Optimizing Solidity Compiler

solx is a new optimizing compiler for EVM developed by Matter Labs.

Warning

The project is in alpha state and not suitable for production use.

solx passes our test suite, which includes:

• tests from the solc project
• real-life projects such as UniswapV2 and Mooniswap
• additional tests written by the solx team

Our pool of tests is updated with every solc release. Arbitrary contracts are expected to compile correctly, but some may be temporary affected by stack-too-deep errors. Benchmarks indicate that solx generates larger code than solc, but reduces the gas consumption on average.

Our mid-term goals:

• support EOF
• further reduce gas usage and bytecode size
• eliminate the need for inline assembly for efficiency
• emit ethdebug for optimized code
• run more tests of real-life projects in CI

Installation

You can download the existing pre-releases from the Releases GitHub page.

Usage

We recommend using solx via Foundry. It behaves in the same way as solc v0.8.30, so you can download the executable and specify:

[profile.solx]
solc_version = "/path/to/solx"

solx works with Hardhat as well, but requires some additional configuration.

Otherwise, the interface is mostly compatible with solc, so you can use it via CLI or standard JSON.

Demo

Check out this repository to see a demo of the current state of the compiler.

Architecture

solx consists of three main parts:

1. solx executable from this repository. The repository also contains parts of the compiler front end: Yul and EVM assembly translators.
2. era-solidity, an LLVM-friendly fork of the Solidity compiler, that emits Yul and EVM assembly for solx. Despite the repository name, it is not directly related to either ZKsync or ZKsync Era.
3. era-compiler-llvm, a fork of the LLVM project with an EVM target developed by the solx team.

The most important part of the project is the EVM target in LLVM. You can find its sources here.

Documentation

For the detailed usage guide, see the comprehensive documentation.

solx documentation is provided as an mdBook, and its sources available in the docs/ directory. To build the book, follow the instructions.

Alternatively, you may check out its Markdown representation in this repository.

See also:

• Solidity Documentation
• LLVM Documentation

Testing

To run the unit and CLI tests, execute cargo test at the repository root.

Troubleshooting

If you have multiple LLVM builds in your system, ensure that you choose the correct one to build the compiler. The environment variable LLVM_SYS_191_PREFIX sets the path to the directory with LLVM build artifacts, which typically ends with target-llvm/build-final. For example:

export LLVM_SYS_191_PREFIX="${HOME}/src/solx/target-llvm/build-final"

If you suspect that the compiler is not using the correct LLVM build, check by running set | grep LLVM, and reset all LLVM-related environment variables.

For reference, see llvm-sys and Local LLVM Configuration Guide.

License

• Crates solx and solx-solc are licensed under GNU General Public License v3.0
• Crates solx-standard-json, solx-evm-assembly, solx-yul are licensed under the terms of either
  • Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
  • MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
• era-solidity is licensed under GNU General Public License v3.0
• era-compiler-llvm is licensed under the terms of Apache License, Version 2.0 with LLVM Exceptions, (LICENSE or https://llvm.org/LICENSE.txt)

Contact Us

Email us at [email protected].