[llvm] [IPO] Added attributor for identifying invariant loads (PR #141800)

[Krzysztof Drewniak via llvm-commits]

krzysz00 wrote:

> The main problem is invariant load doesn't do anything on memcpy or other memory intrinsics

That feels ... fixable? (Especially since MachineMemOperand has an `invariant` field)

But that's probably a low-priority eventually sort of thing

https://github.com/llvm/llvm-project/pull/141800