REG_MATCH_NULL_STRING_P
REG_MATCH_NULL_STRING_P (reg_info[this_reg])); \
REG_MATCH_NULL_STRING_P (reg_info[mcnt]) = MATCH_NULL_UNSET_VALUE;
if (REG_MATCH_NULL_STRING_P (reg_info[*p]) == MATCH_NULL_UNSET_VALUE)
REG_MATCH_NULL_STRING_P (reg_info[*p])
old_regstart[*p] = REG_MATCH_NULL_STRING_P (reg_info[*p])
old_regend[*p] = REG_MATCH_NULL_STRING_P (reg_info[*p])
if (REG_MATCH_NULL_STRING_P (reg_info[reg_no]) == MATCH_NULL_UNSET_VALUE)
REG_MATCH_NULL_STRING_P (reg_info[reg_no]) = ret;
if (!REG_MATCH_NULL_STRING_P (reg_info[*p1]))