[vm, gc] Add write-write fence after initializing object headers, or defer marking new-space objects in an active TLAB.

On architectures with a weak memory model, there is the possibility that the concurrent marker can see the publishing store of a new object before it sees the initializing store of that object's header. On an M1, the barrier to prevent reordering these stores is fairly cheap, so we emit this barrier on Mac/iOS ARM64. Otherwise, this barrier is very expensive (or at least expensive for some hardware within the ABI), so instead we avoid the race by deferring marking of objects inside an active TLAB.

Disable TSAN instrumentation on the marker setting the mark bit, as TSAN does not understand fences.

TEST=ooo arm64 machines
Bug: https://github.com/dart-lang/sdk/issues/56845
Change-Id: I0676661a7cf941fdc6b451e516d890c26826bb3b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389265
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
31 files changed
tree: d7c27b1a6a051896f05d14e0dccbee3db3eb8f72
  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.