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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package org.graalvm.compiler.hotspot.replacements;

import static org.graalvm.compiler.hotspot.meta.HotSpotForeignCallsProviderImpl.LOAD_AND_CLEAR_EXCEPTION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.EXCEPTION_OOP_LOCATION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.EXCEPTION_PC_LOCATION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.readExceptionOop;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.registerAsWord;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.writeExceptionOop;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.writeExceptionPc;
import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.LoadExceptionObjectInVM;
import static org.graalvm.compiler.nodes.PiNode.piCastToSnippetReplaceeStamp;
import static org.graalvm.compiler.replacements.SnippetTemplate.DEFAULT_REPLACER;

import org.graalvm.compiler.api.replacements.Snippet;
import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.debug.DebugHandlersFactory;
import org.graalvm.compiler.hotspot.meta.HotSpotProviders;
import org.graalvm.compiler.hotspot.meta.HotSpotRegistersProvider;
import org.graalvm.compiler.hotspot.word.HotSpotWordTypes;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.extended.ForeignCallNode;
import org.graalvm.compiler.nodes.java.LoadExceptionObjectNode;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import org.graalvm.compiler.options.OptionValues;
import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
import org.graalvm.compiler.replacements.SnippetTemplate.SnippetInfo;
import org.graalvm.compiler.replacements.Snippets;
import org.graalvm.compiler.replacements.nodes.ReadRegisterNode;
import org.graalvm.compiler.word.Word;
import jdk.internal.vm.compiler.word.WordFactory;

import jdk.vm.ci.code.BytecodeFrame;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.TargetDescription;
import jdk.vm.ci.meta.ResolvedJavaType;

Snippet for loading the exception object at the start of an exception dispatcher.

The frame state upon entry to an exception handler is such that it is a rethrow exception state and the stack contains exactly the exception object (per the JVM spec) to rethrow. This means that the code generated for this node must not cause a deoptimization as the runtime/interpreter would not have a valid location to find the exception object to be rethrown.

/** * Snippet for loading the exception object at the start of an exception dispatcher. * <p> * 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 generated for this node * must not cause a deoptimization as the runtime/interpreter would not have a valid location to * find the exception object to be rethrown. */
public class LoadExceptionObjectSnippets implements Snippets { @Snippet public static Object loadException(@ConstantParameter Register threadRegister) { Word thread = registerAsWord(threadRegister); Object exception = readExceptionOop(thread); writeExceptionOop(thread, null); writeExceptionPc(thread, WordFactory.zero()); return piCastToSnippetReplaceeStamp(exception); } public static class Templates extends AbstractTemplates { private final SnippetInfo loadException = snippet(LoadExceptionObjectSnippets.class, "loadException", EXCEPTION_OOP_LOCATION, EXCEPTION_PC_LOCATION); private final HotSpotWordTypes wordTypes; public Templates(OptionValues options, Iterable<DebugHandlersFactory> factories, HotSpotProviders providers, TargetDescription target) { super(options, factories, providers, providers.getSnippetReflection(), target); this.wordTypes = providers.getWordTypes(); } public void lower(LoadExceptionObjectNode loadExceptionObject, HotSpotRegistersProvider registers, LoweringTool tool) { StructuredGraph graph = loadExceptionObject.graph(); if (LoadExceptionObjectInVM.getValue(graph.getOptions())) { ResolvedJavaType wordType = providers.getMetaAccess().lookupJavaType(Word.class); Stamp stamp = wordTypes.getWordStamp(wordType); ReadRegisterNode thread = graph.add(new ReadRegisterNode(stamp, registers.getThreadRegister(), true, false)); graph.addBeforeFixed(loadExceptionObject, thread); ForeignCallNode loadExceptionC = graph.add(new ForeignCallNode(providers.getForeignCalls(), LOAD_AND_CLEAR_EXCEPTION, thread)); loadExceptionC.setStateAfter(loadExceptionObject.stateAfter()); graph.replaceFixedWithFixed(loadExceptionObject, loadExceptionC); } else { Arguments args = new Arguments(loadException, loadExceptionObject.graph().getGuardsStage(), tool.getLoweringStage()); args.addConst("threadRegister", registers.getThreadRegister()); template(loadExceptionObject, args).instantiate(providers.getMetaAccess(), loadExceptionObject, DEFAULT_REPLACER, args); } } } }