From 1e197e63e21f77b102ff2601a549dda4b6439455 Mon Sep 17 00:00:00 2001
From: Mark Shannon <mark@hotpy.org>
Date: Thu, 10 Nov 2022 04:34:57 -0800
Subject: GH-96421: Insert shim frame on entry to interpreter (GH-96319)

* Adds EXIT_INTERPRETER instruction to exit PyEval_EvalDefault()

* Simplifies RETURN_VALUE, YIELD_VALUE and RETURN_GENERATOR instructions as they no longer need to check for entry frames.
---
 Python/frame.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'Python/frame.c')

diff --git a/Python/frame.c b/Python/frame.c
index 89f084b110..52f6ef4282 100644
--- a/Python/frame.c
+++ b/Python/frame.c
@@ -80,6 +80,7 @@ _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest)
 static void
 take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
 {
+    assert(frame->owner != FRAME_OWNED_BY_CSTACK);
     assert(frame->owner != FRAME_OWNED_BY_FRAME_OBJECT);
     assert(frame->owner != FRAME_CLEARED);
     Py_ssize_t size = ((char*)&frame->localsplus[frame->stacktop]) - (char *)frame;
@@ -99,7 +100,9 @@ take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
     while (prev && _PyFrame_IsIncomplete(prev)) {
         prev = prev->previous;
     }
+    frame->previous = NULL;
     if (prev) {
+        assert(prev->owner != FRAME_OWNED_BY_CSTACK);
         /* Link PyFrameObjects.f_back and remove link through _PyInterpreterFrame.previous */
         PyFrameObject *back = _PyFrame_GetFrameObject(prev);
         if (back == NULL) {
@@ -111,7 +114,6 @@ take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
         else {
             f->f_back = (PyFrameObject *)Py_NewRef(back);
         }
-        frame->previous = NULL;
     }
     if (!_PyObject_GC_IS_TRACKED((PyObject *)f)) {
         _PyObject_GC_TRACK((PyObject *)f);
-- 
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