Re: [Caml-list] Benchmark: ref update vs argument passing

["Marcin 'Qrczak' Kowalczyk" <qrczak@knm.org.pl>]

Wed, 21 Nov 2001 01:35:53 +0300 (MSK), malc <malc@pulsesoft.com> pisze:

>> let use_refs' time =
>>   let rif = ref 0 in
>>   for i = 0 to time - 1 do rif := !rif + 1 done;
>>   !rif
> let use_refs' time =
>   let rif = ref 0 in
>   for i = 0 to pred time do incr rif done;
>   !rif

The generated code is exactly the same :-P

But none of the following produces optimal code (judging by looking
at the generated code):

let current = ref 0
let next1 () = let x = !current in incr current; x
let next2 () = let x = !current in current := x + 1; x
let next3 () = incr current; !current
let next4 () = let x = !current + 1 in current := x; x

Moreover, making the counter private on the declaration level:

let next1 =
  let current = ref 0 in
  fun () -> let x = !current in incr current; x

yields worse code, even though the semantics is the same.

-- 
 __("<  Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/
 \__/
  ^^
QRCZAK

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