tree af89ba030fc7634c23ba6ac19cb376fd5b4f5d52
parent 000655e4d374bb1a7e7a335160cfa116e6968cff
author Stephen Adams <sra@google.com> 1681850379 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> 1681850379 +0000

[dart2js][js_runtime] Use Array.isArray more consistently

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>