[llvm] [LV] Stengthen loop-invariance checks in isPredicatedInst (PR #140744)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Okay, the tests were faulty, and not covering the code: it is incredibly hard to cover all the code, but I've now verified that the tests do indeed cover each change, by reverting each individual change and checking.

https://github.com/llvm/llvm-project/pull/140744