* rs6000-tdep.c (rs6000_frame_this_id): If info->base is 0,

return the null frame ID to terminate the backtrace.

gdb/rs6000-tdep.c

@@ -2550,6 +2550,10 @@ rs6000_frame_this_id (struct frame_info *this_frame, void **this_cache,
 {
   struct rs6000_frame_cache *info = rs6000_frame_cache (this_frame,
 							this_cache);
+  /* This marks the outermost frame.  */
+  if (info->base == 0)
+    return;
+
   (*this_id) = frame_id_build (info->base, get_frame_func (this_frame));
 }