/*
 * 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
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 * questions.
 */


package org.graalvm.compiler.nodes;

import static org.graalvm.compiler.nodeinfo.InputType.Condition;
import static org.graalvm.compiler.nodeinfo.InputType.Guard;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_2;

import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.graph.IterableNodeType;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.NodeSourcePosition;
import org.graalvm.compiler.graph.spi.Canonicalizable;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodeinfo.Verbosity;
import org.graalvm.compiler.nodes.extended.AnchoringNode;
import org.graalvm.compiler.nodes.extended.GuardingNode;

import jdk.vm.ci.meta.DeoptimizationAction;
import jdk.vm.ci.meta.DeoptimizationReason;
import jdk.vm.ci.meta.SpeculationLog.Speculation;

A guard is a node that deoptimizes based on a conditional expression. Guards are not attached to
a certain frame state, they can move around freely and will always use the correct frame state
when the nodes are scheduled (i.e., the last emitted frame state). The node that is guarded has a
data dependency on the guard and the guard in turn has a data dependency on the condition. A
guard may only be executed if it is guaranteed that the guarded node is executed too (if no
exceptions are thrown). Therefore, an anchor is placed after a control flow split and the guard
has a data dependency to the anchor. The anchor is the most distant node that is post-dominated
by the guarded node and the guard can be scheduled anywhere between those two nodes. This ensures
maximum flexibility for the guard node and guarantees that deoptimization occurs only if the
control flow would have reached the guarded node (without taking exceptions into account).
/**
 * A guard is a node that deoptimizes based on a conditional expression. Guards are not attached to
 * a certain frame state, they can move around freely and will always use the correct frame state
 * when the nodes are scheduled (i.e., the last emitted frame state). The node that is guarded has a
 * data dependency on the guard and the guard in turn has a data dependency on the condition. A
 * guard may only be executed if it is guaranteed that the guarded node is executed too (if no
 * exceptions are thrown). Therefore, an anchor is placed after a control flow split and the guard
 * has a data dependency to the anchor. The anchor is the most distant node that is post-dominated
 * by the guarded node and the guard can be scheduled anywhere between those two nodes. This ensures
 * maximum flexibility for the guard node and guarantees that deoptimization occurs only if the
 * control flow would have reached the guarded node (without taking exceptions into account).
 */
@NodeInfo(nameTemplate = "Guard(!={p#negated}) {p#reason/s}", allowedUsageTypes = {Guard}, size = SIZE_2, cycles = CYCLES_2)
public class GuardNode extends FloatingAnchoredNode implements Canonicalizable, GuardingNode, DeoptimizingGuard, IterableNodeType {

    public static final NodeClass<GuardNode> TYPE = NodeClass.create(GuardNode.class);
    @Input(Condition) protected LogicNode condition;
    protected DeoptimizationReason reason;
    protected DeoptimizationAction action;
    protected Speculation speculation;
    protected boolean negated;
    protected NodeSourcePosition noDeoptSuccessorPosition;

    public GuardNode(LogicNode condition, AnchoringNode anchor, DeoptimizationReason reason, DeoptimizationAction action, boolean negated, Speculation speculation,
                    NodeSourcePosition noDeoptSuccessorPosition) {
        this(TYPE, condition, anchor, reason, action, negated, speculation, noDeoptSuccessorPosition);
    }

    protected GuardNode(NodeClass<? extends GuardNode> c, LogicNode condition, AnchoringNode anchor, DeoptimizationReason reason, DeoptimizationAction action, boolean negated,
                    Speculation speculation, NodeSourcePosition noDeoptSuccessorPosition) {
        super(c, StampFactory.forVoid(), anchor);
        this.condition = condition;
        this.reason = reason;
        this.action = action;
        this.negated = negated;
        this.speculation = speculation;
        this.noDeoptSuccessorPosition = noDeoptSuccessorPosition;
    }

    
The instruction that produces the tested boolean value.
/**
     * The instruction that produces the tested boolean value.
     */
    @Override
    public LogicNode getCondition() {
        return condition;
    }

    @Override
    public void setCondition(LogicNode x, boolean negated) {
        updateUsages(condition, x);
        condition = x;
        this.negated = negated;
    }

    @Override
    public boolean isNegated() {
        return negated;
    }

    @Override
    public DeoptimizationReason getReason() {
        return reason;
    }

    @Override
    public DeoptimizationAction getAction() {
        return action;
    }

    @Override
    public Speculation getSpeculation() {
        return speculation;
    }

    public void setSpeculation(Speculation speculation) {
        this.speculation = speculation;
    }

    @Override
    public String toString(Verbosity verbosity) {
        if (verbosity == Verbosity.Name && negated) {
            return "!" + super.toString(verbosity);
        } else {
            return super.toString(verbosity);
        }
    }

    @Override
    public Node canonical(CanonicalizerTool tool) {
        if (getCondition() instanceof LogicNegationNode) {
            LogicNegationNode negation = (LogicNegationNode) getCondition();
            return new GuardNode(negation.getValue(), getAnchor(), reason, action, !negated, speculation, noDeoptSuccessorPosition);
        }
        if (getCondition() instanceof LogicConstantNode) {
            LogicConstantNode c = (LogicConstantNode) getCondition();
            if (c.getValue() != negated) {
                return null;
            }
        }
        return this;
    }

    public FixedWithNextNode lowerGuard() {
        return null;
    }

    public void negate() {
        negated = !negated;
    }

    @Override
    public void setAction(DeoptimizationAction invalidaterecompile) {
        this.action = invalidaterecompile;
    }

    @Override
    public void setReason(DeoptimizationReason reason) {
        this.reason = reason;
    }

    @Override
    public NodeSourcePosition getNoDeoptSuccessorPosition() {
        return noDeoptSuccessorPosition;
    }

    @Override
    public void setNoDeoptSuccessorPosition(NodeSourcePosition noDeoptSuccessorPosition) {
        this.noDeoptSuccessorPosition = noDeoptSuccessorPosition;
    }
}