[Mlir-commits] [mlir] [mlir][vector] Address linearization comments (post commit) (PR #138075)

[Andrzej Warzyński]

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@@ -447,18 +444,22 @@ struct LinearizeVectorSplat final
 
 } // namespace
 
-/// Return true if the operation `op` does not support scalable vectors and
-/// has at least 1 scalable vector result. These ops should all eventually
-/// support scalable vectors, and this function should be removed.
+/// Some operations currently will not be linearized if they have scalable
+/// vector results, although support should be added in the future. This
+/// function returns true if `op` is such an operation.
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banach-space wrote:

The actual rationale comes from the fact that `vector.shuffle` does not support scalable vectors: https://github.com/llvm/llvm-project/blob/0009a1783490a8ff69251a0ec7df1891a427cfb0/mlir/include/mlir/Dialect/Vector/IR/VectorOps.td#L430-L431

So, if linearising a particular Op requires `vector.shuffle`, scalable vectors cannot be supported. This would imply that none of these supports scalable vectors: https://github.com/llvm/llvm-project/blob/0009a1783490a8ff69251a0ec7df1891a427cfb0/mlir/lib/Dialect/Vector/Transforms/VectorLinearize.cpp#L516-L522

Could you update these comments accordingly? Also, 
> Some operations currently will not be linearized if they have scalable vector results

is there an example where non-scalable result (with some operands are scalable) makes an operation "linearizable"?

https://github.com/llvm/llvm-project/pull/138075