[vm, compiler] Specialize unoptimized monomorphic and megamorphic calls.

dart-bytecode, arm64:            +4.742% geomean
dart-bytecode-jit-unopt, arm64: +12.73% geomean
dart2js-compile, x64:            +3.635% geomean

In the polymorphic and unlinked cases, call to a stub the does a linear scan against an ICData.

In the monomorphic case, call to a prologue of the expected target function that checks the expected receiver class. There is additional indirection in the JIT version compared to the AOT version to also tick a usage counter so the inliner can make good decisions.

In the megamorphic case, call to a stub that does a hash table lookup against a MegamorphicCache.

Megamorphic call sites face a loss of precision in usage counts. The call site count is not recorded and the usage counter of the target function is used as an approximation.

Monomorphic and megamorphic calls sites are reset to the polymorphic/unlinked state on hot reload.

Monomorphic and megamorphic calls sites do not check the stepping state, so they are reset to the polymorphic/unlinked state when stepping begins and disabled.

Back-edges now increment the usage counter in addition to checking it. This ensures function with loops containing monomorphic calls will eventually cross the optimization threshold.

Fixed backwards use of kMonomorphicEntryOffset and kPolymorphicEntryOffset.

Fixed C stack overflow when bouncing between the KBC interpreter and a simulator.

Bug: https://github.com/dart-lang/sdk/issues/26780
Bug: https://github.com/dart-lang/sdk/issues/36409
Bug: https://github.com/dart-lang/sdk/issues/36731
Change-Id: I78a49cccd962703a459288e71ce246ed845df474
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/102820
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
63 files changed
tree: 26805de8a52d8a63aaa5c2161640e5b6e8e6a910
  1. .github/
  2. build/
  3. client/
  4. docs/
  5. pkg/
  6. runtime/
  7. samples/
  8. samples-dev/
  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. .packages
  21. .vpython
  22. AUTHORS
  23. BUILD.gn
  24. CHANGELOG.md
  25. codereview.settings
  26. CONTRIBUTING.md
  27. DEPS
  28. LICENSE
  29. PATENTS
  30. PRESUBMIT.py
  31. README.dart-sdk
  32. README.md
  33. 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 has 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 PATENTS.

Using Dart

Visit the dart.dev to learn more about the language, tools, getting started, and more.

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

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.