Yes, unlikely()/likely() is a much better way to give the compiler hints about block linearization.
Here it is on godbolt: http://goo.gl/iPCiSy
Here it is on godbolt: http://goo.gl/iPCiSy
In practice, I'd be surprised if you can come up with a case where this makes a significant difference. If you are on a hot enough path for this to matter, on a modern processor you probably are running out of the even lower level decoded µop cache, which doesn't cache µops for branches that are not taken. If you aren't in this cache, your efforts are probably better spent making this happen.
Edit: ot's comment about how this affects the size of the parent function and whether it will be inlined is a good point, and might well make a measurable difference in the cases where it is true.