Improve `generate_opcheck_tests`, add opcheck utility (#107597)
Summary:
This PR improves `generate_opcheck_tests`:
- We shouldn't run automated testing through operators called in
torch.jit.trace / torch.jit.script
- I improved the error message and added a guide on what to do if one of the
tests fail.
- While dogfooding this, I realize I wanted a way to reproduce the failure
without using the test suite. If you pass `PYTORCH_OPCHECK_PRINT_REPRO`, it
will now print a minimal repro on failure. This involves serializing some
tensors to disk.
- The minimal repro includes a call to a new API called `opcheck`.
The opcheck utility runs the same checks as the tests generated
by `generate_opcheck_tests`. It doesn't have a lot of knobs on it for
simplicity. The general workflow is: if an autogenerated test fails, then the
user may find it easier to reproduce the failure without the test suite by
using opcheck
Test Plan: - new tests
Differential Revision: D48485013
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107597
Approved by: https://github.com/ezyang
