Overview

This project implements a MIPS code generator for ALGOL-like language constructs using an Abstract Syntax Tree (AST). The compiler is developed in stages to gradually build up complexity and provide a strong learning foundation in compiler construction and code generation.

The core of the project is housed in the lab9 folder, which contains the complete compiler pipeline—from lexical analysis and parsing (using LEX and YACC) to AST construction and MIPS code emission.

Purpose

The main goal is to generate MIPS assembly code for ALGOL constructs while reinforcing compiler design principles and gaining hands-on experience with:

Abstract Syntax Trees (ASTs)

Activation records

Code emission for control flow (jumps, labels, directives)

MIPS header setup and data definitions (scalars, arrays, strings)

Input/output handling and expression evaluation

Features

Command-line interface to specify output files

Support for basic ALGOL constructs including:

    Variable declarations

    Arithmetic expressions

    Assignments

    Conditional statements (if)

    Loops (while)

    Arrays (simplified handling)

AST traversal for code emission (emit.c)

Modular structure encouraging documentation and clear function-level understanding

Usage

Compilation

cd lab9

make

Running the Compiler

To compile an .al ALGOL source file and generate MIPS assembly:

./lab9 -o [output file name] < program.al

Running the Generated MIPS Code

To run the resulting MIPS assembly using the MARS simulator:

java -jar Mars4_5.jar sm output.asm

Note: Ensure Mars4_5.jar is in your working directory or provide the correct path, but is included anyways into lab9 directory

Project Structure

lab9.l – Lexical analyzer

lab9.y – YACC grammar for ALGOL

ast.c/h – Abstract Syntax Tree construction

emit.c – MIPS code generation

main.c – Main driver with command-line handling

lab9/ – Folder containing the complete compiler

Learning Objectives

Understand and implement a multi-stage compiler pipeline

Translate high-level constructs into low-level MIPS code

Practice structured compiler design and modular development

Gain familiarity with activation records and memory layout in MIPS