misc fixes

src/codegen/irgen/irgenerator.cpp

@@ -2627,7 +2627,8 @@ private:
                 llvm::Value* v;
                 if (phi_type == phi_type->getBoxType()) {
                     v = emitter.getNone()->getValue();
-                    _setVRegIfUserVisible(*it, [&]() { return v; }, NULL);
+                    if (new_state != DEAD)
+                        _setVRegIfUserVisible(*it, [&]() { return v; }, NULL);
                 } else {
                     v = llvm::UndefValue::get(phi_type->llvmType());
                 }

src/runtime/tuple.cpp

@@ -385,7 +385,7 @@ extern "C" Box* tupleNew(Box* _cls, BoxedTuple* args, BoxedDict* kwargs) {
         return BoxedTuple::create(elts.size(), &elts[0], cls);
     } else {
         if (cls == tuple_cls)
-            return EmptyTuple;
+            return incref(EmptyTuple);
         return BoxedTuple::create(0, cls);
     }
 }

src/runtime/types.cpp

@@ -2895,7 +2895,7 @@ static Box* typeAbstractMethods(Box* _type, void*) {
     if (!mod) {
         raiseExcHelper(AttributeError, "__abstractmethods__");
     }
-    return mod;
+    return incref(mod);
 }
 
 static PyObject* object_new(PyTypeObject* type, PyObject* args, PyObject* kwds) noexcept {