Writing C Compiler

I am now writing c compiler to learn how a compiler works.

C Compiler translates source code(strings) into assembly language.

First of all, this Compiler breaks strings into tokens, and then parses strings into nodes using tokens, and finally generates assembly.

Tokenizer
Parser
Code Generator

Tokenizer

Tokenizer traverses strings and creates a linkedlist of tokens.

Parser

Parser parses strings into nodes.

To implement parser, we need compiler design. Normally we use BNF(Backus-Naur Form) notation to design compiler.

BNF notation is like

expr = num ("+" num | "-" num)*

This is a plain example for addtion and subtraction. This expression takes a number, and add or subtract another number if it is provided(* means 0 or more).

Code Generator

Code generator generates assembly.

The preivous BNF example is translated to assembly like

.intel_syntax noprefix
.globl main
main:
    push 2
    push 3
    pop rdi
    pop rax
    add rax, rdi
    push rax
    pop rax
    ret

It means 2 + 3, which is implemented as stack machine.

It pushes 2 numbers, 2, 3, assigns 3 to rdi(a assembly register), 2 to rax(a assembly register). At last it calculates 2 + 3 and assigns result to rax. In this example the next 2 statements can be ignored, since it just does rax = rax. ret returns result, which is 5.

Progress

I implemented math calculation so far.

My source code is uploaded on github.

Tokenizer#

Parser#

Code Generator#

Progress#

Tokenizer

Parser

Code Generator

Progress