Contributing to rustc_codegen_gcc

Welcome to the rustc_codegen_gcc project! This guide will help you get started as a contributor. The project aims to provide a GCC codegen backend for rustc, allowing Rust compilation on platforms unsupported by LLVM and potentially improving runtime performance through GCC's optimizations.

Getting Started

Setting Up Your Development Environment

For detailed setup instructions including dependencies, build steps, and initial testing, please refer to our README. The README contains the most up-to-date information on:

Required dependencies and system packages
Repository setup and configuration
Build process
Basic test verification

Once you've completed the setup process outlined in the README, you can proceed with the contributor-specific information below.

Communication Channels

Matrix: Join our Matrix channel
IRC: Join us on IRC
GitHub Issues: For bug reports and feature discussions

We encourage new contributors to join our communication channels and introduce themselves. Feel free to ask questions about where to start or discuss potential contributions.

Understanding Core Concepts

Common Development Tasks

Running Specific Tests

To run specific tests, use appropriate flags such as:

./y.sh test --test-libcore
./y.sh test --std-tests
./y.sh test --cargo-tests -- <name of test>

Additionally, you can run the tests of libgccjit:

# libgccjit tests
cd gcc-build/gcc
make check-jit
# For a specific test:
make check-jit RUNTESTFLAGS="-v -v -v jit.exp=jit.dg/test-asm.cc"

Debugging Tools

The project provides several environment variables for debugging:

CG_GCCJIT_DUMP_GIMPLE: Dumps the GIMPLE IR
CG_RUSTFLAGS: Additional Rust flags
CG_GCCJIT_DUMP_MODULE: Dumps a specific module
CG_GCCJIT_DUMP_TO_FILE: Creates C-like representation

Full list of debugging options can be found in the README.

Making Contributions

Finding Issues to Work On

Look for issues labeled with good first issue or help wanted
Check the progress report for larger initiatives
Consider improving documentation or investigating failing tests (except failing-ui-tests12.txt)

Pull Request Process

Fork the repository and create a new branch
Make your changes with clear commit messages
Add tests for new functionality
Update documentation as needed
Submit a PR with a description of your changes

Code Style Guidelines

Follow Rust standard coding conventions
Ensure your code passes rustfmt and clippy
Add comments explaining complex logic, especially in GCC interface code

Additional Resources

Rustc Dev Guide
GCC Internals Documentation
Project-specific documentation in the doc/ directory:

Getting Help

If you're stuck or unsure about anything:

Check the existing documentation in the doc/ directory
Ask in the IRC or Matrix channels
Open a GitHub issue for technical problems
Comment on the issue you're working on if you need guidance

Remember that all contributions, including documentation improvements, bug reports, and feature requests, are valuable to the project.

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