Compiler Debug Annotation for Accurate Variable Tracking
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Solution Overview
Problem
Compilers face challenges in retaining accurate debug information for user variables due to optimization passes, leading to incomplete or incorrect location information, resulting in increased memory consumption and CPU overhead.
Innovation Solution
The introduction of debug annotations, specifically debug temporaries, which replace statements optimized away and are referenced in subsequent debug expressions, preventing exponential growth of debug expressions and maintaining accurate location information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compiler optimization passes are increased to improve compilation efficiency, then productivity is improved, but debug information accuracy deteriorates
Solution Approach 1:
The patent introduces debug temporaries as intermediary constructs that mediate between optimized code and debug information requirements. These debug temporaries serve as placeholders that preserve variable location information through optimization passes while not interfering with the optimized code structure. The debug temporary acts as a mediator that allows the compiler to perform aggressive optimizations while maintaining the ability to emit accurate debug information.
2Measurement precision
If debug expressions are expanded to maintain accurate variable location tracking, then measurement precision is improved, but memory consumption increases
Solution Approach 1:
The patent segments debug information generation into multiple phases: (1) inserting debug temporaries at statement boundaries during optimization, (2) performing optimizations that may remove or move statements, and (3) emitting debug information that references the debug temporaries. This segmentation allows the compiler to maintain accurate variable location tracking without expanding debug expressions in memory simultaneously, as debug temporaries serve as compact references throughout the optimization process.
3Reliability
If debug expressions are expanded to track optimized-away variables, then reliability of debug information is improved, but CPU overhead increases
Solution Approach 1:
The patent performs preliminary insertion of debug temporaries into the intermediate representation before optimization passes occur. This preliminary action ensures that variable location information is captured at the appropriate points in the compilation process, allowing the compiler to subsequently optimize away statements while preserving debug information through the debug temporary references. This eliminates the need for CPU-intensive post-optimization analysis to reconstruct debug information.
Data Source
AI summary
A method and system for improving debug information pertaining to user variables using a compiler. The method may include identifying a statement to be removed from its current position in an internal representation of a program by a compiler as part of the compiler optimization, replacing the statement to be removed with a debug annotation, adding references to the debug annotation in subsequent debug expressions referring to the removed statement, and emitting debug location information for a user variable using the debug annotation.