PL/0 JIT compiler

A tiny PL/0 JIT compiler in less than 900 LOC with LLVM and PEG parser. It features runtime error handling for division by zero using C++ exception handling via LLVM IR, and supports nested procedures with free variable capture.

Library dependencies:

• Parsing and AST: cpp-peglib
• JIT Compilation: LLVM (ORC JIT / LLJIT)

Build on macOS

brew install llvm
export PATH="$PATH:$(brew --prefix llvm)/bin"
make

Usage

> ./pl0 samples/square.pas
1
4
9
16
25
36
49
64
81
100

Use -emit-llvm to dump the generated LLVM IR:

> ./pl0 samples/square.pas -emit-llvm

Sample programs

Square (samples/square.pas)

VAR x, squ;

PROCEDURE square;
BEGIN
   squ := x * x
END;

BEGIN
   x := 1;
   WHILE x <= 10 DO
   BEGIN
      CALL square;
      ! squ;
      x := x + 1
   END
END.

Nested procedures with free variables (samples/nested-functions.pas)

VAR x;
  PROCEDURE func0;
    VAR x0;
    PROCEDURE func1;
      VAR x1;
    BEGIN
      x1 := 789;
      out x;
      out x0;
      out x1;
    END;
  BEGIN
    x0 := 456;
    CALL func1
  END;
BEGIN
  x := 123;
  CALL func0
END.

Benchmark with Fibonacci number [0, 35)

> make bench
*** Python ***
real	0m8.367s
user	0m8.153s
sys	0m0.129s

*** Ruby ***
real	0m3.064s
user	0m2.916s
sys	0m0.097s

*** PL/0 ***
real	0m0.249s
user	0m0.234s
sys	0m0.008s

License

MIT