[![Test](https://github.com/PhilippRados/wrecc/actions/workflows/test.yml/badge.svg)](https://github.com/PhilippRados/wrecc/actions/workflows/test.yml) ![](https://img.shields.io/github/license/PhilippRados/wrecc) ![](https://img.shields.io/badge/made_for-UNIX-lightgrey) ![](https://img.shields.io/badge/Architecture-x86--64-blue) `wrecc` is a small,lean x86-64 C99 compiler written from scratch. The name is a play on the word _wreck_ which describes a rusting ship on the sea floor. The compiler emits [x86-64](https://en.wikipedia.org/wiki/X86-64) assembly in [AT&T syntax](https://staffwww.fullcoll.edu/aclifton/courses/cs241/syntax.html), it adheres to the [System V ABI](https://wiki.osdev.org/System_V_ABI) which I could only test for Ubuntu and Macos. There are no dependencies you only need your assembler and linker which the compiler then invokes to create the final binary. ### Table of contents * [Installation](#installation) + [Pre-built binaries](#binaries) + [Cargo](#cargo) * [Features](#features) + [Preprocessor](#preprocessor) + [Compiler](#compiler) + [Supported keywords](#keywords) + [Unimplemented features](#unimplemented) + [Error messages](#errors) + [Ast pretty-printer](#ast) * [Testing](#testing) + [Unit-tests](#unit) + [Snapshot-tests](#snap) + [Fuzzer](#fuzzer) * [Troubleshooting](#troubleshooting) * [Contribution](#contribution) * [Project goals](#goals) * [Resources](#resources) ## Installation ### Pre-built binaries If you don't have the rust toolchain installed on your system you can install the latest binary (MacOs, Linux) from the releases directly: ``` curl --proto '=https' --tlsv1.2 -LsSf https://github.com/PhilippRados/wrecc/releases/download/v0.2.0/wrecc-installer.sh | sh ``` ### Cargo Using `cargo binstall` ``` cargo binstall wrecc ``` or building from source ``` cargo install wrecc ``` ## Features Since not all keywords are currently implemented wrecc uses [custom standard-headers](https://github.com/PhilippRados/wrecc/tree/master/include) which are built directly into the binary ### Preprocessor The preprocessor implements all [C99 preprocessor directives](https://en.cppreference.com/w/c/keyword), except `#line`, `#error` and `#pragma`. Most prominently it currently also misses function-like macros which are on the agenda though. ### Compiler #### Supported Keywords

#### Other than that it even supports:

Aggregate initialization with designated initializers

```C struct { union { int foo; long baz; } nested; int array[16]; } bar = { .nested.foo = 3, .array[6] = 1}; ```

Function pointers

```C #include typedef int (*BinaryOperation)(int, int); typedef struct { BinaryOperation add; BinaryOperation subtract; } Calculator; int add(int a, int b) { return a + b; } int subtract(int a, int b) { return a - b; } int main() { Calculator calc = {add, subtract}; printf("Result of addition: %d\n", calc.add(10, 5)); printf("Result of subtraction: %d\n", calc.subtract(10, 5)); } ```

Constant folding

```C char **string_offset = (char **)&"hello" + (int)(3 * 1); int array[(long)3 * 2 - 1]; ```

#### Unimplemented Features Aside from the missing keywords these are the main missing features: - [x] Arrays with unspecified size - [x] Compiling multiple files at once - [ ] Raw structs/unions as function argument-/return-types - [ ] Floating point types
Here is a list of all the stuff still missing: [todo](https://placid-eris-c19.notion.site/check-all-errors-from-c-testsuite-6f3fa2a3c24a4711b5e89f45354db540?pvs=4) ### Error messages Wrecc also has nice looking messages. Error reporting doesn't stop after the first error. Using the `--no-color` option you can switch off color-highlighting in errors. Currently there are only errors and no warnings.

C code	Errors
```C int foo(void); int main() { int a = foo(1); long p = a; return p 2; } ```

### Ast pretty-printer When compiling using the `--dump-ast` option it prints the parse-tree

C code	AST
```C #define SIZE 16 void foo(char); int main() { int arr[SIZE] = {1, 2}; char p = (char)(*arr + 3); switch (p) { case 'c': foo(p); } } ```	``` Declaration: -Decl: 'foo' FuncDef: 'main' -Declaration: --Init: 'arr' ---Aggregate: ----Scalar: -----Literal: 1 ----Scalar: -----Literal: 2 -Declaration: --Init: 'p' ---Scalar: ----Cast: 'char' -----Grouping: ------Binary: '+' -------Unary: '*' --------Ident: 'arr' -------Literal: 3 -Switch: --Ident: 'p' --Block: ---Case: ----Literal: 99 ----Expr: -----FuncCall: ------Ident: 'foo' ------Ident: 'p' ```

C code

AST

```C #define SIZE 16 void foo(char); int main() { int arr[SIZE] = {1, 2}; char p = (char)(*arr + 3); switch (p) { case 'c': foo(p); } } ```

``` Declaration: -Decl: 'foo' FuncDef: 'main' -Declaration: --Init: 'arr' ---Aggregate: ----Scalar: -----Literal: 1 ----Scalar: -----Literal: 2 -Declaration: --Init: 'p' ---Scalar: ----Cast: 'char' -----Grouping: ------Binary: '+' -------Unary: '*' --------Ident: 'arr' -------Literal: 3 -Switch: --Ident: 'p' --Block: ---Case: ----Literal: 99 ----Expr: -----FuncCall: ------Ident: 'foo' ------Ident: 'p' ```

#### Inspect all options by running `wrecc --help` ## Testing #### Unit tests ``` cargo test --workspace ``` #### Snapshot testing This runs all [fixtures](https://github.com/PhilippRados/wrecc/tree/master/tests/fixtures) and compares them to the expected [snapshot](https://github.com/PhilippRados/wrecc/tree/master/tests/snapshots) ``` bash tests/snapshot_tests.sh ``` #### Fuzzer Runs the fuzzer using [afl.rs](https://github.com/rust-fuzz/afl.rs) ``` // in fuzzer directory cargo afl build cargo afl fuzz -i inputs -o outputs target/debug/fuzz_target ``` ## Troubleshooting Reasons for `wrecc` not working properly on your machine: - Unsupported architecture/OS - Cannot find libc in standard library search paths (can be fixed by passing custom search path using `-L ` option) - If it's not mentioned in the [unimplemented features](#unimplemented) section then please raise an issue ## Contribution If you want to help me with this compiler I would really welcome it. The easiest place to start is probably by implementing one of the missing keywords/types mentioned in the [unimplemented features](#unimplemented) section. Make sure all tests still pass and implement your own if it's something new that is not already being tested.
Have a look at the [documentation](https://docs.rs/wrecc_compiler/latest/wrecc_compiler/) to get a high level overview of the compiler pipeline. ## Project goals - Not relying on custom headers - Passing all C99 tests in [c-testsuite](https://github.com/c-testsuite/c-testsuite) - Compiling real-world C projects like [Git](https://github.com/git/git/tree/master) ## Resources The following resources helped me in building this compiler: - [Crafting Interpreters](https://craftinginterpreters.com/) - Engineering a Compiler (Book) - [acwj](https://github.com/DoctorWkt/acwj) - [saltwater](https://github.com/jyn514/saltwater) - [chibicc](https://github.com/rui314/chibicc)