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

[Alan Li via llvm-commits]

lialan wrote:

> @lialan Thanks for reporting this issue. What conflicts do you mean? I did not see git conflicts.

Doing simple `git revert` will have some conflicts which I had to fix. and them probably there were some other updates on the lit tests. 

so just want you to help to double check if the revert is correct. 

I don't want to change too much, since I know you will have to re-submit in a bit.

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