Timing Window Segmentation for Gate-Level Netlist Optimization
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Solution Overview
Problem
Current integrated circuit design tools face inefficiencies in physical synthesis due to the high computational expense of querying timing conditions and updating edge values across the entire netlist, especially when only local changes are made, leading to unnecessary propagation and invalidation of timing information.
Innovation Solution
The approach involves creating a timing window representing a portion of the gate-level netlist for optimization, allowing for localized changes to be made and evaluated within this window, with checkpointing and transaction history management to assess and commit or revert changes efficiently, thereby reducing computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the entire gate-level netlist is queried for timing conditions and edge values are updated globally, then complete timing accuracy is maintained, but computational expense increases proportionally to the entire netlist size
Solution Approach 1:
The patent segments the gate-level netlist into distinct timing windows (first timing window and second timing window) that can be independently analyzed. When a change occurs in one timing window, only that specific window's timing conditions are re-evaluated rather than the entire netlist, reducing computational expense while maintaining timing accuracy for affected regions.
Solution Approach 2:
The patent applies local quality by making timing analysis adaptive to the location and scope of changes. The system identifies which specific timing windows are affected by a change and applies timing re-evaluation only to those localized regions, rather than uniformly processing the entire netlist, thus optimizing the balance between accuracy and computational cost.
2Stability of the object's composition
If timing information is propagated throughout the entire network after any change, then global timing consistency is ensured, but processing time increases
Solution Approach 1:
The patent divides the timing propagation process into segmented operations confined to specific timing windows. When a change occurs, timing information is propagated only within the affected timing window boundaries rather than forcing global propagation across the entire network, reducing processing time while maintaining consistency within the segmented regions.
Solution Approach 2:
The patent applies partial action by performing timing propagation only to the extent necessary - specifically, only to the timing windows that contain or are affected by changes. This avoids the excessive action of propagating timing information through the entire network when only local regions require updates.
3Loss of information
If the timing graph is fully updated with current timing conditions, then accurate timing information is available, but the overhead of maintaining and updating the entire graph increases computational cost
Solution Approach 1:
The patent segments the timing graph maintenance into window-specific operations. The timing graph is updated with current timing conditions only for the specific timing windows that have undergone changes, rather than maintaining and updating the entire graph, reducing computational overhead while preserving accuracy for affected regions.
Solution Approach 2:
The patent applies local quality by making timing graph updates adaptive to change locations. The system identifies which specific timing windows require graph updates and applies them locally, rather than uniformly updating the entire timing graph, thus optimizing the balance between information accuracy and synthesis efficiency.
Data Source
AI summary
A portion of a gate-level netlist representing an integrated circuit design is selected for optimization. A timing window representing the selected portion is made comprising one or more copies of the selected portion. A checkpoint is created for the timing window and stored in a transaction history. One or more changes are then made to the timing window and stored in the transaction history. The changed elements are marked as dirty and stored in the transaction history. After the one or more changes have been made, the timing window is queried for current timing conditions and compared with the checkpoint. If the one or more changes are an improvement, the one or more changes are committed by replicating the one or more changes to the portion of the gate-level netlist. If the one or more changes are not an improvement, the timing window may be restored to the checkpoint.