This PR relands #95942, which was reverted in #96332 due to link
failures. It fixes the issue by updating CMake dependencies. The bazel
support, originally introduced in #96334, is also included in this PR.
---------
Co-authored-by: Keith Smiley <keithbsmiley@gmail.com>
This PR implements a MVP version of an MLIR lowering pipeline to SPIR-V.
The goal of adding this pipeline is to have a better test coverage of
SPIR-V compilation upstream, and enable writing simple kernels by hand.
The dialects supported in this version include `arith`, `vector` (only
1-D vectors with size 2,3,4,8 or 16), `scf`, `ub`, `index`, `func` and
`math`. New test cases for the pass are also included in this PR.
**Relevant links**
- [Open MLIR Meeting - YouTube
Video](https://www.youtube.com/watch?v=csWPOQfgLMo)
- [Discussion on LLVM
Forum](https://discourse.llvm.org/t/open-mlir-meeting-12-14-2023-discussion-on-improving-handling-of-unit-dimensions-in-the-vector-dialect/75683)
**Future plans**
- Add conversion patterns for other dialects, e.g. `gpu`, `tensor`, etc.
- Include vector transformation to unroll vectors to 1-D, and handle
those with unsupported sizes.
- Implement multiple-return. SPIR-V does not support multiple return
values since a `spirv.func` can only return zero or one values. It might
be possible to wrap the return values in a `spirv.struct`.
- Add a conversion for `scf.parallel`.
