[llvm] [ConstantFolding] Add folding for [de]interleave2, insert and extract (PR #141301)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> These make sense to have, but I'm wondering if you were seeing any cases where we were using fixed length versions of these intrinsics. From my understanding these are only really used for scalable vectors in the loop vectorizer etc.

The fixed versions of these intrinsics are generated by vectorizers (at least they exist in fuzzer-generated cases).


https://github.com/llvm/llvm-project/pull/141301