[erlang-questions] native

Yiannis Tsiouris <>
Mon Sep 10 15:13:16 CEST 2012


On 09/10/2012 03:41 PM, Thomas Lindgren wrote:
>> I started playing with a simple implementation of MD5 (basically
straight from the wiki page)
>> When the implementation produce the correct output, I did some timing
for fun and also
>> tried to native compile it.
>> To my astonishment I discovered that the code was slower when native
compiled.
>> I am using R15B01 on mac. Can this be true? And in this case why?
>>
>> Note that I do not care to optimize the implementation it self! I am
more interested why
>> the native compiler produce slower code on this example.
>
>
> On my Mac, the best native result 7% is faster than the best beam
result. But the timing varies by 20% from run to run, so I think the
proper claim is they are about the same. (I also think Hipe ought to
comfortably beat Beam on this sort of code.)
>
> Unfortunately, 'pp_native' gave broken/confusing output so it's hard to
trace what happens. The arithmetic looks like it's being inlined, which
ought to provide a boost. There are calls to r/1 and rotate/2 in the
inner loop (md5_/6) which possibly should have been inlined.
Hi,

Could you post the testcase that you 're timing?


Best,
Yiannis

-- 
Yiannis Tsiouris
Ph.D. student,
Software Engineering Laboratory,
National Technical University of Athens
WWW: http://www.softlab.ntua.gr/~gtsiour

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