calx_vm

Calx VM

Calcit runner can be slow being a dynamic language. Calx VM trying to provide some helper tools for faster computation of very simple but repeated tasks. Ideally Calcit should use WASM for CPU heavy computations.

Usages

cargo install calx-vm
calx hello.cirru

it starts with a main function:

fn main ()
  const 1
  call demo
  const 0
  call demo

fn demo (($a i64) ->)
  local.get $a

  if (->)
    do
      const 11
      echo
    do
      const 20
      echo
  const 3
  echo

-s to show instructions:

$ calx demos/if.cirru -s
[calx] start preprocessing
loaded fn: CalxFunc main (-> )
  00 Const(I64(1))
  01 Call("demo")
  02 Const(I64(0))
  03 Call("demo")

loaded fn: CalxFunc demo (I64 -> )
  local_names: 0_$a .
  00 LocalGet(0)
  01 JmpIf(5)
  02 Const(I64(20))
  03 Echo
  04 Jmp(8)
  05 Const(I64(11))
  06 Echo
  07 Jmp(8)
  08 Const(I64(3))
  09 Echo

[calx] start running
11
3
20
3
[calx] took 67.250µs: Nil

--emit-binary filename for encode functions into a binary file.

--eval-binary for reading a binary input file to run.

Syntax Sugar

Code of:

fn main ()
  i.add
    const 1
    i.mul
      const 2
      const 3

  echo
    dup

  assert "|expected 7"
    i.eq
      const 7

is desugared to:

fn main ()
  const 2
  const 3
  i.mul
  const 1
  i.add

  dup
  echo

  const 7
  i.eq
  assert "|expected 7"

Instructions

Find docs on https://docs.rs/calx_vm/ .

Highly inspired by:

• WASM https://github.com/WebAssembly/design/blob/main/Semantics.md
• Lox https://github.com/Darksecond/lox/blob/master/lox-vm/src/bettervm/vm.rs

Preprocess

Before Calx running the instructions, Calx performs preprocessing to them. There are several tasks:

• block and loop are expanded since there are block-end instructions
• br and br-if also expanded to jmp and jmp-if instructions, internally
• stack size is checked to ensure it's consistent among branches, and tidied up at function end
• local variables are renamed to indexes

The codebase would be updated as I'm learning more about WASM.

License

MIT