[PATCH][BZ #16004] Check overlaps in memcpy_chk.

[Ondřej Bílka]

On Fri, Oct 25, 2013 at 02:26:40PM -0700, Roland McGrath wrote:
> > Hi, this adds a overlap check to memcpy. As these are not performance
> > critical I deleted ifuncs and we instead do jump to memcpy.
> 
> I don't think it's at all clear that _FORTIFY_SOURCE wrappers are not
> performance critical.  Lots of systems nowadays are compiling most of
> their stuff this way (e.g. Ubuntu and Gentoo the compiler does it by
> default; Fedora et al the package system builds do it by default).

A checked now strcpy is four times slower than normal one. This has much
bigger effect than few extra cycles from overlap checking.

Most of other *_chk functions are also slow but we did not measured how.