[llvm] [CmpInstAnalysis] Decompose icmp eq (and x, C) C2 (PR #136367)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Historically the purpose of decomposeBitTestICmp() was to decompose plain icmps into and+icmp form, but I don't see a reason not to support the and+icmp form directly for cases where the distinction does not matter.

https://github.com/llvm/llvm-project/pull/136367