changeset 15450:be0c151d912b

Truffle/Instrumentation: API revisions
author Michael Van De Vanter <michael.van.de.vanter@oracle.com>
date Tue, 29 Apr 2014 12:05:58 -0700
parents 041156bb59b2
children 3774b6f4319b
files graal/com.oracle.truffle.api/src/com/oracle/truffle/api/ExecutionContext.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/impl/AbstractExecutionContext.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Instrument.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Visualizer.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/DefaultInstrument.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/DefaultVisualizer.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationImpl.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationNode.java graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationNodeImpl.java
diffstat 9 files changed, 610 insertions(+), 550 deletions(-) [+]
line wrap: on
line diff
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/ExecutionContext.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/ExecutionContext.java	Tue Apr 29 12:05:58 2014 -0700
@@ -49,12 +49,12 @@
     /**
      * Gets access to AST instrumentation services.
      */
-    Instrumentation instrumentation();
+    Instrumentation getInstrumentation();
 
     /**
      * Access to information visualization services for the specific language.
      */
-    Visualizer visualizer();
+    Visualizer getVisualizer();
 
     /**
      * Add instrumentation to subsequently constructed Truffle ASTs for the guest language; every
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/impl/AbstractExecutionContext.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/impl/AbstractExecutionContext.java	Tue Apr 29 12:05:58 2014 -0700
@@ -44,11 +44,11 @@
         return sourceManager;
     }
 
-    public final Instrumentation instrumentation() {
+    public final Instrumentation getInstrumentation() {
         return instrumentation;
     }
 
-    public Visualizer visualizer() {
+    public Visualizer getVisualizer() {
         return visualizer;
     }
 
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Instrument.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Instrument.java	Tue Apr 29 12:05:58 2014 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -24,17 +24,103 @@
  */
 package com.oracle.truffle.api.instrument;
 
+import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
+import com.oracle.truffle.api.CompilerDirectives.SlowPath;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.impl.*;
+import com.oracle.truffle.api.nodes.*;
+
 /**
  * A receiver of Truffle AST {@link ExecutionEvents}, propagated from a {@link Probe} to which the
- * instrument is attached.
+ * instrument is attached, for the benefit of associated <em>tools</em>.
  * <p>
- * <strong>Disclaimer:</strong> experimental interface under development.
+ * Guidelines for implementing Instruments, with particular attention to avoiding undesired runtime
+ * performance overhead:
+ * <ol>
+ * <li>Extend {@link Instrument} and override only the event handling methods for which some action
+ * is needed.</li>
+ * <li>Instruments are Truffle {@link Node}s and should be coded as much as possible in the desired
+ * <em>Truffle style</em>, documented more thoroughly elsewhere.</li>
+ * <li>Maintain as little state as possible.</li>
+ * <li>If state is necessary, make it {@code final} if possible.</li>
+ * <li>If non-final state is necessary, annotate it as {@link CompilationFinal} and call
+ * {@linkplain InstrumentationNode#notifyProbeChanged(Instrument)} whenever it is modified.</li>
+ * <li>Never store a {@link Frame} value in a field.</li>
+ * <li>Minimize computation in standard execution paths.</li>
+ * <li>Callbacks to tools should be made via callbacks provided at construction and stored in
+ * {@code final} fields.</li>
+ * <li>Tool callback methods should usually be annotated as {@link SlowPath} to prevent them from
+ * being inlined into fast execution paths.</li>
+ * <li>If computation is needed, and if performance is important, then the computation is best
+ * expressed as a guest language AST and evaluated using standard Truffle mechanisms so that
+ * standard Truffle optimizations can be applied.</li>
+ * </ol>
+ * <p>
+ * Guidelines for attachment to a {@link Probe}:
+ * <ol>
+ * <li>An Instrument instance must only attached to a single {@link Probe}, each of which is
+ * associated uniquely with a specific syntactic unit of a guest language program, and thus
+ * (initially) to a specific {@linkplain Node Truffle AST node}.</li>
+ * <li>When the AST containing such a node is copied at runtime, the {@link Probe} will be shared by
+ * every copy, and so the Instrument will receive events corresponding to the intended syntactic
+ * unit of code, independent of which AST copy is being executed.</li>
+ * </ol>
+ *
+ * <p>
+ * <strong>Disclaimer:</strong> experimental; under development.
+ *
+ * @see Instrumentation
+ * @see Probe
+ * @see Instrument
+ * @see ASTNodeProber
  */
-public interface Instrument extends ExecutionEvents {
+public class Instrument extends InstrumentationNode {
+
+    protected Instrument() {
+    }
+
+    public void enter(Node astNode, VirtualFrame frame) {
+    }
+
+    public void leave(Node astNode, VirtualFrame frame) {
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, boolean result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, byte result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, short result) {
+        leave(astNode, frame, (Object) result);
+    }
 
-    /**
-     * @return the {@link Probe} to which this instrument is attached.
-     */
-    Probe getProbe();
+    public void leave(Node astNode, VirtualFrame frame, int result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, long result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, char result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, float result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, double result) {
+        leave(astNode, frame, (Object) result);
+    }
+
+    public void leave(Node astNode, VirtualFrame frame, Object result) {
+    }
+
+    public void leaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
+    }
 
 }
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Visualizer.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Visualizer.java	Tue Apr 29 12:05:58 2014 -0700
@@ -24,10 +24,18 @@
  */
 package com.oracle.truffle.api.instrument;
 
+import com.oracle.truffle.api.*;
 import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.nodes.*;
 
 /**
- * Visualization services for guest language and Truffle information.
+ * Visualization services for the benefit of {@link Instrumentation}-based tools, possibly
+ * specialized for each guest language and possibly specialized for relevant information from the
+ * underlying Truffle implementation.
+ * <p>
+ * <strong>Disclaimer:</strong> experimental interface under development.
+ *
+ * @See Instrumentation
  */
 public interface Visualizer {
 
@@ -38,6 +46,21 @@
     ASTPrinter getASTPrinter();
 
     /**
+     * A short description of a source location in terms of source + line number.
+     */
+    String displaySourceLocation(Node node);
+
+    /**
+     * Describes the name of the method containing a node.
+     */
+    String displayMethodName(Node node);
+
+    /**
+     * The name of the method.
+     */
+    String displayCallTargetName(CallTarget callTarget);
+
+    /**
      * Converts a value in the guest language to a display string.
      */
     String displayValue(Object value);
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/DefaultInstrument.java	Tue Apr 22 18:32:08 2014 -0700
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,84 +0,0 @@
-/*
- * 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.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * 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.api.instrument.impl;
-
-import com.oracle.truffle.api.frame.*;
-import com.oracle.truffle.api.instrument.*;
-import com.oracle.truffle.api.nodes.*;
-
-/**
- * An {@link Instrument} that implements all {@link ExecutionEvents} notifications with empty
- * methods.
- */
-public class DefaultInstrument extends InstrumentationNodeImpl implements Instrument {
-
-    protected DefaultInstrument() {
-    }
-
-    public void enter(Node astNode, VirtualFrame frame) {
-    }
-
-    public void leave(Node astNode, VirtualFrame frame) {
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, boolean result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, byte result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, short result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, int result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, long result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, char result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, float result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, double result) {
-        leave(astNode, frame, (Object) result);
-    }
-
-    public void leave(Node astNode, VirtualFrame frame, Object result) {
-    }
-
-    public void leaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
-    }
-
-}
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/DefaultVisualizer.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/DefaultVisualizer.java	Tue Apr 29 12:05:58 2014 -0700
@@ -24,8 +24,12 @@
  */
 package com.oracle.truffle.api.instrument.impl;
 
+import java.io.*;
+
+import com.oracle.truffle.api.*;
 import com.oracle.truffle.api.frame.*;
 import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.nodes.*;
 
 public class DefaultVisualizer implements Visualizer {
 
@@ -39,6 +43,43 @@
         return astPrinter;
     }
 
+    public String displaySourceLocation(Node node) {
+        if (node == null) {
+            return "<unknown>";
+        }
+        SourceSection section = node.getSourceSection();
+        boolean estimated = false;
+        if (section == null) {
+            section = node.getEncapsulatingSourceSection();
+            estimated = true;
+        }
+
+        String sourceString;
+        if (section == null || section.getSource() == null) {
+            sourceString = "<unknown source>";
+        } else {
+            String sourceName = new File(section.getSource().getName()).getName();
+            int startLine = section.getStartLine();
+            sourceString = String.format("%s:%d%s", sourceName, startLine, estimated ? "~" : "");
+        }
+        return sourceString;
+    }
+
+    public String displayMethodName(Node node) {
+        if (node == null) {
+            return null;
+        }
+        RootNode root = node.getRootNode();
+        if (root == null) {
+            return "unknown";
+        }
+        return root.getCallTarget().toString();
+    }
+
+    public String displayCallTargetName(CallTarget callTarget) {
+        return callTarget.toString();
+    }
+
     public String displayValue(Object value) {
         return value.toString();
     }
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationImpl.java	Tue Apr 22 18:32:08 2014 -0700
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationImpl.java	Tue Apr 29 12:05:58 2014 -0700
@@ -30,10 +30,6 @@
 import com.oracle.truffle.api.instrument.*;
 import com.oracle.truffle.api.source.*;
 
-/**
- * @author mlvdv
- *
- */
 public final class InstrumentationImpl implements Instrumentation {
 
     private final ExecutionContext context;
@@ -80,7 +76,7 @@
         if (probe != null) {
             return probe;
         }
-        probe = InstrumentationNodeImpl.createProbe(this, sourceSection, eventListener);
+        probe = InstrumentationNode.createProbe(this, sourceSection, eventListener);
 
         // Register new probe by unique SourceSection
         srcToProbe.put(sourceSection, probe);
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationNode.java	Tue Apr 29 12:05:58 2014 -0700
@@ -0,0 +1,446 @@
+/*
+ * 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.api.instrument.impl;
+
+import java.util.*;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * Abstract implementation of Truffle {@link Node} to be used for AST probes and instruments.
+ * <p>
+ * Coordinates propagation of Truffle AST {@link ExecutionEvents}.
+ */
+public abstract class InstrumentationNode extends Node implements ExecutionEvents {
+
+    // TODO (mlvdv) This is a pretty awkward design; it is a priority to revise it.
+
+    /**
+     * Creates a new {@link Probe}, presumed to be unique to a particular {@linkplain SourceSection}
+     * extent of guest language source code.
+     *
+     * @param eventListener an optional listener for certain instrumentation-related events.
+     * @return a new probe
+     */
+    static Probe createProbe(InstrumentationImpl instrumentation, SourceSection sourceSection, InstrumentEventListener eventListener) {
+        return new ProbeImpl(instrumentation, sourceSection, eventListener);
+    }
+
+    /**
+     * Next in chain.
+     */
+    @Child protected InstrumentationNode next;
+
+    protected InstrumentationNode() {
+    }
+
+    /**
+     * @return the instance of {@link Probe} to which this instrument is attached.
+     */
+    public Probe getProbe() {
+        final InstrumentationNode parent = (InstrumentationNode) getParent();
+        return parent == null ? null : parent.getProbe();
+    }
+
+    /**
+     * Add a probe to the end of this probe chain.
+     */
+    private void internalAddInstrument(Instrument newInstrument) {
+        if (next == null) {
+            this.next = insert(newInstrument);
+        } else {
+            next.internalAddInstrument(newInstrument);
+        }
+    }
+
+    private void internalRemoveInstrument(Instrument oldInstrument) {
+        if (next == null) {
+            throw new RuntimeException("Couldn't find probe to remove: " + oldInstrument);
+        } else if (next == oldInstrument) {
+            if (oldInstrument.next == null) {
+                this.next = null;
+            } else {
+                this.next = insert(oldInstrument.next);
+                oldInstrument.next = null;
+            }
+        } else {
+            next.internalRemoveInstrument(oldInstrument);
+        }
+    }
+
+    /**
+     * Reports to the instance of {@link Probe} holding this instrument that some essential state
+     * has changed that requires deoptimization.
+     */
+    @CompilerDirectives.SlowPath
+    protected void notifyProbeChanged(Instrument instrument) {
+        final ProbeImpl probe = (ProbeImpl) getProbe();
+        probe.notifyProbeChanged(instrument);
+    }
+
+    private void internalEnter(Node astNode, VirtualFrame frame) {
+        enter(astNode, frame);
+        if (next != null) {
+            next.internalEnter(astNode, frame);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame) {
+        leave(astNode, frame);
+        if (next != null) {
+            next.internalLeave(astNode, frame);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, boolean result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, byte result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, short result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, int result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, long result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, char result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, float result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, double result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeave(Node astNode, VirtualFrame frame, Object result) {
+        leave(astNode, frame, result);
+        if (next != null) {
+            next.internalLeave(astNode, frame, result);
+        }
+    }
+
+    private void internalLeaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
+        leaveExceptional(astNode, frame, null);
+        if (next != null) {
+            next.internalLeaveExceptional(astNode, frame, e);
+        }
+    }
+
+    /**
+     * Holder of a chain of {@linkplain InstrumentationNode instruments}: manages the
+     * {@link Assumption} that none of the instruments have changed since last checked.
+     * <p>
+     * An instance is intended to be shared by every clone of the AST node with which it is
+     * originally attached, so it holds no parent pointer.
+     * <p>
+     * May be categorized by one or more {@linkplain PhylumTag tags}, signifying information useful
+     * for instrumentation about its AST location(s).
+     */
+    private static final class ProbeImpl extends InstrumentationNode implements Probe {
+
+        final InstrumentationImpl instrumentation;
+
+        final InstrumentEventListener eventListener;
+
+        @CompilerDirectives.CompilationFinal private Assumption probeUnchanged;
+
+        /**
+         * When in stepping mode, ordinary line breakpoints are ignored, but every entry at a line
+         * will cause a halt.
+         */
+        @CompilerDirectives.CompilationFinal private boolean stepping;
+
+        /**
+         * Source information about the AST node to which this instrumentation is attached.
+         */
+        private final SourceSection probedSourceSection;
+
+        private final Set<PhylumTag> tags = EnumSet.noneOf(PhylumTag.class);
+
+        private ProbeImpl(InstrumentationImpl instrumentation, SourceSection sourceSection, InstrumentEventListener eventListener) {
+            this.instrumentation = instrumentation;
+            this.probedSourceSection = sourceSection;
+            this.eventListener = eventListener == null ? NullInstrumentEventListener.INSTANCE : eventListener;
+            this.probeUnchanged = Truffle.getRuntime().createAssumption();
+            this.next = null;
+        }
+
+        @Override
+        public Probe getProbe() {
+            return this;
+        }
+
+        @Override
+        protected void notifyProbeChanged(Instrument instrument) {
+            probeUnchanged.invalidate();
+            probeUnchanged = Truffle.getRuntime().createAssumption();
+        }
+
+        public SourceSection getSourceLocation() {
+            return probedSourceSection;
+        }
+
+        public void tagAs(PhylumTag tag) {
+            assert tag != null;
+            if (!tags.contains(tag)) {
+                tags.add(tag);
+                instrumentation.newTagAdded(this, tag);
+            }
+        }
+
+        public boolean isTaggedAs(PhylumTag tag) {
+            assert tag != null;
+            return tags.contains(tag);
+        }
+
+        public Set<PhylumTag> getPhylumTags() {
+            return tags;
+        }
+
+        public void setStepping(boolean stepping) {
+            if (this.stepping != stepping) {
+                this.stepping = stepping;
+                probeUnchanged.invalidate();
+                probeUnchanged = Truffle.getRuntime().createAssumption();
+            }
+        }
+
+        public boolean isStepping() {
+            return stepping;
+        }
+
+        @CompilerDirectives.SlowPath
+        public void addInstrument(Instrument instrument) {
+            probeUnchanged.invalidate();
+            super.internalAddInstrument(instrument);
+            probeUnchanged = Truffle.getRuntime().createAssumption();
+        }
+
+        @CompilerDirectives.SlowPath
+        public void removeInstrument(Instrument instrument) {
+            probeUnchanged.invalidate();
+            super.internalRemoveInstrument(instrument);
+            probeUnchanged = Truffle.getRuntime().createAssumption();
+        }
+
+        public void notifyEnter(Node astNode, VirtualFrame frame) {
+            if (stepping || next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                if (stepping) {
+                    eventListener.haltedAt(astNode, frame.materialize());
+                }
+                if (next != null) {
+                    next.internalEnter(astNode, frame);
+                }
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, boolean result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, byte result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, short result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, int result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, long result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, char result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, float result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, double result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeave(Node astNode, VirtualFrame frame, Object result) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeave(astNode, frame, result);
+            }
+        }
+
+        public void notifyLeaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
+            if (next != null) {
+                if (!probeUnchanged.isValid()) {
+                    CompilerDirectives.transferToInterpreter();
+                }
+                next.internalLeaveExceptional(astNode, frame, e);
+            }
+        }
+
+        public void enter(Node astNode, VirtualFrame frame) {
+        }
+
+        public void leave(Node astNode, VirtualFrame frame) {
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, boolean result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, byte result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, short result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, int result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, long result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, char result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, float result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, double result) {
+            leave(astNode, frame, (Object) result);
+        }
+
+        public void leave(Node astNode, VirtualFrame frame, Object result) {
+        }
+
+        public void leaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
+        }
+
+    }
+
+}
--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/InstrumentationNodeImpl.java	Tue Apr 22 18:32:08 2014 -0700
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,448 +0,0 @@
-/*
- * 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.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * 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.api.instrument.impl;
-
-import java.util.*;
-
-import com.oracle.truffle.api.*;
-import com.oracle.truffle.api.frame.*;
-import com.oracle.truffle.api.instrument.*;
-import com.oracle.truffle.api.nodes.*;
-
-/**
- * Abstract implementation of Truffle {@link Node} to be used for AST probes and instruments.
- * <p>
- * Coordinates propagation of Truffle AST {@link ExecutionEvents}.
- */
-public abstract class InstrumentationNodeImpl extends Node implements ExecutionEvents {
-
-    // TODO (mlvdv) This is a pretty awkward design.
-
-    /**
-     * Creates a new {@link Probe}, presumed to be unique to a particular {@linkplain SourceSection}
-     * extent of guest language source code.
-     *
-     * @param eventListener an optional listener for certain instrumentation-related events.
-     * @return a new probe
-     */
-    static Probe createProbe(InstrumentationImpl instrumentation, SourceSection sourceSection, InstrumentEventListener eventListener) {
-        return new ProbeImpl(instrumentation, sourceSection, eventListener);
-    }
-
-    /**
-     * Next in chain.
-     */
-    @Child protected InstrumentationNodeImpl next;
-
-    protected InstrumentationNodeImpl() {
-    }
-
-    /**
-     * @return the instance of {@link Probe} to which this instrument is attached.
-     */
-    public Probe getProbe() {
-        final InstrumentationNodeImpl parent = (InstrumentationNodeImpl) getParent();
-        return parent == null ? null : parent.getProbe();
-    }
-
-    /**
-     * Add a probe to the end of this probe chain.
-     */
-    void internalAddInstrument(InstrumentationNodeImpl newInstrument) {
-        if (next == null) {
-            this.next = insert(newInstrument);
-        } else {
-            next.internalAddInstrument(newInstrument);
-        }
-    }
-
-    void internalRemoveInstrument(InstrumentationNodeImpl oldInstrument) {
-        if (next == null) {
-            throw new RuntimeException("Couldn't find probe to remove: " + oldInstrument);
-        } else if (next == oldInstrument) {
-            if (oldInstrument.next == null) {
-                this.next = null;
-            } else {
-                this.next = insert(oldInstrument.next);
-                oldInstrument.next = null;
-            }
-        } else {
-            next.internalRemoveInstrument(oldInstrument);
-        }
-    }
-
-    /**
-     * Reports to the instance of {@link Probe} holding this instrument that some essential state
-     * has changed that requires deoptimization.
-     */
-    @CompilerDirectives.SlowPath
-    protected void notifyProbeChanged(InstrumentationNodeImpl instrument) {
-        final ProbeImpl probe = (ProbeImpl) getProbe();
-        probe.notifyProbeChanged(instrument);
-    }
-
-    private void internalEnter(Node astNode, VirtualFrame frame) {
-        enter(astNode, frame);
-        if (next != null) {
-            next.internalEnter(astNode, frame);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame) {
-        leave(astNode, frame);
-        if (next != null) {
-            next.internalLeave(astNode, frame);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, boolean result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, byte result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, short result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, int result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, long result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, char result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, float result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, double result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeave(Node astNode, VirtualFrame frame, Object result) {
-        leave(astNode, frame, result);
-        if (next != null) {
-            next.internalLeave(astNode, frame, result);
-        }
-    }
-
-    private void internalLeaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
-        leaveExceptional(astNode, frame, null);
-        if (next != null) {
-            next.internalLeaveExceptional(astNode, frame, e);
-        }
-    }
-
-    /**
-     * Holder of a chain of {@linkplain InstrumentationNodeImpl instruments}: manages the
-     * {@link Assumption} that none of the instruments have changed since last checked.
-     * <p>
-     * An instance is intended to be shared by every clone of the AST node with which it is
-     * originally attached, so it holds no parent pointer.
-     * <p>
-     * May be categorized by one or more {@linkplain PhylumTag tags}, signifying information useful
-     * for instrumentation about its AST location(s).
-     */
-    private static final class ProbeImpl extends InstrumentationNodeImpl implements Probe {
-
-        final InstrumentationImpl instrumentation;
-
-        final InstrumentEventListener eventListener;
-
-        @CompilerDirectives.CompilationFinal private Assumption probeUnchanged;
-
-        /**
-         * When in stepping mode, ordinary line breakpoints are ignored, but every entry at a line
-         * will cause a halt.
-         */
-        @CompilerDirectives.CompilationFinal private boolean stepping;
-
-        /**
-         * Source information about the AST node to which this instrumentation is attached.
-         */
-        private final SourceSection probedSourceSection;
-
-        private final Set<PhylumTag> tags = EnumSet.noneOf(PhylumTag.class);
-
-        private ProbeImpl(InstrumentationImpl instrumentation, SourceSection sourceSection, InstrumentEventListener eventListener) {
-            this.instrumentation = instrumentation;
-            this.probedSourceSection = sourceSection;
-            this.eventListener = eventListener == null ? NullInstrumentEventListener.INSTANCE : eventListener;
-            this.probeUnchanged = Truffle.getRuntime().createAssumption();
-            this.next = null;
-        }
-
-        @Override
-        public Probe getProbe() {
-            return this;
-        }
-
-        @Override
-        protected void notifyProbeChanged(InstrumentationNodeImpl instrument) {
-            probeUnchanged.invalidate();
-            probeUnchanged = Truffle.getRuntime().createAssumption();
-        }
-
-        public SourceSection getSourceLocation() {
-            return probedSourceSection;
-        }
-
-        public void tagAs(PhylumTag tag) {
-            assert tag != null;
-            if (!tags.contains(tag)) {
-                tags.add(tag);
-                instrumentation.newTagAdded(this, tag);
-            }
-        }
-
-        public boolean isTaggedAs(PhylumTag tag) {
-            assert tag != null;
-            return tags.contains(tag);
-        }
-
-        public Set<PhylumTag> getPhylumTags() {
-            return tags;
-        }
-
-        public void setStepping(boolean stepping) {
-            if (this.stepping != stepping) {
-                this.stepping = stepping;
-                probeUnchanged.invalidate();
-                probeUnchanged = Truffle.getRuntime().createAssumption();
-            }
-        }
-
-        public boolean isStepping() {
-            return stepping;
-        }
-
-        @CompilerDirectives.SlowPath
-        public void addInstrument(Instrument instrument) {
-            probeUnchanged.invalidate();
-            final InstrumentationNodeImpl instrumentImpl = (InstrumentationNodeImpl) instrument;
-            super.internalAddInstrument(instrumentImpl);
-            probeUnchanged = Truffle.getRuntime().createAssumption();
-        }
-
-        @CompilerDirectives.SlowPath
-        public void removeInstrument(Instrument instrument) {
-            probeUnchanged.invalidate();
-            final InstrumentationNodeImpl instrumentImpl = (InstrumentationNodeImpl) instrument;
-            super.internalRemoveInstrument(instrumentImpl);
-            probeUnchanged = Truffle.getRuntime().createAssumption();
-        }
-
-        public void notifyEnter(Node astNode, VirtualFrame frame) {
-            if (stepping || next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                if (stepping) {
-                    eventListener.haltedAt(astNode, frame.materialize());
-                }
-                if (next != null) {
-                    next.internalEnter(astNode, frame);
-                }
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, boolean result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, byte result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, short result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, int result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, long result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, char result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, float result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, double result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeave(Node astNode, VirtualFrame frame, Object result) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeave(astNode, frame, result);
-            }
-        }
-
-        public void notifyLeaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
-            if (next != null) {
-                if (!probeUnchanged.isValid()) {
-                    CompilerDirectives.transferToInterpreter();
-                }
-                next.internalLeaveExceptional(astNode, frame, e);
-            }
-        }
-
-        public void enter(Node astNode, VirtualFrame frame) {
-        }
-
-        public void leave(Node astNode, VirtualFrame frame) {
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, boolean result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, byte result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, short result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, int result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, long result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, char result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, float result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, double result) {
-            leave(astNode, frame, (Object) result);
-        }
-
-        public void leave(Node astNode, VirtualFrame frame, Object result) {
-        }
-
-        public void leaveExceptional(Node astNode, VirtualFrame frame, Exception e) {
-        }
-
-    }
-
-}