NextOp’s Assertion Synthesis – expanding ABV applications?

 

In case you missed it, read a user report on NextOp’s technology at: http://www.deepchip.com/items/0484-01.html 

In next couple of blog entries, I will share my reading, reflections on this detailed report.

To start with, this technology seems to address some of the “points to ponder” being discussed at: http://www.cvcblr.com/blog/?p=146 

As there is no whitepaper/material available on this technology I base my reflections solely on the ESNUG report. First thing that strikes me is, it seems to suggest in identifying “what assertions to write”. But then it takes a radically different approach to this problem atleast from what has been attempted so far by other EDA vendors. The single most difference is it takes the RTL + Testbench as guide to create assertions/properties. From the report:

 BugScope
takes in our RTL design and testbench as inputs and generates properties,
(which we then categorize as assertions or coverages) that help identify
bugs and coverage holes during simulation.  In contrast, Mentor's 0-in
assertion synthesis does not use our testbench; 

This is certainly new idea, though I’m little sceptical about the value of late-in-the-cycle assertions.

The next interetsing inference I have on this report is the “coverage property” generation:

When we began our BugScope eval, we only cared about assertion properties
it generated -- we didn't initially see any value of BugScope's coverage
properties.

From what I read in that report, its USP seems to be the “coverage holes” that it can identify. In which case it may be adding more work for the whole project than reducing it – true it helps with better quality, but folks like nuSym will go crazy to have more to cover, but again it is too early to comment in detail. The example given in that report looks little strange as that case maybe due to insufficient run-time of testcase, weak random generation, over-constrained stimulus etc. Also nowadays with RAL (VMM-RAL, www.vmmcentral.org) like automation, all registers can be captured in more controlled fashion from spec. So atleast I fail to see value with the example provided in the report. But since the user says he is using it in production for 2 years or so, there must be credit to this “niche technology”.

Perhaps NextOp is expanding the traditional ABV applications to include “verification closure requirements” by identifying what is not covered yet. That will be interesting application of ABV!

More on this report later.