[TensorExpr] Redesign `Tensor` class. (#50995)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50995
This change makes 'Tensor' a thin wrapper over 'Buf' and 'Stmt', and
merges it with recently introduced 'CompoundTensor'. A statement for the
tensor is either passed directly to the Tensor constructor (akin to
'CompoundTensor'), or is built immediately in constructor.
LoopNest is no longer responsible for constructing statements from
tensors - it simply stitches already constructed statements contained in
Tensors. This has a side effect that now we cannot construct several
loopnests from the same tensors - we need to explicitly clone statements
if we want to do that. A special copy constructor was added to LoopNest
to make it more convenient (note: this only affects tests, we don't
usually create multiple loopnests in other places).
Test Plan: Imported from OSS
Reviewed By: bertmaher
Differential Revision: D26038223
Pulled By: ZolotukhinM
fbshipit-source-id: 27a2e5900437cfb0c151e8f89815edec53608e17
Author
Mikhail Zolotukhin
