* rewrite the conv_op using cudnn_conv_helper

* add workspace limit for v7 test=develop

* fix test=develop

* add half float test=develop

* fix test=develop

* fix test=develop

* revise code style test=develop

* fix test=develop

fix mask rcnn
add interface for setting optim_cache_dir(eg: when in trt int8 mode, and load model from memory, there should be a interface for setting the trt calibration table data dir)

test=release/1.5

Add path to handle 1D vector

test=release/1.5

test=release/1.5

* test=develop

* test=develop

* fix mac build error

* test=develop

* fix

* add pm approval api.spec

* fix mac ci random fail
* use platform instead

test=release/1.5

* fix py-cpuinfo mac random fail
* differentiate version on windows

test=release/1.5

test=release/1.5

* fix mac build error

* test=develop

* fix

* change nproc 8

* test=release/1.5

* fix mac build error

* test=develop

* fix

* Update lamb optimizer (#18333)

* Update lamb optimizer

* Regenerate api spec

test=release/1.5

* Give an experimental warning

test=release/1.5

* Simplify multi_box_head API in detection.py and remove assign op.

BackwardStrategy
dygraph.nn
dygraph.checkpoint

*  add cuda_is_available
test=release/1.5

* Update the Anakin interfaces for content-dnn and MLU (#17890)

* update anakin-engine interfaces for content-dnn

test=develop

* support only-gpu mode of Anakin

modify eltwise parse

test=develop

* modification for thread-safe

test=develop

* Integrated template instance

test=develop

* increase template parameters

test=develop

* support MLU predictor

test=develop

* update anakin cmake files

test=develop

* update TargetWrapper::set_device

* update the initialization of anakin subgraph

test=develop

* use the default constructor of base class

test=develop

* modify the access level of anakin engine (#18015)

test=develop

* fix ci test cmake test=develop

* update pe reduce config
test=release/1.5

*  drop the local_exe_scopes of the previous parallel_executor
test=release/1.5

test=release/1.5

* fix softrelu doc
* update API doc

test=release/1.5

* sequnce mask support max length tensor input; test=develop

* add rnn_impl.py; test=develop

* add basic gru lstm unittest; test=develop

* fix api spec; test=develop

* fix sequence_mask op bug;
test=develop
test=document_preview

* change +-*x to elmentwise_op; test=develop

* add mkl flag; test=develop

* fix rnn impl bug; test=develop

* update api spec; test=develop

* fix doc bug; test=develop

* fix lstm bugs; test=develop

test=release/1.5

* Fix the GetExpectedKernelType of add_position_encoding_op.

* Fix the doc of lstm_unit outputs in nn.py.

test=release/1.5

* fix default value of fluid.memory_optimize
test=release/1.5

* Use TensorCopySync for sequence_unpad op

* Fix the tensor memory alloc bug

test=release/1.5

add dygraph api doc for fluidDoc and api spec

* fix slice op bug; test=develop

* fix variabel test bug; test=develop

* remove slice while true; test=develop

test=release/1.5

Repair error prompt: Users are prompted to check whether the model or parameter files are damaged when loading parameters are wrong.

* cherry pick 18000, test=release/1.5

* cherry-pick the inference update for win test=develop

* test=develop

* update some op doc, test=release/1.5

* Update backward appending stragety to support double backward and fix some bug. (#18104)

* Update backward.py:
     - If there is no input grad var in all outputs of previous ops, do not append this op into graph.
     - Only apply this stragety when double backward.
* Update some double backward op.
* Update sum_op to judge whether a tensor is empty by numel or IsInitialized().