Yes and no. I say yes because C and C++ both have likely() and unlikely() functions (well, technically It's part of a compiler extension rather than the langua

Yes and no. I say yes because C and C++ both have likely() and unlikely() functions (well, technically It's part of a compiler extension rather than the language), which you wrap around the condition inside your if() statement like so: for(i=10000; i<100000; i++) { if(unlikely(isPrime(i))) { // do something special } else { // do something boring } } I say no because most modern compilers simply ignore the functions. Compilers have become so sophisticated over the years that developers trying to help them along or optimize often make things worse, whether that's by getting in the compiler's way or just writing code that's harder to read and debug. I say no (or at least probably not) to your second questions as well. No language I know if implements anything as sophisticated as a specification for regular intervals of branch switching. Many modern compilers have sophisticated branch prediction routines which can detect simple regular intervals like you describe. To develop such a specification would optimize the branch prediction by a tiny margin which would be absolutely dwarfed by the overhead of learning the syntax for the specification, not messing it up, debugging it if you do mess it up, communicating the decision to other team members, and all of the other real-world stuff that gets in the way. Computers are faster than ever and branch prediction algorithms are smarter than ever. Yes, you could help it along in theory but the portion of applications which really require you to do so is dwindling all the time.