[llvm] Reland "[LTO] Run Argument Promotion before IPSCCP" (PR #111853)

[Hari Limaye via llvm-commits]

hazzlim wrote:

> In any case, this change needs a PhaseOrdering test.

Thanks for pointing this out - I've added a PhaseOrdering test.

> I see that there is a PostOrderFunctionAttrsPass run shortly after these passes -- would it be feasible to move it earlier rather than running twice?

Good point - I've moved the `PostOrderFunctionAttrsPass` from after IPSCCP to before, and this doesn't seem to break any PhaseOrdering tests or cause any regressions in SPEC2017. 

https://github.com/llvm/llvm-project/pull/111853