International Business Machines Corporation

Other

Jason Raymond Baumgartner

Hari Mony

Viresh Paruthi

Robert Lowell Kanzelman

Michael L Case

Geert Janssen

Steven Leonard Roberts

Pradeep Kumar Nalla

Raj Kumar Gajavelly

Nadeem Malik

Jiazhao Xu

Alexander Ivrii

Christian Jacobi

Kai Oliver Weber

Paul Joseph Roessler

Flemming Andersen

Wolfgang Roesner

Mark A Williams

Fadi A Zaraket

Kenneth Douglas Klapproth

Ali S El-Zein

Gabor Bobok

Raja Bilwakeshwar Ivaturi

Fadi Z Zaraket

Kenneth Lee Wright

Jun Sawada

Praveen S Reddy

Christoph Hermann Hagleitner

Ashutosh Misra

Tilman Gloekler

Ohad Shacham

Yee Ja

David Mui

Andreas Kuehlmann

Louise Helen Trevillyan

Nicolas Maeding

Kubilay Atasu

Tobias Gemmeke

Johannes Koesters

Ziv Nevo

Mitra Purandare

Bradley Donald Bingham

Sriram Srinivasan Mandyam

Steven Robert Farago

Robert James Ramirez

Robert Neill Newshutz

Matyas A Sustik

Arie Matsliah

Steven Mark German

Shaked Flur

Joachim Kneisel

Anita Devadason

Brett Adam St Onge

Claude Karl Detjens

Archie Don Barrett, Jr

Barinjato Ramanandray

Dheeraj Baby

Daniel Scott Heller

Anson Jeffrey Tripp

Rohit Dureja

Tamir Heyman

A method, a computer system, and a computer program product for detection of unintended dependencies between hardware design signals from pseudo-random number generator (PRNG) taps is provided. Embodiments of the present invention may include identifying one or more tap points in a design as an execution sequence. Embodiments of the present invention may include sampling the tap points by propagating the tap points in the design with different delays. Embodiments of the present invention may include defining observation points to identify tap collisions based on the tap points. Embodiments of the present invention may include identifying tap collisions. Embodiments of the present invention may include identifying one or more sources of the tap collisions in the design. Embodiments of the present invention may include eliminating the one or more sources of uninteresting tap collisions out of the tap collisions and filtering one or more of the tap collisions.

Detection of unintended dependencies in hardware designs with pseudo-random number generators

Invention disclosed herein is a method for performing connectivity verification of an integrated circuit device. In embodiments of the invention, the method includes creating a directed graph representation of the integrated circuit device. The method can further include determining target gates referred to as trace signals within the integrated circuit device. The method can further include creating a hierarchical representation of trace signals and determining nested trace signals. The method can further include determining one or more locations for cut points for non-nested trace signals. Thereafter, performing connectivity verification using the one or more locations for cut points. Finally improving scalability of the connectivity verification by utilizing hierarchical decomposition embodiment of the invention.

Scalable connectivity verification using conditional cut-points

Embodiments of the invention are directed to a computer-implemented method of logic verification. The method includes obtaining a netlist of a circuit comprising a plurality of observable gates. A first observable gate is grouped together with a second observable gate based on a portion of a fan-in logic of the first observable gate being equal to a portion of a fan-in logic of the second observable gate. The group is expanded by including a third observable gate, based on a first strongly connected component (SCC) in the group having a similarity greater than a first threshold to a second SCC in the fan-in logic of the third observable gate. The group is further expanded by including a fourth observable gate, based on the distance of a portion of the fan-in logic of the fourth observable gate from a fan-in logic of at least one observable gate in the group of observable gates.

Grouping and partitioning of properties for logic verification

A computing system determines a first set of registers having constant next-state functions in the netlist. The computing system identifies an observable gate in fan-out of a register in the first set, wherein an observable gate is a gate that is critical to a verification or synthesis context. The computing system identifies a second set of reducible registers in the fan-in of the observable gate. The computing system modifies at least one of an initial value and a next-state function of at least one reducible register of the second set to reflect an observable value of the at least one reducible register observed at the observable gate. The computing system simplifies one or more logic gates implementing the observable gate and the fan-in of the observable gate by eliminating a reference to a constant next-state function register in the first set of registers.

Initial-state and next-state value folding

A logic verification program, method and system provide an efficient behavior when verifying large logic designs. The logic is partitioned by cut-nodes that dominate two or more RANDOMS and a check is performed for a given cut-node to determine whether any of the dominated RANDOMS can be merged to a constant by performing satisfiability checks with each RANDOM merged to a constant, to determine whether a range of output values for the given cut-node has been reduced by merging the RANDOM. If the range is not reduced, the RANDOM can be added to the set of merge-able RANDOMS along with the corresponding constant value. If the range has been reduced, the opposite constant value is tried for a node and if the range is reduced for both constants, then the cut-node is abandoned for merging that dominated RANDOM and the next dominated RANDOM is tried.

Verification complexity reduction via range-preserving input-to-constant conversion

A computer implemented method for increasing scalability in bounded liveness verification includes receiving, by one or more processors, a counterexample trace showing a bounded liveness failure and a set of parameters associated with the counterexample trace, partitioning the counterexample trace into segments representing bound increments contributing to the bounded liveness failure, selecting, by one or more processors, a time interval during which to repeat input values, wherein the selected time interval correlates to one or more segments, evaluating, by one or more processors, the received counterexample after repeating the selected time interval, determining, by one or more processors, whether the evaluation indicates that the counterexample falsifies a deeper bound with respect to a bound or an unbounded liveness counterexample, and, responsive to determining the evaluation indicates that the counterexample falsifies a deeper bound, providing, by one or more processors, counterexample falsification results.

Scalable liveness verification

Aspects of the present invention include methods, systems and computer program products. The method includes a processor providing a netlist indicative of connectivity and functional states of components of an integrated circuit design; iteratively searching through the netlist at a selected depth to locate errors within the netlist by a plurality of trials, each of the plurality of trials having a plurality of iterations; adaptively adjusting the selected depth depending on any errors within the netlist being located, the selected depth increasing over time from an initial value as between the plurality of iterations; and adaptively adjusting an amount of coverage of the netlist depending on any errors within the netlist being located, the amount of coverage of the netlist decreasing over time from an initial amount as between the plurality of iterations.

Adaptive bug-search depth for simple and deep counterexamples

Embodiments herein describe a verification process that identifies unate primary inputs in input paths of a property gate. A property gate is logic inserted in a hardware design represented by a netlist which is used to verify the design. Before performing the verification process, a computing system evaluates the netlist to identify the primary inputs in the input paths of the property gate and whether these primary inputs are unate or binate. To do so, in one embodiment, the computing system sets the output of the property gate in an error state and then traverses the input paths of the property gate to identify the values of the logic in the inputs paths that would result in the property gate being in the error state. Based on these polarities, the system can identify the unate and binate primary inputs.

Scalable logic verification by identifying unate primary inputs

A trace of a bounded liveness failure of a system component is received, by one or more processors, along with fairness constraints and liveness assertion conditions. One or more processors generate randomized values for unassigned input values and register values, of the trace, and simulate traversal of each of a sequence of states of the trace. One or more processors determine whether traversing the sequence of states of the trace results in a repetition of a state, and responsive to determining that traversing the sequence of states of the trace does result in a repetition of a state, and the set of fairness constraints are asserted within the repetition of a state, and that the continuous liveness assertion conditions are maintained throughout the repetition of the state, a concrete counterexample of a liveness property of the system component is reported.

Lifting of bounded liveness counterexamples to concrete liveness counterexamples

A method for performing redundancy identification in an integrated circuit design. An optimized gate in a logic circuit is identified. A first netlist with a representation of the logic circuit is generated. An error is induced on the optimized gate. A second netlist is generated from a copy of the first netlist incorporating changes based on the error. Fan-out boundaries of the logic circuit are propagated for the first and second netlists. A redundancy report representing optimization steps performed to obtain the original logic circuit is analyzed to identify which steps are adequate to cause unobservability of the optimized gate. This is done by representing the optimization steps as constraints over the first and second netlists. Responsive to the error becoming undetectable under the constraints derived from the redundancy report, a minimal set of reductions is identified from the first netlist as the reason for unobservability of the optimized gate.

Scalable and automated identification of unobservability causality in logic optimization flows

Liveness verification of a logic design is performed using various shadow abstraction refinement techniques. An initial subset of state elements are included in the shadow abstraction, and verification is performed (liveness-to-safety conversion) using this initial subset. If a liveness counterexample is detected, the shadow abstraction is refined by designating a second subset of the state elements different from the initial subset for inclusion in a refined abstraction. The initial subset can be designated by choosing all registers in a combinational fan-in of a liveness property of the design. High-performance algorithms for abstract liveness-to-safety conversion can be based upon simulation and counterexample refinement, bounded model checking and counterexample refinement, bounded model checking and proof-based refinement, proofs obtained during bounded model checking of a precise liveness checking problem, a hybrid of counterexample-based refinement and proof analysis, and proofs obtained.

Method for scalable liveness verification via abstraction refinement

Growing community of inventors

Travis, TX, United States of America

Jason Raymond Baumgartner