[llvm] [SCEV][LV] Invalidate LCSSA exit phis more thoroughly (PR #69909)

[Florian Hahn via llvm-commits]

fhahn wrote:

> > Hey @nikic, is this patch in scope to fix #69744 as well? I think this still repros on your branch.
> 
> That’s something I’d like to check in the next few days

Ok looks unrelated to this PR. (Planning to  take a look at this one tomorrow or on Monday)

https://github.com/llvm/llvm-project/pull/69909