[llvm] [VectorUtils] Trivially vectorize ldexp, [l]lround (PR #145545)

[David Green via llvm-commits]

davemgreen wrote:

They should all have an invalid cost if there is no lowering for them, preventing vectorization. https://godbolt.org/z/78hT1j98G
Maybe one of them isn't getting an invalid cost for some reason?

https://github.com/llvm/llvm-project/pull/145545