GH-84436: Skip refcounting for known immortals (GH-107605)

1 files changed, 12 insertions, 15 deletions

diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 6b9231a..afe9192 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -41,17 +41,12 @@ Py_LOCAL_INLINE(Py_ssize_t) _PyBytesWriter_GetSize(_PyBytesWriter *writer,
 #define EMPTY (&_Py_SINGLETON(bytes_empty))
 
 
-// Return a borrowed reference to the empty bytes string singleton.
+// Return a reference to the immortal empty bytes string singleton.
 static inline PyObject* bytes_get_empty(void)
 {
-    return &EMPTY->ob_base.ob_base;
-}
-
-
-// Return a strong reference to the empty bytes string singleton.
-static inline PyObject* bytes_new_empty(void)
-{
-    return Py_NewRef(EMPTY);
+    PyObject *empty = &EMPTY->ob_base.ob_base;
+    assert(_Py_IsImmortal(empty));
+    return empty;
 }
 
 
@@ -84,7 +79,7 @@ _PyBytes_FromSize(Py_ssize_t size, int use_calloc)
     assert(size >= 0);
 
     if (size == 0) {
-        return bytes_new_empty();
+        return bytes_get_empty();
     }
 
     if ((size_t)size > (size_t)PY_SSIZE_T_MAX - PyBytesObject_SIZE) {
@@ -123,10 +118,11 @@ PyBytes_FromStringAndSize(const char *str, Py_ssize_t size)
     }
     if (size == 1 && str != NULL) {
         op = CHARACTER(*str & 255);
-        return Py_NewRef(op);
+        assert(_Py_IsImmortal(op));
+        return (PyObject *)op;
     }
     if (size == 0) {
-        return bytes_new_empty();
+        return bytes_get_empty();
     }
 
     op = (PyBytesObject *)_PyBytes_FromSize(size, 0);
@@ -154,11 +150,12 @@ PyBytes_FromString(const char *str)
     }
 
     if (size == 0) {
-        return bytes_new_empty();
+        return bytes_get_empty();
     }
     else if (size == 1) {
         op = CHARACTER(*str & 255);
-        return Py_NewRef(op);
+        assert(_Py_IsImmortal(op));
+        return (PyObject *)op;
     }
 
     /* Inline PyObject_NewVar */
@@ -3065,7 +3062,7 @@ _PyBytes_Resize(PyObject **pv, Py_ssize_t newsize)
         goto error;
     }
     if (newsize == 0) {
-        *pv = bytes_new_empty();
+        *pv = bytes_get_empty();
         Py_DECREF(v);
         return 0;
     }