| commit | f2ee7ba7a437c2f3f61a3c55cbe68c054ea80e81 | [log] [tgz] |
|---|---|---|
| author | Ömer Ağacan <omersa@google.com> | Tue Apr 15 02:41:05 2025 -0700 |
| committer | dart-internal-monorepo <dart-internal-monorepo@dart-ci-internal.iam.gserviceaccount.com> | Tue Apr 15 02:43:39 2025 -0700 |
| tree | 95be213f60ad07561ea8b251898e6fe9cdf3e450 | |
| parent | 8ec5841e9b7083797e00cb0a7baba9538f15141f [diff] |
[dart2wasm] Convert simple async function bodies to sync `Future.value` calls
This transforms functions like
async foo() => const ...;
to
foo() => Future.value(const ...);
The transformation is done when the async function body is a `const`
expression or a basic literal (string, int, double, bool).
These expressions don't have side effects and they cannot throw, so it's
safe to convert them to `Future.value`s.
This makes the generated code in the ACX demo 2.5% smaller: (`-O4` with
symbol names removed)
- Before: 9,040,020 bytes
- After: 8,805,471 bytes
- Diff: -234,549 bytes, -2.59%
With this we also remove the same special case in the backend to avoid
generating a state machine for these functions, as the special case
handled before the backend now and backend never sees this kind of
functions.
(Technically with inlining or other backend optimizations it could still
see these cases, but the pattern it matches is too strict, and currently
the special case in the backend doesn't do anything on the ACX demo.)
Note: I tried implementing the same in dart2js's await lowering pass in
https://dart-review.googlesource.com/c/sdk/+/422061 and reusing that
pass in https://dart-review.googlesource.com/c/sdk/+/420140.
However while that transformed simple programs as expected, in ACX demo
it still introduced a lot of `Future.sync` calls and made the overall
binary larger. I think we never want to introduce `Future.sync` calls
(at least until we improve code size for closures, see relevant issue
https://github.com/dart-lang/sdk/issues/60458), so for now we don't
reuse dart2js's pass.
Issue: https://github.com/dart-lang/sdk/issues/60433
Change-Id: I206ac8c6081201041f67e7fc91776077e52180a0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/422120
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Ömer Ağacan <omersa@google.com>
https://dart.googlesource.com/sdk/+/e4676d5b5690220996191357064c1137e4990a09
Monorepo is:
With depot_tools installed and on your path, create a directory for your monorepo checkout and run these commands to create a gclient solution in that directory:
mkdir monorepo cd monorepo gclient config --unmanaged https://dart.googlesource.com/monorepo gclient sync -D
This gives you a checkout in the monorepo directory that contains:
monorepo/ DEPS - the DEPS used for this gclient checkout commits.json - the pinned commits for Dart, flutter/engine, and flutter/flutter tools/ - scripts used to create monorepo DEPS engine/src/ - the flutter/buildroot repo flutter/ - the flutter/engine repo out/ - the build directory, where Flutter engine builds are created third_party/ - Flutter dependencies checked out by DEPS dart/ - the Dart SDK checkout. third_party - Dart dependencies, also used by Flutter flutter/ - the flutter/flutter repo
Flutter's instructions for building the engine are at Compiling the engine
They can be followed closely, with a few changes:
goma_ctl ensure_start is sufficient.Example build commands that work on linux:
MONOREPO_PATH=$PWD if [[ ! $PATH =~ (^|:)$MONOREPO_PATH/flutter/bin(:|$) ]]; then PATH=$MONOREPO_PATH/flutter/bin:$PATH fi export GOMA_DIR=$(dirname $(command -v gclient))/.cipd_bin goma_ctl ensure_start pushd engine/src flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk autoninja -C out/host_debug_unopt popd
The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.
For example, to build and run the Flutter spinning square sample on the web platform,
MONOREPO_PATH=$PWD cd flutter/examples/layers flutter --local-engine=host_debug_unopt \ -d chrome run widgets/spinning_square.dart cd $MONOREPO_PATH
To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command
flutter create --platforms=windows,macos,linux
on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter
Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:
MONOREPO_PATH=$PWD cd flutter/packages/flutter flutter test --local-engine=host_debug_unopt cd $MONOREPO_PATH
Please file an issue or email the dart-engprod team with any problems with or questions about using monorepo.
We will update this documentation to address them.
flutter commands may download the engine and Dart SDK files for the configured channel, even though they will be using the local engine and its SDK.gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.