commit 11784009dbbfcbca5f321e2c7ce28b15eabcb151
author Kai Ninomiya <kainino@chromium.org> Wed Jul 03 19:46:03 2024 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Jul 03 19:46:03 2024 +0000
tree 3d7cbc2e06166c72c3dfab0bc3f7ac39e74b9395
parent a10fbeac3c40b94771587c093c5b2999836c49c8

Generate files to use Emscripten bindings from outside Emscripten

We are stabilizing webgpu.h, and that process requires many (mostly
small) breaking changes to the header. Right now, some projects are
relying on Emscripten's and Dawn's implementations of webgpu.h to be in
sync, but this creates challenges because we need to make many separate
breaking changes.

This change forks Emscripten's WebGPU bindings into Dawn (in
//third_party) in such a way that they don't have to be checked into the
Emscripten repository. This way we can keep Dawn's bindings and Dawn's
fork of the Emscripten bindings in sync (approximately) in the Dawn
repository.

Projects depending on Emscripten and Dawn to be in sync should use this
fork instead, until we've finished the webgpu.h changes and contributed
the bindings back up to Emscripten in one big breaking release that
should have minimal to no breakage afterward.

For ease of diffing this commit overwrites the verbatim copies of
library_{,html5_}webgpu.js added in the previous commit, with a few
updates to bring it in sync with Dawn (though it may not be fully in
sync - it has only been minimally tested so far).

Example of using the resulting generated files from outside GN:
https://github.com/kainino0x/webgpu-cross-platform-demo/compare/dawnwasm

The generated files can only be generated using the GN build; CMake
rules haven't been implemented, and the existing Emscripten build rules
for CMake have been removed.

Note, since these bindings were designed to live inside Emscripten, they
rely on some Emscripten internals.

Symbols in rough order from less stable to more stable:

- `$stackSave` - changed recently
- `$stackRestore` - changed recently
- `$callUserCallback`
- `$stringToUTF8OnStack`
- `$stringToNewUTF8`
- `$stringToUTF8`
- `$lengthBytesUTF8`
- `$readI53FromI64`
- `$findCanvasEventTarget`
- `$warnOnce`

Generator internals, these seem stable:

- `mergeInto`
- `C_STRUCTS`
- `LibraryManager.library`

The build rules also depend on:

- the location of `gen_struct_info.py` (which recently changed from
  `tools/` to `tools/maint/`)

Bug: 346806934
Change-Id: I6ca10ea37bc7307d4d9571dcdc696e7d025663d3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/193722
Reviewed-by: Loko Kung <lokokung@google.com>
Auto-Submit: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>