[llvm] [SCEV] Fix cache poisoning from depth-limited truncate expressions (PR #172234)

[Nikita Popov via llvm-commits]

nikic wrote:

I think the right way to fix the IndVarSimplify issue is to not assume the truncation is going to return a specific type. If it does not return an addrec, we can use a fallback implementation that truncates at the end instead of the start. That's less efficient but shouldn't really matter for this edge case.

https://github.com/llvm/llvm-project/pull/172234