Signed-off-by: zhoufeng <zhoufeng54@huawei.com>

Merge pull request !2771 from LiHongzhang/improve_docs

Merge pull request !2638 from jiangjinsheng/vm_mod

Merge pull request !2767 from wangqiuliang/fix-hook-operator-compare-issue

Merge pull request !2722 from Kang/optimization

Merge pull request !2747 from zhangbuxue/refactor_the_StridedSlice_op

Merge pull request !2514 from yoonlee666/gelu2

Merge pull request !2769 from ougongchang/fix_nonetype

Merge pull request !253 from wuxuejian/grad_embeddinglookup

Merge pull request !2720 from xychow/fix-assign-in-while

Merge pull request !2775 from ZiruiWu/better_get_dataset_size_in_generator

Merge pull request !2772 from Jamie/removalpass

cpplint

Merge pull request !2602 from JesseKLee/cache_op_stage2

Merge pull request !2766 from yanghaitao/yht_serialize_num_parallel_worker

fix get loss error when it not a scalar and fix process specified data
failed when the action is False, and collect_specified_data parameter is
not None

Merge pull request !254 from xutianchun/fix_mirror_pad_grad

Merge pull request !2760 from JesseKLee/gcc9

Merge pull request !2762 from YuJianfeng/master

Merge pull request !2746 from lichen/remove_32byte_limit_for_cpu_gatherv2

Merge pull request !2699 from zhaozhenlong/op/scatter-max-vm

add copyright

Merge pull request !2756 from wenchunjiang/fix_control_sink_bug

Merge pull request !1904 from riemann_penn/add_indexed_slices

Merge pull request !2753 from xiefangqi/xfq_fix_docstring

Merge pull request !2743 from ougongchang/summary_collector_ut

Merge pull request !2741 from jiangjinsheng/issue_fix4