8cc is a small C compiler. It supports a broad range of C99 features, such as compound literals or designated initializers. Some GNU extensions, such as computed gotos, are also supported. 8cc is self-hosting, which means 8cc can compile itself.

8cc's source code is carefully written to be as concise and easy-to-read as possible, so that the source code will eventually be a good study material to learn various techniques used in compilers. You might find the lexer, the preprocessor and the parser are already useful to learn how C source code is processed at each stage.

It does not produce optimized assembly code; 8cc treats the CPU as a stack machine. Local variables are always assigned on the stack. Operations in the form of A = B op C are executed in the following way.

1. Load B and C to registers
2. Apply op to yield a result
3. Write the results back to A's location

Producing optimized assembly is being planned.

Run make to build:

make

8cc comes with unit tests. To run the tests, give "test" as an argument:

make test

The following command compiles 8cc three times. The second generation binary and the third are self-compiled ones, and it's tested that they are identical. The unit tests are run for each generation of binaries.

make fulltest

8cc supports x86-64 Linux only. I'm using Ubuntu 11 as a development platform. It should work on other x86-64 Linux distributions.

Rui Ueyama rui314@gmail.com

• lcc: A Retargetable C Compiler: Design and Implementation https://www.amazon.com/dp/0805316701, https://github.com/drh/lcc

• TCC: Tiny C Compiler https://bellard.org/tcc/, https://repo.or.cz/w/tinycc.git/tree

• C99 standard final draft https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf

• C11 standard final draft https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf

• Dave Prosser's C Preprocessing Algorithm https://www.spinellis.gr/blog/20060626/

• x86-64 ABI https://www.x86-64.org/documentation/abi.pdf