/**
   * Writes the given word to the given writer, after having adapted it, based on the renamed class
   * names.
   */
  private void writeUpdatedWord(Writer writer, String word) throws IOException {
    if (word.length() > 0) {
      String newWord = word;

      boolean containsDots = word.indexOf('.') >= 0;

      // Replace dots by forward slashes.
      String className =
          containsDots ? word.replace('.', ClassConstants.INTERNAL_PACKAGE_SEPARATOR) : word;

      // Find the class corrsponding to the word.
      Clazz clazz = classPool.getClass(className);
      if (clazz != null) {
        // Update the word if necessary.
        String newClassName = clazz.getName();
        if (!className.equals(newClassName)) {
          // Replace forward slashes by dots.
          newWord =
              containsDots
                  ? newClassName.replace(ClassConstants.INTERNAL_PACKAGE_SEPARATOR, '.')
                  : newClassName;
        }
      }

      writer.write(newWord);
    }
  }
  public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    //        DEBUG =
    //            clazz.getName().equals("abc/Def") &&
    //            method.getName(clazz).equals("abc");

    // TODO: Remove this when the code has stabilized.
    // Catch any unexpected exceptions from the actual visiting method.
    try {
      // Process the code.
      visitCodeAttribute0(clazz, method, codeAttribute);
    } catch (RuntimeException ex) {
      System.err.println("Unexpected error while computing stack sizes:");
      System.err.println("  Class       = [" + clazz.getName() + "]");
      System.err.println(
          "  Method      = [" + method.getName(clazz) + method.getDescriptor(clazz) + "]");
      System.err.println(
          "  Exception   = [" + ex.getClass().getName() + "] (" + ex.getMessage() + ")");

      if (DEBUG) {
        method.accept(clazz, new ClassPrinter());
      }

      throw ex;
    }
  }
  public void visitCodeAttribute0(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    if (DEBUG) {
      System.out.println(
          "StackSizeComputer: "
              + clazz.getName()
              + "."
              + method.getName(clazz)
              + method.getDescriptor(clazz));
    }

    // Try to reuse the previous array.
    int codeLength = codeAttribute.u4codeLength;
    if (evaluated.length < codeLength) {
      evaluated = new boolean[codeLength];
      stackSizes = new int[codeLength];
    } else {
      Arrays.fill(evaluated, 0, codeLength, false);
    }

    // The initial stack is always empty.
    stackSize = 0;
    maxStackSize = 0;

    // Evaluate the instruction block starting at the entry point of the method.
    evaluateInstructionBlock(clazz, method, codeAttribute, 0);

    // Evaluate the exception handlers.
    codeAttribute.exceptionsAccept(clazz, method, this);
  }
Beispiel #4
0
  public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    //        DEBUG =
    //            clazz.getName().equals("abc/Def") &&
    //            method.getName(clazz).equals("abc");

    // The minimum variable size is determined by the arguments.
    codeAttribute.u2maxLocals =
        ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz), method.getAccessFlags());

    if (DEBUG) {
      System.out.println(
          "VariableSizeUpdater: "
              + clazz.getName()
              + "."
              + method.getName(clazz)
              + method.getDescriptor(clazz));
      System.out.println("  Max locals: " + codeAttribute.u2maxLocals + " <- parameters");
    }

    // Go over all instructions.
    codeAttribute.instructionsAccept(clazz, method, this);

    // Remove the unused variables of the attributes.
    codeAttribute.attributesAccept(clazz, method, variableCleaner);
  }
 public String toString() {
   return "certain="
       + certain
       + ", depth="
       + depth
       + ": "
       + reason
       + (clazz != null ? clazz.getName() : "(none)")
       + ": "
       + (member != null ? member.getName(clazz) : "(none)");
 }
Beispiel #6
0
  public void visitInnerClassesInfo(Clazz clazz, InnerClassesInfo innerClassesInfo) {
    // At this point, we only mark outer classes of this class.
    // Inner class can be marked later, by InnerUsageMarker.
    if (innerClassesInfo.u2innerClassIndex != 0
        && clazz.getName().equals(clazz.getClassName(innerClassesInfo.u2innerClassIndex))) {
      markAsUsed(innerClassesInfo);

      innerClassesInfo.innerClassConstantAccept(clazz, this);
      innerClassesInfo.outerClassConstantAccept(clazz, this);
      innerClassesInfo.innerNameConstantAccept(clazz, this);
    }
  }
Beispiel #7
0
  public void read(DataEntry dataEntry) throws IOException {
    try {
      // Get the input stream.
      InputStream inputStream = dataEntry.getInputStream();

      // Wrap it into a data input stream.
      DataInputStream dataInputStream = new DataInputStream(inputStream);

      // Create a Clazz representation.
      Clazz clazz;
      if (isLibrary) {
        clazz = new LibraryClass();
        clazz.accept(
            new LibraryClassReader(
                dataInputStream, skipNonPublicLibraryClasses, skipNonPublicLibraryClassMembers));
      } else {
        clazz = new ProgramClass();
        clazz.accept(new ProgramClassReader(dataInputStream));
      }

      // Apply the visitor, if we have a real class.
      String className = clazz.getName();
      if (className != null) {
        if (!dataEntry
                .getName()
                .replace(File.pathSeparatorChar, ClassConstants.PACKAGE_SEPARATOR)
                .equals(className + ClassConstants.CLASS_FILE_EXTENSION)
            && warningPrinter != null) {
          warningPrinter.print(
              className,
              "Warning: class ["
                  + dataEntry.getName()
                  + "] unexpectedly contains class ["
                  + ClassUtil.externalClassName(className)
                  + "]");
        }

        clazz.accept(classVisitor);
      }

      dataEntry.closeInputStream();
    } catch (Exception ex) {
      throw (IOException)
          new IOException(
                  "Can't process class [" + dataEntry.getName() + "] (" + ex.getMessage() + ")")
              .initCause(ex);
    }
  }
  /**
   * Evaluates a block of instructions that hasn't been handled before, starting at the given offset
   * and ending at a branch instruction, a return instruction, or a throw instruction. Branch
   * instructions are handled recursively.
   */
  private void evaluateInstructionBlock(
      Clazz clazz, Method method, CodeAttribute codeAttribute, int instructionOffset) {
    if (DEBUG) {
      if (evaluated[instructionOffset]) {
        System.out.println("-- (instruction block at " + instructionOffset + " already evaluated)");
      } else {
        System.out.println("-- instruction block:");
      }
    }

    // Remember the initial stack size.
    int initialStackSize = stackSize;

    // Remember the maximum stack size.
    if (maxStackSize < stackSize) {
      maxStackSize = stackSize;
    }

    // Evaluate any instructions that haven't been evaluated before.
    while (!evaluated[instructionOffset]) {
      // Mark the instruction as evaluated.
      evaluated[instructionOffset] = true;

      Instruction instruction = InstructionFactory.create(codeAttribute.code, instructionOffset);

      if (DEBUG) {
        int stackPushCount = instruction.stackPushCount(clazz);
        int stackPopCount = instruction.stackPopCount(clazz);
        System.out.println(
            "["
                + instructionOffset
                + "]: "
                + stackSize
                + " - "
                + stackPopCount
                + " + "
                + stackPushCount
                + " = "
                + (stackSize + stackPushCount - stackPopCount)
                + ": "
                + instruction.toString(instructionOffset));
      }

      // Compute the instruction's effect on the stack size.
      stackSize -= instruction.stackPopCount(clazz);

      if (stackSize < 0) {
        throw new IllegalArgumentException(
            "Stack size becomes negative after instruction "
                + instruction.toString(instructionOffset)
                + " in ["
                + clazz.getName()
                + "."
                + method.getName(clazz)
                + method.getDescriptor(clazz)
                + "]");
      }

      stackSizes[instructionOffset] = stackSize += instruction.stackPushCount(clazz);

      // Remember the maximum stack size.
      if (maxStackSize < stackSize) {
        maxStackSize = stackSize;
      }

      // Remember the next instruction offset.
      int nextInstructionOffset = instructionOffset + instruction.length(instructionOffset);

      // Visit the instruction, in order to handle branches.
      instruction.accept(clazz, method, codeAttribute, instructionOffset, this);

      // Stop evaluating after a branch.
      if (exitInstructionBlock) {
        break;
      }

      // Continue with the next instruction.
      instructionOffset = nextInstructionOffset;

      if (DEBUG) {
        if (evaluated[instructionOffset]) {
          System.out.println("-- (instruction at " + instructionOffset + " already evaluated)");
        }
      }
    }

    // Restore the stack size for possible subsequent instruction blocks.
    this.stackSize = initialStackSize;
  }
  public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    //        DEBUG =
    //            clazz.getName().equals("abc/Def") &&
    //            method.getName(clazz).equals("abc");

    if (DEBUG) {
      method.accept(clazz, new ClassPrinter());
    }

    branchTargetFinder.visitCodeAttribute(clazz, method, codeAttribute);

    // Don't bother if there aren't any subroutines anyway.
    if (!containsSubroutines(codeAttribute)) {
      return;
    }

    if (DEBUG) {
      System.out.println(
          "SubroutineInliner: processing ["
              + clazz.getName()
              + "."
              + method.getName(clazz)
              + method.getDescriptor(clazz)
              + "]");
    }

    // Append the body of the code.
    codeAttributeComposer.reset();
    codeAttributeComposer.beginCodeFragment(codeAttribute.u4codeLength);

    // Copy the non-subroutine instructions.
    int offset = 0;
    while (offset < codeAttribute.u4codeLength) {
      Instruction instruction = InstructionFactory.create(codeAttribute.code, offset);
      int instructionLength = instruction.length(offset);

      // Is this returning subroutine?
      if (branchTargetFinder.isSubroutine(offset)
          && branchTargetFinder.isSubroutineReturning(offset)) {
        // Skip the subroutine.
        if (DEBUG) {
          System.out.println(
              "  Skipping original subroutine instruction " + instruction.toString(offset));
        }

        // Append a label at this offset instead.
        codeAttributeComposer.appendLabel(offset);
      } else {
        // Copy the instruction, inlining any subroutine call recursively.
        instruction.accept(clazz, method, codeAttribute, offset, this);
      }

      offset += instructionLength;
    }

    // Copy the exceptions. Note that exceptions with empty try blocks
    // are automatically removed.
    codeAttribute.exceptionsAccept(clazz, method, subroutineExceptionInliner);

    if (DEBUG) {
      System.out.println("  Appending label after code at [" + offset + "]");
    }

    // Append a label just after the code.
    codeAttributeComposer.appendLabel(codeAttribute.u4codeLength);

    // End and update the code attribute.
    codeAttributeComposer.endCodeFragment();
    codeAttributeComposer.visitCodeAttribute(clazz, method, codeAttribute);

    if (DEBUG) {
      method.accept(clazz, new ClassPrinter());
    }
  }
  /**
   * Returns the most specific common superclass or interface of the given classes.
   *
   * @param class1 the first class.
   * @param class2 the second class.
   * @param interfaces specifies whether to look for a superclass or for an interface.
   * @return the common class.
   */
  private Clazz findCommonClass(Clazz class1, Clazz class2, boolean interfaces) {
    // Collect the superclasses or the interfaces of this class.
    Set superClasses1 = new HashSet();
    class1.hierarchyAccept(
        !interfaces, !interfaces, interfaces, false, new ClassCollector(superClasses1));

    int superClasses1Count = superClasses1.size();
    if (superClasses1Count == 0) {
      if (interfaces) {
        return null;
      } else if (class1.getSuperName() != null) {
        throw new IllegalArgumentException(
            "Can't find any super classes of ["
                + class1.getName()
                + "] (not even immediate super class ["
                + class1.getSuperName()
                + "])");
      }
    }

    // Collect the superclasses or the interfaces of the other class.
    Set superClasses2 = new HashSet();
    class2.hierarchyAccept(
        !interfaces, !interfaces, interfaces, false, new ClassCollector(superClasses2));

    int superClasses2Count = superClasses2.size();
    if (superClasses2Count == 0) {
      if (interfaces) {
        return null;
      } else if (class2.getSuperName() != null) {
        throw new IllegalArgumentException(
            "Can't find any super classes of ["
                + class2.getName()
                + "] (not even immediate super class ["
                + class2.getSuperName()
                + "])");
      }
    }

    if (DEBUG) {
      System.out.println(
          "ReferenceValue.generalize this ["
              + class1.getName()
              + "] with other ["
              + class2.getName()
              + "] (interfaces = "
              + interfaces
              + ")");
      System.out.println("  This super classes:  " + superClasses1);
      System.out.println("  Other super classes: " + superClasses2);
    }

    // Find the common superclasses.
    superClasses1.retainAll(superClasses2);

    if (DEBUG) {
      System.out.println("  Common super classes: " + superClasses1);
    }

    if (interfaces && superClasses1.isEmpty()) {
      return null;
    }

    // Find a class that is a subclass of all common superclasses,
    // or that at least has the maximum number of common superclasses.
    Clazz commonClass = null;

    int maximumSuperClassCount = -1;

    // Go over all common superclasses to find it. In case of
    // multiple subclasses, keep the lowest one alphabetically,
    // in order to ensure that the choice is deterministic.
    Iterator commonSuperClasses = superClasses1.iterator();
    while (commonSuperClasses.hasNext()) {
      Clazz commonSuperClass = (Clazz) commonSuperClasses.next();

      int superClassCount = superClassCount(commonSuperClass, superClasses1);
      if (maximumSuperClassCount < superClassCount
          || (maximumSuperClassCount == superClassCount
              && commonClass != null
              && commonClass.getName().compareTo(commonSuperClass.getName()) > 0)) {
        commonClass = commonSuperClass;
        maximumSuperClassCount = superClassCount;
      }
    }

    if (commonClass == null) {
      throw new IllegalArgumentException(
          "Can't find common super class of ["
              + class1.getName()
              + "] (with "
              + superClasses1Count
              + " known super classes) and ["
              + class2.getName()
              + "] (with "
              + superClasses2Count
              + " known super classes)");
    }

    if (DEBUG) {
      System.out.println("  Best common class: [" + commonClass.getName() + "]");
    }

    return commonClass;
  }
  public ReferenceValue generalize(TypedReferenceValue other) {
    // If both types are identical, the generalization is the same too.
    if (this.equals(other)) {
      return this;
    }

    String thisType = this.type;
    String otherType = other.type;

    // If both types are nul, the generalization is null too.
    if (thisType == null && otherType == null) {
      return ValueFactory.REFERENCE_VALUE_NULL;
    }

    // If this type is null, the generalization is the other type, maybe null.
    if (thisType == null) {
      return other.generalizeMayBeNull(true);
    }

    // If the other type is null, the generalization is this type, maybe null.
    if (otherType == null) {
      return this.generalizeMayBeNull(true);
    }

    boolean mayBeNull = this.mayBeNull || other.mayBeNull;

    // If the two types are equal, the generalization remains the same, maybe null.
    if (thisType.equals(otherType)) {
      return typedReferenceValue(this, mayBeNull);
    }

    // Start taking into account the type dimensions.
    int thisDimensionCount = ClassUtil.internalArrayTypeDimensionCount(thisType);
    int otherDimensionCount = ClassUtil.internalArrayTypeDimensionCount(otherType);
    int commonDimensionCount = Math.min(thisDimensionCount, otherDimensionCount);

    if (thisDimensionCount == otherDimensionCount) {
      // See if we can take into account the referenced classes.
      Clazz thisReferencedClass = this.referencedClass;
      Clazz otherReferencedClass = other.referencedClass;

      if (thisReferencedClass != null && otherReferencedClass != null) {
        // Is one class simply an extension of the other one?
        if (thisReferencedClass.extendsOrImplements(otherReferencedClass)) {
          return typedReferenceValue(other, mayBeNull);
        }

        if (otherReferencedClass.extendsOrImplements(thisReferencedClass)) {
          return typedReferenceValue(this, mayBeNull);
        }

        // Do the classes have a non-trivial common superclass?
        Clazz commonClass = findCommonClass(thisReferencedClass, otherReferencedClass, false);

        if (commonClass.getName().equals(ClassConstants.NAME_JAVA_LANG_OBJECT)) {
          // Otherwise, do the classes have a common interface?
          Clazz commonInterface = findCommonClass(thisReferencedClass, otherReferencedClass, true);
          if (commonInterface != null) {
            commonClass = commonInterface;
          }
        }

        return new TypedReferenceValue(
            commonDimensionCount == 0
                ? commonClass.getName()
                : ClassUtil.internalArrayTypeFromClassName(
                    commonClass.getName(), commonDimensionCount),
            commonClass,
            mayBeNull);
      }
    } else if (thisDimensionCount > otherDimensionCount) {
      // See if the other type is an interface type of arrays.
      if (ClassUtil.isInternalArrayInterfaceName(
          ClassUtil.internalClassNameFromClassType(otherType))) {
        return typedReferenceValue(other, mayBeNull);
      }
    } else if (thisDimensionCount < otherDimensionCount) {
      // See if this type is an interface type of arrays.
      if (ClassUtil.isInternalArrayInterfaceName(
          ClassUtil.internalClassNameFromClassType(thisType))) {
        return typedReferenceValue(this, mayBeNull);
      }
    }

    // Reduce the common dimension count if either type is an array of
    // primitives type of this dimension.
    if (commonDimensionCount > 0
            && (ClassUtil.isInternalPrimitiveType(otherType.charAt(commonDimensionCount)))
        || ClassUtil.isInternalPrimitiveType(thisType.charAt(commonDimensionCount))) {
      commonDimensionCount--;
    }

    // Fall back on a basic Object or array of Objects type.
    return commonDimensionCount != 0
        ? new TypedReferenceValue(
            ClassUtil.internalArrayTypeFromClassName(
                ClassConstants.NAME_JAVA_LANG_OBJECT, commonDimensionCount),
            null,
            mayBeNull)
        : mayBeNull
            ? ValueFactory.REFERENCE_VALUE_JAVA_LANG_OBJECT_MAYBE_NULL
            : ValueFactory.REFERENCE_VALUE_JAVA_LANG_OBJECT_NOT_NULL;
  }
Beispiel #12
0
  public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    // Get the original parameter size that was saved.
    int oldParameterSize = ParameterUsageMarker.getParameterSize(method);

    // Compute the new parameter size from the shrunk descriptor.
    int newParameterSize =
        ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz), method.getAccessFlags());

    if (oldParameterSize > newParameterSize) {
      // Get the total size of the local variable frame.
      int maxLocals = codeAttribute.u2maxLocals;

      if (DEBUG) {
        System.out.println(
            "ParameterShrinker: "
                + clazz.getName()
                + "."
                + method.getName(clazz)
                + method.getDescriptor(clazz));
        System.out.println("  Old parameter size = " + oldParameterSize);
        System.out.println("  New parameter size = " + newParameterSize);
        System.out.println("  Max locals         = " + maxLocals);
      }

      // Create a variable map.
      int[] variableMap = new int[maxLocals];

      // Move unused parameters right after the parameter block.
      int usedParameterIndex = 0;
      int unusedParameterIndex = newParameterSize;
      for (int parameterIndex = 0; parameterIndex < oldParameterSize; parameterIndex++) {
        // Is the variable required as a parameter?
        if (ParameterUsageMarker.isParameterUsed(method, parameterIndex)) {
          // Keep the variable as a parameter.
          variableMap[parameterIndex] = usedParameterIndex++;
        } else {
          if (DEBUG) {
            System.out.println("  Deleting parameter #" + parameterIndex);
          }

          // Shift the variable to the unused parameter block,
          // in case it is still used as a variable.
          variableMap[parameterIndex] = unusedParameterIndex++;

          // Visit the method, if required.
          if (extraVariableMemberVisitor != null) {
            method.accept(clazz, extraVariableMemberVisitor);
          }
        }
      }

      // Fill out the remainder of the map.
      for (int variableIndex = oldParameterSize; variableIndex < maxLocals; variableIndex++) {
        variableMap[variableIndex] = variableIndex;
      }

      // Set the map.
      variableRemapper.setVariableMap(variableMap);

      // Remap the variables.
      variableRemapper.visitCodeAttribute(clazz, method, codeAttribute);
    }
  }
  /** Returns the generalization of this ReferenceValue and the given other ReferenceValue. */
  public ReferenceValue generalize(ReferenceValue other) {
    // If both types are identical, the generalization is the same too.
    if (this.equals(other)) {
      return this;
    }

    String thisType = this.type;
    String otherType = other.type;

    // If both types are nul, the generalization is null too.
    if (thisType == null && otherType == null) {
      return ValueFactory.REFERENCE_VALUE_NULL;
    }

    // If this type is null, the generalization is the other type, maybe null.
    if (thisType == null) {
      return other.generalizeMayBeNull(true);
    }

    // If the other type is null, the generalization is this type, maybe null.
    if (otherType == null) {
      return this.generalizeMayBeNull(true);
    }

    boolean mayBeNull = this.mayBeNull || other.mayBeNull;

    // If the two types are equal, the generalization remains the same, maybe null.
    if (thisType.equals(otherType)) {
      return this.generalizeMayBeNull(mayBeNull);
    }

    // Start taking into account the type dimensions.
    int thisDimensionCount = ClassUtil.internalArrayTypeDimensionCount(thisType);
    int otherDimensionCount = ClassUtil.internalArrayTypeDimensionCount(otherType);
    int commonDimensionCount = Math.min(thisDimensionCount, otherDimensionCount);

    if (thisDimensionCount == otherDimensionCount) {
      // See if we can take into account the referenced classes.
      Clazz thisReferencedClass = this.referencedClass;
      Clazz otherReferencedClass = other.referencedClass;

      if (thisReferencedClass != null && otherReferencedClass != null) {
        if (thisReferencedClass.extendsOrImplements(otherReferencedClass)) {
          return other.generalizeMayBeNull(mayBeNull);
        }

        if (otherReferencedClass.extendsOrImplements(thisReferencedClass)) {
          return this.generalizeMayBeNull(mayBeNull);
        }

        // Collect the superclasses and interfaces of this class.
        Set thisSuperClasses = new HashSet();
        thisReferencedClass.hierarchyAccept(
            false, true, true, false, new ClassCollector(thisSuperClasses));

        int thisSuperClassesCount = thisSuperClasses.size();
        if (thisSuperClassesCount == 0 && thisReferencedClass.getSuperName() != null) {
          throw new IllegalArgumentException(
              "Can't find any super classes of ["
                  + thisType
                  + "] (not even immediate super class ["
                  + thisReferencedClass.getSuperName()
                  + "])");
        }

        // Collect the superclasses and interfaces of the other class.
        Set otherSuperClasses = new HashSet();
        otherReferencedClass.hierarchyAccept(
            false, true, true, false, new ClassCollector(otherSuperClasses));

        int otherSuperClassesCount = otherSuperClasses.size();
        if (otherSuperClassesCount == 0 && otherReferencedClass.getSuperName() != null) {
          throw new IllegalArgumentException(
              "Can't find any super classes of ["
                  + otherType
                  + "] (not even immediate super class ["
                  + otherReferencedClass.getSuperName()
                  + "])");
        }

        if (DEBUG) {
          System.out.println(
              "ReferenceValue.generalize this ["
                  + thisReferencedClass.getName()
                  + "] with other ["
                  + otherReferencedClass.getName()
                  + "]");
          System.out.println("  This super classes:  " + thisSuperClasses);
          System.out.println("  Other super classes: " + otherSuperClasses);
        }

        // Find the common superclasses.
        thisSuperClasses.retainAll(otherSuperClasses);

        if (DEBUG) {
          System.out.println("  Common super classes: " + thisSuperClasses);
        }

        // Find a class that is a subclass of all common superclasses,
        // or that at least has the maximum number of common superclasses.
        Clazz commonClass = null;

        int maximumSuperClassCount = -1;

        // Go over all common superclasses to find it. In case of
        // multiple subclasses, keep the lowest one alphabetically,
        // in order to ensure that the choice is deterministic.
        Iterator commonSuperClasses = thisSuperClasses.iterator();
        while (commonSuperClasses.hasNext()) {
          Clazz commonSuperClass = (Clazz) commonSuperClasses.next();

          int superClassCount = superClassCount(commonSuperClass, thisSuperClasses);
          if (maximumSuperClassCount < superClassCount
              || (maximumSuperClassCount == superClassCount
                  && commonClass != null
                  && commonClass.getName().compareTo(commonSuperClass.getName()) > 0)) {
            commonClass = commonSuperClass;
            maximumSuperClassCount = superClassCount;
          }
        }

        if (commonClass == null) {
          throw new IllegalArgumentException(
              "Can't find common super class of ["
                  + thisType
                  + "] (with "
                  + thisSuperClassesCount
                  + " known super classes) and ["
                  + otherType
                  + "] (with "
                  + otherSuperClassesCount
                  + " known super classes)");
        }

        if (DEBUG) {
          System.out.println("  Best common class: [" + commonClass.getName() + "]");
        }

        // TODO: Handle more difficult cases, with multiple global subclasses.

        return new ReferenceValue(
            commonDimensionCount == 0
                ? commonClass.getName()
                : ClassUtil.internalArrayTypeFromClassName(
                    commonClass.getName(), commonDimensionCount),
            commonClass,
            mayBeNull);
      }
    } else if (thisDimensionCount > otherDimensionCount) {
      // See if the other type is an interface type of arrays.
      if (ClassUtil.isInternalArrayInterfaceName(
          ClassUtil.internalClassNameFromClassType(otherType))) {
        return other.generalizeMayBeNull(mayBeNull);
      }
    } else if (thisDimensionCount < otherDimensionCount) {
      // See if this type is an interface type of arrays.
      if (ClassUtil.isInternalArrayInterfaceName(
          ClassUtil.internalClassNameFromClassType(thisType))) {
        return this.generalizeMayBeNull(mayBeNull);
      }
    }

    // Reduce the common dimension count if either type is an array of
    // primitives type of this dimension.
    if (commonDimensionCount > 0
            && (ClassUtil.isInternalPrimitiveType(otherType.charAt(commonDimensionCount)))
        || ClassUtil.isInternalPrimitiveType(thisType.charAt(commonDimensionCount))) {
      commonDimensionCount--;
    }

    // Fall back on a basic Object or array of Objects type.
    return commonDimensionCount == 0
        ? mayBeNull
            ? ValueFactory.REFERENCE_VALUE_JAVA_LANG_OBJECT_MAYBE_NULL
            : ValueFactory.REFERENCE_VALUE_JAVA_LANG_OBJECT_NOT_NULL
        : new ReferenceValue(
            ClassUtil.internalArrayTypeFromClassName(
                ClassConstants.INTERNAL_NAME_JAVA_LANG_OBJECT, commonDimensionCount),
            null,
            mayBeNull);
  }