[llvm] [LowerTypeTests] Generate fshr for rotate pattern (PR #141735)

[Peter Collingbourne via llvm-commits]

https://github.com/pcc approved this pull request.

Thanks. I tested your change on a large internal binary built with CFI. It makes the binary larger by about 0.5% but I think that may just be due to the inliner activating more often because the check has fewer LLVM instructions (I didn't spot any issues in the generated code).

I also have a change on top of this one to replace zext(ptrtoint to i8) to i64 with just ptrtoint to i64 which seems to fix the #141326 codegen problems entirely. I'll upload it once this change is submitted because I don't think I can upload a stack that includes someone else's change.

https://github.com/llvm/llvm-project/pull/141735