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CSC

CSC is a simple and easy extensible C Subset Compiler. It's not realy for production, it was made JUST FOR FUN. It contains lexer, parser, llvm-ir-codegenerator and SSA-form-builder.

Tech

CSC uses a number of open source projects to work properly:

• LLVM - Framework for building compilers and codegenerators.

And of course CSC itself is open source with a public repository on GitHub.

Installation

CSC requires LLVM v5.0+ to run.

Install the dependencies and build compiler.

$ sudo apt-get install llvm
$ sudo apt-get install clang
$ git clone https://github.com/masyagin1998/CSC.git
$ cd CSC
$ make all  # to make compiler
$ make test # to check compiler's work

What can it do?

CSC supports simplified version of C89 with:

• int variables definitions;
• while loops;
• if-then and if-then-else statements;
• inner if and while statements (multiple inner statements)
• all arithmetical and logical operations;
• and many other;

Lexer

Linear Object-Oriented lexer with error recovery and comments ignoring.

Parser

Recursive top-down parser (I know it is shitty, but OK for small projects) for simplified to LL(1) C grammar, which turns lexemas to Abstract Syntax Tree (AST). AST can be debugged to file using in human-readable format.

Codegenerator

Codegenerator to LLVM IR BitCode from abstract syntax tree. Yon can link generated object files (*.o files) with main.c

SSA-builder

Classical code-generation algorithm, which firstly creates Control Flow Graph (CFG) from AST, and then creates SSA-form using Dominance Frontier Algorithm (DFA).

Examples

• Check if number is even

  Code	SSA

• Get sign of number

  Code	SSA

• Fibonacci

  Code	SSA

Many thanks to:

Anatoly Sinyavin - BMSTU Optimal Code Generation teacher