Synopsys, Inc.

Kevin Michael Harer

Pei-Hsin Ho

Eduard Rudolf Cerny

Robert F Damiano

Ashvin Mark Dsouza

Mahesh A Iyer

Rajarshi Mukherjee

Kaushik De

In-Ho Moon

Narendra V Shenoy

Mahantesh D Narwade

Hi-Keung Tony Ma

Mandar Munishwar

Praveen Tiwari

Formal verification of connectivity of a circuit, for example, a circuit representing a system on chip I/O ring is performed with low power considerations. The formal verification determines whether the connectivity of a circuit remains valid when low power design specification is introduced. The system receives assertions representing connectivity of the circuit. The system receives low power design specification for a circuit that describes power states of power domains of the circuit. The system generates combinational constraints representing valid power states of power domains of the circuit. The system performs formal verification based on the assertions representing the connectivity of the circuit and the combinational constraints representing the power states of power domains of the circuit. The result of the formal verification is used to determine whether the connectivity of the circuit is valid in view of the low power design specification.

System on chip I/O connectivity verification in presence of low power design considerations

Verification-result ranking techniques for root cause analysis are disclosed using violation report analysis and violation weighting. Violation reports are unwieldy and result from a variety of design and process checks. The check coverage can overlap, causing a specific violation to trigger multiple reported violations. High turn around times for violation report analysis increase the risk that selective violation analysis will inadvertently suppress real design bugs. This reduces the odds that static checker reports alone will meet design sign-off criteria. Determining relationships among a plurality of violations for a design permits clustering violations into hot spots. Identification of primary and subsequent contributors to the plurality of violations is based on the relationships among violations. The hot spot with the highest weight is identified, and then subsequent violations are identified to maximize violation coverage. The result is greater efficiency of design violation identification and resolution.

Ranking verification results for root cause analysis

Some embodiments of the present invention provide systems and techniques for checking a livelock in a circuit design. During operation, the system can identify a finite state machine (FSM) in the circuit design, wherein the FSM comprises a first set of state variables. The system can then construct an abstract machine of the circuit design, wherein the abstract machine includes the FSM and a second set of state variables. Next, the system can search for one or more livelocks in the abstract machine. If a livelock is found in the abstract machine, the system can verify that the livelock is a livelock in a concrete machine of the circuit design, wherein the concrete machine includes the FSM and a third set of state variables, wherein the second set of state variables is a subset of the third set of state variables.

Abstraction-based livelock/deadlock checking for hardware verification

Relates to automatic conversion of assumption constraints, used in circuit design verification, that model an environment for testing a DUT/DUV, where the assumptions specify sequential behavior. Such assumptions are converted, with the use of logic synthesis tools, into a gate-level representation. For formal verification, a verification output is constructed from the gate-level representation and DUT/DUV assertion-monitoring circuitry. A formal verifier seeks to prove the verification output cannot indicate a design error. For simulation verification, the gate-level representation is converted into a hybrid representation comprising pipelines and combinational constraints. During simulation, the pipelines hold state information necessary for a solution, of the combinational constraints, to be in accord with the sequential assumption constraints. For certain sequential assumption constraints, the combinational constraints are insufficient to insure avoidance of deadend states. In a deadend state, an assumption is violated. A method is presented for augmenting the combinational constraints to avoid deadend states.

Method and Apparatus for Solving Sequential Constraints

One embodiment of the present invention provides a method and a system that facilitates structural coverage of a design during a design verification process. During operation, the system receives a hardware description of the design, which contains one or more module instances and a set of structural coverage targets for a set of structures in the design. The system then extracts a control flow, the set of structural coverage targets, and a set of structural coverage metrics for the hardware description, and creates a shadow module with the same control flow as the hardware description. This shadow module contains a set of parallel structures that correspond to the set of structural coverage targets in the control flow of the hardware description and serve as targets for formal methods used to analyze the design. The system also generates a set of cross-module references to link the set of parallel structures in the shadow module with signals from the set of structures in the hardware description. The system then applies a formal verification tool to the design, including the shadow module and the cross-module references in an attempt to achieve the desired structural coverage.

Facilitating structural coverage of a design during design verification

System, methods, and apparatus for verifying microcircuit designs by interleaving between random and formal simulation techniques to identify input traces useful for driving designs under test into sequences of device states. In a method aspect the invention provides process for beginning random simulation of a sequence of states of a microcircuit design by inputting a sequence of random input vectors to a design under test model in order to obtain a sequence of random simulation states; monitoring a simulation coverage progress metric to determine a preference for switching from random simulation to formal methods of simulating states in the design under test; beginning formal simulation of states in the design under test and monitoring a formal coverage progress metric to determine a preference for resuming random simulation of states of said microcircuit design; and resuming random simulation. Preferably the process of interleaving simulation methods continues until an input vector suitable for driving the design under test model into each of a set of previously-identified goal states has been obtained.

Simulation-based functional verification of microcircuit designs

Method and apparatus for solving sequential constraints

A process for synthesis and rough placement of an IC design. Initially, a synthesis tool is used to generate a netlist according to HDL, user constraint, and technology data. Each of the wires of the netlist is initially assigned a unit weight. Thereupon, a cell separation process assigns (x,y) locations to each of the cells based on the weights. The wires are then examined to determine their respective performance characteristics. The wires are iteratively re-weighted, and the cells moved according to the new weightings. Next, the cell location information is supplied to the synthesis tool, which can then make changes to the netlist thereto. In the present invention, the size of each of the gates can be either scaled up or down accordingly. Again, the nets are iteratively examined and their weights are adjusted appropriately. The cells are spaced apart according to the new weights.

Growing community of inventors

Cornelius, OR, United States of America

Kevin Michael Harer