Portable branch prediction hints

Question

Is there any portable way of doing branch prediction hints? Consider the following example:

  if (unlikely_condition) {
    /* ..A.. */
  } else {
    /* ..B         


        

Answer 1

C++20 offers likely and unlikely attributes

Allow the compiler to optimize for the case where paths of execution including that statement are more or less likely than any alternative path of execution that does not include such a statement