* add double grad implementation for dygraph, test=develop

* polish code, add uts, test=develop

* fix place bug, test=develop

* polish codes, add more uts for coverages, test=develop

* add no_grad_set, test=develop

* add star gan ut, test=develop

* follow comments, test=develop

* refine grad maker, test=develop

* refactor tracer stage 1, test=develop

* merge develop to solve conflict third times, test=develop

* update layers, test=develop

* fix input numpy, test=develop

* fix bugs, test=develop

* follow commments, test=develop

* update getitem, test=develop

* dygraph_grad_maker supports varbase without grad_var, test=develop

* fix compile, test=develop

* fix test_tracer, test=develop

* follow comments, test=develop

* add overrider for virtual function; test=develop

* fix layer.h OutputName bug; test=develop

* support SelectedRows in dygraph, test=develop

* fix bug of _grad_ivar interface, test=develop

* add optest for support seletedrows, test=develop

* fix bug for gradient_accumulator in GPU mode, test=develop

* fix error when Selectedrows addto LodTensor in sorted_gradient mdoe in dygraph, test=develop

* refine and simplify gradient accumulator code, test=develop

* add optest, test=develop

* add optest and simplify code, test=develop

* fix bug for test_imperative_selected_rows, test=develop

* add optest for Coverage, test=develop

* fix gradient interface and simplify code, test=develop

* update api for gradient, test=develop

* fix ShareDim's bug in DygraphExecutionContext class, test=develop

* add optest, test=develop

* add_dygraph_execution_context

* add dygraph infershape context and execution context; test=develop

* fix imperative bug; test=develop

* remove inputs outputs interface from execution context,
because it have same function with inputNames;
test=develop

* remove tracer_test ctest; test=develop

* fix split op bug; test=develop

* fix unitests bug; test=develop

* fix distribute test bug; test=develop

* fix ngraph compile bug; test=develop

* fix grad maker bug; test=develop

* fix load op bugs; test=develop

* fix operator.cc construct bug; test=develop

* remove useless name find in operator; test=develop

* add tracer_test; test=develop

* fix concat, split bug; test=develop

* remove tracer_test unitest; test=develop

* fix attribute check bug; test=develop

* add test code to fix converage; test=develop

* remove useless code, change check backward input in engin; test=develop

* unlock var type infer shape;test=develop

* add ShareAllLoD api; test=develop

* add dygraph infershape context unitest; test=develop

* remove increase and decrease lod in dygraph; test=develop

* addd override; test=develop

* fix increase descrease lod; test=develop

* fix paddle_enforce; test=develop

* disable lod op dygraph check; test=develop

* fix paddle enforce error; test=develop

* add comment for op_registry and OperatorBase; test=develop

* optimize the comment of op_registry; test=develop

* fix format of comment; test=develop

* fix format of comment; test=develop

* optimize the format of comment; test=develop

* optimize the format of the comment; test=develop

* optimize comment of op_registry; test=develop

* open dygraph op test, test=develop

* modify to_variable, test=develop

* modify input and output for dygraph, test=develop

* modify input and output for dygraph(fix bug), test=develop

* fix input processing of dygraph op test, test=develop

* fix bug, test=develop

* fix op test, test=develop

* fix forward bug for dygraph, test=develop

* fix mkldnn op test for forward, test=develop

* update nn.py for dygraph, test=develop

* fix crop_tensor_op, test=develop

* fix elementwise_mul_op, test=develop

* fix fill_op, test=develop

* fix some mkldnn op, test=develop

* open backward op test for dygraph, test=develop

* delete log, test=develop

* close backward op test for dygraph, test=develop

* fix bug for edit_distance_op and test_lstm_cudnn_op, test=develop

* fix optest backward bug for dygraph, test=develop

* fix optest backward bug for dygraph, test=develop

* close backward op test for dygraph, test=develop

* close backward op test for dygraph, test=develop

* open dygraph op test, test=develop

* fix op test for dygraph, fix GradOpDescMaker, test=develop

* fix bug for linear_chain_crf_op.h, test=develop

* remove log, test=develop

* remove log, test=develop

* remove log for op_test.py, test=develop

* remove log for op_test.py, test=develop

* fix bug for var_conv_2d_op, change PADDLE_ENFORCE, test=develop

* fix PADDLE_ENFORCE_EQ for hierarchical_sigmoid_op.cc, test=develop

* fix bug for test_increment_ngraph_op.py, test=develop

* fix lod for op test in dygraph, test=develop

* refactor op_test.py to reduce redundant code, test=develop

* fix lod optest, modify InputVar/OutputVar to HasInput/HasOutput, test=develop

* remove debug log, test=develop

* remove redundant code in base.py, test=develop

* fix some error in optest, test=develop

* fix ClearNoNeedBufferInputs function's bug for LoDTensor, test=develop

* refactor op_test.py, test=develop

* remove redundant writing, test=develop

* fix error(get tensor of the grad variable), test=develop

* fix test_concat_mkldnn test_conv2d_mkldnn, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix some redundant code, test=develop

* reslove conflict and rewrite paddle error message, test=develop

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* optimize grad maker; test=develop

* optimize grad maker

* test

* grad make optim; test=develop

* fix unittest bugs; test=develop

* add dygraph grad op maker and split_op

* grad op maker refactor; test=develop

* add dygraph grad maker; test=develop

* fix op deformable_conv_v1_op bug; test=develop

* fix deformable_conv prroi pool bugs;

* fix new op grad op maker bug; test=develop

* fix split by ref bug; test=develop

* fix dygraph auto prune bug; test=develop

* fix test_trace bug; test=develop

* fix fused emb seq pool bug; test=develop

* remove useless code in op_desc file; test=develop

* remove useless code, StrVarBaseNode; test=develop

* fix review issues; test=develop

* fix rank_loss grad maker; test=develop

* remove flag in VarBase; test=develop

* fix distributed_notify_op compile bug ; test=develop

* fix reshape op double grad; test=develop

* fix expand as op; test=develop

* add impertive type_defs.h for demo_train; test=develop

* fix inference lib cmake; test=develop

* fix inference lib; test=develop

* fix infernce_lib; test=develop

* fix inference cmake; test=develop

* fix inference lib; test=develop

* fix inference lib; test=develop

* remove condition dygraph grad maker, modify local name; test=develop

* fix split grad maker bug; test=develop

* fix pyramid_op bug; test=develop

* change travis time out limit; test=develop

* restore travis; test=develop

* change timeout limit; test=develop

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* test=develop, refoctor name to make it easier to understand

* test=develop, refoctor name to make it easier to understand

* test=develop, fix multi-gpu failed problem , add Tracer tests, change PADDLEENFORCE to PADDLEENFORCE_EQ

* test=develop, fix ut failed on parallel se-resnext

* test=develop, change one more PADDLE_ENFORCE

* support auto prune in dygraph mode

* test=develop, support auto prune

* test=develop, merge develop conflict

* test=develop, fix test_layer and test_tracer ut

* test=develop, fix bug which may cause stop_gradient disabled with a list of backward inputs

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* test=develop, refoctor name to make it easier to understand

* test=develop, refoctor name to make it easier to understand

* test=develop, fix multi-gpu failed problem , add Tracer tests, change PADDLEENFORCE to PADDLEENFORCE_EQ

* test=develop, fix ut failed on parallel se-resnext

* test=develop, change one more PADDLE_ENFORCE

* fix dygraph mem leak, test=develop

* polish msg, test=develop

* for debug

* test=develop, memory optimize for dygraph using shared_ptr

* test=develop, fix travis ci showed error

* test=develop, fix bug for recurrent usage of varbase

* test=develop, init varbase when it need to be Add

* test=develop, fix problem of recurrent gradient

* test=develop, add gradient test for recurrent varbase usage

* for debug

* test=develop, memory optimize for dygraph using shared_ptr

* test=develop, fix travis ci showed error

* test=develop, fix bug for recurrent usage of varbase

* test=develop, init varbase when it need to be Add

* add var grad hook test=develop

* test=develop, add gradient sort backward strategy

* test=develop, fix test by add FLAGS_cudnn_deterministic on new tests

* test=develop, fix memory leak in dygraph mode

* test=develop, fix memory leak in dygraph mode

* test=develop, polish code

* test=develop, polish code

* test=develop, polish code

* test=develop, add gradient sort backward strategy

* test=develop, fix test by add FLAGS_cudnn_deterministic on new tests

implement dygraph.parallel.DataParallel to hook reduce op.

test=develop

test=develop

test=develop

test=develop

test=develop

* Remove Desc in Forward Pass

* Refactor VarBase

* Add dbg info

* Only check type in imperative mode

* Polish code and support optimizer

test=develop

* Fix stop gradient problem in PyLayer

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop