* loop.c (loop_giv_reduce_benefit): Break out from strength_reduce.
	(loop_givs_dead_check, loop_givs_reduce, loop_givs_rescan): Likewise.
	(prescan_loop): Set pre_header_has_call in loop_info.
	* loop.h (struct_iv_class): Add `final_value' and `all_reduced'.
	(struct loop_info): Add `pre_header_has_call'.

From-SVN: r38578