[llvm] [FuncSpec] Consider literal constants of recursive functions (PR #111162)

[Hari Limaye via llvm-commits]

hazzlim wrote:

> Can we remove promoteConstantStackValues() ? Do you see any regressions doing so? As far as I remember that was a hack for exchange2_r, since fortran passes arguments by reference.

I think that provided both #111163 and this PR get in, we would be able to remove `promoteConstantStackValues()` without causing any regressions. So that would be the goal following these changes, but it does rely on Argument Promotion being run before IPSCCP. For this reason I was intending to put this up as a separate patch - however I could merge it into this change if that seems appropriate.

https://github.com/llvm/llvm-project/pull/111162