/*

 * Copyright (c) 2012, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.hotspot.stubs;

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

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

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

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

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

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage;

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

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.ParameterNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.StructuredGraph.GuardsStage;

import org.graalvm.compiler.nodes.spi.LoweringTool;

import org.graalvm.compiler.options.OptionValues;

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

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

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

import org.graalvm.compiler.replacements.SnippetTemplate;

import org.graalvm.compiler.replacements.Snippets;

import jdk.vm.ci.meta.Local;

import jdk.vm.ci.meta.LocalVariableTable;

import jdk.vm.ci.meta.ResolvedJavaMethod;

/**

 * Base class for a stub defined by a snippet.

 */

public abstract class SnippetStub extends Stub implements Snippets {

    protected final ResolvedJavaMethod method;

    /**

     * Creates a new snippet stub.

     *

     * @param snippetMethodName name of the single {@link Snippet} annotated method in the class of

     *            this object

     * @param linkage linkage details for a call to the stub

     */

    public SnippetStub(String snippetMethodName, OptionValues options, HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {

        this(null, snippetMethodName, options, providers, linkage);

    }

    /**

     * Creates a new snippet stub.

     *

     * @param snippetDeclaringClass this class in which the {@link Snippet} annotated method is

     *            declared. If {@code null}, this the class of this object is used.

     * @param snippetMethodName name of the single {@link Snippet} annotated method in

     *            {@code snippetDeclaringClass}

     * @param linkage linkage details for a call to the stub

     */

    public SnippetStub(Class<? extends Snippets> snippetDeclaringClass, String snippetMethodName, OptionValues options, HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {

        super(options, providers, linkage);

        this.method = SnippetTemplate.AbstractTemplates.findMethod(providers.getMetaAccess(), snippetDeclaringClass == null ? getClass() : snippetDeclaringClass, snippetMethodName);

        registerSnippet();

    }

    protected void registerSnippet() {

        providers.getReplacements().registerSnippet(method, null, null, false, options);

    }

    @Override

    @SuppressWarnings("try")

    protected StructuredGraph getGraph(DebugContext debug, CompilationIdentifier compilationId) {

        // Stubs cannot have optimistic assumptions since they have

        // to be valid for the entire run of the VM.

        final StructuredGraph graph = buildInitialGraph(debug, compilationId, makeConstArgs());

        try (DebugContext.Scope outer = debug.scope("SnippetStub", graph)) {

            for (ParameterNode param : graph.getNodes(ParameterNode.TYPE)) {

                int index = param.index();

                if (method.getParameterAnnotation(NonNullParameter.class, index) != null) {

                    param.setStamp(param.stamp(NodeView.DEFAULT).join(StampFactory.objectNonNull()));

                }

            }

            new RemoveValueProxyPhase().apply(graph);

            graph.setGuardsStage(GuardsStage.FLOATING_GUARDS);

            CanonicalizerPhase canonicalizer = new CanonicalizerPhase();

            canonicalizer.apply(graph, providers);

            new LoweringPhase(canonicalizer, LoweringTool.StandardLoweringStage.HIGH_TIER).apply(graph, providers);

        } catch (Throwable e) {

            throw debug.handle(e);

        }

        return graph;

    }

    protected StructuredGraph buildInitialGraph(DebugContext debug, CompilationIdentifier compilationId, Object[] args) {

        return providers.getReplacements().getSnippet(method, null, args, false, null, options).copyWithIdentifier(compilationId, debug);

    }

    protected boolean checkConstArg(int index, String expectedName) {

        assert method.getParameterAnnotation(ConstantParameter.class, index) != null : String.format("parameter %d of %s is expected to be constant", index, method.format("%H.%n(%p)"));

        LocalVariableTable lvt = method.getLocalVariableTable();

        if (lvt != null) {

            Local local = lvt.getLocal(index, 0);

            assert local != null;

            String actualName = local.getName();

            assert actualName.equals(expectedName) : String.format("parameter %d of %s is expected to be named %s, not %s", index, method.format("%H.%n(%p)"), expectedName, actualName);

        }

        return true;

    }

    protected Object[] makeConstArgs() {

        int count = method.getSignature().getParameterCount(false);

        Object[] args = new Object[count];

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

            if (method.getParameterAnnotation(ConstantParameter.class, i) != null) {

                args[i] = getConstantParameterValue(i, null);

            }

        }

        return args;

    }

    protected Object getConstantParameterValue(int index, String name) {

        throw new GraalError("%s must override getConstantParameterValue() to provide a value for parameter %d%s", getClass().getName(), index, name == null ? "" : " (" + name + ")");

    }

    @Override

    protected Object debugScopeContext() {

        return getInstalledCodeOwner();

    }

    @Override

    public ResolvedJavaMethod getInstalledCodeOwner() {

        return method;

    }

    @Override

    public String toString() {

        return "Stub<" + getInstalledCodeOwner().format("%h.%n") + ">";

    }

    public ResolvedJavaMethod getMethod() {

        return method;

    }

}