[dynamo] Return gm.forward for eager backend (#124109)

Pull Request resolved: https://github.com/pytorch/pytorch/pull/124109
Approved by: https://github.com/yanboliang, https://github.com/jansel
ghstack dependencies: #124445

torch/_dynamo/backends/debugging.py

@@ -21,7 +21,7 @@ This file contains TorchDynamo backends intended for debugging uses.
 
 @register_backend
 def eager(gm, fake_tensor_inputs):
-    return gm
+    return gm.forward
 
 
 @register_backend

torch/_dynamo/testing.py

@@ -208,7 +208,7 @@ class EagerAndRecordGraphs:
 
     def __call__(self, gm: torch.fx.GraphModule, example_inputs: List[torch.Tensor]):
         self.graphs.append(gm)
-        return gm
+        return gm.forward
 
 
 def strip_comment(code) -> str: