[llvm] [DemandedBits] Add div/rem support (PR #148853)

[Nikita Popov via llvm-commits]

nikic wrote:

@karouzakisp Here are the proofs: https://alive2.llvm.org/ce/z/hYWDwZ

This shows that urem, udiv and srem handling is correct and sdiv handling is incorrect. Please try to provide this form of proof for all demanded bits transform.

Note that handling urem and udiv for power of two divisor is actually useless because these will be converted to and / lshr. Only handling srem and sdiv is useful.

https://github.com/llvm/llvm-project/pull/148853