The xcc700 is a very small, lightweight C compiler designed specifically for the ESP32 microcontroller. It is like a mini version of GCC or clang, but this system has some limitations. Instead of generating Windows .exe files, it produces ELF binaries for the Xtensa CPU, which is the processor architecture used in ESP32. Because it is so small, the compiler itself can run on the ESP32 and compile C code on the device itself, which is something you normally don’t see; most compilers are far too large to fit on microcontrollers. the biggest strength of this system is that the entire compiler is implemented in roughly 700 lines of C code, so it is easy to read, understand and also modify.
This supports the useful Subsets of the C language, things like int, char, pointer, arrays, while loops, if/else, arithmetic operations, and function calls. However, it cant able to compile the advanced features like for loops, struct, union, floating point operations and full standard libraries. Because of this, it's not able to replace full compilers like GCC, but rather helps to understand how a compiler actually works.
Even though it has some limitations, it is very useful for education and experimentation. You can compile xcc700 on a normal PC and use it as a small cross-compiler, or even embed it into ESP32 firmware to compile and run code at runtime using tools like ESP-IDF’s elf_loader.
