addressing two problems in the composite location generation: 1) when a parameter...

addressing two problems in the composite location generation: 1) when a parameter has a composite location which starts with the 'this' reference, we need to add a ordering constraints s.t. the corresponding argument is higher than the parameter composite location in the global value flow, which might cause structure changes of the global flow graph 2) when a callee assigns a new composite location to the return value, we need to changes ordering relations of the global flow graph.