[mlir][mesh] adding shard-size control (#98145)

- Replacing `#mesh.sharding` attribute with operation `mesh.sharding`
- extended semantics now allow providing optional `halo_sizes` and
`sharded_dims_sizes`
- internally a sharding is represented as a non-IR class
`mesh::MeshSharding`

What previously was
```mlir
%sharded0 = mesh.shard %arg0 <@mesh0, [[0]]> : tensor<4x8xf32>
%sharded1 = mesh.shard %arg1 <@mesh0, [[0]]> annotate_for_users : tensor<16x8xf32>
```
is now
```mlir
%sharding = mesh.sharding @mesh0, [[0]] : !mesh.sharding
%0 = mesh.shard %arg0 to %sharding : tensor<4x8xf32>
%1 = mesh.shard %arg1 to %sharding annotate_for_users : tensor<16x8xf32>
```
and allows additional annotations to control the shard sizes:
```mlir
mesh.mesh @mesh0 (shape = 4)
%sharding0 = mesh.sharding @mesh0, [[0]] halo_sizes = [1, 2] : !mesh.sharding
%0 = mesh.shard %arg0 to %sharding0 : tensor<4x8xf32>
%sharding1 = mesh.sharding @mesh0, [[0]] sharded_dims_sizes = [3, 5, 5, 3] : !mesh.sharding
%1 = mesh.shard %arg1 to %sharding1 annotate_for_users : tensor<16x8xf32>
```
- `mesh.shard` op accepts additional optional attribute `force`, useful
for halo updates
- Some initial spmdization support for the new semantics
- Support for `tensor.empty` reacting on `sharded_dims_sizes` and
`halo_sizes` in the sharding
- New collective operation `mesh.update_halo` as a spmdized target for
shardings with `halo_sizes`

@sogartar @yaochengji

0 files changed, 0 insertions, 0 deletions