Compiler Contract Preservation for Error Handling
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Solution Overview
Problem
Traditional software systems combine different types of error conditions into a single mechanism, making it difficult to simulate and test error recovery, leading to compound errors and crashes due to improper error recovery logic.
Innovation Solution
A front-end compiler compiles source code into intermediate code with contract checks that conditionally execute execution scopes based on predicate validity, allowing for semantic preservation and analysis by static tools, enabling fail-fast mechanisms and optional external error recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional software systems use a single uniform mechanism for all error conditions, then the system maintains simplicity and consistency in error handling, but this obfuscates qualitative differences in errors and makes it difficult to simulate and test error recovery
Solution Approach 1:
The patent segments error conditions into different types (runtime errors, contract violations, assertion failures) with distinct handling mechanisms. Each error type has its own representation and recovery strategy, allowing targeted simulation and testing while maintaining overall system structure.
Solution Approach 2:
Different error conditions are treated with locally appropriate quality - each error type receives specialized handling tailored to its specific characteristics. Contract violations use contract checking mechanisms, runtime errors use exception handling, and assertion failures use verification mechanisms, rather than a single uniform approach.
2Reliability
If error recovery logic is included in the execution scope, then the program can handle errors internally, but this leads to compound errors and crashes when error recovery logic itself fails
Solution Approach 1:
The patent extracts error recovery logic from the main execution scope into separate error handling mechanisms. Contract checks, assertions, and error handlers operate as distinct entities that can be independently validated and tested, preventing compound errors while maintaining error recovery capabilities.
Solution Approach 2:
Error conditions are checked and validated before execution proceeds - contract preconditions are verified before method calls, assertions are checked before critical operations. This preliminary validation prevents errors from propagating and causing compound failures.
3Productivity
If contract checks are removed from intermediate code to improve compilation speed, then compilation efficiency increases, but static analysis tools lose the ability to perform intelligent analysis and optimization
Solution Approach 1:
The patent introduces an intermediary representation in the intermediate code that preserves contract semantics in a form suitable for both fast compilation and static analysis. Contract information is encoded in a way that allows compilers to process efficiently while enabling static analysis tools to perform intelligent optimization.
Solution Approach 2:
The intermediate code uses specialized parameters and metadata to represent contract conditions, allowing the compilation process to optimize based on contract information without requiring full semantic interpretation. This enables both speed and analysis capability.
Data Source
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Figure 3A~3B
AI summary
A front-end compiler compiles source code into intermediate code, that may later be compiled into binary code. The source code defines an execution scope and includes a contract. When a contract is encountered at runtime of an execution scope, further execution of that execution scope is conditioned on whether a predicate associated with the contract is true. The front-end compiler operates so as to preserve the contract so that the contract continues to be semantically structured such that the predicate may be removed from the intermediate language code. The contract may thus continue to be understood by semantic analysis of the contract. Thus, the predicate may be understood by static analysis tools that operate on the intermediate code.