> Hi, > I have a finite difference code written in fortran, currently I use g77 > to build this code. I would like to know if it is possible to leverage > gcc vector data types, and SSE instructions etc within the fortran code. > I notice that when using C it is possible to declare variables as vector > type. A while back we tried to let the fortran compiler(I think it was > actually pgf) automagically vectorize but we only got about 10% speed > up. We should get significantly more if all the potential loops were > vectorized. I would like to hand tune some of the code. Is it going to > be possible to vectorize the fortran code using g77/gfortran? Where can > more information be found? -ftree-vectorize enables vectorization in gcc (enabled by default under -O3 since gcc4.3). You may also need to use -fassociative-math if you have reductions on floats. There's some information here: http://gcc.gnu.org/projects/tree-ssa/vectorization.html, but not much tuning hints and such. You can use -ftree-vectorizer-verbose=#, which will report which loops got vectorized and which not and why. dorit > thanks in advance > Burlen > >
