可能/不太可能而不是if / else

Question

I replaced one occurrence of if/else with likely/unlikely which given me some improvement in performance as this executes many times. Now I would like to change all the occurrences of if/else with likely/unlikely . I use this code on only one target/OS.

Does this have any drawbacks to replace all if/else 's ?

Answer 1

As likely and unlikely usually are macros defined in some library and expanding to some __buildin... -commands, the only drawback you can expect is, that this might be harder to read.

Edit: But please - use it only in that cases, where you really expect a condition to be more likely than the alternative!

If some platform / library does not implement likely and unlikely or the implementation is wrong, you can easily #define it empty by yourself.