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 *

 * This code is free software; you can redistribute it and/or modify it

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 * 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.nodes.extended;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;

import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;

import org.graalvm.compiler.core.common.type.Stamp;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.spi.Canonicalizable;

import org.graalvm.compiler.graph.spi.CanonicalizerTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.FixedWithNextNode;

import org.graalvm.compiler.nodes.NamedLocationIdentity;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.type.StampTool;

import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.meta.Assumptions;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.ResolvedJavaField;

import jdk.vm.ci.meta.ResolvedJavaType;

@NodeInfo(cycles = CYCLES_2, size = SIZE_1)

public abstract class UnsafeAccessNode extends FixedWithNextNode implements Canonicalizable {

    public static final NodeClass<UnsafeAccessNode> TYPE = NodeClass.create(UnsafeAccessNode.class);

    @Input ValueNode object;

    @Input ValueNode offset;

    protected final JavaKind accessKind;

    protected final LocationIdentity locationIdentity;

    protected final boolean forceAnyLocation;

    protected UnsafeAccessNode(NodeClass<? extends UnsafeAccessNode> c, Stamp stamp, ValueNode object, ValueNode offset, JavaKind accessKind, LocationIdentity locationIdentity,

                    boolean forceAnyLocation) {

        super(c, stamp);

        this.forceAnyLocation = forceAnyLocation;

        assert accessKind != null;

        assert locationIdentity != null;

        this.object = object;

        this.offset = offset;

        this.accessKind = accessKind;

        this.locationIdentity = locationIdentity;

    }

    public LocationIdentity getLocationIdentity() {

        return locationIdentity;

    }

    public boolean isAnyLocationForced() {

        return forceAnyLocation;

    }

    public ValueNode object() {

        return object;

    }

    public ValueNode offset() {

        return offset;

    }

    public JavaKind accessKind() {

        return accessKind;

    }

    @Override

    public Node canonical(CanonicalizerTool tool) {

        if (!isAnyLocationForced() && getLocationIdentity().isAny()) {

            if (offset().isConstant()) {

                long constantOffset = offset().asJavaConstant().asLong();

                // Try to canonicalize to a field access.

                ResolvedJavaType receiverType = StampTool.typeOrNull(object());

                if (receiverType != null) {

                    if (field != null && field.getJavaKind() == this.accessKind()) {

                        assert !graph().isAfterFloatingReadPhase() : "cannot add more precise memory location after floating read phase";

                        // Unsafe accesses never have volatile semantics.

                        // Memory barriers are placed around such an unsafe access at construction

                        // time if necessary, unlike AccessFieldNodes which encapsulate their

                        // potential volatile semantics.

                        return cloneAsFieldAccess(graph().getAssumptions(), field, false);

                    }

                }

            }

            ResolvedJavaType receiverType = StampTool.typeOrNull(object());

            // Try to build a better location identity.

            if (receiverType != null && receiverType.isArray()) {

                LocationIdentity identity = NamedLocationIdentity.getArrayLocation(receiverType.getComponentType().getJavaKind());

                assert !graph().isAfterFloatingReadPhase() : "cannot add more precise memory location after floating read phase";

                return cloneAsArrayAccess(offset(), identity);

            }

        }

        return this;

    }

    protected ValueNode cloneAsFieldAccess(Assumptions assumptions, ResolvedJavaField field) {

        return cloneAsFieldAccess(assumptions, field, field.isVolatile());

    }

    protected abstract ValueNode cloneAsFieldAccess(Assumptions assumptions, ResolvedJavaField field, boolean volatileAccess);

    protected abstract ValueNode cloneAsArrayAccess(ValueNode location, LocationIdentity identity);

}