support evaluating functions as statements

src/Convert.hs

@@ -19,6 +19,7 @@ import qualified Convert.Enum
 import qualified Convert.ForDecl
 import qualified Convert.Foreach
 import qualified Convert.FuncRet
+import qualified Convert.FuncRoutine
 import qualified Convert.Inside
 import qualified Convert.Interface
 import qualified Convert.IntTypes
@@ -58,6 +59,7 @@ phases excludes =
     , selectExclude (Job.Logic    , Convert.Logic.convert)
     , Convert.ForDecl.convert
     , Convert.FuncRet.convert
+    , Convert.FuncRoutine.convert
     , Convert.EmptyArgs.convert
     , Convert.Inside.convert
     , Convert.IntTypes.convert

src/Convert/FuncRoutine.hs

@@ -0,0 +1,45 @@
+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - SystemVerilog allows functions to be called without using their result. For
+ - example, if `f` is a function, one may write `f();` or `void'(f());`, causing
+ - any side effects of `f` to occur in each case. Verilog-2005 does not allow
+ - functions to be called as though they were tasks in this way. This conversion
+ - creates a dummy variable to store the result of the function.
+ -}
+
+module Convert.FuncRoutine (convert) where
+
+import Control.Monad.Writer
+import qualified Data.Set as Set
+
+import Convert.Traverse
+import Language.SystemVerilog.AST
+
+type Idents = Set.Set Identifier
+
+convert :: [AST] -> [AST]
+convert = map $ traverseDescriptions convertDescription
+
+convertDescription :: Description -> Description
+convertDescription (description @ Part{}) =
+    traverseModuleItems (traverseStmts $ convertStmt functions) description
+    where functions = execWriter $
+            collectModuleItemsM collectFunctionsM description
+convertDescription other = other
+
+collectFunctionsM :: ModuleItem -> Writer Idents ()
+collectFunctionsM (MIPackageItem (Function _ _ f _ _)) =
+    tell $ Set.singleton f
+collectFunctionsM _ = return ()
+
+convertStmt :: Idents -> Stmt -> Stmt
+convertStmt functions (Subroutine (Ident func) args) =
+    if Set.member func functions
+        then Block Seq "" [decl] []
+        else Subroutine (Ident func) args
+    where
+        t = TypeOf e
+        e = Call (Ident func) args
+        decl = Variable Local t "sv2v_void" [] (Just e)
+convertStmt _ other = other

src/Language/SystemVerilog/Parser/Parse.y

@@ -941,6 +941,7 @@ StmtNonBlock :: { Stmt }
   | AttributeInstance Stmt                     { StmtAttr $1 $2 }
   | ProceduralAssertionStatement               { Assertion $1 }
   | IncOrDecOperator LHS ";"                   { AsgnBlk (AsgnOp $1) $2 (Number "1") }
+  | "void" "'" "(" Expr CallArgs ")" ";"       { Subroutine $4 $5 }
 
 BlockKWPar :: { BlockKW }
   : "fork" { Par }

sv2v.cabal

@@ -66,6 +66,7 @@ executable sv2v
     Convert.ForDecl
     Convert.Foreach
     Convert.FuncRet
+    Convert.FuncRoutine
     Convert.Inside
     Convert.Interface
     Convert.IntTypes

test/basic/typeof.sv

@@ -4,6 +4,10 @@ module top;
         f = 1'b1 ^ x;
         $display("f(%b) called", x);
     endfunction
+    task t;
+        input x;
+        $display("t(%b) called", x);
+    endtask
 
     initial begin
         type(f(0)) x = f(0);
@@ -11,5 +15,8 @@ module top;
         $display("%b", $bits(x));
         $display("%b", $bits(type(x)));
         $display("%b", $bits(logic [0:1+$bits(type(x))]));
+        f(1);
+        void'(f(0));
+        t(1);
     end
 endmodule

test/basic/typeof.v

@@ -6,6 +6,10 @@ module top;
             $display("f(%b) called", x);
         end
     endfunction
+    task t;
+        input x;
+        $display("t(%b) called", x);
+    endtask
 
     initial begin : block
         reg x;
@@ -14,5 +18,8 @@ module top;
         $display("%b", 32'd1);
         $display("%b", 32'd1);
         $display("%b", 32'd3);
+        x = f(1);
+        x = f(0);
+        t(1);
     end
 endmodule