[Dynamo] Guard serialization for FUNCTION_MATCH (#152727)

Unsupported because it uses unsupported ID_MATCH.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/152727
Approved by: https://github.com/jansel
ghstack dependencies: #152725

test/dynamo/test_guard_serialization.py

@@ -621,6 +621,22 @@ class TestGuardSerialization(torch._inductor.test_case.TestCase):
             ):
                 self._test_serialization("NN_MODULE", fn, m, x)
 
+    def test_function_match(self):
+        def fn(x):
+            # usage of this context manager installs a FUNCTION_MATCH guard
+            with torch.no_grad():
+                y = x * 2
+            return y
+
+        x = torch.randn(3)
+
+        # we don't support FUNCTION_MATCH because it adds an ID_MATCH guard, and we don't
+        # support that in serialization
+        with self.assertRaisesRegex(
+            RuntimeError, "FUNCTION_MATCH guard cannot be serialized."
+        ):
+            self._test_serialization("FUNCTION_MATCH", fn, x)
+
     def test_dict_version(self):
         def fn(x):
             return pytree.tree_leaves(x)[0] + 1

torch/_dynamo/guards.py

@@ -1761,6 +1761,9 @@ class GuardBuilder(GuardBuilderBase):
 
     def FUNCTION_MATCH(self, guard: Guard):
         """things like torch.add and user defined functions"""
+        # don't support this in serialization because it uses unsupported ID_MATCH
+        if self.serialization_mode == "save":
+            raise RuntimeError("FUNCTION_MATCH guard cannot be serialized.")
         return self.ID_MATCH(guard)
 
     def CLOSURE_MATCH(self, guard: Guard):