src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotResolvedObjectTypeImpl.java

@@ -165,13 +165,29 @@
         return javaComponentType == null ? null : runtime().fromClass(javaComponentType);
     }
 
     @Override
     public AssumptionResult<ResolvedJavaType> findLeafConcreteSubtype() {
+        if (isLeaf()) {
+            // No assumptions are required.
+            return new AssumptionResult<>(this);
+        }
         HotSpotVMConfig config = config();
         if (isArray()) {
-            return getElementalType().isLeaf() ? new AssumptionResult<>(this) : null;
+            ResolvedJavaType elementalType = getElementalType();
+            AssumptionResult<ResolvedJavaType> elementType = elementalType.findLeafConcreteSubtype();
+            if (elementType != null && elementType.getResult().equals(elementalType)) {
+                /*
+                 * If the elementType is leaf then the array is leaf under the same assumptions but
+                 * only if the element type is exactly the leaf type. The element type can be
+                 * abstract even if there is only one implementor of the abstract type.
+                 */
+                AssumptionResult<ResolvedJavaType> result = new AssumptionResult<>(this);
+                result.add(elementType);
+                return result;
+            }
+            return null;
         } else if (isInterface()) {
             HotSpotResolvedObjectTypeImpl implementor = getSingleImplementor();
             /*
              * If the implementor field contains itself that indicates that the interface has more
              * than one implementors (see: InstanceKlass::add_implementor).

@@ -190,12 +206,11 @@
                     newResult.add(leafConcreteSubtype);
                     return newResult;
                 }
                 return null;
             }
-
-            return new AssumptionResult<>(implementor, new LeafType(implementor), new ConcreteSubtype(this, implementor));
+            return concreteSubtype(implementor);
         } else {
             HotSpotResolvedObjectTypeImpl type = this;
             while (type.isAbstract()) {
                 HotSpotResolvedObjectTypeImpl subklass = type.getSubklass();
                 if (subklass == null || UNSAFE.getAddress(subklass.getMetaspaceKlass() + config.nextSiblingOffset) != 0) {

@@ -205,18 +220,26 @@
             }
             if (type.isAbstract() || type.isInterface() || !type.isLeafClass()) {
                 return null;
             }
             if (this.isAbstract()) {
-                return new AssumptionResult<>(type, new LeafType(type), new ConcreteSubtype(this, type));
+                return concreteSubtype(type);
             } else {
                 assert this.equals(type);
                 return new AssumptionResult<>(type, new LeafType(type));
             }
         }
     }
 
+    private AssumptionResult<ResolvedJavaType> concreteSubtype(HotSpotResolvedObjectTypeImpl type) {
+        if (type.isLeaf()) {
+            return new AssumptionResult<>(type, new ConcreteSubtype(this, type));
+        } else {
+            return new AssumptionResult<>(type, new LeafType(type), new ConcreteSubtype(this, type));
+        }
+    }
+
     /**
      * Returns if type {@code type} is a leaf class. This is the case if the
      * {@code Klass::_subklass} field of the underlying class is zero.
      *
      * @return true if the type is a leaf class