Resolve #7: correctly return function result

2 files changed, 36 insertions, 24 deletions

diff --git a/Sil/Compile.icl b/Sil/Compile.icl
index 22b6532..7e836b8 100644
--- a/Sil/Compile.icl
+++ b/Sil/Compile.icl
@@ -129,7 +129,13 @@ getTypeResolver = gets typeresolvers >>= \trs -> pure $ \n ->
 		[]    -> Nothing
 
 reserveVar :: Int Name -> Gen Int
-reserveVar i n = modify (\cs -> {cs & addresses='M'.put n i cs.addresses}) $> (i+1)
+reserveVar i n = modify (\cs -> {cs & addresses='M'.put n i cs.addresses}) *> comment ("Reserved " <+ i <+ " for " <+ n) $> (i+1)
+
+findVar :: Name -> Gen Int
+findVar n = gets stackoffset >>= \so ->
+	gets addresses >>= \addr -> case 'M'.get n addr of
+		Just i  -> comment (n <+ " is at " <+ i <+ ", with so " <+ so <+ " so " <+ (so-i-1)) $> so - i - 1
+		Nothing -> error $ UndefinedName n
 
 addFunction :: Function -> Gen ()
 addFunction f = modify (\cs -> {cs & symbols='M'.put f.f_name fs cs.symbols})
@@ -189,7 +195,9 @@ where
 		tell [ 'ABC'.Annotation $ 'ABC'.OAnnot args []
 		     , 'ABC'.Label $ toLabel f.f_name
 		     ] *>
-		foldM reserveVar locals [a.arg_name \\ a <- reverse f.f_args] *>
+		tell (repeatn retSize 'ABC'.Create) *> growStack retSize *>
+		foldM reserveVar 0 [a.arg_name \\ a <- f.f_args] *>
+		growStack (sum [typeSize a.arg_type \\ a <- f.f_args]) *>
 		newReturn cleanup` *>
 		pushTypeResolver typeresolver *>
 		gen f.f_code *>
@@ -199,17 +207,13 @@ where
 		tell ['ABC'.Rtn] *>
 		popReturn
 	where
-		cleanup` = case f.f_args of
-			[] -> [ 'ABC'.Annotation $ 'ABC'.DAnnot retSize []
-			      ]
-			_  -> [ 'ABC'.Comment "Cleanup"] ++
-			      [ 'ABC'.Update_a i (args+i) \\ i <- [0..retSize-1] ] ++
-			      [ 'ABC'.Pop_a args
-			      , 'ABC'.Annotation $ 'ABC'.DAnnot retSize []
-			      ]
+		cleanup` =
+			[ 'ABC'.Comment "Cleanup"
+			, 'ABC'.Pop_a args
+			, 'ABC'.Annotation $ 'ABC'.DAnnot retSize []
+			]
 		retSize = typeSize f.f_type
 		args = length f.f_args
-		locals = length f.f_code.cb_init
 
 		typeresolver :: Name -> Maybe (MaybeError TypeError Type)
 		typeresolver n = listToMaybe [Ok a.arg_type \\ a <- f.f_args | a.arg_name == n]
@@ -218,7 +222,8 @@ instance gen CodeBlock
 where
 	gen cb =
 		storeStackOffset *>
-		foldM reserveVar 0 [i.init_name \\ i <- cb.cb_init] *>
+		gets stackoffset >>= \so ->
+		foldM reserveVar so [i.init_name \\ i <- cb.cb_init] *>
 		mapM_ gen cb.cb_init *>
 		addToReturn cleanup` *>
 		pushTypeResolver typeresolver *>
@@ -242,13 +247,13 @@ where
 
 instance gen Statement
 where
-	gen st=:(Declaration n e) = gets addresses >>= \addrs -> case 'M'.get n addrs of
-		Just i -> checkTypeName n e *>
-		          comment (toString st) *>
-		          gen e *>
-		          tell ['ABC'.Update_a 0 $ i+1, 'ABC'.Pop_a 1] *> // TODO should depend on size of return type
-		          shrinkStack 1
-		_      -> liftT $ Error $ UndefinedName n
+	gen st=:(Declaration n e) =
+		checkTypeName n e *>
+		comment (toString st) *>
+		gen e *>
+		findVar n >>= \loc ->
+		tell ['ABC'.Update_a 0 loc, 'ABC'.Pop_a 1] *> // TODO should depend on size of return type
+		shrinkStack 1
 	gen (Application e) =
 		comment "Application" *>
 		gen e *>
@@ -260,6 +265,10 @@ where
 	gen (Return (Just e)) =
 		comment "Return" *>
 		gen e *>
+		gets stackoffset >>= \so ->
+		tell [ 'ABC'.Update_a 0 (so-1)
+		     , 'ABC'.Pop_a 1
+		     ] *> shrinkStack 1 *>
 		cleanup *>
 		tell ['ABC'.Rtn]
 	gen (Return Nothing) =
@@ -277,6 +286,7 @@ where
 		genifblock end (cond, cb) =
 			checkType TBool cond *>
 			fresh "ifelse" >>= \else ->
+			comment ("(else) if " <+ cond) *>
 			gen cond *>
 			toBStack 'ABC'.BT_Bool 1 *>
 			tell [ 'ABC'.JmpFalse else ] *>
@@ -301,11 +311,8 @@ where
 instance gen Expression
 where
 	gen (Name n) =
-		gets stackoffset >>= \so ->
-		gets addresses >>= \addrs ->
-		case 'M'.get n addrs of
-			Just i -> tell ['ABC'.Push_a $ i + so] *> growStack 1
-			_      -> liftT $ Error $ UndefinedName n
+		findVar n >>= \loc ->
+		tell ['ABC'.Push_a $ loc] *> growStack 1
 	gen (Literal (BLit b)) = tell ['ABC'.Create, 'ABC'.FillB b 0] *> growStack 1
 	gen (Literal (ILit i)) = tell ['ABC'.Create, 'ABC'.FillI i 0] *> growStack 1
 	gen (App n args) = gets addresses >>= \addrs -> case 'M'.get n addrs of
diff --git a/examples/issue-7.sil b/examples/issue-7.sil
new file mode 100644
index 0000000..81fea42
--- /dev/null
+++ b/examples/issue-7.sil
@@ -0,0 +1,5 @@
+Bool main () {
+	Int x;
+	x := 10;
+	return True;
+}