Cm

Intro

A compiler for a syntactically C-like imperative programming language, supporting (currently) array and struct. The front end is not very well-designed, while the mid end focuses on data flow analysis (with generic interface). The back end is trash (compiling to lua vm).

Programming Paradigm

Generic. This compiler has a generic interface to data flow problem using OCaml module system. The interface is designed to be extensible. All of my implementations of data flow analysis make use of this generic interface.
Visitor Pattern. In the intermediate representation and control flow graph, this compiler uses visitor pattern to traverse abstract syntax tree, graph, etc. This part makes use of OCaml object system. Using object to represent visitor makes it easy to record state while traversing.

Workflow

Lexing and Parsing
Sementic Checking (type checking, early liveness analysis)
Translating to IR
Optimizing (partial redundancy elimination, propagation + dead code elimination)
Translating to lua bytecode
(Auxilary) Producing .dot file for each procedure

Semantics Checking

The semant.ml file checks def-before-use, variable initialization (not include field initialization), type and proper return. For a sequence of statements, when checking proper return, if some statement already returns, the statements behind it can have arbitrary return semantics (since we really don't care about it).

Mimple

Mimple is an simplified version of Jimple (SOOT Java optimization framework). In this toy language, global vars are treated as static field reference.

Data Flow Analysis

The core data flow analysis engine is written in the dataflow.ml file. It uses a worklist algorithm. Currently supported domains: finite set domain (live variables, available expressions, etc.), finite map domain (constant propagation, copy propagation, etc.).

Partial redundancy elimination is done in a separate file pre.ml. It is the most challenging task in this project. This part is done according to the book "Compilers: Principles, Techniques, and Tools".

Requirement

This project requires

OCaml version >= 4.07.0
opam version >= 2.0.4
dune version >= 1.10.0
menhir

To install on MacOS, type

brew install ocaml
brew install opam
opam init
eval `opam env`
opam switch create 4.07.0
eval `opam env`
opam install dune
opam install menhir

To Install and Uninstall

make PLAT=macosx
make clean

Only macosx is supported:)

To Use

cd Cm
python run.py --file <path-to-file>

For example, to run the test program, type python run.py --file ./test/pre.cm, and the program will be executed. The binary file will be recorded into cm_out_bin.txt.

Possible Improvement

Make instruction data type more heavy-weight. Currently, the instruction data type contains pure instruction. For transformation purpose, we can augment it with reference to its predecessor and successor.

KomaEc / Cm

Cm