Optimize cpp reader

* fix mistakes in merge_ids, test=develop

Add check: conv_fusion op runs with cudnn version > 7100 .

* enable ngraph_engine_op
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* merge develop test=develop

* avoid const_cast test=develop

* rm ngraph_operator test=develop

* Added TODO to move EnableNgraph test=develop

* Add TODO to remove const_cast test=develop

test=develop

* Revert "set constant for loss"

This reverts commit 167933f678ccbb3563e949710279efe004a27731.

* Revert "remove workspace_handle"
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This reverts commit b4aca8ede9e685bce1dfb1c59e63919f33432572.

* Refine the beam_search op and test.

* A basic CUDA implementation of beam_search for small batch_size.

* Implement CUDA kernel for beam_search_op.

* Use multiple CUDA threads in the same block to select the top beam.

* Update the python api of beam_search op.

* Enable extend function in CPU kernel of beam_search op.

* Unify the CUDA codes.
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* Unify the CPU kernel of beam_search op.

* Ensure the seletced items of beam_search_op's CPU kernel sorted by scores.

* Update the description of beam_search in API.spec.

* Enable the use of CUDA kernel in beam_search op.

* Exclude the beam_search's CUDA unittest when there is no CUDA gpu, and delete some debuging statements.
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* Follow comments.
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* Call the CPU kernel for beam_search op when batch_size > 4.
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* Remove the except of is_empty op in PrepareData.
test=develop

Disable eager deletion unittest temporarily since random failure.

Fix bug when user set CUDA_VISIBLE_DEVICES be empty and run CPU-only models

Turn on remove_unnecessary_lock by default

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* nce add check sample lables, test=develop

test=develop

Add check for it.
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fix debug compile issue of analysis pass

* fix github issue 15267 test=develop

* fix github issue 15267 test=develop

* monitor the GPU usage during runtime

* revert allocator_facade.cc change

* comments update test=develop

Imperative Resnet

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Optimize assign

* Add the calibration tool code for int8 inference and focus test.

* Fix the calibration tool per the review comments.

test=develop

* Update the calibrator doc and remove extra line.

* Fix the invalid is_negative_input attr set on Mobilenet.

* Add the comments and fix the format issue.

test=develop

* Update the CMakelist.txt for Calibration PR.Disable the Calibration UT if not enable MKLDNN.

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* Update the CMakeList.txt.

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* Disable the test_calibration case on WIN and MAC.

test=develop

* Add the missing brackets.

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* Remove the outdated map operator which not supported on Python3.

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* Fix the style issue.

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* 1.Update the CMakeList.txt to disable calibration tool ut when the WITH_MKL is not set;
2.Add the workaround to enable the FLAGS_use_mkldnn for PR_CI(PADDLE).

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* Fix the typo and format the License header.

test=develop

* 1.Add and Update TODOs per review comments.
2.Code clean.

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fix trt stream bug.

checkpoint for distributed training.

test=develop

* Add generate_mask_labels_op to support Mask-RCNN.
* Refine sigmoid_cross_entropy to support nomalize mode.
* Fix generator_proposals_label.
* Use DeviceTemporaryAllocator in roi_pool and roi_algin.
* Remove shape check in data_feeder.

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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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Graph quantization pass. TODO(Add public API comments.)