| commit | 066962ff60ba7438d5863e9fc4de18a10674bc9e | [log] [tgz] |
|---|---|---|
| author | Stephen Adams <sra@google.com> | Wed Oct 16 23:10:11 2024 +0000 |
| committer | Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> | Wed Oct 16 23:10:11 2024 +0000 |
| tree | f29a20f732b6d1d70c6d08a47f107724a96a7d16 | |
| parent | cec29f1306da181c0d12db5c02f7eedcb91e18b8 [diff] |
[vm] Defer removal of bounds checks
Change how `@pragma('vm:unsafe:no-bounds-checks')` works.
Instead of never inserting the bounds check, the bounds check is added to the flow graph with a flag that it should later be removed, `omit_check`. The removal occurs in `RangeAnalysis::EliminateRedundantBoundsChecks`. This ensures that the indexed load is pinned by the check, preventing illegal code motion.
`@pragma('vm:unsafe:no-bounds-checks')` is not a mechanism to allow unsafe access. It means that the access is known to be safe because of invariants not apparent to the compiler. Keeping the bounds check in the flow graph allows range analysis to learn from the bounds constraints and perhaps remove other checks. A test was added for this scenario. I didn't see this in the wild, but I did see one case where a refined range allowed a boxing to be removed.
Bug: #56808
TEST=BoundsCheckElimination_Pragma_learning, BoundsCheckElimination_Pragma_learning_control
Change-Id: I5b3f4470d6c40c988a8a0ee563c765f4f5f9128b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389620
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
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 is free and open source.
See LICENSE and PATENT_GRANT.
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).
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.
The easiest way to contribute to Dart is to file issues.
You can also contribute patches, as described in Contributing.
Future plans for Dart are included in the combined Dart and Flutter roadmap on the Flutter wiki.