Opeth

Opeth is the optimizer and debug tools for Lua VM bytecode, or Metal band.

tools

opeth

Lua VM Bytecode optimizer

install

luarocks --local install opeth-opeth

usage

Usage: opeth [-o <output>] [-V] [-T] [-v] [--show-optimizations] [-h]
       <input> [-x index [index] ...]

Lua VM Bytecode Optimizer

Arguments:
   input                 luac file

Options:
   -o <output>, --output <output>
                         output file (default: optimized.out)
   -x index [index] ..., --disable-optimize index [index] ...
                         disable a part of optimizer
   -V, --verbose         verbose optimization process
   -T, --time            measure the time
   -v, --version         version information
   --show-optimizations  show a sort of otimization
   -h, --help            Show this help message and exit.

example

$ # Show the optimization techniques. The order corrensponds to the index which needs to `--disable-optimize` option.
$ opeth --show-optimizations
unreachable blocks removal : remove all the blocks which are unreachable for the top
constant fold              : evaluate some operations beforehand
constant propagation       : replace `MOVE` instruction with the another
dead-code elimination      : eliminate the instructions which aren't needed
function inlining          : expand a funcion call with the function's instructions
$
$ opeth luac.out -o optimized.out
$
$ opeth luac.out -o optimized.out --verbose --time
read from luac.out (size: 226 byte, time: 0.79703330993652 msec)
unreachable blocks removal#main: 0 modified
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 2 modified
unreachable blocks removal#main: 3 modified
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 1 modified
unreachable blocks removal#main: 0 modified
constant fold#main: 0 modified
constant propagation#main: 1 modified
dead-code elimination#main: 0 modified
unreachable blocks removal#main: 0 modified
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 0 modified
unused resources removal#main: 3 modified
(optimize time: 3.058910369873 msec)
change of the number of instructions: 11 -> 5

write to optimized.out (size: 110 byte, time: 0.25796890258789 msec)
$
$ # optimize without the op-technique which the index points to.
$ opeth luac.out -o optimized.out --verbose --time --disable-optimize 1
read from luac.out (size: 226 byte, time: 0.7932186126709 msec)
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 2 modified
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 1 modified
constant fold#main: 0 modified
constant propagation#main: 1 modified
dead-code elimination#main: 0 modified
constant fold#main: 0 modified
constant propagation#main: 0 modified
dead-code elimination#main: 0 modified
unused resources removal#main: 2 modified
(optimize time: 3.7388801574707 msec)
change of the number of instructions: 11 -> 8

write to optimized.out (size: 129 byte, time: 0.32711029052734 msec)

optimize functions inscripts

you can use the optimizer in your scripts.

optimizer = require'opeth.opeth'

f = -> ......
f_ = optimizer f
f_!

lvis

Lua VM Bytecode Control Flow Graph Visualizer

install

luarocks --local install opeth-lvis

usage

example

Supporse think about the lua code and following bytecode.

local x = 3

if x < 5 then
	print("hello")
else
	print("world")
end

        1       [1]     LOADK           0 -1    ; 3
        2       [3]     LT              0 0 -2  ; - 5
        3       [3]     JMP             0 4     ; to 8
        4       [4]     GETTABUP        1 0 -3  ; _ENV "print"
        5       [4]     LOADK           2 -4    ; "hello"
        6       [4]     CALL            1 2 1
        7       [4]     JMP             0 3     ; to 11
        8       [6]     GETTABUP        1 0 -3  ; _ENV "print"
        9       [6]     LOADK           2 -5    ; "world"
        10      [6]     CALL            1 2 1
        11      [7]     RETURN          0 1

Given a bytecode,

$ lvis luac.out

lvis outputs the pdf

moonstep

Lua VM Bytecode step-by-step execution machine

install

luarocks --local install opeth-moonstep

usage

commands in dialogue

command:
        bp <pc>: set a breakpoint to <pc>
        r: run the code. if the breakpoint is set, stop at <pc>
        n: execute the next instruction
        d: dump the current register and PC
        dp: dump the bytecode structure
        q: quit

lasmc

Lua VM Bytecode Assembly-like Language Compiler

install

luarocks --local install opeth-lasm

syntax

......

dependencies

• MoonScript
• luasocket
• argparse
• lua-graphviz
• inspect.lua

reference

https://nymphium.github.io/pdf/opeth_report.pdf

LICENSE

MIT