From: @zhaosida_hw
Reviewed-by: @zhoufeng54,@jjfeing
Signed-off-by: @jjfeing

From: @lianliguang
Reviewed-by: @kisnwang,@zhoufeng54
Signed-off-by: @zhoufeng54

From: @nicholas_yhr
Reviewed-by: @kisnwang,@zhoufeng54
Signed-off-by: @zhoufeng54

From: @lianliguang
Reviewed-by: @zhoufeng54,@chujinjin
Signed-off-by: @chujinjin

From: @wenfangpei
Reviewed-by: @gaoxiong1,@anyrenwei
Signed-off-by: @anyrenwei

From: @tronzhang
Reviewed-by: @gaoxiong1,@anyrenwei
Signed-off-by: @anyrenwei

From: @yuchaojie
Reviewed-by: @zhoufeng54,@jjfeing
Signed-off-by: @jjfeing

From: @looop5
Reviewed-by: @gaoxiong1,@gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @chenlei_autodiff
Reviewed-by: 
Signed-off-by:

From: @dayschan
Reviewed-by: @gaoxiong1,@gaoxiong1,@anyrenwei
Signed-off-by: @anyrenwei

refactor CanActivateAtomicAdd

use smart pointer

From: @ding_fei_fei
Reviewed-by: @kingxian,@zhunaipan
Signed-off-by: @kingxian

From: @zengzitao
Reviewed-by: @gaoxiong1
Signed-off-by:

From: @lingyunli63
Reviewed-by: @gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @looop5
Reviewed-by: @gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @liangzelang
Reviewed-by: @kisnwang,@jjfeing
Signed-off-by: @jjfeing

From: @tronzhang
Reviewed-by: @gaoxiong1,@gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @dayschan
Reviewed-by: @gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @linqingke
Reviewed-by: @guoqi1024,@xu-yfei
Signed-off-by: @guoqi1024

Decoupled the process of expanding node from GraphKernelExpander pass,
so that it can be rolled back when error occurs.

By the way, supported controlling cluster ops by flags.

From: @lingyunli63
Reviewed-by: 
Signed-off-by:

From: @lingyunli63
Reviewed-by: @gaoxiong1,@dylangeng
Signed-off-by: @dylangeng

From: @zyli2020
Reviewed-by: @cristoval,@limingqi107
Signed-off-by: @limingqi107

From: @limingqi107
Reviewed-by: @cristoval,@kisnwang
Signed-off-by: @kisnwang

From: @dayschan
Reviewed-by: @gaoxiong1
Signed-off-by:

used the flag "opt_level" to control GraphKernel,
0 means disabled while non-zero value means enabled.
the default value is controlled by context "enable_graph_kernel",
but if it's also set in "graph_kernel_flags", then the flag will prevail.

supported the whitelist and blacklist operators for GraphKernelExpander.
"enable_expand_ops", "enable_expand_ops_only", "disable_expand_ops".