[LAD] vectorization

[Christian Schoenebeck]

We also played around with GCC's vector extensions years ago. Here's a pointer 
to one of many discussions we had:

	https://bugs.linuxsampler.org/cgi-bin/show_bug.cgi?id=25

One of the main problems we had, is that there's no way to access the 
individual "cells" / members of the vector effectively:

	http://gcc.gnu.org/ml/gcc-help/2006-04/msg00178.html

Not sure if that changed in the meantime, but somehow I doubt it. :)

CU
Christian

Am Donnerstag, 7. Februar 2008 17:51:06 schrieb Malte Steiner:
> Hello,
>
> I try to squeeze as much performance as possible out of my upcomming
> Linux synthesizer and try manual vectorization with following construct
> in c, mainly to vectorize away multiplications :
>
> typedef float v4sf __attribute__ ((vector_size(16)));
>
> union f4vector
> {
>    v4sf v __attribute__((aligned (16)));
>    float f[4] __attribute__((aligned (16)));
> };
>
> On AMD 64bit Turion (single core) on 64 Studio in 64bit mode this doesnt
> improve performance at all, actually it even get worse. Is GCC that good
> at optimizing on its own? I have no access to Intel processors at the
> moment but would love to know how to benefit from SIMD optimizations of
> float operations.
> Sources on the web are rather thin...
>
> Cheers,
>
> Malte