[tools] Allow precompiling gen_kernel and compile_platform

When iterating on core library changes or changes in the AOT compiler
many seconds are wasted waiting on gen_kernel/compile_platform to
parse Dart code. This happens because we are running these tools
from sources on prebuilt Dart SDK.

This CL allows SDK developer to opt-in into AOT compiling these
tools by adding `precompile_tools=true` to their DART_GN_ARGS.

AOT compilation is performed using prebuilt SDK - so these
executables do not need to be recompiled if core libraries or
VM changes reducing iteration cycles.

pkg/vm/tool/precompiler2 is tweaked to detect when DART_GN_ARGS
contains `precompile_tools=true` and use precompiled
gen_kernel.exe instead of running it from source.

Using precompiled compile_platform takes vm_platform_strong.dill
build from 20 seconds to 3 seconds.

Using precompiled gen_kernel takes small benchmark build from
~10 seconds to 2 seconds.

This relands 5cda2a871cf274a1943e56e208634055ea996598 with fixes
for Flutter build.

TEST=manually tested

Change-Id: I552861c80c152890655e41baaf6ea3fb3b03a57e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/367961
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
7 files changed
tree: f7804d090ee82d1153aa6ada3a56cf2c2058c2d7
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .style.yapf
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  26. DEPS
  28. OWNERS
  30. PRESUBMIT.py
  31. README.dart-sdk
  32. README.md
  33. sdk.code-workspace
  34. sdk_args.gni
  35. sdk_packages.yaml
  36. SECURITY.md


An approachable, portable, and productive language for high-quality apps on any platform

Dart is:

  • Approachable: Develop with a strongly typed programming language that is consistent, concise, and offers modern language features like null safety and patterns.

  • Portable: Compile to ARM, x64, or RISC-V machine code for mobile, desktop, and backend. Compile to JavaScript or WebAssembly for the web.

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app. Diagnose app issues using DevTools.

Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

Dart platforms illustration

License & patents

Dart is free and open source.


Using Dart

Visit dart.dev to learn more about the language, tools, and to find codelabs.

Browse pub.dev for more packages and libraries contributed by the community and the Dart team.

Our API reference documentation is published at api.dart.dev, based on the stable release. (We also publish docs from our beta and dev channels, as well as from the primary development branch).

Building Dart

If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.

There are more documents in our repo at docs.

Contributing to Dart

The easiest way to contribute to Dart is to file issues.

You can also contribute patches, as described in Contributing.


Future plans for Dart are included in the combined Dart and Flutter roadmap on the Flutter wiki.