- argument name 'isLastOutput' in comment does not match parameter name
'hasOutput'.
- override is redundant since the function is already declared 'final'.
This patch introduces the lowering for xfer ops masked with `vector.mask`.
Vector reductions are not lowered yet because new LLVM intrinsics are needed
in the LLVM dialect.
Reviewed By: nicolasvasilache
Differential Revision: https://reviews.llvm.org/D136741