gh-92031: Deoptimize Static Code at Finalization

Lib/test/test_embed.py

@@ -343,6 +343,14 @@ def test_finalize_structseq(self):
         out, err = self.run_embedded_interpreter("test_repeated_init_exec", code)
         self.assertEqual(out, 'Tests passed\n' * INIT_LOOPS)
 
+    def test_quickened_static_code_gets_unquickened_at_Py_FINALIZE(self):
+        # https://github.com/python/cpython/issues/92031
+        code = "import unittest; print('Tests passed')"
+        run = self.run_embedded_interpreter
+        for i in range(50):
+            out, err = run("test_repeated_init_exec", code)
+            self.assertEqual(out, 'Tests passed\n' * INIT_LOOPS)
+
     def test_ucnhash_capi_reset(self):
         # bpo-47182: unicodeobject.c:ucnhash_capi was not reset on shutdown.
         code = "print('\\N{digit nine}')"

Misc/NEWS.d/next/Core and Builtins/2022-04-29-02-50-41.gh-issue-92031.2PpaIN.rst

@@ -0,0 +1 @@
+Deoptimize statically-allocated code objects during ``Py_FINALIZE()`` so that future ``_PyCode_Quicken`` calls always start with unquickened code.

Objects/codeobject.c

@@ -1350,23 +1350,29 @@ _PyCode_GetFreevars(PyCodeObject *co)
     return get_localsplus_names(co, CO_FAST_FREE, co->co_nfreevars);
 }
 
-PyObject *
-_PyCode_GetCode(PyCodeObject *co)
+static void
+deopt_code(_Py_CODEUNIT *instructions, Py_ssize_t len)
 {
-    PyObject *code = PyBytes_FromStringAndSize(NULL, _PyCode_NBYTES(co));
-    if (code == NULL) {
-        return NULL;
-    }
-    _Py_CODEUNIT *instructions = (_Py_CODEUNIT *)PyBytes_AS_STRING(code);
-    for (int i = 0; i < Py_SIZE(co); i++) {
-        _Py_CODEUNIT instruction = _PyCode_CODE(co)[i];
+    for (int i = 0; i < len; i++) {
+        _Py_CODEUNIT instruction = instructions[i];
         int opcode = _PyOpcode_Deopt[_Py_OPCODE(instruction)];
         int caches = _PyOpcode_Caches[opcode];
         instructions[i] = _Py_MAKECODEUNIT(opcode, _Py_OPARG(instruction));
         while (caches--) {
             instructions[++i] = _Py_MAKECODEUNIT(CACHE, 0);
         }
     }
+}
+
+PyObject *
+_PyCode_GetCode(PyCodeObject *co)
+{
+    PyObject *code = PyBytes_FromStringAndSize((const char *)_PyCode_CODE(co),
+                                               _PyCode_NBYTES(co));
+    if (code == NULL) {
+        return NULL;
+    }
+    deopt_code((_Py_CODEUNIT *)PyBytes_AS_STRING(code), Py_SIZE(co));
     return code;
 }
 
@@ -2071,6 +2077,7 @@ _PyStaticCode_Dealloc(PyCodeObject *co)
     if (co->co_warmup == 0) {
          _Py_QuickenedCount--;
     }
+    deopt_code(_PyCode_CODE(co), Py_SIZE(co));
     co->co_warmup = QUICKENING_INITIAL_WARMUP_VALUE;
     PyMem_Free(co->co_extra);
     co->co_extra = NULL;