If I fail PhD, what is the appropriate way to present myself in CV for jobs in industry?

You can put "admitted to candidacy" or "all but dissertation" or something like that in your CV.

In the the interview, you can say that you got a lot out of your studies, but that you've realized that the academic life is not for you. Be prepared to give one reason if necessary, and choose something as a reason that makes you look sympathetic, for example, "I found out I like working on real world problems, more than on theoretical problems that have no connection to the way people actually interact with computers." I made that up -- it's just an example to give you an idea how it's possible to present oneself in a positive light.

Don't let them get the idea that you were extremely close to defending when you decided to leave, or that you failed the defense. Let them think that you broke up with your department, not that your department broke up with you.

But take the high road when speaking of your department. In other words, don't wash any dirty laundry in public. Don't say anything negative about the department or anyone in it. If they press you for more information, just go into broken record mode.

The easiest way to pull all of this off is to imagine that a year or two have gone by since you left the program, and you're talking to them about something that was a minor headline in last year's newspaper.

The question in the title is better than the specific one asked in the body of your post. (By better, I mean more in line with the aim of this site, as it is useful to many people in doctoral programs).

How to present ourselves to employers after a failed PhD is something many of us have pondered in moments of self doubt. To be clear, we are talking about truly failing (as determed by the committee/department/institution), not leaving for other reasons before finishing.

I think one possible spin to put on it, is that you've learned many, many skills and acquired a lot of knowledge over the course of your studies that will be useful in the workplace. The exact content of the dissertation itself may have been deemed inadequate or inappropriate for awarding the degree, but that does not mean that your knowledge and skills in the general field of study in which you were working are inadequate.

This argument is even stronger in an area like CS than it is in an area like (pure) math (for example). In math, to get a non-academic job I would push my research and writing skills. These skills would be hard to sell if I had failed my PhD. But in CS, you can get jobs based on things like programming skills that might be strong despite failing a thesis defense.

First of all, read the rules and procedures of your program carefully from start to finish. Don't make major life decisions over what you heard secondhand. For one thing, as others here, I am skeptical that you would leave empty-handed. Traditionally, failing a PhD means you get a Master's as a consolation prize and shown the door. Also note that you have rights beyond your department's decisions. They might want for their department to be special but it is generally not completely within their power to make up their own rules.

Second of all, if you do want to finish, it sounds like you are in good shape. "Borderline" is a positive answer to me, you have one foot in the winning side. You did produce papers, they just weren't accepted yet. Resubmit elsewhere. That count as publications "in process". Ask your committee what additional analysis will make your thesis passable. If you fail the defense, you can redo it after improvements. If you are not up against a hard graduation deadline you can continue trying. Remember research is a field that sometimes (often actually) required dogged tenacity.

Finally to actually answer your question, in industry they want to know your skills and accomplishments apart from the school graduation requirements (about which they care little). Without even a Master's you presumably aren't looking for research jobs. So they probably expect no more than a short resume (the rule of thumb used to be one page per ten years experience) which would devote a couple bullets tops to what you did in your years at school. E.g., used method A to address problem B.

As for interviews and generally framing things, you can tell them pretty much anything. Google around and you should find many good ideas. The critical thing is to be positive and avoid the appearance of being a quitter. For example, you decided research wasn't for you and you wanted to do "real work" (particularly the kind of work they do at the place who asked you the question). Or even just that you couldn't take being a starving student anymore. Or you didn't want to overspecialize your career in research. It's pretty easy to convince people who also didn't want a PhD, that you had a good reason for not wanting one yourself. This isn't really a question to ask academics, but industry professionals instead. Note that these answers are actually not lies, since you could have continued to work towards a doctorate if you really wanted to but are apparently deciding not to.