http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55645
--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> 2012-12-11 10:03:27
UTC ---
(In reply to comment #0)
> // possible syntax
> void compute() {
> for (int i=0;i!=1024;++i) {
> if likely(a[i]<b[i]) // very often
> c[i]=a[i]+b[i];
> else // rare
> c[i]=a[i]-b[i];
> }
> }
You may want to make the rare computation more expensive than that, I am not
sure there is a real speed improvement here (mask+compare+branch might take
about as long as minus+blend).
Interesting idea. First step would be to create a REDUC_TRUTH_AND_EXPR or
something like that to be able to represent _mm256_movemask_ps(mask) == 255 at
tree level.
