[clang] [llvm] [CVP] Infer range return attribute (PR #99620)

[Nikita Popov via cfe-commits]

nikic wrote:

> Missing fold: https://alive2.llvm.org/ce/z/2rmc3h See [dtcxzyw/llvm-opt-benchmark#1342 (comment)](https://github.com/dtcxzyw/llvm-opt-benchmark/pull/1342#discussion_r1767033125)

In principle, I think this could be supported by making decomposeBitTestICmp detect that `ugt 255` means `& 256 == 1` together with information from computeConstantRange(). Not sure if it's worth it...

https://github.com/llvm/llvm-project/pull/99620