From 5fb201de38d38b04f068aec369f60f0ce1e5de6d Mon Sep 17 00:00:00 2001
From: Donghee Na <donghee.na@python.org>
Date: Fri, 17 May 2024 01:43:34 -0400
Subject: [PATCH] gh-119053: Implement the fast path for list.__getitem__

---
 Objects/listobject.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 7070165014f1379..d2f3b2ad352cdb7 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -651,11 +651,18 @@ static PyObject *
 list_item(PyObject *aa, Py_ssize_t i)
 {
     PyListObject *a = (PyListObject *)aa;
+    PyObject *item;
     if (!valid_index(i, PyList_GET_SIZE(a))) {
         PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));
         return NULL;
     }
-    PyObject *item;
+#ifdef Py_GIL_DISABLED
+    PyObject **ob_item = _Py_atomic_load_ptr(&a->ob_item);
+    item = _Py_atomic_load_ptr(&ob_item[i]);
+    if (item && _Py_TryIncrefCompare(&ob_item[i], item)) {
+        return item;
+    }
+#endif
     Py_BEGIN_CRITICAL_SECTION(a);
 #ifdef Py_GIL_DISABLED
     if (!_Py_IsOwnedByCurrentThread((PyObject *)a) && !_PyObject_GC_IS_SHARED(a)) {