Dawn bindings for NodeJS

Note: This code is currently WIP. There are a number of known issues.

Building

System requirements

CMake 3.10 or greater
Go 1.13 or greater

Install `depot_tools`

Dawn uses the Chromium build system and dependency management so you need to install depot_tools and add it to the PATH.

Fetch dependencies

First, the steps are similar to doc/building.md, but instead of the Get the code step, run:

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

# Bootstrap the NodeJS binding gclient configuration
cp scripts/standalone-with-node.gclient .gclient

# Fetch external dependencies and toolchains with gclient
gclient sync

Build

Currently, the node bindings can only be built with CMake:

mkdir <build-output-path>
cd <build-output-path>
cmake <dawn-root-path> -GNinja -DDAWN_BUILD_NODE_BINDINGS=1 -DDAWN_ENABLE_PIC=1
ninja dawn.node

Running WebGPU CTS

Build the dawn.node NodeJS module.
Checkout the WebGPU CTS repo

./src/dawn_node/tools/run-cts --cts=<path-to-webgpu-cts> --dawn-node=<path-to-dawn.node> [WebGPU CTS query]

If this fails with the error message TypeError: expander is not a function or its return value is not iterable, try appending --build=false to the start of the run-cts command line flags.

To test against SwiftShader instead of the default Vulkan device, prefix ./src/dawn_node/tools/run-cts with VK_ICD_FILENAMES=<swiftshader-cmake-build>/Linux/vk_swiftshader_icd.json

Known issues

Many WebGPU CTS tests are currently known to fail
Dawn uses special token values for some parameters / fields. These are currently passed straight through to dawn from the JavaScript. discussions: 1, 2, 3
Backend validation is currently always set to ‘full’ to aid in debugging. This can be extremely slow. discussion
Attempting to call new T in JavaScript, where T is an IDL interface type, should result in a TypeError “Illegal constructor”. discussion
GPUDevice currently maintains a list of “lost promises”. This should return the same promise. discussion

Remaining work

Have the IDL interop generator produce default values for parameters (instead of std::optional). discussion
Investigate CTS failures that are not expected to fail.
Generated includes live in src/ for dawn_node, but outside for Dawn. discussion
Hook up to presubmit bots (CQ / Kokoro)
binding::GPU will require significant rework once Dawn implements the device / adapter creation path properly.