[export] Disable side effects on dynamo_graph_capture_for_export and warn user.

Summary:
as title.

Test Plan:
test_dynamo_graph_capture_side_effects

Reviewers:

Subscribers:

Tasks:

Tags:

test/export/test_experimental.py

@@ -3,6 +3,7 @@
 import copy
 import types
 import unittest
+import warnings
 from dataclasses import dataclass
 from typing import Dict, List, Tuple
 
@@ -18,6 +19,9 @@ from torch.testing import FileCheck
 from torch.testing._internal.common_utils import TEST_CUDA
 
 
+GLOBAL_LIST = []
+
+
 @unittest.skipIf(not torch._dynamo.is_dynamo_supported(), "dynamo isn't supported")
 class TestExperiment(TestCase):
     def test_joint_basic(self) -> None:
@@ -611,6 +615,34 @@ def forward(self, args_0):
         self.assertEqual(len(list(gm.buffers())), len(list(foo.buffers())))
         self.assertEqual(len(list(gm.parameters())), len(list(foo.parameters())))
 
+    def test_dynamo_graph_capture_side_effects(self):
+        GLOBAL_LIST.clear()
+
+        def foo(x):
+            z = x + 1
+            GLOBAL_LIST.append(z)
+            return z
+
+        def make_inputs():
+            return (torch.randn(2, 3),)
+
+        trace_inputs = make_inputs()
+        with warnings.catch_warnings(record=True) as w:
+            gm = dynamo_graph_capture_for_export(foo)(*trace_inputs)
+            cnt = 0
+            for entry in w:
+                if "While compiling, we found certain side effects happened" in str(
+                    entry.message
+                ):
+                    cnt += 1
+            self.assertEqual(cnt, 1)
+        self.assertEqual(len(GLOBAL_LIST), 0)
+        test_inputs = make_inputs()
+        gm_results = gm(*test_inputs)
+        self.assertEqual(len(GLOBAL_LIST), 0)
+        self.assertEqual(gm_results, foo(*test_inputs))
+        self.assertEqual(len(GLOBAL_LIST), 1)
+
     @unittest.skipIf(not TEST_CUDA, "CUDA not available")
     def test_dynamo_graph_capture_fx_graph_annotate_overlap_pass(self):
         class DummyOp(torch.autograd.Function):

torch/_dynamo/functional_export.py

@@ -611,6 +611,8 @@ def dynamo_graph_capture_for_export(
     def inner(*args: Any, **kwargs: Any) -> Any:
         assert not torch._dynamo.config.install_free_tensors
         with (
+            torch._dynamo.config.patch(replay_side_effects=False),
+            torch._dynamo.config.patch(side_effect_replay_policy="warn"),
             get_metrics_context(),
             dynamo_timed("fullgraph_capture"),
         ):