vhdl: detect unused signals and variables.

6 files changed, 42 insertions, 26 deletions

diff --git a/src/vhdl/vhdl-sem.adb b/src/vhdl/vhdl-sem.adb
index 53a61ca3b..503d43293 100644
--- a/src/vhdl/vhdl-sem.adb
+++ b/src/vhdl/vhdl-sem.adb
@@ -545,16 +545,21 @@ package body Vhdl.Sem is
                Check_Port_Association_Bounds_Restrictions
                  (Formal, Actual, Assoc);
                Prefix := Get_Object_Prefix (Object);
-               if Get_Kind (Prefix) = Iir_Kind_Interface_Signal_Declaration
-               then
-                  declare
-                     P : Boolean;
-                     pragma Unreferenced (P);
-                  begin
-                     P := Check_Port_Association_Mode_Restrictions
-                       (Formal_Base, Prefix, Assoc);
-                  end;
-               end if;
+               case Get_Kind (Prefix) is
+                  when Iir_Kind_Interface_Signal_Declaration =>
+                     declare
+                        P : Boolean;
+                        pragma Unreferenced (P);
+                     begin
+                        P := Check_Port_Association_Mode_Restrictions
+                          (Formal_Base, Prefix, Assoc);
+                     end;
+                  when Iir_Kind_Signal_Declaration =>
+                     Set_Use_Flag (Prefix, True);
+                  when others =>
+                     --  FIXME: attributes ?
+                     null;
+               end case;
             else
                --  Expression.
                Set_Collapse_Signal_Flag (Assoc, False);
@@ -580,6 +585,10 @@ package body Vhdl.Sem is
                        (+Actual,
                         "actual expression must be globally static");
                   end if;
+
+                  --  Is it possible to have a globally static name that is
+                  --  not readable ?
+                  Check_Read (Actual);
                else
                   Error_Msg_Sem
                     (+Assoc,
diff --git a/src/vhdl/vhdl-sem_assocs.adb b/src/vhdl/vhdl-sem_assocs.adb
index ee965d0a0..09ed67a85 100644
--- a/src/vhdl/vhdl-sem_assocs.adb
+++ b/src/vhdl/vhdl-sem_assocs.adb
@@ -402,6 +402,15 @@ package body Vhdl.Sem_Assocs is
                      Error_Kind
                        ("check_subprogram_association(3)", Formal_Inter);
                end case;
+
+               case Get_Kind (Prefix) is
+                  when Iir_Kind_Signal_Declaration
+                    | Iir_Kind_Variable_Declaration =>
+                     Set_Use_Flag (Prefix, True);
+                  when others =>
+                     null;
+               end case;
+
             when Iir_Kind_Association_Element_By_Individual =>
                null;
             when others =>
diff --git a/src/vhdl/vhdl-sem_decls.adb b/src/vhdl/vhdl-sem_decls.adb
index 2f29562bf..9e98c26a3 100644
--- a/src/vhdl/vhdl-sem_decls.adb
+++ b/src/vhdl/vhdl-sem_decls.adb
@@ -2227,11 +2227,10 @@ package body Vhdl.Sem_Decls is
             when Iir_Kind_Architecture_Body
               | Iir_Kind_Block_Statement =>
                --  Might be used in a configuration.
-               --  FIXME: create a second level of warning.
-               null;
+               Check_Unused := True;
             when  Iir_Kind_Generate_Statement_Body =>
                --  Might be used in a configuration.
-               null;
+               Check_Unused := True;
             when Iir_Kind_Package_Body
               | Iir_Kind_Protected_Type_Body =>
                --  Check only for declarations of the body.
@@ -2311,6 +2310,12 @@ package body Vhdl.Sem_Decls is
                      Warning_Msg_Sem (Warnid_Unused, +El,
                                       "%n is never referenced", +El);
                   end if;
+               when Iir_Kind_Signal_Declaration
+                 | Iir_Kind_Variable_Declaration =>
+                  if not Get_Use_Flag (El) then
+                     Warning_Msg_Sem (Warnid_Unused, +El,
+                                      "%n is never referenced", +El);
+                  end if;
                when others =>
                   null;
             end case;
diff --git a/src/vhdl/vhdl-sem_expr.adb b/src/vhdl/vhdl-sem_expr.adb
index 31c105c19..da499d449 100644
--- a/src/vhdl/vhdl-sem_expr.adb
+++ b/src/vhdl/vhdl-sem_expr.adb
@@ -4242,9 +4242,11 @@ package body Vhdl.Sem_Expr is
       loop
          case Get_Kind (Obj) is
             when Iir_Kind_Signal_Declaration
-              | Iir_Kind_Constant_Declaration
+              | Iir_Kind_Variable_Declaration =>
+               Set_Use_Flag (Obj, True);
+               return;
+            when Iir_Kind_Constant_Declaration
               | Iir_Kind_Interface_Constant_Declaration
-              | Iir_Kind_Variable_Declaration
               | Iir_Kind_Attribute_Value
               | Iir_Kind_Iterator_Declaration
               | Iir_Kind_Guard_Signal_Declaration =>
@@ -4326,13 +4328,6 @@ package body Vhdl.Sem_Expr is
       end loop;
    end Check_Read;
 
-   procedure Check_Update (Expr : Iir)
-   is
-      pragma Unreferenced (Expr);
-   begin
-      null;
-   end Check_Update;
-
    --  Emit an error if the constant EXPR is deferred and cannot be used in
    --  the current context.
    procedure Check_Constant_Restriction (Expr : Iir; Loc : Iir)
diff --git a/src/vhdl/vhdl-sem_expr.ads b/src/vhdl/vhdl-sem_expr.ads
index c58a26e86..9e6531530 100644
--- a/src/vhdl/vhdl-sem_expr.ads
+++ b/src/vhdl/vhdl-sem_expr.ads
@@ -90,9 +90,6 @@ package Vhdl.Sem_Expr is
    --  Check EXPR can be read.
    procedure Check_Read (Expr : Iir);
 
-   --  Check EXPR can be updated.
-   procedure Check_Update (Expr : Iir);
-
    -- For a procedure call, A_TYPE must be null.
    function Sem_Subprogram_Call (Expr: Iir; A_Type: Iir) return Iir;
 
diff --git a/src/vhdl/vhdl-sem_stmts.adb b/src/vhdl/vhdl-sem_stmts.adb
index e5993cd5c..f8a42f182 100644
--- a/src/vhdl/vhdl-sem_stmts.adb
+++ b/src/vhdl/vhdl-sem_stmts.adb
@@ -332,6 +332,7 @@ package body Vhdl.Sem_Stmts is
             end if;
          when Iir_Kind_Signal_Declaration =>
             Sem_Add_Driver (Target_Object, Stmt);
+            Set_Use_Flag (Target_Prefix, True);
          when Iir_Kind_Guard_Signal_Declaration =>
             Error_Msg_Sem (+Stmt, "implicit GUARD signal cannot be assigned");
             return;
@@ -399,7 +400,7 @@ package body Vhdl.Sem_Stmts is
                return;
             end if;
          when Iir_Kind_Variable_Declaration =>
-            null;
+            Set_Use_Flag (Target_Prefix, True);
          when Iir_Kind_Implicit_Dereference
            | Iir_Kind_Dereference  =>
             --  LRM 3.3