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

[Patrick Simmons via cfe-commits]

linuxrocks123 wrote:

@jayfoad well, I don't see this increasing register pressure, so I want to keep the pattern.  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?

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