[llvm] [LV] Simplify live-out extraction for first-order recurrence phis when tail folding (PR #176108)

[Mel Chen via llvm-commits]

Mel-Chen wrote:

> Overall looks like a nice simplification! It would be great if you could rebase the PR, then I can run some quick sanity checks.
> 
> > Reverse ping for a rebase and other reviews? It would be nice to get this bit of code removed before #191298
> 
> I think it doesn't make a big difference if we remove or move it first.

Sure, rebased.

https://github.com/llvm/llvm-project/pull/176108