Beispiel #1
0
 /**
  * Emulates the storing of a value to a local variable.
  *
  * @param index the index of the local variable being stored to
  * @param type the type of the value
  * @param local the variable to which the value is stored
  */
 public void store(int index, Klass type, Local local) {
   Klass localType = local.getType();
   Assert.that(localType.isAssignableFrom(type) || localType == getLocalTypeFor(type));
   verifyLocalVariableIndex(localType, index);
   localTypes[index] = type;
   if (localType.isDoubleWord()) {
     localTypes[index + 1] = Klass.getSecondWordType(localType);
   } else {
     verifyUseOfSquawkPrimitive(localType, type);
   }
 }
Beispiel #2
0
 /**
  * Verify that a local variable index for a given type is not out of bounds.
  *
  * @param type the type of the local variable at <code>index</code> in the local variables array
  * @param index the index of a local variable
  */
 public void verifyLocalVariableIndex(Klass type, int index) {
   if (index < 0) {
     throw codeParser.verifyError("invalid local variable index");
   }
   if (type.isDoubleWord()) {
     index++;
   }
   if (index >= localTypes.length) {
     throw codeParser.verifyError("invalid local variable index");
   }
 }
Beispiel #3
0
  /**
   * Pops a value off the operand stack.
   *
   * @param type the type that the value popped off the operand stack must be assignable to
   * @return the instruction that produced the popped value
   */
  public StackProducer pop(Klass type) {
    StackProducer producer;
    if (type.isDoubleWord()) {
      if (sp < 2) {
        throw codeParser.verifyError("operand stack underflow");
      }
      if (!isTopDoubleWord()) {
        throw codeParser.verifyError("incompatible type on operand stack " + tosKlassName());
      }
      sp -= 2;
      producer = stack[sp];
    } else {
      if (sp < 1) {
        throw codeParser.verifyError("operand stack underflow");
      }
      if (isTopDoubleWord()) {
        throw codeParser.verifyError("incompatible type on operand stack " + tosKlassName());
      }
      producer = stack[--sp];

      /*
       * The primitive one-word, non-float types are all assignment compatible with each other
       */
      if (type.isPrimitive() && type != Klass.FLOAT) {

        type = Klass.INT;
      }
    }

    Assert.that(producer != null);

    /*
     * Interfaces are treated as java.lang.Object in the verifier.
     */
    if (type.isInterface()) {
      type = Klass.OBJECT;
    }

    /*
     * Verify that the instruction is producing the correct type.
     */
    if (!type.isAssignableFrom(producer.getType())) {
      throw codeParser.verifyError(
          "incompatible type: '" + type + "' is not assignable from '" + producer.getType() + "'");
    }

    return producer;
  }
Beispiel #4
0
  /**
   * Emulates loading a value of a given type from a local variable.
   *
   * @param index the index of the local variable being loaded from
   * @param localType the expected type of the variable from which the value is loaded
   * @return the variable from which the value is loaded
   */
  public Local load(int index, Klass localType) {
    verifyLocalVariableIndex(localType, index);
    Klass derivedType = localTypes[index];
    if (!localType.isAssignableFrom(derivedType)) {
      throw codeParser.verifyError("incompatible type in local variable");
    }

    if (localType.isDoubleWord()) {
      Klass secondWordType = Klass.getSecondWordType(localType);
      if (!secondWordType.isAssignableFrom(localTypes[index + 1])) {
        throw codeParser.verifyError("incompatible type in local variable");
      }
    }

    if (derivedType.isSquawkPrimitive()) {
      localType = derivedType;
    }
    return allocateLocal(localType, index);
  }
Beispiel #5
0
  /**
   * Pushes a value to the operand stack.
   *
   * @param producer the instruction producing the value being pushed
   */
  public void push(StackProducer producer) {
    Klass type = producer.getType();
    Assert.that(type != Klass.VOID);

    /*
     * Check for overflow and push the producer.
     */
    if (sp == maxStack) {
      throw codeParser.verifyError("operand stack overflow");
    }
    stack[sp++] = producer;

    /*
     * For long and double check for overflow and then add a null word to the stack.
     */
    if (type.isDoubleWord()) {
      if (sp == maxStack) {
        throw codeParser.verifyError("operand stack overflow");
      }
      stack[sp++] = null;
    }
  }
Beispiel #6
0
  /**
   * Creates a Frame instance to emulate and verify the execution of a single class file method.
   *
   * @param codeParser the parser used to parse the "Code" attribute of the method being emulated
   * @param extraLocals the number of extra local variables needed
   */
  public Frame(CodeParser codeParser, int extraLocals) {
    this.maxStack = codeParser.getMaxStack();
    this.codeParser = codeParser;

    /*
     * Initialize the operand stack
     */
    stack = new StackProducer[maxStack];

    /*
     * Initialize the types in the local variables
     */
    localTypes = new Klass[codeParser.getMaxLocals() + extraLocals];
    Method method = codeParser.getMethod();
    Klass[] parameterTypes = method.getParameterTypes();
    Local[] parameterLocals = null;
    if (Translator.REVERSE_PARAMETERS && method.isInterpreterInvoked()) {
      parameterLocals = new Local[parameterTypes.length];
    }
    int javacIndex = 0;

    /*
     * Initialize 'this' in non-static methods. The type of 'this' is
     * UNINITIALIZED_THIS if this method is a constructor in any class
     * except java.lang.Object otherwise it is the class in which the
     * method was defined.
     */
    if (!method.isStatic() || method.isConstructor()) {
      Assert.that(parameterLocals == null);
      Klass thisType = method.getDefiningClass();
      if (method.isConstructor() && thisType != Klass.OBJECT) {
        thisType = Klass.UNINITIALIZED_THIS;
      }
      Local thisLocal = allocateParameter(thisType, javacIndex);
      store(javacIndex, thisType, thisLocal);
      javacIndex++;
    }

    /*
     * Initialize locals for the parameters.
     */
    int parameterIndex = javacIndex;
    for (int i = 0; i < parameterTypes.length; i++) {
      Klass parameterType = parameterTypes[i];
      Local parameterLocal = allocateParameter(parameterType, javacIndex);
      if (parameterLocals != null) {
        parameterLocals[i] = parameterLocal;
      }
      if (Klass.SQUAWK_64) {
        if (javacIndex != parameterIndex) {
          Assert.that(parameterIndex < javacIndex);
          parameterLocal.setParameterIndex(parameterIndex);
        }
        parameterIndex++;
      }
      store(javacIndex, parameterType, parameterLocal);
      javacIndex += (parameterType.isDoubleWord() ? 2 : 1);
    }
    parameterLocalsCount = javacIndex;

    /*
     * Adjust the parameter offsets for parameter order reversal.
     */
    if (parameterLocals != null) {
      parameterIndex = 0;
      for (int i = parameterTypes.length - 1; i >= 0; i--) {
        Klass parameterType = parameterTypes[i];
        parameterLocals[i].setParameterIndex(parameterIndex++);
        if (!Klass.SQUAWK_64 && parameterType.isDoubleWord()) {
          parameterIndex++;
        }
      }
    }

    /*
     * Initialize the remaining local variables to the TOP type
     */
    while (javacIndex < localTypes.length) {
      localTypes[javacIndex++] = Klass.TOP;
    }
  }