* mem opt

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* refine code  test=develop

* refine code  test=develop

* refine code  test=develop

* refine code  test=develop

* refine with cub test=develop

* fix mkldnn test && remove comments && test=develop

* polish code && test=develop

* add only_forward test && test=develop

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* fix mac cmake version 3.13 test=develop

* fix again test=develop

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* refactor tree2col operator with new memory mechanism test=develop

* test=develop

* test=develop

* Modified API according to panyx0718 test=develop

* fix API change according to heavengate test=develop

* Modify API comment test=develop

* Revert the modification of while_op in #14764.
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* Remove the dependency of GRPC_DEPS.
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* Simplify the compare op for CPU.

* Use asynchronous tensor copy in reshape_op's kernel.

* Optimize while_op for test, avoiding creating variables every time.
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* Enable the cache of kernel type and kernel function.
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* Enable profiling with gperftools.

* Remove flags for testing, and fix the linking error.
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* Delete the codes of ChooseKernel.
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* Fix bug when preparing ExecutorPrepareContext for while_op.

* Fix missing depending on grpc libraries.

* Remove the redundant print.
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* Follow comments.

* Remove the codes related to prepare the ExecutorPrepareContext for while_op.
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This reverts commit 358e657f.

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This reverts commit 064512aa.

* remove workspace_handle in conv2d_cudnn
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* remove workspace_handle
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* fix bug
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* make test_conv2d_op SERIAL
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* save memory in conv_cudnn
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* enhance thread safety
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* enhance temporary allocator
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* Add excess fraction
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* follow comments
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* fix bug and code refine
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* fix memory size check
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* rename reuse_tmp_allocation_excess_fraction
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* Enable basic MKL-DNN INT8 Conv OP
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* Modify test case
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* Clean unittest code
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* Fix test
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* Modify test
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* Enable MKL-DNN INT8 Conv with Relu Fusion OP
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* Enable INT8 Conv with residual fusion OP
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* Modify code.
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* Modify basic INT8 Conv
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* Modify Conv.
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* fix style
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* Fix style
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* Fix test
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* Modify code.
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* Fix test
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* clip softmax for fp16

* updates

* fuse xent support fp16 test=develop

* wip

* wip

* add simple row reduce

* wip fp16 accurate softmax

* add accurate softmax kernel for fp16 test=develop

* update test=develop

* fix cpu build test=develop

* update api.spec test=develop

* follow comments test=develop

* fix build test=develop

* fix trt build test=develop

* fix inference build test=develop

* fix merge test=develop

* update test=develop

* try fix build test=develop

* fix build test=develop

* rename real_exp test=develop

* fortest

* remove hacky kernels test=develop

* clean up test=develop

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