/*

 * Copyright (c) 2014, 2018, 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.core.test;

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.nodes.ReturnNode;

import org.graalvm.compiler.nodes.StructuredGraph;

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

import org.junit.Ignore;

import org.junit.Test;

import jdk.vm.ci.meta.Assumptions.AssumptionResult;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * This test illustrates problems and limitations with class hierarchy analysis when default methods

 * are involved.

 */

public class FindUniqueDefaultMethodTest extends GraalCompilerTest {

    interface Interface1 {

        default int v1() {

            return 1;

        }

    }

    static class Implementor1 implements Interface1 {

        int callV1() {

            return v1();

        }

    }

    static class Subclass1 extends Implementor1 {

    }

    /**

     * HotSpot has an internal mismatch with CHA and default methods. The initial query says that

     * it's a unique method but the verification code that ensures that a dependence of this kind

     * would pass will fail an assert in debug mode.

     */

    @Test

    public void testFindUnique() {

        ResolvedJavaType cType = getMetaAccess().lookupJavaType(Implementor1.class);

        cType.initialize();

        ResolvedJavaMethod v1Method = getMetaAccess().lookupJavaMethod(this.getMethod(Interface1.class, "v1"));

        AssumptionResult<ResolvedJavaMethod> method = cType.findUniqueConcreteMethod(v1Method);

        assertDeepEquals(null, method);

    }

    interface Interface2 {

        default int v1() {

            return 1;

        }

    }

    static class Base2 {

        public int v2() {

            return 1;

        }

    }

    static class Implementor2 extends Base2 implements Interface2 {

        int callV1() {

            return v1();

        }

        int callV2() {

            return v2();

        }

    }

    static class Subclass2 extends Implementor2 {

    }

    /**

     * This test illustrates a common pattern where a method at the root of a hierarchy is the only

     * implementation and can be statically inlined.

     */

    @SuppressWarnings("unused")

    @Test

    public void testInherited() {

        Subclass2 s = new Subclass2();

        testConstantReturn("runInherited", 1);

    }

    /**

     * Test same pattern as above but using default methods instead. HotSpot doesn't allow this

     * version to be optimized.

     */

    @SuppressWarnings("unused")

    @Test

    @Ignore("HotSpot CHA doesn't treat default methods like regular methods")

    public void testDefault() {

        Subclass2 s = new Subclass2();

        testConstantReturn("runDefault", 1);

    }

    public int runDefault(Implementor2 i) {

        return i.callV1();

    }

    public int runInherited(Implementor2 i) {

        return i.callV2();

    }

    private void testConstantReturn(String name, Object value) {

        StructuredGraph result = buildGraph(name);

        ReturnNode ret = result.getNodes(ReturnNode.TYPE).first();

        assertDeepEquals(1, result.getNodes(ReturnNode.TYPE).count());

        assertDeepEquals(true, ret.result().isConstant());

        assertDeepEquals(value, ret.result().asJavaConstant().asBoxedPrimitive());

    }

    @SuppressWarnings("try")

    protected StructuredGraph buildGraph(final String snippet) {

        DebugContext debug = getDebugContext();

        try (DebugContext.Scope s = debug.scope("InstanceOfTest", getMetaAccess().lookupJavaMethod(getMethod(snippet)))) {

            StructuredGraph graph = parseEager(snippet, AllowAssumptions.YES, debug);

            compile(graph.method(), graph);

            debug.dump(DebugContext.BASIC_LEVEL, graph, snippet);

            return graph;

        } catch (Throwable e) {

            throw debug.handle(e);

        }

    }

}