JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2009, 2019, 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
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 */


package org.graalvm.compiler.nodes.java;

import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.MetaAccessProvider;

import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.core.common.type.TypeReference;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.nodeinfo.InputType;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.AbstractBeginNode;
import org.graalvm.compiler.nodes.BeginStateSplitNode;
import org.graalvm.compiler.nodes.InvokeWithExceptionNode;
import org.graalvm.compiler.nodes.KillingBeginNode;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
import org.graalvm.compiler.nodes.spi.Lowerable;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import jdk.internal.vm.compiler.word.LocationIdentity;

import static org.graalvm.compiler.nodeinfo.InputType.Memory;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_8;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_8;

/**
 * The entry to an exception handler with the exception coming from a call (as opposed to a local
 * throw instruction or implicit exception).
 */
@NodeInfo(allowedUsageTypes = Memory, cycles = CYCLES_8, size = SIZE_8)
public final class ExceptionObjectNode extends BeginStateSplitNode implements Lowerable, MemoryCheckpoint.Single {
    public static final NodeClass<ExceptionObjectNode> TYPE = NodeClass.create(ExceptionObjectNode.class);

    public ExceptionObjectNode(MetaAccessProvider metaAccess) {
        super(TYPE, StampFactory.objectNonNull(TypeReference.createTrustedWithoutAssumptions(metaAccess.lookupJavaType(Throwable.class))));
    }

    @Override
    public LocationIdentity getKilledLocationIdentity() {
        return LocationIdentity.any();
    }

    /**
     * An exception handler is an entry point to a method from the runtime and so represents an
     * instruction that cannot be re-executed. It therefore needs a frame state.
     */
    @Override
    public boolean hasSideEffect() {
        return true;
    }

    @Override
    public void lower(LoweringTool tool) {
        if (graph().getGuardsStage() == StructuredGraph.GuardsStage.FIXED_DEOPTS) {
            /*
             * Now the lowering to BeginNode+LoadExceptionNode can be performed, since no more
             * deopts can float in between the begin node and the load exception node.
             */
            LocationIdentity locationsKilledByInvoke = ((InvokeWithExceptionNode) predecessor()).getKilledLocationIdentity();
            AbstractBeginNode entry = graph().add(KillingBeginNode.create(locationsKilledByInvoke));
            LoadExceptionObjectNode loadException = graph().add(new LoadExceptionObjectNode(stamp(NodeView.DEFAULT)));

            loadException.setStateAfter(stateAfter());
            replaceAtUsages(InputType.Value, loadException);
            graph().replaceFixedWithFixed(this, entry);
            entry.graph().addAfterFixed(entry, loadException);


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