[llvm] [PredicateInfo] Don't use depth first walk (NFCI) (PR #145016)

[Nikita Popov via llvm-commits]

nikic wrote:

> IIRC the orders in `OpsToRename` and `OperandInfo.Infos` don't matter, as we will perform a stable sort later on `OrderedUses`, right?

They don't matter in the sense that it's not important for correctness. I believe the order of the inserted ssa.copy instructions *can* change as a result, but the instructions themselves will be the same.

https://github.com/llvm/llvm-project/pull/145016