pe1.wat

(module
  (import "console" "log" (func $console_log (param $val i32)))
  (export "pe1" (func $pe1))
  (func $pe1
    (result i32)
    (local $n i32)
    (local $sum i32)
    
    (set_local $sum (i32.const 0))
    (set_local $n (i32.const 3))
    
    loop $ml
      block $bad
      block $good
      
      ;; goto $good if n % 3 == 0
      (br_if $good
        (i32.eq
          (i32.rem_u (get_local $n) (i32.const 3))
          (i32.const 0)
        )
      )
      
      ;; goto $good if n % 5 == 0
      (br_if $good
        (i32.eq
          (i32.rem_u (get_local $n) (i32.const 5))
          (i32.const 0)
        )
      )
      
      ;; no match, goto $bad
      br $bad
      
      end $good
      
      ;; inc sum
      (set_local $sum
        (i32.add (get_local $sum) (i32.const 1))
      )
      
      end $bad
      
      ;; inc n and maybe loop
      (tee_local $n
        (i32.add (get_local $n) (i32.const 1))
      )
      (br_if $ml (i32.lt_u (i32.const 10000)))
    end $ml
    
    (call $console_log (get_local $sum))
    
    get_local $sum
  )
)