case INSTR_MUL_FV: pair = INSTR_MUL_VF; goto case_pair_gen;
case INSTR_LT: pair = INSTR_GT; goto case_pair_gen;
case INSTR_GT: pair = INSTR_LT; goto case_pair_gen;
case INSTR_MUL_FV: pair = INSTR_MUL_VF; goto case_pair_gen;
case INSTR_LT: pair = INSTR_GT; goto case_pair_gen;
case INSTR_GT: pair = INSTR_LT; goto case_pair_gen;