| commit | e962350dd658469eea8c3f4031d1f2d046bd6139 | [log] [tgz] |
|---|---|---|
| author | Stephen Adams <sra@google.com> | Thu Feb 06 16:54:50 2025 -0800 |
| committer | Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> | Thu Feb 06 16:54:50 2025 -0800 |
| tree | 7d9e47fc1ca91b9f781695008f9510f46029f24d | |
| parent | 7349ef5e1187c99a835f5f35466f1e5e37b0ca65 [diff] |
[dart2js] Simply is-test when type parameters not needed
Sometimes the type expression of a is-test can be widened to one that
does not use type variables:
```dart
void addAll(Iterable<E> items) {
if (items is List<E>) {
... items[i] ... // code specialized to lists
}
...
}
```
Changing `is List<E>` to `is List` is more efficient, but not possible
at the source level since the explicit type parameter is needed for
type promotion.
This change uses a predicate provided by the Kernel package to widen
an interface type when generating the CFG instructions for the
is-test. This can lead to knock-on optimizations like compiling `is X`
to `instanceof`.
Bug: #54998
Change-Id: I956b9d9b8a31ae40aee86e31def475baa9ab5cfe
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/408124
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
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