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 *

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package org.graalvm.compiler.api.directives.test;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

import org.junit.Assert;

import org.junit.Test;

import org.graalvm.compiler.api.directives.GraalDirectives;

import org.graalvm.compiler.core.test.GraalCompilerTest;

import org.graalvm.compiler.nodes.ParameterNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.phases.OptimisticOptimizations;

import org.graalvm.compiler.phases.OptimisticOptimizations.Optimization;

import org.graalvm.compiler.phases.tiers.HighTierContext;

/**

 * Tests for {@link GraalDirectives#blackhole}.

 *

 * There are two snippets for each kind:

 * <ul>

 * <li>blackhole&lt;Kind&gt;Snippet verifies that dead code elimination is prevented by the

 * blackhole directive.

 * <li>&lt;kind&gt;Snippet verifies that dead code elimination does happen if the blackhole

 * directive is not there.

 * </ul>

 *

 */

public class BlackholeDirectiveTest extends GraalCompilerTest {

    @Retention(RetentionPolicy.RUNTIME)

    @Target(ElementType.METHOD)

    private @interface BlackholeSnippet {

        boolean expectParameterUsage();

    }

    @BlackholeSnippet(expectParameterUsage = false)

    public static int booleanSnippet(int arg) {

        boolean b = arg > 3;

        if (b) {

            return 1;

        } else {

            return 1;

        }

    }

    @BlackholeSnippet(expectParameterUsage = true)

    public static int blackholeBooleanSnippet(int arg) {

        boolean b = arg > 3;

        GraalDirectives.blackhole(b);

        if (b) {

            return 1;

        } else {

            return 1;

        }

    }

    @Test

    public void testBoolean() {

        test("booleanSnippet", 5);

        test("blackholeBooleanSnippet", 5);

    }

    @BlackholeSnippet(expectParameterUsage = false)

    public static int intSnippet(int arg) {

        int x = 42 + arg;

        return x - arg;

    }

    @BlackholeSnippet(expectParameterUsage = true)

    public static int blackholeIntSnippet(int arg) {

        int x = 42 + arg;

        GraalDirectives.blackhole(x);

        return x - arg;

    }

    @Test

    public void testInt() {

        test("intSnippet", 17);

        test("blackholeIntSnippet", 17);

    }

    private static class Dummy {

        private int x = 42;

    }

    @BlackholeSnippet(expectParameterUsage = false)

    public static int objectSnippet(int arg) {

        Dummy obj = new Dummy();

        int ret = obj.x;

        obj.x = arg;

        return ret;

    }

    @BlackholeSnippet(expectParameterUsage = true)

    public static int blackholeObjectSnippet(int arg) {

        Dummy obj = new Dummy();

        int ret = obj.x;

        obj.x = arg;

        GraalDirectives.blackhole(obj);

        return ret;

    }

    @Test

    public void testObject() {

        test("objectSnippet", 37);

        test("blackholeObjectSnippet", 37);

    }

    @Override

    protected HighTierContext getDefaultHighTierContext() {

        return new HighTierContext(getProviders(), getDefaultGraphBuilderSuite(), OptimisticOptimizations.ALL.remove(Optimization.RemoveNeverExecutedCode));

    }

    @Override

    protected void checkLowTierGraph(StructuredGraph graph) {

        BlackholeSnippet snippet = graph.method().getAnnotation(BlackholeSnippet.class);

        ParameterNode arg = graph.getParameter(0);

        if (snippet.expectParameterUsage()) {

            Assert.assertNotNull("couldn't find ParameterNode(0)", arg);

            Assert.assertFalse("expected usages of " + arg, arg.hasNoUsages());

        } else {

            Assert.assertTrue("expected no usages of ParameterNode", arg == null || arg.hasNoUsages());

        }

    }

}