Mercurial > hg > graal-compiler
view graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/java/ExceptionObjectNode.java @ 10006:0478f70900de
extra javadoc for intricacies involved in lowering ExceptionObjectNode
author | Doug Simon <doug.simon@oracle.com> |
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date | Wed, 12 Jun 2013 13:58:01 +0200 |
parents | b4f12c603be5 |
children | ae6f0c381087 |
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/* * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.graal.nodes.java; import static com.oracle.graal.api.meta.LocationIdentity.*; import com.oracle.graal.api.code.*; import com.oracle.graal.api.meta.*; import com.oracle.graal.nodes.*; import com.oracle.graal.nodes.extended.*; import com.oracle.graal.nodes.spi.*; import com.oracle.graal.nodes.type.*; /** * The entry to an exception handler with the exception coming from a call (as opposed to a local * throw instruction or implicit exception). */ public class ExceptionObjectNode extends DispatchBeginNode implements Lowerable, MemoryCheckpoint { public ExceptionObjectNode(MetaAccessProvider runtime) { super(StampFactory.declaredNonNull(runtime.lookupJavaType(Throwable.class))); } @Override public LocationIdentity[] getLocationIdentities() { return new LocationIdentity[]{ANY_LOCATION}; } @Override public void simplify(SimplifierTool tool) { // } private boolean isLowered() { return (stamp() == StampFactory.forVoid()); } /** * The frame state upon entry to an exception handler is such that it is a * {@link BytecodeFrame#rethrowException rethrow exception} state and the stack contains exactly * the exception object (per the JVM spec) to rethrow. This means that the code creating this * state (i.e. the {@link LoadExceptionObjectNode}) cannot cause a deoptimization as the * runtime/interpreter would not have a valid location for the exception object to be rethrown. */ @Override public void lower(LoweringTool tool, LoweringType loweringType) { if (isLowered()) { return; } LoadExceptionObjectNode loadException = graph().add(new LoadExceptionObjectNode(stamp())); loadException.setStateAfter(stateAfter()); replaceAtUsages(loadException); graph().addAfterFixed(this, loadException); tool.setLastFixedNode(loadException); setStateAfter(null); setStamp(StampFactory.forVoid()); } @Override public boolean verify() { if (isLowered()) { return true; } assertTrue(stateAfter() != null || stamp() == StampFactory.forVoid(), "an exception handler needs a frame state"); return super.verify(); } }