Re: fftw: Usage of SSE in 64bit?

[Julian Taylor <jtaylor.debian@googlemail.com>]

On Wed, Mar 23, 2011 at 3:21 PM, Sylvestre Ledru <sylvestre@debian.org> wrote:
> Le mercredi 23 mars 2011 à 14:52 +0100, Carsten Aulbert a écrit :

> Hi
>
> we are just discussing FFTW in our institute and we hit this bug reported to
> Ubuntu which also holds true for Debian:
>
> https://bugs.launchpad.net/ubuntu/+source/fftw3/+bug/602586
>
> Is there a specific reason why SSE is enabled for 32bit and not enabled for
> 64bit as the difference in performance can easily be a factor of 2 (on 64bit).

This bug is invalid. SSE is enabled by default under amd64 [1]

Sylvestre
[1] http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html
`sse'
[...]
"This is the default choice for the x86-64 compiler."

but it will not define HAVE_SSE in config.h so the fftw3 might not use some handcrafted functions.