Stephen Adams
62a67ba5bc
The main reason is to do this change is to avoid inconsistencies in what is considered to be a `JSArray`. Using `Array.isArray` allows js-interop where the JavaScript code subclasses `Array`. dart2js-production results: ArrayLoop.pseudopoly.hoisted1-indexing -50.20% ArrayLoop.pseudopoly.indexing -35.18% Iteration.concat.manual 11.69% ListCopy.List.int.unmodifiable.2 12.03% ListCopy.for.int.2 12.58% ListCopy.spread.int.2 13.57% ListCopy.toList.fixed.100 16.06% ListCopy.List.of.fixed.100 16.96% ListCopy.toList.100 17.28% ListCopy.spread.int.cast.2 18.45% ObjectHash.hash.5 19.62% TypedDataPoly.A_UVx5.view.2 21.12% ObjectHash.manual.5 21.70% ListCopy.spread.int.map.2 21.96% ListCopy.spread.int.cast.100 22.12% TypedDataPoly.A_UVx5.view.100 23.04% ListCopy.spread.int.map.100 25.26% ListCopy.List.of.100 27.88% ImagingGaussianBlurOnce 29.67% MegaEquality 37.90% An investigation of the two regressions shows that they benefit from a micro-benchmarking effect. The previous code was monomorphic at the property access in `receiver.constructor == Array`. If this is forced to be polymorphic, the baseline is quite a bit worse, leading to an improvement in line with some of the other benchmarks. Change-Id: I5c265b1d7408fbd41da9c6fa17472bf648000c8d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/287140 Reviewed-by: Nate Biggs <natebiggs@google.com> Commit-Queue: Stephen Adams <sra@google.com>
Dart2JS is the Dart-to-JavaScript compiler for Dart. This compiler will provide high-quality translation from Dart to JavaScript. Some areas that will explored in this project are: * high-performance extensible scanner and parser * concrete type inferencing * fancy language tool support * programming environment integration * SSA-based intermediate representation * adaptive compilation on the client