[llvm] [ValueTracking] Compute known bits from recursive select/phi (PR #113707)

[via llvm-commits]

goldsteinn wrote:

This looks fine although I have two notes.

1) since we are sure to be breaking the recursion here we can probably do a full depth computeKnownBits below.

2) it would be nice if we could also use the selects compare context.

https://github.com/llvm/llvm-project/pull/113707