* loop.c (strength_reduce): Call check_ext_dependant_givs.
        Properly extend the biv initial value for the giv.
        (record_biv): Zero ext_dependant.
        (record_giv): New argument ext_val.  Update all callers.
        (general_induction_var): Likewise.
        (consec_sets_giv): Likewise.
        (simplify_giv_expr): Likewise.  Fill in ext_val if we find
        a sign-extend, zero-extend, or truncate.
        (combine_givs_p): Make sure modes are compatible.
        (check_ext_dependant_givs): New.
        (extend_value_for_giv): New.
        * loop.h (struct induction): Add ext_dependant.
        * unroll.c (iteration_info): Extend the biv initial value for the giv.
        (find_splittable_givs): Likewise.
        (final_giv_value): Likewise.

From-SVN: r36250