/sys$common/syshlp/helplib.hlb MACRO, /MIGRATION, Compiler Directives, .BRANCH LIKELY, Example  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  MOVL (R0),R1
  .BRANCH_LIKELY
  BNEQ    10$
    .
    .
    .
  10$

      The compiler will move the code between the BNEQ instruction
      and label 10$ to the end of the module, and change the BNEQ 10$
      to a BEQL to the moved code. It will then continue immediately
      following the BEQL instruction with generation of the code
      starting at label 10$. This will eliminate the delay that
      occurs on Alpha systems for a mispredicted branch.