Allows pack propagation through non-elementwise generics as long as all
tiled dimensions have parallel iterator types and are only indexed with
affine dim expressions by any of the operands.
This enables unpack propagation cases where the result type is different
from the current unpack destination tensor and thus motivates a similar
helper as the for pack for creating a destination tensor based on
pack information.
Outer dim permutations are allowed to permute reduction dims, however
remains unsupported for non-affine dim indexing map results.
Additionally ops with gather semantics now explicitly prohibit propagation.
Pack/unpack propagation through reductions may not always be beneficial
so user control over propagation decisions is made available through
a control function similar to the one for fusion.
Differential Revision: https://reviews.llvm.org/D147508
It introduces a pattern that swaps `linalg.generic + tensor.pack` to
`tensor.pack + linalg.generic`. It requires all the iteration types
being parallel; the indexing map of output operand is identiy. They can
all be relaxed in the future.
The user can decide whether the propagation should be applied or not by
passing a control function.
Reviewed By: mravishankar
Differential Revision: https://reviews.llvm.org/D138882
