Mercurial > hg > graal-compiler
view graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Instrument.java @ 18750:8a758dce7d80
Truffle: added new deepCopy method to Node.
author | Christian Humer <christian.humer@gmail.com> |
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date | Mon, 29 Dec 2014 23:38:08 +0100 |
parents | e3c95cbbb50c |
children | 867058575979 |
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/* * 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; import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary; import com.oracle.truffle.api.*; import com.oracle.truffle.api.frame.*; import com.oracle.truffle.api.instrument.impl.*; import com.oracle.truffle.api.nodes.*; // TODO (mlvdv) migrate some of this to external documentation. /** * A dynamically added/removed binding between a {@link Probe}, which provides notification of * {@linkplain TruffleEventReceiver execution events} taking place at a {@link Node} in a Guest * Language (GL) Truffle AST, and a {@linkplain TruffleEventReceiver receiver}, which consumes * notifications on behalf of an external tool. * <p> * <h4>Summary: How to "instrument" an AST location:</h4> * <ol> * <li>Create an implementation of {@link TruffleEventReceiver} that responds to events on behalf of * a tool.</li> * <li>Create an Instrument via factory method {@link Instrument#create(TruffleEventReceiver)}.</li> * <li>"Attach" the Instrument to a Probe via {@link Probe#attach(Instrument)}, at which point event * notifications begin to arrive at the receiver.</li> * <li>When no longer needed, "detach" the Instrument via {@link Instrument#dispose()}, at which * point event notifications to the receiver cease, and the Instrument becomes unusable.</li> * </ol> * <p> * <h4>Options for creating receivers:</h4> * <p> * <ol> * <li>Implement the interface {@link TruffleEventReceiver}. The event handling methods account for * both the entry into an AST node (about to call) and several possible kinds of exit from an AST * node (just returned).</li> * <li>Extend {@link DefaultEventReceiver}, which provides a no-op implementation of every * {@link TruffleEventReceiver} method; override the methods of interest.</li> * <li>Extend {@link SimpleEventReceiver}, where return values are ignored so only two methods (for * "enter" and "return") will notify all events.</li> * </ol> * <p> * <h4>General guidelines for receiver implementation:</h4> * <p> * When an Instrument is attached to a Probe, the receiver effectively becomes part of the executing * GL program; performance can be affected by the receiver's implementation. * <ul> * <li>Do not store {@link Frame} or {@link Node} references in fields.</li> * <li>Prefer {@code final} fields and (where performance is important) short methods.</li> * <li>If needed, pass along the {@link VirtualFrame} reference from an event notification as far as * possible through code that is expected to be inlined, since this incurs no runtime overhead. When * access to frame data is needed, substitute a more expensive {@linkplain Frame#materialize() * materialized} representation of the frame.</li> * <li>If a receiver calls back to its tool during event handling, and if performance is an issue, * then this should be through a final "callback" field in the instrument, and the called methods * should be minimal.</li> * <li>On the other hand, implementations should prevent Truffle from inlining beyond a reasonable * point with the method annotation {@link TruffleBoundary}.</li> * <li>The implicit "outer" pointer in a non-static inner class is a useful way to implement * callbacks to owner tools.</li> * <li>Primitive-valued return events are boxed for notification, but Truffle will eliminate the * boxing if they are cast back to their primitive values quickly (in particular before crossing any * {@link TruffleBoundary} annotations). * </ul> * <p> * <h4>Allowing for AST cloning:</h4> * <p> * Truffle routinely <em>clones</em> ASTs, which has consequences for receiver implementation. * <ul> * <li>Even though a {@link Probe} is uniquely associated with a particular location in the * executing Guest Language program, execution events at that location will in general be * implemented by different {@link Node} instances, i.e. <em>clones</em> of the originally probed * node.</li> * <li>Because of <em>cloning</em> the {@link Node} supplied with notifications to a particular * receiver will vary, but because they all represent the same GL program location the events should * be treated as equivalent for most purposes.</li> * </ul> * <p> * <h4>Access to execution state:</h4> * <p> * <ul> * <li>Event notification arguments provide primary access to the GL program's execution states: * <ul> * <li>{@link Node}: the concrete node (in one of the AST's clones) from which the event originated. * </li> * <li>{@link VirtualFrame}: the current execution frame. * </ul> * <li>Some global information is available, for example the execution * {@linkplain TruffleRuntime#iterateFrames(FrameInstanceVisitor) stack}.</li> * <li>Additional information needed by a receiver could be stored when created, preferably * {@code final} of course. For example, a reference to the {@link Probe} to which the receiver's * Instrument has been attached would give access to its corresponding * {@linkplain Probe#getProbedSourceSection() source location} or to the collection of * {@linkplain SyntaxTag tags} currently applied to the Probe.</li> * </ul> * <p> * <h4>Activating and deactivating Instruments:</h4> * <p> * Instruments are <em>single-use</em>: * <ul> * <li>An instrument becomes active only when <em>attached</em> to a Probe via * {@link Probe#attach(Instrument)}, and it may only be attached to a single Probe. It is a runtime * error to attempt attaching a previously attached instrument.</li> * <li>Attaching an instrument modifies every existing clone of the AST to which it is being * attached, which can trigger deoptimization.</li> * <li>The method {@link Instrument#dispose()} makes an instrument inactive by removing it from the * Probe to which it was attached and rendering it permanently inert.</li> * <li>Disposal removes the implementation of an instrument from all ASTs to which it was attached, * which can trigger deoptimization.</li> * </ul> * <p> * <h4>Sharing receivers:</h4> * <p> * Although an Instrument may only be attached to a single Probe, a receiver can be shared among * multiple Instruments. This can be useful for observing events that might happen at different * locations in a single AST, for example all assignments to a particular variable. In this case a * new Instrument would be created and attached at each assignment node, but all the Instruments * would be created with the same receiver. * <p> * <strong>Disclaimer:</strong> experimental; under development. * * @see Probe * @see TruffleEventReceiver */ public final class Instrument { /** * Creates an instrument that will route execution events to a receiver. * * @param receiver a receiver for event generated by the instrument * @param instrumentInfo optional description of the instrument's role * @return a new instrument, ready for attachment at a probe */ public static Instrument create(TruffleEventReceiver receiver, String instrumentInfo) { return new Instrument(receiver, instrumentInfo); } /** * Creates an instrument that will route execution events to a receiver. */ public static Instrument create(TruffleEventReceiver receiver) { return new Instrument(receiver, null); } /** * Tool-supplied receiver of events. */ private final TruffleEventReceiver toolEventreceiver; /** * Optional documentation, mainly for debugging. */ private final String instrumentInfo; /** * Has this instrument been disposed? stays true once set. */ private boolean isDisposed = false; private Probe probe = null; private Instrument(TruffleEventReceiver receiver, String instrumentInfo) { this.toolEventreceiver = receiver; this.instrumentInfo = instrumentInfo; } /** * Removes this instrument (and any clones) from the probe to which it attached and renders the * instrument inert. * * @throws IllegalStateException if this instrument has already been disposed */ public void dispose() throws IllegalStateException { if (isDisposed) { throw new IllegalStateException("Attempt to dispose an already disposed Instrumennt"); } if (probe != null) { // It's attached probe.disposeInstrument(this); } this.isDisposed = true; } Probe getProbe() { return probe; } void setAttachedTo(Probe probe) { this.probe = probe; } /** * Has this instrument been disposed and rendered unusable? */ boolean isDisposed() { return isDisposed; } InstrumentNode addToChain(InstrumentNode nextNode) { return new InstrumentNode(nextNode); } /** * Removes this instrument from an instrument chain. */ InstrumentNode removeFromChain(InstrumentNode instrumentNode) { boolean found = false; if (instrumentNode != null) { if (instrumentNode.getInstrument() == this) { // Found the match at the head of the chain return instrumentNode.nextInstrument; } // Match not at the head of the chain; remove it. found = instrumentNode.removeFromChain(Instrument.this); } if (!found) { throw new IllegalStateException("Couldn't find instrument node to remove: " + this); } return instrumentNode; } @NodeInfo(cost = NodeCost.NONE) final class InstrumentNode extends Node implements TruffleEventReceiver, InstrumentationNode { @Child private InstrumentNode nextInstrument; private InstrumentNode(InstrumentNode nextNode) { this.nextInstrument = nextNode; } /** * Gets the instrument that created this node. */ private Instrument getInstrument() { return Instrument.this; } /** * Removes the node from this chain that was added by a particular instrument, assuming that * the head of the chain is not the one to be replaced. This is awkward, but is required * because {@link Node#replace(Node)} won't take a {@code null} argument. This doesn't work * for the tail of the list, which would be replacing itself with null. So the replacement * must be directed the parent of the node being removed. */ private boolean removeFromChain(Instrument instrument) { assert getInstrument() != instrument; if (nextInstrument == null) { return false; } if (nextInstrument.getInstrument() == instrument) { // Next is the one to remove if (nextInstrument.nextInstrument == null) { // Next is at the tail; just forget nextInstrument = null; } else { // Replace next with its successor nextInstrument.replace(nextInstrument.nextInstrument); } return true; } return nextInstrument.removeFromChain(instrument); } public void enter(Node node, VirtualFrame frame) { Instrument.this.toolEventreceiver.enter(node, frame); if (nextInstrument != null) { nextInstrument.enter(node, frame); } } public void returnVoid(Node node, VirtualFrame frame) { Instrument.this.toolEventreceiver.returnVoid(node, frame); if (nextInstrument != null) { nextInstrument.returnVoid(node, frame); } } public void returnValue(Node node, VirtualFrame frame, Object result) { Instrument.this.toolEventreceiver.returnValue(node, frame, result); if (nextInstrument != null) { nextInstrument.returnValue(node, frame, result); } } public void returnExceptional(Node node, VirtualFrame frame, Exception exception) { Instrument.this.toolEventreceiver.returnExceptional(node, frame, exception); if (nextInstrument != null) { nextInstrument.returnExceptional(node, frame, exception); } } public String instrumentationInfo() { if (Instrument.this.instrumentInfo != null) { return Instrument.this.instrumentInfo; } return toolEventreceiver.getClass().getSimpleName(); } } }