Refactor dispatcher and native to use Signature structure. (#45990)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45990
In #45890 we introduced the concept of a CppSignature, which bundled
up all of the information necessary to declare a C++ signature for
the cpp API. This PR introduces analogous concepts for dispatcher
and native: DispatcherSignature and NativeSignature.
The three interfaces are not particularly well coupled right now,
but they do have some duck typing coincidences:
- defn() which renders the C++ definition "bool f(int x)"
- decl() which renders the C++ declaration "bool f(int x = 2)"
- type() which renders the C++ function type "bool(int)"
Maybe at some point we'll introduce a Protocol, or a supertype.
Many other methods (like arguments()) have varying types. These
signatures also have some helper methods that forward back to real
implementations in the api modules. Something to think about is
whether or not we should attempt to reduce boilerplate here or
not; I'm not too sure about it yet.
The net effect is we get to reduce the number of variables we
have to explicitly write out in the codegen, since now these are all
bundled together into a signature. Something extra special happens
in BackendSelect, where we now dynamically select between dispatcher_sig
and native_sig as "how" the backend select is implemented.
A little bit of extra cleanup:
- Some places where we previously advertised Sequence, we now advertise
a more informative Tuple.
- defn() may take an optional positional parameter overriding the entire
name, or a kwarg-only prefix parameter to just add a prefix to the
name.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: smessmer
Differential Revision: D24223100
Pulled By: ezyang
fbshipit-source-id: f985eced08af4a60ba9641d125d0f260f8cda9eb
