The ESL Edge

At DAC, I missed an appointment with a company CEO. While I had excuses, at the end of the day I just blew it. Many CEO’s would have said, you had your chance and lost it, but not Tom Sandoval at Calypto. He hardly seemed bothered, or at least did not show it when I turned up to apologize. Since neither of us had any additional free slots during DAC, we arranged to talk after DAC. It would have been very simple for them to just forget. But some companies have blood hounds for their PR agencies and in this case Diane Orr was not going to let the opportunity slip away. So thanks to both of them at the outset for treating a member of the blogosphere with such respect. Of course that is not going to buy them any favors! I will still write what I believe needs to be written, but in this case they have nothing to worry about.

Tom and I talked for well over an hour on the phone, with presentations that had been sent to me in advance and with WebEx for some more detailed technical information. At no point in the discussion did Tom appear to evade any of my questions or have anything to hide. I was also amazed at how well he conveyed the technical concepts. Most CEOs would have clammed up and said nothing in response to some of the questions I asked, but Tom gave me thoughtful answers and we exchanged ideas on things that I think are only suitable for EDA gossip rags. This is not one of them!

What we did talk about was the strategy for the company and how it seemed to have changed over time. Calypto made a big splash at DAC 2005 with their sequential equivalence checking product (SLEC). Their booth was so packed at this show, that some of the nearby vendors were grumbling that people could not get to their booth, or that other people had to walk through their booth because the isles were too congested. Of course it could have been something to do with the stuffed toys they were giving away, but more likely it was one of those rare times when a completely new tool concept was shown for the first time. It seemed to come out of nowhere. Everyone wanted to know what it was. But a product such as SLEC is dependent on a vibrant high-level synthesis (HLS) market, which if you will remember back in 2005 was not really in place. Hmmm – sounds like a product ahead of its time.

But now in 2009 HLS is taking off and sales are ramping quite fast, and with Cadence being the new entrant on the block, it is now seeing quite a product battle raging between them, Mentor and Forte. Of course we should not forget Bluespec as well, but they are in a somewhat different class than the rest – but that is for another posting. All three of these HLS vendors have a close working relationship with Calypto, as they all depend on them to some extent. As Tom put it, equivalence checking is still finding problems with RTL synthesis tools and the bug rates for HLS are a lot higher given the rate at which this technology is advancing.

So with the HLS market catching up with them at last, it seemed strange to me that they were broadening their product line with some RTL optimization tools – particularly in the power optimization space. Tom told me that the early founders of the company had always wanted to do a system level power optimization tool, but that at the time they felt the market for this was even smaller than for SLEC (I can image these were not quite the same talks and messages that they gave to their early investors). He also provided an interesting twist on this that I hadn’t thought of. When Synopsys first came out with a logic equivalence checker, it was met with a high degree of skepticism. Was it the fox guarding the hen house? Weren’t they going to make the same mistakes in their equivalence checker that they made in the synthesis tool? So Calypto wanted to make a name for itself in verification first and then use some of the same technology to build design tools. Tom reminded me that the RTL market is a LOT larger than the HLS market and will be for quite a long time, and thus tools that work at the RTL level are likely to deliver them with more immediate gains, but that sequential equivalence checking remains a core technology on top of which they will continue to develop other products.

With most of the HLS vendors relying on Calypto to provide the sequential equivalence checking, I asked Tom how long he thought it would be before one of them bought his company. At that he chuckled and said I should ask them, but he did not appear to be too uncomfortable about the position he is in. I would imagine Mentor, Cadence and Forte would not feel quite so comfortable if one of them made a move and left the others out in the cold. I am taking bets now as to who will be the first to move.

The next question I had for Tom, was one I was sure he would punt on. I asked whether he saw more opportunities based on C, C++ or SystemC? While he did not say that he favored any one of them, he said that performing equivalence checking on SystemC tended to be easier because it was often closer to the RTL and that finding the right match points was relatively straight forward. With the tools based on C or C++ (or for that matter an early C description that is refined into SystemC), there were additional opportunities for doing C to C equivalence checking, when for example floating point to fixed point transformation are made, or other architectural changes are made. It is important at that stage to ensure that the functionality has not been compromised.

That seemed to me to be a huge challenge, so I asked Tom how much manual intervention was necessary in order to compare at this level of abstraction. He said that their goal is for it to be completely automatic, but with large designs or complex interconnect at the architectural level some manual intervention may be required. There is some information that is passed from the HLS tool to SLEC that helps it find the right match points, but even when these are provided, the first thing they have to do is to verify that this is indeed true, otherwise all of the rest of their analysis may be based on false information. When the HLS tool vendors implement new optimization strategies, they do not always provide this help in the first release, and then more manual work is required, but as the optimization matures, then these hints are provided. I was surprised to hear that Calypto has almost weekly calls with each of the HSL vendors to ensure that the tools are kept in sync as much as possible.

At this point in the conversation, we switched over to more technical discussions about the tools themselves, and I will be reporting on that at another time.

So thanks Tom and Diane. These are the kind of calls that provide me with the information I need to do my job.

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Brian Bailey – keeping you covered.

brian_bailey at acm.org