[llvm] [DominanceFrontier] make DominanceFrontierBase::find iterator deterministic (PR #69711)

[Florian Hahn via llvm-commits]

fhahn wrote:

Could you clarify what the problem is exactly? The description says it makes the `DominanceFrontierBase::find` iterator deterministic, but `find` returns an iterator to the map, not the set you are changing?

So IIUC the patch makes iterating over the set of nodes for a frontier deterministic. Overall I agree that making this deterministic is desirable, I am a bit curious why this issue hasn't shown up before with current in tree users, and if there's some way we can test this in upstream.

https://github.com/llvm/llvm-project/pull/69711