[llvm] Revert "Redesign Straight-Line Strength Reduction (SLSR) (#162930)" (PR #169546)

[Fei Peng via llvm-commits]

fiigii wrote:

@lialan FYI, this bug still exists even if reverting my change. The new SLSR is more powerful and can find more opportunities, so it amplifies the problem in more scenarios. See an example at https://github.com/llvm/llvm-project/pull/162930#issuecomment-3578100592 

https://github.com/llvm/llvm-project/pull/169546