Flow analysis: prepare for rework of `promotionInfo` data structure.

`FlowModel.promotionInfo` is currently a map from integer promotion
keys to PromotionModel data structures. This is inefficient because
FlowModel is an immutable data structure, so whenever the promotion
state of a variable changes, the map must be duplicated. In a
follow-up CL I will be changing `FlowModel.promotionInfo` to a much
more efficient data structure. However, that data structure will
require some extra plumbing. For ease in code review, I'm doing the
extra plumbing first, as its own CL.

This CL makes the following changes:

- Removes unnecessary null checks from the `FlowModel.withInfo`
  constructor. These null checks are no longer needed because all the
  clients of flow analysis are now fully null safe. This change is not
  strictly necessary; it's just a long-overdue clean-up.

- Adds a `helper` argument (of type `FlowAnalysisHelper`) to
  `FlowModel.conservativeJoin`, `FlowModel.declare`, and
  `FlowModel.infoFor`, `FlowModel.inheritTested`, and
  `FlowModel._updatePromotionInfo`. This is needed because these
  methods will need access to `FlowAnalysisHelper` in order to read
  and update the new data structure.

- Removes the `typeOperations` argument of `FlowModel.inheritTested`,
  since it can be easily obtained from the new `helper` argument.

- Changes `FlowModel._updatePromotionInfo` to a public method
  annotated with `@visibleForTesting`. This will be needed by flow
  analysis unit tests to create the new data structure.

Note that this change causes a small regression in the performance of
CFE compilation, due to the extra `helper` arguments:

    instructions:u: 0.0693% +/- 0.0008% (13413234.33 +/- 155671.09)
    branches:u: 0.0886% +/- 0.0012% (3502620.67 +/- 45724.97)

The follow-up CL that switches to a more efficient data structure will
result in a performance improvement roughly an order of magnitude
larger.

Change-Id: I21c13fb817f05281b558f0473119473a26ea0fb8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/326860
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
2 files changed
tree: fa2b4f83d4cc1d2d8e58c42af9bbb512acffc43c
  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.