This is a toy project of mine, with the goal of making a compiler for C, written in C, which is able to compile itself. The motivation is simply to learn more about compiler construction and C-programming. Beyond that, there is no purpose.

Most language constructs in C89 are supported, in addition to some elements from later standards. Notable omissions include bit fields, and anything having to do with floating point numbers. Not all features used in glibc headers are supported, so the Makefile assumes you have musl installed. This is still work in progress, but as of now it is finally self-hosting.

Implementation is entirelly C89, using only the standard headers and some POSIX extensions. There are no external dependencies.

The current version can produce x86_64 assembly, output in GNU as syntax. The GNU assembler and linker can be used to create actual object files.

Here is compiling "hello world" from terminal, typing in interactive mode:

$ bin/lacc -S -o hello.s
int puts(const char *s);

int main(void) {
	puts("Hello World!");
	return 0;
}

$ cat hello.s
	.data
	.align	16
__func__.1:
	.string	"main"
	.text
	.globl	main
	.type	main, @function
main:
	pushq	%rbp
	movq	%rsp, %rbp
	subq	$4, %rsp
.L1:
	movq	$.LC0, %rdi
	call	puts
	movl	%eax, -4(%rbp)	# store .t0
	movl	$0, %eax
	leaveq
	retq
	.size	main, .-main
	.section .rodata
.LC0:
	.string "Hello World!"

$ gcc hello.s -o hello && ./hello
Hello World!

There is also an option to produce DOT diagrams of the internal CFG representation:

int main(int argc, char *argv[]) {
	int i, sum = 0;
	for (i = 0; i < argc; ++i) {
		sum += i;
	}
	return sum;
}