Description

   See the description of the .BRANCH_LIKELY directive for the
   assumptions used by the compiler when predicting branches.

   On OpenVMS I64 systems, when .BRANCH_UNLIKELY precedes a
   conditional backwards branch, the compiler will use the
   appropriate branch prediction flags on the generated Itanium
   instruction.

   .BRANCH_UNLIKELY has no effect if it precedes a conditional
   forwards branch.