1 files changed, 28 insertions, 0 deletions
diff --git a/Verify.hs b/Verify.hs
new file mode 100644
index 0000000..18f90ce
--- /dev/null
+++ b/Verify.hs
@@ -0,0 +1,28 @@
+module Verify(verify) where
+
+import AST
+import Defs
+import Intermediate
+
+
+verify :: IRProgram -> Error IRProgram
+verify (IRProgram vars funcs) = IRProgram <$> mapM verifyVar vars <*> mapM verifyFunc funcs
+
+verifyVar :: DVar -> Error DVar
+verifyVar dvar@(DVar _ n e) = case e of
+    ELit _ _ -> return dvar
+    _ -> Left $ "Initialisation of global variable " ++ n ++ " is not a literal"
+
+verifyFunc :: IRFunc -> Error IRFunc
+verifyFunc irfunc@(IRFunc mrt name _ bbs _) =
+    let terms = map (\(BB _ _ term) -> term) bbs
+        (nret', nretr') = unzip $ flip map terms $ \term -> case term of
+            IRet -> (1, 0)
+            IRetr _ -> (0, 1)
+            _ -> (0, 0)
+        (nret, nretr) = (sum nret', sum nretr') :: (Int, Int)
+    in case (mrt, nret, nretr) of
+        (Nothing, _, 0) -> return irfunc
+        (Just _, 0, _) -> return irfunc
+        (Nothing, _, _) -> Left $ "Some code paths of void function '" ++ name ++ "' return a value"
+        (Just _, _, _) -> Left $ "Not all code paths of non-void function '" ++ name ++ "' return a value"