unw\_dyn\_region\_info\_t:

        - insn_count can be negative to indicate that the region is
          at the end of the procedure; in such a case, the negated
          insn_count value specifies the length of the final region
          in number of instructions.  There must be at most one region
          with a negative insn_count and only the last region in a
          procedure's region list may be negative.  Furthermore, both
          di->start\_ip and di->end\_ip must be valid.