Accelerate SelectedRows Functors:

* add strategy doc
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* fix doc
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* add ParallelExecutor arg doc
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Add trt pad op converter

Revert "Make variable::GetMutable robust"

Make variable::GetMutable robust

Explain LoD and a few other concepts

fix demo_ci bug in vis_demo.cc

* fix layers.uniform_random

* fix uniform_random
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* remove var type set
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* fix similar error
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This can cause a lot of problem:
1. Wrong operator implementation, Op can get a wrong type without failure.
2. Anytype can be Get without defined in VarType.

Also fix wrong STEP_SCOPE usage.

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* optimize depthwise conv by register memory
* test=develop

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* profiler infor merge thread statistic information

* update profiler

* fix bug

* add merge thread msg to report

* optimize report

* statistic the time of ops in each thread but not all

* optimize report format

* optimize profile report

* optimize profile report
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Merge selected_rows for clip_by_norm op

  1. Accelerate SelectedRows MergeAdd functor

  2. Add SelectedRowsSumTo functor to support MergeAdd multiple SelectedRows into one

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Revert "[MKLDNN] Pass: Fuse Conv + Bias"

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[MKLDNN] Pass: Fuse Conv + Bias

* Fix truncated normal.

* test=develop

Sfraczek/conv bn fuse pass

add trt api lib to paddle_fluid lib

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Unit test to Fused_embedding_fc_lstm op

Fix flowers data read in python3

Make cmake support compile in MacOSX 10.14

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Revert "optimize pyreader"

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* set the right shape of selected_rows
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* enhance check

* fix activation_op

* remove cast

* use ShareDimInfo replace SetDim and ShareLod

* use ShareDimAndLod
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* follow comment

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* check whether the input has lod
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* Split ShareDimAndLod

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* checkout clip.py
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fix lod tensor