Unreachability Analysis via Toggle Coverage Constraints
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Solution Overview
Problem
Current unreachability analysis tools in electronic design automation require substantial processing time due to the identification of viable targets as unreachable, leading to increased analysis time.
Innovation Solution
The method involves automatically generating constraints from toggle coverage reports to distinguish viable signals from dead code, reducing the number of processing steps required for unreachability analysis, and then performing a full analysis using these constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional unreachability analysis toolsteps are used to identify unreachable targets by analyzing toggle count data, then all possible unreachable targets including viable signals are identified, but the processing time is substantially increased
Solution Approach 1:
The patent applies preliminary action by generating constant signal constraints from toggle coverage reports before performing unreachability analysis. This pre-processing step identifies signals with zero or low toggle counts and creates constraints that exclude them from detailed analysis, thereby reducing the processing time while maintaining identification accuracy for actual unreachable targets
Solution Approach 2:
The patent extracts viable constant signals from the set of all possible unreachable targets by analyzing toggle coverage data. These extracted signals are then excluded from the main unreachability analysis through generated constraints, separating the analysis into two groups: constant signals (excluded via constraints) and potential unreachable targets (analyzed in detail), thus reducing overall processing time
2Reliability
If a large number of viable targets including constant input signals and OTP registers are analyzed for unreachability, then comprehensive coverage is achieved, but the number of processing steps and analysis time are substantially increased
Solution Approach 1:
The patent performs preliminary classification of signals by analyzing toggle coverage reports to identify constant signals and OTP registers before the main unreachability analysis. This preliminary action creates a filtered set of targets that requires detailed analysis, improving productivity while maintaining reliability through the subsequent generation of appropriate constraints
Solution Approach 2:
The patent segments the set of all targets into two distinct groups: constant signals (including OTP registers) identified from toggle coverage data, and other potential unreachable targets. This segmentation allows different analysis approaches to be applied to each group, with constraints generated for the first group and formal analysis applied to the second, thereby improving overall analysis throughput
Data Source
AI summary
An efficient unreachability analysis tool utilizes toggle coverage report data to automatically generate constraints associated with viable constant signals (e.g., constant inputs, one-time programmable and constant registers) utilized in a circuit design before performing a full unreachability analysis process, thereby improving the functioning of the computer/processor executing the unreachability analysis process by identifying low-activity registers and constraining them before the unreachability analysis process is performed, thereby substantially reducing the number of process steps required to identify dead code (unreachable signal/register targets). Constant inputs are identified using the toggle coverage report and used to generate corresponding constraints, and an initial unreachability analysis process is performed using only toggle coverage properties, then the full unreachability analysis process is performed for all (i.e., line, conditional, state/FSM and toggle) coverage properties using the constant input constraints. Constraints are also generated for one-time programmable and constant registers (OTP/C) before performing the full unreachability analysis process.