[llvm] [TTI][WebAssembly] Pairwise reduction expansion (PR #93948)

[Petr Penzin via llvm-commits]

ppenzin wrote:

I was hoping we can discuss this in Wasm SIMD subgroup before merging.

@yolanda15 @jing-bao you might want to check if this change would have any effect on x86 patterns in V8.


https://github.com/llvm/llvm-project/pull/93948