Add PyStackRef_IsMalformed

Author: sergey-miryanov

Include/internal/pycore_stackref.h

@@ -296,6 +296,12 @@ PyStackRef_IsError(_PyStackRef ref)
     return ref.bits == Py_TAG_INVALID;
 }
 
+static inline bool
+PyStackRef_IsMalformed(_PyStackRef ref)
+{
+    return (ref.bits & Py_TAG_BITS) == Py_TAG_INVALID;
+}
+
 static inline bool
 PyStackRef_IsValid(_PyStackRef ref)
 {

Python/ceval.c

@@ -160,7 +160,7 @@ dump_item(_PyStackRef item)
         printf("<NULL>");
         return;
     }
-    if (PyStackRef_IsError(item)) {
+    if (PyStackRef_IsMalformed(item)) {
         printf("<INVALID>");
         return;
     }