Lilc

A hand-written compiler for a small, C-like language, targeting LLVM and built for learning purposes.

Currently Implemented Grammar

Just for reference, as the parser is implemented by hand. Nonterminals defined in token.h

program => block
block => expr_stmt+
expr_stmt =>
    expr SEMI
funcdef =>
    DEF ID LPAREN ID {COMMA ID} RPAREN LCURL block RCURL
call =>
    ID LPAREN (params | E) RPAREN
params =>
    params, id |
    id
if =>
    IF LPAREN expr RPAREN LCURL block RCURL elif* else?
elif =>
    ELSE IF LPAREN expr RPAREN LCURL block RCURL
else =>
    ELSE LCURL block RCURL
expr =>
    expr CMPLT term0 |
    term0            |
    call             |
    funcdef          |
    if
term0 =>
    term0 ADD term1   |
    term0 SUB term1   |
    term1
term1 =>
    term1 MUL term2 |
    term1 DIV term2 |
    term2
term2 =>
    DBL{DBL} |
    LPAREN expr RPAREN

Start Symbol: program

Todo

• Mutable variables
• “Return” keyword
• Optional 'else'
• Nested if/else
  • It seems like it kinda works as is but the IR is super unreadable b/c of the way I eagerly insert blocks in if_codegen.
• For loop
• While loop
• Block scoping w/ corresponding semantic analysis
• Rest of comparison operators
• Allow semicolon omission from everything except for statements in user-defined blocks
• Comments (skip to \n)
• Other types, constants w/ corresponding semantic analysis, flesh out type system
• Structs
• Module system
• Screw LLVM-C, emit LLVM IR directly
• Screw LLVM IR emit x86 directly
• Screw compilers write a stack VM