add slice/select/diagonal_scatter variants as primitive ops (#64430)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64430
The functionalization pass needs `{view}_scatter` versions of the slice/select/diagonal ops in order to correctly propagate mutations from a view to its base. On top of that, the implementations need to be primitive w.r.t. autograd, because they look something like `...slice().copy_()`, and the functionalization pass can't use views + mutations inside of it's own alias-removal machinery!
I added some basic tests that I tried to base off of existing tests for views (particularly around testing the derivative formulas), but I'm wondering if I should add something more comprehensive.
Also, as_strided fits into this category - the functionalization pass will need an `as_strided_scatter` op that's primitive w.r.t. autograd. I didn't add it for now, because it'll involve duplicating a bunch of logic from the current `as_strided_backward()` function, and also writing a derivative formula that I wasn't sure how to write :)
Test Plan: Imported from OSS
Reviewed By: albanD
Differential Revision: D31942092
Pulled By: bdhirsh
fbshipit-source-id: c702a57c2748a7c771c14e4bcc3e996b48fcc4c8
