/*
 * Copyright (c) 2011, 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 com.oracle.graal.nodes.extended;

import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.spi.*;
import com.oracle.graal.nodes.type.*;

/**
 * An analog to {@link WriteNode} with the additional semantics of null-checking the receiver object
 * before writing to it.
 */
public class SafeWriteNode extends SafeAccessNode implements StateSplit, Lowerable {

    @Input private ValueNode value;
    @Input(notDataflow = true) private FrameState stateAfter;

    public FrameState stateAfter() {
        return stateAfter;
    }

    public void setStateAfter(FrameState x) {
        assert x == null || x.isAlive() : "frame state must be in a graph";
        updateUsages(stateAfter, x);
        stateAfter = x;
    }

    public boolean hasSideEffect() {
        return true;
    }

    public SafeWriteNode(ValueNode object, ValueNode value, LocationNode location, long leafGraphId) {
        super(object, location, StampFactory.forVoid(), leafGraphId);
        this.value = value;
    }

    public ValueNode value() {
        return value;
    }

    @Override
    public void lower(LoweringTool tool) {
        StructuredGraph graph = (StructuredGraph) graph();
        ValueNode guard = tool.createNullCheckGuard(object(), leafGraphId());
        WriteNode write = graph.add(new WriteNode(object(), value(), location()));
        write.dependencies().add(guard);
        graph.replaceFixedWithFixed(this, write);
    }
}