* flow.c (make_edge): Early out, if no flags to set.
        (calculate_global_regs_live): Clear out garbage only when necessary.

        * simplify-rtx.c (varray_type used_regs): New.
        (clear_table): Use it to only clear necessary items.
        (cselib_lookup, cselib_record_set): Remember newly set items.
        (cselib_update_varray_sizes, cselib_init): Initialize and grow
        used_regs.

        * local-alloc.c (update_equiv_regs): New local `cleared_regs'.
        Move clearing of dead regs out of insn-loop.

From-SVN: r37899