wrecc Download - wrecc Source code download

wrecc

C# source code

v0.2.0

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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 assembly in AT&T syntax, it adheres to the 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.

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 which are built directly into the binary

Preprocessor

The preprocessor implements all C99 preprocessor directives, 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

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

Function pointers

#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: %dn", calc.add(10, 5));
  printf("Result of subtraction: %dn", calc.subtract(10, 5));
}

Constant folding

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:

Arrays with unspecified size
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

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
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 code	AST
#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'`

#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 and compares them to the expected snapshot

bash tests/snapshot_tests.sh

Fuzzer

Runs the fuzzer using 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 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 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 to get a high level overview of the compiler pipeline.