The pass is mostly borrowed from the BufferizeAnyLinalgOp pass in mlir
upstream with some minor changes. At a high level, it's a naive partial
bufferization pass which allocate new buffers for all the output
tensors. The initial value of an output buffer is copied from the
original buffer if there are uses of the original value.
One difference from linalg bufferization pass is the way to tell if
the loop body uses the init value of output operand. For TMTensor ops,
it differs from op to op because the payload region doesn't represent
the entire loop body.
There are cases where the op may update the same indices multiple
times. In this context, we can not parallelize updates. Instead,
we have to execute them sequentially. Adding a boolean attribute
to control the behavior.
Also adding test cases for invalid IR.
This is intended to explore support for non-structured ops that can't
be modeled by Linalg dialect. `tm_tensor.scan` and `tm_tensor.scatter`
are added as the first such ops. The dialect should aim to be
upstreamed in the future.