Coverage-based test generation for microprocessor verification

• US 6,647,513 B1
• Filed: 05/25/2000
• Issued: 11/11/2003
• Est. Priority Date: 05/25/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hekmatpour, Amir
• Primary Examiner(s): Iqbal, Nadeem
• Assistant Examiner(s): Bonura, Timothy M
• Application Number:
  US09/578,743
• Time in Patent Office: 1,265 Days
• Field of Search: 714/39, 714/41, 714/37, 714/32, 714/25, 714/47, 714/33
• US Class Current: 714/37
• CPC Class Codes: G06F 11/263 Generation of test inputs, e.g. test vectors, patterns or sequences ; with adaptation of the tested hardware for testability with external testers

Abstract

An integrated circuit verification method and system are disclosed. The method includes generating a test description comprising a set of test cases. The functional coverage achieved by the test description is then determined. The functional coverage achieved is then compared against previously achieved functional coverage and the test description is modified prior to simulation if the test description achieves no incremental functional coverage. In one embodiment, generating the test description comprises generating a test specification and providing the test specification to a test generator suitable for generating the test description. In one embodiment, the test description comprises a generic test description and the generic test description is formatted according to a project specification and simulation environment requirements. If the coverage achieved by the test description satisfies the test specification. In one embodiment, the functional coverage achieved by the test description is displayed in a graphical format. The test description is preferably added to a test database if the coverage achieved by the test description satisfies the test specification. The attributes and description of functional coverage achieved is added to the coverage database. Determining the functional coverage achieved by a test description may include estimating the coverage achieved based upon the test description, the test specification, and functional coverage model.

Claims

1. A verification method, comprising:

generating a first test description, simulating the first test description, and storing functional coverage information derived therefrom in a functional coverage database;

generating a second test description;

determining the functional coverage achievable by the second test description;

comparing the functional coverage achievable by the second test description against the functional coverage information stored in the functional coverage database;

modifying the second test description prior to simulating it if the second test description achieves no incremental coverage; and

simulating the second test description if the functional coverage achievable by the second test description exceeds the functional coverage stored in the database and storing information indicative of the functional coverage achieved by said simulating in the database.

2. The method of claim 1, wherein generating the second test description comprises generating a test specification and providing the test specification to a test generator suitable for generating the test description.

3. The method of claim 2 wherein the second test description comprises a generic test description.

4. The method of claim 3, wherein the generic test description is formatted based on a project specification if the coverage achieved by the second test description satisfies the test specification to produce a formatted test description suitable for simulation, in a specific verification/simulation environment.

5. The method of claim 1, further comprising graphically displaying the functional coverage achieved by the second test description.

6. The method of claim 1, further comprising adding the second test description'"'"'s corresponding coverage attributes to the functional coverage database if the coverage achieved by the second test description satisfies the test specification.

7. The method of claim 1, wherein determining the functional coverage achieved comprises estimating the coverage achieved based upon a generic test description, the test specification, and a design architecture specification comprising a functional and coverage model.

8. A system for generating a test description for use in verifying an integrated circuit design, comprising:

a test generator suitable for receiving a test specification and generating a test description responsive thereto;

a coverage estimator adapted to generate a test coverage model indicative of the functional coverage achievable by the test description; and

a test coverage analyzer configured to analyze the test coverage model corresponding to a test description and to compare the estimated coverage against a coverage database storing functional coverage information indicative of functional coverage achieved during simulation of a prior test description;

an optimizer to modify the test description prior to simulating it if the test description does not achieve functional coverage in excess of the functional coverage in the database; and

means for simulating the test description if the test description achieves functional coverage in excess of the functional coverage and for storing the information indicative of the functional coverage achieved therefrom in the database.

9. The system of claim 8, wherein the optimizer is configured to receive a test specification and adapted to produce an optimized test specification based on a project specification and simulation environment requirements.

10. The system of claim 9, wherein the optimized test specification is adapted to produce a test description that achieves functional coverage of the integrated circuit that is equal to or greater than the functional coverage achieved by the non-optimized (original) test description.

11. The system of claim 8, wherein the test generator generates a pseudo random generic (format) test description according to specified test specification, biases and its corresponding coverage attributes.

12. The system of claim 11, further comprising a formatter adapted to convert the generic test description based on project specification information and the simulation environment requirements.

13. The system of claim 8, wherein the coverage estimator receives a rule base indicative of a mapping between a test specification and a coverage mapping and wherein the coverage estimator utilizes the rule base to map the generic test description to a set of coverage states.

14. A data processing system comprising a processor, a storage device, input means, and a display, the storage device configure with a set of instructions executable by the processor, the set of instructions comprising:

test generator means for generating a test description from a test specification;

coverage estimator means for determining the functional coverage achievable by the test description;

means for comparing the functional coverage achievable by the test description against functional coverage information stored in a functional coverage database and indicative of the functional coverage achieved by simulation of a prior test description;

means for modifying the test description prior to simulating the test description if the test description achieves no incremental coverage; and

means for simulating the test description and for storing functional coverage information derived therefrom in the functional coverage database.

15. The system of claim 14, wherein the test generator means comprises means for generating a test specification and means for providing the test specification to a test generator suitable for generating the test description.

16. The system of claim 15 wherein the test description comprises a generic format test description.

17. The system of claim 16, wherein the generic test description is formatted based on a project specification if the coverage achieved by the test description satisfies the test specification to produce a formatted test description suitable for simulation.

18. The system of claim 14, further comprising graphically displaying the functional coverage achieved by the test description.

19. The system of claim 14, further comprising adding the test description to a coverage database if the coverage achieved by the test description satisfies the test specification.

20. The system of claim 14, wherein determining the functional coverage achieved comprises estimating the coverage achieved based upon the generic test description, the test specification, and a design architecture specification comprising a functional coverage model of integrated circuit.