International Business Machines Corporation

Pradeep Kumar Nalla

Raj Kumar Gajavelly

Jason Raymond Baumgartner

Alexander Ivrii

Hari Mony

Robert Lowell Kanzelman

Rahul Rao

Anand Haridass

Arun Joseph

Ashutosh Misra

Raja Bilwakeshwar Ivaturi

Sujeet Kumar

Anand B Arunagiri

Dheeraj Baby

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

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

A computer-implemented method includes receiving a unit, wherein each unit includes one or more blocks. The computer-implemented method further includes selecting one or more input pins for each of said one or more blocks. The computer-implemented method further includes assigning a numerical value to each of said one or more input pins to yield at least one numerical sequence. The computer-implemented method further includes, for each numerical sequence of the at least one numerical sequence, performing a check on the numerical sequence to yield a number of fails. The computer-implemented method further includes determining a simulation condition for power modeling of the unit based on optimizing a numerical sequence with respect to the number of fails. The computer-implemented method further includes determining a number of design errors of the unit based on the simulation condition. A corresponding computer system and computer program product are also disclosed.

Formal verification driven power modeling and design verification

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

Disclosed aspects relate to verifying an integrated circuit design. A set of design constraints may be received with respect to a verification process for the integrated circuit design. Based on the set of design constraints, a constraint model may be constructed. A new global constraint may be determined using the constraint model. The new global constraint may be used to process the verification process for the integrated circuit design.

Integrated circuit design verification

A method includes configuring an integrated circuit comprising one or more registers to provide a free running clock in the integrated circuit, simulating N clock cycles in the circuit to provide performance results for one or more registers in the circuit, wherein N is a selected number of staging levels, selecting one of the one or more registers, comparing the performance results for the selected register to performance results for each of the remaining registers to provide one or more equivalent delay candidate registers, and verifying each of the one or more equivalent delay candidate registers to provide one or more confirmed equivalent delay registers. A corresponding computer program product and computer system are also disclosed.

Delayed equivalence identification

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

A computer program product includes program instructions to: Receive a unit including register transfer level content for a component of an integrated circuit and one or more IP blocks; Select one or more input pins for each IP block; Assign a numerical value of either zero or one to each of the one or more input pins to yield at least one numerical sequence; For each numerical sequence, perform a check to yield a number of fails, wherein the check is formal verification of each of the one or more IP blocks; Determine a simulation condition for power modeling of the unit based on optimizing a numerical sequence with respect to the number of fails; Set the one or more input pins to the simulation condition for power modeling of the unit; and Determine a number of design errors of the unit based on the simulation condition.

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Bengaluru, India

Pradeep Kumar Nalla