Path-Sensitive Data-Flow Analysis for Software Error Detection
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Solution Overview
Problem
Current program analysis methods are inadequate in detecting errors, particularly use-after-free defects, due to their lack of path-sensitivity, leading to false positives and unreported errors in software development.
Innovation Solution
A path-sensitive data-flow analysis method is introduced, which identifies instructions connected by multiple control flow paths, defines a complex disjunction of predicates as a path condition, converts it into conjunctive normal form, simplifies the condition, and uses it to detect errors, thereby enhancing the accuracy of error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current program analysis methods are used, then the analysis process is simple, but error detection precision is low leading to false positives and unreported errors
Solution Approach 1:
The patent segments the analysis by introducing path conditions that divide the control flow into distinct paths between instructions. Each path is analyzed separately with its own condition, allowing precise tracking of which path is being evaluated. This segmentation enables the system to handle complex multi-path scenarios while maintaining manageable analysis complexity through systematic breakdown.
Solution Approach 2:
The patent adds a new dimension to traditional program analysis by incorporating path conditions as an additional analytical layer. Instead of only analyzing data flow in the traditional control flow graph dimension, the system now operates in a enhanced dimension that includes path condition satisfaction, enabling more precise error detection without proportionally increasing overall complexity.
2Measurement precision
If path-sensitive analysis with multiple control flow paths is implemented, then error detection precision improves, but the complexity of defining and managing path conditions increases
Solution Approach 1:
The patent applies preliminary action by pre-defining path conditions for each control flow path before analysis begins. The system establishes the logical conditions that must be satisfied for each path to be taken, and these pre-computed conditions are then reused throughout the analysis process. This preliminary preparation reduces the complexity of managing path conditions during actual error detection.
Solution Approach 2:
The patent introduces path conditions as intermediary elements that mediate between the control flow graph structure and the error detection logic. These path conditions act as intermediaries that capture the essential constraints of each path without requiring the full complexity of the control flow to be managed directly by the error detection algorithms, thereby reducing overall system complexity.
3Measurement precision
If complex disjunction of predicates is converted to conjunctive normal form and simplified, then analysis precision improves, but the processing time and computational complexity increase
Solution Approach 1:
The patent applies partial action by selectively converting path conditions to conjunctive normal form only when necessary for precise error detection, rather than universally applying the transformation to all conditions. The system performs simplification operations on a partial basis, focusing computational effort on critical paths and conditions where precision is most valuable, thereby reducing overall processing time while maintaining necessary precision.
Data Source
AI summary
A method for performing path-sensitive data-flow analysis for use in error checking functions includes identifying at least a first instruction and a second instruction in a control flow graph of a function. The identified first instruction and second instruction are connected by at least a first control flow path and a second control flow path. The method further includes defining a path condition between the first instruction and the second instruction as a complex disjunction including a first conjunction of predicates for the first control flow path and a second conjunction of predicates for the second control flow path. The method further includes converting the path condition into conjunctive normal form to obtain a converted path condition that includes a disjunction of atomic constraints, generating a simplified path condition by simplifying the disjunction of atomic constraints in the converted path condition to a value, analyzing the function using the simplified path condition to detect an error, and presenting the error.