On Sun, Apr 12, 2015 at 11:35:42AM +0200, Silvan Jegen wrote: > I just wonder if it really will be copying the data around into a > temporary array for no reason when i == 0 (either in glibc or in another > libc).
Well, it does not really move data to temporary array, memmove just chooses the right direction so it does not destroy data. glibc indeed wastes CPU cycles if dst == src, However, musl does not: http://git.musl-libc.org/cgit/musl/tree/src/string/memmove.c
