bpo-44590: Lazily allocate frame objects (GH-27077)

* Convert "specials" array to InterpreterFrame struct, adding f_lasti, f_state and other non-debug FrameObject fields to it.

* Refactor, calls pushing the call to the interpreter upward toward _PyEval_Vector.

* Compute f_back when on thread stack, only filling in value when frame object outlives stack invocation.

* Move ownership of InterpreterFrame in generator from frame object to generator object.

* Do not create frame objects for Python calls.

* Do not create frame objects for generators.

1 files changed, 2 insertions, 1 deletions

diff --git a/Python/errors.c b/Python/errors.c
index 118118ffe9..1f84215a13 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -1406,12 +1406,13 @@ _PyErr_WriteUnraisableMsg(const char *err_msg_str, PyObject *obj)
     }
 
     if (exc_tb == NULL) {
-        PyFrameObject *frame = tstate->frame;
+        PyFrameObject *frame = PyThreadState_GetFrame(tstate);
         if (frame != NULL) {
             exc_tb = _PyTraceBack_FromFrame(NULL, frame);
             if (exc_tb == NULL) {
                 _PyErr_Clear(tstate);
             }
+            Py_DECREF(frame);
         }
     }