Jakub Jelinek <ja...@redhat.com> wrote: >On Thu, Oct 31, 2013 at 07:02:28PM +0400, Yuri Rumyantsev wrote: >> Here is a simple fix which allows to vectorize loop marked with >> 'pragma omp simd' even if cost model tells us that vectorization is >> not profitable. >> I checked that on simple test-case is works as expected. >> >> Is it Ok for trunk? >> >> ChangeLog: >> >> 2013-10-31 Yuri Rumyantsev <ysrum...@gmail.com> >> >> * tree-vect-loop.c (vect_estimate_min_profitable_iters): Override >> cost estimation for loops marked as vectorizable. > >That looks too simplistics, IMHO it is undesirable to disregard the >profitability checks together. For #pragma omp simd or #pragma simd >loops, I can understand that we should admit our cost model is not very >high >quality and so in border cases consider vectorizing rather than not >vectorizing, say for force_vect by increasing the scalar cost by some >factor or decreasing vector cost by some factor, but disregarding it >altogether doesn't look wise. The question is what factor should we >use? >150% of scalar cost, something else?
Please improve the cost-model instead. Thanks, Richard. > Jakub
