From 8926c8f1ceadf54c32caf59f90a89a9b8e073ed8 Mon Sep 17 00:00:00 2001
From: coolreader18 <33094578+coolreader18@users.noreply.github.com>
Date: Thu, 25 Jul 2019 10:27:04 -0400
Subject: [PATCH 1/2] Add empty tuple optimization

---
 vm/src/pyobject.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/vm/src/pyobject.rs b/vm/src/pyobject.rs
index bc9891511e..3b1c704c5c 100644
--- a/vm/src/pyobject.rs
+++ b/vm/src/pyobject.rs
@@ -146,6 +146,7 @@ pub struct PyContext {
     pub none: PyNoneRef,
     pub ellipsis: PyEllipsisRef,
     pub not_implemented: PyNotImplementedRef,
+    pub empty_tuple: PyTupleRef,
     pub tuple_type: PyClassRef,
     pub tupleiterator_type: PyClassRef,
     pub set_type: PyClassRef,
@@ -324,6 +325,9 @@ impl PyContext {
 
         let true_value = create_object(PyInt::new(BigInt::one()), &bool_type);
         let false_value = create_object(PyInt::new(BigInt::zero()), &bool_type);
+
+        let empty_tuple = create_object(PyTuple::from(vec![]), &tuple_type);
+
         let context = PyContext {
             bool_type,
             memoryview_type,
@@ -382,6 +386,7 @@ impl PyContext {
             weakproxy_type,
             type_type,
             exceptions,
+            empty_tuple,
         };
         objtype::init(&context);
         objlist::init(&context);
@@ -645,7 +650,11 @@ impl PyContext {
     }
 
     pub fn new_tuple(&self, elements: Vec<PyObjectRef>) -> PyObjectRef {
-        PyObject::new(PyTuple::from(elements), self.tuple_type(), None)
+        if elements.is_empty() {
+            self.empty_tuple.clone().into_object()
+        } else {
+            PyObject::new(PyTuple::from(elements), self.tuple_type(), None)
+        }
     }
 
     pub fn new_list(&self, elements: Vec<PyObjectRef>) -> PyObjectRef {

From 8aee7457b7622aff928018200895236ef7bba9c5 Mon Sep 17 00:00:00 2001
From: coolreader18 <33094578+coolreader18@users.noreply.github.com>
Date: Thu, 25 Jul 2019 10:28:13 -0400
Subject: [PATCH 2/2] Add test snippet for empty tuple

---
 tests/snippets/tuple.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tests/snippets/tuple.py b/tests/snippets/tuple.py
index 86f12fe943..f7d880e901 100644
--- a/tests/snippets/tuple.py
+++ b/tests/snippets/tuple.py
@@ -38,3 +38,9 @@ def __eq__(self, x):
 a = (1, 2, 3)
 a += 1,
 assert a == (1, 2, 3, 1)
+
+assert () is ()
+
+a = ()
+b = ()
+assert a is b