Sometimes consistency is desirable, as well as performance. Compilers are heuristic. They evolve and get better, but they can mess up, and it's not always a fun time to find out why the compiler made something that was performance sensitive suddenly do worse, intrinsics or not -- from things like a compiler upgrade, or the inlining heuristic changes because of some slight code change, or because it's Friday the 13th (especially when it's something horridly annoying like a solid %2-3 worse -- at least with %50 worse I can probably figure out where everything went horribly wrong without spending a whole afternoon on it). This is a point that's more general than intrinsics, but I think it's worth mentioning.
Sure, I can file bug reports in those cases, and I would attempt to if possible -- but it also doesn't meaningfully help any users who suddenly experience the problem. At some point I'd rather just write the core bit a few times and future proof myself (and this has certainly happened for me a non-zero amount of times -- but not many more than zero :)
Sure, I can file bug reports in those cases, and I would attempt to if possible -- but it also doesn't meaningfully help any users who suddenly experience the problem. At some point I'd rather just write the core bit a few times and future proof myself (and this has certainly happened for me a non-zero amount of times -- but not many more than zero :)