* replace part of the old implementation, test=develop

* restore concat op, test=develop

* update all ops implemention & delete GetDataTypeOfVar func, test=develop

* add more err msg, test=develop

* add more unittests, test=develop

fix ExecutionContext::HasInput and ExecutionContext::HasOutput depend on the scope structure, test=develop (#20721)

* add support to gcc8, add docker env test=develop

Add IndicateVarDataType interface to block tensor is not initialized problem in OP GetExceptedKernelType (#20044)

* add indicate_var_data_type inferface, test=develop

* add unittests & polish error message, test=develop

* remove needless include, test=develop

* extract public function & polish message, test=develop

* delete empty var check, test=develop

* change data_type to pointer parameter, test=develop

* polish details, test=develop

* add pybind interface to get all inplace ops, test=develop

* enhance OpTest to check whether the consistency of operator when using and not using inplace, test=develop

* handle corner cases in op_test, test=develop

* support outputs without tensor holder_, like XShape in reshape_op, test=develop

* fix bug, some op has GradOpMaker, but actually no grad_op in OpInfoMap, test=develop

* use reshape_grad instead of reshape in FlattenGradOp, test=develop

* fix error debug dims info for variables like XShape, test=develop

* change computational order in sum_op to relieve computation difference using inplace, test=develop

* add inplace_atol to check group_norm, and skip inplace_grad for mkldnn, test=develop

* follow sneaxiy's comments, test=develop

* remove unused DefaultGradOpDescMaker in mkldnn op, test=develop

* Add call stack info during runtime and compile time
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* Rename operator_call_stack
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* Add unit test
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* follow comment
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* not use transferscope cache in cpu case

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* adjust variable name and add comments

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* use correct format for class member in operator.h

* use correct format for class member in operator.cc

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Async exe support communicator

* add cache_update_mutex_ for operator 

This reverts commit aca60e9a.

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* fix comments of 16410, test=develop

* modify inplace_op_inference_test according to pass interface change, test=develop

* fix cdn issue, test=develop

* fix memory optimize bugs, test=develop

* fix memory optimize bugs, test=develop

* remove add/sub_2 op, test=develop

* disable memory_optimize by default, test=develop

* disable inplace activation in python, test=develop

* fix unittests, test=develop

* fix unittests, test=develop

* bug-fix, test=develop

fix ctest eager deletion disable bug
test=develop

refine gc code
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