Changes:
1. Add `_private_register_pytree_node` API in both C++ and Python pytree. In C++ pytree, the API will only register pytree node for C++ pytree. In Python pytree, the API will only register pytree node for Python pytree.
2. Do not allow registering a type as pytree node twice in the Python pytree.
3. Add thread lock to the Python pytree node register API.
4. The old `_register_pytree_node` API will call the `_private_register_pytree_node` API and raise a deprecation warning.
5. Add a new `register_pytree_node` API to register node type in both C++ and Python implementations.
6. Add tests to ensure a warning will be raised when the old private function is called.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112111
Approved by: https://github.com/zou3519
Previous discussion: https://github.com/pytorch/pytorch/pull/109476
In this PR, I made following additions to the original PR:
1) Unlifted graph module now runs the runtime assertions in its' forward call.
2) When we retrace, we make sure we run the assertions to make sure user is tracing the module with correct inputs with respect to the assumptions we made during first tracing. The way I do is that I create new graph module type with modified call method. And the runtime assertions happen under torchdynamo.disable so that it is just run in eager directly. The reason is we don't this to be traced part of the graph.
3) Both ep.module and capture_pre_autograd now returns _UnliftedGraphModule.
Differential Revision: [D51078056](https://our.internmc.facebook.com/intern/diff/D51078056)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110222
Approved by: https://github.com/zhxchen17
Custom classes that are serialized with pytree are serialized by default with `f”{class.__module__}.{class.__name__}”`. This is a dependency from our serialized program directly into the outer Python environment. If a user moves the class to a different directory, the serialized program will be unable to be loaded. So, we will require users to pass in an FQN if they want to serialize their custom treespec type.
Differential Revision: [D50886366](https://our.internmc.facebook.com/intern/diff/D50886366)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112428
Approved by: https://github.com/suo
Fixes https://github.com/pytorch/pytorch/pull/102577#issuecomment-1650905536
Serializing to json is more stable, and renamed the API:
```
# Takes in a treespec and returns the serialized treespec as a string. Also optionally takes in a protocol version number.
def treespec_dumps(treespec: TreeSpec, protocol: Optional[int] = None) -> str:
# Takes in a serialized treespec and outputs a TreeSpec
def treespec_loads(data: str) -> TreeSpec:
```
If users want to register their own serialization format for a given pytree, they can go through the `_register_treespec_serializer` API which optionally takes in a `getstate` and `setstate` function.
```
_register_treespec_serializer(type_, *, getstate, setstate)
# Takes in the context, and outputs a json-dumpable context
def getstate(context: Context) -> DumpableContext:
# Takes in a json-dumpable context, and reconstructs the original context
def setstate(dumpable_context: DumpableContext) -> Context:
```
We will serialize to the following dataclass, and then json.dump this it to string.
```
class TreeSpec
type: Optional[str] # a string name of the type. null for the case of a LeafSpec
context: Optional[Any] # optional, a json dumpable format of the context
children_specs: List[TreeSpec],
}
```
If no getstate/setstate function is registered, we will by default serialize the context using `json.dumps/loads`. We will also serialize the type through `f"{typ.__module__}.{typ.__name__}"`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106116
Approved by: https://github.com/zou3519
In this pr, we allow users to register a customized flatten/unflatten/serialization/deserialization for a dataclass. We provide some default implementation for flatten/unflatten. We could implement a decorator based on it when needed.
## Motivation:
HuggingFace and many internal models return dataclass output and torch.export wants to maintain the invariant that export result (i.e. exported_program) has the same calling convention and result as the original callable.
This is not supported in export yet: we cannot recover the original dataclass from flattened output produced by the underlying graph module (produced by dynamo and processed further by aot_export). We need to have a place to store the metadata of the dataclass so that we can re-construct it. To avoid adding hacky code in export and allow princinpled extensibility, we think extending pytree may be a good option.
## Implementation:
@zou3519 mentioned https://github.com/pytorch/pytorch/pull/93214/files and [jax-2371](https://github.com/google/jax/issues/2371#issuecomment-805361566), which suggests that it's not a good idea to make dataclass a default pytree node but it could be good to provide a default implementation for dataclass. Since currently, this seems to be an export-only feature, we added this extension point in export.
We also add "return_none_fields" flag to control whether none fields are returned after flattening, which is expected to be False in produce_matching of dynamo.export.
Also added some tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106160
Approved by: https://github.com/zhxchen17
