Example #1
0
  /**
   * Get a <code>Local</code> instance to represent a value of a given type that will be
   * stored/loaded to/from a given local variable.
   *
   * @param type the type of the value
   * @param index the index of the local variable
   * @param isParameter true if the local is a parameter
   * @return the variable at index <code>index</code> in which values of type <code>type</code> are
   *     stored
   */
  private Local allocateLocalPrim(Klass type, int index, boolean isParameter) {
    Assert.that(localTypes.length < 0xFFFF);
    Assert.that(
        index >= 0 && index < localTypes.length,
        "index=" + index + " localTypes.length=" + localTypes.length);

    Klass localType = getLocalTypeFor(type);

    int key = localType.getSuiteID();

    /* We need a hard partition between uses of a slot as a reference vs. an Address, Offset, or UWord.
     * The partitioning of java primitives and objects is accomplished not only by the type passed in here, but
     * by the bytecode verifier. We can't be sure that some bytecodes are refering to the same local variable
     * as both a reference and as a Squawk primitive. Without that kind of support we are conservative here
     * and force a clash whenever javac uses the same local index for a reference and a Squawk primitive.
     */
    if (localType.isSquawkPrimitive()) {
      key = Klass.REFERENCE.getSuiteID();
    }
    key = key << 16 | index;
    if (localValues == null) {
      localValues = new IntHashtable();
    }
    Local local = (Local) localValues.get(key);
    if (local == null) {
      local = new Local(localType, index, isParameter);
      localValues.put(key, local);
    }

    /*
     * Ensure that the original class file does not use the same local variable
     * for both a Squawk primitive value and any other reference value. This prevents the
     * translator from having to do a complete liveness analysis to de-multiplex
     * such a local variable slot. Such de-multiplexing is required as Squawk primitives
     * are 'magically' translated into integers (or longs on a 64 bit system).
     */
    if (localType.isSquawkPrimitive() || local.getType().isSquawkPrimitive()) {
      if (localType != local.getType()) {
        throw codeParser.verifyError(
            getBadAddressLocalVariableMessage(index, localType, local.getType()));
      }
    }

    // System.out.println("allocated: "+local+" index "+index);
    /// *if[SCOPEDLOCALVARIABLES]*/
    codeParser.localVariableAllocated(codeParser.getCurrentIP(), local);
    /// *end[SCOPEDLOCALVARIABLES]*/
    return local;
  }
Example #2
0
 /**
  * Tests two given types to ensure that they are both {@link Klass#isSquawkPrimitive() Squawk
  * primitives} or both not Squawk primitives. If they are both Squawk primitives, then they must
  * be exactly the same type. This enforces the constraint that Squawk primitive values cannot be
  * assigned to or compared with any other type.
  *
  * @param type1 the first type to compare
  * @param type2 the second type to compare
  */
 public void verifyUseOfSquawkPrimitive(Klass type1, Klass type2) {
   if (type1.isSquawkPrimitive() || type2.isSquawkPrimitive()) {
     if (type1 != type2) {
       // Offsets are implemented as Words
       //                if (type1.getClassID() + type2.getClassID() != CID.UWORD + CID.OFFSET) {
       String type = type1.getName();
       throw codeParser.verifyError(
           type
               + " values can only be written to or compared with other "
               + type
               + " values, not with "
               + type2.getName());
       //                }
     }
   }
 }
Example #3
0
 /**
  * Creates and returns the detailed error message when a local variable is used as a Squawk
  * primitive as well as some value not of exactly the same type. The message includes information
  * derived from the LocalVariableTable attribute so that the source code can be easily changed.
  *
  * @param index the local variable index that is (mis)used
  * @return the detailed error message
  */
 private String getBadAddressLocalVariableMessage(int index, Klass type1, Klass type2) {
   Assert.that(type1.isSquawkPrimitive() || type2.isSquawkPrimitive());
   if (type2.isSquawkPrimitive()) {
     Klass otherType = type1;
     type1 = type2;
     type2 = otherType;
   }
   StringBuffer buf =
       new StringBuffer(
           "Stack location "
               + index
               + " cannot be used for both a local variable of type "
               + type1.getName()
               + " and of type "
               + type2.getName()
               + ". Try moving the variable of type "
               + type1.getName()
               + " to the top-most scope of the method.");
   Enumeration e = codeParser.getLocalVariableTableEntries();
   if (e != null) {
     buf.append(" (source code usage: ");
     while (e.hasMoreElements()) {
       LocalVariableTableEntry entry = (LocalVariableTableEntry) e.nextElement();
       if (entry.getIndex() == index) {
         int start = codeParser.getSourceLineNumber(entry.getStart().getBytecodeOffset());
         int end = codeParser.getSourceLineNumber(entry.getEnd().getBytecodeOffset());
         buf.append(entry.getType().getName())
             .append(' ')
             .append(entry.getName())
             .append(" from line ")
             .append(start)
             .append(" to line ")
             .append(end)
             .append(';');
       }
     }
   }
   return buf.toString();
 }
Example #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);
  }