This patch adds a mixin for TileToForallOp to
_structured_transform_ops_ext.py with syntactic sugar for construction
such ops. First, the types of the results are made optional and filled
with common default values if omitted. Second, for num_threads and
tile_sizes, the three possible forms (static, dynamic, or packed), can
now all be given through the same respective argument, which gets
dispatched to the correct form-specific argument automatically.
Reviewed By: nicolasvasilache, ftynse
Differential Revision: https://reviews.llvm.org/D155090
be6e9df11f