gh-146261: JIT: protect against function version changes

Lib/test/test_capi/test_opt.py

@@ -4288,9 +4288,35 @@ def g():
         PYTHON_JIT="1", PYTHON_JIT_STRESS="1")
         self.assertEqual(result[0].rc, 0, result)
 
+    def test_func_version_watched_and_invalidated(self):
+        def testfunc(n):
+            for i in range(n):
+                # Only works on functions promoted to constants
+                global_identity_code_will_be_modified(i)
+
+        testfunc(TIER2_THRESHOLD)
+
+        ex = get_first_executor(testfunc)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertIn("_PUSH_FRAME", uops)
+        # Both should be not present, as this is a call
+        # to a simple function with a known function version.
+        self.assertNotIn("_CHECK_FUNCTION_VERSION_INLINE", uops)
+        self.assertNotIn("_CHECK_FUNCTION_VERSION", uops)
+
+        global_identity_code_will_be_modified.__code__ = (lambda a:a).__code__
+        ex = get_first_executor(testfunc)
+        # Invalidated and removed.
+        self.assertIsNone(ex)
+
+
 def global_identity(x):
     return x
 
+def global_identity_code_will_be_modified(x):
+    return x
+
 class TestObject:
     def test(self, *args, **kwargs):
         return args[0]

Objects/funcobject.c

@@ -8,6 +8,7 @@
 #include "pycore_modsupport.h"    // _PyArg_NoKeywords()
 #include "pycore_object.h"        // _PyObject_GC_UNTRACK()
 #include "pycore_object_deferred.h" // _PyObject_SetDeferredRefcount()
+#include "pycore_optimizer.h"
 #include "pycore_pyerrors.h"      // _PyErr_Occurred()
 #include "pycore_setobject.h"     // _PySet_NextEntry()
 #include "pycore_stats.h"
@@ -63,6 +64,9 @@ handle_func_event(PyFunction_WatchEvent event, PyFunctionObject *func,
         case PyFunction_EVENT_MODIFY_DEFAULTS:
         case PyFunction_EVENT_MODIFY_KWDEFAULTS:
         case PyFunction_EVENT_MODIFY_QUALNAME:
+#if _Py_TIER2
+            _Py_Executors_InvalidateDependency(interp, func, 1);
+#endif
             RARE_EVENT_INTERP_INC(interp, func_modification);
             break;
         default:

Python/optimizer_bytecodes.c

@@ -864,6 +864,15 @@ dummy_func(void) {
     }
 
     op(_CHECK_FUNCTION_VERSION, (func_version/2, callable, self_or_null, unused[oparg] -- callable, self_or_null, unused[oparg])) {
+        PyObject *func = sym_get_probable_value(callable);
+        if (func == NULL || !PyFunction_Check(func)) {
+            ctx->contradiction = true;
+            ctx->done = true;
+            break;
+        }
+        // This could pass due to a global promoted const.
+        // So we need to add it to the dependencies on both branches.
+        _Py_BloomFilter_Add(dependencies, func);
         if (sym_get_func_version(callable) == func_version) {
             REPLACE_OP(this_instr, _NOP, 0, 0);
         }