Revert "HLSL: force FXC to never unroll loops"

This reverts commit 11d09f2fe7c006b78f7319e876e4ced43f0c1a60.

Reason for revert: Failing roll of Tint to Dawn:

Original change's description:
> HLSL: force FXC to never unroll loops
> Emit the "[loop]" attribute on "for" and "while" so that FXC does not
> attempt to unroll them. This is to work around an FXC bug where it fails
> to unroll loops with gradient operations.
> FXC ostensibly unrolls such loops because gradient operations require
> uniform control flow, and loops that have varying iterations may
> possibly not be uniform. Tint will eventually validate that control flow
> is indeed uniform, so forcing FXC to avoid unrolling in these cases
> should be fine.
> Bug: tint:1112
> Change-Id: I10077f8b62fbbb230a0003f3864c75a8fe0e1d18
> Reviewed-on:
> Kokoro: Kokoro <>
> Reviewed-by: Ben Clayton <>
> Commit-Queue: Antonio Maiorano <>

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: tint:1112
Change-Id: I8e8f3c0abfa6e6bc5d0e67af9428a46ef867d5c1
Reviewed-by: Antonio Maiorano <>
Reviewed-by: Ben Clayton <>
Kokoro: Kokoro <>
Commit-Queue: Antonio Maiorano <>
49 files changed
tree: 463c6e7fa4cb9935f74c7f43838592c6079d5f56
  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.