For Itanium®-based applications, the -ivdep_parallel option indicates there is absolutely no loop-carried memory dependency in the loop where IVDEP directive is specified. This technique is useful for some sparse matrix applications.
For example, the following loop requires -ivdep_parallel in addition to the directive IVDEP to ensure there is no loop-carried dependency for the store into a().
a(b(j)) = a(b(j))+1
See also Vectorization Support.