/*
 * Copyright (c) 2014, 2017, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.svm.core.graal.nodes;

import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.nodes.spi.Canonicalizable;
import org.graalvm.compiler.nodes.spi.CanonicalizerTool;
import org.graalvm.compiler.nodeinfo.NodeCycles;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodeinfo.NodeSize;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.calc.FloatingNode;
import org.graalvm.compiler.nodes.spi.LIRLowerable;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

import jdk.vm.ci.meta.AllocatableValue;
import jdk.vm.ci.meta.Value;
import jdk.vm.ci.meta.ValueKind;

/**
 * Cast between Word and Object that is floating. This is highly unsafe, because the scheduler can
 * place this node anywhere. The input must therefore be a non-movable object, e.g., an object on
 * the native image heap.
 */
@NodeInfo(cycles = NodeCycles.CYCLES_1, size = NodeSize.SIZE_1)
public final class FloatingWordCastNode extends FloatingNode implements LIRLowerable, Canonicalizable {
    public static final NodeClass<FloatingWordCastNode> TYPE = NodeClass.create(FloatingWordCastNode.class);

    @Input protected ValueNode input;

    public FloatingWordCastNode(Stamp stamp, ValueNode input) {
        super(TYPE, stamp);
        this.input = input;
    }

    @Override
    public Node canonical(CanonicalizerTool tool) {
        if (hasNoUsages()) {
            /* If the cast is unused, it can be eliminated. */
            return input;
        }
        return this;
    }

    @Override
    public void generate(NodeLIRBuilderTool generator) {
        Value value = generator.operand(input);
        ValueKind<?> kind = generator.getLIRGeneratorTool().getLIRKind(stamp(NodeView.DEFAULT));
        assert kind.getPlatformKind().getSizeInBytes() == value.getPlatformKind().getSizeInBytes();

        if (kind.equals(value.getValueKind())) {
            generator.setResult(this, value);
        } else {
            AllocatableValue result = generator.getLIRGeneratorTool().newVariable(kind);
            generator.getLIRGeneratorTool().emitMove(result, value);
            generator.setResult(this, result);
        }
    }
}
