[Unity][CUTLASS] Fix circular import bug in relax cutlass backend

[digital-nomad-cheng]

There exists circular import bug in tvm/python/tvm/relax/backend/contrib/cutlass.py

Code to reproduce:

from tvm.contrib.cutlass import (
    has_cutlass,
    num_cutlass_partitions,
    finalize_modules
)

Error:

File "/home/work/tmp/test.py", line 1, in <module>
    from tvm.contrib.cutlass import (
  File "/home/tvm/python/tvm/contrib/cutlass/__init__.py", line 18, in <module>
    from .build import has_cutlass, num_cutlass_partitions, finalize_modules, finalize_modules_vm
  File "/home/tvm/python/tvm/contrib/cutlass/build.py", line 28, in <module>
    from tvm import relax, relay, runtime
  File "/home/tvm/python/tvm/relax/__init__.py", line 90, in <module>
    from . import backend
  File "/home/tvm/python/tvm/relax/backend/__init__.py", line 19, in <module>
    from . import contrib
  File "/home/tvm/python/tvm/relax/backend/contrib/__init__.py", line 20, in <module>
    from .cutlass import partition_for_cutlass
  File "/home/tvm/python/tvm/relax/backend/contrib/cutlass.py", line 24, in <module>
    from tvm.contrib.cutlass.build import is_shape_valid_for_cutlass_matmul
ImportError: cannot import name 'is_shape_valid_for_cutlass_matmul' from partially initialized module 'tvm.contrib.cutlass.build' (most likely due to a circular import) (/home/tvm/python/tvm/contrib/cutlass/build.py)

[tvm-bot]

Thanks for contributing to TVM! Please refer to the contributing guidelines https://tvm.apache.org/docs/contribute/ for useful information and tips. Please request code reviews from Reviewers by @-ing them in a comment.

• cc @quic-sanirudh _{See #10317 for details}

_{Generated by tvm-bot}

[masahi]

I think it is better to remove from .cutlass import partition_for_cutlass from backend/contrib/__init__.py since doing import relax shouldn't cause contrib/cutlass/build.py to depend on contrib/cutlass.py. cc @yelite

[digital-nomad-cheng]

Import removed from __init__

[masahi]

You can remove this file now that it is not used at all.

[digital-nomad-cheng]

Thanks for the feedback, file removed.