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 * 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.
 *
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package org.graalvm.compiler.virtual.phases.ea;

import java.util.Arrays;
import java.util.List;

import org.graalvm.compiler.debug.CounterKey;
import org.graalvm.compiler.debug.DebugContext;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.java.MonitorIdNode;
import org.graalvm.compiler.nodes.virtual.EscapeObjectState;
import org.graalvm.compiler.nodes.virtual.LockState;
import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;
import org.graalvm.compiler.virtual.nodes.MaterializedObjectState;
import org.graalvm.compiler.virtual.nodes.VirtualObjectState;

import jdk.vm.ci.meta.JavaConstant;

This class describes the state of a virtual object while iterating over the graph. It describes
the fields or array elements (called "entries") and the lock count if the object is still
virtual. If the object was materialized, it contains the current materialized value.
/**
 * This class describes the state of a virtual object while iterating over the graph. It describes
 * the fields or array elements (called "entries") and the lock count if the object is still
 * virtual. If the object was materialized, it contains the current materialized value.
 */
public class ObjectState {

    public static final CounterKey CREATE_ESCAPED_OBJECT_STATE = DebugContext.counter("CreateEscapeObjectState");
    public static final CounterKey GET_ESCAPED_OBJECT_STATE = DebugContext.counter("GetEscapeObjectState");

    private ValueNode[] entries;
    private ValueNode materializedValue;
    private LockState locks;
    private boolean ensureVirtualized;

    private EscapeObjectState cachedState;

    
ObjectStates are duplicated lazily, if this field is true then the state needs to be copied
before it is modified.
/**
     * ObjectStates are duplicated lazily, if this field is true then the state needs to be copied
     * before it is modified.
     */
    boolean copyOnWrite;

    public ObjectState(ValueNode[] entries, List<MonitorIdNode> locks, boolean ensureVirtualized) {
        this(entries, (LockState) null, ensureVirtualized);
        for (int i = locks.size() - 1; i >= 0; i--) {
            this.locks = new LockState(locks.get(i), this.locks);
        }
    }

    public ObjectState(ValueNode[] entries, LockState locks, boolean ensureVirtualized) {
        assert checkIllegalValues(entries);
        this.entries = entries;
        this.locks = locks;
        this.ensureVirtualized = ensureVirtualized;
    }

    public ObjectState(ValueNode materializedValue, LockState locks, boolean ensureVirtualized) {
        assert materializedValue != null;
        this.materializedValue = materializedValue;
        this.locks = locks;
        this.ensureVirtualized = ensureVirtualized;
    }

    private ObjectState(ObjectState other) {
        entries = other.entries == null ? null : other.entries.clone();
        materializedValue = other.materializedValue;
        locks = other.locks;
        cachedState = other.cachedState;
        ensureVirtualized = other.ensureVirtualized;
    }

    public ObjectState cloneState() {
        return new ObjectState(this);
    }

    
Ensure that if an illegal value is seen that the previous value is a double word value. /**
     * Ensure that if an {@link JavaConstant#forIllegal() illegal value} is seen that the previous
     * value is a double word value.
     */
    public static boolean checkIllegalValues(ValueNode[] values) {
        if (values != null) {
            for (int v = 1; v < values.length; v++) {
                checkIllegalValue(values, v);
            }
        }
        return true;
    }

    
Ensure that if an illegal value is seen that the previous value is a double word value. /**
     * Ensure that if an {@link JavaConstant#forIllegal() illegal value} is seen that the previous
     * value is a double word value.
     */
    public static boolean checkIllegalValue(ValueNode[] values, int v) {
        if (v > 0 && values[v].isConstant() && values[v].asConstant().equals(JavaConstant.forIllegal())) {
            assert values[v - 1].getStackKind().needsTwoSlots();
        }
        return true;
    }

    public EscapeObjectState createEscapeObjectState(DebugContext debug, VirtualObjectNode virtual) {
        GET_ESCAPED_OBJECT_STATE.increment(debug);
        if (cachedState == null) {
            CREATE_ESCAPED_OBJECT_STATE.increment(debug);
            if (isVirtual()) {
                /*
                 * Clear out entries that are default values anyway.
                 *
                 * TODO: this should be propagated into ObjectState.entries, but that will take some
                 * more refactoring.
                 */
                ValueNode[] newEntries = entries.clone();
                for (int i = 0; i < newEntries.length; i++) {
                    if (newEntries[i].asJavaConstant() == JavaConstant.defaultForKind(virtual.entryKind(i).getStackKind())) {
                        newEntries[i] = null;
                    }
                }
                cachedState = new VirtualObjectState(virtual, newEntries);
            } else {
                cachedState = new MaterializedObjectState(virtual, materializedValue);
            }
        }
        return cachedState;

    }

    public boolean isVirtual() {
        assert materializedValue == null ^ entries == null;
        return materializedValue == null;
    }

    
Users of this method are not allowed to change the entries of the returned array.
/**
     * Users of this method are not allowed to change the entries of the returned array.
     */
    public ValueNode[] getEntries() {
        assert isVirtual();
        return entries;
    }

    public ValueNode getEntry(int index) {
        assert isVirtual();
        return entries[index];
    }

    public ValueNode getMaterializedValue() {
        assert !isVirtual();
        return materializedValue;
    }

    public void setEntry(int index, ValueNode value) {
        assert isVirtual();
        cachedState = null;
        entries[index] = value;
    }

    public void escape(ValueNode materialized) {
        assert isVirtual();
        assert materialized != null;
        materializedValue = materialized;
        entries = null;
        cachedState = null;
        assert !isVirtual();
    }

    public void updateMaterializedValue(ValueNode value) {
        assert !isVirtual();
        assert value != null;
        cachedState = null;
        materializedValue = value;
    }

    public void addLock(MonitorIdNode monitorId) {
        locks = new LockState(monitorId, locks);
    }

    public MonitorIdNode removeLock() {
        try {
            return locks.monitorId;
        } finally {
            locks = locks.next;
        }
    }

    public LockState getLocks() {
        return locks;
    }

    public boolean hasLocks() {
        return locks != null;
    }

    public boolean locksEqual(ObjectState other) {
        LockState a = locks;
        LockState b = other.locks;
        while (a != null && b != null && a.monitorId == b.monitorId) {
            a = a.next;
            b = b.next;
        }
        return a == null && b == null;
    }

    public void setEnsureVirtualized(boolean ensureVirtualized) {
        this.ensureVirtualized = ensureVirtualized;
    }

    public boolean getEnsureVirtualized() {
        return ensureVirtualized;
    }

    @Override
    public String toString() {
        StringBuilder str = new StringBuilder().append('{');
        if (locks != null) {
            str.append('l').append(locks).append(' ');
        }
        if (entries != null) {
            for (int i = 0; i < entries.length; i++) {
                str.append("entry").append(i).append('=').append(entries[i]).append(' ');
            }
        }
        if (materializedValue != null) {
            str.append("mat=").append(materializedValue);
        }

        return str.append('}').toString();
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + Arrays.hashCode(entries);
        result = prime * result + (locks != null ? locks.monitorId.getLockDepth() : 0);
        result = prime * result + ((materializedValue == null) ? 0 : materializedValue.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        ObjectState other = (ObjectState) obj;
        if (!Arrays.equals(entries, other.entries)) {
            return false;
        }
        if (!locksEqual(other)) {
            return false;
        }
        if (materializedValue == null) {
            if (other.materializedValue != null) {
                return false;
            }
        } else if (!materializedValue.equals(other.materializedValue)) {
            return false;
        }
        return true;
    }

    public ObjectState share() {
        copyOnWrite = true;
        return this;
    }
}