Two changes:
- no more "verifyPasses" constructor arg for PassManager
- OpPassManager defaults to requiring explicit "nest" calls when created
via the C++ API. The behavior upstream for mlir-opt still obeys the
"implicit" mode, so I just slapped that onto all our pass managers.
I pinged https://reviews.llvm.org/D90671 to get a signal for whether we
are expected to migrate to explicit mode. If so, I'll do that too later.
Other than the dialect definitions (which will live in standard Dialect/
subdirectory), the goal here is to keep RefBackend-related code nested
in {include/npcomp,lib,test}/RefBackend.
This unblocks backend progress while the PyTorch frontend work is coming
online. Hopefully we can delete this soon.
See tools/mnist-playground/README.md for more context on what this tool
is for, next steps, and current status.