[Reland] Adds an aten::_ops namespace with unambiguous function names (#59018)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59018
Fixes #58044.
This PR:
- adds `ATEN_FN(op)` and `ATEN_FN2(op, overload)` macros that resolve to
an non-overloaded function in aten::_ops that calls the desired operator
(without default arguments).
The motivation for this is two-fold:
1) Using aten operators with templates is hard if the operator is
overloaded (e.g. add.Tensor and add.Scalar).
2) Method-only operators require special handling; pointers-to-method
are different from function pointers. `ATEN_FN2(add_, Tensor)` returns
a function instead of a method.
There is some interesting behavior for out= operations.
`ATEN_FN2(sin, "out")` gives a function that is *faithful* to the schema;
that is, the order of arguments is exactly what it looks like in the
schema. This makes it so that you can directly register
`ATEN_FN2(sin,"out")` (or a function wrapping it using the same signature)
as an override for a DispatchKey.
Test Plan:
- New tests that ATEN_FN2 works on function and method-only operators
- New test that ATEN_FN works
- New test that ATEN_FN macro returns a "faithful" function.
Codegen output:
Operators.h and Operators.cpp are both here:
https://gist.github.com/zou3519/c2c6a900410b571f0d7d127019ca5175
Reviewed By: bdhirsh
Differential Revision: D28721206
Pulled By: zou3519
fbshipit-source-id: a070017f98e8f4038cb0c64be315eef45d264217
