1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  23 
  24 /*
  25  * @test TestAnonymousClassUnloading
  26  * @bug 8054402
  27  * @summary "Tests unloading of anonymous classes."
  28  * @library /test/lib /
  29  * @modules java.base/jdk.internal.misc
  30  *
  31  * @run main/othervm/bootclasspath -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
  32  *      -XX:-BackgroundCompilation
  33  *      compiler.classUnloading.anonymousClass.TestAnonymousClassUnloading
  34  */
  35 
  36 package compiler.classUnloading.anonymousClass;
  37 
  38 import jdk.internal.misc.Unsafe;
  39 import sun.hotspot.WhiteBox;
  40 
  41 import java.io.IOException;
  42 import java.lang.reflect.Method;
  43 import java.net.URL;
  44 import java.net.URLConnection;
  45 import compiler.whitebox.CompilerWhiteBoxTest;
  46 
  47 public class TestAnonymousClassUnloading {
  48     private static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();
  49     private static final Unsafe UNSAFE = Unsafe.getUnsafe();
  50 
  51     /**
  52      * We override hashCode here to be able to access this implementation
  53      * via an Object reference (we cannot cast to TestAnonymousClassUnloading).
  54      */
  55     @Override
  56     public int hashCode() {
  57         return 42;
  58     }
  59 
  60     /**
  61      * Does some work by using the anonymousClass.
  62      * @param anonymousClass Class performing some work (will be unloaded)
  63      */
  64     static private void doWork(Class<?> anonymousClass) throws InstantiationException, IllegalAccessException {
  65         // Create a new instance
  66         Object anon = anonymousClass.newInstance();
  67         // We would like to call a method of anonymousClass here but we cannot cast because the class
  68         // was loaded by a different class loader. One solution would be to use reflection but since
  69         // we want C2 to implement the call as an IC we call Object::hashCode() here which actually
  70         // calls anonymousClass::hashCode(). C2 will then implement this call as an IC.
  71         if (anon.hashCode() != 42) {
  72             new RuntimeException("Work not done");
  73         }
  74     }
  75 
  76     /**
  77      * Makes sure that method is compiled by forcing compilation if not yet compiled.
  78      * @param m Method to be checked
  79      */
  80     static private void makeSureIsCompiled(Method m) {
  81         // Make sure background compilation is disabled
  82         if (WHITE_BOX.getBooleanVMFlag("BackgroundCompilation")) {
  83             throw new RuntimeException("Background compilation enabled");
  84         }
  85 
  86         // Check if already compiled
  87         if (!WHITE_BOX.isMethodCompiled(m)) {
  88             // If not, try to compile it with C2
  89             if(!WHITE_BOX.enqueueMethodForCompilation(m, CompilerWhiteBoxTest.COMP_LEVEL_FULL_OPTIMIZATION)) {
  90                 // C2 compiler not available, try to compile with C1
  91                 WHITE_BOX.enqueueMethodForCompilation(m, CompilerWhiteBoxTest.COMP_LEVEL_SIMPLE);
  92             }
  93             // Because background compilation is disabled, method should now be compiled
  94             if(!WHITE_BOX.isMethodCompiled(m)) {
  95                 throw new RuntimeException(m + " not compiled");
  96             }
  97         }
  98     }
  99 
 100     /**
 101      * This test creates stale Klass* metadata referenced by a compiled IC.
 102      *
 103      * The following steps are performed:
 104      * (1) An anonymous version of TestAnonymousClassUnloading is loaded by a custom class loader
 105      * (2) The method doWork that calls a method of the anonymous class is compiled. The call
 106      *     is implemented as an IC referencing Klass* metadata of the anonymous class.
 107      * (3) Unloading of the anonymous class is enforced. The IC now references dead metadata.
 108      */
 109     static public void main(String[] args) throws Exception {
 110         // (1) Load an anonymous version of this class using the corresponding Unsafe method
 111         String rn = TestAnonymousClassUnloading.class.getSimpleName() + ".class";
 112         URL classUrl = TestAnonymousClassUnloading.class.getResource(rn);
 113         URLConnection connection = classUrl.openConnection();
 114 
 115         int length = connection.getContentLength();
 116         byte[] classBytes = connection.getInputStream().readAllBytes();
 117         if (length != -1 && classBytes.length != length) {
 118             throw new IOException("Expected:" + length + ", actual: " + classBytes.length);
 119         }
 120 
 121         Class<?> anonymousClass = UNSAFE.defineAnonymousClass(TestAnonymousClassUnloading.class, classBytes, null);
 122 
 123         // (2) Make sure all paths of doWork are profiled and compiled
 124         for (int i = 0; i < 100000; ++i) {
 125             doWork(anonymousClass);
 126         }
 127 
 128         // Make sure doWork is compiled now
 129         Method doWork = TestAnonymousClassUnloading.class.getDeclaredMethod("doWork", Class.class);
 130         makeSureIsCompiled(doWork);
 131 
 132         // (3) Throw away reference to anonymousClass to allow unloading
 133         anonymousClass = null;
 134 
 135         // Force garbage collection to trigger unloading of anonymousClass
 136         // Dead metadata reference to anonymousClass triggers JDK-8054402
 137         WHITE_BOX.fullGC();
 138     }
 139 }