Swizzling is no longer implemented as a separate pass. It is instead
done in a specialized constructor of SharedEncodingAttr, and tested via
google tests instead of triton-opt + filecheck.
In the future we may want to implement it as a pass again once we have
an additional dialect between TritonGPU and LLVM.
## Features
- Allow taking a block of tensor slice, as long as each dimension is
contiguous (unit stride).
- Fix some problems in `insert_slice_async`'s semantic.
- More general verification for ops that return shared layout encoding.
## Known Limitations
- `insert_slice_async` still uses the old semantic. May submit another
PR later to support similar semantic like `tensor.extract_slice`.
- No encoding verification for `tensor.extract_slice`.
- 3d tensor ops are broken.
- Strided accesses are not allowed.
- May cause a little performance slowdown since we are passing strides
as values but not constants (e.g., int).
It would be difficult to pass strides as attributes when we have control
flows. A block argument is possible to accept tensors with different
strides.
1. Rewrite code generation of insert_slice_async.
2. Correct the wrong index passed to extract_slice in pipeline.
3. Add a prologue in pipeline to wait for dangling cp.asyncs.
4. Move scf to cf conversion inside TritonGPUToLLVM because we need to
perform membar before scf to cf. It shouldn't be a technical limitation
and could be improved by a more general membar analysis.
5. Use an attribute to memoize the shared memory size and support
dynamic shared memory.
6. Prevent the combine pass to reorder insert_slice and extract_slice
across async_wait
Co-authored-by: Superjomn <yanchunwei@outlook.com>
This code in this branch assumes the `src` operand in
`insert_slice_async` always aliases the result, which shouldn't hold for
generally cases but is just a workaround to make the pipeline pass work.
I'm also working on the complete analysis in another
[branch](https://github.com/openai/triton-mlir/tree/keren/analyze-slice).
This PR both simplifies the layout conversion simplification algorithm, and also improves it to make it work with vectorized element-wise ops. The conversion optimizer still has a lot of room for improvements, and other PRs will address its limitations (ideally via some sort of explicit cost model)
