docs/getting_started_on_windows.md - 3p/openxla/iree - Git at Google

 # Getting Started on Windows

 There are multiple ways to develop on Windows, and compared to other
 environments, batteries are often not included. This document outlines the setup
 that is known to work for the IREE developers. Other setups almost certainly
 work as well.

 ## Pre-requisites

 ### Enable Developer Mode

 We use symlinks in the build, and this requires developer mode to be enabled:

 *   Open Settings
 *   Search for "Developer Settings"
 *   Select the radio button "Developer mode" and accept all prompts

 ### Install Build Tools For Visual Studio

 At the time of writing, this can be found by going to
 [this page](https://visualstudio.microsoft.com/downloads/) and finding the
 Download link for "Build Tools for Visual Studio 2019".

 Minimally select to install "C++ Build Tools".

 ### Install the Scoop Package Manager

 The [Scoop page is here](https://scoop.sh/). Follow the instructions at the
 bottom.

 IMPORTANT: When launching PowerShell, make sure to not select any option that
 ends in "(x86)" as this will install the 32bit version, and all of the software
 that Scoop installs will be 32bit. While 32bit builds of the project may be
 possible, we only (presently) support 64bit. Also, not all packages are
 available in 32bit.

 ## Install Scoop Packages

 ### Home Directory

 Optional: Set the msys2 home directory to your Windows home directory. By
 default, the msys2 HOME will be nested inside the installation directory, which
 is managed by scoop and somewhat ephemeral.

 *   Open the Windows environment dialog (This PC -> Properties -> Advanced
     Settings -> Environment Variables...)
 *   Add a new User variable: `HOME` = `C:\Users\%USERNAME%` (replacing with the
     actual location of your Windows home directory).
 *   Ok out of all dialogs
 *   Restart PowerShell
 *   Verify that it took effect (`Get-ChildItem Env:HOME`)

 While here, also consider adding `GIT_SSH=C:/Users/%USERNAME%/scoop/shims/ssh`
 which will help git find the right SSH and keys (you probably want this as a
 global to Windows vs just in your shell, which is why it is recommended here).

 ### Scoop Package Setup

 In PowerShell, run the following:

 ```shell
 scoop install git nano vim
 scoop bucket add extras
 scoop bucket add versions
 scoop install msys2
 scoop install curl cmake openssh python36 llvm bazel
 # Optional
 scoop install vscode
 ```

 TODO: Upgrade to head python.

 Check the .bazelversion file for the version of Bazel you should install. You
 can also use [Bazelisk](https://github.com/bazelbuild/bazelisk) to manage Bazel
 versions.

 TODO: Specific steps to install a compatible version of Bazel directly

 ## Setup MSYS2

 Then run msys2 for the first time for subsequent setup by doing one of:

 *   Launch MSYS2 from the start menu
 *   From a regular PowerShell terminal (not ISE, which hangs), run `msys2`
 *   Note that full interop between native and msys2 programs requires a "native"
     Windows shell. "PowerShell" qualifies. "PowerShell ISE" and the way that the
     "MSYS2" system shortcut launch do not. You can tell if things are working by
     launching MSYS2 and running `python` (which, for us is a native windows
     application).
 *   Reportedly, cmder is a good possibility.

 You can also customize you shell, etc. From now on, when we refer to the shell,
 we mean "launch msys2".

 ```shell
 # In MSYS2 shell
 pacman -S patch
 # Customize the path to your home directory if required.
 echo 'export PATH=/c/Users/$USERNAME/scoop/shims:$PATH' >> ~/.bash_profile
 ```

 You are also going to want a few other environment variables. You are welcome to
 configure these however you choose. Adding them to `~/.bash_profile` would look
 like this:

 ```shell
 # Tells Bazel to use clang-cl instead of VS cl.
 export USE_CLANG_CL=1
 # Tells Bazel where the LLVM installation is.
 export BAZEL_LLVM=C:/Users/$USERNAME/scoop/apps/llvm/current
 # This should be automatic, but worth checking.
 export BAZEL_SH=C:/Users/$USERNAME/scoop/apps/msys2/current/usr/bin/bash.exe
 ```

 ## Install the Vulkan SDK

 Some parts of the project link against the Vulkan SDK and require it be
 installed on your system. If you are planning on building these, or see linker
 errors about undefined references to `vk` symbols, download and install the
 Vulkan SDK from https://vulkan.lunarg.com/, and check that the VULKAN_SDK
 environment variable is set when you are building.

 ## Optional: Configure Git

 ### Git SSH

 *   Make sure that the environment variable is set:
     `GIT_SSH=C:/Users/%USERNAME%/scoop/shims/ssh`
 *   Generate SSH Key: `ssh-keygen -t rsa -b 4096 -C "EMAIL@email.com"`
 *   Add `~/.ssh.id_rsa.pub` key to GitHub
 *   Try a test connection `ssh git@github.com`

 ### Other git config options

 ```shell
 # Disable stupid^H^H^H^H^H^H Windows line ending translation
 git config --global core.autocrlf true
 # Configure name and email before commiting anything
 git config --global user.name "MY NAME"
 git config --global user.email "MY EMAIL"
 ```

 ## Clone and Build

 This assumes that we are cloning into `C:\src\ireepub`. Update accordingly for
 your use.

 ### Clone

 Note that if you will be cloning frequently, it can be sped up significantly by
 creating a reference repo and setting
 `IREE_CLONE_ARGS="--reference=/path/to/reference/repo"`. See
 `scripts/git/populate_reference_repo.sh` for further details.

 ```shell
 IREE_CLONE_ARGS=""
 mkdir -p /c/src/ireepub
 cd /c/src/ireepub
 git clone $IREE_CLONE_ARGS https://github.com/google/iree.git iree
 cd iree
 git submodule init
 git submodule update $IREE_CLONE_ARGS --recursive
 ```

 ### Build

 ```shell
 # Run all core tests
 bazel test -k --config=windows iree/...
 ```

 In general, build artifacts will be under the `bazel-bin` directory at the top
 level.

 ## Recommended user.bazelrc

 You can put a user.bazelrc at the root of the repository and it will be ignored
 by git. The recommended contents for Windows are:

 ```
 build --config=windows
 build --disk_cache=c:/bazelcache
 build:debug --compilation_mode=dbg --copt=/O2 --per_file_copt=iree@/Od --strip=never
 ```

 ## Troubleshooting

 ### Bazel and Visual Studio Versions

 In general, the software has only been build with Visual Studio 2019 Build Tools
 and Clang-CL 9.x. Previous versions are known to have incompatibilities in their
 standard libraries. If you have multiple versions of Visual Studio (and/or Build
 Tools) installed, Bazel may auto-detect the wrong one. You can see this by
 adding a `-s` argument to you build command and looking for a "SET INCLUDE="
 line in the log output (to see where it is pointing).

 You can hard-code the version that Bazel selects by setting:
 `BAZEL_VS=C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools`.

 If updating, you will need to `bazel clean` and `bazel shutdown` for changes to
 take effect.

 See
 [this page](https://docs.bazel.build/versions/master/windows.html#build-c-with-msvc)
 for more options.

 If setting up a new machine, it is best to just make sure there is one version.

 ### Caching

 Bazel can use a local disk cache, which can speed up compiles that iterate
 between different sets of flags (ie. optimized and prod). Add this to your
 user.bazelrc:

 ```
 build --disk_cache=c:/bazelcache
 ```

 ### Debugging

 By default, the project builds in opt mode, which is optimized/stripped. For
 Windows builds that do not wish to switch entirely to a debug build (i.e. it is
 often advantageous to only disable optimizations for some part of the code you
 are working on, you can use a build config like this by adding it to your
 user.bazelrc and building with --config=debug):

 ```
 build:debug --compilation_mode=dbg --copt=/O2 --per_file_copt=iree@/Od --strip=never
 ```

 Note that there is a Windows specific sharp edge: The `-O0` flag does nothing on
 CL-like compilers. You must use the Microsoft syntax of /Od. Given that, we just
 use it consistently.

 ## Annex

 ### Configuring Python

 The python bindings are still rudimentary but do require a functioning Python
 install with deps. If you installed Python from scoop or another place that
 doesn't bundle common deps, you'll need to take a couple of extra steps:

 #### Install PIP:

 Try running `pip`. If it doesn't exist (and if it isn't in your python Scripts/
 directory and somehow excluded from your path), install it by:

 ```shell
 which python
 # Verify that this is where you think it is. Also verify that pip
 # prints install paths where you think.
 curl https://bootstrap.pypa.io/get-pip.py > ~/Downloads/get-pip.py
 python ~/Downloads/get-pip.py
 # Note that pip may print a directory name that needs to be added
 # to the path. Do so.
 ```

 #### Install Python Deps

 ```shell
 pip install numpy
 ```

 If using Colab, you may also want to install TensorFlow:

 ```shell
 pip install tf-nightly
 ```
	# Getting Started on Windows

	There are multiple ways to develop on Windows, and compared to other
	environments, batteries are often not included. This document outlines the setup
	that is known to work for the IREE developers. Other setups almost certainly
	work as well.

	## Pre-requisites

	### Enable Developer Mode

	We use symlinks in the build, and this requires developer mode to be enabled:

	* Open Settings
	* Search for "Developer Settings"
	* Select the radio button "Developer mode" and accept all prompts

	### Install Build Tools For Visual Studio

	At the time of writing, this can be found by going to
	[this page](https://visualstudio.microsoft.com/downloads/) and finding the
	Download link for "Build Tools for Visual Studio 2019".

	Minimally select to install "C++ Build Tools".

	### Install the Scoop Package Manager

	The [Scoop page is here](https://scoop.sh/). Follow the instructions at the
	bottom.

	IMPORTANT: When launching PowerShell, make sure to not select any option that
	ends in "(x86)" as this will install the 32bit version, and all of the software
	that Scoop installs will be 32bit. While 32bit builds of the project may be
	possible, we only (presently) support 64bit. Also, not all packages are
	available in 32bit.

	## Install Scoop Packages

	### Home Directory

	Optional: Set the msys2 home directory to your Windows home directory. By
	default, the msys2 HOME will be nested inside the installation directory, which
	is managed by scoop and somewhat ephemeral.

	* Open the Windows environment dialog (This PC -> Properties -> Advanced
	Settings -> Environment Variables...)
	* Add a new User variable: `HOME` = `C:\Users\%USERNAME%` (replacing with the
	actual location of your Windows home directory).
	* Ok out of all dialogs
	* Restart PowerShell
	* Verify that it took effect (`Get-ChildItem Env:HOME`)

	While here, also consider adding `GIT_SSH=C:/Users/%USERNAME%/scoop/shims/ssh`
	which will help git find the right SSH and keys (you probably want this as a
	global to Windows vs just in your shell, which is why it is recommended here).

	### Scoop Package Setup

	In PowerShell, run the following:

	```shell
	scoop install git nano vim
	scoop bucket add extras
	scoop bucket add versions
	scoop install msys2
	scoop install curl cmake openssh python36 llvm bazel
	# Optional
	scoop install vscode
	```

	TODO: Upgrade to head python.

	Check the .bazelversion file for the version of Bazel you should install. You
	can also use [Bazelisk](https://github.com/bazelbuild/bazelisk) to manage Bazel
	versions.

	TODO: Specific steps to install a compatible version of Bazel directly

	## Setup MSYS2

	Then run msys2 for the first time for subsequent setup by doing one of:

	* Launch MSYS2 from the start menu
	* From a regular PowerShell terminal (not ISE, which hangs), run `msys2`
	* Note that full interop between native and msys2 programs requires a "native"
	Windows shell. "PowerShell" qualifies. "PowerShell ISE" and the way that the
	"MSYS2" system shortcut launch do not. You can tell if things are working by
	launching MSYS2 and running `python` (which, for us is a native windows
	application).
	* Reportedly, cmder is a good possibility.

	You can also customize you shell, etc. From now on, when we refer to the shell,
	we mean "launch msys2".

	```shell
	# In MSYS2 shell
	pacman -S patch
	# Customize the path to your home directory if required.
	echo 'export PATH=/c/Users/$USERNAME/scoop/shims:$PATH' >> ~/.bash_profile
	```

	You are also going to want a few other environment variables. You are welcome to
	configure these however you choose. Adding them to `~/.bash_profile` would look
	like this:

	```shell
	# Tells Bazel to use clang-cl instead of VS cl.
	export USE_CLANG_CL=1
	# Tells Bazel where the LLVM installation is.
	export BAZEL_LLVM=C:/Users/$USERNAME/scoop/apps/llvm/current
	# This should be automatic, but worth checking.
	export BAZEL_SH=C:/Users/$USERNAME/scoop/apps/msys2/current/usr/bin/bash.exe
	```

	## Install the Vulkan SDK

	Some parts of the project link against the Vulkan SDK and require it be
	installed on your system. If you are planning on building these, or see linker
	errors about undefined references to `vk` symbols, download and install the
	Vulkan SDK from https://vulkan.lunarg.com/, and check that the VULKAN_SDK
	environment variable is set when you are building.

	## Optional: Configure Git

	### Git SSH

	* Make sure that the environment variable is set:
	`GIT_SSH=C:/Users/%USERNAME%/scoop/shims/ssh`
	* Generate SSH Key: `ssh-keygen -t rsa -b 4096 -C "EMAIL@email.com"`
	* Add `~/.ssh.id_rsa.pub` key to GitHub
	* Try a test connection `ssh git@github.com`

	### Other git config options

	```shell
	# Disable stupid^H^H^H^H^H^H Windows line ending translation
	git config --global core.autocrlf true
	# Configure name and email before commiting anything
	git config --global user.name "MY NAME"
	git config --global user.email "MY EMAIL"
	```

	## Clone and Build

	This assumes that we are cloning into `C:\src\ireepub`. Update accordingly for
	your use.

	### Clone

	Note that if you will be cloning frequently, it can be sped up significantly by
	creating a reference repo and setting
	`IREE_CLONE_ARGS="--reference=/path/to/reference/repo"`. See
	`scripts/git/populate_reference_repo.sh` for further details.

	```shell
	IREE_CLONE_ARGS=""
	mkdir -p /c/src/ireepub
	cd /c/src/ireepub
	git clone $IREE_CLONE_ARGS https://github.com/google/iree.git iree
	cd iree
	git submodule init
	git submodule update $IREE_CLONE_ARGS --recursive
	```

	### Build

	```shell
	# Run all core tests
	bazel test -k --config=windows iree/...
	```

	In general, build artifacts will be under the `bazel-bin` directory at the top
	level.

	## Recommended user.bazelrc

	You can put a user.bazelrc at the root of the repository and it will be ignored
	by git. The recommended contents for Windows are:

	```
	build --config=windows
	build --disk_cache=c:/bazelcache
	build:debug --compilation_mode=dbg --copt=/O2 --per_file_copt=iree@/Od --strip=never
	```

	## Troubleshooting

	### Bazel and Visual Studio Versions

	In general, the software has only been build with Visual Studio 2019 Build Tools
	and Clang-CL 9.x. Previous versions are known to have incompatibilities in their
	standard libraries. If you have multiple versions of Visual Studio (and/or Build
	Tools) installed, Bazel may auto-detect the wrong one. You can see this by
	adding a `-s` argument to you build command and looking for a "SET INCLUDE="
	line in the log output (to see where it is pointing).

	You can hard-code the version that Bazel selects by setting:
	`BAZEL_VS=C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools`.

	If updating, you will need to `bazel clean` and `bazel shutdown` for changes to
	take effect.

	See
	[this page](https://docs.bazel.build/versions/master/windows.html#build-c-with-msvc)
	for more options.

	If setting up a new machine, it is best to just make sure there is one version.

	### Caching

	Bazel can use a local disk cache, which can speed up compiles that iterate
	between different sets of flags (ie. optimized and prod). Add this to your
	user.bazelrc:

	```
	build --disk_cache=c:/bazelcache
	```

	### Debugging

	By default, the project builds in opt mode, which is optimized/stripped. For
	Windows builds that do not wish to switch entirely to a debug build (i.e. it is
	often advantageous to only disable optimizations for some part of the code you
	are working on, you can use a build config like this by adding it to your
	user.bazelrc and building with --config=debug):

	```
	build:debug --compilation_mode=dbg --copt=/O2 --per_file_copt=iree@/Od --strip=never
	```

	Note that there is a Windows specific sharp edge: The `-O0` flag does nothing on
	CL-like compilers. You must use the Microsoft syntax of /Od. Given that, we just
	use it consistently.

	## Annex

	### Configuring Python

	The python bindings are still rudimentary but do require a functioning Python
	install with deps. If you installed Python from scoop or another place that
	doesn't bundle common deps, you'll need to take a couple of extra steps:

	#### Install PIP:

	Try running `pip`. If it doesn't exist (and if it isn't in your python Scripts/
	directory and somehow excluded from your path), install it by:

	```shell
	which python
	# Verify that this is where you think it is. Also verify that pip
	# prints install paths where you think.
	curl https://bootstrap.pypa.io/get-pip.py > ~/Downloads/get-pip.py
	python ~/Downloads/get-pip.py
	# Note that pip may print a directory name that needs to be added
	# to the path. Do so.
	```

	#### Install Python Deps

	```shell
	pip install numpy
	```

	If using Colab, you may also want to install TensorFlow:

	```shell
	pip install tf-nightly
	```