SYSTEM AND METHOD FOR COMMON HISTORY PESSIMISM RELIEF DURING STATIC TIMING ANALYSIS

• US 20110035714A1
• Filed: 08/10/2009
• Published: 02/10/2011
• Est. Priority Date: 08/10/2009
• Status: Active Grant

• Current Assignee: Siemens Industry Software Limited (Siemens AG)
• Original Assignee: International Business Machines Corporation
• Inventors: Kalafala, Kerim, Soreff, Jeffrey P., Hathaway, David J., Foreman, Eric A., Hemmett, Jeffrey G., Habitz, Peter A.
• Granted Patent: US 8,141,014 B2
• Time in Patent Office: Days
• US Class Current: 716/108
• CPC Class Codes: G06F 2119/12 Timing analysis or timing optimisation
• CPC Class Codes: G06F 30/3312 Timing analysis

Abstract

A system and method for adjustment of modeled timing data variation as a function of past state and/or switching history during static timing analysis. One illustrative embodiment may include inputting and asserting at least one of initial signal history bound and explicit device history bound constraints for at least one signal of a circuit design and evaluating for a segment processed during a forward propagation of block based static timing analysis whether any input signal to a current segment has a bounded history, at least one of propagated and asserted. The method may further include evaluating for the segment whether history bounds are downstream from a gating restriction, and processing a next segment until there are no further segments.

Claims

10. A program product stored on a computer readable medium, which when executed, adjusts modeled timing data variation as a function of past state and/or switching history during static timing analysis, the program product comprising:

program code for at least one of inputting and asserting at least one of initial signal history bound and explicit device history bound constraints for at least one signal of a circuit design;

program code for evaluating for a segment processed during a forward propagation of block based static timing analysis whether any input signal to a current segment has a bounded history, at least one of propagated and asserted;

program code for evaluating for the segment whether history bounds are downstream from a gating restriction; and

program code for processing a next segment until there are no further segments.

11. The program product of claim 10, further comprising program code for propagating the history bounds without a gating restriction in response to the history bounds not being downstream from the gating restriction.

12. The program product of claim 10, further comprising program code for proceeding directly to the processing of the next segment in response to the current segment not having a bounded history.

13. The program product of claim 10, further comprising program code for proceeding directly to the processing of the next segment in response to the current segment not having a bounded history.

14. The program product of claim 10, further comprising program code for propagating the history bounds with a gating restriction in response to the history bounds being downstream from the gating restriction,.

15. The program product of claim 10, further comprising program code for performing a generalized common path pessimism removal (gCPPR) processing.

16. The program product of claim 15, wherein the program code for gCPPR processing includes program code for canceling at least a portion of a history component in a test where both sides of the test are found to share a common bound and gating restriction.

17. The program product of claim 10, further comprising program code for performing a statistical static timing analysis (SSTA) slack evaluation process.

18. The program product of claim 17, wherein the program code for the SSTA slack evaluation includes program code for processing history based parameters, wherein the parameters with common history bounds and gating restrictions are at least partially canceled during slack calculations.

19-1. The system of claim 20, wherein the static timing engine is further structured to proceed directly to the processing of the next segment in response to the current segment not having a bounded history.

20-2. The system of claim 20, wherein the static timing engine is further structured to propagate the history bounds without a gating restriction in response to the history bounds are not downstream from the gating restriction.