[llvm] [FunctionAttrs] Handle alias-preserving intrinsic calls correctly (PR #68453)

[Krzysztof Drewniak via llvm-commits]

krzysz00 wrote:

Huh

In which case, I'm confused by why the function in ValueTracking mentions `WithoutCapturing`.

And by what the semantics of `nocapture` are in general - my sense of it was that a capture involves storing a pointer somewhere such that it might be used after its SSA value is out of scope, and so nocapture indicates a lack of that behavior.

It's entirely possible that I'll want to go fix up `make.buffer.rsrc` and then also commit this as a precision improvement.

https://github.com/llvm/llvm-project/pull/68453