https://github.com/n-shevko/modula2

Compiler for tiny subset of Modula 2
https://github.com/n-shevko/modula2

compiler-enginnering llvm-ir peg-parser

Last synced: about 1 year ago
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Compiler for tiny subset of Modula 2

• Host: GitHub
• URL: https://github.com/n-shevko/modula2
• Owner: n-shevko
• Created: 2024-08-15T17:59:00.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-08-15T22:53:03.000Z (almost 2 years ago)
• Last Synced: 2025-02-06T09:19:14.860Z (over 1 year ago)
• Topics: compiler-enginnering, llvm-ir, peg-parser
• Language: F#
• Homepage:
• Size: 43.9 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
Compiler for tiny subset of Modula 2.

It was done to learn basics of compiler engineering.

LLVM IR was used as a target language.

### What was done

1. [Peg packrat parser generator](https://en.wikipedia.org/wiki/Packrat_parser)

   It consumes file like [this](https://github.com/n-shevko/modula2/blob/main/modula_2/grammar.txt)

   and generates:

   - ast type definitions like [these](https://github.com/n-shevko/modula2/blob/main/modula_2/RawAst.fs)

   - parser file like [this](https://github.com/n-shevko/modula2/blob/main/modula_2/Parser.fs)

   The result parser file has function parse which can parse source code and generate ast object. 

   Parser generator supports basic quantifiers like: *+?

   Nonterminal in {} means that it is entry point (top level) nonterminal.

2. Ast [->](https://github.com/n-shevko/modula2/blob/main/modula_2/Cfg.fs) CFG pass 

   

3. CFG [->](https://github.com/n-shevko/modula2/blob/main/modula_2/Ssa.fs) CFG in SSA form pass.

   Inspired by "Simple and Efficient Construction of Static Single Assignment Form (Braun)"

### Known issues

- Compiler doesn't have any garbage collection

- Implemented only arrays, structs, integers. 

- Elimination of left recursion from grammar works only if left recursion appears in the first branch

- Syntax error reports are incomprehensible :) [This](https://github.com/n-shevko/modula2/blob/main/parser/ReportSyntaxErrors.fs) thing should be definitely rewritten 

### Other

Any modification of an array\structure copy entire agregate and then modify only needed subelement. 

This is done on purpose for potential CPS conversion in the future.