[llvm] [SLP] Add vectorization support for [u|s]cmp (PR #106747)

[Nikita Popov via llvm-commits]

nikic wrote:

This looks technically fine, but I think we need to improve the vector legalization before enabling this. We currently scalarize too much, e.g. take a look at https://llvm.godbolt.org/z/Er1GYv8E4. The second version is a good match for the cost estimate, the actual expansion, not so much...

https://github.com/llvm/llvm-project/pull/106747