Key Facts
- ✓ The compiler is written in 700 lines of code
- ✓ It generates REL ELF binaries runnable via ESP-IDF elf_loader
- ✓ Treats the Xtensa CPU as a stack machine (no register allocation)
- ✓ Compilable on Mac and Linux for cross-compiling to ESP32
- ✓ Builds in 40 ms at 17,500 lines/sec
Quick Summary
A developer has released xcc700, a new self-hosting mini C compiler designed specifically for the ESP32 platform. The entire compiler is written in just 700 lines of code, making it an exceptionally compact tool for embedded development.
Despite its small size, the compiler supports essential features required for self-hosting. It operates as a single-pass, recursive descent compiler that directly emits relocatable ELF binaries. These binaries are fully runnable using the standard ESP-IDF elf_loader.
The project was created for fun and a specific cyberdeck project. It is currently compilable on Mac and likely Linux, enabling developers to cross-compile for the ESP32 on these systems.
Technical Architecture and Design
The xcc700 compiler utilizes a single-pass, recursive descent architecture with direct emission. This approach allows for efficient processing of code without the overhead of multiple parsing stages. The compiler generates REL ELF binaries, which are compatible with the ESP-IDF elf_loader environment.
To maintain its minimal footprint, the compiler treats the Xtensa CPU as a stack machine for simplicity. This design choice means it does not implement complex register allocation or window usage, streamlining the compilation process.
The tool is described as having "very basic features only, just enough for self-hosting." This philosophy ensures that the compiler remains lightweight while still capable of compiling its own source code.
"My best hope is that some fork might grow into a unique nice language tailored to the esp32 platform. I think it is underrated in userland hobby projects."
— Project Author
Platform Compatibility and Usage
xcc700 was developed with versatility in mind regarding host operating systems. It is explicitly stated to be compilable on Mac, with the expectation that it will also work on Linux. This cross-platform capability extends to its target architecture, allowing developers to cross-compile specifically for the ESP32 from their desktop machines.
The project originated from a desire to create a unique tool for a cyberdeck project. The author expressed hope that the compiler might eventually be forked and grow into a unique language tailored specifically to the ESP32 platform, which they believe is underrated in userland hobby projects.
Performance Metrics
Performance data released with the compiler shows impressive efficiency for such a small codebase. In a sample output from an ESP32 device, the compiler processed 700 lines of input containing 7,977 tokens.
The compilation generated specific binary statistics:
- 69 Functions and 91 Globals defined
- 152 Literals and 1,027 Patches in the relocatable section
- Memory usage included 1041 B .rodata and 17120 B .bss
- Output binary size was 27735 B .text resulting in a 33300 B ELF file
Most notably, the entire build process completed in 40 ms, achieving a throughput of 17,500 lines/sec.
