[dynamo] raise observed exception for module attribute errors (pytorch#153659)

Fixes pytorch#153605

Pull Request resolved: pytorch#153659
Approved by: https://github.com/StrongerXi

Author: williamwen42

test/dynamo/test_repros.py

@@ -7254,6 +7254,23 @@ def f(x):
         actual = torch.autograd.grad(c_out.sum(), inputs=(x,))
         self.assertEqual(expected, actual)
 
+    def test_module_attribute_error(self):
+        @torch.compile(backend="eager")
+        def f1(x):
+            return torch._bar(x)
+
+        @torch.compile(backend="eager")
+        def f2(x):
+            try:
+                return torch._bar(x)
+            except AttributeError:
+                return x + 1
+
+        with self.assertRaises(AttributeError):
+            f1(torch.ones(3))
+
+        self.assertEqual(f2(torch.ones(3)), torch.ones(3) + 1)
+
 
 instantiate_parametrized_tests(ReproTests)
 

torch/_dynamo/variables/misc.py

@@ -1270,7 +1270,10 @@ def var_getattr(self, tx: "InstructionTranslator", name):
             return tx.output.side_effects.load_attr(self, name)
 
         if self.is_torch or name not in self.value.__dict__:
-            attr_value = getattr(self.value, name)
+            try:
+                attr_value = getattr(self.value, name)
+            except AttributeError:
+                raise_observed_exception(AttributeError, tx)
         else:
             attr_value = self.value.__dict__[name]