Compiler Explorer MCP

A Model Context Protocol (MCP) server that connects LLMs to the Compiler Explorer API, enabling them to compile code, explore compiler features, and analyze optimizations across different compilers and languages.

Example Questions

Here are some interesting questions you can ask your LLM using this MCP:

Compiler Feature Exploration

• "What is the earliest version of GCC that supports the #embed directive?"
• "Show me how different versions of Clang handle C++20 modules"
• "What optimization flags are available in Clang 12 that weren't in Clang 11?"
• "Can you demonstrate how MSVC and GCC handle C++20 coroutines differently?"

Optimization Analysis

• "What's the assembly difference between -O2 and -O3 for a simple recursive Fibonacci function in GCC 13?"
• "How does Clang's vectorization compare to GCC's for a basic matrix multiplication?"
• "Show me how different optimization levels affect tail-call optimization in this recursive function"
• "What's the impact of -ffast-math on this floating-point heavy computation?"

Language Feature Support

• "Which C++20 features are supported in the latest versions of GCC, Clang, and MSVC?"
• "Show me how different compilers implement std::optional's memory layout"
• "Compare how GCC and Clang handle C++20's constexpr virtual functions"
• "Demonstrate the differences in how Intel and GCC compilers auto-vectorize SIMD operations"

Assembly Deep Dives

• "What's the most efficient way to implement a population count in x86 assembly across different CPU architectures?"
• "Show me how different compilers optimize a simple string reverse function at -O3"
• "Compare the assembly output of a virtual function call vs a normal function call"
• "How do different compilers implement std::variant's type switching in assembly?"

Cross-Language Comparison

• "Compare the generated assembly for the same algorithm in C++, Rust, and Go"
• "How do exception handling mechanisms differ between C++ and Rust in terms of generated code?"
• "Show me the overhead of Rust's bounds checking compared to unchecked C++ array access"
• "Compare how C++ and D implement RAII in terms of generated assembly"

Performance Investigation

• "What's the assembly-level difference between using std::sort and a hand-written quicksort?"
• "Show me how different string concatenation methods compare in terms of generated instructions"
• "Compare the efficiency of std::map vs std::unordered_map operations in assembly"
• "How do different smart pointer implementations affect inlining and code size?"

Usage

1. Install the required dependencies:

uv add fastapi httpx mcp[cli] pydantic python-dotenv uvicorn websockets

2. Run the MCP server:

fastmcp install server.py

3. Connect your LLM client to the MCP server and start exploring compiler internals!