Hi, On Mon, 21 Nov 2016, Richard Biener wrote:
> >> Btw, this probably means that on haswell (or other archs with vf==4) mgrid > >> is slower than necessary. On mgrid you really really want predictive > >> commoning to happen. Vectorization isn't that interesting there. > > Interesting, I will check if there is difference between 2/4 vf. we > > do have cases that smaller vf is better and should be chosen, though > > for different reasons. > > At some time in the past we had predictive commoning done before > vectorization (GCC 4.3 at least). Not relevant here. The testcase and patch associated with it came for 4.5 where predcom was after vectorization already and the latter disabled the former (and mgrid had a 40% performance hit). PR41783 and https://gcc.gnu.org/ml/gcc-patches/2010-01/msg00855.html FWIW. Ciao, Michael.
