symbolic array dimensions are inverted

[Stephen Siegel]

If you ask the symbolic package for the array type with element type int[X1] and length X2, it returns the type int[X1][X2], when it should return the type int[X2][X1].

I think this is because there is a bug in the way the type is converted to a string in SymArray:

	public String toString()
	{
		String result =  baseType.toString() + "[";
		
		if (dimension != null) result += dimension.toString();
		result += "]";
		return result;
	}

and then this String is used as a key in a hashtable to retrieve the type in SymUniverse:

	public SymType arrayType(SymType elementType, SymExpression dimension)
	{
		SymType temp = new SymArray(elementType, dimension);
		if(typeTable.containsKey(temp.toString()))
		{
			return typeTable.get(temp.toString());
		}
		else
		{
			typeTable.put(temp.toString(), temp);
			return temp;
		}
	}

By the way, I don't think it is a good idea to use the strings as keys in the hashtables. For one thing, constructing strings is very slow. It is also easy to make a mistake. Better to use something with a simple logic, like just give all the types a hashCode and look them up that way.

[ywei]

Bug fixed. The SymArray class now correctly place the dimension information in an orderly way. And I also changed the SymUniverse so that it doesn't use the string presentation of a symbolic type as the key in the type table.