gh-141786 Fix missing parent executor during trace

Author: caje731

Python/ceval.c

@@ -1123,6 +1123,10 @@ stop_tracing_and_jit(PyThreadState *tstate, _PyInterpreterFrame *frame)
     else {
         // Likewise, we hold a strong reference to the executor containing this exit, so the exit is guaranteed
         // to be valid to access.
+        if (!exit->executor->vm_data.linked || !exit->executor->vm_data.valid) {
+            // gh-141786 Parent executor is either unlinked or invalid - cannot optimize.
+            err = -1;
+        }
         if (err <= 0) {
             exit->temperature = restart_backoff_counter(exit->temperature);
         }

Python/optimizer.c

@@ -140,6 +140,11 @@ _PyOptimizer_Optimize(
     }
     assert(!interp->compiling);
     assert(_tstate->jit_tracer_state.initial_state.stack_depth >= 0);
+    _PyExitData *exit = _tstate->jit_tracer_state.initial_state.exit;
+    if (exit != NULL && (!exit->executor->vm_data.linked || !exit->executor->vm_data.valid)) {
+        // gh-141786 Parent executor is either unlinked or invalid - cannot optimize.
+        return 0;
+    }
 #ifndef Py_GIL_DISABLED
     assert(_tstate->jit_tracer_state.initial_state.func != NULL);
     interp->compiling = true;
@@ -185,7 +190,6 @@ _PyOptimizer_Optimize(
     else {
         executor->vm_data.code = NULL;
     }
-    _PyExitData *exit = _tstate->jit_tracer_state.initial_state.exit;
     if (exit != NULL) {
         exit->executor = executor;
     }