We recently removed the singleton dimension level type (see the revision
https://reviews.llvm.org/D131002) since it was unimplemented but also
incomplete (properties were missing). This revision add singleton back as
extra dimension level type, together with properties ordered/not-ordered
and unique/not-unique. Even though still not lowered to actual code, this
provides a complete way of defining many more sparse storage schemes (in
the long run, we want to support even dimension level types and properties
using the additional extensions proposed in [Chou]).
Note that the current solution of using suffixes for the properties is not
ideal, but keeps the extension relatively simple with respect to parsing and
printing. Furthermore, it is rather consistent with the TACO implementation
which uses things like Compressed-Unique as well. Nevertheless, we probably
want to separate dimension level types from properties when we add more types
and properties.
Reviewed By: Peiming
Differential Revision: https://reviews.llvm.org/D132897
* Adds dialect registration, hand coded 'encoding' attribute and test.
* An MLIR CAPI tablegen backend for attributes does not exist, and this is a relatively complicated case. I opted to hand code it in a canonical way for now, which will provide a reasonable blueprint for building out the tablegen version in the future.
* Also added a (local) CMake function for declaring new CAPI tests, since it was getting repetitive/buggy.
Differential Revision: https://reviews.llvm.org/D102141
