[llvm] [IndVars] Support decrementing counters in LFTR (PR #225619)

[Nikita Popov via llvm-commits]

nikic wrote:

I'm generally apprehensive about any extensions to LFTR, because this is a transform that can just as easily be a regression as an improvement, and it does not try particularly hard to distinguish those cases.

It seems like the motivation for this is some kind of backend issue -- in that case, wouldn't it be the responsibility of LSR to deal with it?

https://github.com/llvm/llvm-project/pull/225619