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Re: Function Multiversioning in GCC6
On Thu, Mar 23, 2017 at 4:45 AM, O Mahony, Billy
<billy.o.mahony@intel.com> wrote:
>
> Hi Xi,
>
> Thanks for the clarification/confirmation.
>
> Regards,
> Billy.
>
> > -----Original Message-----
> > From: Xi Ruoyao [mailto:ryxi@stu.xidian.edu.cn]
> > Sent: Thursday, March 23, 2017 9:21 AM
> > To: O Mahony, Billy <billy.o.mahony@intel.com>
> > Cc: ryxi@stu.xidian.edu.cn; gcc-help@gcc.gnu.org
> > Subject: Re: Function Multiversioning in GCC6
> >
> > On 2017-03-22 10:51 +0000, O Mahony, Billy wrote:
> >
> > > However when I compile the first example in this LWN article
> > > https://lwn.net/Articles/691932/ with gcc-6 C compiler it fails with
> > > (error: redefinition of
> > > 'foo'...) .
> >
> > The document <https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/Function-
> > Multiversioning.html> said:
> >
> > With the GNU *C++* front end, for x86 targets, you may specify multiple
> > versions of the function.
> >
> > FMV doesn't work with C FE. In C, __attribute__((target("sse4.2"))) just
> > means to compile this function with -msse4.2, see
> > <https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/Common-Function-
> > Attributes.html>.
> >
> > --
> > Xi Ruoyao <ryxi@stu.xidian.edu.cn>
> > School of Aerospace Science and Technology, Xidian University
>
You can also read this LWN article:
https://lwn.net/Articles/691932/