Add data flow analysis engine

[mathcelo]

Pull Request Title

Add data flow analysis engine with reentrancy detector

Description

PR introduces a general data flow analysis engine to Slither, along with a proof-of-concept reentrancy detector that demonstrates the engine's capabilities.

Summary

The existing reentrancy detector uses data flow in an ad-hoc manner specific to reentrancy detection. This contribution provides a general-purpose data flow analysis framework that can be extended for various static analysis techniques.

Key Changes

Data Flow Engine (slither/analyses/data_flow/engine/)

• engine.py: Core data flow analysis engine
• analysis.py: Analysis framework integration
• domain.py: Abstract domain definitions
• direction.py: Analysis direction support (currently forward analysis)

Proof of Concept Reentrancy Detector (slither/analyses/data_flow/analyses/reentrancy/)

• analysis/analysis.py: Data flow-based reentrancy analysis implementation
• analysis/domain.py: Domain-specific abstractions for reentrancy
• core/state.py: State representation for reentrancy analysis

Technical Implementation

• Integration: Uses SlithIR operations to determine program states
• Analysis Direction: Implements forward data flow analysis with capability for backward analysis
• Dependencies: Added loguru for logging purposes
• Compatibility: No modifications to existing Slither internals or breaking changes

Testing

• Copied existing reentrancy test cases to new test directory for the data flow-based detector
• Best test results observed with Solidity 0.8.0, with similar but not identical results for other versions
• New detector placed alongside existing detectors in standard location

Future Work

This engine provides the foundation for interval analysis (coming soon). The reentrancy detector is a proof of concept, not a production replacement.

Files Added

slither/analyses/data_flow/
├── analyses
│   └── reentrancy
│       ├── analysis
│       │   ├── analysis.py
│       │   └── domain.py
│       └── core
│           └── state.py
└── engine
    ├── analysis.py
    ├── direction.py
    ├── domain.py
    └── engine.py

Dependencies

• Added: loguru (for logging)

Backward Compatibility

No breaking changes. All existing functionality remains unaffected.

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