Add more cases for prettyprinting types.

ll.py

@@ -13,6 +13,20 @@ class SimpleType(Enum):
     I32 = 4
     I64 = 5
 
+    def __repr__(self):
+        if self == SimpleType.Void:
+            return 'void'
+        elif self == SimpleType.I1:
+            return 'i1'
+        elif self == SimpleType.I8:
+            return 'i8'
+        elif self == SimpleType.I32:
+            return 'i32'
+        elif self == SimpleType.I64:
+            return 'i64'
+        else:
+            return str(self)
+
 
 Program = namedtuple('Program', ['tdecls', 'gdecls', 'fdecls'])
 
@@ -57,12 +71,15 @@ Id = namedtuple('Id', ['val'])
 
 
 def ty2s(ty):
-    if ty == SimpleType.I64:
-        return 'i64'
+    if isinstance(ty, SimpleType):
+        return repr(ty)
+    elif isinstance(ty, PointerType):
+        return ty2s(ty.inner_ty) + '*'
     else:
         # TODO
         print('Unknown type: {}'
               .format(ty))
+        return str(ty)
 
 
 def oper2s(operand):