rs6000.c (rs6000_pre_atomic_barrier): Remove SYNC variants cases from switch.

rs6000.c (rs6000_pre_atomic_barrier): Remove SYNC variants cases from switch.

       * config/rs6000/rs6000.c (rs6000_pre_atomic_barrier): Remove SYNC
        variants cases from switch.
        (rs6000_post_atomic_barrier): Same.
        (rs6000_expand_atomic_compare_and_swap): Use memmodel_base.
        (rs6000_expand_atomic_exchange): Same.
        (rs6000_expand_atomic_op): Same.
        * config/rs6000/sync.md (mem_thread_fence): Use memodel_base. Remove
        SYNC variants cases from switch.
        (atomic_load): Same.
        (atomic_store): Same.

From-SVN: r224401