GLSL: fix textureLoad() and textureStore(), depth textures, and more.

The CombineSamplers transform was incorrectly flagging StorageTexture
(which in GLSL ends up as image2D) as needing to be combined with a
sampler, or at least renamed. This is incorrect: StorageTexture never
has an associated sampler, so don't try to pair it up and just output
it as image* in GLSL.

In GLSL, textureLoad (aka texelFetch) of depth textures is not allowed.
The fix is to bind the depth texture as the corresponding f32 texture
instead (e.g., texture_depth_2d -> texture_2d<f32>,
texture_depth_cube -> texture_cube<f32>, etc). This requires changing
both the uniform globals and function parameter types. We're now going
to receive a vec4 instead of a float from texelFetch, so add a ".x"
member accessor to retrieve the first component. (Note that we don't
do this inside a CallStatement since this gives the CloneContext
indigestion, and CallStatement is going to ignore the result of the
call anyway.)

We were failing to find the dummy samplers that Dawn creates for the
calls that actually do require a dummy sampler, since the old Inspector
implementation of GetSamplerTextureUses() does not find them. The fix
is to implement a new Inspector call to return the texture/sampler
pairs the Resolver found during resolution. This will include the
dummy sampler as a null variable pointer.

In order to identify the placeholder sampler, we pass in a BindingPair
to represent it. When we discover a null sampler in the variable pair,
we return the passed-in placeholder binding point to the caller (Dawn).
(Dawn will use a group of kMaxBindGroups, to ensure that it never
collides with an existing sampler.)

Bug: tint:1298
Change-Id: I82e142c2b4318608c27a9fa9521c27f15a6214cd
Reviewed-by: Ben Clayton <>
Kokoro: Kokoro <>
Commit-Queue: Stephen White <>
195 files changed
tree: 49e08d200d12d70d6a76d06bbb5210454f194a39
  1. .vscode/
  2. build_overrides/
  3. docs/
  4. fuzzers/
  5. include/
  6. infra/
  7. kokoro/
  8. samples/
  9. src/
  10. test/
  11. third_party/
  12. tools/
  13. .clang-format
  14. .gitignore
  15. .gn
  18. CMakeLists.txt
  19. CMakeSettings.json
  22. CPPLINT.cfg
  23. DEPS
  24. Doxyfile
  26. OWNERS
  29. standalone.gclient
  30. tint_overrides_with_defaults.gni


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

This is not an officially supported Google product.


  • 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)


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 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/

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


Please file any issues or feature requests at


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

Tint has a process for supporting experimental extensions.