Compute effective address (getelementptr):
            name = getelementptr ptr, <indices...>

def gep(self, ptr, indices, inbounds=False, name=''):
        """
        Compute effective address (getelementptr):
            name = getelementptr ptr, <indices...>
        """
        instr = instructions.GEPInstr(self.block, ptr, indices,
                                      inbounds=inbounds, name=name)
        self._insert(instr)
        return instr