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 * Copyright (c) 2012, 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.

 *

 * 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.hotspot.stubs;

import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_VMCONFIG;

import static org.graalvm.compiler.hotspot.nodes.JumpToExceptionHandlerNode.jumpToExceptionHandler;

import static org.graalvm.compiler.hotspot.nodes.PatchReturnAddressNode.patchReturnAddress;

import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.readExceptionOop;

import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.readExceptionPc;

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.stubs.StubUtil.cAssertionsEnabled;

import static org.graalvm.compiler.hotspot.stubs.StubUtil.decipher;

import static org.graalvm.compiler.hotspot.stubs.StubUtil.fatal;

import static org.graalvm.compiler.hotspot.stubs.StubUtil.newDescriptor;

import static org.graalvm.compiler.hotspot.stubs.StubUtil.printf;

import org.graalvm.compiler.api.replacements.Fold;

import org.graalvm.compiler.api.replacements.Fold.InjectedParameter;

import org.graalvm.compiler.api.replacements.Snippet;

import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;

import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;

import org.graalvm.compiler.debug.Assertions;

import org.graalvm.compiler.graph.Node.ConstantNodeParameter;

import org.graalvm.compiler.graph.Node.NodeIntrinsic;

import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;

import org.graalvm.compiler.hotspot.HotSpotBackend;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage;

import org.graalvm.compiler.hotspot.meta.HotSpotProviders;

import org.graalvm.compiler.hotspot.nodes.StubForeignCallNode;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.word.Word;

import org.graalvm.word.WordFactory;

import jdk.vm.ci.code.Register;

/**

 * Stub called by the {@linkplain GraalHotSpotVMConfig#MARKID_EXCEPTION_HANDLER_ENTRY exception

 * handler entry point} in a compiled method. This entry point is used when returning to a method to

 * handle an exception thrown by a callee. It is not used for routing implicit exceptions.

 * Therefore, it does not need to save any registers as HotSpot uses a caller save convention.

 * <p>

 * The descriptor for a call to this stub is {@link HotSpotBackend#EXCEPTION_HANDLER}.

 */

public class ExceptionHandlerStub extends SnippetStub {

    public ExceptionHandlerStub(OptionValues options, HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {

        super("exceptionHandler", options, providers, linkage);

    }

    /**

     * This stub is called when returning to a method to handle an exception thrown by a callee. It

     * is not used for routing implicit exceptions. Therefore, it does not need to save any

     * registers as HotSpot uses a caller save convention.

     */

    @Override

    public boolean preservesRegisters() {

        return false;

    }

    @Override

    protected Object getConstantParameterValue(int index, String name) {

        if (index == 2) {

            return providers.getRegisters().getThreadRegister();

        }

        assert index == 3;

        return options;

    }

    @Snippet

    private static void exceptionHandler(Object exception, Word exceptionPc, @ConstantParameter Register threadRegister, @ConstantParameter OptionValues options) {

        Word thread = registerAsWord(threadRegister);

        checkNoExceptionInThread(thread, assertionsEnabled(INJECTED_VMCONFIG));

        checkExceptionNotNull(assertionsEnabled(INJECTED_VMCONFIG), exception);

        writeExceptionOop(thread, exception);

        writeExceptionPc(thread, exceptionPc);

        if (logging(options)) {

            printf("handling exception %p (", Word.objectToTrackedPointer(exception).rawValue());

            decipher(Word.objectToTrackedPointer(exception).rawValue());

            printf(") at %p (", exceptionPc.rawValue());

            decipher(exceptionPc.rawValue());

            printf(")\n");

        }

        // patch throwing pc into return address so that deoptimization finds the right debug info

        patchReturnAddress(exceptionPc);

        Word handlerPc = exceptionHandlerForPc(EXCEPTION_HANDLER_FOR_PC, thread);

        if (logging(options)) {

            printf("handler for exception %p at %p is at %p (", Word.objectToTrackedPointer(exception).rawValue(), exceptionPc.rawValue(), handlerPc.rawValue());

            decipher(handlerPc.rawValue());

            printf(")\n");

        }

        // patch the return address so that this stub returns to the exception handler

        jumpToExceptionHandler(handlerPc);

    }

    static void checkNoExceptionInThread(Word thread, boolean enabled) {

        if (enabled) {

            Object currentException = readExceptionOop(thread);

            if (currentException != null) {

                fatal("exception object in thread must be null, not %p", Word.objectToTrackedPointer(currentException).rawValue());

            }

            if (cAssertionsEnabled(INJECTED_VMCONFIG)) {

                // This thread-local is only cleared in DEBUG builds of the VM

                // (see OptoRuntime::generate_exception_blob)

                Word currentExceptionPc = readExceptionPc(thread);

                if (currentExceptionPc.notEqual(WordFactory.zero())) {

                    fatal("exception PC in thread must be zero, not %p", currentExceptionPc.rawValue());

                }

            }

        }

    }

    static void checkExceptionNotNull(boolean enabled, Object exception) {

        if (enabled && exception == null) {

            fatal("exception must not be null");

        }

    }

    @Fold

    static boolean logging(OptionValues options) {

        return StubOptions.TraceExceptionHandlerStub.getValue(options);

    }

    /**

     * Determines if either Java assertions are enabled for Graal or if this is a HotSpot build

     * where the ASSERT mechanism is enabled.

     */

    @Fold

    @SuppressWarnings("all")

    static boolean assertionsEnabled(@InjectedParameter GraalHotSpotVMConfig config) {

        return Assertions.assertionsEnabled() || cAssertionsEnabled(config);

    }

    public static final ForeignCallDescriptor EXCEPTION_HANDLER_FOR_PC = newDescriptor(ExceptionHandlerStub.class, "exceptionHandlerForPc", Word.class, Word.class);

    @NodeIntrinsic(value = StubForeignCallNode.class)

    public static native Word exceptionHandlerForPc(@ConstantNodeParameter ForeignCallDescriptor exceptionHandlerForPc, Word thread);

}