International Business Machines Corporation

Peihua Qi

Kerim Kalafala

Chandramouli Visweswariah

David James Hathaway

Eric A Foreman

Peter Anton Habitz

Nathan C Buck

John P Dubuque

Xiaoyue X Wang

Vladimir P Zolotov

Mark Alan Lavin

Jeffrey G Hemmett

Natesan Venkateswaran

Alexander Joel Suess

Jennifer E Basile

A method of applying common path credit in a static timing analysis in the presence of correlations between asserted arrival times, comprising the steps of using a computer, identifying one or more pairs of asserted arrival times for which one or more correlations exist; propagating to each of the one or more pairs of asserted arrival times a timing value dependent on the one or more correlations; and performing a subsequent common path pessimism removal analysis for at least one test during which a timing value dependent on the one or more correlations between asserted arrival times is used to compute an adjusted test slack.

System and method for performing static timing analysis in the presence of correlations between asserted arrival times

A method for efficient multithreaded analysis of a timing graph is described. The method is applicable to multithreaded common path pessimism removal, critical path traversing for timing report generation, and other types of analysis requiring traversal of sub-graphs of timing graph. In order to achieve high efficiency and scalability for parallel multithreaded execution, the number of access locks is minimized. One parent computation thread and multiple child threads are employed. The parent computational thread identifies the tasks for analysis and distributes them among child threads. Each child thread identifies a sub-graph to be analyzed, creates a thread-specific replica of the identified sub-graph, and performs the analysis required. After completing the analysis, the child thread transfers the results back to the main timing graph and waits for next task. As all data structures of each child thread are accessed only by the child thread owing them, no access locks are required for construction and processing of thread specific graph replica of the timing sub-graph. The construction of each thread specific graph replica is performed by the child thread without locking the main timing graph data structures. Access locks are used only for transferring results of the analysis back to the main timing graph where the results computed by all child threads are combined together.

Method for performing a parallel static timing analysis using thread-specific sub-graphs

A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing. In one example, a decreasing parameter order is utilized to order slack cutoff values that are assigned across a parameter process space. In another example, a decreasing parameter order is utilized to perform a multi-corner timing analysis on one or more dependent parameters in an independent fashion.

Parameter ordering for multi-corner static timing analysis

A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, slack cutoff values are assigned across a parameter process space. For example, a slack cutoff value is assigned to each parameter in a process space by determining an estimated maximum slack change between a starting corner and any other corner in a corresponding process sub-space. In another embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing.

Variable threshold system and method for multi-corner static timing analysis

Methods, systems and computer program products for analyzing a timing design of an integrated circuit are disclosed. According to an embodiment, a method for analyzing a timing design of an integrated circuit comprises: providing an initial static timing analysis of the integrated circuit; selecting a static timing test with respect to a static timing test point based on the initial static timing analysis; selecting a timing path leading to the static timing test point for the static timing test; determining an integrated slack path variability for the timing path based on a joint probability distribution of at least one statistically independent parameter; and analyzing the timing design based on the integrated slack path variability.

Method and system for evaluating statistical sensitivity credit in path-based hybrid multi-corner static timing analysis

A method of removing pessimism in static timing analysis is described. Delays are expressed as a function of discrete parameter settings allowing for both local and global variation to be taken in to account. Based on a specified target slack, each failing timing test is examined to determine a consistent set of parameter settings which produces the worst possible slack. The analysis is performed on a path basis. By considering only parameters which are in common to a particular data/clock path-pair, the number of process combinations that need to be explored is reduced when compared to analyzing all combinations of the global parameter settings. Further, if parameters are separable and linear, worst-case variable assignments for a particular clock/data path pair can be computed in linear time by independently assigning each parameter value. In addition, if available, the incremental delay change with respect to each physically realizable process variable may be used to project the worst-case variable assignment on a per-path basis without the need for performing explicit corner enumeration.

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Wappingers Falls, NY, United States of America

Peihua Qi