Given the useless program useless.wat:
(module
(func $i32binop
i32.const 21
i32.const 21
i32.add
i32.const 0
drop
drop
i32.const 63
i32.const 21
i32.sub
i32.const 0
drop
drop
i32.const 21
i32.const 2
i32.mul
i32.const 0
drop
drop
i32.const 84
i32.const 2
i32.div_s
i32.const 0
drop
drop
i32.const 84
i32.const 2
i32.div_u
i32.const 0
drop
drop
i32.const -42
i32.const 4
i32.rem_s ;; 4*10 + 2 > =-2
i32.const 0
drop
drop
i32.const -42
i32.const 4
i32.rem_u ;; 4*10 + 2 > =2
i32.const 0
drop
drop
i32.const 1
i32.const 3
i32.and ;; bitwise ope > =1
i32.const 0
drop
drop
i32.const 1
i32.const 3
i32.or ;; bitwise ope > =3
i32.const 0
drop
drop
i32.const 1
i32.const 3
i32.xor ;; bitwise ope > =2
i32.const 0
drop
drop
i32.const 1
i32.const 3
i32.shl ;; shift left ope > =8
i32.const 0
drop
drop
i32.const 8
i32.const 3
i32.shr_u ;; shift right ope > =1
i32.const 0
drop
drop
i32.const 8
i32.const 3
i32.shr_s ;; shift right ope > =1
i32.const 0
drop
drop
i32.const 1
i32.const 3
i32.rotl ;; rotation left ope > =8
i32.const 0
drop
drop
i32.const 8
i32.const 3
i32.rotr ;; rotation left ope > =1
i32.const 0
drop
drop
)
(func $i64binop
i64.const 21
i64.const 21
i64.add
i32.const 0
drop
drop
i64.const 63
i64.const 21
i64.sub
i32.const 0
drop
drop
i64.const 21
i64.const 2
i64.mul
i32.const 0
drop
drop
i64.const 84
i64.const 2
i64.div_s
i32.const 0
drop
drop
i64.const 84
i64.const 2
i64.div_u
i32.const 0
drop
drop
i64.const -42
i64.const 4
i64.rem_s ;; 4*10 + 2 > =-2
i32.const 0
drop
drop
i64.const -42
i64.const 4
i64.rem_u ;; 4*10 + 2 > =2
i32.const 0
drop
drop
i64.const 1
i64.const 3
i64.and ;; bitwise ope > =1
i32.const 0
drop
drop
i64.const 1
i64.const 3
i64.or ;; bitwise ope > =3
i32.const 0
drop
drop
i64.const 1
i64.const 3
i64.xor ;; bitwise ope > =2
i32.const 0
drop
drop
i64.const 1
i64.const 3
i64.shl ;; shift left ope > =8
i32.const 0
drop
drop
i64.const 8
i64.const 3
i64.shr_u ;; shift right ope > =1
i32.const 0
drop
drop
i64.const 8
i64.const 3
i64.shr_s ;; shift right ope > =1
i32.const 0
drop
drop
i64.const 1
i64.const 3
i64.rotl ;; rotation left ope > =8
i32.const 0
drop
drop
i64.const 8
i64.const 3
i64.rotr ;; rotation left ope > =1
i32.const 0
drop
drop
)
(func $f32binop
f32.const 21
f32.const 21
f32.add
i32.const 0
drop
drop
f32.const 63
f32.const 21
f32.sub
i32.const 0
drop
drop
f32.const 21
f32.const 2
f32.mul
i32.const 0
drop
drop
f32.const 84
f32.const 2
f32.div
i32.const 0
drop
drop
f32.const 42
f32.const 21
f32.max
i32.const 0
drop
drop
f32.const 42
f32.const 84
f32.min
i32.const 0
drop
drop
f32.const -42
f32.const 21
f32.copysign
i32.const 0
drop
drop
)
(func $f64binop
f64.const 21
f64.const 21
f64.add
i32.const 0
drop
drop
f64.const 63
f64.const 21
f64.sub
i32.const 0
drop
drop
f64.const 21
f64.const 2
f64.mul
i32.const 0
drop
drop
f64.const 84
f64.const 2
f64.div
i32.const 0
drop
drop
f64.const 42
f64.const 21
f64.max
i32.const 0
drop
drop
f64.const 42
f64.const 84
f64.min
i32.const 0
drop
drop
f64.const -42
f64.const 21
f64.copysign
i32.const 0
drop
drop
)
(func $start
call $i32binop
call $i64binop
call $f32binop
call $f64binop
)
(start $start)
)Owi is able to get rid of most of the code:
$ owi opt useless.wat
(module
(type (sub final (func)))
(func $i32binop
)
(func $i64binop
)
(func $f32binop
)
(func $f64binop
)
(func $start
call 0
call 1
call 2
call 3
)
(start 4)
)$ owi opt --help=plain
NAME
owi-opt - Optimize a module
SYNOPSIS
owi opt [--debug] [--output=FILE] [--unsafe] [OPTION]… ARG
OPTIONS
-d, --debug
debug mode
-o FILE, --output=FILE
Write output to a file.
-u, --unsafe
skip typechecking pass
COMMON OPTIONS
--help[=FMT] (default=auto)
Show this help in format FMT. The value FMT must be one of auto,
pager, groff or plain. With auto, the format is pager or plain
whenever the TERM env var is dumb or undefined.
--version
Show version information.
EXIT STATUS
owi opt exits with:
0 on success.
123 on indiscriminate errors reported on standard error.
124 on command line parsing errors.
125 on unexpected internal errors (bugs).
BUGS
Email them to <[email protected]>.
SEE ALSO
owi(1)