[clang] [llvm] [AMDGPU] Match bitsin(typeof(x)) - ctpop(x) to s_bcnt0_i32 (PR #164847)

[Jay Foad via llvm-commits]

https://github.com/jayfoad approved this pull request.

Really the benefit still seems marginal, but I guess it's not doing any harm.

> If you have reason to believe that the other pattern will also match, I'll add it, too. Would you like me to do that?

Yes please but it could be a separate PR with its own test coverage.

https://github.com/llvm/llvm-project/pull/164847