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package org.graalvm.compiler.nodes;

import org.graalvm.compiler.nodes.spi.NodeWithState;

/**
 * Interface implemented by nodes which may need {@linkplain FrameState deoptimization information}.
 * <p>
 * Sub-interfaces are used to specify exactly when the deoptimization can take place:
 * {@linkplain DeoptBefore before}, {@linkplain DeoptAfter after}, and/or {@linkplain DeoptDuring
 * during}. <br>
 * Note that these sub-interfaces are not mutually exclusive so that nodes that may deoptimize at
 * multiple times can be modeled.
 */
public interface DeoptimizingNode extends NodeWithState {

    /**
     * Determines if this node needs deoptimization information.
     */
    boolean canDeoptimize();

    /**
     * Determines if this node must have a deoptimization FrameState where
     * {@link FrameState#isValidForDeoptimization()} is true.
     */
    default boolean validateDeoptFrameStates() {
        return true;
    }

    /**
     * Interface for nodes that need a {@link FrameState} for deoptimizing to a point before their
     * execution.
     */
    interface DeoptBefore extends DeoptimizingNode {

        /**
         * Sets the {@link FrameState} describing the program state before the execution of this
         * node.
         */
        void setStateBefore(FrameState state);

        FrameState stateBefore();

        default boolean canUseAsStateDuring() {
            return false;
        }
    }

    /**
     * Interface for nodes that need a {@link FrameState} for deoptimizing to a point after their
     * execution.
     */
    interface DeoptAfter extends DeoptimizingNode, StateSplit {
    }

    /**
     * Interface for nodes that need a special {@link FrameState} for deoptimizing during their
     * execution (e.g. {@link Invoke}).
     */
    interface DeoptDuring extends DeoptimizingNode, StateSplit {

        FrameState stateDuring();

        /**
         * Sets the {@link FrameState} describing the program state during the execution of this
         * node.
         */
        void setStateDuring(FrameState state);

        /**
         * Compute the {@link FrameState} describing the program state during the execution of this
         * node from an input {@link FrameState} describing the program state after finishing the
         * execution of this node.
         */
        void computeStateDuring(FrameState stateAfter);
    }
}
