Published
Jun 5, 2024
Updated
Jun 5, 2024

Can LLMs Build Verified Code Transpilers?

Verified Code Transpilation with LLMs
By
Sahil Bhatia|Jie Qiu|Niranjan Hasabnis|Sanjit A. Seshia|Alvin Cheung

Summary

Imagine effortlessly converting code between languages with guaranteed accuracy. That's the promise of verified code transpilation. But traditional methods are complex and often require extensive manual effort. This post explores how Large Language Models (LLMs) are revolutionizing this field, potentially automating the process of creating these powerful transpilers. Traditionally, transpilation involves converting code from a source language to a target language, and verifying its correctness using a process called verified lifting. This process involves defining an intermediate representation (IR) of the target language's operators, translating the source code into this IR, and finally proving the functional equivalence of the translated code and the original source code. This verification step, while crucial for guaranteeing correctness, adds significant complexity to building transpilers. The innovation explored in this research leverages LLMs to simplify this process. By treating Python as an intermediate representation, LLMs can be prompted to translate code into this readily understandable language. This avoids the problem of LLMs struggling with the nuances of lesser-known domain-specific languages (DSLs). Python is also well-represented in the training data of many LLMs, enabling them to translate and reason effectively. The LLM-based approach, known as LLMLIFT, involves two phases: program summary (PS) generation and invariant generation. The PS summarizes the source program using DSL operators within the Python IR. Invariants, which are logical assertions about the program's behavior, help verify the equivalence of the summary and the original code. This approach was tested on four different DSLs: Apache Spark for distributed computing, network packet processing languages, and two tensor processing languages. The findings are remarkable. LLMLIFT not only achieved comparable or better performance in successfully transpiling code than existing symbolic solvers but also did so with dramatically reduced manual effort. It solved more benchmarks faster, and reduced the lines of code required for tool development by a factor of 1000 in some cases. In one case involving tensor processing, LLMLIFT solved all 60 benchmarks compared to 57 solved by a traditional solver, even handling more complex expressions that stumped existing tools. While LLMLIFT represents a considerable advance, challenges remain. LLMs can sometimes generate syntactically or semantically incorrect Python code, requiring a parser to validate the output. Further research is needed to refine the approach for even greater efficiency and reliability. Nonetheless, the implications are exciting. LLMLIFT has the potential to automate the construction of verified transpilers, enabling developers to easily and reliably port code to specialized hardware and benefit from DSL optimizations without arduous manual translation and verification. This could dramatically accelerate the development of high-performance software across many fields.
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Question & Answers

How does LLMLIFT's two-phase approach work in code transpilation?
LLMLIFT uses a two-phase process: program summary (PS) generation and invariant generation. In the first phase, the system generates a Python-based intermediate representation that summarizes the source program using DSL operators. The second phase creates logical assertions (invariants) to verify the equivalence between the summary and original code. This approach has been successfully tested on multiple DSLs, including Apache Spark and tensor processing languages, reducing development effort by 1000x in some cases. For example, when transpiling a Spark data processing routine, LLMLIFT would first create a Python summary of the operations, then generate invariants to ensure the transformed code produces identical results.
What are the main benefits of automated code transpilation for developers?
Automated code transpilation offers developers a seamless way to convert code between different programming languages without manual rewriting. The primary benefits include significant time savings, reduced risk of human error, and easier maintenance of code across multiple platforms. For instance, a developer can quickly port a web application from JavaScript to Python, or optimize code for specialized hardware without extensive manual translation. This technology is particularly valuable for organizations maintaining large codebases or developing cross-platform applications, as it ensures consistency and reduces development cycles while maintaining code quality.
How are AI language models transforming software development?
AI language models are revolutionizing software development by automating complex tasks and enhancing developer productivity. These models can assist with code generation, bug detection, documentation writing, and now even code translation between languages. They reduce the time and effort required for routine programming tasks, allowing developers to focus on more creative and strategic aspects of their work. For example, developers can use AI to quickly prototype applications, generate test cases, or convert legacy code to modern languages. This transformation is making software development more accessible and efficient across industries.

PromptLayer Features

  1. Testing & Evaluation
  2. LLMLIFT's verification process requires extensive testing of generated code translations and invariants, which aligns with PromptLayer's testing capabilities
Implementation Details
1. Create test suites for different DSL translations 2. Implement regression testing for generated Python code 3. Set up automated validation pipelines for syntax checking
Key Benefits
• Automated verification of code translations • Systematic tracking of translation accuracy • Early detection of LLM output errors
Potential Improvements
• Add specialized DSL-specific test templates • Implement parallel testing for multiple translations • Enhance error reporting granularity
Business Value
Efficiency Gains
Reduces manual verification effort by 80%
Cost Savings
Decreases testing resource requirements by automating validation
Quality Improvement
Ensures consistent code translation quality across different DSLs
  1. Workflow Management
  2. The two-phase approach of program summary generation and invariant generation maps directly to multi-step prompt orchestration
Implementation Details
1. Create separate prompt templates for PS and invariant generation 2. Build orchestration pipeline connecting both phases 3. Implement version tracking for generated code
Key Benefits
• Structured management of multi-step transpilation • Reproducible translation workflows • Version control for generated code
Potential Improvements
• Add intermediate validation steps • Implement rollback capabilities • Create DSL-specific workflow templates
Business Value
Efficiency Gains
Streamlines complex transpilation processes
Cost Savings
Reduces development time through reusable workflows
Quality Improvement
Ensures consistent translation process across projects

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