Simplify all function call statements.

        :return:    None

def _make_callsites(self, stack_pointer_tracker=None):
        """
        Simplify all function call statements.

        :return:    None
        """

        # Computing reaching definitions
        rd = self.project.analyses.ReachingDefinitions(func=self.function, func_graph=self.graph, observe_all=True)

        for key in self._blocks:
            block = self._blocks[key]
            csm = self.project.analyses.AILCallSiteMaker(block, reaching_definitions=rd)
            if csm.result_block:
                ail_block = csm.result_block
                simp = self.project.analyses.AILBlockSimplifier(ail_block, stack_pointer_tracker=stack_pointer_tracker)
                self._blocks[key] = simp.result_block

        self._update_graph()