title: __builtin_expect from GCC with probability
body: <p><code>__builtin_expect</code> from GCC  can be used by programmer to show which variants are expected to be very often and which are rare. But  <code>__builtin_expect</code> have only "true" and "false" (0% or 100% probability)</p>
  
  <p>For some big projects it is vary hard to get profile feedback (<code>-fprofile-arcs</code>), and sometimes programmer does know, what probability of branch he have in some point of program.</p>
  
  <p>It is possible to give a hint to compiler that a branch have probability >0% and &lt;100% ?</p>