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From: Joakim Sindholt <opensource@zhasha.com>
To: musl@lists.openwall.com
Subject: Re: byteswap.h
Date: Fri, 7 Apr 2017 20:07:42 +0200	[thread overview]
Message-ID: <20170407180742.GB8704@wirbelwind> (raw)
In-Reply-To: <225ea64f-f051-1a61-0ba2-db9f27d1ba68@gmail.com>

On Fri, Apr 07, 2017 at 07:53:09PM +0200, fab10 wrote:
> I had a look at byteswap.h and it seems to me that the code is not very 
> efficient. Every function in this header could be translated in a single 
> assembly instruction with the gcc intrinsics:
> 
> __builtin_bswap16
> __builtin_bswap32
> __builtin_bswap64
> 
> Is there a reason to not use these gcc intrinsics?
> 
> Bye
> 

While musl does employ GNU C features in quite a few places it's just
plain unnecessary here.

https://godbolt.org/g/eLZWwI

When optimized those functions yield a single bswap instruction anyway,
because GCC is smart enough to deduce this.


  parent reply	other threads:[~2017-04-07 18:07 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-07 17:53 byteswap.h fab10
2017-04-07 17:55 ` byteswap.h Jon Chesterfield
2017-04-07 18:01 ` byteswap.h Rich Felker
2017-04-07 18:07 ` Joakim Sindholt [this message]
2017-04-08 14:57   ` byteswap.h Szabolcs Nagy

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