Detecting Dead Code

Dead Code Detection

Detection Workflow

1. Build call graph: Use disasm to build control flow, identify all functions, map function call relationships
2. Identify entry points: Find main/entry functions, locate exported functions, identify callback registrations, map interrupt handlers
3. Trace reachability: Perform forward reachability analysis from entry points, mark all reachable functions and blocks, identify unreachable code
4. Analyze dead code: Categorize dead code types, assess security implications, identify potential vulnerabilities, estimate size reduction

Key Patterns

• Unreachable functions: functions with no callers, functions only called from dead code, functions after infinite loops, functions after exit() calls
• Unreachable blocks: basic blocks after return statements, code after unconditional jumps, blocks with no incoming edges, code guarded by always-false conditions
• Unused data: global variables never referenced, string constants never used, data sections with no references, debug symbols in production builds
• Conditional dead code: code in always-false branches, debug-only code in release builds, platform-specific code for other platforms, feature flags permanently disabled

Output Format

Report with: id, type, subtype, severity, confidence, location, dead_code_type, reason, callers, references, size_estimate, security_implications, potential_vulnerabilities, recommendation.

Severity Guidelines

• MEDIUM: Dead code containing security vulnerabilities
• LOW: Dead code with no security impact

See Also

• patterns.md - Detailed detection patterns and exploitation scenarios
• examples.md - Example analysis cases and code samples
• references.md - CWE references and mitigation strategies

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