[llvm] [PredicateInfo] Support existing `PredicateType` by adding `PredicatePHI` when needing introduction of phi nodes (PR #151132)

[Nikita Popov via llvm-commits]

nikic wrote:

It looks like the store in `5:` still uses `%0`, without a phi. We only have the phi in `common.ret`, where the value is not actually used...

https://github.com/llvm/llvm-project/pull/151132