--- /dev/null	2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/type/TypeReference.java	2016-12-09 00:47:17.575506749 -0800
@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2016, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.graalvm.compiler.core.common.type;
+
+import jdk.vm.ci.meta.Assumptions;
+import jdk.vm.ci.meta.ResolvedJavaType;
+
+/**
+ * This class represents a reference to a Java type and whether this reference is referring only to
+ * the represented type or also to its sub types in the class hierarchy. When creating a type
+ * reference, the following options have to be considered:
+ *
+ * <ul>
+ * <li>The reference should always only refer to the given concrete type. Use
+ * {@link #createExactTrusted(ResolvedJavaType)} for this purpose.</li>
+ * <li>The reference should be created without assumptions about the class hierarchy. The returned
+ * reference is exact only when the type is a leaf type (i.e., it cannot have subclasses). Depending
+ * on whether interface types can be trusted for this type reference use
+ * {@link #createWithoutAssumptions} or {@link #createTrustedWithoutAssumptions}.</li>
+ * <li>The reference should be created using assumptions about the class hierarchy. The returned
+ * reference is also exact, when there is only a single concrete sub type for the given type.
+ * Depending on whether interface types can be trusted for this type reference use {@link #create}
+ * or {@link #createTrusted}.</li>
+ * </ul>
+ *
+ * For the methods with untrusted interface types, a {@code null} reference will be constructed for
+ * untrusted interface types. Examples for interface types that cannot be trusted are types for
+ * parameters, fields, and return values. They are not checked by the Java verifier.
+ *
+ */
+public final class TypeReference {
+    private final ResolvedJavaType type;
+    private final boolean exactReference;
+
+    private TypeReference(ResolvedJavaType type, boolean exactReference) {
+        this.type = type;
+        this.exactReference = exactReference;
+    }
+
+    /**
+     * Creates an exact type reference using the given type.
+     */
+    public static TypeReference createExactTrusted(ResolvedJavaType type) {
+        if (type == null) {
+            return null;
+        }
+        return new TypeReference(type, true);
+    }
+
+    /**
+     * Creates a type reference using the given type without assumptions and without trusting
+     * interface types.
+     */
+    public static TypeReference createWithoutAssumptions(ResolvedJavaType type) {
+        return create(null, type);
+    }
+
+    /**
+     * Creates a type reference using the given type without assumptions and trusting interface
+     * types.
+     */
+    public static TypeReference createTrustedWithoutAssumptions(ResolvedJavaType type) {
+        return createTrusted(null, type);
+    }
+
+    /**
+     * Creates a type reference using the given type with assumptions and without trusting interface
+     * types.
+     */
+    public static TypeReference create(Assumptions assumptions, ResolvedJavaType type) {
+        return createTrusted(assumptions, filterInterfaceTypesOut(type));
+    }
+
+    /**
+     * Create a type reference using the given type with assumptions and trusting interface types.
+     */
+    public static TypeReference createTrusted(Assumptions assumptions, ResolvedJavaType type) {
+        if (type == null) {
+            return null;
+        }
+        ResolvedJavaType exactType = type.isLeaf() ? type : null;
+        if (exactType == null) {
+            Assumptions.AssumptionResult<ResolvedJavaType> leafConcreteSubtype = type.findLeafConcreteSubtype();
+            if (leafConcreteSubtype != null && leafConcreteSubtype.canRecordTo(assumptions)) {
+                leafConcreteSubtype.recordTo(assumptions);
+                exactType = leafConcreteSubtype.getResult();
+            }
+        }
+        if (exactType == null) {
+            return new TypeReference(type, false);
+        }
+        return new TypeReference(exactType, true);
+    }
+
+    /**
+     * The type this reference refers to.
+     */
+    public ResolvedJavaType getType() {
+        return type;
+    }
+
+    /**
+     * @return {@code true} if this reference is exact and only refers to the given type and
+     *         {@code false} if it also refers to its sub types.
+     */
+    public boolean isExact() {
+        return exactReference;
+    }
+
+    /**
+     * @return A new reference that is guaranteed to be exact.
+     */
+    public TypeReference asExactReference() {
+        if (isExact()) {
+            return this;
+        }
+        return new TypeReference(type, true);
+    }
+
+    private static ResolvedJavaType filterInterfaceTypesOut(ResolvedJavaType type) {
+        if (type != null) {
+            if (type.isArray()) {
+                ResolvedJavaType componentType = filterInterfaceTypesOut(type.getComponentType());
+                if (componentType != null) {
+                    return componentType.getArrayClass();
+                }
+                // Returns Object[].class
+                return type.getSuperclass().getArrayClass();
+            }
+            if (type.isInterface()) {
+                return null;
+            }
+        }
+        return type;
+    }
+
+    @Override
+    public String toString() {
+        return (isExact() ? "#" : "") + type;
+    }
+}