GCC Vector Extensions

Andrew Haley aph@gcc.gnu.org
Tue Apr 18 10:04:00 GMT 2006


Christian Schoenebeck writes:
 > Es geschah am Friday, 7. April 2006 22:17 als Greg Buchholz schrieb:
 > > Christian Schoenebeck wrote:
 > > > b) We wondered [2] what the currently best way is to access single
 > > > elements of one vector. Currently the only solution we saw is to use a
 > > > union trick
 > >
 > > /* I don't know if this qualifies as good, but here's some things
 > >    I've used before  */
 > 
 > Oh, it officially qualified as good! We just made some benchmarks
 > [1] to compare our old union trick vs. your straight forward type
 > casts and your solutions were always faster, often even quite a
 > lot. So as we thought, gcc doesn't like that union thing very much.

It's not legal C, though.  The _mm_load, _mm_set, and _mm_store
operations are provided to do the conversions.

Andrew.



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