sem_Stmts is
       if Sensitivity_List /= Null_Iir_List then
          Sem_Sensitivity_List (Sensitivity_List);
       end if;
+
       Expr := Get_Condition_Clause (Stmt);
       if Expr /= Null_Iir then
          Expr := Sem_Condition (Expr);
          Set_Condition_Clause (Stmt, Expr);
       end if;
+
       Expr := Get_Timeout_Clause (Stmt);
       if Expr /= Null_Iir then
          Expr := Sem_Expression (Expr, Time_Type_Definition);
@@ -1073,6 +1102,8 @@ package body Sem_Stmts is
             end if;
          end if;
       end if;
+
+      Mark_Suspendable (Stmt);
    end Sem_Wait_Statement;
 
    procedure Sem_Exit_Next_Statement (Stmt : Iir)
@@ -1208,7 +1239,22 @@ package body Sem_Stmts is
             when Iir_Kind_Wait_Statement =>
                Sem_Wait_Statement (Stmt);
             when Iir_Kind_Procedure_Call_Statement =>
-               Sem_Procedure_Call (Get_Procedure_Call (Stmt), Stmt);
+               declare
+                  Call : constant Iir := Get_Procedure_Call (Stmt);
+                  Imp : Iir;
+               begin
+                  Sem_Procedure_Call (Call, Stmt);
+
+                  --  Set suspend flag.
+                  Imp := Get_Implementation (Call);
+                  if Imp /= Null_Iir
+                    and then Get_Kind (Imp) = Iir_Kind_Procedure_Declaration
+                    and then Get_Suspend_Flag (Imp)
+                  then
+                     Set_Suspend_Flag (Stmt, True);
+                     Mark_Suspendable (Stmt);
+                  end if;
+               end;
             when Iir_Kind_Next_Statement
               | Iir_Kind_Exit_Statement =>
                Sem_Exit_Next_Statement (Stmt);