Reimplement per-operator selective build (#39401)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39401
This uses the technique proposed by smessmer in D16451848 to selectively
register operators without codegen. See the Note inside for more
details.
This PR has feature parity with the old selective build apparatus:
it can whitelist schema def()s, impl()s, and on a per dispatch key
basis. It has expanded dispatch key whitelisting, whereas previously
manually written registrations were not whitelisted at all. (This
means we may be dropping dispatch keys where we weren't previously!)
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: pbelevich
Differential Revision: D21905593
Pulled By: ezyang
fbshipit-source-id: d4870f800c66be5ce57ec173c9b6e14a52c4a48b
