support hierarchical calls to functions with no inputs

CHANGELOG.md

@@ -16,6 +16,7 @@
 * Added support for procedural continuous assignments (`assign`/`deassign` and
   `force`/`release`)
 * Added conversion for `do` `while` loops
+* Added support for hierarchical calls to functions with no inputs
 * Added support for passing through DPI imports and exports
 * Added support for passing through functions with output ports
 * Extended applicability of simplified Yosys-compatible `for` loop elaboration

src/Convert.hs

@@ -67,6 +67,7 @@ finalPhases _ =
     [ Convert.NamedBlock.convert
     , Convert.DuplicateGenvar.convert
     , Convert.AsgnOp.convert
+    , Convert.EmptyArgs.convert
     , Convert.FuncRet.convert
     , Convert.TFBlock.convert
     ]
@@ -107,7 +108,6 @@ initialPhases selectExclude =
     , Convert.Unique.convert
     , Convert.EventEdge.convert
     , Convert.LogOp.convert
-    , Convert.EmptyArgs.convert
     , Convert.DoWhile.convert
     , Convert.Foreach.convert
     , Convert.FuncRoutine.convert

src/Convert/EmptyArgs.hs

@@ -8,50 +8,77 @@
 
 module Convert.EmptyArgs (convert) where
 
-import Control.Monad.Writer.Strict
-import qualified Data.Set as Set
-
+import Convert.Scoper
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
-type Idents = Set.Set Identifier
+type SC = Scoper ()
 
 convert :: [AST] -> [AST]
-convert = map $ traverseDescriptions convertDescription
+convert = map $ traverseDescriptions traverseDescription
 
-convertDescription :: Description -> Description
-convertDescription description@Part{} =
-    traverseModuleItems
-        (traverseExprs $ traverseNestedExprs $ convertExpr functions)
-        description'
-    where
-        (description', functions) =
-            runWriter $ traverseModuleItemsM traverseFunctionsM description
-convertDescription other = other
+traverseDescription :: Description -> Description
+traverseDescription =
+    evalScoper . scopePart scoper .
+    traverseModuleItems addDummyArg
+    where scoper = scopeModuleItem
+            traverseDecl traverseModuleItem traverseGenItem traverseStmt
 
-traverseFunctionsM :: ModuleItem -> Writer Idents ModuleItem
-traverseFunctionsM item@(MIPackageItem (Function _ Void _ _ _)) =
-    return item
-traverseFunctionsM (MIPackageItem (Function l t f decls stmts)) = do
-    decls' <-
-        if any isInput decls
-            then return decls
-            else do
-                tell $ Set.singleton f
-                return $ dummyDecl : decls
-    return $ MIPackageItem $ Function l t f decls' stmts
-    where
-        dummyType = IntegerVector TReg Unspecified []
-        dummyDecl = Variable Input dummyType "_sv2v_unused" [] Nil
-        isInput :: Decl -> Bool
-        isInput (Variable Input _ _ _ _) = True
-        isInput _ = False
-traverseFunctionsM other = return other
+-- add a dummy argument to functions with no input ports
+addDummyArg :: ModuleItem -> ModuleItem
+addDummyArg (MIPackageItem (Function l t f decls stmts))
+    | all (not . isInput) decls =
+        MIPackageItem $ Function l t f (dummyDecl : decls) stmts
+addDummyArg other = other
 
-convertExpr :: Idents -> Expr -> Expr
-convertExpr functions (Call (Ident func) (Args [] [])) =
-    Call (Ident func) (Args args [])
-    where args = if Set.member func functions
-            then [RawNum 0]
-            else []
-convertExpr _ other = other
+isInput :: Decl -> Bool
+isInput (Variable Input _ _ _ _) = True
+isInput _ = False
+
+-- write down all declarations so we can look up the dummy arg
+traverseDecl :: Decl -> SC Decl
+traverseDecl decl = do
+    decl' <- case decl of
+        Param    _ _ x _   -> insertElem x () >> return decl
+        ParamType  _ x _   -> insertElem x () >> return decl
+        Variable d t x a e -> do
+            insertElem x ()
+            -- new dummy args have a special name for idempotence
+            return $ if x == dummyIdent
+                then Variable d t dummyIdentFinal a e
+                else decl
+        Net  _ _ _ _ x _ _ -> insertElem x () >> return decl
+        CommentDecl{} -> return decl
+    traverseDeclExprsM traverseExpr decl'
+
+traverseModuleItem :: ModuleItem -> SC ModuleItem
+traverseModuleItem = traverseExprsM traverseExpr
+
+traverseGenItem :: GenItem -> SC GenItem
+traverseGenItem = traverseGenItemExprsM traverseExpr
+
+traverseStmt :: Stmt -> SC Stmt
+traverseStmt = traverseStmtExprsM traverseExpr
+
+-- pass a dummy value to functions which had no inputs
+traverseExpr :: Expr -> SC Expr
+traverseExpr (Call func (Args args [])) = do
+    details <- lookupElemM $ Dot func dummyIdent
+    let args' = if details /= Nothing
+                    then RawNum 0 : args
+                    else args
+    return $ Call func (Args args' [])
+traverseExpr expr =
+    traverseSinglyNestedExprsM traverseExpr expr
+
+dummyIdent :: Identifier
+dummyIdent = '?' : dummyIdentFinal
+
+dummyIdentFinal :: Identifier
+dummyIdentFinal = "_sv2v_unused"
+
+dummyType :: Type
+dummyType = IntegerVector TReg Unspecified []
+
+dummyDecl :: Decl
+dummyDecl = Variable Input dummyType dummyIdent [] Nil

test/core/empty_args_hier.sv

@@ -0,0 +1,32 @@
+interface intf;
+    function automatic integer f;
+        return 1;
+    endfunction
+    if (1) begin : blk
+        function automatic integer f;
+            return 2;
+        endfunction
+    end
+endinterface
+
+module top;
+    intf i();
+    function automatic integer f;
+        return 3;
+    endfunction
+    if (1) begin : blk
+        function automatic integer f;
+            return 4;
+        endfunction
+    end
+    initial begin
+        $display(f());
+        $display(blk.f());
+        $display(i.f());
+        $display(i.blk.f());
+        $display(top.f());
+        $display(top.blk.f());
+        $display(top.i.f());
+        $display(top.i.blk.f());
+    end
+endmodule

test/core/empty_args_hier.v

@@ -0,0 +1,36 @@
+module top;
+    generate
+        if (1) begin : i
+            function automatic integer f;
+                input unused;
+                f = 1;
+            endfunction
+            if (1) begin : blk
+                function automatic integer f;
+                    input unused;
+                    f = 2;
+                endfunction
+            end
+        end
+        function automatic integer f;
+            input unused;
+            f = 3;
+        endfunction
+        if (1) begin : blk
+            function automatic integer f;
+                input unused;
+                f = 4;
+            endfunction
+        end
+    endgenerate
+    initial begin
+        $display(f(0));
+        $display(blk.f(0));
+        $display(i.f(0));
+        $display(i.blk.f(0));
+        $display(top.f(0));
+        $display(top.blk.f(0));
+        $display(top.i.f(0));
+        $display(top.i.blk.f(0));
+    end
+endmodule