memcpy vs slice copy

[bearophile]

Don:
>Which means that memcpy probably isn't anywhere near optimal, either.<

Time ago I have read an article written by AMD that shows that indeed with modern CPUs there are ways to go much faster, using vector asm instructions, loop unrolling and explicit cache prefetching (but it's useful with longer arrays only. Profile-driven optimization can tell you if a particular copy usually copies lot of data, and use such kind of copy, that is overkill/slow/too much code for the cache for smaller copies. As an alternative the programmer may add some annotation to choose what copy strategy to use, but this is not nice).

Bye,
bearophile