* expmed.c (const_mult_add_overflow_p): New.
        * expr.h: Declare it.
        * loop.c (maybe_eliminate_biv_1) [COMPARE]: Use it.
        Don't eliminate the biv if the giv has a constant multiplier and
        the rhs argument of the comparison does satisfy the predicate.
        Use expand_mult_add to compute the replacement constant.

From-SVN: r54075