⚙️ PCC — x86-64 C Compiler in Python

PCC is a fully-featured C compiler for the x86-64 architecture, written entirely in Python. Designed for clarity and modularity, it implements the complete C compilation pipeline — from source to assembly — without relying on parser generators like Yacc/Lex.

📘 Inspired by Writing a C Compiler by Nora Sandler, this project extends it significantly by implementing robust semantic analysis, IR generation, optimizations, struct and pointer support, and full code generation.

---

🚀 What’s Inside

Stage	Description
Lexing	Custom handwritten lexer with token stream generation
Parsing	Recursive-descent parser producing a complete AST
Semantic Analysis	Type checking, scope resolution, storage class, and promotions
IR Generation	Strongly-typed TACKY intermediate representation
Optimization	Constant folding, cast simplification, and dead store elimination
Codegen	Converts IR into real x86-64 assembly conforming to SysV ABI
Register Handling	Stack allocation + pseudo register resolution
Assembly Emission	GCC-compatible .s and .o files for final linking

---

✅ Supported C Features

• Primitive types: int, char, unsigned, long,double ,signed ,ulong
• Composite types: struct, array, pointer
• Type system: size/alignment handling, integer promotions, cast expressions
• Memory: stack variables, string literals, global/static storage
• Control flow: if, else, for, while,do while, ternary, return
• Expression evaluation: arithmetic, pointer math, logical ops
• Calling conventions: stack frame setup, argument passing (SysV ABI)
• Integration with gcc for preprocessing, assembling, and linking

---

🗂️ Project Structure

.
├── pcc.py             # Entry point — choose stage and compile
├── src/
│   ├── frontend/      # Lexer, parser, type checker, AST
│   └── backend/       # IR emission, optimizer, codegen
├── examples/          # Sample C test cases

---

💻 Usage

 pcc [stage] <input_file> [output_file] [libraries...]

Compilation Stages

Flag	Purpose
--lex	Token stream only
--parse	Parse and display AST
--validate	Run semantic analysis and scoping
--tacky	Emit TACKY IR
--codegen	Generate Assembly AST
-S	Emit .s file only (no link)
-c	Emit object file .o
run	Full compilation + linking
--help	View command options

---

✨ Example Commands

 pcc --lex examples/hello.c
 pcc --parse examples/loop.c
 pcc --tacky examples/math.c
 pcc run examples/structs.c

---

🧪 Sample Output

.globl main
.text
main:
  pushq %rbp
  movq %rsp, %rbp
  ...
  ret

🛡️ License & Credits

This project is an educational and non-commercial compiler implementation.

🔐 Intellectual Property & References

• This project draws foundational inspiration from Nora Sandler’s excellent guide:
  📘 Writing a C Compiler — https://github.com/nlsandler/nqcc2
  The original work is © Nora Sandler. All structural credits go to her for the roadmap and pedagogical flow.

• The System V x86-64 ABI documentation is referenced for architecture compliance.

• While many concepts are informed by existing compiler design materials, all parsing, semantic logic, intermediate representations, and code generation in this repository were implemented manually, without external compiler toolchains.

---

🔗 Repository

Source Code → github.com/rasheek16/pcc

---

👨‍💻 Author

Created by Rasheek — a systems programmer passionate about learning from the ground up. This compiler was written with a focus on low-level correctness, language design, and educational clarity.

---

📌 Final Note

This project was built to explore how C programs are translated into machine code — through lexing, parsing, semantic analysis, IR generation, and final assembly. Every stage is handcrafted to provide insight into how real-world compilers operate.

---