What is the SCC?

Simple C compiler (SCC) is a simple compiler of C language that is implemented by Python.

Quick Start

./driver.py <filename>

Currently, support the following flags.

• --lex: Run only the lexer pass.
• --parse: Run the lexer and parser passes.
• --codegen: Run the lexer, parser, and code generation passes.

Example:

./driver.py tests/resources/multi_digit.c   

Running this command will execute the driver logic to generate an assembly file for the input c file.

What is a compiler?

The compiler is a program that translates one language to another, in this case, converts source code written in C to Assembly.

From source code to executable file:

Loading

graph LR;
    source_code--Pre-processor-->preprocessed_source_code--Compiler-->assembly_code--Assembler-->object_file--Linker-->executable_file

Design

Compiler passes

The source code goes through 4 passes to be converted into an assembly file, shown as follows:

Loading

graph LR;
text.c--Lexer-->tokens--Parser-->abstract_syntax_tree--Assembly_Generation-->assembly--Code_Emitters-->program.s

Description:

• Lexer pass: breaks up the source code into a list of tokens.
• Parser pass: converts a list of tokens into AST -> easy to traverse and analyze.
• Assembly Generation pass: converts AST into assembly and organizes in a structure required by the compiler.
• Code Emission pass: writes those assembly structures to file.