toplev.c (flag_rerun_loop_opt): New variable.

toplev.c (flag_rerun_loop_opt): New variable.

        * toplev.c (flag_rerun_loop_opt): New variable.
        (f_options): Handle -frerun-loop-opt.
        (rest_of_compilation): If -frerun-loop-opt, then run the loop
        optimizer twice.
        (main): Enable -frerun-loop-opt by default for -O2 or greater.

From-SVN: r16180