Frederic Riss <frederic.r...@gmail.com> wrote on 31/05/2011 12:34:35 PM:
> Hi Ira, > > thanks for your answer, however: > > On 31 May 2011 08:06, Ira Rosen <i...@il.ibm.com> wrote: > >> This test fails for me because I get 4 vectorized loops instead of 3. > >> There are multiple other tests that generate more vectorization then > >> expected. I'd like to understand the reason for these failures, but I > >> can't see what motivates the choice of only 3 vectorized loops among > >> the 4 vectorizable loops of the test. Can someone enlighten me? > > > > The fourth loop (line 104) has only 3 scalar iterations, too few to > > vectorize unless your target has vectors of 2 shorts. > > My port has vectors of 2 shorts, but I don't expose them directly to > GCC. The V2HI type is defined, but UNITS_PER_SIMD_WORD always returns > 8, which I believe should prompt GCC to use V4HI which is also > defined. > > Regarding slp-3.c I don't get why the loop you point isn't > vectorizable. I my version of the file (4.5 branch), I see 9 short > copies in a loop iterating 4 times (a total of 36 short assignements). > After the vectorization pass, I get 9 V4HI assignments which seem > totally right. I don't see why this shouldn't be the case... You are right. slp-3.c was fixed lately (revision 171569) on trunk for targets with V4HI. I think there are other tests as well that fail because of the vector size assumption. I'm planing to fix them. Ira > > Many thanks, > Fred
