add best practices for win

Best-Practices-to-Edit-and-Compile-Pytorch-Source-Code-On-Windows.md

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+[[Page Maintainers | Best Practices to Edit and Compile Pytorch Source Code On Windows]]:: @mszhanyi
+
+## Goals
+In this wiki, I'll introduce best practices to work with PyTorch C++ Source code on Windows. To some extent, developers could get the better experience with Visual Studio than on Linux.
+
+## Prerequisites:
+At first, We need to build the debug version libtorch On Windows. You can refer [building libtorch](https://github.com/pytorch/pytorch/blob/master/docs/libtorch.rst) to build it. 
+
+## Start Visual Studio correctly
+Once the libtorch built, please copy the directory of the libiomp5md.dll and add it to the PATH.
+![where libiomp5md.dll](image/libiomp5.png)<br>
+For me, I use a bat to start Visual Studio
+```
+set PATH=D:\programs\envs\nightly\Library\bin\;%PATH%
+"D:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Common7\IDE\devenv.exe"
+```
+
+Another way is to start Visual Studio in the Conda Windows where libtorch is built
+
+## Use VsChromium
+As we know, for performance, PyTorch only officially support Ninja as the CMake generator. As the result, we could not manage and navigate Pytorch Source Code via Visual Studio Solutions/Projects. Luckily, there's a better option. 
+
+[VsChromium](https://chromium.github.io/vs-chromium/) has been become a more general purpose extension that can be userful for any project. Its full text search engine is much more faster that search/replace in visual studio. 
+For more details, please read through https://chromium.github.io/vs-chromium/.
+
+Don't forget to add vs-chromium-project.txt into your PyTorch root directory.
+For conveniently, you could copy mine directly.
+```
+[SourceExplorer.ignore]
+.git/
+third_party/
+*.suo
+*.csproj
+*.vcxproj
+[SearchableFiles.ignore]
+build_libtorch/
+*.pdb
+*.exe
+*.dll
+[SearchableFiles.include]
+*
+```
+
+## Example
+In this section, I'll demo how to add one printf in test/cpp/api/nn_utils.cpp,  compile  and debug it.
+1. Start Visual Studio Correctly
+2. Open Project/Solution, select test_api.exe.
+   ![open test_api.exe as solution](images/bestpractices_win/testapi.png)
+3. Open Setup.py or any other source file, then it starts loading all source files right away. The Visul Studio should look like the below snapshot.
+   ![load source code](images/bestpractices_win/vschromium.png)
+4. Add one printf in test/cpp/api/nn_utils.cpp as below, and `run python ../tools/build_libtorch.py` to recompile.<br>
+   Since increment build with Ninja for Pytorch has been supported on Windows.
+   For such small change, It only takes about one minute to compile.<br>
+   ![Printf](images/bestpractices_win/printf.png) 
+5. Then, we could add a breakpoint and click *Start* to debug it.
+   To save time, we could add a gtest_filter.
+   ![gtest_filter](images/bestpractices_win/gtestfilter.png)
+
+## One Reminder
+You might find some changes you made doesn't work and after recompiling, the changes dismissed. That is because some PyTorch C++ code is generated in compile.