Standardized Functional Verification- P12:Every manager who brings a design to tape-out or who purchases IP must eventually face these questions. The ability to answer these questions based on quantitative analysis is both vital and yet elusive. In spite of the enormous technical advances made in IC development and verification software, the answers to these questions are still based largely on guesswork and hand waving. | Architecture for Verification Software 5 95 There is an implicit assumption underlying this strategy however that should be acknowledged when adopting it. This assumption is simply that the density of bugs is highest in the condensed space owing to the complexity associated with the logical decisions and computations made at these multi-dimensional vertices. Focusing simulation resources on the boundary values concentrates test generator power on the condensed space to ensure maximum likelihood of exposing bugs. Of course some useful fraction of verification resources should allocated to exploring the full uncondensed space as well. Experience and accumulation of empirical data will guide this allocation of simulation bandwidth. If certain functionality defined in the specifications seems to be buggier than other the rest of the target it may be advisable to focus test generation such that the VTGs derived from these specifications are more thoroughly or perhaps even exhaustively simulated. High coverage on known buggy areas can greatly reduce the risk of unexposed bugs in the related RTL. Sometimes it is necessary to modify tests to avoid generating faulty behavior due to known bugs. This can usually be accomplished by adjusting weights perhaps to zero for sub-ranges of variables on which the behavior is dependent thereby causing tests to be generated that test functionality unaffected by the known bugs. If this has been done then before closing out the bug report it is essential that any and all of these modifications be removed so that the functionality previously exhibiting faulty behavior can continue to be exercised. Architecture for Verification Software 5 The foundation of sturdy software architecture consists of well-defined data structures and that is where design of the verification software begins. 96 Chapter 4 - Planning and Execution Fig. . Architecting the test environment The architecture for the test environment . everything other .
