[llvm] Use (de)interleaving intrinsics for fixed-length vectors (PR #202583)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from a36610c9db6c05cccd6bed251f2b4df1730c1130...f920861b57e45466368b9248480d9f7b749092fe: https://github.com/llvm/llvm-project/actions/runs/27318915374/artifacts/7554464807

https://github.com/llvm/llvm-project/pull/202583