add test_tensorexpr.py (#35776)
Summary:
Adding `test_tensorexpr.py` to our CI. There's a few complications: the first one is that we now always run `SimpleIREVal` as a part of simplifier, so the counts will always be greater than one. We can potentially invest some effort to differentiate between a real codegen call to `SimpleIREval` and calls in simplifier, but it's probably not that important and the second change to turn not being able to retrieve a counter into a default value of 0 since the test are structured to test for either an llvm or simpleireval backends, so it only seems appropriate to not fail the test too early.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35776
Differential Revision: D20799333
Pulled By: Krovatkin
fbshipit-source-id: 2a94ff98e647180c6e6aea141a411c3376c509f9
