Enable Link-Time Optimization (LTO) For WhatsApp's Rust Project

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Introduction

As a developer, optimizing the performance of your code is crucial for delivering a seamless user experience. In this article, we will explore the benefits of enabling Link-Time Optimization (LTO) for WhatsApp's Rust project. We will also discuss the potential improvements that can be achieved by applying Profile-Guided Optimization (PGO) and Post-Link Optimization (PLO).

What is Link-Time Optimization (LTO)?

Link-Time Optimization (LTO) is a compilation technique that optimizes the code after it has been linked. This process involves analyzing the entire program, including all the object files, and making optimizations that would not be possible during the compilation phase. LTO can lead to significant improvements in code size and performance.

Benefits of LTO

Enabling LTO for WhatsApp's Rust project can bring several benefits, including:

  • Reduced binary size: By optimizing the code after it has been linked, LTO can reduce the size of the binary, making it easier to distribute and deploy.
  • Improved performance: LTO can lead to significant improvements in code performance, making it more responsive and efficient.
  • Enhanced security: By reducing the size of the binary, LTO can also improve the security of the code by reducing the attack surface.

Enabling LTO for WhatsApp's Rust Project

To enable LTO for WhatsApp's Rust project, you can follow these steps:

  1. Update the Cargo.toml file: Add the following line to the [profile.release] section of the Cargo.toml file:
lto = true
  1. Enable FatLTO: Add the following line to the [profile.release] section of the Cargo.toml file:
lto = "fat"
  1. Set codegen-units to 1: Add the following line to the [profile.release] section of the Cargo.toml file:
codegen-units = 1
  1. Run cargo build --release: Run the cargo build --release command to build the project with LTO enabled.

Results

After enabling LTO for WhatsApp's Rust project, we observed the following results:

  • erlang-language-platform:
    • ThinLTO (current default for the Release profile): 174 Mib, clean build time: 58s
    • FatLTO + codegen-units = 1: 144 Mib, clean build time: 2m 47s
  • crashdump_viewer_cli:
    • Release: 6 Mib, clean build time: 16s
    • Release + codegen-units = 1 + Fat LTO: 4.2 Mib, clean build time: 34s
  • erlfuzz:
    • Release: 3.9 Mib, clean build time: 7s
    • Release + codegen-units = 1 + Fat LTO: 2.9 Mib, clean build time: 19s

Additional Improvements

In addition to enabling LTO, we can also explore other optimization techniques, such as:

  • -Guided Optimization (PGO): PGO involves collecting profile data on the code's execution and using that data to optimize the code. This can lead to significant improvements in code performance.
  • Post-Link Optimization (PLO): PLO involves optimizing the code after it has been linked, similar to LTO. However, PLO can lead to more aggressive optimizations, which can result in larger binaries.

Conclusion

Enabling LTO for WhatsApp's Rust project can bring significant benefits, including reduced binary size and improved performance. By following the steps outlined in this article, you can enable LTO for your project and take advantage of these benefits. Additionally, exploring other optimization techniques, such as PGO and PLO, can lead to even more significant improvements in code performance.

Future Work

In the future, we can explore other optimization techniques, such as:

  • Code splitting: Code splitting involves splitting the code into smaller modules, which can make it easier to optimize and deploy.
  • Tree shaking: Tree shaking involves removing unused code from the binary, which can reduce its size and improve performance.

Introduction

In our previous article, we explored the benefits of enabling Link-Time Optimization (LTO) for WhatsApp's Rust project. We discussed the potential improvements that can be achieved by applying LTO, as well as other optimization techniques, such as Profile-Guided Optimization (PGO) and Post-Link Optimization (PLO). In this article, we will answer some frequently asked questions (FAQs) about enabling LTO for WhatsApp's Rust project.

Q: What is Link-Time Optimization (LTO)?

A: Link-Time Optimization (LTO) is a compilation technique that optimizes the code after it has been linked. This process involves analyzing the entire program, including all the object files, and making optimizations that would not be possible during the compilation phase.

Q: What are the benefits of enabling LTO for WhatsApp's Rust project?

A: Enabling LTO for WhatsApp's Rust project can bring several benefits, including:

  • Reduced binary size: By optimizing the code after it has been linked, LTO can reduce the size of the binary, making it easier to distribute and deploy.
  • Improved performance: LTO can lead to significant improvements in code performance, making it more responsive and efficient.
  • Enhanced security: By reducing the size of the binary, LTO can also improve the security of the code by reducing the attack surface.

Q: How do I enable LTO for WhatsApp's Rust project?

A: To enable LTO for WhatsApp's Rust project, you can follow these steps:

  1. Update the Cargo.toml file: Add the following line to the [profile.release] section of the Cargo.toml file:
lto = true
  1. Enable FatLTO: Add the following line to the [profile.release] section of the Cargo.toml file:
lto = "fat"
  1. Set codegen-units to 1: Add the following line to the [profile.release] section of the Cargo.toml file:
codegen-units = 1
  1. Run cargo build --release: Run the cargo build --release command to build the project with LTO enabled.

Q: What are the potential drawbacks of enabling LTO for WhatsApp's Rust project?

A: While enabling LTO for WhatsApp's Rust project can bring several benefits, there are also some potential drawbacks to consider:

  • Increased build time: Enabling LTO can increase the build time of the project, as the compiler needs to analyze the entire program and make optimizations.
  • Larger binaries: While LTO can reduce the size of the binary in some cases, it can also lead to larger binaries in other cases, especially if the code is not optimized properly.

Q: Can I use LTO with other optimization techniques, such as PGO and PLO?

A: Yes, you can use LTO with other optimization techniques, such as PGO and PLO. In fact, using LTO in combination with other optimization techniques can lead to even more significant improvements in code performance.

Q: How do I know if LTO is working for my project?

A: To determine if LTO is working for your project, you can use various tools and techniques, such as:

  • Binary size analysis: Use tools like size or du to analyze the size of the binary before and after enabling LTO.
  • Performance benchmarking: Use tools like criterion or bench to benchmark the performance of the code before and after enabling LTO.
  • Code analysis: Use tools like clang or gcc to analyze the code and determine if LTO is making any optimizations.

Conclusion

Enabling LTO for WhatsApp's Rust project can bring significant benefits, including reduced binary size and improved performance. By following the steps outlined in this article, you can enable LTO for your project and take advantage of these benefits. Additionally, exploring other optimization techniques, such as PGO and PLO, can lead to even more significant improvements in code performance.