Make sure we convert borrowed refs on frame

Author: mpage

Include/internal/pycore_stackref.h

@@ -231,6 +231,16 @@ _PyStackRef_StealIfUnborrowed(_PyStackRef stackref)
     return stackref;
 }
 
+static inline bool
+_PyStackRef_IsBorrowed(_PyStackRef stackref)
+{
+    if (PyStackRef_IsNull(stackref) || !PyStackRef_IsDeferred(stackref)) {
+        return false;
+    }
+    PyObject *obj = PyStackRef_AsPyObjectBorrow(stackref);
+    return !(_Py_IsImmortal(obj) || _PyObject_HasDeferredRefcount(obj));
+}
+
 static inline _PyStackRef
 PyStackRef_FromPyObjectNew(PyObject *obj)
 {

Python/frame.c

@@ -57,6 +57,13 @@ take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
     frame->f_executable = PyStackRef_DUP(frame->f_executable);
     int stacktop = (int)(frame->stackpointer - frame->localsplus);
     assert(stacktop >= _PyFrame_GetCode(frame)->co_nlocalsplus);
+    // XXX - Maybe more optimal sequence to do here
+    if (_PyStackRef_IsBorrowed(frame->f_executable)) {
+        Py_INCREF(PyStackRef_AsPyObjectBorrow(frame->f_executable));
+    }
+    if (_PyStackRef_IsBorrowed(frame->f_funcobj)) {
+        Py_INCREF(PyStackRef_AsPyObjectBorrow(frame->f_funcobj));
+    }
     for (int i = 0; i < stacktop; i++) {
         frame->localsplus[i] = _PyStackRef_StealIfUnborrowed(frame->localsplus[i]);
     }