--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/TruffleTool.java	Tue Jan 27 20:26:41 2015 -0800
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 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.  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;
+
+/**
+ * {@linkplain Instrument Instrumentation}-based tools that gather data during Guest Language
+ * program execution.
+ * <p>
+ * Tools share a common <em>life cycle</em>:
+ * <ul>
+ * <li>A newly created tool is inert until {@linkplain #install() installed}.</li>
+ * <li>An installed tool becomes <em>enabled</em> and immediately begins installing
+ * {@linkplain Instrument instrumentation} on subsequently created ASTs and collecting data from
+ * those instruments</li>
+ * <li>A tool may only be installed once.</li>
+ * <li>It should be possible to install multiple instances of a tool, possibly (but not necessarily)
+ * configured differently with respect to what data is being collected.</li>
+ * <li>Once installed, a tool can be {@linkplain #setEnabled(boolean) enabled and disabled}
+ * arbitrarily.</li>
+ * <li>A disabled tool:
+ * <ul>
+ * <li>Collects no data;</li>
+ * <li>Retains existing AST instrumentation;</li>
+ * <li>Continues to instrument newly created ASTs; and</li>
+ * <li>Retains previously collected data.</li>
+ * </ul>
+ * </li>
+ * <li>An installed tool may be {@linkplain #reset() reset} at any time, which leaves the tool
+ * installed but with all previously collected data removed.</li>
+ * <li>A {@linkplain #dispose() disposed} tool removes all instrumentation (but not
+ * {@linkplain Probe probes}) and becomes permanently disabled; previously collected data persists.</li>
+ * </ul>
+ * <p>
+ * Tool-specific methods that access data collected by the tool should:
+ * <ul>
+ * <li>Return modification-safe representations of the data; and</li>
+ * <li>Not change the state of the data.</li>
+ * </ul>
+ * <b>Note:</b><br>
+ * Tool installation is currently <em>global</em> to the Truffle Execution environment. When
+ * language-agnostic management of individual execution environments is added to the platform,
+ * installation will be (optionally) specific to a single execution environment.
+ */
+public abstract class TruffleTool {
+
+    private enum ToolState {
+        UNINSTALLED,
+        ENABLED_INSTALLED,
+        DISABLED_INSTALLED,
+        DISPOSED;
+    }
+
+    private ToolState toolState = ToolState.UNINSTALLED;
+
+    protected TruffleTool() {
+
+    }
+
+    /**
+     * Connect the tool to some part of the Truffle runtime, and enable data collection to start.
+     * Instrumentation will only be added to subsequently created ASTs.
+     *
+     * @throws IllegalStateException if the tool has previously been installed.
+     */
+    public final void install() {
+        if (toolState != ToolState.UNINSTALLED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " has already been installed");
+        }
+        if (internalInstall()) {
+            toolState = ToolState.ENABLED_INSTALLED;
+        }
+    }
+
+    /**
+     * @return whether the tool is currently collecting data.
+     */
+    public final boolean isEnabled() {
+        return toolState == ToolState.ENABLED_INSTALLED;
+    }
+
+    /**
+     * Switches tool state between <em>enabled</em> (collecting data) and <em>disabled</em> (not
+     * collecting data, but keeping data already collected).
+     *
+     * @throws IllegalStateException if not yet installed or disposed.
+     */
+    public final void setEnabled(boolean isEnabled) {
+        if (toolState == ToolState.UNINSTALLED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " not yet installed");
+        }
+        if (toolState == ToolState.DISPOSED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " has been disposed");
+        }
+        internalSetEnabled(isEnabled);
+        toolState = isEnabled ? ToolState.ENABLED_INSTALLED : ToolState.DISABLED_INSTALLED;
+    }
+
+    /**
+     * Clears any data already collected, but otherwise does not change the state of the tool.
+     *
+     * @throws IllegalStateException if not yet installed or disposed.
+     */
+    public final void reset() {
+        if (toolState == ToolState.UNINSTALLED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " not yet installed");
+        }
+        if (toolState == ToolState.DISPOSED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " has been disposed");
+        }
+        internalReset();
+    }
+
+    /**
+     * Makes the tool permanently <em>disabled</em>, removes instrumentation, but keeps data already
+     * collected.
+     *
+     * @throws IllegalStateException if not yet installed or disposed.
+     */
+    public final void dispose() {
+        if (toolState == ToolState.UNINSTALLED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " not yet installed");
+        }
+        if (toolState == ToolState.DISPOSED) {
+            throw new IllegalStateException("Tool " + getClass().getSimpleName() + " has been disposed");
+        }
+        internalDispose();
+        toolState = ToolState.DISPOSED;
+    }
+
+    /**
+     * @return whether the installation succeeded.
+     */
+    protected abstract boolean internalInstall();
+
+    /**
+     * No subclass action required.
+     * 
+     * @param isEnabled
+     */
+    protected void internalSetEnabled(boolean isEnabled) {
+    }
+
+    protected abstract void internalReset();
+
+    protected abstract void internalDispose();
+
+}

--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/LineToProbesMap.java	Tue Jan 27 20:25:26 2015 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,176 +0,0 @@
-/*
- * Copyright (c) 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.io.*;
-import java.util.*;
-
-import com.oracle.truffle.api.instrument.*;
-import com.oracle.truffle.api.instrument.Probe.ProbeListener;
-import com.oracle.truffle.api.source.*;
-
-/**
- * A mapping from {@link LineLocation} (a line number in a specific piece of {@link Source} code) to
- * a collection of {@link Probe}s whose associated {@link SourceSection} starts on that line.
- */
-public class LineToProbesMap implements ProbeListener {
-
-    private static final boolean TRACE = false;
-    private static final PrintStream OUT = System.out;
-
-    private static void trace(String msg) {
-        OUT.println("LineToProbesMap: " + msg);
-    }
-
-    /**
-     * Map: Source line ==> probes associated with source sections starting on the line.
-     */
-    private final Map<LineLocation, Collection<Probe>> lineToProbesMap = new HashMap<>();
-
-    public LineToProbesMap() {
-    }
-
-    public void startASTProbing(Source source) {
-    }
-
-    public void newProbeInserted(Probe probe) {
-        final SourceSection sourceSection = probe.getProbedSourceSection();
-        if (sourceSection != null && !(sourceSection instanceof NullSourceSection)) {
-            final LineLocation lineLocation = sourceSection.getLineLocation();
-            if (TRACE) {
-                trace("ADD " + lineLocation.getShortDescription() + " ==> " + probe.getShortDescription());
-            }
-            this.addProbeToLine(lineLocation, probe);
-        }
-    }
-
-    public void probeTaggedAs(Probe probe, SyntaxTag tag, Object tagValue) {
-        // This map ignores tags
-    }
-
-    public void endASTProbing(Source source) {
-    }
-
-    /**
-     * Returns the {@link Probe}, if any, associated with source that starts on a specified line; if
-     * there are more than one, return the one with the first starting character location.
-     */
-    public Probe findLineProbe(LineLocation lineLocation) {
-        Probe probe = null;
-        final Collection<Probe> probes = getProbesAtLine(lineLocation);
-        for (Probe probesOnLine : probes) {
-            if (probe == null) {
-                probe = probesOnLine;
-            } else if (probesOnLine.getProbedSourceSection().getCharIndex() < probe.getProbedSourceSection().getCharIndex()) {
-                probe = probesOnLine;
-            }
-        }
-        return probe;
-    }
-
-    /**
-     * Records creation of a probe whose associated source starts on the given line.
-     * <p>
-     * If the line already exists in the internal {@link #lineToProbesMap}, this probe will be added
-     * to the existing collection. If no line already exists in the internal map, then a new key is
-     * added along with a new collection containing the probe.
-     * <p>
-     * This class requires that each added line/probe pair hasn't been previously added. However,
-     * attaching the same probe to a new line location is allowed.
-     *
-     * @param line The {@link LineLocation} to attach the probe to.
-     * @param probe The {@link Probe} to attach for that line location.
-     */
-    protected void addProbeToLine(LineLocation line, Probe probe) {
-
-        if (!lineToProbesMap.containsKey(line)) {
-            // Key does not exist, add new probe list
-            final ArrayList<Probe> newProbeList = new ArrayList<>(2);
-            newProbeList.add(probe);
-            lineToProbesMap.put(line, newProbeList);
-        } else {
-            // Probe list exists, add to existing
-            final Collection<Probe> existingProbeList = lineToProbesMap.get(line);
-            assert !existingProbeList.contains(probe);
-            existingProbeList.add(probe);
-        }
-    }
-
-    /**
-     *
-     * Returns a collection of {@link Probe}s whose associated source begins at the given
-     * {@link LineLocation}, an empty list if none.
-     *
-     * @param line The line to check.
-     * @return A collection of probes at the given line.
-     */
-    public Collection<Probe> getProbesAtLine(LineLocation line) {
-        Collection<Probe> probesList = lineToProbesMap.get(line);
-
-        if (probesList == null) {
-            return Collections.emptyList();
-        }
-        return probesList;
-    }
-
-    /**
-     * Convenience method to get probes according to a int line number. Returns a collection of
-     * {@link Probe}s at the given line number, an empty list if none.
-     *
-     * @param lineNumber The line number to check.
-     * @return A collection of probes at the given line.
-     */
-    public Collection<Probe> getProbesAtLineNumber(int lineNumber) {
-
-        final Set<LineLocation> keySet = lineToProbesMap.keySet();
-        if (keySet.size() == 0) {
-            return Collections.emptyList();
-        }
-
-        ArrayList<Probe> probes = new ArrayList<>();
-        for (LineLocation line : keySet) {
-            if (line.getLineNumber() == lineNumber) {
-                probes.addAll(lineToProbesMap.get(line));
-            }
-        }
-
-        return probes;
-    }
-
-    public void forget(Source source) {
-        final Set<LineLocation> mappedLines = lineToProbesMap.keySet();
-        if (mappedLines.size() > 0) {
-            List<LineLocation> forgetLines = new ArrayList<>();
-            for (LineLocation line : mappedLines) {
-                if (line.getSource().equals(source)) {
-                    forgetLines.add(line);
-                }
-            }
-            for (LineLocation line : forgetLines) {
-                lineToProbesMap.remove(line);
-            }
-        }
-    }
-}

--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/impl/LineToSourceSectionMap.java	Tue Jan 27 20:25:26 2015 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,143 +0,0 @@
-/*
- * Copyright (c) 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.io.*;
-import java.util.*;
-
-import com.oracle.truffle.api.instrument.*;
-import com.oracle.truffle.api.instrument.Probe.*;
-import com.oracle.truffle.api.source.*;
-
-/**
- * A mapping from {@link LineLocation} (a line number in a specific piece of {@link Source} code) to
- * a collection of {@link SourceSection}s that exist on that line. This class assumes that all nodes
- * are instrumented as it uses the {@link ProbeListener} interface to determine the source sections
- * that exist in the file.
- */
-public class LineToSourceSectionMap implements ProbeListener {
-
-    private static final boolean TRACE = false;
-    private static final PrintStream OUT = System.out;
-
-    private static void trace(String msg) {
-        OUT.println("LineToSourceSectionMap: " + msg);
-    }
-
-    /**
-     * Map: Source line ==> source sections that exist on the line.
-     */
-    private final Map<LineLocation, Collection<SourceSection>> lineToSourceSectionsMap = new HashMap<>();
-
-    public LineToSourceSectionMap() {
-    }
-
-    public void startASTProbing(Source source) {
-    }
-
-    public void newProbeInserted(Probe probe) {
-        final SourceSection sourceSection = probe.getProbedSourceSection();
-        if (sourceSection != null && !(sourceSection instanceof NullSourceSection)) {
-            final LineLocation lineLocation = sourceSection.getLineLocation();
-            if (TRACE) {
-                trace("NEW " + lineLocation.getShortDescription() + " Probe=" + probe);
-            }
-            this.addSourceSectionToLine(lineLocation, sourceSection);
-        }
-    }
-
-    public void probeTaggedAs(Probe probe, SyntaxTag tag, Object tagValue) {
-        // This map ignores tags, but this subclasses can override this method to operate on tags.
-    }
-
-    public void endASTProbing(Source source) {
-    }
-
-    /**
-     * Adds a source section to the given line.
-     * <p>
-     * If the line already exists in the internal {@link #lineToSourceSectionsMap}, this source
-     * section will be added to the existing collection. If no line already exists in the internal
-     * map, then a new key is added along with a new collection containing the source section.
-     * <p>
-     * This class does not check if a source section has already been added to a line.
-     *
-     * @param line The {@link LineLocation} to attach the source section to.
-     * @param sourceSection The {@link SourceSection} to attach for that line location.
-     */
-    protected void addSourceSectionToLine(LineLocation line, SourceSection sourceSection) {
-        if (!lineToSourceSectionsMap.containsKey(line)) {
-            // Key does not exist, add new source section list
-            final ArrayList<SourceSection> newSourceSectionList = new ArrayList<>(2);
-            newSourceSectionList.add(sourceSection);
-            lineToSourceSectionsMap.put(line, newSourceSectionList);
-        } else {
-            // Source section list exists, add to existing
-            final Collection<SourceSection> existingSourceSectionList = lineToSourceSectionsMap.get(line);
-            existingSourceSectionList.add(sourceSection);
-        }
-    }
-
-    /**
-     * Returns a collection of {@link SourceSection}s at the given {@link LineLocation}, an empty
-     * list if none.
-     *
-     * @param line The line to check.
-     * @return the source sections at the given line.
-     */
-    public Collection<SourceSection> getSourceSectionsAtLine(LineLocation line) {
-        Collection<SourceSection> sourceSectionList = lineToSourceSectionsMap.get(line);
-
-        if (sourceSectionList == null) {
-            return Collections.emptyList();
-        }
-        return sourceSectionList;
-    }
-
-    /**
-     * Convenience method to get source sections according to a int line number. Returns a
-     * collection of {@link SourceSection}s at the given line number. If there are no source
-     * sections at that line, an empty list is returned.
-     *
-     * @param lineNumber The line number to check.
-     * @return A collection of source sections at the given line.
-     */
-    public Collection<SourceSection> getSourceSectionsAtLineNumber(int lineNumber) {
-
-        final Set<LineLocation> keySet = lineToSourceSectionsMap.keySet();
-        if (keySet.size() == 0) {
-            return Collections.emptyList();
-        }
-
-        final ArrayList<SourceSection> sourceSections = new ArrayList<>();
-        for (LineLocation line : keySet) {
-            if (line.getLineNumber() == lineNumber) {
-                sourceSections.addAll(lineToSourceSectionsMap.get(line));
-            }
-        }
-
-        return sourceSections;
-    }
-}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/tools/CoverageTracker.java	Tue Jan 27 20:26:41 2015 -0800
@@ -0,0 +1,317 @@
+/*
+ * Copyright (c) 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.  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.tools;
+
+import java.io.*;
+import java.util.*;
+import java.util.Map.Entry;
+import java.util.concurrent.atomic.*;
+
+import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.instrument.impl.*;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.api.nodes.Node.Child;
+import com.oracle.truffle.api.source.*;
+
+/**
+ * A {@link TruffleTool} that counts interpreter <em>execution calls</em> to AST nodes that hold a
+ * specified {@linkplain SyntaxTag tag}, tabulated by source and line number associated with each
+ * node. Tags are presumed to be applied external to the tool. If no tag is specified,
+ * {@linkplain StandardSyntaxTag#STATEMENT STATEMENT} is used, corresponding to conventional
+ * behavior for code coverage tools.
+ * <p>
+ * <b>Tool Life Cycle</b>
+ * <p>
+ * See {@link TruffleTool} for the life cycle common to all such tools.
+ * <p>
+ * <b>Execution Counts</b>
+ * <p>
+ * <ul>
+ * <li>"Execution call" on a node is is defined as invocation of a node method that is instrumented
+ * to produce the event {@link TruffleEventReceiver#enter(Node, VirtualFrame)};</li>
+ * <li>Execution calls are tabulated only at <em>instrumented</em> nodes, i.e. those for which
+ * {@linkplain Node#isInstrumentable() isInstrumentable() == true};</li>
+ * <li>Execution calls are tabulated only at nodes present in the AST when originally created;
+ * dynamically added nodes will not be instrumented.</li>
+ * </ul>
+ * </p>
+ * <b>Results</b>
+ * <p>
+ * A modification-safe copy of the {@linkplain #getCounts() counts} can be retrieved at any time,
+ * without effect on the state of the tool.
+ * </p>
+ * <p>
+ * A "default" {@linkplain #print(PrintStream) print()} method can summarizes the current counts at
+ * any time in a simple textual format, with no other effect on the state of the tool.
+ * </p>
+ *
+ * @see Instrument
+ * @see SyntaxTag
+ */
+public final class CoverageTracker extends TruffleTool {
+
+    /** Counting data. */
+    private final Map<LineLocation, CoverageCounter> counters = new HashMap<>();
+
+    /** For disposal. */
+    private final List<Instrument> instruments = new ArrayList<>();
+
+    /**
+     * Counting is restricted to nodes holding this tag.
+     */
+    private final SyntaxTag countingTag;
+
+    private final ProbeListener probeListener;
+
+    /**
+     * Create a per-line coverage tool for nodes tagged as {@linkplain StandardSyntaxTag#STATEMENT
+     * statements} in subsequently created ASTs.
+     */
+    public CoverageTracker() {
+        this(StandardSyntaxTag.STATEMENT);
+    }
+
+    /**
+     * Create a per-line coverage tool for nodes tagged as specified, presuming that tags applied
+     * outside this tool.
+     */
+    public CoverageTracker(SyntaxTag tag) {
+        this.probeListener = new CoverageProbeListener();
+        this.countingTag = tag;
+    }
+
+    @Override
+    protected boolean internalInstall() {
+        Probe.addProbeListener(probeListener);
+        return true;
+    }
+
+    @Override
+    protected void internalReset() {
+        counters.clear();
+    }
+
+    @Override
+    protected void internalDispose() {
+        Probe.removeProbeListener(probeListener);
+        for (Instrument instrument : instruments) {
+            instrument.dispose();
+        }
+    }
+
+    /**
+     * Gets a modification-safe summary of the current per-type node execution counts; does not
+     * affect the counts.
+     * <p>
+     * The map holds an array for each source, and elements of the a array corresponding to the
+     * textual lines of that source. An array entry contains null if the corresponding line of
+     * source is associated with no nodes of the relevant type, i.e. where no count was made. A
+     * numeric entry represents the execution count at the corresponding line of source.
+     * <p>
+     * <b>Note:</b> source line numbers are 1-based, so array index {@code i} corresponds to source
+     * line number {@code i + 1}
+     */
+    public Map<Source, Long[]> getCounts() {
+
+        /**
+         * Counters for every {Source, line number} for which a counter was installed, i.e. for
+         * every line associated with an appropriately tagged AST node; iterable in order of source
+         * name, then line number.
+         */
+        final TreeSet<Entry<LineLocation, CoverageCounter>> entries = new TreeSet<>(new LineLocationEntryComparator());
+
+        final Map<Source, Long[]> results = new HashMap<>();
+
+        for (Entry<LineLocation, CoverageCounter> entry : counters.entrySet()) {
+            entries.add(entry);
+        }
+        Source curSource = null;
+        Long[] curLineTable = null;
+        for (Entry<LineLocation, CoverageCounter> entry : entries) {
+            final LineLocation key = entry.getKey();
+            final Source source = key.getSource();
+            final int lineNo = key.getLineNumber();
+            if (source != curSource) {
+                if (curSource != null) {
+                    results.put(curSource, curLineTable);
+                }
+                curSource = source;
+                curLineTable = new Long[source.getLineCount()];
+            }
+            curLineTable[lineNo - 1] = entry.getValue().count.longValue();
+        }
+        if (curSource != null) {
+            results.put(curSource, curLineTable);
+        }
+        return results;
+    }
+
+    /**
+     * A default printer for the current line counts, producing lines of the form " (<count>) <line
+     * number> : <text of line>", grouped by source.
+     */
+    public void print(PrintStream out) {
+        out.println();
+        out.println(countingTag.name() + " coverage:");
+
+        /**
+         * Counters for every {Source, line number} for which a counter was installed, i.e. for
+         * every line associated with an appropriately tagged AST node; iterable in order of source
+         * name, then line number.
+         */
+        final TreeSet<Entry<LineLocation, CoverageCounter>> entries = new TreeSet<>(new LineLocationEntryComparator());
+
+        for (Entry<LineLocation, CoverageCounter> entry : counters.entrySet()) {
+            entries.add(entry);
+        }
+        Source curSource = null;
+        int curLineNo = 1;
+        for (Entry<LineLocation, CoverageCounter> entry : entries) {
+            final LineLocation key = entry.getKey();
+            final Source source = key.getSource();
+            final int lineNo = key.getLineNumber();
+            if (source != curSource) {
+                if (curSource != null) {
+                    while (curLineNo <= curSource.getLineCount()) {
+                        displayLine(out, null, curSource, curLineNo++);
+                    }
+                }
+                curSource = source;
+                curLineNo = 1;
+                out.println();
+                out.println(source.getPath());
+            }
+            while (curLineNo < lineNo) {
+                displayLine(out, null, curSource, curLineNo++);
+            }
+            displayLine(out, entry.getValue().count, curSource, curLineNo++);
+        }
+        if (curSource != null) {
+            while (curLineNo <= curSource.getLineCount()) {
+                displayLine(out, null, curSource, curLineNo++);
+            }
+        }
+    }
+
+    private static void displayLine(PrintStream out, AtomicLong value, Source source, int lineNo) {
+        if (value == null) {
+            out.format("%14s", " ");
+        } else {
+            out.format("(%12d)", value.longValue());
+        }
+        out.format(" %3d: ", lineNo);
+        out.println(source.getCode(lineNo));
+    }
+
+    /**
+     * A receiver for events at each instrumented AST location. This receiver counts
+     * "execution calls" to the instrumented node and is <em>stateful</em>. State in receivers must
+     * be considered carefully since ASTs, along with all instrumentation (including event receivers
+     * such as this) are routinely cloned by the Truffle runtime. AST cloning is <em>shallow</em>
+     * (for non- {@link Child} nodes), so in this case the actual count <em>is shared</em> among all
+     * the clones; the count is also held in a table indexed by source line.
+     * <p>
+     * In contrast, a primitive field would <em>not</em> be shared among clones and resulting counts
+     * would not be accurate.
+     */
+    private final class CoverageEventReceiver extends DefaultEventReceiver {
+
+        /**
+         * Shared by all clones of the associated instrument and by the table of counters for the
+         * line.
+         */
+        private final AtomicLong count;
+
+        CoverageEventReceiver(AtomicLong count) {
+            this.count = count;
+        }
+
+        @Override
+        @TruffleBoundary
+        public void enter(Node node, VirtualFrame frame) {
+            if (isEnabled()) {
+                count.getAndIncrement();
+            }
+        }
+    }
+
+    private static final class LineLocationEntryComparator implements Comparator<Entry<LineLocation, CoverageCounter>> {
+
+        public int compare(Entry<LineLocation, CoverageCounter> e1, Entry<LineLocation, CoverageCounter> e2) {
+            return LineLocation.COMPARATOR.compare(e1.getKey(), e2.getKey());
+        }
+    }
+
+    /**
+     * Attach a counting instrument to each node that is assigned a specified tag.
+     */
+    private class CoverageProbeListener extends DefaultProbeListener {
+
+        @Override
+        public void probeTaggedAs(Probe probe, SyntaxTag tag, Object tagValue) {
+            if (countingTag == tag) {
+
+                final SourceSection srcSection = probe.getProbedSourceSection();
+                if (srcSection == null) {
+                    // TODO (mlvdv) report this?
+                } else {
+                    final LineLocation lineLocation = srcSection.getLineLocation();
+                    CoverageCounter counter = counters.get(lineLocation);
+                    if (counter != null) {
+                        // Another node starts on same line; count only the first (textually)
+                        if (srcSection.getCharIndex() > counter.srcSection.getCharIndex()) {
+                            // Counter already in place, corresponds to code earlier on line
+                            return;
+                        } else {
+                            // Counter already in place, corresponds to later code; replace it
+                            counter.instrument.dispose();
+                        }
+                    }
+                    final AtomicLong count = new AtomicLong();
+                    final CoverageEventReceiver eventReceiver = new CoverageEventReceiver(count);
+                    final Instrument instrument = Instrument.create(eventReceiver, CoverageTracker.class.getSimpleName());
+                    instruments.add(instrument);
+                    probe.attach(instrument);
+                    counters.put(lineLocation, new CoverageCounter(srcSection, instrument, count));
+                }
+            }
+        }
+    }
+
+    private class CoverageCounter {
+        final SourceSection srcSection;
+        final Instrument instrument;
+        final AtomicLong count;
+
+        CoverageCounter(SourceSection srcSection, Instrument instrument, AtomicLong count) {
+            this.srcSection = srcSection;
+            this.instrument = instrument;
+            this.count = count;
+        }
+    }
+
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/tools/LineToProbesMap.java	Tue Jan 27 20:26:41 2015 -0800
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2014, 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.  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.tools;
+
+import java.io.*;
+import java.util.*;
+
+import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.instrument.impl.*;
+import com.oracle.truffle.api.source.*;
+
+/**
+ * A {@link TruffleTool} that builds a map of every {@Probe} attached to some AST, indexed
+ * by {@link Source} and line number.
+ */
+public final class LineToProbesMap extends TruffleTool {
+
+    private static final boolean TRACE = false;
+    private static final PrintStream OUT = System.out;
+
+    private static void trace(String msg) {
+        OUT.println("LineToProbesMap: " + msg);
+    }
+
+    /**
+     * Map: Source line ==> probes associated with source sections starting on the line.
+     */
+    private final Map<LineLocation, Collection<Probe>> lineToProbesMap = new HashMap<>();
+
+    private final ProbeListener probeListener;
+
+    /**
+     * Create a map of {@link Probe}s that collects information on all probes added to subsequently
+     * created ASTs (once installed).
+     */
+    public LineToProbesMap() {
+        this.probeListener = new LineToProbesListener();
+    }
+
+    @Override
+    protected boolean internalInstall() {
+        Probe.addProbeListener(probeListener);
+        return true;
+    }
+
+    @Override
+    protected void internalReset() {
+        lineToProbesMap.clear();
+    }
+
+    @Override
+    protected void internalDispose() {
+        Probe.removeProbeListener(probeListener);
+    }
+
+    /**
+     * Returns the {@link Probe}, if any, associated with a specific line of guest language code; if
+     * more than one, return the one with the first starting character location.
+     */
+    public Probe findFirstProbe(LineLocation lineLocation) {
+        Probe probe = null;
+        final Collection<Probe> probes = findProbes(lineLocation);
+        for (Probe probesOnLine : probes) {
+            if (probe == null) {
+                probe = probesOnLine;
+            } else if (probesOnLine.getProbedSourceSection().getCharIndex() < probe.getProbedSourceSection().getCharIndex()) {
+                probe = probesOnLine;
+            }
+        }
+        return probe;
+    }
+
+    /**
+     * Returns all {@link Probe}s whose associated source begins at the given {@link LineLocation},
+     * an empty list if none.
+     */
+    public Collection<Probe> findProbes(LineLocation line) {
+        final Collection<Probe> probes = lineToProbesMap.get(line);
+        if (probes == null) {
+            return Collections.emptyList();
+        }
+        return Collections.unmodifiableCollection(probes);
+    }
+
+    private class LineToProbesListener extends DefaultProbeListener {
+
+        @Override
+        public void newProbeInserted(Probe probe) {
+            final SourceSection sourceSection = probe.getProbedSourceSection();
+            if (sourceSection != null && !(sourceSection instanceof NullSourceSection)) {
+                final LineLocation lineLocation = sourceSection.getLineLocation();
+                if (TRACE) {
+                    trace("ADD " + lineLocation.getShortDescription() + " ==> " + probe.getShortDescription());
+                }
+                Collection<Probe> probes = lineToProbesMap.get(lineLocation);
+                if (probes == null) {
+                    probes = new ArrayList<>(2);
+                    lineToProbesMap.put(lineLocation, probes);
+                } else {
+                    assert !probes.contains(probe);
+                }
+                probes.add(probe);
+            }
+        }
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/tools/NodeExecCounter.java	Tue Jan 27 20:26:41 2015 -0800
@@ -0,0 +1,315 @@
+/*
+ * Copyright (c) 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.  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.tools;
+
+import java.io.*;
+import java.util.*;
+import java.util.concurrent.atomic.*;
+
+import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.*;
+import com.oracle.truffle.api.instrument.impl.*;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.api.nodes.Node.Child;
+
+/**
+ * A {@link TruffleTool} that counts interpreter <em>execution calls</em> to AST nodes, tabulated by
+ * the type of called nodes; counting can be enabled <em>all</em> nodes or restricted to nodes with
+ * a specified {@linkplain SyntaxTag tag} that is presumed to be applied external to the tool.
+ * <p>
+ * <b>Tool Life Cycle</b>
+ * <p>
+ * See {@link TruffleTool} for the life cycle common to all such tools.
+ * </p>
+ * <b>Execution Counts</b>
+ * <p>
+ * <ul>
+ * <li>"Execution call" on a node is is defined as invocation of a node method that is instrumented
+ * to produce the event {@link TruffleEventReceiver#enter(Node, VirtualFrame)};</li>
+ * <li>Execution calls are tabulated only at <em>instrumented</em> nodes, i.e. those for which
+ * {@linkplain Node#isInstrumentable() isInstrumentable() == true};</li>
+ * <li>Execution calls are tabulated only at nodes present in the AST when originally created;
+ * dynamically added nodes will not be instrumented.</li>
+ * </ul>
+ * </p>
+ * <b>Failure Log</b>
+ * <p>
+ * For the benefit of language implementors, the tool maintains a log describing failed attempts to
+ * probe AST nodes. Most failures occur when the type of the wrapper created by
+ * {@link Node#createWrapperNode()} is not assignable to the relevant {@link Child} field in the
+ * node's parent.
+ * </p>
+ * <p>
+ * {@linkplain #reset() Resetting} the counts has no effect on the failure log.
+ * </p>
+ * <b>Results</b>
+ * <p>
+ * A modification-safe copy of the {@linkplain #getCounts() counts} can be retrieved at any time,
+ * without effect on the state of the tool.
+ * </p>
+ * <p>
+ * A "default" {@linkplain #print(PrintStream) print()} method can summarizes the current counts at
+ * any time in a simple textual format, without effect on the state of the tool.
+ * </p>
+ *
+ * @see Instrument
+ * @see SyntaxTag
+ * @see ProbeFailure
+ */
+public final class NodeExecCounter extends TruffleTool {
+
+    /**
+     * Execution count for AST nodes of a particular type.
+     */
+    public interface NodeExecutionCount {
+        Class<?> nodeClass();
+
+        long executionCount();
+    }
+
+    /**
+     * Receiver for events at instrumented nodes. Counts are maintained in a shared table, so the
+     * receiver is stateless and can be shared by every {@link Instrument}.
+     */
+    private final TruffleEventReceiver eventReceiver = new DefaultEventReceiver() {
+        @Override
+        @TruffleBoundary
+        public void enter(Node node, VirtualFrame frame) {
+            if (isEnabled()) {
+                final Class<?> nodeClass = node.getClass();
+                AtomicLong nodeCounter = counters.get(nodeClass);
+                if (nodeCounter == null) {
+                    nodeCounter = new AtomicLong();
+                    counters.put(nodeClass, nodeCounter);
+                }
+                nodeCounter.getAndIncrement();
+            }
+        }
+    };
+
+    /** Counting data. */
+    private final Map<Class<?>, AtomicLong> counters = new HashMap<>();
+
+    /** Failure log. */
+    private final List<ProbeFailure> failures = new ArrayList<>();
+
+    /** For disposal. */
+    private final List<Instrument> instruments = new ArrayList<>();
+
+    /**
+     * If non-null, counting is restricted to nodes holding this tag.
+     */
+    private final SyntaxTag countingTag;
+
+    /**
+     * Prober used only when instrumenting every node.
+     */
+    private ASTProber astProber;
+
+    /**
+     * Listener used only when restricting counting to a specific tag.
+     */
+    private ProbeListener probeListener;
+
+    /**
+     * Create a per node-type execution counting tool for all nodes in subsequently created ASTs.
+     */
+    public NodeExecCounter() {
+        this.countingTag = null;
+    }
+
+    /**
+     * Creates a per-type execution counting for nodes tagged as specified in subsequently created
+     * ASTs.
+     */
+    public NodeExecCounter(SyntaxTag tag) {
+        this.countingTag = tag;
+    }
+
+    @Override
+    protected boolean internalInstall() {
+        if (countingTag == null) {
+            astProber = new ExecCounterASTProber();
+            Probe.registerASTProber(astProber);
+        } else {
+            probeListener = new NodeExecCounterProbeListener();
+            Probe.addProbeListener(probeListener);
+        }
+        return true;
+    }
+
+    @Override
+    protected void internalReset() {
+        counters.clear();
+        failures.clear();
+    }
+
+    @Override
+    protected void internalDispose() {
+        if (astProber != null) {
+            Probe.unregisterASTProber(astProber);
+        }
+        if (probeListener != null) {
+            Probe.removeProbeListener(probeListener);
+        }
+        for (Instrument instrument : instruments) {
+            instrument.dispose();
+        }
+    }
+
+    /**
+     * Gets a modification-safe summary of the current per-type node execution counts; does not
+     * affect the counts.
+     */
+    public NodeExecutionCount[] getCounts() {
+        final Collection<Map.Entry<Class<?>, AtomicLong>> entrySet = counters.entrySet();
+        final NodeExecutionCount[] result = new NodeExecCountImpl[entrySet.size()];
+        int i = 0;
+        for (Map.Entry<Class<?>, AtomicLong> entry : entrySet) {
+            result[i++] = new NodeExecCountImpl(entry.getKey(), entry.getValue().longValue());
+        }
+        return result;
+    }
+
+    /**
+     * Gets a log containing a report of every failed attempt to instrument a node.
+     */
+    public ProbeFailure[] getFailures() {
+        return failures.toArray(new ProbeFailure[failures.size()]);
+    }
+
+    /**
+     * A default printer for the current counts, producing lines of the form
+     * " <count> : <node type>" in descending order of count.
+     */
+    public void print(PrintStream out) {
+        print(out, false);
+    }
+
+    /**
+     * A default printer for the current counts, producing lines of the form
+     * " <count> : <node type>" in descending order of count.
+     *
+     * @param out
+     * @param verbose whether to describe nodes on which instrumentation failed
+     */
+    public void print(PrintStream out, boolean verbose) {
+
+        final long missedNodes = failures.size();
+        out.println();
+        if (countingTag == null) {
+            out.println("Execution counts by node type:");
+        } else {
+            out.println("\"" + countingTag.name() + "\"-tagged execution counts by node type:");
+        }
+        final StringBuilder disclaim = new StringBuilder("(");
+        if (missedNodes > 0) {
+            disclaim.append(Long.toString(missedNodes) + " original AST nodes not instrumented, ");
+        }
+        disclaim.append("dynamically added nodes not instrumented)");
+        out.println(disclaim.toString());
+        NodeExecutionCount[] execCounts = getCounts();
+        // Sort in descending order
+        Arrays.sort(execCounts, new Comparator<NodeExecutionCount>() {
+
+            public int compare(NodeExecutionCount o1, NodeExecutionCount o2) {
+                return Long.compare(o2.executionCount(), o1.executionCount());
+            }
+
+        });
+        for (NodeExecutionCount nodeCount : execCounts) {
+            out.format("%12d", nodeCount.executionCount());
+            out.println(" : " + nodeCount.nodeClass().getName());
+        }
+
+        if (verbose && missedNodes > 0) {
+            out.println("Instrumentation failures for execution counts:");
+
+            for (ProbeFailure failure : failures) {
+                out.println("\t" + failure.getMessage());
+            }
+        }
+    }
+
+    /**
+     * A prober that attempts to probe and instrument every node.
+     */
+    private class ExecCounterASTProber implements ASTProber, NodeVisitor {
+
+        public boolean visit(Node node) {
+
+            if (node.isInstrumentable()) {
+                try {
+                    final Instrument instrument = Instrument.create(eventReceiver, "NodeExecCounter");
+                    instruments.add(instrument);
+                    node.probe().attach(instrument);
+                } catch (ProbeException ex) {
+                    failures.add(ex.getFailure());
+                }
+            }
+            return true;
+        }
+
+        public void probeAST(Node node) {
+            node.accept(this);
+        }
+    }
+
+    /**
+     * A listener that assumes ASTs have been tagged external to this tool, and which instruments
+     * nodes holding a specified tag.
+     */
+    private class NodeExecCounterProbeListener extends DefaultProbeListener {
+
+        @Override
+        public void probeTaggedAs(Probe probe, SyntaxTag tag, Object tagValue) {
+            if (countingTag == tag) {
+                final Instrument instrument = Instrument.create(eventReceiver, NodeExecCounter.class.getSimpleName());
+                instruments.add(instrument);
+                probe.attach(instrument);
+            }
+        }
+    }
+
+    private static class NodeExecCountImpl implements NodeExecutionCount {
+
+        private final Class<?> nodeClass;
+        private final long count;
+
+        public NodeExecCountImpl(Class<?> nodeClass, long count) {
+            this.nodeClass = nodeClass;
+            this.count = count;
+        }
+
+        public Class<?> nodeClass() {
+            return nodeClass;
+        }
+
+        public long executionCount() {
+            return count;
+        }
+    }
+}