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[dartdevc] Optimize cast operation

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Avoid checking for legacy, nullable, null and top. These checks should
all return false because if they were true the dispatch would have gone
directly to the as() or _check() methods on LegacyType, NullableType,
Null, DynamicType, and VoidType. Object? is dispatched through
NullableType.

Add is(), as(), and _check() instance methods to VoidType with logic
similar to DynamicType.

Change-Id: Ib28f40605c66fa7e8569ace405eba51035f2079a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138668
Reviewed-by: Mark Zhou <markzipan@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>
This commit is contained in:
Nicholas Shahan 2020-03-07 00:29:34 +00:00 committed by commit-bot@chromium.org
parent c1cf29b2d4
commit 4799f38767
2 changed files with 18 additions and 16 deletions
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19
sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart
View file

@ -420,24 +420,15 @@ bool instanceOf(obj, type) {
cast(obj, type, @notNull bool isImplicit) {
// We hoist the common case where null is checked against another type here
// for better performance.
if (obj == null) {
if (_isLegacy(type) ||
_isNullType(type) ||
_isTop(type) ||
_isNullable(type)) {
return obj;
}
if (_strictSubtypeChecks) {
return castError(obj, type, isImplicit);
}
if (obj == null && !_strictSubtypeChecks) {
// Check the null comparison cache to avoid emitting repeated warnings.
_nullWarnOnType(type);
return obj;
} else {
var actual = getReifiedType(obj);
if (isSubtypeOf(actual, type)) return obj;
}
var actual = getReifiedType(obj);
if (isSubtypeOf(actual, type)) {
return obj;
}
return castError(obj, type, isImplicit);
}

15
sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart
View file

@ -85,14 +85,15 @@ class DartType implements Type {
class DynamicType extends DartType {
toString() => 'dynamic';
@notNull
@JSExportName('is')
bool is_T(object) => true;
@JSExportName('as')
as_T(object) => object;
Object? as_T(Object? object) => object;
@JSExportName('_check')
check_T(object) => object;
Object? check_T(Object? object) => object;
}
@notNull
@ -412,6 +413,16 @@ final _dynamic = DynamicType();
class VoidType extends DartType {
toString() => 'void';
@notNull
@JSExportName('is')
bool is_T(object) => true;
@JSExportName('as')
Object? as_T(Object? object) => object;
@JSExportName('_check')
Object? check_T(Object? object) => object;
}
@JSExportName('void')