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[dart2js] Specialize strong 'is Object'
- o is Object --> o != null. - Avoid specializing 'is Object' to instanceof. Change-Id: Id882666d547ee2e06c6b92dec5a8070302dd9415 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/147686 Reviewed-by: Joshua Litt <joshualitt@google.com> Commit-Queue: Stephen Adams <sra@google.com>
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@ -12,7 +12,8 @@ import '../universe/class_hierarchy.dart' show ClassHierarchy;
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import '../world.dart' show JClosedWorld;
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enum IsTestSpecialization {
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null_,
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isNull,
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notNull,
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string,
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bool,
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num,
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@ -27,8 +28,7 @@ class SpecializedChecks {
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if (dartType is LegacyType) {
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DartType base = dartType.baseType;
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// `Never*` accepts only `null`.
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if (base is NeverType) return IsTestSpecialization.null_;
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// TODO(sra): Handle strong checking 'x is Object' --> `x != null`.
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if (base is NeverType) return IsTestSpecialization.isNull;
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// `Object*` is top and should be handled by constant folding.
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if (base.isObject) return null;
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return _findIsTestSpecialization(base, graph, closedWorld);
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@ -44,7 +44,7 @@ class SpecializedChecks {
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if (element == commonElements.nullClass ||
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element == commonElements.jsNullClass) {
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return IsTestSpecialization.null_;
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return IsTestSpecialization.isNull;
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}
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if (element == commonElements.jsStringClass ||
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@ -73,6 +73,9 @@ class SpecializedChecks {
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}
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DartTypes dartTypes = closedWorld.dartTypes;
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// Top types (here it could be Object in non-NNBD mode) should be constant
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// folded outside the specializer. This test protects logic below.
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if (dartTypes.isTopType(dartType)) return null;
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ElementEnvironment elementEnvironment = closedWorld.elementEnvironment;
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if (!dartTypes.isSubtype(
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elementEnvironment.getClassInstantiationToBounds(element),
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@ -84,6 +87,11 @@ class SpecializedChecks {
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return IsTestSpecialization.arrayTop;
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}
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if (dartType.isObject) {
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assert(!dartTypes.isTopType(dartType)); // Checked above.
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return IsTestSpecialization.notNull;
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}
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ClassHierarchy classHierarchy = closedWorld.classHierarchy;
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InterceptorData interceptorData = closedWorld.interceptorData;
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OutputUnitData outputUnitData = closedWorld.outputUnitData;
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@ -92,6 +100,7 @@ class SpecializedChecks {
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!interceptorData.isInterceptedClass(element) &&
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outputUnitData.hasOnlyNonDeferredImportPathsToClass(
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graph.element, element)) {
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assert(!dartType.isObject); // Checked above.
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return IsTestSpecialization.instanceof;
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}
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}
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@ -3492,9 +3492,10 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
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js.Expression test;
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switch (node.specialization) {
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case IsTestSpecialization.null_:
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// This case should be lowered to [HIdentity] during optimization.
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test = js.Binary(relation, value, js.LiteralNull());
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case IsTestSpecialization.isNull:
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case IsTestSpecialization.notNull:
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// These cases should be lowered using [HIdentity] during optimization.
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failedAt(node, 'Missing lowering');
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break;
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case IsTestSpecialization.string:
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@ -2176,12 +2176,17 @@ class SsaInstructionSimplifier extends HBaseVisitor
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SpecializedChecks.findIsTestSpecialization(
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dartType, _graph, _closedWorld);
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if (specialization == IsTestSpecialization.null_) {
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return HIdentity(
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if (specialization == IsTestSpecialization.isNull ||
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specialization == IsTestSpecialization.notNull) {
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HInstruction nullTest = HIdentity(
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node.checkedInput,
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_graph.addConstantNull(_closedWorld),
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null,
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_abstractValueDomain.boolType);
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if (specialization == IsTestSpecialization.isNull) return nullTest;
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nullTest.sourceInformation = node.sourceInformation;
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node.block.addBefore(node, nullTest);
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return HNot(nullTest, _abstractValueDomain.boolType);
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}
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if (specialization != null) {
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