Issue
when try vta on fpga board, would see a Infinite recursive
device_api.ext_dev issue that cause stack overflow and vta
failed.

Analysis:
device_api.ext_dev function in rpc_server.py is use to load
vta library, once vta library get load, device_api.ext_dev would
get replaced with vta function by vta library, vta device_api.cc
did such work, but because a logic issue in VTA.cmake, the said file
not get compiled, then vta would keep failing on rpc_server.py.

Solution:
fix the logic issue in VTA.cmake.

Issue:
RewriteForceSerial is a debug function to force instructions
to be serialize instead of parrallel running, by doing so we
can isolate some parallel problem or do performance compare
between parallel and serialize. But this function have some
problem, once get enabled by set debug flag, vta would stuck
when running on pynq board.

Analysis:
once enable RewriteForceSerial, the dependency logic is different
with default one, but we still use same logic to generate FINISH
and other logic, this would cause dead lock.

Solution:
give a different dependency settings when enable RewriteForceSerial.

* [Relay] Conv2d grad

* Fix test

* Fix first order gradient

* Not assuming HOME in tvm/download.py

* Trigger notification

* [TensorFlow] Fix limitation that depth_mult can only be 1 for DepthwiseConv2dNative

* Improve code readability

* [AutoTVM] Fix database APIs

* Refactor the byte conversion

* [Relay][Keras] Dot

* fix reshape

* fix comments

* fix inconsistent python/cpp APIs for if_then_else

* fix error message

* fix power consistency

* fix

* fix bug

* add test

* initial virtual memory;

* initial integration;

* include the header file in cmake;

* implement allocation with virtual to logical address mapping;

* virtual memory for tsim_driver;

* implement the missing memory release function;

* readability improvement;

* readability improvement;

* address review comments;

* improved robustness in virtual memory allocation;

* remove VTA_TSIM_USE_VIRTUAL_MEMORY macro and use virtual memory for tsim by default;

* link tvm against vta library;

* merge with master

* build virtual memory system without linking tvm against vta;

* minor change;

* reuse VTA_PAGE_BYTES;

* using DRAM class from sim_driver as VirtualMemoryManager;

* satisfy linter;

* add comments in code;

* undo changes to Makefile

* undo changes to Makefile

* retrigger ci;

* retrigger ci;

* directly call into VirtualMemoryManager::Global()

Fixed repo change for llvm-9 to resolve missing dependency issue when building images with llvm enabled (#3826)

transform.h:118:3: warning: 'const' type qualifier on return type has no
effect
attrs.h:68:3: note: expanded from macro 'TVM_DECLARE_ATTRS'
node.h:244:3: note: expanded from macro 'TVM_DECLARE_NODE_TYPE_INFO'

transform.h:95:3: warning: extra ';' after member function definition
attrs.h:68:62: note: expanded from macro 'TVM_DECLARE_ATTRS'

* Add one-hot to Relay

* topi implementation

* Working

* add topi test

* Add TF test

* Fix check

* fix linting issues

* fix documentation

* Fix documentation

* Add support for on_value, off_value, axis, dtype

* Add full support for axis

* Fix compute and update test_forward

* Move on_value and off_value to inputs

* Add topi test

* Update tests

* Update docs

* Fix style

* re-enable tests

* Add one_hot to mxnet converter

* Support cblas library in dense

* start to add support for generic batch_matmul compute

* Add x86 override for batch_matmul

* Fix linting

* reset file

* Fix typos

* dummy change to re-trigger CI

* [Relay][VM]VM debugger

* Report mean/min/max for op duration

* Typos

* Lint

* Lint

* Lint

* Support build debug VM in CMake

* Lint

* Enable VM debug in unit test

* Disable debug vm test until new docker image is built

* Add device sync code

* Fix qnn unit test

* Disable vm debug by default

* Rename files

* Rename classes

* Fix comment

* Fix comment

* transpose implementation for tflite.py

* add TRANSPOSE to convert_map

* Fix Unexpected keyword argument 'axis' in function call

* add test for transpose oprator

* Add the parameter 'axes' handling

* add test for transpose oprator

* solve conflict within CONTRIBUTORS.md

* Improve the if condition for empty tuple

* Add one unit test to cover empty tuple

* solve conflict within CONTRIBUTORS.md

* Fixed onnx test failures when run on a cpu backend

* Updated check_torch_conversion function to include output comparison

[CoreML] Solve CoreML frontend issue of image scaler and padding so that Mobilenet mlmodel can work correctly. (#3800)