C Minus is a very simple language which we implemented the frontend and IR generator of it in Python with a self made IR here for the project of compiler course in Sharif University of Technology, lectured by Dr. Ghasemsani. However, because the IR was a self made thing, we could only run it via an interpreter. Instead, I challenged myself to write the project in Flex/Bison/LLVM in order to learn them and have fun.
To compile this compiler, you need Flex, Bison and LLVM-15. You can get them all with the following command in Ubuntu/Debian:
apt install flex bison clang-15 llvm-15 build-essential g++-12Note: You might also need g++-12 because llvm-15 uses it.
Then simply execute make command to build the compiler. The compiler will accept the input source filename as the first argument. This will cause the IR to be outputted in the stdout. If you want it to be outputted in a file, you can pass the output filename as the second argument.
The IR can be compiled with clang-15 output.ll command to an executable.
Tests can be run via make verify-all command. If any of the tests fail, the testing will stop on that test. Otherwise, a green message that reads All tests passed! will appear. Tests are simply just an input program and an expected output that should be generated after the program is ran.
Currently, the compiler does not have an semantic analyzer which means that most of errors are either not caught at all or result in an assertion failure that results in compiler aborting.
Literally the amount of optimizations done for the IR is fucking zero. Even the constant folding is turned off. You can turn on the constant folding by changing the_builder initialization with this line:
builder(std::make_unique<llvm::IRBuilder<llvm::NoFolder>>(*the_context))The language specification (the assignments) is placed in the spec folder.
Alongside the specification, there is also an addition: The input() function. This function will simply read an integer from stdin. For example, this program can be used to calculate the square of a number:
int main(void){
int a;
a = input();
output(a * a);
}