improved handling of string parameters

- variable-size string parameter conversion restricted to modules which
  depend on the size of the string parameter
- string localparams are typed as appropriately sized vectors
- remove ordered parameter binding logic from string param conversion

src/Convert/StringParam.hs

@@ -1,18 +1,27 @@
+{-# LANGUAGE PatternSynonyms #-}
 {- sv2v
  - Author: Zachary Snow <zach@zachjs.com>
  -
  - Conversion for variable-length string parameters
+ -
+ - While implicitly variable-length string parameters are supported in
+ - Verilog-2005, some usages depend on their type information (e.g., size). In
+ - such instances, an additional parameter is added encoding the width of the
+ - parameter.
  -}
 
 module Convert.StringParam (convert) where
 
 import Control.Monad.Writer.Strict
+import Data.Maybe (mapMaybe)
+import qualified Data.Set as Set
 import qualified Data.Map.Strict as Map
 
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
-type PartStringParams = Map.Map Identifier [(Identifier, Int)]
+type PartStringParams = Map.Map Identifier [Identifier]
+type Idents = Set.Set Identifier
 
 convert :: [AST] -> [AST]
 convert files =
@@ -28,67 +37,70 @@ convert files =
 -- adds automatic width parameters for string parameters
 traverseDescriptionM :: Description -> Writer PartStringParams Description
 traverseDescriptionM (Part attrs extern kw lifetime name ports items) =
-    if null stringParamNames
+    if null candidateStringParams || Set.null stringParamNames
         then return $ Part attrs extern kw lifetime name ports items
         else do
-            tell $ Map.singleton name stringParamIds
+            tell $ Map.singleton name $ Set.toList stringParamNames
             return $ Part attrs extern kw lifetime name ports items'
     where
-        (items', stringParamNames) = runWriter $
-            mapM (traverseNestedModuleItemsM traverseModuleItemM) items
-        allParamNames = parameterNames items
-        stringParamIds = filter (flip elem stringParamNames . fst) $
-            zip allParamNames [0..]
+        items' = map (elaborateStringParam stringParamNames) items
+        candidateStringParams = mapMaybe candidateStringParam items
+        stringParamNames = execWriter $
+            mapM (collectNestedModuleItemsM collectModuleItemM) items
+        collectModuleItemM = collectTypesM $ collectNestedTypesM $
+            collectQueriedIdentsM $ Set.fromList candidateStringParams
 traverseDescriptionM other = return other
 
--- given a list of module items, produces the parameter names in order
-parameterNames :: [ModuleItem] -> [Identifier]
-parameterNames =
-    execWriter . mapM (collectNestedModuleItemsM $ collectDeclsM collectDeclM)
-    where
-        collectDeclM :: Decl -> Writer [Identifier] ()
-        collectDeclM (Param Parameter   _ x _) = tell [x]
-        collectDeclM (ParamType Parameter x _) = tell [x]
-        collectDeclM _ = return ()
+-- utility pattern for candidate string parameter items
+pattern StringParam :: Identifier -> String -> ModuleItem
+pattern StringParam x s =
+    MIPackageItem (Decl (Param Parameter UnknownType x (String s)))
+
+-- write down which parameters may be variable-length strings
+candidateStringParam :: ModuleItem -> Maybe Identifier
+candidateStringParam (MIAttr _ item) = candidateStringParam item
+candidateStringParam (StringParam x _) = Just x
+candidateStringParam _ = Nothing
+
+-- write down which of the given identifiers are subject to type queries
+collectQueriedIdentsM :: Idents -> Type -> Writer Idents ()
+collectQueriedIdentsM idents (TypeOf (Ident x)) =
+    when (Set.member x idents) $ tell $ Set.singleton x
+collectQueriedIdentsM _ _ = return ()
 
 -- rewrite an existing string parameter
-traverseModuleItemM :: ModuleItem -> Writer [Identifier] ModuleItem
-traverseModuleItemM (orig @ (MIPackageItem (Decl (Param Parameter t x e)))) =
-    case (t, e) of
-        (UnknownType, String str) -> do
-            tell [x]
-            return $ Generate $ map wrap [width str, param str]
-            where wrap = GenModuleItem . MIPackageItem . Decl
-        _ -> return orig
+elaborateStringParam :: Idents -> ModuleItem -> ModuleItem
+elaborateStringParam idents (MIAttr attr item) =
+    MIAttr attr $ elaborateStringParam idents item
+elaborateStringParam idents (orig @ (StringParam x str)) =
+    if Set.member x idents
+        then Generate $ map wrap [width, param]
+        else orig
     where
+        wrap = GenModuleItem . MIPackageItem . Decl
         w = widthName x
         r = (BinOp Sub (Ident w) (RawNum 1), RawNum 0)
         t' =  IntegerVector TBit Unspecified [r]
-        defaultWidth str = DimsFn FnBits $ Right $ String str
-        width str = Param Parameter UnknownType w (defaultWidth str)
-        param str = Param Parameter t' x (String str)
-traverseModuleItemM other = return other
+        defaultWidth = DimsFn FnBits $ Right $ String str
+        width = Param Parameter UnknownType w defaultWidth
+        param = Param Parameter t' x (String str)
+elaborateStringParam _ other = other
 
 widthName :: Identifier -> Identifier
 widthName paramName = "_sv2v_width_" ++ paramName
 
--- convert isntances which use the converted string parameters
+-- convert instances which use the converted string parameters
 mapInstance :: PartStringParams -> ModuleItem -> ModuleItem
 mapInstance partStringParams (Instance m params x rs ports) =
     case Map.lookup m partStringParams of
         Nothing -> Instance m params x rs ports
         Just stringParams -> Instance m params' x rs ports
-            where params' = concat $ zipWith (expand stringParams) params [0..]
+            where params' = concatMap (expand stringParams) params
     where
-        expand :: [(Identifier, Int)] -> ParamBinding -> Int -> [ParamBinding]
-        expand _ (paramName, Left t) _ = [(paramName, Left t)]
-        expand stringParams (orig @ ("", Right expr)) idx =
-            if elem idx $ map snd stringParams
-                then [("", Right width), orig]
-                else [orig]
-            where width = DimsFn FnBits $ Right expr
-        expand stringParams (orig @ (paramName, Right expr)) _ =
-            if elem paramName $ map fst stringParams
+        expand :: [Identifier] -> ParamBinding -> [ParamBinding]
+        expand _ (paramName, Left t) = [(paramName, Left t)]
+        expand stringParams (orig @ (paramName, Right expr)) =
+            if elem paramName stringParams
                 then [(widthName paramName, Right width), orig]
                 else [orig]
             where width = DimsFn FnBits $ Right expr

src/Convert/TypeOf.hs

@@ -56,8 +56,8 @@ traverseDeclM decl = do
             return $ case t' of
                 UnpackedType t'' a' -> Variable d t'' ident a' e
                 _ ->                   Variable d t'  ident [] e
-        Param _ UnknownType ident String{} ->
-            insertType ident UnknownType >> return decl'
+        Param Parameter UnknownType ident String{} ->
+            insertType ident (TypeOf $ Ident ident) >> return decl'
         Param _ UnknownType ident e ->
             typeof e >>= insertType ident >> return decl'
         Param _ (Implicit sg rs) ident _ ->

test/basic/string.sv

@@ -1,6 +1,6 @@
 module top;
     localparam FOO = "some useful string";
     localparam type T = type(FOO);
-    localparam T BAR = "some other useful string";
+    localparam T BAR = "some other useful string"; // clipped
     initial $display("'%s' '%s'", FOO, BAR);
 endmodule

test/basic/string.v

@@ -1,5 +1,6 @@
 module top;
     localparam FOO = "some useful string";
-    localparam BAR = "some other useful string";
+    localparam WIDTH = $bits("some useful string");
+    localparam [WIDTH-1:0] BAR = "some other useful string"; // clipped
     initial $display("'%s' '%s'", FOO, BAR);
 endmodule

test/basic/string_param_plain.sv

@@ -0,0 +1,10 @@
+module other;
+    parameter STR = "missing";
+    initial $display("other: STR=%s $bits(STR)=%0d", STR, $bits(STR));
+endmodule
+
+module mod;
+    parameter STR = "missing";
+    initial $display("mod: STR=%s", STR);
+    other #("HI") m();
+endmodule

test/basic/string_param_plain_tb.v

@@ -0,0 +1,4 @@
+module top;
+    mod #("FOO") m1();
+    mod #("BAR") m2();
+endmodule