Callback Constraint Processing for IC Timing Analysis
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Solution Overview
Problem
Traditional methods for timing analysis in integrated circuit design face inefficiencies due to order dependency issues when loading and executing macros, leading to errors in timing analysis, especially when design changes affect clock distribution networks.
Innovation Solution
Implementing callback-based constraint processing, where timing abstracts are loaded but not immediately processed, and constraints are tagged as callbacks, allowing for selective re-application based on design changes that affect clock domains, ensuring clock domain independence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing constraints are processed immediately when loading timing abstracts, then processing order matters and errors occur, but processing efficiency is reduced due to re-computation requirements
Solution Approach 1:
The patent applies preliminary action by deferring constraint processing until all timing abstracts are loaded. Constraints are registered in advance but not executed until the timing graph is complete, preventing order dependency errors while avoiding redundant re-computations. This resolves the contradiction by preparing the processing framework early but delaying actual constraint application until the optimal moment when all data is available.
Solution Approach 2:
The patent implements dynamics by making the constraint processing timing flexible rather than fixed. Constraints are processed dynamically based on when they are most useful - after all relevant timing abstracts are loaded but before final timing analysis. This dynamic approach eliminates the need for strict processing order while maintaining efficiency by processing each constraint at the appropriate moment in the design hierarchy.
2Reliability
If all timing constraints are re-processed after design changes, then clock domain independence is maintained, but computational overhead increases
Solution Approach 1:
The patent applies segmentation by dividing constraint processing into separate callback functions associated with specific timing abstracts. When a design change occurs, only the affected callback segments are re-executed rather than all constraints. This segmentation maintains clock domain independence by ensuring proper constraint application while reducing re-computation time by limiting processing to only the necessary portions of the timing graph.
Solution Approach 2:
The patent implements local quality by applying constraints selectively based on their specific timing context and clock domain. Each callback processes only the constraints relevant to its associated timing abstract and clock domain, rather than globally re-processing all constraints. This localized approach preserves clock domain independence through proper constraint application while minimizing computational overhead by processing only locally affected constraints.
3Measurement precision
If timing analysis is performed at every hierarchical level, then comprehensive timing verification is achieved, but processing complexity increases
Solution Approach 1:
The patent applies the nested doll principle by implementing hierarchical constraint processing where timing abstracts are loaded and constraints are registered at multiple hierarchical levels (macro, unit, core). Constraints are processed in a nested manner from lower to higher levels, with each level's constraints being handled by appropriate callback functions. This nested approach achieves comprehensive timing verification across all hierarchical levels while managing processing complexity through structured organization and selective constraint application at each level.
Data Source
AI summary
A method, system and computer program product perform timing analysis of an integrated circuit design with callback-based constraint processing for clock domain independence. A timing graph representation of the integrated circuit design includes nodes interconnected by edges. Loading timing abstracts representing the nodes of the timing graph precedes obtaining a timing result based on propagating timing values and associated timing tags from an input to an output of the integrated circuit design and processing timing constraints at one or more of the nodes as callbacks. Each timing tag indicates a clock domain. After applying a design change, one or more modified timing tags that are added or changed as a result of the design change are determined. The timing constraints associated with the modified timing tags are processed as callbacks, and the timing result are re-computed.