diff --git a/Tools/cases_generator/lexer.py b/Tools/cases_generator/lexer.py
index 13aee94f2b957c..7c97b919873c65 100644
--- a/Tools/cases_generator/lexer.py
+++ b/Tools/cases_generator/lexer.py
@@ -79,7 +79,7 @@ def choice(*opts: str) -> str:
 opmap = {pattern.replace("\\", "") or "\\": op for op, pattern in operators.items()}
 
 # Macros
-macro = r"# *(ifdef|ifndef|undef|define|error|endif|if|else|include|#)"
+macro = r"# *(ifdef|ifndef|undef|define|error|endif|if +defined|if|else|include|#)"
 CMACRO = "CMACRO"
 
 id_re = r"[a-zA-Z_][0-9a-zA-Z_]*"
diff --git a/Tools/cases_generator/verify.py b/Tools/cases_generator/verify.py
new file mode 100644
index 00000000000000..785e373b0382bc
--- /dev/null
+++ b/Tools/cases_generator/verify.py
@@ -0,0 +1,198 @@
+
+import argparse
+import sys
+
+from analyzer import (
+    Analysis,
+    Instruction,
+    Uop,
+    analyze_files,
+    StackItem,
+    analysis_error,
+)
+from typing import Iterator
+from lexer import Token, LPAREN, IDENTIFIER
+from generators_common import DEFAULT_INPUT
+
+NON_ESCAPING_FUNCTIONS = (
+    "Py_INCREF",
+    "_PyManagedDictPointer_IsValues",
+    "_PyObject_GetManagedDict",
+    "_PyObject_ManagedDictPointer",
+    "_PyObject_InlineValues",
+    "_PyDictValues_AddToInsertionOrder",
+    "Py_DECREF",
+    "Py_XDECREF",
+    "_Py_DECREF_SPECIALIZED",
+    "DECREF_INPUTS_AND_REUSE_FLOAT",
+    "PyUnicode_Append",
+    "_PyLong_IsZero",
+    "Py_ARRAY_LENGTH",
+    "Py_Unicode_GET_LENGTH",
+    "PyUnicode_READ_CHAR",
+    "_Py_SINGLETON",
+    "PyUnicode_GET_LENGTH",
+    "_PyLong_IsCompact",
+    "_PyLong_IsNonNegativeCompact",
+    "_PyLong_CompactValue",
+    "_PyLong_DigitCount",
+    "_Py_NewRef",
+    "_Py_IsImmortal",
+    "PyLong_FromLong",
+    "_Py_STR",
+    "_PyLong_Add",
+    "_PyLong_Multiply",
+    "_PyLong_Subtract",
+    "Py_NewRef",
+    "_PyList_ITEMS",
+    "_PyTuple_ITEMS",
+    "_Py_atomic_load_uintptr_relaxed",
+    "_PyFrame_GetCode",
+    "_PyThreadState_HasStackSpace",
+    "_PyUnicode_Equal",
+    "_PyFrame_SetStackPointer",
+    "_PyType_HasFeature",
+    "PyUnicode_Concat",
+    "PySlice_New",
+    "_Py_LeaveRecursiveCallPy",
+    "maybe_lltrace_resume_frame",
+    "_PyUnicode_JoinArray",
+    "_PyEval_FrameClearAndPop",
+    "_PyFrame_StackPush",
+    "PyCell_New",
+    "PyFloat_AS_DOUBLE",
+    "_PyFrame_PushUnchecked",
+    "Py_FatalError",
+    "assert",
+    "Py_Is",
+    "Py_IsTrue",
+    "Py_IsNone",
+    "Py_IsFalse",
+    "_PyFrame_GetStackPointer"
+    "_PyCode_CODE",
+    "PyCFunction_GET_FLAGS",
+    "_PyErr_Occurred",
+    "_Py_LeaveRecursiveCallTstate",
+    "_Py_EnterRecursiveCallTstateUnchecked",
+    "PyStackRef_FromPyObjectSteal",
+    "PyStackRef_AsPyObjectBorrow",
+    "PyStackRef_AsPyObjectSteal",
+    "PyStackRef_CLOSE",
+    "PyStackRef_DUP",
+    "PyStackRef_CLEAR",
+    "PyStackRef_IsNull",
+    "PyStackRef_TYPE",
+    "PyStackRef_False",
+    "PyStackRef_True",
+    "PyStackRef_None",
+    "PyStackRef_Is",
+    "PyStackRef_FromPyObjectNew",
+    "PyStackRef_AsPyObjectNew",
+    "PyStackRef_FromPyObjectImmortal",
+    "STACKREFS_TO_PYOBJECTS",
+    "STACKREFS_TO_PYOBJECTS_CLEANUP",
+    "CONVERSION_FAILED",
+)
+
+FLOW_CONTROL = {
+    "ESCAPING_CALL",
+    "ERROR_IF",
+    "DEOPT_IF",
+    "ERROR_NO_POP",
+}
+
+DECREFS = {
+    "Py_DECREF",
+    "Py_XDECREF",
+    "Py_CLEAR",
+    "DECREF_INPUTS",
+}
+
+def error(msg: str, tkn:Token) -> None:
+    print(f"{msg} at {tkn.filename}:{tkn.line}")
+
+def check_escaping_call(tkn_iter: Iterator[Token]) -> int:
+    res = 0
+    assert(next(tkn_iter).kind == "LPAREN")
+    parens = 1
+    for tkn in tkn_iter:
+        if tkn.kind == "LPAREN":
+            parens += 1
+        elif tkn.kind == "RPAREN":
+            parens -= 1
+            if parens == 0:
+                return res
+        elif tkn.kind == "GOTO":
+            error("`goto` in 'ESCAPING_CALL'", tkn)
+            res = 1
+        elif tkn.kind == IDENTIFIER:
+            if tkn.text in FLOW_CONTROL:
+                error("Exiting flow control in 'ESCAPING_CALL'", tkn)
+                res = 1
+            if tkn.text in DECREFS:
+                error("DECREF in 'ESCAPING_CALL'", tkn)
+                res = 1
+    return res
+
+def is_macro_name(name: str) -> bool:
+    if name[0] == "_":
+        name = name[1:]
+    if name.startswith("Py"):
+        name = name[2:]
+    return name == name.upper()
+
+def is_getter(name: str) -> bool:
+    return "GET" in name
+
+def check_for_unmarked_escapes(uop: Uop) -> int:
+    res = 0
+    tkns = iter(uop.body)
+    for tkn in tkns:
+        if tkn.kind != IDENTIFIER:
+            continue
+        try:
+            next_tkn = next(tkns)
+        except StopIteration:
+            return False
+        if next_tkn.kind != LPAREN:
+            continue
+        if tkn.text == "ESCAPING_CALL":
+            if check_escaping_call(tkns):
+                res = 1
+        if is_macro_name(tkn.text):
+            continue
+        if is_getter(tkn.text):
+            continue
+        if tkn.text.endswith("Check") or tkn.text.endswith("CheckExact"):
+            continue
+        if "backoff_counter" in tkn.text:
+            continue
+        if tkn.text not in NON_ESCAPING_FUNCTIONS:
+            error(f"Unmarked escaping function '{tkn.text}'", tkn)
+            res = 1
+    return res
+
+def verify_uop(uop: Uop) -> int:
+    return check_for_unmarked_escapes(uop)
+
+def verify(analysis: Analysis) -> int:
+    res = 0
+    for uop in analysis.uops.values():
+        res |= verify_uop(uop)
+    return res
+
+
+arg_parser = argparse.ArgumentParser(
+    description="Verify the bytecode description file.",
+    formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+)
+
+arg_parser.add_argument(
+    "input", nargs=argparse.REMAINDER, help="Instruction definition file(s)"
+)
+
+if __name__ == "__main__":
+    args = arg_parser.parse_args()
+    if len(args.input) == 0:
+        args.input.append(DEFAULT_INPUT)
+    sys.exit(verify(analyze_files(args.input)))