Revert "cache runtime_context"

* Make step_input support custom lod level.
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* Fix API.spec
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* Fix API.spec.
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* Fix API.spec
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* Add default value in document of step_input.
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* Fix document.
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* Fix API.spec
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Fix concat

refine sequence enumerate op

Implement imperative infer var type

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* - Fix to crash of Transformer when mkldnn is to be used

Desc: TensorCopy was not setting MKLDNN primitive descriptor when layout was to be kMKLDNN

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* - Enable transformer for mkl-dnn

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* - Compilation fix

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* - Removed manual selection of MKL-DNN ops to be used in Transformer test

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* Add cpu_quantize_placement_pass for C-API quantization

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* added a comment on required pass attributes

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cache runtime_context

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Remove const_cast in optimizers

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* Enable INT8 transpose kernel for MobileNet-SSD improvement.
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* Refine the license year.
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* Delete redundant code.
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* Add axis check.
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add more imperative layer tests.

refine fc_infershape

* update load persistables for increment, test=develop

* update load persistables for increment, test=develop

* update API Spec, test=develop

* update API Spec, test=develop

* add doc, test=develop

* add doc, test=develop

* Update lookup_table_utils.py

* Update API.spec

* Update lookup_table_utils.py

test=develop

* Update API.spec

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* fix api spec

* Update lookup_table_utils.py

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Improve imperative mode training speed

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* Add cpu_quantize_pass for C-API quantization

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* add cpu_quantize_pass test

* fix lint: add include memory unorderd_map and unordered_set

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* fuse_relu 1

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* tuned 2 without squash

* fixes

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* remove unused vars

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* refactored

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* fix lint c-style cast -> C++ style cast

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* remove QuantMax and c style casts

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* last usage of QuantMax removed

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* Fix Analysis Predictor UT

Check if memory_optimize_pass has already been added
to the analysis config before adding a new one, so
that it is not added multiple times.
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* change map to unordered_map

fix the forgotten part of cpu_quantize_pass_tester.cc

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* removed quantized attribute

* fixed cpu_quantize_pass_tester and op attr comments

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* removed redundant line

test=debug

* removed gmock

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* fix after merge

graph neural network for imperative mode

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improve layers.fc api doc

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add yolo_box for detection box calc in YOLOv3

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