m2lang - The LLVM-based Modula-2 compiler

Introduction

See this FOSDEM 2019 talk for some details.

Implementation decisions

• LLVM is only external dependency
• CMake scripts derived from clang
• ISO Modula-2 language first
• Use "declare-before-use" (single-pass) model
• Goal is target several platforms from the beginning

Current status

• The lexer is done.
• The preprocessor (for handling of directives) is is based on the draft technical report "Interfacing Modula-2 to C", Annex B and aims to be compatible to the Macintosh p1 compiler. Parsing of directives is implemented, with mostly no functionality.
• The parser is based on ISO Modula-2 with generic and OO additions. Some LL(1) conflicts are still left in the grammar, so not every source is parsed correctly.
• The parser is generated by LLtool. A C++ port of LLtool is now integrated into this project, but not yet enabled.
• Error recovery in the parser is based on "panic mode", using the follow sets of the current and the active callers.
• The AST nodes are generated by ASTtool.
• Error messages are outputted using llvm::SourceMgr for nice presentation.
• Only a dummy driver exists to see the parser in action.
• A couple of IR statements is emitted to the console after succesful parsing.