--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/call/SLDispatchNode.java	Tue Apr 14 15:16:14 2015 +0200
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2013, 2015, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.sl.nodes.call;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.dsl.*;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.sl.runtime.*;
+
+public abstract class SLDispatchNode extends Node {
+
+    protected static final int INLINE_CACHE_SIZE = 2;
+
+    public abstract Object executeDispatch(VirtualFrame frame, SLFunction function, Object[] arguments);
+
+    /**
+     * Inline cached specialization of the dispatch.
+     *
+     * <p>
+     * Since SL is a quite simple language, the benefit of the inline cache is quite small: after
+     * checking that the actual function to be executed is the same as the cachedFuntion, we can
+     * safely execute the cached call target. You can reasonably argue that caching the call target
+     * is overkill, since we could just retrieve it via {@code function.getCallTarget()}. However,
+     * in a more complex language the lookup of the call target is usually much more complicated
+     * than in SL. In addition, caching the call target allows method inlining.
+     * </p>
+     *
+     * <p>
+     * {@code limit = "INLINE_CACHE_SIZE"} Specifies the limit number of inline cache specialization
+     * instantiations.
+     * </p>
+     * <p>
+     * {@code guards = "function == cachedFunction"} The inline cache check. Note that
+     * cachedFunction is a final field so that the compiler can optimize the check.
+     * </p>
+     * <p>
+     * {@code assumptions = "cachedFunction.getCallTargetStable()"} Support for function
+     * redefinition: When a function is redefined, the call target maintained by the SLFunction
+     * object is change. To avoid a check for that, we use an Assumption that is invalidated by the
+     * SLFunction when the change is performed. Since checking an assumption is a no-op in compiled
+     * code, the assumption check performed by the DSL does not add any overhead during optimized
+     * execution.
+     * </p>
+     *
+     * @see Cached
+     * @see Specialization
+     *
+     * @param function the dynamically provided function
+     * @param cachedFunction the cached function of the specialization instance
+     * @param callNode the {@link DirectCallNode} specifically created for the {@link CallTarget} in
+     *            cachedFunction.
+     */
+    @Specialization(limit = "INLINE_CACHE_SIZE", guards = "function == cachedFunction", assumptions = "cachedFunction.getCallTargetStable()")
+    protected static Object doDirect(VirtualFrame frame, SLFunction function, Object[] arguments, //
+                    @Cached("function") SLFunction cachedFunction, //
+                    @Cached("create(cachedFunction.getCallTarget())") DirectCallNode callNode) {
+        /* Inline cache hit, we are safe to execute the cached call target. */
+        return callNode.call(frame, arguments);
+    }
+
+    /**
+     * Slow-path code for a call, used when the polymorphic inline cache exceeded its maximum size
+     * specified in <code>INLINE_CACHE_SIZE</code>. Such calls are not optimized any further, e.g.,
+     * no method inlining is performed.
+     */
+    @Specialization(contains = "doDirect")
+    protected static Object doIndirect(VirtualFrame frame, SLFunction function, Object[] arguments, //
+                    @Cached("create()") IndirectCallNode callNode) {
+        /*
+         * SL has a quite simple call lookup: just ask the function for the current call target, and
+         * call it.
+         */
+        return callNode.call(frame, function.getCallTarget(), arguments);
+    }
+
+}