Compiler developed mostly in C for the compilers course at National Technical University of Athens (year 2019).
PCL is an imperative programming language resembling the Pascal programming language. It's full documentation can be found in pcl2019.pdf.
This tools used for the development of this compiler are:
This project was built with the following tools:
- g++ version 7.5.0
- clang version 11.0.0
- llvm version 11.0.0
- python version 3.6.9
- flex version 2.6.4
- bison version 3.0.4
Installation can be achieved by cloning this repository and running make on the main directory.
After running make one can use the python script pcl to invoke the compiler as follows:
./pcl <options>can be just a filename with some extension, in which case an llvm IR file is created along with an assembly one, with the extensions 'imm' and 'asm' respectively.
For a full listing of the available options run:
./pcl -hThe compiler consists of 5 parts executed consequently:
- Lexing, which is implemented in file lexer.l using flex.
- Parsing, which is implemented in file parser.y using bison, while also creating an Abstract Syntax Tree (ast).
- Type Checking, which is implemented in file ast.c in function type_check.
- Function Parameters Fixing. This part was necessary due to the use of LLVM IR, which does not support nested scopes, nor allows direct access to the stack frames. In this part each function that uses a variable defined in an outer scope gets this variable passed as a parameter by reference. For this reason, the function make_params in file make_params.cpp is called to alter the ast. As this language supports mutual recursion, make_params is a fix point computation.
- LLVM IR emission, which is implemented in file code_gen.cpp. In this file, optimizations to the IR code are also included.
The following bonus parts are implemented:
- Reals
- Optimizations of IR code
- Register allocation and final code optimizations