commit c121db286a03ee5f8558e94acf57c76687e57d8e
author Vyacheslav Egorov <vegorov@google.com> Wed Sep 06 14:09:11 2023 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Sep 06 14:09:11 2023 +0000
tree 71ee59c93356f61433ed0e95c2fae191f13679a6
parent 952b7232c3c82a73e7549bc35c1194e0c55c8f7a

[lib] Improve IndexedIterable performance on VM

* Check against raw `EfficientLengthIterable` instead of specifying
  its type parameter. Both checks are equivalent in this context as
  `EfficientLengthIterable` is an internal marker interface and an
  instance of `Iterable<T>` can never be an instance of
  `EfficientLengthIterable` but not an instance of
  `EfficientLengthIterable<T>`.
  VM compiler is currently not good enough to eliminate the
  `is` check if involves an uninstantiated type
  (see https://dartbug.com/53445).
* Force inlining of `IndexedIterable` factory,
  `IndexedIterable.get iterator` and `IterableExtensions.indexed`.

These changes significantly reduce overhead of for-in-indexed
when compared to baseline classical loop: before these changes
for-in-indexed is 13x slower than classical loop, after these
changes it is only 2.8x slower.

Performance comparison was using the following benchmark kernels:

```dart
final list = List<int>.generate(10000, (i) => i);

// For for-in-indexed
var result = 0;
for (var (i, e) in list.indexed) {
  result ^= (i & e);
}

// For classical loop
var result = 0;
for (var i = 0; i < list.length; i++) {
  result ^= (i & list[i]);
}
```

CoreLibraryReviewExempt: No API changes, VM specific optimisations.
Change-Id: Ic935a2aab2eda0837981184d872ee1eeef89ee7a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/324461
Reviewed-by: Lasse Nielsen <lrn@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>