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8321225: [JVMCI] HotSpotResolvedObjectTypeImpl.isLeafClass shouldn't create strong references #16943

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8321225: [JVMCI] HotSpotResolvedObjectTypeImpl.isLeafClass shouldn't create strong references #16943

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7 changes: 6 additions & 1 deletion src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotResolvedObjectTypeImpl.java
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Expand Up @@ -265,7 +265,12 @@ private AssumptionResult<ResolvedJavaType> concreteSubtype(HotSpotResolvedObject
* @return true if the type is a leaf class
*/
private boolean isLeafClass() {
return compilerToVM().getResolvedJavaType(this, config().subklassOffset, false) == null;
// In general, compilerToVM().getResolvedJavaType should always be used to read a Klass*
// from HotSpot data structures but that has the side effect of creating a strong reference
// to the Class which we do not want since it can cause class unloading problems. Since
// this code is only checking for null vs non-null so it should be safe to perform this
// check directly.
return UNSAFE.getLong(this.getKlassPointer() + config().subklassOffset) == 0;
}

/**
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