/*
 * Copyright (c) 2013, 2014, 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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 */
package com.oracle.truffle.sl.nodes.call;

import com.oracle.truffle.api.frame.*;
import com.oracle.truffle.api.nodes.*;
import com.oracle.truffle.sl.runtime.*;

/**
 * Before a call is executed the first time, the dispatch node is a
 * {@link SLUninitializedDispatchNode}. During execution, the call is optimized using a polymprphic
 * inline cache, i.e., a chain of {@link SLDirectDispatchNode}s. The chain is terminated by a
 * {@link SLUninitializedDispatchNode}. If the chain gets too long (longer than
 * {@link #INLINE_CACHE_SIZE}), i.e., if the call is too polymorphic, the whole chain is replaced by
 * a single {@link SLGenericDispatchNode}. All this rewriting happens on runtime, based on profiling
 * feedback of the actual execution.
 * <p>
 * Example of the chain of nodes ({@code C}: {@link SLCallNode}; {@code U}:
 * {@link SLUninitializedDispatchNode}; {@code D}: {@link SLDirectDispatchNode}; {@code G}:
 * {@link SLGenericDispatchNode}):
 * <ol>
 * <li>After parsing: {@code C->U}
 * <li>After execution of function {@code f1}: {@code C->D(f1)->U}
 * <li>After execution of function {@code f2}: {@code C->D(f1)->D(f2)->U}
 * <li>After execution of function {@code f3}: {@code C->G}
 * </ol>
 * */
public abstract class SLAbstractDispatchNode extends Node {

    protected static final int INLINE_CACHE_SIZE = 2;

    protected abstract Object executeDispatch(VirtualFrame frame, SLFunction function, SLArguments arguments);
}