[cmovq]

PGO is not a silver bullet. If you've identified a problem that can be solved by a simple static hint you should do that. I agree littering your code with likely/unlikely will probably make things worse, so it's best to save them for those exceptional cases where you know it will make an improvement.

[Kranar]

It's not a silver bullet but PGO does subsume these hints. Consider what do you do if PGO conflicts with your static hints? My hypothesis is that in that case the static hint is most likely incorrect and contributing to slower code.

So either you aren't using PGO at all, which is fine if squeezing out these kinds of optimizations isn't that important to you, but then what's the point having these static hints?

Or you are using PGO, in which case there's no point in having these static hints because PGO will identify the likely and unlikely scenarios on your behalf. If PGO doesn't identify likely and unlikely branches, then the reason is because your profile isn't representative of how your program will actually be run in production, but in that case the solution is to provide a more representative profile instead of using [[likely]] and [[unlikely]].