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This CL adds in fuzzers for SPIRV-Cross for HLSL, GLSL, and MSL outputs. These fuzzers live in Dawn because there is not appropriate location in the Chromium source repo for them and it is unlikely they would be land-able in the SPIRV-Cross repo, because it is not coupled with Chromium's build system and thus Clusterfuzz so would be effectively dead code. Dawn depends on this code, but it is also integrated into the Chromium build system, so this was the best place I could find for them The code under fuzz unfortunately uses exceptions/aborting as its error reporting mechanism. This is an acknowledge short coming and there are efforts to remove this behaviour. To work around this and reduce the number of false positives found by the fuzzers, a signal trap has been implemented which will be removed once the code under fuzz has been updated. The trap replaces the existing signal handler and silencing signals while running the code under test. This allows the code under test to call abort() and not crash the fuzzing process. Theoretically, only SIGABRT should need to be trapped, but something is causing the signal from abort() to be converted to SIGSEGV when running under ASAN. This signal trap has been tested with the fuzzing/sanitizers by intentionally inserting bad calls that will occur after a few thousand test cases. It was confirmed that the fuzzer detected the issue and stops fuzzing. The alternate to implementing this signal trap would be to turn on exceptions for the fuzzer. This was attempted, but proved to be fruitless due to what was reported as an ODR issue, but couldn't couldn't be silenced. The likely underlying issue was a pre-built library or other object being built without exceptions was causing different versions of symbols or the exception version of the standard library not being instrumented by ASAN. Given the majority of Chromium eco-system turns off exceptions, fixing this issue would not be helpful to the larger community and was looking like it would require significant effort. BUG=chromium:903380 Change-Id: I63a5595383f99b7a0e150d72bb04c89b8d722631 Reviewed-on: https://dawn-review.googlesource.com/c/2260 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Max Moroz <mmoroz@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Dawn, a WebGPU implementation
Dawn (formerly NXT) is an open-source and cross-platform implementation of the work-in-progress WebGPU standard. It exposes a C/C++ API that maps almost one-to-one to the WebGPU IDL and can be managed as part of a larger system such as a Web browser.
Dawn provides several WebGPU building blocks:
- WebGPU C/C++ headers that applications and other building blocks use.
- A "native" implementation of WebGPU using platforms' GPU APIs:
- D3D12 on Windows 10
- Metal on OSX (and eventually iOS)
- Vulkan on Windows, Linux (eventually ChromeOS and Android too)
- OpenGL as best effort where available
- A client-server implementation of WebGPU for applications that are in a sandbox without access to native drivers
Directory structure
dawn.json: description of the API used to drive code generators.examples: examples showing how Dawn is used.generator: code generator for files produces fromdawn.jsontemplates: Jinja2 templates for the generator
scripts: scripts to support things like continuous testing, build files, etc.src:common: helper code shared between core Dawn libraries and tests/samplesdawn_native: native implementation of WebGPU, one subfolder per backenddawn_wire: client-server implementation of WebGPUinclude: public headers for Dawntests: internal Dawn testsend2end: WebGPU tests performing GPU operationsunittests: unittests and by extension tests not using the GPUvalidation: WebGPU validation tests not using the GPU (frontend tests)
utils: helper code to use Dawn used by tests and samples
third_party: directory where dependencies live as well as their buildfiles.
Building Dawn
Dawn uses the Chromium build system and dependency management so you need to [install depot_tools] and add it to the PATH. Then get the source as follows:
# Clone the repo as "dawn"
git clone https://dawn.googlesource.com/dawn dawn && cd dawn
# Bootstrap the gclient configuration
cp scripts/standalone.gclient .gclient
# Fetch external dependencies and toolchains with gclient
gclient sync
Then generate build files using gn args out/Debug or gn args out/Release.
A text editor will appear asking build options, the most common option is is_debug=true/false; otherwise gn args out/Release --list shows all the possible options.
Then use ninja -C out/Release to build dawn and for example ./out/Release/dawn_end2end_tests to run the tests.
Contributing
Please read and follow CONTRIBUTING.md. Dawn doesn't have a formal coding style yet, except what's defined by our clang format style. Overall try to use the same style and convention as code around your change.
If you find issues with Dawn, please feel free to report them on the bug tracker.
License
Please see LICENSE.
Disclaimer
This is not an officially supported Google product.