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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

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 * 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 jdk.vm.ci.hotspot.HotSpotCallingConventionType.JavaCall;

import static jdk.vm.ci.hotspot.HotSpotCallingConventionType.JavaCallee;

import static jdk.vm.ci.hotspot.HotSpotCallingConventionType.NativeCall;

import static org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage.RegisterEffect.DESTROYS_REGISTERS;

import static org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage.RegisterEffect.PRESERVES_REGISTERS;

import org.graalvm.compiler.core.common.CompilationIdentifier;

import org.graalvm.compiler.core.common.LIRKind;

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

import org.graalvm.compiler.core.common.type.Stamp;

import org.graalvm.compiler.core.common.type.StampFactory;

import org.graalvm.compiler.core.common.type.StampPair;

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.debug.JavaMethodContext;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage.Reexecutability;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage.Transition;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkageImpl;

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

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

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

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.InvokeNode;

import org.graalvm.compiler.nodes.ParameterNode;

import org.graalvm.compiler.nodes.ReturnNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.phases.common.RemoveValueProxyPhase;

import org.graalvm.compiler.replacements.GraphKit;

import org.graalvm.compiler.replacements.nodes.ReadRegisterNode;

import org.graalvm.compiler.word.Word;

import org.graalvm.compiler.word.WordTypes;

import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.hotspot.HotSpotJVMCIRuntime;

import jdk.vm.ci.hotspot.HotSpotSignature;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.JavaMethod;

import jdk.vm.ci.meta.JavaType;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.ResolvedJavaType;

import jdk.vm.ci.meta.Signature;

/**

 * A {@linkplain #getGraph generated} stub for a {@link Transition non-leaf} foreign call from

 * compiled code. A stub is required for such calls as the caller may be scheduled for

 * deoptimization while the call is in progress. And since these are foreign/runtime calls on slow

 * paths, we don't want to force the register allocator to spill around the call. As such, this stub

 * saves and restores all allocatable registers. It also

 * {@linkplain StubUtil#handlePendingException(Word, boolean, boolean) handles} any exceptions

 * raised during the foreign call.

 */

public class ForeignCallStub extends Stub {

    private final HotSpotJVMCIRuntime jvmciRuntime;

    /**

     * The target of the call.

     */

    private final HotSpotForeignCallLinkage target;

    /**

     * Specifies if the JavaThread value for the current thread is to be prepended to the arguments

     * for the call to {@link #target}.

     */

    protected final boolean prependThread;

    /**

     * Creates a stub for a call to code at a given address.

     *

     * @param address the address of the code to call

     * @param descriptor the signature of the call to this stub

     * @param prependThread true if the JavaThread value for the current thread is to be prepended

     *            to the arguments for the call to {@code address}

     * @param reexecutability specifies if the stub call can be re-executed without (meaningful)

     *            side effects. Deoptimization will not return to a point before a stub call that

     *            cannot be re-executed.

     * @param killedLocations the memory locations killed by the stub call

     */

    public ForeignCallStub(OptionValues options, HotSpotJVMCIRuntime runtime, HotSpotProviders providers, long address, ForeignCallDescriptor descriptor, boolean prependThread,

                    Transition transition, Reexecutability reexecutability, LocationIdentity... killedLocations) {

        super(options, providers, HotSpotForeignCallLinkageImpl.create(providers.getMetaAccess(), providers.getCodeCache(), providers.getWordTypes(), providers.getForeignCalls(), descriptor, 0L,

                        PRESERVES_REGISTERS, JavaCall, JavaCallee, transition, reexecutability, killedLocations));

        this.jvmciRuntime = runtime;

        this.prependThread = prependThread;

        Class<?>[] targetParameterTypes = createTargetParameters(descriptor);

        ForeignCallDescriptor targetSig = new ForeignCallDescriptor(descriptor.getName() + ":C", descriptor.getResultType(), targetParameterTypes);

        target = HotSpotForeignCallLinkageImpl.create(providers.getMetaAccess(), providers.getCodeCache(), providers.getWordTypes(), providers.getForeignCalls(), targetSig, address,

                        DESTROYS_REGISTERS, NativeCall, NativeCall, transition, reexecutability, killedLocations);

    }

    /**

     * Gets the linkage information for the call from this stub.

     */

    public HotSpotForeignCallLinkage getTargetLinkage() {

        return target;

    }

    private Class<?>[] createTargetParameters(ForeignCallDescriptor descriptor) {

        Class<?>[] parameters = descriptor.getArgumentTypes();

        if (prependThread) {

            Class<?>[] newParameters = new Class<?>[parameters.length + 1];

            System.arraycopy(parameters, 0, newParameters, 1, parameters.length);

            newParameters[0] = Word.class;

            return newParameters;

        }

        return parameters;

    }

    @Override

    protected ResolvedJavaMethod getInstalledCodeOwner() {

        return null;

    }

    private class DebugScopeContext implements JavaMethod, JavaMethodContext {

        @Override

        public JavaMethod asJavaMethod() {

            return this;

        }

        @Override

        public Signature getSignature() {

            ForeignCallDescriptor d = linkage.getDescriptor();

            MetaAccessProvider metaAccess = providers.getMetaAccess();

            Class<?>[] arguments = d.getArgumentTypes();

            ResolvedJavaType[] parameters = new ResolvedJavaType[arguments.length];

            for (int i = 0; i < arguments.length; i++) {

                parameters[i] = metaAccess.lookupJavaType(arguments[i]);

            }

            return new HotSpotSignature(jvmciRuntime, metaAccess.lookupJavaType(d.getResultType()), parameters);

        }

        @Override

        public String getName() {

            return linkage.getDescriptor().getName();

        }

        @Override

        public JavaType getDeclaringClass() {

            return providers.getMetaAccess().lookupJavaType(ForeignCallStub.class);

        }

        @Override

        public String toString() {

            return format("ForeignCallStub<%n(%p)>");

        }

    }

    @Override

    protected Object debugScopeContext() {

        return new DebugScopeContext() {

        };

    }

    /**

     * Creates a graph for this stub.

     * <p>

     * If the stub returns an object, the graph created corresponds to this pseudo code:

     *

     * <pre>

     *     Object foreignFunctionStub(args...) {

     *         foreignFunction(currentThread,  args);

     *         if ((shouldClearException && clearPendingException(thread())) || (!shouldClearException && hasPendingException(thread)) {

     *             getAndClearObjectResult(thread());

     *             DeoptimizeCallerNode.deopt(None, RuntimeConstraint);

     *         }

     *         return verifyObject(getAndClearObjectResult(thread()));

     *     }

     * </pre>

     *

     * If the stub returns a primitive or word, the graph created corresponds to this pseudo code

     * (using {@code int} as the primitive return type):

     *

     * <pre>

     *     int foreignFunctionStub(args...) {

     *         int result = foreignFunction(currentThread,  args);

     *         if ((shouldClearException && clearPendingException(thread())) || (!shouldClearException && hasPendingException(thread)) {

     *             DeoptimizeCallerNode.deopt(None, RuntimeConstraint);

     *         }

     *         return result;

     *     }

     * </pre>

     *

     * If the stub is void, the graph created corresponds to this pseudo code:

     *

     * <pre>

     *     void foreignFunctionStub(args...) {

     *         foreignFunction(currentThread,  args);

     *         if ((shouldClearException && clearPendingException(thread())) || (!shouldClearException && hasPendingException(thread)) {

     *             DeoptimizeCallerNode.deopt(None, RuntimeConstraint);

     *         }

     *     }

     * </pre>

     *

     * In each example above, the {@code currentThread} argument is the C++ JavaThread value (i.e.,

     * %r15 on AMD64) and is only prepended if {@link #prependThread} is true.

     */

    @Override

    @SuppressWarnings("try")

    protected StructuredGraph getGraph(DebugContext debug, CompilationIdentifier compilationId) {

        WordTypes wordTypes = providers.getWordTypes();

        Class<?>[] args = linkage.getDescriptor().getArgumentTypes();

        boolean isObjectResult = !LIRKind.isValue(linkage.getOutgoingCallingConvention().getReturn());

        // Do we want to clear the pending exception?

        boolean shouldClearException = linkage.isReexecutable() || linkage.isReexecutableOnlyAfterException();

        try {

            ResolvedJavaMethod thisMethod = providers.getMetaAccess().lookupJavaMethod(ForeignCallStub.class.getDeclaredMethod("getGraph", DebugContext.class, CompilationIdentifier.class));

            GraphKit kit = new GraphKit(debug, thisMethod, providers, wordTypes, providers.getGraphBuilderPlugins(), compilationId, toString());

            StructuredGraph graph = kit.getGraph();

            ParameterNode[] params = createParameters(kit, args);

            ReadRegisterNode thread = kit.append(new ReadRegisterNode(providers.getRegisters().getThreadRegister(), wordTypes.getWordKind(), true, false));

            ValueNode result = createTargetCall(kit, params, thread);

            kit.createInvoke(StubUtil.class, "handlePendingException", thread, ConstantNode.forBoolean(shouldClearException, graph), ConstantNode.forBoolean(isObjectResult, graph));

            if (isObjectResult) {

                InvokeNode object = kit.createInvoke(HotSpotReplacementsUtil.class, "getAndClearObjectResult", thread);

                result = kit.createInvoke(StubUtil.class, "verifyObject", object);

            }

            kit.append(new ReturnNode(linkage.getDescriptor().getResultType() == void.class ? null : result));

            debug.dump(DebugContext.VERBOSE_LEVEL, graph, "Initial stub graph");

            kit.inlineInvokes("Foreign call stub.", "Backend");

            new RemoveValueProxyPhase().apply(graph);

            debug.dump(DebugContext.VERBOSE_LEVEL, graph, "Stub graph before compilation");

            return graph;

        } catch (Exception e) {

            throw GraalError.shouldNotReachHere(e);

        }

    }

    private ParameterNode[] createParameters(GraphKit kit, Class<?>[] args) {

        ParameterNode[] params = new ParameterNode[args.length];

        ResolvedJavaType accessingClass = providers.getMetaAccess().lookupJavaType(getClass());

        for (int i = 0; i < args.length; i++) {

            ResolvedJavaType type = providers.getMetaAccess().lookupJavaType(args[i]).resolve(accessingClass);

            StampPair stamp = StampFactory.forDeclaredType(kit.getGraph().getAssumptions(), type, false);

            ParameterNode param = kit.unique(new ParameterNode(i, stamp));

            params[i] = param;

        }

        return params;

    }

    private StubForeignCallNode createTargetCall(GraphKit kit, ParameterNode[] params, ReadRegisterNode thread) {

        Stamp stamp = StampFactory.forKind(JavaKind.fromJavaClass(target.getDescriptor().getResultType()));

        if (prependThread) {

            ValueNode[] targetArguments = new ValueNode[1 + params.length];

            targetArguments[0] = thread;

            System.arraycopy(params, 0, targetArguments, 1, params.length);

            return kit.append(new StubForeignCallNode(providers.getForeignCalls(), stamp, target.getDescriptor(), targetArguments));

        } else {

            return kit.append(new StubForeignCallNode(providers.getForeignCalls(), stamp, target.getDescriptor(), params));

        }

    }

}