Re: [dev] [st] [PATCH 4/3] tresize: remove unnecessary if

From: koneu <koneu93_AT_googlemail.com>
Date: Sun, 12 Apr 2015 11:36:00 +0200

On April 12, 2015 10:56:40 AM CEST, noname_AT_inventati.org wrote:
>On Sun, Apr 12, 2015 at 10:41:36AM +0200, Silvan Jegen wrote:
>> I was thinking about this option too but in that case you would be
>> calling memmove with an identical src and dst when i == 0. The man
>page
>> for glibc memmove(3) does not mention anything about this being a
>noop
>> so I am not sure that is a good thing to do.
>
>"The memory areas may overlap: copying takes place as though the bytes
>in
>src are first copied into a temporary array that does not overlap src
>or dest, and the bytes are then copied from the temporary array to
>dest."
>
>src == dest is just a case of overlapping areas, it must work.

It is not a nop though, but two copy operations. Even with i=0 the function call might be more costly than a simple je.
Received on Sun Apr 12 2015 - 11:36:00 CEST