Stories with Tag Cross-Compilation

• Rust to C compiler – 95.9% test pass rate, odd platforms

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  Posted: 2025-04-12 04:21:15

  Verbose tl;dr

  The cg_clif project has made significant progress in compiling Rust to C, achieving a 95.9% pass rate on the Rust test suite. This compiler leverages Cranelift as a backend and utilizes a custom ABI for passing Rust data structures. Notably, it's now functional on more unusual platforms like wasm32-wasi and thumbv6m-none-eabi (for embedded ARM devices). While performance isn't a primary focus currently, basic functionality and compatibility are progressing rapidly, demonstrating the potential for compiling Rust to a portable C representation.

  This blog post by Fractal Fir details the ongoing development of cg_clif (now clif-util), a tool designed to compile Rust code into C code. The author focuses on recent progress and challenges encountered while targeting "odd platforms"—specifically, WebAssembly (Wasm) and embedded systems like the AVR microcontroller family.

  A significant milestone is reaching a 95.9% pass rate on the Rust compiler's extensive test suite when compiling to C and subsequently to Wasm. This achievement highlights the project's increasing maturity and ability to handle complex Rust constructs even when targeting non-traditional environments. The author attributes this success partly to the use of Cranelift, a code generation library that facilitates targeting diverse architectures.

  However, the journey isn't without hurdles. The post explains that supporting inline assembly, a feature frequently used for low-level optimization and hardware interaction, presents significant difficulties. The disparity between the assembly syntax understood by the Rust compiler's LLVM backend and the syntax expected by the Wasm target requires intricate translation, a problem not yet fully solved. The author acknowledges this as a major area of ongoing work.

  Furthermore, the post discusses the challenges in targeting the AVR microcontroller architecture. AVR, a popular choice for resource-constrained embedded systems, poses unique constraints due to its limited instruction set and memory capacity. The author describes working on implementing calling conventions compatible with AVR and tackling the intricacies of handling data types and memory management specific to this platform. While significant progress has been made, targeting AVR remains a work in progress, with complete support still on the horizon.

  The overarching goal of cg_clif is to expand the reach of Rust code by enabling compilation to C, thereby unlocking the ability to target platforms not directly supported by the standard Rust compiler. The project leverages the Cranelift code generation library and the clif intermediate representation to achieve this cross-compilation. While challenges remain, particularly regarding inline assembly and support for resource-constrained environments like AVR, the project demonstrates promising progress towards enabling broader platform compatibility for Rust code. The author expresses optimism about future developments and invites contributions from the community.

  • Rust
  • C
  • compiler
  • Cross-Compilation
  • Code Generation
  • mrustc
  • Fractal Fir
  • testing
  • performance
  • WebAssembly
  • Game Boy Advance
  • Uncommon Architectures
  • Portable Code

  Summary of Comments ( 164 )
  https://news.ycombinator.com/item?id=43661329

  Verbose tl;dr

  Hacker News users discussed the impressive 95.9% test pass rate of the Rust-to-C compiler, particularly its ability to target unusual platforms like the Sega Saturn and Sony PlayStation. Some expressed skepticism about the practical applications, questioning the performance implications and debugging challenges of such a complex transpilation process. Others highlighted the potential benefits for code reuse and portability, enabling Rust code to run on legacy or resource-constrained systems. The project's novelty and ambition were generally praised, with several commenters expressing interest in the developer's approach and future developments. Some also debated the suitability of "compiler" versus "transpiler" to describe the project. There was also discussion around specific technical aspects, like memory management and the handling of Rust's borrow checker within the C output.

  The Hacker News post titled "Rust to C compiler – 95.9% test pass rate, odd platforms" sparked a discussion with several interesting comments. Many commenters focused on the complexities and nuances of compiling Rust to C, particularly given Rust's unique memory management features.

  One commenter highlighted the challenges inherent in translating Rust's borrow checker and ownership model into C, which lacks these built-in mechanisms. They questioned how the compiler handled these crucial aspects of Rust, expressing skepticism about achieving true compatibility without significant runtime overhead or limitations. This comment resonated with others who also expressed concern about the potential performance implications and the difficulty of replicating Rust's safety guarantees in C.

  Another commenter pointed out the inherent difficulty in targeting "odd platforms," as mentioned in the title. They elaborated on the potential issues with varying C standard library implementations and the complexities of ensuring compatibility across diverse architectures and operating systems. This prompted a discussion about the trade-offs between portability and performance when attempting such a compilation process.

  Several comments also touched on the potential use cases of such a compiler. Some suggested it could be valuable for embedded systems or environments where Rust isn't directly supported. Others questioned the practicality, arguing that if the target platform supports a C compiler, it might also be feasible to support a Rust compiler directly, potentially negating the need for a transpilation step.

  The discussion also explored alternative approaches, such as compiling Rust to LLVM bitcode and then using LLVM to generate C code. This was presented as a potentially more robust approach that could leverage LLVM's optimizations and platform support.

  Finally, some comments expressed interest in the specific platforms targeted by the project and requested more details about the remaining 4.1% of failing tests. They were curious about the nature of these failures and whether they represented fundamental limitations or solvable issues. Overall, the comments reflected a mixture of curiosity, skepticism, and cautious optimism about the potential of a Rust-to-C compiler.

• Using the Rust standard library with the NuttX RTOS

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  Posted: 2025-01-27 18:16:23

  Verbose tl;dr

  This blog post details how to leverage the Rust standard library (std) within applications running on the NuttX Real-Time Operating System (RTOS), a common choice for embedded systems. The author demonstrates a method to link the Rust std components, specifically write() for console output, with NuttX's system calls. This allows developers to write Rust code that feels idiomatic, using familiar functions like println!(), while still targeting the resource-constrained environment of NuttX. The process involves creating a custom target specification JSON file and implementing shim functions that bridge the gap between the Rust standard library's expectations and the underlying NuttX syscalls. The result is a simplified development experience, enabling more portable and maintainable Rust code on embedded platforms.

  This blog post explores the integration of the Rust programming language with the NuttX Real-Time Operating System (RTOS), specifically focusing on leveraging the Rust standard library (std) within the NuttX environment. The author's primary motivation stems from the desire to utilize familiar and powerful Rust std features, like formatted printing with println!, within embedded systems constrained by limited resources. They argue that while the no_std approach, which excludes the standard library, is common in embedded Rust development, it sacrifices valuable functionalities and introduces complexities when dealing with tasks like string formatting and error handling.

  The post details the process of configuring a NuttX build system to accommodate Rust std. This involves configuring NuttX's C library to provide the necessary system calls expected by the Rust standard library. The author elucidates the critical role of the libstd crate, a part of the Rust standard library that interacts directly with the underlying operating system, and how its dependencies on system calls must be satisfied by the RTOS.

  A key aspect of the integration process is the careful mapping of Rust's system call abstractions to the equivalent functionalities provided by NuttX. The blog post meticulously describes how specific system calls, such as write, read, exit, and memory allocation functions, are implemented within the NuttX context and linked to the Rust standard library. This mapping requires adapting NuttX's C-style functions to match the signatures expected by Rust, ensuring seamless interoperability.

  The author provides practical examples demonstrating the successful integration, showcasing the use of println! for formatted output to the NuttX console. They also highlight the advantages of this approach, emphasizing the reduced development time and improved code readability achieved by leveraging the familiar Rust std APIs. Furthermore, the post discusses the implications for error handling, explaining how the Rust std error management mechanisms can be integrated with NuttX. Finally, the author discusses the memory management considerations, particularly concerning the heap and stack allocation within the NuttX environment when using the Rust standard library. They address how to configure NuttX to provide the heap memory expected by std, making dynamic memory allocation possible in Rust programs running on NuttX.

  • Rust
  • NuttX
  • RTOS
  • Embedded Systems
  • Embedded Rust
  • Standard Library
  • Real-Time Operating System
  • programming
  • Software Development
  • Operating Systems
  • Cross-Compilation
  • Microcontrollers
  • Arm

  Summary of Comments ( 14 )
  https://news.ycombinator.com/item?id=42843989

  Verbose tl;dr

  Hacker News users discuss the challenges and advantages of using Rust with NuttX. Some express skepticism about the real-world practicality and performance benefits, particularly regarding memory usage and the overhead of Rust's safety features in embedded systems. Others highlight the potential for improved reliability and security that Rust offers, contrasting it with the inherent risks of C in such environments. The complexities of integrating Rust's memory management with NuttX's existing mechanisms are also debated, along with the potential need for careful optimization and configuration to realize Rust's benefits in resource-constrained systems. Several commenters point out that while intriguing, the project is still experimental and requires more maturation before becoming a viable option for production-level embedded development. Finally, the difficulty of porting existing NuttX drivers to Rust and the lack of a robust Rust ecosystem for embedded development are identified as potential roadblocks.

  The Hacker News post "Using the Rust standard library with the NuttX RTOS" (linking to an article explaining how to run Rust's standard library on the NuttX real-time operating system) generated a modest amount of discussion, focusing primarily on the complexities and trade-offs involved in such an integration.

  One commenter questioned the practical benefits of using the Rust standard library in an embedded RTOS environment, given its potential impact on resource usage. They wondered if using the no_std approach in Rust wouldn't be more suitable for such constrained systems, as it provides greater control over memory management and resource allocation. This prompted a response explaining that the standard library can offer valuable abstractions and functionalities, such as collections and formatted I/O, that can simplify development even in embedded contexts. They pointed out that the choice between std and no_std depends on the specific project requirements and resource constraints. The benefit of using std is that you can have better testability and reuse more existing code for functionality rather than reimplementing everything for a no-std environment.

  Another commenter highlighted the challenges associated with using dynamic memory allocation in real-time systems, especially in safety-critical applications. They noted that the predictability required by RTOS often conflicts with the dynamic nature of memory allocation, potentially leading to unpredictable delays and instability. This is a general consideration for embedded development and isn't specific to Rust.

  There was discussion around the nature of the alloc crate in Rust, which provides the underlying mechanisms for dynamic memory allocation within the standard library. A commenter explained how this crate allows for customization of the memory allocator, enabling developers to tailor it to the specific needs of their embedded system. This flexibility allows the Rust standard library to be used even on systems with unconventional memory management schemes. This suggests a potential solution to the dynamic memory allocation concerns raised earlier, allowing for greater control and predictability in an RTOS environment.

  Finally, one comment mentioned the use of Rust in spacecraft, specifically referencing a project that utilized the language for a time-of-flight mass spectrometer on a Mars mission. While not directly related to the original article's topic, this comment showcases a real-world example of Rust being employed in a highly constrained and critical embedded environment, lending further credence to the idea that Rust can be a viable option for such systems.