https://github.com/georgesittas/minijava-compiler
MiniJava to LLVM IR compiler
https://github.com/georgesittas/minijava-compiler
compiler java jflex-cup jtb llvm minijava minijava-compiler visitor-pattern
Last synced: about 1 month ago
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MiniJava to LLVM IR compiler
- Host: GitHub
- URL: https://github.com/georgesittas/minijava-compiler
- Owner: georgesittas
- Created: 2021-09-22T10:51:13.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2023-03-09T02:32:56.000Z (about 2 years ago)
- Last Synced: 2025-03-24T21:05:17.872Z (about 2 months ago)
- Topics: compiler, java, jflex-cup, jtb, llvm, minijava, minijava-compiler, visitor-pattern
- Language: LLVM
- Homepage:
- Size: 834 KB
- Stars: 14
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# MiniJava Compiler
This is a [MiniJava](https://cgi.di.uoa.gr/~compilers/20_21/project.html#hw2) compiler that targets LLVM,
written in Java with the help of JFlex, JavaCUP and JTB.
I would like to thank [Stefanos Baziotis](https://github.com/baziotis) for contributing his [MiniJava
testsuite](https://github.com/baziotis/minijava-testsuite)!
## Usage
```bash
# Compile the project
make
# Run the compiler
java Main file1 [file2 [file3 ...]]
# Cleanup
make clean
```
## Implementation
### Scoping & Symbol Table
MiniJava is a simple language when it comes to scoping: all declarations precede statements.
This property prevents declarations from showing up in nested compound statements such as
if-else, while and block statements. Thus, the symbol table need only keep track of class
declarations, class-scoped declarations (i.e. fields and methods) and method-scoped declarations
(i.e. formal parameters and local variables).
### Compilation Phases
We start by producing an AST for the source program with the help of JFlex, JavaCUP and JTB. Then,
we check its semantics & finally generate the LLVM IR code with the help of the following visitor
classes:
1. `STVisitor` populates the symbol table
2. `SCVisitor` type checks the program
3. `VTVisitor` populates the virtual method table
4. `CGVisitor` generates the resulting LLVM IR code
### Notes
- The `MainClass` class and its `main` method are not handled as special cases. The method's
argument is stored in the symbol table with type `String[]`, so, if it appears in any
expression in the program, a type error will be triggered by `SCVisitor` inevitably.
- Scopes are implemented by constructing strings of the form `ClassID [":" [MethodID]]` and passing
them as arguments to children nodes as the visitors are walking the AST.
- LLVM-IR code virtual registers are assigned names of the form `%_number`, where `number` is an
auto-incrementing integer.