Differential Revision: [D65362160](https://our.internmc.facebook.com/intern/diff/D65362160)
State after this IR:
1. For the tests that require inference IR, they are replaced with ep.run_decomp({}) so export_for_training_run_decomp is sort of redundant but i guess it is still nice that multiple round of retracing still working. In general, we need some auditing to reduce our redundant testing coverages.
2. After this PR landed and not get reverted for a week or so, i will replace the export_for_training calls with export as they are the same thing now.
3. Added more tests to also cover now "deprecated" old IR by patching export to use old export. For reviewers, please look at the internal version.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/139511
Approved by: https://github.com/ydwu4, https://github.com/angelayi, https://github.com/avikchaudhuri
This PR introduces a new way of building `dynamic_shapes` for export. The idea is to build up a mapping from input tensors to the dynamic shapes that should be assigned to their corresponding fake tensors.
This mapping is automatically converted to the current form of `dynamic_shapes`, which must exactly match the structure of inputs. We do this by using pytree utils.
With the current `dynamic_shapes`, we had to be careful about user-defined classes that are registered with pytree, since such classes are not necessarily polymorphic containers; they may be fine containing tensors, but not dynamic shapes. Thus we had decided to allow input instances of such classes to be associated with dynamic shapes in flattened form. This decision needs to be mirrored in this PR as well. To make it easier to keep these code paths in sync, we refactor the current recursive procedure for associating inputs with dynamic shapes to use the same pytree utils. This needs minor fixes to a few tests where `dynamic_shapes` were not exactly matching the structure of inputs.
Differential Revision: D56551992
Pull Request resolved: https://github.com/pytorch/pytorch/pull/124898
Approved by: https://github.com/zhxchen17