Re: [Sbcl-devel] [Sbcl-commits] master: Improve STRING= on x86[-64] by using memcmp() sometimes.

[James Y K. <fo...@fu...>]

So what if some platforms *might* have a crappy memcmp? They should improve it, of course, it affects all other software as well...

And if some platform *is* shown to have a 70x slower memcmp and anyone cares, change it for that platform, at that point?

On July 8, 2014 3:02:56 PM EDT, Stas Boukarev <sta...@gm...> wrote:
>"Douglas Katzman" <sn...@us...> writes:
>
>> The branch "master" has been updated in SBCL:
>>        via  956aa35502b93740679842bb38f50481777c0b08 (commit)
>>       from  7354854c14241b7d8def7ab4953257e55f3c00f7 (commit)
>>
>> - Log
>-----------------------------------------------------------------
>> commit 956aa35502b93740679842bb38f50481777c0b08
>> Author: Douglas Katzman <do...@go...>
>> Date:   Mon Jul 7 23:34:57 2014 -0400
>>
>>     Improve STRING= on x86[-64] by using memcmp() sometimes.
>>     
>>     Also the unequal length pre-test, like in STRING-EQUAL, was
>missing.
>>     
>>     This benchmarked twice as fast for strings of 20 characters in
>length
>>     on two different pieces of hardware and approached 70x for huge
>strings.
>>     
>>     Hopefully it will not be ruined with Unicode normalization, which
>>     presumably occurs on creation of strings, not in every call to
>string=.
>I really don't like calling foreign functions for lisp code like that.
>It's something that can't be controlled, there's no guarantee that it's
>actually faster on all supported OSes.
>The cut off point appears to be based on some particular implementation
>of memcmp.
>
>-- 
>With best regards, Stas.
>
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