pytorch

062ac6b4 - Bring up new-style registration API as wrapper around old-style (#33205)

Bring up new-style registration API as wrapper around old-style (#33205) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/33205 A number of important use-cases are implemented: - def(schema): defines a schema, with no implementation (alias inferred from schema, by default) - def(schema, fn_ptr): registers fn_ptr as a catch-all kernel for the operation - def(schema, lambda): registers lambda as a catch-all kernel for the operation - def(schema, torch::dispatch(dispatch_key, fn)), and def(schema, torch::dispatch(device_type, fn)): registers the function to only be executed when dispatch_key/device_type is selected for use - def(schema, TORCH_OPTIMIZED_FN(fn)): registers the function as unboxed only, using the inline syntax All of our code generated registrations in ATen are switched to the new API. Some aspects of the API which are not fully implemented: - It's still not valid to omit the schema when registering a function pointer, due to #32549 - Although it's possible to take advantage of top-level namespaces ala torch::import("aten"), we don't use it because this results in worse code (as we have to cat everything back together). This is not an essential problem, we just need the internals to be less stupid. There are some aspects of the API which don't semantically make sense, but I chose not to fix them in this PR: - For some reason, TORCH_OPTIMIZED_FN uses the *runtime* wrapper to do wrapping, rather than the compile time one which inlines the function in. This means that there isn't any reason we should be passing in the function pointer as a template argument; a regular old argument ought to have worked fine. This is seemingly consistent with the current API though; needs further investigation. - There's no reason to optional<DispatchKey>, DispatchKey would work just fine (use DispatchKey::Undefined for the nullopt case) In the long term, we should swap the wrapper around: the new-style API has the real implementation, and the old-style API is backwards compatibility. However, this implies a lot of internal refactoring, so I decided to short circuit around it to get this in faster Ancillary changes: - I stopped moving optional<DispatchKey>, it's literally just two words, pass it by value please. - Needed to add a & qualified version of RegisterOps::op, since I'm storing RegisterOps as a member inside the new style Namespace and I cannot conveniently get a rvalue reference to it in that situation. (BTW, register_ = std::move(register_) really doesn't work, don't try it!) Signed-off-by: Edward Z. Yang <ezyang@fb.com> Test Plan: Imported from OSS Differential Revision: D19856626 Pulled By: ezyang fbshipit-source-id: 104de24b33fdfdde9447c104853479b305cbca9a