[dart2wasm] Add deferred loading support to dart2wasm (2/X).

Add deferred loading analysis and constructs to dart2wasm. This does a library-level analysis of the program's import structure and generates a graph of the imports. If a set of libraries is shared between two deferred units, those libraries will all be added to a distinct module. A `loadLibrary` call would then trigger a load of all the modules needed for that import.

When the 'enable-deferred-loading' flag is disabled, all libraries are trivially added to the main module preserving current behavior.

Uses `Reference`s as the module assignment mechanism. For References that come from the kernel, we can find the enclosing library of the attached `NamedNode` to determine which module it belongs to. For code synthesized by the compiler we provide a mechanism (`createSyntheticReference`) to create a Reference attached to a specific module. This same mechanism can be used to label any module-specific entity.

The deferred loading graph analysis differs from the Dart2js analysis in that we are assigning modules at the library level rather than at the member level.

It differs from the VM analysis in that it also tracks which load units are needed for each deferred import. The VM analysis assigns load units but it does not track which load units are needed for a given deferred import.

My goal is to reuse this same ModuleOutput API for dynamic modules and have the rest of the compiler work correctly given this common API.

Change-Id: Ibd3a49ad555f3818fa4fda4d846e7883b55eef33
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/379901
Reviewed-by: Martin Kustermann <kustermann@google.com>
4 files changed
tree: ece161b3805caff7e499fb88b7d749280f01ddc7
  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
  21. AUTHORS
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  25. CONTRIBUTING.md
  26. DEPS
  27. LICENSE
  28. OWNERS
  29. PATENT_GRANT
  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
  37. WATCHLISTS
README.md

Dart

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.

See LICENSE and PATENT_GRANT.

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.

Roadmap

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