test/binaryen.js/hello-world.js.txt

(module
 (type $iii (func (param i32 i32) (result i32)))
 (memory $0 0)
 (export "adder" (func $adder))
 (func $adder (type $iii) (param $0 i32) (param $1 i32) (result i32)
  (return
   (i32.add
    (get_local $0)
    (get_local $1)
   )
  )
 )
)

optimized:

(module
 (type $iii (func (param i32 i32) (result i32)))
 (memory $0 0)
 (export "adder" (func $adder))
 (func $adder (type $iii) (param $0 i32) (param $1 i32) (result i32)
  (i32.add
   (get_local $0)
   (get_local $1)
  )
 )
)

binary size: 82

[object WebAssembly.Instance]

an addition: 42