test/binaryen.js/sieve.js.txt

(module
 (type $i (func (param i32) (result i32)))
 (memory $0 1 100)
 (export "sieve" (func $sieve))
 (func $sieve (; 0 ;) (type $i) (param $0 i32) (result i32)
  (local $1 i32)
  (if
   (i32.lt_u
    (i32.mul
     (current_memory)
     (i32.const 65536)
    )
    (get_local $0)
   )
   (grow_memory
    (i32.sub
     (i32.div_u
      (i32.add
       (get_local $0)
       (i32.const 65535)
      )
      (i32.const 65536)
     )
     (current_memory)
    )
   )
  )
  (set_local $1
   (i32.const 0)
  )
  (loop $clear
   (i32.store8
    (get_local $1)
    (i32.const 0)
   )
   (set_local $1
    (i32.add
     (get_local $1)
     (i32.const 1)
    )
   )
   (br_if $clear
    (i32.eq
     (get_local $1)
     (get_local $0)
    )
   )
  )
  (return
   (get_local $0)
  )
 )
)

optimized:

(module
 (type $i (func (param i32) (result i32)))
 (memory $0 1 100)
 (export "sieve" (func $sieve))
 (func $sieve (; 0 ;) (type $i) (param $0 i32) (result i32)
  (local $1 i32)
  (if
   (i32.lt_u
    (i32.shl
     (current_memory)
     (i32.const 16)
    )
    (get_local $0)
   )
   (grow_memory
    (i32.sub
     (i32.div_u
      (i32.add
       (get_local $0)
       (i32.const 65535)
      )
      (i32.const 65536)
     )
     (current_memory)
    )
   )
  )
  (loop $clear
   (i32.store8
    (get_local $1)
    (i32.const 0)
   )
   (br_if $clear
    (i32.eq
     (tee_local $1
      (i32.add
       (get_local $1)
       (i32.const 1)
      )
     )
     (get_local $0)
    )
   )
  )
  (get_local $0)
 )
)