Find all definitions of the varaible

        :param SimVariable variable: The variable to lookup for.
        :param int size_threshold: The maximum bytes to consider for the variable. For example, if the variable is 100
                                   byte long, only the first `size_threshold` bytes are considered.
        :return: A set of code locations where the variable is defined.
        :rtype: set

def lookup_defs(self, variable, size_threshold=32):
        """
        Find all definitions of the varaible

        :param SimVariable variable: The variable to lookup for.
        :param int size_threshold: The maximum bytes to consider for the variable. For example, if the variable is 100
                                   byte long, only the first `size_threshold` bytes are considered.
        :return: A set of code locations where the variable is defined.
        :rtype: set
        """

        live_def_locs = set()

        if isinstance(variable, SimRegisterVariable):

            if variable.reg is None:
                l.warning('lookup_defs: Got a None for a SimRegisterVariable. Consider fixing.')
                return live_def_locs

            size = min(variable.size, size_threshold)
            offset = variable.reg
            while offset < variable.reg + size:
                if offset in self._register_map:
                    live_def_locs |= self._register_map[offset]
                offset += 1

        elif isinstance(variable, SimMemoryVariable):
            size = min(variable.size, size_threshold)
            offset = variable.addr
            while offset < variable.addr + size:
                if offset in self._memory_map:
                    live_def_locs |= self._memory_map[offset]
                offset += 1

        else:
            # umm unsupported variable type
            l.error('Unsupported variable type "%s".', type(variable))

        return live_def_locs