Dawn, a WebGPU implementation

Dawn is an open-source and cross-platform implementation of the work-in-progress WebGPU standard. More precisely it implements webgpu.h that is a one-to-one mapping with the WebGPU IDL. Dawn is meant to be integrated as part of a larger system and is the underlying implementation of WebGPU in Chromium.

Dawn provides several WebGPU building blocks:

• WebGPU C/C++ headers that applications and other building blocks use.
  • The webgpu.h version that Dawn implements.
  • A C++ wrapper for the webgpu.h.
• A "native" implementation of WebGPU using platforms' GPU APIs:
  • D3D12 on Windows 10
  • Metal on macOS and iOS
  • Vulkan on Windows, Linux, ChromeOS, Android and Fuchsia
  • OpenGL as best effort where available
• A client-server implementation of WebGPU for applications that are in a sandbox without access to native drivers

Helpful links:

• Dawn's bug tracker if you find issues with Dawn.
• Dawn's mailing list for other discussions related to Dawn.
• Dawn's source code
• Dawn's Matrix chatroom for live discussion around contributing or using Dawn.
• WebGPU's Matrix chatroom

Documentation table of content

Developer documentation:

• Dawn overview
• Building Dawn
• Contributing to Dawn
• Testing Dawn
• Debugging Dawn
• Dawn's infrastructure
• Dawn errors

User documentation: (TODO, figure out what overlaps with the webgpu.h docs)

Status

(TODO)

License

Apache 2.0 Public License, please see LICENSE.

Disclaimer

This is not an officially supported Google product.

Tint

Tint is a compiler for the WebGPU Shader Language (WGSL).

This is not an officially supported Google product.

Requirements

• Git
• CMake (3.10.2 or later)
• Ninja (or other build tool)
• Python, for fetching dependencies
• depot_tools in your path

Build options

• TINT_BUILD_SPV_READER : enable the SPIR-V input reader (off by default)
• TINT_BUILD_WGSL_READER : enable the WGSL input reader (on by default)
• TINT_BUILD_SPV_WRITER : enable the SPIR-V output writer (on by default)
• TINT_BUILD_WGSL_WRITER : enable the WGSL output writer (on by default)
• TINT_BUILD_FUZZERS : enable building fuzzzers (off by default)

Building

Tint uses Chromium dependency management so you need to install depot_tools and add it to your PATH.

Getting source & dependencies

# Clone the repo as "tint"
git clone https://dawn.googlesource.com/tint tint
cd tint

# Bootstrap the gclient configuration
cp standalone.gclient .gclient

# Fetch external dependencies and toolchains with gclient
gclient sync

Compiling using CMake + Ninja

mkdir -p out/Debug
cd out/Debug
cmake -GNinja ../..
ninja # or autoninja

Compiling using CMake + make

mkdir -p out/Debug
cd out/Debug
cmake ../..
make # -j N for N-way parallel build

Compiling using gn + ninja

mkdir -p out/Debug
gn gen out/Debug
autoninja -C out/Debug

Fuzzers on MacOS

If you are attempting fuzz, using TINT_BUILD_FUZZERS=ON, the version of llvm in the XCode SDK does not have the needed libfuzzer functionality included.

The build error that you will see from using the XCode SDK will look something like this:

ld: file not found:/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.0/lib/darwin/libclang_rt.fuzzer_osx.a

The solution to this problem is to use a full version llvm, like what you would get via homebrew, brew install llvm, and use something like CC=<path to full clang> cmake .. to setup a build using that toolchain.

Checking [chromium-style] issues in CMake builds

The gn based work flow uses the Chromium toolchain for building in anticipation of integration of Tint into Chromium based projects. This toolchain has additional plugins for checking for style issues, which are marked with [chromium-style] in log messages. This means that this toolchain is more strict then the default clang toolchain.

In the future we will have a CQ that will build this work flow and flag issues automatically. Until that is in place, to avoid causing breakages you can run the [chromium-style] checks using the CMake based work flows. This requires setting CC to the version of clang checked out by gclient sync and setting the TINT_CHECK_CHROMIUM_STYLE to ON.

mkdir -p out/style
cd out/style
cmake ../..
CC=../../third_party/llvm-build/Release+Asserts/bin/clang cmake -DTINT_CHECK_CHROMIUM_STYLE=ON ../../ # add -GNinja for ninja builds

Issues

Please file any issues or feature requests at https://bugs.chromium.org/p/tint/issues/entry

Contributing

Please see the CONTRIBUTING and CODE_OF_CONDUCT files on how to contribute to Tint.

Tint has a process for supporting experimental extensions.