--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/truffle/com.oracle.truffle.tools/src/com/oracle/truffle/tools/NodeExecCounter.java	Wed Jun 17 10:58:08 2015 +0200
@@ -0,0 +1,332 @@
+/*
+ * 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.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;
+
+/**
+ * An {@link InstrumentationTool} 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 InstrumentationTool} 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 StandardInstrumentListener#enter(Probe, 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 InstrumentationTool {
+
+    /**
+     * Execution count for AST nodes of a particular type.
+     */
+    public interface NodeExecutionCount {
+        Class<?> nodeClass();
+
+        long executionCount();
+    }
+
+    /**
+     * Listener for events at instrumented nodes. Counts are maintained in a shared table, so the
+     * listener is stateless and can be shared by every {@link Instrument}.
+     */
+    private final StandardInstrumentListener instrumentListener = new DefaultStandardInstrumentListener() {
+        @Override
+        public void enter(Probe probe, Node node, VirtualFrame vFrame) {
+            if (isEnabled()) {
+                final Class<?> nodeClass = node.getClass();
+                /*
+                 * Everything up to here is inlined by Truffle compilation. Delegate the next part
+                 * to a method behind an inlining boundary.
+                 * 
+                 * Note that it is not permitted to pass a {@link VirtualFrame} across an inlining
+                 * boundary; they are truly virtual in inlined code.
+                 */
+                AtomicLong nodeCounter = getCounter(nodeClass);
+                nodeCounter.getAndIncrement();
+            }
+        }
+
+        /**
+         * Mark this method as a boundary that will stop Truffle inlining, which should not be
+         * allowed to inline the hash table method or any other complex library code.
+         */
+        @TruffleBoundary
+        private AtomicLong getCounter(Class<?> nodeClass) {
+            AtomicLong nodeCounter = counters.get(nodeClass);
+            if (nodeCounter == null) {
+                nodeCounter = new AtomicLong();
+                counters.put(nodeClass, nodeCounter);
+            }
+            return nodeCounter;
+        }
+    };
+
+    /** 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(instrumentListener, "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(instrumentListener, 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;
+        }
+    }
+}