[Bug rtl-optimization/56766] Fails to combine (vec_select (vec_concat ...)) to (vec_merge ...)
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Tue Apr 2 08:08:00 GMT 2013
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56766
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-02 08:08:34 UTC ---
Btw, vec_merge is a special-case of a non-existing vec_shuffle2.
vec_merge (and a vec_suffle2) as opposed to a vec_select (vec_concat (...))
combination has the advantage that we don't need intermediate vector
modes of double size.
So in the long run it might be most profitable to remove vec_merge
and instead introduce vec_shuffle to catch almost all vec_select (vec_concat
())
cases.
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