[llvm] [GlobalISel] Handle div-by-pow2 (PR #83155)

[Shilei Tian via llvm-commits]

shiltian wrote:

After taking the advices, the code generated from GlobalISel was not changed for the case above. Need to figure out where they come from, especially the compare instruction.

https://github.com/llvm/llvm-project/pull/83155