[llvm] [DAGCombine] Improve bswap lowering for machines that support bit rotates (PR #164848)

[Jay Foad via llvm-commits]

jayfoad wrote:

> Still on mobile - but the codegen still doesn't look right - are the rotates the right way around?

Well spotted - no they're not.

https://github.com/llvm/llvm-project/pull/164848