simplify handles shadowing via vars and genvars

src/Convert/Simplify.hs

@@ -42,6 +42,8 @@ traverseDeclM decl = do
             where t = IntegerVector TLogic sg rs
         Param Localparam t x e ->
             insertExpr x $ Cast (Left t) e
+        Variable _ _ x _ _ -> insertElem x Nil
+        Net  _ _ _ _ x _ _ -> insertElem x Nil
         _ -> return ()
     return decl'
 
@@ -66,6 +68,8 @@ isSimpleExpr (Cast Left{} e) = isSimpleExpr e
 isSimpleExpr _ = False
 
 traverseModuleItemM :: ModuleItem -> Scoper Expr ModuleItem
+traverseModuleItemM (Genvar x) =
+    insertElem x Nil >> return (Genvar x)
 traverseModuleItemM (Instance m p x rs l) = do
     p' <- mapM paramBindingMapper p
     traverseExprsM traverseExprM $ Instance m p' x rs l
@@ -147,8 +151,8 @@ substitute scopes expr =
         substitute' :: Expr -> Expr
         substitute' (Ident x) =
             case lookupElem scopes x of
-                Nothing -> Ident x
-                Just (_, _, e) -> e
+                Just (_, _, e) | e /= Nil -> e
+                _ -> Ident x
         substitute' other =
             traverseSinglyNestedExprs substitute' other
 

test/basic/simplify_arg_shadow.sv

@@ -0,0 +1,8 @@
+module top;
+    localparam i = 1234;
+    function automatic integer f;
+        input integer i;
+        f = i + 1;
+    endfunction
+    initial $display(i, f(0), f(i + 1));
+endmodule

test/basic/simplify_genvar_shadow.sv

@@ -0,0 +1,8 @@
+module top;
+    localparam i = 1234;
+    if (1) begin
+        genvar i;
+        for (i = 0; i < 10; i = i + 1)
+            initial $display(i > 5 ? i + 100 : i - 100);
+    end
+endmodule