Don't detect native frames at the top of the stack

Author: brandtbucher

Lib/test/test_profiling/test_sampling_profiler.py

@@ -3128,7 +3128,7 @@ def main_loop():
         operator.call(inner)
 
 def inner():
-    # A mixture of native and Python code at the top of the stack:
+    # Python code at the top of the stack:
     for _ in range(1_000_0000):
         pass
 
@@ -3179,11 +3179,8 @@ def test_native_frames_enabled(self):
         # Most samples should have native code in the middle of the stack:
         self.assertTrue(any(";<native>;" in stack for stack in stacks))
 
-        # Some samples should have native code at the top of the stack:
-        self.assertTrue(any(stack.endswith(";<native>") for stack in stacks))
-
-        # Some samples should have Python code at the top of the stack:
-        self.assertTrue(any(not stack.endswith(";<native>") for stack in stacks))
+        # No samples should have native code at the top of the stack:
+        self.assertFalse(any(stack.endswith(";<native>") for stack in stacks))
 
     def test_native_frames_disabled(self):
         """Test that native frames do not appear when native tracking is disabled."""

Modules/_remote_debugging_module.c

@@ -2495,29 +2495,24 @@ process_frame_chain(
             PyErr_SetString(PyExc_RuntimeError, e);
             return -1;
         }
-        _Py_DECLARE_STR(native, "<native>");
-        _Py_DECLARE_STR(gc, "<GC>");
         PyObject *extra_frame = NULL;
         // This frame kicked off the current GC collection:
         if (unwinder->gc && frame_addr == gc_frame) {
+            _Py_DECLARE_STR(gc, "<GC>");
             extra_frame = &_Py_STR(gc);
         }
         // Otherwise, check for native frames to insert:
-        else if (unwinder->native) {
-            // Topmost frame spilled its stack pointer for a native call:
-            if (PyList_GET_SIZE(frame_info) == 0 && stackpointer) {
-                extra_frame = &_Py_STR(native);
-            }
-            // Or, we've reached an interpreter trampoline frame:
-            else if (frame == NULL &&
-                     // Bottommost frame is always native, so skip that one:
-                     next_frame_addr &&
-                     // If the next frame will be reported as a GC frame, then
-                     // don't add an extra native frame below it:
-                     !(unwinder->gc && next_frame_addr == gc_frame))
-            {
-                extra_frame = &_Py_STR(native);
-            }
+        else if (unwinder->native &&
+                 // We've reached an interpreter trampoline frame:
+                 frame == NULL &&
+                 // Bottommost frame is always native, so skip that one:
+                 next_frame_addr &&
+                 // If the next frame will be reported as a GC frame, then
+                 // don't add an extra native frame below it:
+                 !(unwinder->gc && next_frame_addr == gc_frame))
+        {
+            _Py_DECLARE_STR(native, "<native>");
+            extra_frame = &_Py_STR(native);
         }
         if (extra_frame) {
             // Use "~" as file and 0 as line, since that's what pstats uses: