[dart2js] Evaluate CFE consts as part of phase 0b (CFE linker).

Constants are current evaluated in a few places during closed world generation, primarily as part of the ScopeModelBuilder. The scope visitor was modifying the AST which meant we had to emit a new dill with these evaluated constants along with the closed world results.

This change instead evaluates the constants directly after linking the Kernel as part of the global transformations. This means we can update the ScopeModelBuilder to not mutate the AST at all as all constants are already simplified.

A potential follow up here is to simplify the ScopeModelBuilder since all nodes should already be simplified if they can be, we should be able to avoid visiting some children.

After this change we only directly create a single ConstantEvaluator, the one in `load_kernel`. The const simplifier also creates one and a follow up CL moves this to to run right after this new transformation.

Note: Alternate versions of this CL tried to make the global transformation simpler by either:
1) Running the const evaluator indiscriminately on all expressions. This didn't work because it lead to exponential computation on constants set up as a DAG (see tests/language/const/constant_dag_test).
2) Only evaluating ConstantExpression nodes to update UnevaluatedConstants. This does not cover all the cases where the ScopeModelBuilder is modifying the tree and lead to a different compiler output.

Change-Id: I746d889b37feddc9ab6c386c6252016dec745e6e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/332601
Reviewed-by: Mayank Patke <fishythefish@google.com>
23 files changed
tree: 622e1e58baff9451131ad170cf79cf60c9deb308
  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. .vpython
  22. AUTHORS
  23. BUILD.gn
  24. CHANGELOG.md
  25. codereview.settings
  26. CONTRIBUTING.md
  27. DEPS
  28. LICENSE
  29. OWNERS
  30. PATENT_GRANT
  31. PRESUBMIT.py
  32. README.dart-sdk
  33. README.md
  34. sdk.code-workspace
  35. sdk_args.gni
  36. SECURITY.md
  37. WATCHLISTS
README.md

Dart

A client-optimized language for fast apps on any platform

Dart is:

  • Optimized for UI: Develop with a programming language specialized around the needs of user interface creation.

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

  • Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web.

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 on our wiki.

Contributing to Dart

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

You can also contribute patches, as described in Contributing.