support and conversion for -> and <->

src/Convert.hs

@@ -22,6 +22,7 @@ import qualified Convert.Interface
 import qualified Convert.IntTypes
 import qualified Convert.KWArgs
 import qualified Convert.Logic
+import qualified Convert.LogOp
 import qualified Convert.NamedBlock
 import qualified Convert.NestPI
 import qualified Convert.Package
@@ -52,6 +53,7 @@ phases excludes =
     , Convert.EmptyArgs.convert
     , Convert.IntTypes.convert
     , Convert.KWArgs.convert
+    , Convert.LogOp.convert
     , Convert.PackedArray.convert
     , Convert.DimensionQuery.convert
     , Convert.ParamType.convert

src/Convert/LogOp.hs

+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - Conversion for logical implication (->) and logical equality (<->) operators.
+ -
+ - We convert `a -> b` to `!a || b`, as per the definition of implication.
+ -
+ - We convert `a <-> b` to `!a = !b`. Note that we can't simply use `a = b` as
+ - `1 != 2`, but `1 <-> 2`.
+ -}
+
+module Convert.LogOp (convert) where
+
+import Convert.Traverse
+import Language.SystemVerilog.AST
+
+convert :: [AST] -> [AST]
+convert =
+    map $
+    traverseDescriptions $ traverseModuleItems $
+    traverseExprs $ traverseNestedExprs convertExpr
+
+convertExpr :: Expr -> Expr
+convertExpr (BinOp LogEq a b) =
+    BinOp Eq (UniOp LogNot a) (UniOp LogNot b)
+convertExpr (BinOp LogImp a b) =
+    BinOp LogOr (UniOp LogNot a) b
+convertExpr other = other

src/Language/SystemVerilog/AST/Op.hs

@@ -40,6 +40,8 @@ instance Show UniOp where
 data BinOp
     = LogAnd
     | LogOr
+    | LogImp
+    | LogEq
     | BitAnd
     | BitXor
     | BitXnor
@@ -69,6 +71,8 @@ data BinOp
 instance Show BinOp where
     show LogAnd  = "&&"
     show LogOr   = "||"
+    show LogImp  = "->"
+    show LogEq   = "<->"
     show BitAnd  = "&"
     show BitXor  = "^"
     show BitXnor = "~^"

src/Language/SystemVerilog/Parser/Lex.x

@@ -458,6 +458,7 @@ tokens :-
     "<<<"              { tok Sym_lt_lt_lt }
     "<<="              { tok Sym_lt_lt_eq }
     ">>="              { tok Sym_gt_gt_eq }
+    "<->"              { tok Sym_lt_dash_gt }
     "|->"              { tok Sym_bar_dash_gt }
     "|=>"              { tok Sym_bar_eq_gt }
     "[->"              { tok Sym_brack_l_dash_gt }

src/Language/SystemVerilog/Parser/Parse.y

@@ -366,6 +366,7 @@ time               { Token Lit_time        _ _ }
 "<<<"              { Token Sym_lt_lt_lt _ _ }
 "<<="              { Token Sym_lt_lt_eq _ _ }
 ">>="              { Token Sym_gt_gt_eq _ _ }
+"<->"              { Token Sym_lt_dash_gt _ _ }
 "|->"              { Token Sym_bar_dash_gt _ _ }
 "|=>"              { Token Sym_bar_eq_gt _ _ }
 "[->"              { Token Sym_brack_l_dash_gt _ _ }
@@ -391,6 +392,7 @@ time               { Token Lit_time        _ _ }
 %right "throughout"
 %left "##"
 %nonassoc "[*]" "[=]" "[->]"
+%right "->" "<->"
 %right "?" ":"
 %left  "||"
 %left  "&&"
@@ -1042,6 +1044,8 @@ Expr :: { Expr }
   -- binary expressions
   | Expr "||"  Expr { BinOp LogOr  $1 $3 }
   | Expr "&&"  Expr { BinOp LogAnd $1 $3 }
+  | Expr "->"  Expr { BinOp LogImp $1 $3 }
+  | Expr "<->" Expr { BinOp LogEq  $1 $3 }
   | Expr "|"   Expr { BinOp BitOr  $1 $3 }
   | Expr "^"   Expr { BinOp BitXor $1 $3 }
   | Expr "&"   Expr { BinOp BitAnd $1 $3 }

src/Language/SystemVerilog/Parser/Tokens.hs

@@ -366,6 +366,7 @@ data TokenName
     | Sym_lt_lt_lt
     | Sym_lt_lt_eq
     | Sym_gt_gt_eq
+    | Sym_lt_dash_gt
     | Sym_bar_dash_gt
     | Sym_bar_eq_gt
     | Sym_pound_dash_pound

sv2v.cabal

@@ -67,6 +67,7 @@ executable sv2v
     Convert.IntTypes
     Convert.KWArgs
     Convert.Logic
+    Convert.LogOp
     Convert.NamedBlock
     Convert.NestPI
     Convert.Package

test/basic/log_op.sv

+module top;
+    function log_imp;
+        input integer a;
+        input integer b;
+        return a -> b;
+    endfunction
+    function log_eq;
+        input integer a;
+        input integer b;
+        return a <-> b;
+    endfunction
+    initial
+        for (integer a = -2; a <= 2; a++)
+            for (integer b = -2; b <= 2; b++)
+                $display(log_imp(a, b), log_eq(a, b));
+endmodule

test/basic/log_op.v

+module top;
+    function log_imp;
+        input integer a;
+        input integer b;
+        log_imp = !a || b;
+    endfunction
+    function log_eq;
+        input integer a;
+        input integer b;
+        log_eq = !a == !b;
+    endfunction
+    initial begin : foo
+        integer a, b;
+        for (a = -2; a <= 2; a = a + 1)
+            for (b = -2; b <= 2; b = b + 1)
+                $display(log_imp(a, b), log_eq(a, b));
+    end
+endmodule