[llvm-branch-commits] [TailCallElim] Add profile annotations to return value selects (PR #202518)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/202518

Tail call elimination in some cases can create selects on possible
return values conditioned on whether or not execution is currently in
what was a recursive call. That is equal to the probability with which
we recurse, which in turn can be computed from the block frequencies of
blocks that recurse and blocks that directly return.