March 26, 2012 -- Avery Design Systems, Inc. has announced availability of its SimXACT X-verification solution, targeting comprehensive X-propagation analysis including gate-level X-pessimism analysis and automatic correction of gate-level simulation results, and XVER for X optimism analysis of RTL simulation.
The inherent limitations of handling non-determinism associated with X values in logic simulation means simulation results may not reflect actual hardware operation. Insight XVER uses formal methods to accurately analyze X propagations enabling engineers to:
- Run gate-level simulations free of X-pessimism issues.
- Diagnose occurrences of X optimism in RTL simulations alerting designers who may be unaware of potential non-deterministic sequential behaviors-
- Perform sequential X-propagation forward and backward tracing and debug.
- Accurately analyze and report X states during hardware-reset and power-transition sequences to confirm design specs.
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SimXACT utilizes a hybrid method to perform formal combinatorial X-pessimism analysis while running gate-level simulation of a full chip netlist. SimXACT supports Cadence NC-Sim, Synopsys VCS, and Mentor Questa. When an X is encountered during simulation at a register/ latch input or chip-level output, SimXACT formally proves whether the X is real or false. If false, Insight applies its patent-pending technology to dynamically correct the simulation value on the fly in the simulator as well as generates HDL code pinpointing a force/ release at the origin of the X pessimism. The set of HDL fixes can be used for subsequent simulations which run at their native, full simulation speed and are free of X pessimism.
SimXACT also identifies clocking issues associated with internal clock generators and gated clocks and generates forces for them. Real X propagation can be debugged using a full sequential backtrace report showing the exact register to register paths from original X source registers or inputs to their destination registers spanning multiple clock cycles.
"Developing manual force/release fixes or applying random 0/1 deposit to registers at X are less than ideal solutions because bugs may be masked," saidd Chilai Huang, President of Avery. "SimXACT has been used to analyze and correct chip-level simulations in just a few hours which involved 100s of X-pessimism occurrences and is guaranteed not to mask any bugs. SimXACT improves design reliability and the automated process eliminates schedule risk during chip sign-off." .
XVER supports formal sequential X propagation analysis at the RT-level including X optimism analysis of RTL simulations. Here XVER performs symbolic simulation of actual simulation testcases and analyzes them for the presence of X optimism which will result in non-deterministic sequential design operation. A full sequential backtrace report is generated showing the exact RTL path from original X source registers or inputs to their destination registers spanning multiple clock cycles. Designers can then confirm whether the X propagations are acceptable, eliminate undesirable X sources, or make their design more tolerant of handling the non-determinism. RT-level analysis helps resolve X issues that currently may not be found until gate-level simulation is run.
SimXACT and XVER are part of the Insight product family of innovative automatic formal solutions including:
- PSYN - Automatic microarchitecture-level property and coverage synthesis addressing the needs of RTL designers to improve baseline coverage metrics and their use of assertion-based verification methods.
- DFT - RT-level at-speed DFT testability analysis and automated testpoint insertion to improve small delay defect, transition delay fault (SDD-TDF) and path delay fault scan-based test coverage prior to running ATPG.
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Go to the Avery Design Systems, Inc. website to find additional information.
