--- /dev/null	2017-01-22 10:16:57.869617664 -0800
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/GraphEncoder.java	2017-02-15 17:06:41.358751984 -0800
@@ -0,0 +1,548 @@
+/*
+ * Copyright (c) 2015, 2015, 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.nodes;
+
+import static org.graalvm.compiler.core.common.CompilationIdentifier.INVALID_COMPILATION_ID;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Objects;
+
+import org.graalvm.compiler.core.common.Fields;
+import org.graalvm.compiler.core.common.util.FrequencyEncoder;
+import org.graalvm.compiler.core.common.util.TypeConversion;
+import org.graalvm.compiler.core.common.util.TypeReader;
+import org.graalvm.compiler.core.common.util.TypeWriter;
+import org.graalvm.compiler.core.common.util.UnsafeArrayTypeWriter;
+import org.graalvm.compiler.debug.Debug;
+import org.graalvm.compiler.graph.Edges;
+import org.graalvm.compiler.graph.Node;
+import org.graalvm.compiler.graph.NodeClass;
+import org.graalvm.compiler.graph.NodeList;
+import org.graalvm.compiler.graph.NodeMap;
+import org.graalvm.compiler.graph.iterators.NodeIterable;
+import org.graalvm.compiler.nodes.StructuredGraph.AllowAssumptions;
+import org.graalvm.compiler.nodes.java.ExceptionObjectNode;
+
+import jdk.vm.ci.code.Architecture;
+
+/**
+ * Encodes a {@link StructuredGraph} to a compact byte[] array. All nodes of the graph and edges
+ * between the nodes are encoded. Primitive data fields of nodes are stored in the byte[] array.
+ * Object data fields of nodes are stored in a separate Object[] array.
+ *
+ * One encoder instance can be used to encode multiple graphs. This requires that {@link #prepare}
+ * is called for all graphs first, followed by one call to {@link #finishPrepare}. Then
+ * {@link #encode} can be called for all graphs. The {@link #getObjects() objects} and
+ * {@link #getNodeClasses() node classes} arrays do not change anymore after preparation.
+ *
+ * Multiple encoded graphs share the Object[] array, and elements of the Object[] array are
+ * de-duplicated using {@link Object#equals Object equality}. This uses the assumption and good
+ * coding practice that data objects are immutable if {@link Object#equals} is implemented.
+ * Unfortunately, this cannot be enforced.
+ *
+ * The Graal {@link NodeClass} does not have a unique id that allows class lookup from an id.
+ * Therefore, the encoded graph contains a {@link NodeClass}[] array for lookup, and type ids are
+ * encoding-local.
+ *
+ * The encoded graph has the following structure: First, all nodes and their edges are serialized.
+ * The start offset of every node is then known. The raw node data is followed by a "table of
+ * contents" that lists the start offset for every node.
+ *
+ * The beginning of that table of contents is the return value of {@link #encode} and stored in
+ * {@link EncodedGraph#getStartOffset()}. The order of nodes in the table of contents is the
+ * {@link NodeOrder#orderIds orderId} of a node. Note that the orderId is not the regular node id
+ * that every Graal graph node gets assigned. The orderId is computed and used just for encoding and
+ * decoding. The orderId of fixed nodes is assigned in reverse postorder. The decoder processes
+ * nodes using that order, which ensures that all predecessors of a node (including all
+ * {@link EndNode predecessors} of a {@link AbstractBeginNode block}) are decoded before the node.
+ * The order id of floating node does not matter during decoding, so floating nodes get order ids
+ * after all fixed nodes. The order id is used to encode edges between nodes
+ *
+ * Structure of an encoded node:
+ *
+ * <pre>
+ * struct Node {
+ *   unsigned typeId
+ *   signed[] properties
+ *   unsigned[] successorOrderIds
+ *   unsigned[] inputOrderIds
+ * }
+ * </pre>
+ *
+ * All numbers (unsigned and signed) are stored using a variable-length encoding as defined in
+ * {@link TypeReader} and {@link TypeWriter}. Especially orderIds are small, so the variable-length
+ * encoding is important to keep the encoding compact.
+ *
+ * The properties, successors, and inputs are written in the order as defined in
+ * {@link NodeClass#getData}, {@link NodeClass#getSuccessorEdges()}, and
+ * {@link NodeClass#getInputEdges()}. For variable-length successors and input lists, first the
+ * length is written and then the orderIds. There is a distinction between null lists (encoded as
+ * length -1) and empty lists (encoded as length 0). No reverse edges are written (predecessors,
+ * usages) since that information can be easily restored during decoding.
+ *
+ * Some nodes have additional information written after the properties, successors, and inputs:
+ * <li><item>{@link AbstractEndNode}: the orderId of the merge node and then all {@link PhiNode phi
+ * mappings} from this end to the merge node are written. <item>{@link LoopExitNode}: the orderId of
+ * all {@link ProxyNode proxy nodes} of the loop exit is written.</li>
+ */
+public class GraphEncoder {
+
+    /** The orderId that always represents {@code null}. */
+    public static final int NULL_ORDER_ID = 0;
+    /** The orderId of the {@link StructuredGraph#start() start node} of the encoded graph. */
+    public static final int START_NODE_ORDER_ID = 1;
+    /**
+     * The orderId of the first actual node after the {@link StructuredGraph#start() start node}.
+     */
+    public static final int FIRST_NODE_ORDER_ID = 2;
+
+    /**
+     * The known offset between the orderId of a {@link AbstractBeginNode} and its
+     * {@link AbstractBeginNode#next() successor}.
+     */
+    protected static final int BEGIN_NEXT_ORDER_ID_OFFSET = 1;
+
+    protected final Architecture architecture;
+
+    /**
+     * Collects all non-primitive data referenced from nodes. The encoding uses an index into an
+     * array for decoding. Because of the variable-length encoding, it is beneficial that frequently
+     * used objects have the small indices.
+     */
+    protected final FrequencyEncoder<Object> objects;
+    /**
+     * Collects all node classes referenced in graphs. This is necessary because {@link NodeClass}
+     * currently does not have a unique id.
+     */
+    protected final FrequencyEncoder<NodeClass<?>> nodeClasses;
+    /** The writer for the encoded graphs. */
+    protected final UnsafeArrayTypeWriter writer;
+
+    /** The last snapshot of {@link #objects} that was retrieved. */
+    protected Object[] objectsArray;
+    /** The last snapshot of {@link #nodeClasses} that was retrieved. */
+    protected NodeClass<?>[] nodeClassesArray;
+
+    /**
+     * Utility method that does everything necessary to encode a single graph.
+     */
+    public static EncodedGraph encodeSingleGraph(StructuredGraph graph, Architecture architecture) {
+        GraphEncoder encoder = new GraphEncoder(architecture);
+        encoder.prepare(graph);
+        encoder.finishPrepare();
+        long startOffset = encoder.encode(graph);
+        return new EncodedGraph(encoder.getEncoding(), startOffset, encoder.getObjects(), encoder.getNodeClasses(), graph.getAssumptions(), graph.getMethods());
+    }
+
+    public GraphEncoder(Architecture architecture) {
+        this.architecture = architecture;
+        objects = FrequencyEncoder.createEqualityEncoder();
+        nodeClasses = FrequencyEncoder.createIdentityEncoder();
+        writer = UnsafeArrayTypeWriter.create(architecture.supportsUnalignedMemoryAccess());
+    }
+
+    /**
+     * Must be invoked before {@link #finishPrepare()} and {@link #encode}.
+     */
+    public void prepare(StructuredGraph graph) {
+        for (Node node : graph.getNodes()) {
+            nodeClasses.addObject(node.getNodeClass());
+
+            NodeClass<?> nodeClass = node.getNodeClass();
+            objects.addObject(node.getNodeSourcePosition());
+            for (int i = 0; i < nodeClass.getData().getCount(); i++) {
+                if (!nodeClass.getData().getType(i).isPrimitive()) {
+                    objects.addObject(nodeClass.getData().get(node, i));
+                }
+            }
+            if (node instanceof Invoke) {
+                objects.addObject(((Invoke) node).getContextType());
+            }
+        }
+    }
+
+    public void finishPrepare() {
+        objectsArray = objects.encodeAll(new Object[objects.getLength()]);
+        nodeClassesArray = nodeClasses.encodeAll(new NodeClass<?>[nodeClasses.getLength()]);
+    }
+
+    public Object[] getObjects() {
+        return objectsArray;
+    }
+
+    public NodeClass<?>[] getNodeClasses() {
+        return nodeClassesArray;
+    }
+
+    /**
+     * Compresses a graph to a byte array. Multiple graphs can be compressed with the same
+     * {@link GraphEncoder}.
+     *
+     * @param graph The graph to encode
+     */
+    public long encode(StructuredGraph graph) {
+        assert objectsArray != null && nodeClassesArray != null : "finishPrepare() must be called before encode()";
+
+        NodeOrder nodeOrder = new NodeOrder(graph);
+        int nodeCount = nodeOrder.nextOrderId;
+        assert nodeOrder.orderIds.get(graph.start()) == START_NODE_ORDER_ID;
+        assert nodeOrder.orderIds.get(graph.start().next()) == FIRST_NODE_ORDER_ID;
+        assert nodeCount == graph.getNodeCount() + 1;
+
+        long[] nodeStartOffsets = new long[nodeCount];
+        for (Map.Entry<Node, Integer> entry : nodeOrder.orderIds.entries()) {
+            Node node = entry.getKey();
+            Integer orderId = entry.getValue();
+
+            assert !(node instanceof AbstractBeginNode) || nodeOrder.orderIds.get(((AbstractBeginNode) node).next()) == orderId + BEGIN_NEXT_ORDER_ID_OFFSET;
+            nodeStartOffsets[orderId] = writer.getBytesWritten();
+
+            /* Write out the type, properties, and edges. */
+            NodeClass<?> nodeClass = node.getNodeClass();
+            writer.putUV(nodeClasses.getIndex(nodeClass));
+            writeProperties(node, nodeClass.getData());
+            writeEdges(node, nodeClass.getEdges(Edges.Type.Successors), nodeOrder);
+            writeEdges(node, nodeClass.getEdges(Edges.Type.Inputs), nodeOrder);
+
+            /* Special handling for some nodes that require additional information for decoding. */
+            if (node instanceof AbstractEndNode) {
+                AbstractEndNode end = (AbstractEndNode) node;
+                AbstractMergeNode merge = end.merge();
+                /*
+                 * Write the orderId of the merge. The merge is not a successor in the Graal graph
+                 * (only the merge has an input edge to the EndNode).
+                 */
+                writeOrderId(merge, nodeOrder);
+
+                /*
+                 * Write all phi mappings (the oderId of the phi input for this EndNode, and the
+                 * orderId of the phi node.
+                 */
+                writer.putUV(merge.phis().count());
+                for (PhiNode phi : merge.phis()) {
+                    writeOrderId(phi.valueAt(end), nodeOrder);
+                    writeOrderId(phi, nodeOrder);
+                }
+
+            } else if (node instanceof LoopExitNode) {
+                LoopExitNode exit = (LoopExitNode) node;
+                writeOrderId(exit.stateAfter(), nodeOrder);
+                /* Write all proxy nodes of the LoopExitNode. */
+                writer.putUV(exit.proxies().count());
+                for (ProxyNode proxy : exit.proxies()) {
+                    writeOrderId(proxy, nodeOrder);
+                }
+
+            } else if (node instanceof Invoke) {
+                Invoke invoke = (Invoke) node;
+                assert invoke.stateDuring() == null : "stateDuring is not used in high-level graphs";
+
+                writeObjectId(invoke.getContextType());
+                writeOrderId(invoke.callTarget(), nodeOrder);
+                writeOrderId(invoke.stateAfter(), nodeOrder);
+                writeOrderId(invoke.next(), nodeOrder);
+                if (invoke instanceof InvokeWithExceptionNode) {
+                    InvokeWithExceptionNode invokeWithExcpetion = (InvokeWithExceptionNode) invoke;
+                    ExceptionObjectNode exceptionEdge = (ExceptionObjectNode) invokeWithExcpetion.exceptionEdge();
+
+                    writeOrderId(invokeWithExcpetion.next().next(), nodeOrder);
+                    writeOrderId(invokeWithExcpetion.exceptionEdge(), nodeOrder);
+                    writeOrderId(exceptionEdge.stateAfter(), nodeOrder);
+                    writeOrderId(exceptionEdge.next(), nodeOrder);
+                }
+            }
+        }
+
+        /* Write out the table of contents with the start offset for all nodes. */
+        long nodeTableStart = writer.getBytesWritten();
+        writer.putUV(nodeCount);
+        for (int i = 0; i < nodeCount; i++) {
+            assert i == NULL_ORDER_ID || i == START_NODE_ORDER_ID || nodeStartOffsets[i] > 0;
+            writer.putUV(nodeTableStart - nodeStartOffsets[i]);
+        }
+
+        /* Check that the decoding of the encode graph is the same as the input. */
+        assert verifyEncoding(graph, new EncodedGraph(getEncoding(), nodeTableStart, getObjects(), getNodeClasses(), graph.getAssumptions(), graph.getMethods()), architecture);
+
+        return nodeTableStart;
+    }
+
+    public byte[] getEncoding() {
+        return writer.toArray(new byte[TypeConversion.asS4(writer.getBytesWritten())]);
+    }
+
+    static class NodeOrder {
+        protected final NodeMap<Integer> orderIds;
+        protected int nextOrderId;
+
+        NodeOrder(StructuredGraph graph) {
+            this.orderIds = new NodeMap<>(graph);
+            this.nextOrderId = START_NODE_ORDER_ID;
+
+            /* Order the fixed nodes of the graph in reverse postorder. */
+            Deque<AbstractBeginNode> nodeQueue = new ArrayDeque<>();
+            FixedNode current = graph.start();
+            do {
+                add(current);
+                if (current instanceof AbstractBeginNode) {
+                    add(((AbstractBeginNode) current).next());
+                }
+
+                if (current instanceof FixedWithNextNode) {
+                    current = ((FixedWithNextNode) current).next;
+                } else {
+                    if (current instanceof ControlSplitNode) {
+                        for (Node successor : current.successors()) {
+                            if (successor != null) {
+                                nodeQueue.addFirst((AbstractBeginNode) successor);
+                            }
+                        }
+                    } else if (current instanceof EndNode) {
+                        AbstractMergeNode merge = ((AbstractEndNode) current).merge();
+                        boolean allForwardEndsVisited = true;
+                        for (int i = 0; i < merge.forwardEndCount(); i++) {
+                            if (orderIds.get(merge.forwardEndAt(i)) == null) {
+                                allForwardEndsVisited = false;
+                                break;
+                            }
+                        }
+                        if (allForwardEndsVisited) {
+                            nodeQueue.add(merge);
+                        }
+                    }
+                    current = nodeQueue.pollFirst();
+                }
+            } while (current != null);
+
+            for (Node node : graph.getNodes()) {
+                assert (node instanceof FixedNode) == (orderIds.get(node) != null) : "all fixed nodes must be ordered";
+                add(node);
+            }
+        }
+
+        private void add(Node node) {
+            if (orderIds.get(node) == null) {
+                orderIds.set(node, nextOrderId);
+                nextOrderId++;
+            }
+        }
+    }
+
+    protected void writeProperties(Node node, Fields fields) {
+        writeObjectId(node.getNodeSourcePosition());
+        for (int idx = 0; idx < fields.getCount(); idx++) {
+            if (fields.getType(idx).isPrimitive()) {
+                long primitive = fields.getRawPrimitive(node, idx);
+                writer.putSV(primitive);
+            } else {
+                Object property = fields.get(node, idx);
+                writeObjectId(property);
+            }
+        }
+    }
+
+    protected void writeEdges(Node node, Edges edges, NodeOrder nodeOrder) {
+        for (int idx = 0; idx < edges.getDirectCount(); idx++) {
+            if (GraphDecoder.skipEdge(node, edges, idx, true, false)) {
+                /* Edge is not needed for decoding, so we must not write it. */
+                continue;
+            }
+            Node edge = Edges.getNode(node, edges.getOffsets(), idx);
+            writeOrderId(edge, nodeOrder);
+        }
+        for (int idx = edges.getDirectCount(); idx < edges.getCount(); idx++) {
+            if (GraphDecoder.skipEdge(node, edges, idx, false, false)) {
+                /* Edge is not needed for decoding, so we must not write it. */
+                continue;
+            }
+            NodeList<Node> edgeList = Edges.getNodeList(node, edges.getOffsets(), idx);
+            if (edgeList == null) {
+                writer.putSV(-1);
+            } else {
+                writer.putSV(edgeList.size());
+                for (Node edge : edgeList) {
+                    writeOrderId(edge, nodeOrder);
+                }
+            }
+        }
+    }
+
+    protected void writeOrderId(Node node, NodeOrder nodeOrder) {
+        writer.putUV(node == null ? NULL_ORDER_ID : nodeOrder.orderIds.get(node));
+    }
+
+    protected void writeObjectId(Object object) {
+        writer.putUV(objects.getIndex(object));
+    }
+
+    /**
+     * Verification code that checks that the decoding of an encode graph is the same as the
+     * original graph.
+     */
+    @SuppressWarnings("try")
+    public static boolean verifyEncoding(StructuredGraph originalGraph, EncodedGraph encodedGraph, Architecture architecture) {
+        StructuredGraph decodedGraph = new StructuredGraph(originalGraph.method(), AllowAssumptions.YES, INVALID_COMPILATION_ID);
+        GraphDecoder decoder = new GraphDecoder(architecture);
+        decoder.decode(decodedGraph, encodedGraph);
+
+        decodedGraph.verify();
+        try {
+            GraphComparison.verifyGraphsEqual(originalGraph, decodedGraph);
+        } catch (Throwable ex) {
+            try (Debug.Scope scope = Debug.scope("GraphEncoder")) {
+                Debug.dump(Debug.INFO_LOG_LEVEL, originalGraph, "Original Graph");
+                Debug.dump(Debug.INFO_LOG_LEVEL, decodedGraph, "Decoded Graph");
+            }
+            throw ex;
+        }
+        return true;
+    }
+}
+
+class GraphComparison {
+    public static boolean verifyGraphsEqual(StructuredGraph expectedGraph, StructuredGraph actualGraph) {
+        NodeMap<Node> nodeMapping = new NodeMap<>(expectedGraph);
+        Deque<Pair<Node, Node>> workList = new ArrayDeque<>();
+
+        pushToWorklist(expectedGraph.start(), actualGraph.start(), nodeMapping, workList);
+        while (!workList.isEmpty()) {
+            Pair<Node, Node> pair = workList.removeFirst();
+            Node expectedNode = pair.first;
+            Node actualNode = pair.second;
+            assert expectedNode.getClass() == actualNode.getClass();
+
+            NodeClass<?> nodeClass = expectedNode.getNodeClass();
+            assert nodeClass == actualNode.getNodeClass();
+
+            if (expectedNode instanceof MergeNode) {
+                /* The order of the ends can be different, so ignore them. */
+                verifyNodesEqual(expectedNode.inputs(), actualNode.inputs(), nodeMapping, workList, true);
+            } else if (expectedNode instanceof PhiNode) {
+                verifyPhi((PhiNode) expectedNode, (PhiNode) actualNode, nodeMapping, workList);
+            } else {
+                verifyNodesEqual(expectedNode.inputs(), actualNode.inputs(), nodeMapping, workList, false);
+            }
+            verifyNodesEqual(expectedNode.successors(), actualNode.successors(), nodeMapping, workList, false);
+
+            if (expectedNode instanceof LoopEndNode) {
+                LoopEndNode actualLoopEnd = (LoopEndNode) actualNode;
+                assert actualLoopEnd.loopBegin().loopEnds().snapshot().indexOf(actualLoopEnd) == actualLoopEnd.endIndex();
+            } else {
+                for (int i = 0; i < nodeClass.getData().getCount(); i++) {
+                    Object expectedProperty = nodeClass.getData().get(expectedNode, i);
+                    Object actualProperty = nodeClass.getData().get(actualNode, i);
+                    assert Objects.equals(expectedProperty, actualProperty);
+                }
+            }
+
+            if (expectedNode instanceof EndNode) {
+                /* Visit the merge node, which is the one and only usage of the EndNode. */
+                assert expectedNode.usages().count() == 1;
+                assert actualNode.usages().count() == 1;
+                verifyNodesEqual(expectedNode.usages(), actualNode.usages(), nodeMapping, workList, false);
+            }
+
+            if (expectedNode instanceof AbstractEndNode) {
+                /* Visit the input values of the merge phi functions for this EndNode. */
+                verifyPhis((AbstractEndNode) expectedNode, (AbstractEndNode) actualNode, nodeMapping, workList);
+            }
+        }
+
+        return true;
+    }
+
+    protected static void verifyPhi(PhiNode expectedPhi, PhiNode actualPhi, NodeMap<Node> nodeMapping, Deque<Pair<Node, Node>> workList) {
+        AbstractMergeNode expectedMergeNode = expectedPhi.merge();
+        AbstractMergeNode actualMergeNode = actualPhi.merge();
+        assert actualMergeNode == nodeMapping.get(expectedMergeNode);
+
+        for (EndNode expectedEndNode : expectedMergeNode.ends) {
+            EndNode actualEndNode = (EndNode) nodeMapping.get(expectedEndNode);
+            if (actualEndNode != null) {
+                ValueNode expectedPhiInput = expectedPhi.valueAt(expectedEndNode);
+                ValueNode actualPhiInput = actualPhi.valueAt(actualEndNode);
+                verifyNodeEqual(expectedPhiInput, actualPhiInput, nodeMapping, workList, false);
+            }
+        }
+    }
+
+    protected static void verifyPhis(AbstractEndNode expectedEndNode, AbstractEndNode actualEndNode, NodeMap<Node> nodeMapping, Deque<Pair<Node, Node>> workList) {
+        AbstractMergeNode expectedMergeNode = expectedEndNode.merge();
+        AbstractMergeNode actualMergeNode = (AbstractMergeNode) nodeMapping.get(expectedMergeNode);
+        assert actualMergeNode != null;
+
+        for (PhiNode expectedPhi : expectedMergeNode.phis()) {
+            PhiNode actualPhi = (PhiNode) nodeMapping.get(expectedPhi);
+            if (actualPhi != null) {
+                ValueNode expectedPhiInput = expectedPhi.valueAt(expectedEndNode);
+                ValueNode actualPhiInput = actualPhi.valueAt(actualEndNode);
+                verifyNodeEqual(expectedPhiInput, actualPhiInput, nodeMapping, workList, false);
+            }
+        }
+    }
+
+    private static void verifyNodesEqual(NodeIterable<Node> expectedNodes, NodeIterable<Node> actualNodes, NodeMap<Node> nodeMapping, Deque<Pair<Node, Node>> workList, boolean ignoreEndNode) {
+        Iterator<Node> actualIter = actualNodes.iterator();
+        for (Node expectedNode : expectedNodes) {
+            verifyNodeEqual(expectedNode, actualIter.next(), nodeMapping, workList, ignoreEndNode);
+        }
+        assert !actualIter.hasNext();
+    }
+
+    protected static void verifyNodeEqual(Node expectedNode, Node actualNode, NodeMap<Node> nodeMapping, Deque<Pair<Node, Node>> workList, boolean ignoreEndNode) {
+        assert expectedNode.getClass() == actualNode.getClass();
+        if (ignoreEndNode && expectedNode instanceof EndNode) {
+            return;
+        }
+
+        Node existing = nodeMapping.get(expectedNode);
+        if (existing != null) {
+            assert existing == actualNode;
+        } else {
+            pushToWorklist(expectedNode, actualNode, nodeMapping, workList);
+        }
+    }
+
+    protected static void pushToWorklist(Node expectedNode, Node actualNode, NodeMap<Node> nodeMapping, Deque<Pair<Node, Node>> workList) {
+        nodeMapping.set(expectedNode, actualNode);
+        if (expectedNode instanceof AbstractEndNode) {
+            /* To ensure phi nodes have been added, we handle everything before block ends. */
+            workList.addLast(new Pair<>(expectedNode, actualNode));
+        } else {
+            workList.addFirst(new Pair<>(expectedNode, actualNode));
+        }
+    }
+}
+
+class Pair<F, S> {
+    public final F first;
+    public final S second;
+
+    Pair(F first, S second) {
+        this.first = first;
+        this.second = second;
+    }
+}