/*
 * Copyright (c) 2011, 2018, 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.virtual.phases.ea;

import java.util.ArrayList;
import java.util.BitSet;
import java.util.Iterator;
import java.util.List;
import java.util.function.IntUnaryOperator;

import jdk.internal.vm.compiler.collections.EconomicMap;
import jdk.internal.vm.compiler.collections.EconomicSet;
import jdk.internal.vm.compiler.collections.Equivalence;
import org.graalvm.compiler.core.common.GraalOptions;
import org.graalvm.compiler.core.common.cfg.Loop;
import org.graalvm.compiler.core.common.spi.ConstantFieldProvider;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.debug.CounterKey;
import org.graalvm.compiler.debug.DebugContext;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeBitMap;
import org.graalvm.compiler.graph.Position;
import org.graalvm.compiler.graph.spi.Canonicalizable;
import org.graalvm.compiler.nodes.AbstractEndNode;
import org.graalvm.compiler.nodes.CallTargetNode;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.ControlSinkNode;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.FixedWithNextNode;
import org.graalvm.compiler.nodes.FrameState;
import org.graalvm.compiler.nodes.Invoke;
import org.graalvm.compiler.nodes.LoopBeginNode;
import org.graalvm.compiler.nodes.LoopExitNode;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.PhiNode;
import org.graalvm.compiler.nodes.ProxyNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.ValuePhiNode;
import org.graalvm.compiler.nodes.ValueProxyNode;
import org.graalvm.compiler.nodes.VirtualState;
import org.graalvm.compiler.nodes.VirtualState.NodeClosure;
import org.graalvm.compiler.nodes.cfg.Block;
import org.graalvm.compiler.nodes.spi.LoweringProvider;
import org.graalvm.compiler.nodes.spi.NodeWithState;
import org.graalvm.compiler.nodes.spi.Virtualizable;
import org.graalvm.compiler.nodes.spi.VirtualizableAllocation;
import org.graalvm.compiler.nodes.spi.VirtualizerTool;
import org.graalvm.compiler.nodes.virtual.AllocatedObjectNode;
import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;
import org.graalvm.compiler.virtual.nodes.VirtualObjectState;

import jdk.vm.ci.meta.ConstantReflectionProvider;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.MetaAccessProvider;

public abstract class PartialEscapeClosure<BlockT extends PartialEscapeBlockState<BlockT>> extends EffectsClosure<BlockT> {

    public static final CounterKey COUNTER_MATERIALIZATIONS = DebugContext.counter("Materializations");
    public static final CounterKey COUNTER_MATERIALIZATIONS_PHI = DebugContext.counter("MaterializationsPhi");
    public static final CounterKey COUNTER_MATERIALIZATIONS_MERGE = DebugContext.counter("MaterializationsMerge");
    public static final CounterKey COUNTER_MATERIALIZATIONS_UNHANDLED = DebugContext.counter("MaterializationsUnhandled");
    public static final CounterKey COUNTER_MATERIALIZATIONS_LOOP_REITERATION = DebugContext.counter("MaterializationsLoopReiteration");
    public static final CounterKey COUNTER_MATERIALIZATIONS_LOOP_END = DebugContext.counter("MaterializationsLoopEnd");
    public static final CounterKey COUNTER_ALLOCATION_REMOVED = DebugContext.counter("AllocationsRemoved");
    public static final CounterKey COUNTER_MEMORYCHECKPOINT = DebugContext.counter("MemoryCheckpoint");

    
Nodes with inputs that were modified during analysis are marked in this bitset - this way
nodes that are not influenced at all by analysis can be rejected quickly.
/**
     * Nodes with inputs that were modified during analysis are marked in this bitset - this way
     * nodes that are not influenced at all by analysis can be rejected quickly.
     */
    private final NodeBitMap hasVirtualInputs;

    
This is handed out to implementers of Virtualizable. /**
     * This is handed out to implementers of {@link Virtualizable}.
     */
    protected final VirtualizerToolImpl tool;

    
The indexes into this array correspond to VirtualObjectNode.getObjectId(). /**
     * The indexes into this array correspond to {@link VirtualObjectNode#getObjectId()}.
     */
    public final ArrayList<VirtualObjectNode> virtualObjects = new ArrayList<>();
    public final DebugContext debug;

    @Override
    public boolean needsApplyEffects() {
        if (hasChanged()) {
            return true;
        }
        /*
         * If there is a mismatch between the number of materializations and the number of
         * virtualizations, we need to apply effects, even if there were no other significant
         * changes to the graph. This applies to each block, since moving from one block to the
         * other can also be important (if the probabilities of the block differ).
         */
        for (Block block : cfg.getBlocks()) {
            GraphEffectList effects = blockEffects.get(block);
            if (effects != null) {
                if (effects.getVirtualizationDelta() != 0) {
                    return true;
                }
            }
        }
        return false;
    }

    private final class CollectVirtualObjectsClosure extends NodeClosure<ValueNode> {
        private final EconomicSet<VirtualObjectNode> virtual;
        private final GraphEffectList effects;
        private final BlockT state;

        private CollectVirtualObjectsClosure(EconomicSet<VirtualObjectNode> virtual, GraphEffectList effects, BlockT state) {
            this.virtual = virtual;
            this.effects = effects;
            this.state = state;
        }

        @Override
        public void apply(Node usage, ValueNode value) {
            if (value instanceof VirtualObjectNode) {
                VirtualObjectNode object = (VirtualObjectNode) value;
                if (object.getObjectId() != -1 && state.getObjectStateOptional(object) != null) {
                    virtual.add(object);
                }
            } else {
                ValueNode alias = getAlias(value);
                if (alias instanceof VirtualObjectNode) {
                    VirtualObjectNode object = (VirtualObjectNode) alias;
                    virtual.add(object);
                    effects.replaceFirstInput(usage, value, object);
                }
            }
        }
    }

    
Final subclass of PartialEscapeClosure, for performance and to make everything behave nicely
with generics.
/**
     * Final subclass of PartialEscapeClosure, for performance and to make everything behave nicely
     * with generics.
     */
    public static final class Final extends PartialEscapeClosure<PartialEscapeBlockState.Final> {

        public Final(ScheduleResult schedule, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, ConstantFieldProvider constantFieldProvider,
                        LoweringProvider loweringProvider) {
            super(schedule, metaAccess, constantReflection, constantFieldProvider, loweringProvider);
        }

        @Override
        protected PartialEscapeBlockState.Final getInitialState() {
            return new PartialEscapeBlockState.Final(tool.getOptions(), tool.getDebug());
        }

        @Override
        protected PartialEscapeBlockState.Final cloneState(PartialEscapeBlockState.Final oldState) {
            return new PartialEscapeBlockState.Final(oldState);
        }
    }

    public PartialEscapeClosure(ScheduleResult schedule, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, ConstantFieldProvider constantFieldProvider) {
        this(schedule, metaAccess, constantReflection, constantFieldProvider, null);
    }

    public PartialEscapeClosure(ScheduleResult schedule, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, ConstantFieldProvider constantFieldProvider,
                    LoweringProvider loweringProvider) {
        super(schedule, schedule.getCFG());
        StructuredGraph graph = schedule.getCFG().graph;
        this.hasVirtualInputs = graph.createNodeBitMap();
        this.debug = graph.getDebug();
        this.tool = new VirtualizerToolImpl(metaAccess, constantReflection, constantFieldProvider, this, graph.getAssumptions(), graph.getOptions(), debug, loweringProvider);
    }

    
Returns:
true if the node was deleted, false otherwise/**
     * @return true if the node was deleted, false otherwise
     */
    @Override
    protected boolean processNode(Node node, BlockT state, GraphEffectList effects, FixedWithNextNode lastFixedNode) {
        /*
         * These checks make up for the fact that an earliest schedule moves CallTargetNodes upwards
         * and thus materializes virtual objects needlessly. Also, FrameStates and ConstantNodes are
         * scheduled, but can safely be ignored.
         */
        if (node instanceof CallTargetNode || node instanceof FrameState || node instanceof ConstantNode) {
            return false;
        } else if (node instanceof Invoke) {
            processNodeInternal(((Invoke) node).callTarget(), state, effects, lastFixedNode);
        }
        return processNodeInternal(node, state, effects, lastFixedNode);
    }

    private boolean processNodeInternal(Node node, BlockT state, GraphEffectList effects, FixedWithNextNode lastFixedNode) {
        FixedNode nextFixedNode = lastFixedNode == null ? null : lastFixedNode.next();
        VirtualUtil.trace(node.getOptions(), debug, "%s", node);

        if (requiresProcessing(node)) {
            if (processVirtualizable((ValueNode) node, nextFixedNode, state, effects) == false) {
                return false;
            }
            if (tool.isDeleted()) {
                VirtualUtil.trace(node.getOptions(), debug, "deleted virtualizable allocation %s", node);
                return true;
            }
        }
        if (hasVirtualInputs.isMarked(node) && node instanceof ValueNode) {
            if (node instanceof Virtualizable) {
                if (processVirtualizable((ValueNode) node, nextFixedNode, state, effects) == false) {
                    return false;
                }
                if (tool.isDeleted()) {
                    VirtualUtil.trace(node.getOptions(), debug, "deleted virtualizable node %s", node);
                    return true;
                }
            }
            processNodeInputs((ValueNode) node, nextFixedNode, state, effects);
        }

        if (hasScalarReplacedInputs(node) && node instanceof ValueNode) {
            if (processNodeWithScalarReplacedInputs((ValueNode) node, nextFixedNode, state, effects)) {
                return true;
            }
        }
        return false;
    }

    protected boolean requiresProcessing(Node node) {
        return node instanceof VirtualizableAllocation;
    }

    private boolean processVirtualizable(ValueNode node, FixedNode insertBefore, BlockT state, GraphEffectList effects) {
        tool.reset(state, node, insertBefore, effects);
        return virtualize(node, tool);
    }

    protected boolean virtualize(ValueNode node, VirtualizerTool vt) {
        ((Virtualizable) node).virtualize(vt);
        return true; // request further processing
    }

    
This tries to canonicalize the node based on improved (replaced) inputs.
/**
     * This tries to canonicalize the node based on improved (replaced) inputs.
     */
    @SuppressWarnings("unchecked")
    private boolean processNodeWithScalarReplacedInputs(ValueNode node, FixedNode insertBefore, BlockT state, GraphEffectList effects) {
        ValueNode canonicalizedValue = node;
        if (node instanceof Canonicalizable.Unary<?>) {
            Canonicalizable.Unary<ValueNode> canonicalizable = (Canonicalizable.Unary<ValueNode>) node;
            ObjectState valueObj = getObjectState(state, canonicalizable.getValue());
            ValueNode valueAlias = valueObj != null ? valueObj.getMaterializedValue() : getScalarAlias(canonicalizable.getValue());
            if (valueAlias != canonicalizable.getValue()) {
                canonicalizedValue = (ValueNode) canonicalizable.canonical(tool, valueAlias);
            }
        } else if (node instanceof Canonicalizable.Binary<?>) {
            Canonicalizable.Binary<ValueNode> canonicalizable = (Canonicalizable.Binary<ValueNode>) node;
            ObjectState xObj = getObjectState(state, canonicalizable.getX());
            ValueNode xAlias = xObj != null ? xObj.getMaterializedValue() : getScalarAlias(canonicalizable.getX());
            ObjectState yObj = getObjectState(state, canonicalizable.getY());
            ValueNode yAlias = yObj != null ? yObj.getMaterializedValue() : getScalarAlias(canonicalizable.getY());
            if (xAlias != canonicalizable.getX() || yAlias != canonicalizable.getY()) {
                canonicalizedValue = (ValueNode) canonicalizable.canonical(tool, xAlias, yAlias);
            }
        } else {
            return false;
        }
        if (canonicalizedValue != node && canonicalizedValue != null) {
            if (canonicalizedValue.isAlive()) {
                ValueNode alias = getAliasAndResolve(state, canonicalizedValue);
                if (alias instanceof VirtualObjectNode) {
                    addVirtualAlias((VirtualObjectNode) alias, node);
                    effects.deleteNode(node);
                } else {
                    effects.replaceAtUsages(node, alias, insertBefore);
                    addScalarAlias(node, alias);
                }
            } else {
                if (!prepareCanonicalNode(canonicalizedValue, state, effects)) {
                    VirtualUtil.trace(node.getOptions(), debug, "replacement via canonicalization too complex: %s -> %s", node, canonicalizedValue);
                    return false;
                }
                if (canonicalizedValue instanceof ControlSinkNode) {
                    effects.replaceWithSink((FixedWithNextNode) node, (ControlSinkNode) canonicalizedValue);
                    state.markAsDead();
                } else {
                    effects.replaceAtUsages(node, canonicalizedValue, insertBefore);
                    addScalarAlias(node, canonicalizedValue);
                }
            }
            VirtualUtil.trace(node.getOptions(), debug, "replaced via canonicalization: %s -> %s", node, canonicalizedValue);
            return true;
        }
        return false;
    }

    
Nodes created during canonicalizations need to be scanned for values that were replaced.
/**
     * Nodes created during canonicalizations need to be scanned for values that were replaced.
     */
    private boolean prepareCanonicalNode(ValueNode node, BlockT state, GraphEffectList effects) {
        assert !node.isAlive();
        for (Position pos : node.inputPositions()) {
            Node input = pos.get(node);
            if (input instanceof ValueNode) {
                if (input.isAlive()) {
                    if (!(input instanceof VirtualObjectNode)) {
                        ObjectState obj = getObjectState(state, (ValueNode) input);
                        if (obj != null) {
                            if (obj.isVirtual()) {
                                return false;
                            } else {
                                pos.initialize(node, obj.getMaterializedValue());
                            }
                        } else {
                            pos.initialize(node, getScalarAlias((ValueNode) input));
                        }
                    }
                } else {
                    if (!prepareCanonicalNode((ValueNode) input, state, effects)) {
                        return false;
                    }
                }
            }
        }
        return true;
    }

    
This replaces all inputs that point to virtual or materialized values with the actual value, materializing if necessary. Also takes care of frame states, adding the necessary VirtualObjectState. /**
     * This replaces all inputs that point to virtual or materialized values with the actual value,
     * materializing if necessary. Also takes care of frame states, adding the necessary
     * {@link VirtualObjectState}.
     */
    private void processNodeInputs(ValueNode node, FixedNode insertBefore, BlockT state, GraphEffectList effects) {
        VirtualUtil.trace(node.getOptions(), debug, "processing nodewithstate: %s", node);
        for (Node input : node.inputs()) {
            if (input instanceof ValueNode) {
                ValueNode alias = getAlias((ValueNode) input);
                if (alias instanceof VirtualObjectNode) {
                    int id = ((VirtualObjectNode) alias).getObjectId();
                    ensureMaterialized(state, id, insertBefore, effects, COUNTER_MATERIALIZATIONS_UNHANDLED);
                    effects.replaceFirstInput(node, input, state.getObjectState(id).getMaterializedValue());
                    VirtualUtil.trace(node.getOptions(), debug, "replacing input %s at %s", input, node);
                }
            }
        }
        if (node instanceof NodeWithState) {
            processNodeWithState((NodeWithState) node, state, effects);
        }
    }

    private void processNodeWithState(NodeWithState nodeWithState, BlockT state, GraphEffectList effects) {
        for (FrameState fs : nodeWithState.states()) {
            FrameState frameState = getUniqueFramestate(nodeWithState, fs);
            EconomicSet<VirtualObjectNode> virtual = EconomicSet.create(Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE);
            frameState.applyToNonVirtual(new CollectVirtualObjectsClosure(virtual, effects, state));
            collectLockedVirtualObjects(state, virtual);
            collectReferencedVirtualObjects(state, virtual);
            addVirtualMappings(frameState, virtual, state, effects);
        }
    }

    private static FrameState getUniqueFramestate(NodeWithState nodeWithState, FrameState frameState) {
        if (frameState.hasMoreThanOneUsage()) {
            // Can happen for example from inlined snippets with multiple state split nodes.
            FrameState copy = (FrameState) frameState.copyWithInputs();
            nodeWithState.asNode().replaceFirstInput(frameState, copy);
            return copy;
        }
        return frameState;
    }

    private void addVirtualMappings(FrameState frameState, EconomicSet<VirtualObjectNode> virtual, BlockT state, GraphEffectList effects) {
        for (VirtualObjectNode obj : virtual) {
            effects.addVirtualMapping(frameState, state.getObjectState(obj).createEscapeObjectState(debug, obj));
        }
    }

    private void collectReferencedVirtualObjects(BlockT state, EconomicSet<VirtualObjectNode> virtual) {
        Iterator<VirtualObjectNode> iterator = virtual.iterator();
        while (iterator.hasNext()) {
            VirtualObjectNode object = iterator.next();
            int id = object.getObjectId();
            if (id != -1) {
                ObjectState objState = state.getObjectStateOptional(id);
                if (objState != null && objState.isVirtual()) {
                    for (ValueNode entry : objState.getEntries()) {
                        if (entry instanceof VirtualObjectNode) {
                            VirtualObjectNode entryVirtual = (VirtualObjectNode) entry;
                            if (!virtual.contains(entryVirtual)) {
                                virtual.add(entryVirtual);
                            }
                        }
                    }
                }
            }
        }
    }

    private void collectLockedVirtualObjects(BlockT state, EconomicSet<VirtualObjectNode> virtual) {
        for (int i = 0; i < state.getStateCount(); i++) {
            ObjectState objState = state.getObjectStateOptional(i);
            if (objState != null && objState.isVirtual() && objState.hasLocks()) {
                virtual.add(virtualObjects.get(i));
            }
        }
    }

    
Returns:
true if materialization happened, false if not./**
     * @return true if materialization happened, false if not.
     */
    protected boolean ensureMaterialized(PartialEscapeBlockState<?> state, int object, FixedNode materializeBefore, GraphEffectList effects, CounterKey counter) {
        if (state.getObjectState(object).isVirtual()) {
            counter.increment(debug);
            VirtualObjectNode virtual = virtualObjects.get(object);
            state.materializeBefore(materializeBefore, virtual, effects);
            assert !updateStatesForMaterialized(state, virtual, state.getObjectState(object).getMaterializedValue()) : "method must already have been called before";
            return true;
        } else {
            return false;
        }
    }

    public static boolean updateStatesForMaterialized(PartialEscapeBlockState<?> state, VirtualObjectNode virtual, ValueNode materializedValue) {
        // update all existing states with the newly materialized object
        boolean change = false;
        for (int i = 0; i < state.getStateCount(); i++) {
            ObjectState objState = state.getObjectStateOptional(i);
            if (objState != null && objState.isVirtual()) {
                ValueNode[] entries = objState.getEntries();
                for (int i2 = 0; i2 < entries.length; i2++) {
                    if (entries[i2] == virtual) {
                        state.setEntry(i, i2, materializedValue);
                        change = true;
                    }
                }
            }
        }
        return change;
    }

    @Override
    protected BlockT stripKilledLoopLocations(Loop<Block> loop, BlockT originalInitialState) {
        BlockT initialState = super.stripKilledLoopLocations(loop, originalInitialState);
        if (loop.getDepth() > GraalOptions.EscapeAnalysisLoopCutoff.getValue(cfg.graph.getOptions())) {
            /*
             * After we've reached the maximum loop nesting, we'll simply materialize everything we
             * can to make sure that the loops only need to be iterated one time. Care is taken here
             * to not materialize virtual objects that have the "ensureVirtualized" flag set.
             */
            LoopBeginNode loopBegin = (LoopBeginNode) loop.getHeader().getBeginNode();
            AbstractEndNode end = loopBegin.forwardEnd();
            Block loopPredecessor = loop.getHeader().getFirstPredecessor();
            assert loopPredecessor.getEndNode() == end;
            int length = initialState.getStateCount();

            boolean change;
            BitSet ensureVirtualized = new BitSet(length);
            for (int i = 0; i < length; i++) {
                ObjectState state = initialState.getObjectStateOptional(i);
                if (state != null && state.isVirtual() && state.getEnsureVirtualized()) {
                    ensureVirtualized.set(i);
                }
            }
            do {
                // propagate "ensureVirtualized" flag
                change = false;
                for (int i = 0; i < length; i++) {
                    if (!ensureVirtualized.get(i)) {
                        ObjectState state = initialState.getObjectStateOptional(i);
                        if (state != null && state.isVirtual()) {
                            for (ValueNode entry : state.getEntries()) {
                                if (entry instanceof VirtualObjectNode) {
                                    if (ensureVirtualized.get(((VirtualObjectNode) entry).getObjectId())) {
                                        change = true;
                                        ensureVirtualized.set(i);
                                        break;
                                    }
                                }
                            }
                        }
                    }
                }
            } while (change);

            for (int i = 0; i < length; i++) {
                ObjectState state = initialState.getObjectStateOptional(i);
                if (state != null && state.isVirtual() && !ensureVirtualized.get(i)) {
                    initialState.materializeBefore(end, virtualObjects.get(i), blockEffects.get(loopPredecessor));
                }
            }
        }
        return initialState;
    }

    @Override
    protected void processInitialLoopState(Loop<Block> loop, BlockT initialState) {
        for (PhiNode phi : ((LoopBeginNode) loop.getHeader().getBeginNode()).phis()) {
            if (phi.valueAt(0) != null) {
                ValueNode alias = getAliasAndResolve(initialState, phi.valueAt(0));
                if (alias instanceof VirtualObjectNode) {
                    VirtualObjectNode virtual = (VirtualObjectNode) alias;
                    addVirtualAlias(virtual, phi);
                } else {
                    aliases.set(phi, null);
                }
            }
        }
    }

    @Override
    protected void processLoopExit(LoopExitNode exitNode, BlockT initialState, BlockT exitState, GraphEffectList effects) {
        if (exitNode.graph().hasValueProxies()) {
            EconomicMap<Integer, ProxyNode> proxies = EconomicMap.create(Equivalence.DEFAULT);
            for (ProxyNode proxy : exitNode.proxies()) {
                ValueNode alias = getAlias(proxy.value());
                if (alias instanceof VirtualObjectNode) {
                    VirtualObjectNode virtual = (VirtualObjectNode) alias;
                    proxies.put(virtual.getObjectId(), proxy);
                }
            }
            for (int i = 0; i < exitState.getStateCount(); i++) {
                ObjectState exitObjState = exitState.getObjectStateOptional(i);
                if (exitObjState != null) {
                    ObjectState initialObjState = initialState.getObjectStateOptional(i);

                    if (exitObjState.isVirtual()) {
                        processVirtualAtLoopExit(exitNode, effects, i, exitObjState, initialObjState, exitState);
                    } else {
                        processMaterializedAtLoopExit(exitNode, effects, proxies, i, exitObjState, initialObjState, exitState);
                    }
                }
            }
        }
    }

    private static void processMaterializedAtLoopExit(LoopExitNode exitNode, GraphEffectList effects, EconomicMap<Integer, ProxyNode> proxies, int object, ObjectState exitObjState,
                    ObjectState initialObjState, PartialEscapeBlockState<?> exitState) {
        if (initialObjState == null || initialObjState.isVirtual()) {
            ProxyNode proxy = proxies.get(object);
            if (proxy == null) {
                proxy = new ValueProxyNode(exitObjState.getMaterializedValue(), exitNode);
                effects.addFloatingNode(proxy, "proxy");
            } else {
                effects.replaceFirstInput(proxy, proxy.value(), exitObjState.getMaterializedValue());
                // nothing to do - will be handled in processNode
            }
            exitState.updateMaterializedValue(object, proxy);
        } else {
            if (initialObjState.getMaterializedValue() != exitObjState.getMaterializedValue()) {
                exitNode.getDebug().log("materialized value changes within loop: %s vs. %s at %s", initialObjState.getMaterializedValue(), exitObjState.getMaterializedValue(), exitNode);
            }
        }
    }

    private static void processVirtualAtLoopExit(LoopExitNode exitNode, GraphEffectList effects, int object, ObjectState exitObjState, ObjectState initialObjState,
                    PartialEscapeBlockState<?> exitState) {
        for (int i = 0; i < exitObjState.getEntries().length; i++) {
            ValueNode value = exitState.getObjectState(object).getEntry(i);
            if (!(value instanceof VirtualObjectNode || value.isConstant())) {
                if (exitNode.loopBegin().isPhiAtMerge(value) || initialObjState == null || !initialObjState.isVirtual() || initialObjState.getEntry(i) != value) {
                    ProxyNode proxy = new ValueProxyNode(value, exitNode);
                    exitState.setEntry(object, i, proxy);
                    effects.addFloatingNode(proxy, "virtualProxy");
                }
            }
        }
    }

    @Override
    protected MergeProcessor createMergeProcessor(Block merge) {
        return new MergeProcessor(merge);
    }

    protected class MergeProcessor extends EffectsClosure<BlockT>.MergeProcessor {

        private EconomicMap<Object, ValuePhiNode> materializedPhis;
        private EconomicMap<ValueNode, ValuePhiNode[]> valuePhis;
        private EconomicMap<ValuePhiNode, VirtualObjectNode> valueObjectVirtuals;
        private final boolean needsCaching;

        public MergeProcessor(Block mergeBlock) {
            super(mergeBlock);
            // merge will only be called multiple times for loop headers
            needsCaching = mergeBlock.isLoopHeader();
        }

        protected <T> PhiNode getPhi(T virtual, Stamp stamp) {
            if (needsCaching) {
                return getPhiCached(virtual, stamp);
            } else {
                return createValuePhi(stamp);
            }
        }

        private <T> PhiNode getPhiCached(T virtual, Stamp stamp) {
            if (materializedPhis == null) {
                materializedPhis = EconomicMap.create(Equivalence.DEFAULT);
            }
            ValuePhiNode result = materializedPhis.get(virtual);
            if (result == null) {
                result = createValuePhi(stamp);
                materializedPhis.put(virtual, result);
            }
            return result;
        }

        private PhiNode[] getValuePhis(ValueNode key, int entryCount) {
            if (needsCaching) {
                return getValuePhisCached(key, entryCount);
            } else {
                return new ValuePhiNode[entryCount];
            }
        }

        private PhiNode[] getValuePhisCached(ValueNode key, int entryCount) {
            if (valuePhis == null) {
                valuePhis = EconomicMap.create(Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE);
            }
            ValuePhiNode[] result = valuePhis.get(key);
            if (result == null) {
                result = new ValuePhiNode[entryCount];
                valuePhis.put(key, result);
            }
            assert result.length == entryCount;
            return result;
        }

        private VirtualObjectNode getValueObjectVirtual(ValuePhiNode phi, VirtualObjectNode virtual) {
            if (needsCaching) {
                return getValueObjectVirtualCached(phi, virtual);
            } else {
                VirtualObjectNode duplicate = virtual.duplicate();
                duplicate.setNodeSourcePosition(virtual.getNodeSourcePosition());
                return duplicate;
            }
        }

        private VirtualObjectNode getValueObjectVirtualCached(ValuePhiNode phi, VirtualObjectNode virtual) {
            if (valueObjectVirtuals == null) {
                valueObjectVirtuals = EconomicMap.create(Equivalence.IDENTITY);
            }
            VirtualObjectNode result = valueObjectVirtuals.get(phi);
            if (result == null) {
                result = virtual.duplicate();
                result.setNodeSourcePosition(virtual.getNodeSourcePosition());
                valueObjectVirtuals.put(phi, result);
            }
            return result;
        }

        
Merge all predecessor block states into one block state. This is an iterative process,
because merging states can lead to materializations which make previous parts of the
merging operation invalid. The merging process is executed until a stable state has been
reached. This method needs to be careful to place the effects of the merging operation
into the correct blocks.
Params:
statesList – the predecessor block states of the merge/**
         * Merge all predecessor block states into one block state. This is an iterative process,
         * because merging states can lead to materializations which make previous parts of the
         * merging operation invalid. The merging process is executed until a stable state has been
         * reached. This method needs to be careful to place the effects of the merging operation
         * into the correct blocks.
         *
         * @param statesList the predecessor block states of the merge
         */
        @Override
        protected void merge(List<BlockT> statesList) {

            PartialEscapeBlockState<?>[] states = new PartialEscapeBlockState<?>[statesList.size()];
            for (int i = 0; i < statesList.size(); i++) {
                states[i] = statesList.get(i);
            }

            // calculate the set of virtual objects that exist in all predecessors
            int[] virtualObjTemp = intersectVirtualObjects(states);

            boolean materialized;
            do {
                materialized = false;

                if (PartialEscapeBlockState.identicalObjectStates(states)) {
                    newState.adoptAddObjectStates(states[0]);
                } else {

                    for (int object : virtualObjTemp) {
                        if (PartialEscapeBlockState.identicalObjectStates(states, object)) {
                            newState.addObject(object, states[0].getObjectState(object).share());
                            continue;
                        }

                        // determine if all inputs are virtual or the same materialized value
                        int virtualCount = 0;
                        ObjectState startObj = states[0].getObjectState(object);
                        boolean locksMatch = true;
                        boolean ensureVirtual = true;
                        ValueNode uniqueMaterializedValue = startObj.isVirtual() ? null : startObj.getMaterializedValue();
                        for (int i = 0; i < states.length; i++) {
                            ObjectState obj = states[i].getObjectState(object);
                            ensureVirtual &= obj.getEnsureVirtualized();
                            if (obj.isVirtual()) {
                                virtualCount++;
                                uniqueMaterializedValue = null;
                                locksMatch &= obj.locksEqual(startObj);
                            } else if (obj.getMaterializedValue() != uniqueMaterializedValue) {
                                uniqueMaterializedValue = null;
                            }
                        }

                        if (virtualCount == states.length && locksMatch) {
                            materialized |= mergeObjectStates(object, null, states);
                        } else {
                            if (uniqueMaterializedValue != null) {
                                newState.addObject(object, new ObjectState(uniqueMaterializedValue, null, ensureVirtual));
                            } else {
                                PhiNode materializedValuePhi = getPhi(object, StampFactory.forKind(JavaKind.Object));
                                mergeEffects.addFloatingNode(materializedValuePhi, "materializedPhi");
                                for (int i = 0; i < states.length; i++) {
                                    ObjectState obj = states[i].getObjectState(object);
                                    if (obj.isVirtual()) {
                                        Block predecessor = getPredecessor(i);
                                        if (!ensureVirtual && obj.isVirtual()) {
                                            // we can materialize if not all inputs are
                                            // "ensureVirtualized"
                                            obj.setEnsureVirtualized(false);
                                        }
                                        materialized |= ensureMaterialized(states[i], object, predecessor.getEndNode(), blockEffects.get(predecessor), COUNTER_MATERIALIZATIONS_MERGE);
                                        obj = states[i].getObjectState(object);
                                    }
                                    setPhiInput(materializedValuePhi, i, obj.getMaterializedValue());
                                }
                                newState.addObject(object, new ObjectState(materializedValuePhi, null, false));
                            }
                        }
                    }
                }

                for (PhiNode phi : getPhis()) {
                    aliases.set(phi, null);
                    if (hasVirtualInputs.isMarked(phi) && phi instanceof ValuePhiNode) {
                        materialized |= processPhi((ValuePhiNode) phi, states);
                    }
                }
                if (materialized) {
                    newState.resetObjectStates(virtualObjects.size());
                    mergeEffects.clear();
                    afterMergeEffects.clear();
                }
            } while (materialized);
        }

        private int[] intersectVirtualObjects(PartialEscapeBlockState<?>[] states) {
            int length = states[0].getStateCount();
            for (int i = 1; i < states.length; i++) {
                length = Math.min(length, states[i].getStateCount());
            }

            int count = 0;
            for (int objectIndex = 0; objectIndex < length; objectIndex++) {
                if (intersectObjectState(states, objectIndex)) {
                    count++;
                }
            }

            int index = 0;
            int[] resultInts = new int[count];
            for (int objectIndex = 0; objectIndex < length; objectIndex++) {
                if (intersectObjectState(states, objectIndex)) {
                    resultInts[index++] = objectIndex;
                }
            }
            assert index == count;
            return resultInts;
        }

        private boolean intersectObjectState(PartialEscapeBlockState<?>[] states, int objectIndex) {
            for (int i = 0; i < states.length; i++) {
                PartialEscapeBlockState<?> state = states[i];
                if (state.getObjectStateOptional(objectIndex) == null) {
                    return false;
                }
            }
            return true;
        }

        
Try to merge multiple virtual object states into a single object state. If the incoming object states are compatible, then this method will create PhiNodes for the object's entries where needed. If they are incompatible, then all incoming virtual objects will be materialized, and a PhiNode for the materialized values will be created. Object states can be incompatible if they contain long or double values occupying two int slots in such a way that that their values cannot be merged using PhiNodes. 
Params:
states – the predecessor block states of the merge
Returns:
true if materialization happened during the merge, false otherwise/**
         * Try to merge multiple virtual object states into a single object state. If the incoming
         * object states are compatible, then this method will create PhiNodes for the object's
         * entries where needed. If they are incompatible, then all incoming virtual objects will be
         * materialized, and a PhiNode for the materialized values will be created. Object states
         * can be incompatible if they contain {@code long} or {@code double} values occupying two
         * {@code int} slots in such a way that that their values cannot be merged using PhiNodes.
         *
         * @param states the predecessor block states of the merge
         * @return true if materialization happened during the merge, false otherwise
         */
        private boolean mergeObjectStates(int resultObject, int[] sourceObjects, PartialEscapeBlockState<?>[] states) {
            boolean compatible = true;
            boolean ensureVirtual = true;
            IntUnaryOperator getObject = index -> sourceObjects == null ? resultObject : sourceObjects[index];

            VirtualObjectNode virtual = virtualObjects.get(resultObject);
            int entryCount = virtual.entryCount();

            // determine all entries that have a two-slot value
            JavaKind[] twoSlotKinds = null;
            outer: for (int i = 0; i < states.length; i++) {
                ObjectState objectState = states[i].getObjectState(getObject.applyAsInt(i));
                ValueNode[] entries = objectState.getEntries();
                int valueIndex = 0;
                ensureVirtual &= objectState.getEnsureVirtualized();
                while (valueIndex < entryCount) {
                    JavaKind otherKind = entries[valueIndex].getStackKind();
                    JavaKind entryKind = virtual.entryKind(valueIndex);
                    if (entryKind == JavaKind.Int && otherKind.needsTwoSlots()) {
                        if (twoSlotKinds == null) {
                            twoSlotKinds = new JavaKind[entryCount];
                        }
                        if (twoSlotKinds[valueIndex] != null && twoSlotKinds[valueIndex] != otherKind) {
                            compatible = false;
                            break outer;
                        }
                        twoSlotKinds[valueIndex] = otherKind;
                        // skip the next entry
                        valueIndex++;
                    } else {
                        assert entryKind.getStackKind() == otherKind.getStackKind() || (entryKind == JavaKind.Int && otherKind == JavaKind.Illegal) ||
                                        entryKind.getBitCount() >= otherKind.getBitCount() : entryKind + " vs " + otherKind;
                    }
                    valueIndex++;
                }
            }
            if (compatible && twoSlotKinds != null) {
                // if there are two-slot values then make sure the incoming states can be merged
                outer: for (int valueIndex = 0; valueIndex < entryCount; valueIndex++) {
                    if (twoSlotKinds[valueIndex] != null) {
                        assert valueIndex < virtual.entryCount() - 1 && virtual.entryKind(valueIndex) == JavaKind.Int && virtual.entryKind(valueIndex + 1) == JavaKind.Int;
                        for (int i = 0; i < states.length; i++) {
                            int object = getObject.applyAsInt(i);
                            ObjectState objectState = states[i].getObjectState(object);
                            ValueNode value = objectState.getEntry(valueIndex);
                            JavaKind valueKind = value.getStackKind();
                            if (valueKind != twoSlotKinds[valueIndex]) {
                                ValueNode nextValue = objectState.getEntry(valueIndex + 1);
                                if (value.isConstant() && value.asConstant().equals(JavaConstant.INT_0) && nextValue.isConstant() && nextValue.asConstant().equals(JavaConstant.INT_0)) {
                                    // rewrite to a zero constant of the larger kind
                                    debug.log("Rewriting entry %s to constant of larger size", valueIndex);
                                    states[i].setEntry(object, valueIndex, ConstantNode.defaultForKind(twoSlotKinds[valueIndex], graph()));
                                    states[i].setEntry(object, valueIndex + 1, ConstantNode.forConstant(JavaConstant.forIllegal(), tool.getMetaAccess(), graph()));
                                } else {
                                    compatible = false;
                                    break outer;
                                }
                            }
                        }
                    }
                }
            }

            if (compatible) {
                // virtual objects are compatible: create phis for all entries that need them
                ValueNode[] values = states[0].getObjectState(getObject.applyAsInt(0)).getEntries().clone();
                PhiNode[] phis = getValuePhis(virtual, virtual.entryCount());
                int valueIndex = 0;
                while (valueIndex < values.length) {
                    for (int i = 1; i < states.length; i++) {
                        if (phis[valueIndex] == null) {
                            ValueNode field = states[i].getObjectState(getObject.applyAsInt(i)).getEntry(valueIndex);
                            if (values[valueIndex] != field) {
                                phis[valueIndex] = createValuePhi(values[valueIndex].stamp(NodeView.DEFAULT).unrestricted());
                            }
                        }
                    }
                    if (phis[valueIndex] != null && !phis[valueIndex].stamp(NodeView.DEFAULT).isCompatible(values[valueIndex].stamp(NodeView.DEFAULT))) {
                        phis[valueIndex] = createValuePhi(values[valueIndex].stamp(NodeView.DEFAULT).unrestricted());
                    }
                    if (twoSlotKinds != null && twoSlotKinds[valueIndex] != null) {
                        // skip an entry after a long/double value that occupies two int slots
                        valueIndex++;
                        phis[valueIndex] = null;
                        values[valueIndex] = ConstantNode.forConstant(JavaConstant.forIllegal(), tool.getMetaAccess(), graph());
                    }
                    valueIndex++;
                }

                boolean materialized = false;
                for (int i = 0; i < values.length; i++) {
                    PhiNode phi = phis[i];
                    if (phi != null) {
                        mergeEffects.addFloatingNode(phi, "virtualMergePhi");
                        if (virtual.entryKind(i) == JavaKind.Object) {
                            materialized |= mergeObjectEntry(getObject, states, phi, i);
                        } else {
                            for (int i2 = 0; i2 < states.length; i2++) {
                                ObjectState state = states[i2].getObjectState(getObject.applyAsInt(i2));
                                if (!state.isVirtual()) {
                                    break;
                                }
                                setPhiInput(phi, i2, state.getEntry(i));
                            }
                        }
                        values[i] = phi;
                    }
                }
                newState.addObject(resultObject, new ObjectState(values, states[0].getObjectState(getObject.applyAsInt(0)).getLocks(), ensureVirtual));
                return materialized;
            } else {
                // not compatible: materialize in all predecessors
                PhiNode materializedValuePhi = getPhi(resultObject, StampFactory.forKind(JavaKind.Object));
                for (int i = 0; i < states.length; i++) {
                    Block predecessor = getPredecessor(i);
                    if (!ensureVirtual && states[i].getObjectState(getObject.applyAsInt(i)).isVirtual()) {
                        // we can materialize if not all inputs are "ensureVirtualized"
                        states[i].getObjectState(getObject.applyAsInt(i)).setEnsureVirtualized(false);
                    }
                    ensureMaterialized(states[i], getObject.applyAsInt(i), predecessor.getEndNode(), blockEffects.get(predecessor), COUNTER_MATERIALIZATIONS_MERGE);
                    setPhiInput(materializedValuePhi, i, states[i].getObjectState(getObject.applyAsInt(i)).getMaterializedValue());
                }
                newState.addObject(resultObject, new ObjectState(materializedValuePhi, null, ensureVirtual));
                return true;
            }
        }

        
Fill the inputs of the PhiNode corresponding to one JavaKind.Object entry in the virtual object. 
Returns:
true if materialization happened during the merge, false otherwise/**
         * Fill the inputs of the PhiNode corresponding to one {@link JavaKind#Object} entry in the
         * virtual object.
         *
         * @return true if materialization happened during the merge, false otherwise
         */
        private boolean mergeObjectEntry(IntUnaryOperator objectIdFunc, PartialEscapeBlockState<?>[] states, PhiNode phi, int entryIndex) {
            boolean materialized = false;
            for (int i = 0; i < states.length; i++) {
                int object = objectIdFunc.applyAsInt(i);
                ObjectState objectState = states[i].getObjectState(object);
                if (!objectState.isVirtual()) {
                    break;
                }
                ValueNode entry = objectState.getEntry(entryIndex);
                if (entry instanceof VirtualObjectNode) {
                    VirtualObjectNode entryVirtual = (VirtualObjectNode) entry;
                    Block predecessor = getPredecessor(i);
                    materialized |= ensureMaterialized(states[i], entryVirtual.getObjectId(), predecessor.getEndNode(), blockEffects.get(predecessor), COUNTER_MATERIALIZATIONS_MERGE);
                    objectState = states[i].getObjectState(object);
                    if (objectState.isVirtual()) {
                        states[i].setEntry(object, entryIndex, entry = states[i].getObjectState(entryVirtual.getObjectId()).getMaterializedValue());
                    }
                }
                setPhiInput(phi, i, entry);
            }
            return materialized;
        }

        
Examine a PhiNode and try to replace it with merging of virtual objects if all its inputs
refer to virtual object states. In order for the merging to happen, all incoming object
states need to be compatible and without object identity (meaning that their object
identity if not used later on).
Params:
phi – the PhiNode that should be processed
states – the predecessor block states of the merge
Returns:
true if materialization happened during the merge, false otherwise/**
         * Examine a PhiNode and try to replace it with merging of virtual objects if all its inputs
         * refer to virtual object states. In order for the merging to happen, all incoming object
         * states need to be compatible and without object identity (meaning that their object
         * identity if not used later on).
         *
         * @param phi the PhiNode that should be processed
         * @param states the predecessor block states of the merge
         * @return true if materialization happened during the merge, false otherwise
         */
        private boolean processPhi(ValuePhiNode phi, PartialEscapeBlockState<?>[] states) {

            // determine how many inputs are virtual and if they're all the same virtual object
            int virtualInputs = 0;
            boolean uniqueVirtualObject = true;
            boolean ensureVirtual = true;
            VirtualObjectNode[] virtualObjs = new VirtualObjectNode[states.length];
            for (int i = 0; i < states.length; i++) {
                ValueNode alias = getAlias(getPhiValueAt(phi, i));
                if (alias instanceof VirtualObjectNode) {
                    VirtualObjectNode virtual = (VirtualObjectNode) alias;
                    virtualObjs[i] = virtual;
                    ObjectState objectState = states[i].getObjectStateOptional(virtual);
                    if (objectState == null) {
                        assert getPhiValueAt(phi, i) instanceof PhiNode : "this should only happen for phi nodes";
                        return false;
                    }
                    if (objectState.isVirtual()) {
                        if (virtualObjs[0] != alias) {
                            uniqueVirtualObject = false;
                        }
                        ensureVirtual &= objectState.getEnsureVirtualized();
                        virtualInputs++;
                    }
                }
            }
            if (virtualInputs == states.length) {
                if (uniqueVirtualObject) {
                    // all inputs refer to the same object: just make the phi node an alias
                    addVirtualAlias(virtualObjs[0], phi);
                    mergeEffects.deleteNode(phi);
                    return false;
                } else {
                    // all inputs are virtual: check if they're compatible and without identity
                    boolean compatible = true;
                    VirtualObjectNode firstVirtual = virtualObjs[0];
                    for (int i = 0; i < states.length; i++) {
                        VirtualObjectNode virtual = virtualObjs[i];

                        if (!firstVirtual.type().equals(virtual.type()) || firstVirtual.entryCount() != virtual.entryCount()) {
                            compatible = false;
                            break;
                        }
                        if (!states[0].getObjectState(firstVirtual).locksEqual(states[i].getObjectState(virtual))) {
                            compatible = false;
                            break;
                        }
                    }
                    if (compatible) {
                        for (int i = 0; i < states.length; i++) {
                            VirtualObjectNode virtual = virtualObjs[i];
                            /*
                             * check whether we trivially see that this is the only reference to
                             * this allocation
                             */
                            if (virtual.hasIdentity() && !isSingleUsageAllocation(getPhiValueAt(phi, i), virtualObjs, states[i])) {
                                compatible = false;
                            }
                        }
                    }
                    if (compatible) {
                        VirtualObjectNode virtual = getValueObjectVirtual(phi, virtualObjs[0]);
                        mergeEffects.addFloatingNode(virtual, "valueObjectNode");
                        mergeEffects.deleteNode(phi);
                        if (virtual.getObjectId() == -1) {
                            int id = virtualObjects.size();
                            virtualObjects.add(virtual);
                            virtual.setObjectId(id);
                        }

                        int[] virtualObjectIds = new int[states.length];
                        for (int i = 0; i < states.length; i++) {
                            virtualObjectIds[i] = virtualObjs[i].getObjectId();
                        }
                        boolean materialized = mergeObjectStates(virtual.getObjectId(), virtualObjectIds, states);
                        addVirtualAlias(virtual, virtual);
                        addVirtualAlias(virtual, phi);
                        return materialized;
                    }
                }
            }

            // otherwise: materialize all phi inputs
            boolean materialized = false;
            if (virtualInputs > 0) {
                for (int i = 0; i < states.length; i++) {
                    VirtualObjectNode virtual = virtualObjs[i];
                    if (virtual != null) {
                        Block predecessor = getPredecessor(i);
                        if (!ensureVirtual && states[i].getObjectState(virtual).isVirtual()) {
                            // we can materialize if not all inputs are "ensureVirtualized"
                            states[i].getObjectState(virtual).setEnsureVirtualized(false);
                        }
                        materialized |= ensureMaterialized(states[i], virtual.getObjectId(), predecessor.getEndNode(), blockEffects.get(predecessor), COUNTER_MATERIALIZATIONS_PHI);
                    }
                }
            }
            for (int i = 0; i < states.length; i++) {
                VirtualObjectNode virtual = virtualObjs[i];
                if (virtual != null) {
                    setPhiInput(phi, i, getAliasAndResolve(states[i], virtual));
                }
            }
            return materialized;
        }

        private boolean isSingleUsageAllocation(ValueNode value, VirtualObjectNode[] virtualObjs, PartialEscapeBlockState<?> state) {
            /*
             * If the phi input is an allocation, we know that it is a "fresh" value, i.e., that
             * this is a value that will only appear through this source, and cannot appear anywhere
             * else. If the phi is also the only usage of this input, we know that no other place
             * can check object identity against it, so it is safe to lose the object identity here.
             */
            if (!(value instanceof AllocatedObjectNode && value.hasExactlyOneUsage())) {
                return false;
            }

            /*
             * Check that the state only references the one virtual object from the Phi.
             */
            VirtualObjectNode singleVirtual = null;
            for (int v = 0; v < virtualObjs.length; v++) {
                if (state.contains(virtualObjs[v])) {
                    if (singleVirtual == null) {
                        singleVirtual = virtualObjs[v];
                    } else if (singleVirtual != virtualObjs[v]) {
                        /*
                         * More than one virtual object is visible in the object state.
                         */
                        return false;
                    }
                }
            }
            return true;
        }
    }

    public ObjectState getObjectState(PartialEscapeBlockState<?> state, ValueNode value) {
        if (value == null) {
            return null;
        }
        if (value.isAlive() && !aliases.isNew(value)) {
            ValueNode object = aliases.get(value);
            return object instanceof VirtualObjectNode ? state.getObjectStateOptional((VirtualObjectNode) object) : null;
        } else {
            if (value instanceof VirtualObjectNode) {
                return state.getObjectStateOptional((VirtualObjectNode) value);
            }
            return null;
        }
    }

    public ValueNode getAlias(ValueNode value) {
        if (value != null && !(value instanceof VirtualObjectNode)) {
            if (value.isAlive() && !aliases.isNew(value)) {
                ValueNode result = aliases.get(value);
                if (result != null) {
                    return result;
                }
            }
        }
        return value;
    }

    public ValueNode getAliasAndResolve(PartialEscapeBlockState<?> state, ValueNode value) {
        ValueNode result = getAlias(value);
        if (result instanceof VirtualObjectNode) {
            int id = ((VirtualObjectNode) result).getObjectId();
            if (id != -1 && !state.getObjectState(id).isVirtual()) {
                result = state.getObjectState(id).getMaterializedValue();
            }
        }
        return result;
    }

    void addVirtualAlias(VirtualObjectNode virtual, ValueNode node) {
        if (node.isAlive()) {
            aliases.set(node, virtual);
            for (Node usage : node.usages()) {
                markVirtualUsages(usage);
            }
        }
    }

    private void markVirtualUsages(Node node) {
        if (!hasVirtualInputs.isNew(node) && !hasVirtualInputs.isMarked(node)) {
            hasVirtualInputs.mark(node);
            if (node instanceof VirtualState) {
                for (Node usage : node.usages()) {
                    markVirtualUsages(usage);
                }
            }
        }
    }
}