8141551: C2 can not handle returns with inccompatible interface arrays

Reviewed-by: kvn

src/share/vm/opto/cfgnode.cpp

@@ -973,7 +973,7 @@ const Type *PhiNode::Value( PhaseTransform *phase ) const {
 #ifdef ASSERT
   // The following logic has been moved into TypeOopPtr::filter.
   const Type* jt = t->join_speculative(_type);
-  if( jt->empty() ) {           // Emptied out???
+  if (jt->empty()) {           // Emptied out???
 
     // Check for evil case of 't' being a class and '_type' expecting an
     // interface.  This can happen because the bytecodes do not contain
@@ -984,14 +984,21 @@ const Type *PhiNode::Value( PhaseTransform *phase ) const {
     // be 'I' or 'j/l/O'.  Thus we'll pick 'j/l/O'.  If this then flows
     // into a Phi which "knows" it's an Interface type we'll have to
     // uplift the type.
-    if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
-      { assert(ft == _type, ""); } // Uplift to interface
-    else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
-      { assert(ft == _type, ""); } // Uplift to interface
-    // Otherwise it's something stupid like non-overlapping int ranges
-    // found on dying counted loops.
-    else
-      { assert(ft == Type::TOP, ""); } // Canonical empty value
+    if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
+      assert(ft == _type, ""); // Uplift to interface
+    } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
+      assert(ft == _type, ""); // Uplift to interface
+    } else {
+      // We also have to handle 'evil cases' of interface- vs. class-arrays
+      Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
+      if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
+          assert(ft == _type, "");   // Uplift to array of interface
+      } else {
+        // Otherwise it's something stupid like non-overlapping int ranges
+        // found on dying counted loops.
+        assert(ft == Type::TOP, ""); // Canonical empty value
+      }
+    }
   }
 
   else {

src/share/vm/opto/parse1.cpp

@@ -962,13 +962,18 @@ void Parse::do_exits() {
       // In case of concurrent class loading, the type we set for the
       // ret_phi in build_exits() may have been too optimistic and the
       // ret_phi may be top now.
-#ifdef ASSERT
+      // Otherwise, we've encountered an error and have to mark the method as
+      // not compilable. Just using an assertion instead would be dangerous
+      // as this could lead to an infinite compile loop in non-debug builds.
       {
         MutexLockerEx ml(Compile_lock, Mutex::_no_safepoint_check_flag);
-        assert(ret_type->isa_ptr() && C->env()->system_dictionary_modification_counter_changed(), "return value must be well defined");
+        if (C->env()->system_dictionary_modification_counter_changed()) {
+          C->record_failure(C2Compiler::retry_class_loading_during_parsing());
+        } else {
+          C->record_method_not_compilable("Can't determine return type.");
+        }
       }
-#endif
-      C->record_failure(C2Compiler::retry_class_loading_during_parsing());
+      return;
     }
     _exits.push_node(ret_type->basic_type(), ret_phi);
   }
@@ -2093,15 +2098,24 @@ void Parse::return_current(Node* value) {
     // here.
     Node* phi = _exits.argument(0);
     const TypeInstPtr *tr = phi->bottom_type()->isa_instptr();
-    if( tr && tr->klass()->is_loaded() &&
-        tr->klass()->is_interface() ) {
+    if (tr && tr->klass()->is_loaded() &&
+        tr->klass()->is_interface()) {
       const TypeInstPtr *tp = value->bottom_type()->isa_instptr();
       if (tp && tp->klass()->is_loaded() &&
           !tp->klass()->is_interface()) {
         // sharpen the type eagerly; this eases certain assert checking
         if (tp->higher_equal(TypeInstPtr::NOTNULL))
           tr = tr->join_speculative(TypeInstPtr::NOTNULL)->is_instptr();
-        value = _gvn.transform(new (C) CheckCastPPNode(0,value,tr));
+        value = _gvn.transform(new (C) CheckCastPPNode(0, value, tr));
+      }
+    } else {
+      // Also handle returns of oop-arrays to an arrays-of-interface return
+      const TypeInstPtr* phi_tip;
+      const TypeInstPtr* val_tip;
+      Type::get_arrays_base_elements(phi->bottom_type(), value->bottom_type(), &phi_tip, &val_tip);
+      if (phi_tip != NULL && phi_tip->is_loaded() && phi_tip->klass()->is_interface() &&
+          val_tip != NULL && val_tip->is_loaded() && !val_tip->klass()->is_interface()) {
+         value = _gvn.transform(new (C) CheckCastPPNode(0, value, phi->bottom_type()));
       }
     }
     phi->add_req(value);

src/share/vm/opto/type.cpp

@@ -149,6 +149,33 @@ BasicType Type::array_element_basic_type() const {
   return bt;
 }
 
+// For two instance arrays of same dimension, return the base element types.
+// Otherwise or if the arrays have different dimensions, return NULL.
+void Type::get_arrays_base_elements(const Type *a1, const Type *a2,
+                                    const TypeInstPtr **e1, const TypeInstPtr **e2) {
+
+  if (e1) *e1 = NULL;
+  if (e2) *e2 = NULL;
+  const TypeAryPtr* a1tap = (a1 == NULL) ? NULL : a1->isa_aryptr();
+  const TypeAryPtr* a2tap = (a2 == NULL) ? NULL : a2->isa_aryptr();
+
+  if (a1tap != NULL && a2tap != NULL) {
+    // Handle multidimensional arrays
+    const TypePtr* a1tp = a1tap->elem()->make_ptr();
+    const TypePtr* a2tp = a2tap->elem()->make_ptr();
+    while (a1tp && a1tp->isa_aryptr() && a2tp && a2tp->isa_aryptr()) {
+      a1tap = a1tp->is_aryptr();
+      a2tap = a2tp->is_aryptr();
+      a1tp = a1tap->elem()->make_ptr();
+      a2tp = a2tap->elem()->make_ptr();
+    }
+    if (a1tp && a1tp->isa_instptr() && a2tp && a2tp->isa_instptr()) {
+      if (e1) *e1 = a1tp->is_instptr();
+      if (e2) *e2 = a2tp->is_instptr();
+    }
+  }
+}
+
 //---------------------------get_typeflow_type---------------------------------
 // Import a type produced by ciTypeFlow.
 const Type* Type::get_typeflow_type(ciType* type) {
@@ -1982,7 +2009,11 @@ const Type* TypeAry::remove_speculative() const {
 bool TypeAry::interface_vs_oop(const Type *t) const {
   const TypeAry* t_ary = t->is_ary();
   if (t_ary) {
-    return _elem->interface_vs_oop(t_ary->_elem);
+    const TypePtr* this_ptr = _elem->make_ptr(); // In case we have narrow_oops
+    const TypePtr*    t_ptr = t_ary->_elem->make_ptr();
+    if(this_ptr != NULL && t_ptr != NULL) {
+      return this_ptr->interface_vs_oop(t_ptr);
+    }
   }
   return false;
 }
@@ -2834,8 +2865,17 @@ const Type *TypeOopPtr::filter_helper(const Type *kills, bool include_speculativ
     // be 'I' or 'j/l/O'.  Thus we'll pick 'j/l/O'.  If this then flows
     // into a Phi which "knows" it's an Interface type we'll have to
     // uplift the type.
-    if (!empty() && ktip != NULL && ktip->is_loaded() && ktip->klass()->is_interface())
-      return kills;             // Uplift to interface
+    if (!empty()) {
+      if (ktip != NULL && ktip->is_loaded() && ktip->klass()->is_interface()) {
+        return kills;           // Uplift to interface
+      }
+      // Also check for evil cases of 'this' being a class array
+      // and 'kills' expecting an array of interfaces.
+      Type::get_arrays_base_elements(ft, kills, NULL, &ktip);
+      if (ktip != NULL && ktip->is_loaded() && ktip->klass()->is_interface()) {
+        return kills;           // Uplift to array of interface
+      }
+    }
 
     return Type::TOP;           // Canonical empty value
   }

src/share/vm/opto/type.hpp

@@ -367,6 +367,11 @@ public:
     return _const_basic_type[type];
   }
 
+  // For two instance arrays of same dimension, return the base element types.
+  // Otherwise or if the arrays have different dimensions, return NULL.
+  static void get_arrays_base_elements(const Type *a1, const Type *a2,
+                                       const TypeInstPtr **e1, const TypeInstPtr **e2);
+
   // Mapping to the array element's basic type.
   BasicType array_element_basic_type() const;
 

test/compiler/types/TestMeetIncompatibleInterfaceArrays.java

+/*
+ * Copyright 2015 SAP AG.  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.
+ */
+
+/*
+ * @test
+ * @bug 8141551
+ * @summary C2 can not handle returns with inccompatible interface arrays
+ * @library /testlibrary /testlibrary/whitebox/
+ * @build sun.hotspot.WhiteBox
+ * @run main ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm
+ *        -Xbootclasspath/a:.
+ *        -XX:+UnlockDiagnosticVMOptions
+ *        -XX:+WhiteBoxAPI
+ *        -Xbatch
+ *        -XX:CompileThreshold=1
+ *        -XX:-TieredCompilation
+ *        -XX:CICompilerCount=1
+ *        -XX:+PrintCompilation
+ *        -XX:+PrintInlining
+ *        -XX:CompileCommand=compileonly,MeetIncompatibleInterfaceArrays*.run
+ *        -XX:CompileCommand=dontinline,TestMeetIncompatibleInterfaceArrays$Helper.createI2*
+ *        -XX:CompileCommand=quiet
+ *        TestMeetIncompatibleInterfaceArrays 0
+ * @run main/othervm
+ *        -Xbootclasspath/a:.
+ *        -XX:+UnlockDiagnosticVMOptions
+ *        -XX:+WhiteBoxAPI
+ *        -Xbatch
+ *        -XX:CompileThreshold=1
+ *        -XX:-TieredCompilation
+ *        -XX:CICompilerCount=1
+ *        -XX:+PrintCompilation
+ *        -XX:+PrintInlining
+ *        -XX:CompileCommand=compileonly,MeetIncompatibleInterfaceArrays*.run
+ *        -XX:CompileCommand=inline,TestMeetIncompatibleInterfaceArrays$Helper.createI2*
+ *        -XX:CompileCommand=quiet
+ *        TestMeetIncompatibleInterfaceArrays 1
+ * @run main/othervm
+ *        -Xbootclasspath/a:.
+ *        -XX:+UnlockDiagnosticVMOptions
+ *        -XX:+WhiteBoxAPI
+ *        -Xbatch
+ *        -XX:CompileThreshold=1
+ *        -XX:Tier0InvokeNotifyFreqLog=0 -XX:Tier2InvokeNotifyFreqLog=0 -XX:Tier3InvokeNotifyFreqLog=0 -XX:Tier23InlineeNotifyFreqLog=0
+ *        -XX:Tier3InvocationThreshold=2 -XX:Tier3MinInvocationThreshold=2 -XX:Tier3CompileThreshold=2
+ *        -XX:Tier4InvocationThreshold=1 -XX:Tier4MinInvocationThreshold=1 -XX:Tier4CompileThreshold=1
+ *        -XX:+TieredCompilation
+ *        -XX:CICompilerCount=2
+ *        -XX:+PrintCompilation
+ *        -XX:+PrintInlining
+ *        -XX:CompileCommand=compileonly,MeetIncompatibleInterfaceArrays*.run
+ *        -XX:CompileCommand=compileonly,TestMeetIncompatibleInterfaceArrays$Helper.createI2*
+ *        -XX:CompileCommand=inline,TestMeetIncompatibleInterfaceArrays$Helper.createI2*
+ *        -XX:CompileCommand=quiet
+ *        TestMeetIncompatibleInterfaceArrays 2
+ *
+ * @author volker.simonis@gmail.com
+ */
+
+import java.io.FileOutputStream;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import jdk.internal.org.objectweb.asm.ClassWriter;
+import jdk.internal.org.objectweb.asm.MethodVisitor;
+import static jdk.internal.org.objectweb.asm.Opcodes.*;
+import sun.hotspot.WhiteBox;
+
+public class TestMeetIncompatibleInterfaceArrays extends ClassLoader {
+
+    private static final WhiteBox WB = WhiteBox.getWhiteBox();
+
+    public static interface I1 { public String getName(); }
+    public static interface I2 { public String getName(); }
+    public static class I2C implements I2 { public String getName() { return "I2";} }
+    public static class I21C implements I2, I1 { public String getName() { return "I2 and I1";} }
+
+    public static class Helper {
+        public static I2 createI2Array0() {
+            return new I2C();
+        }
+        public static I2[] createI2Array1() {
+            return new I2C[] { new I2C() };
+        }
+        public static I2[][] createI2Array2() {
+            return new I2C[][] { new I2C[] { new I2C() } };
+        }
+        public static I2[][][] createI2Array3() {
+            return new I2C[][][] { new I2C[][] { new I2C[] { new I2C() } } };
+        }
+        public static I2[][][][] createI2Array4() {
+            return new I2C[][][][] { new I2C[][][] { new I2C[][] { new I2C[] { new I2C() } } } };
+        }
+        public static I2[][][][][] createI2Array5() {
+            return new I2C[][][][][] { new I2C[][][][] { new I2C[][][] { new I2C[][] { new I2C[] { new I2C() } } } } };
+        }
+        public static I2 createI21Array0() {
+            return new I21C();
+        }
+        public static I2[] createI21Array1() {
+            return new I21C[] { new I21C() };
+        }
+        public static I2[][] createI21Array2() {
+            return new I21C[][] { new I21C[] { new I21C() } };
+        }
+        public static I2[][][] createI21Array3() {
+            return new I21C[][][] { new I21C[][] { new I21C[] { new I21C() } } };
+        }
+        public static I2[][][][] createI21Array4() {
+            return new I21C[][][][] { new I21C[][][] { new I21C[][] { new I21C[] { new I21C() } } } };
+        }
+        public static I2[][][][][] createI21Array5() {
+            return new I21C[][][][][] { new I21C[][][][] { new I21C[][][] { new I21C[][] { new I21C[] { new I21C() } } } } };
+        }
+    }
+
+    // Location for the generated class files
+    public static final String PATH = System.getProperty("test.classes", ".") + java.io.File.separator;
+
+    /*
+     * With 'good == false' this helper method creates the following classes
+     * (using the nested 'Helper' class and the nested interfaces 'I1' and 'I2').
+     * For brevity I omit the enclosing class 'TestMeetIncompatibleInterfaceArrays' in the
+     * following examples:
+     *
+     * public class MeetIncompatibleInterfaceArrays0ASM {
+     *   public static I1 run() {
+     *     return Helper.createI2Array0(); // returns I2
+     *   }
+     *   public static void test() {
+     *     I1 i1 = run();
+     *     System.out.println(i1.getName());
+     *   }
+     * }
+     * public class MeetIncompatibleInterfaceArrays1ASM {
+     *   public static I1[] run() {
+     *     return Helper.createI2Array1(); // returns I2[]
+     *   }
+     *   public static void test() {
+     *     I1[] i1 = run();
+     *     System.out.println(i1[0].getName());
+     *   }
+     * }
+     * ...
+     * // MeetIncompatibleInterfaceArrays4ASM is special because it creates
+     * // an illegal class which will be rejected by the verifier.
+     * public class MeetIncompatibleInterfaceArrays4ASM {
+     *   public static I1[][][][] run() {
+     *     return Helper.createI2Array3(); // returns I1[][][] which gives a verifier error because return expects I1[][][][]
+     *   }
+     *   public static void test() {
+     *     I1[][][][][] i1 = run();
+     *     System.out.println(i1[0][0][0][0][0].getName());
+     *   }
+     * ...
+     * public class MeetIncompatibleInterfaceArrays5ASM {
+     *   public static I1[][][][][] run() {
+     *     return Helper.createI2Array5(); // returns I2[][][][][]
+     *   }
+     *   public static void test() {
+     *     I1[][][][][] i1 = run();
+     *     System.out.println(i1[0][0][0][0][0].getName());
+     *   }
+     * }
+     *
+     * Notice that this is not legal Java code. We would have to use a cast in "run()" to make it legal:
+     *
+     *   public static I1[] run() {
+     *     return (I1[])Helper.createI2Array1(); // returns I2[]
+     *   }
+     *
+     * But in pure bytecode, the "run()" methods are perfectly legal:
+     *
+     *   public static I1[] run();
+     *     Code:
+     *       0: invokestatic  #16  // Method Helper.createI2Array1:()[LI2;
+     *       3: areturn
+     *
+     * The "test()" method calls the "getName()" function from I1 on the objects returned by "run()".
+     * This will epectedly fail with an "IncompatibleClassChangeError" because the objects returned
+     * by "run()" (and by createI2Array()) are actually of type "I2C" and only implement "I2" but not "I1".
+     *
+     *
+     * With 'good == true' this helper method will create the following classes:
+     *
+     * public class MeetIncompatibleInterfaceArraysGood0ASM {
+     *   public static I1 run() {
+     *     return Helper.createI21Array0(); // returns I2
+     *   }
+     *   public static void test() {
+     *     I1 i1 = run();
+     *     System.out.println(i1.getName());
+     *   }
+     * }
+     *
+     * Calling "test()" on these objects will succeed and output "I2 and I1" because now the "run()"
+     * method calls "createI21Array()" which actually return an object (or an array of objects) of
+     * type "I21C" which implements both "I2" and "I1".
+     *
+     * Notice that at the bytecode level, the code for the "run()" and "test()" methods in
+     * "MeetIncompatibleInterfaceArraysASM" and "MeetIncompatibleInterfaceArraysGoodASM" look exactly
+     * the same. I.e. the verifier has no chance to verify if the I2 object returned by "createI1Array()"
+     * or "createI21Array()" implements "I1" or not. That's actually the reason why both versions of
+     * generated classes are legal from a verifier point of view.
+     *
+     */
+    static void generateTestClass(int dim, boolean good) throws Exception {
+        String baseClassName = "MeetIncompatibleInterfaceArrays";
+        if (good)
+            baseClassName += "Good";
+        String createName = "createI2" + (good ? "1" : "") + "Array";
+        String a = "";
+        for (int i = 0; i < dim; i++)
+            a += "[";
+        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
+        cw.visit(V1_8, ACC_PUBLIC, baseClassName + dim + "ASM", null, "java/lang/Object", null);
+        MethodVisitor constr = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
+        constr.visitCode();
+        constr.visitVarInsn(ALOAD, 0);
+        constr.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
+        constr.visitInsn(RETURN);
+        constr.visitMaxs(0, 0);
+        constr.visitEnd();
+        MethodVisitor run = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "run",
+                "()" + a + "LTestMeetIncompatibleInterfaceArrays$I1;", null, null);
+        run.visitCode();
+        if (dim == 4) {
+            run.visitMethodInsn(INVOKESTATIC, "TestMeetIncompatibleInterfaceArrays$Helper", createName + 3,
+                    "()" + "[[[" + "LTestMeetIncompatibleInterfaceArrays$I2;", false);
+        } else {
+            run.visitMethodInsn(INVOKESTATIC, "TestMeetIncompatibleInterfaceArrays$Helper", createName + dim,
+                    "()" + a + "LTestMeetIncompatibleInterfaceArrays$I2;", false);
+        }
+        run.visitInsn(ARETURN);
+        run.visitMaxs(0, 0);
+        run.visitEnd();
+        MethodVisitor test = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "test", "()V", null, null);
+        test.visitCode();
+        test.visitMethodInsn(INVOKESTATIC, baseClassName + dim + "ASM", "run",
+                "()" + a + "LTestMeetIncompatibleInterfaceArrays$I1;", false);
+        test.visitVarInsn(ASTORE, 0);
+        if (dim > 0) {
+            test.visitVarInsn(ALOAD, 0);
+            for (int i = 1; i <= dim; i++) {
+                test.visitInsn(ICONST_0);
+                test.visitInsn(AALOAD);
+            }
+            test.visitVarInsn(ASTORE, 1);
+        }
+        test.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
+        test.visitVarInsn(ALOAD, dim > 0 ? 1 : 0);
+        test.visitMethodInsn(INVOKEINTERFACE, "TestMeetIncompatibleInterfaceArrays$I1", "getName",
+                "()Ljava/lang/String;", true);
+        test.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/Object;)V", false);
+        test.visitInsn(RETURN);
+        test.visitMaxs(0, 0);
+        test.visitEnd();
+
+        // Get the bytes of the class..
+        byte[] b = cw.toByteArray();
+        // ..and write them into a class file (for debugging)
+        FileOutputStream fos = new FileOutputStream(PATH + baseClassName + dim + "ASM.class");
+        fos.write(b);
+        fos.close();
+
+    }
+
+    public static String[][] tier = { { "interpreted", "C2 (tier 4) without inlining", "C2 (tier4) without inlining" },
+            { "interpreted", "C2 (tier 4) with inlining", "C2 (tier4) with inlining" },
+            { "interpreted", "C1 (tier 3) with inlining", "C2 (tier4) with inlining" } };
+
+    public static void main(String[] args) throws Exception {
+        final int pass = Integer.parseInt(args.length > 0 ? args[0] : "0");
+
+        // Load and initialize some classes required for compilation
+        Class.forName("TestMeetIncompatibleInterfaceArrays$I1");
+        Class.forName("TestMeetIncompatibleInterfaceArrays$I2");
+        Class.forName("TestMeetIncompatibleInterfaceArrays$Helper");
+
+        for (int g = 0; g < 2; g++) {
+            String baseClassName = "MeetIncompatibleInterfaceArrays";
+            boolean good = (g == 0) ? false : true;
+            if (good)
+                baseClassName += "Good";
+            for (int i = 0; i < 6; i++) {
+                System.out.println();
+                System.out.println("Creating " + baseClassName + i + "ASM.class");
+                System.out.println("========================================" + "=" + "=========");
+                // Create the "MeetIncompatibleInterfaceArrays<i>ASM" class
+                generateTestClass(i, good);
+                Class<?> c = null;
+                try {
+                    c = Class.forName(baseClassName + i + "ASM");
+                } catch (VerifyError ve) {
+                    if (i == 4) {
+                        System.out.println("OK - must be (" + ve.getMessage() + ").");
+                    } else {
+                        throw ve;
+                    }
+                    continue;
+                }
+                // Call MeetIncompatibleInterfaceArrays<i>ASM.test()
+                Method m = c.getMethod("test");
+                Method r = c.getMethod("run");
+                for (int j = 0; j < 3; j++) {
+                    System.out.println((j + 1) + ". invokation of " + baseClassName + i + "ASM.test() [should be "
+                            + tier[pass][j] + "]");
+                    try {
+                        m.invoke(null);
+                    } catch (InvocationTargetException ite) {
+                        if (good) {
+                            throw ite;
+                        } else {
+                            if (ite.getCause() instanceof IncompatibleClassChangeError) {
+                                System.out.println("  OK - catched InvocationTargetException("
+                                        + ite.getCause().getMessage() + ").");
+                            } else {
+                                throw ite;
+                            }
+                        }
+                    }
+                }
+                System.out.println("Method " + r + (WB.isMethodCompiled(r) ? " has" : " has not") + " been compiled.");
+                if (!WB.isMethodCompiled(r)) {
+                    throw new Exception("Method " + r + " must be compiled!");
+                }
+            }
+        }
+    }
+}