On 10 November 2010 17:25, Jed Brown <j...@59a2.org> wrote: > > Is the memcpy-back code ever executed when called as memcpy()? I can't > imagine why it would be, but it would make plenty of sense to use it inside > memmove when the destination is at a higher address than the source. > Jed
Oh yes. And, after further reading, it seems I'm not alone. There's an article at http://lwn.net/Articles/414467/ about the new glibc changes and a bug at https://bugzilla.redhat.com/show_bug.cgi?id=638477 relating directly to memcpy. The Fedora bug is particularly insightful with some interesting contributions from Linus Torvalds himself, amongst other. In short, someone from Intel submitted a glibc patch that does faster memcpy's on e.g. Intel i7, respects the ISO C definition, but does things backwards. I think any software that ignores the ISO warning "If copying takes place between objects that overlap, the behavior is undefined" needs fixing.
