Opeth is the optimizer and debug tools for Lua VM bytecode, or Metal band.
Lua VM Bytecode optimizer
luarocks --local install opeth-opeth
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.
$ # 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)
you can use the optimizer in your scripts.
optimizer = require'opeth.opeth'
f = -> ......
f_ = optimizer f
f_!Lua VM Bytecode Control Flow Graph Visualizer
luarocks --local install opeth-lvis
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
Lua VM Bytecode step-by-step execution machine
luarocks --local install opeth-moonstep
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
Lua VM Bytecode Assembly-like Language Compiler
luarocks --local install opeth-lasm
......