* Refine the InferShape of ReadFrom and WriteTo op, and add comment to explain why not call ShareLoD for runtime.
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* Add comment for ReorderLoDTensorByRank op.

* Add comment for lod_tensor_to_tensor_array op to explain why only call DecreaseLoDLevel for compile time.
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* ShrinkRNNMemory op should call ShareLoD for compile time.
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* Add the implementation of IncreaseLoDLevel and add the compile-time check of lod_level in InferShape of sequence_pool.
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* Refine the unittest of DynamicRNN.
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* Change PADDLE_ENFORCE to PADDLE_ENFORCE_NE.
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* replace part of the old implementation, test=develop

* restore concat op, test=develop

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

* Set lod level of sequence_unpad's output to 1 in compile time

* add lod check for sequence op, test=develop

* delete unnecessary check in expend op, test=develop

* Removing last dims constraints of seq_pad and seq_unpad test=develop

* fix test_layer api code test=develop

* fix sequence_pad_op.cc conflict test=develop

* remove test_analyzer_mm_dnn test=develop

* fix vectorize bug test=develop

* fix vectorize<int> test=develop

* support 2-level lod of input in sequence_pool test=develop

* fix lod level bug in .cu test=develop

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* add topk_avg_pooling

* refine api doc and modify api.spec test=develop

* Add the check of lod in sequence_softmax kernel.
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* Refine the comments.
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* 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;
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* 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

* Use TensorCopySync for sequence_unpad op

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* Fix the tensor memory alloc bug

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Fix bug in sequence_unpad op, when allocate the output memory do not match actual memory, check memory failed. Fix this bug by allocating the output memeory in correct code position.

* Enable seq_pool op to accept len 0 input

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* Update sequence_pool's api

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* Add more unittest cases for seq_pool op

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* Remove legacy comments

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* Don't use template in op maker

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* Optimize the computing kernel of sequence_reverse operator.

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* Clean code

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* Fix for cpplint syntax checking.

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* Fix the compile warning issue.

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* Support seq len equal to 0 in sequence ops

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* Add more test cases

* Fix some comments

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* Fix py3 error

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* fix overflow by int32 mul test=develop

* fix reference nullptr

* fix codestyle test=develop

* modify to point in ContextProjectFunctor test=develop

* modify to point in ContextProjectFunctor test=develop

* modify . to -> test=develop

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Optimize the CUDA implementation of sequence_expand op by reduce the times of copying lod data from CPU to GPU. (#15493)

* Optimize the CUDA implementation of sequence_expand op by reduce the times of copying lod data from CPU to GPU.
test=develop

* Refine the op benchmark to support setting lod in config.
test=develop

* fix warnings

test=develop

* fix enforce test

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* Add check of input in sequence_expand op.
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* Correct the unittest of sequence_expand op.
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* code style fix, test=develop

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The macro should be defined by compiler rather than by source.

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